BY SPACEFLIGHT NOW

Follow the mission of space shuttle Endeavour to exchange resident crews living aboard the International Space Station. Reload this page for the very latest.

SATURDAY, JUNE 29, 2002

Riding atop the Shuttle Carrier Aircraft, Endeavour was returned to Kennedy Space Center today after a two-day cross-country ferry flight from its landing site at Edwards Air Force Base, California. The modified Boeing 747 jet touched down at the Shuttle Landing Facility at 11 a.m. EDT.

Unlikely previous ferry flights, NASA kept the route and planned refueling stops a secret due to security concerns.

Endeavour will be demated from the 747 and towed to its processing hangar to begin preparations for its next mission -- a space station assembly mission at the end of the year.

FRIDAY, JUNE 28, 2002

Nine days after landing at Edwards Air Force Base in California, space shuttle Endeavour began its cross-country piggyback ride atop a Boeing 747 carrier jet today. Bad weather last Wednesday forced the shuttle's landing to be diverted from Kennedy Space Center to Edwards.

Due to security reasons, NASA won't disclose the ferry-flight's route, timeline or planned stopping points.

WEDNESDAY, JUNE 19, 2002

Diverted to California after back-to-back landing delays Monday and Tuesday, the shuttle Endeavour's crew glided to a picture-perfect Mojave Desert touchdown today, bringing a trio of weary space station fliers home after a U.S. record 196 days in space. Read full story.

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1915 GMT (3:15 p.m. EDT)

Endeavour will be towed off the runway in a couple hours to begin preparations for it's cross-country ferry flight back to Kennedy Space Center sometime next week. The shuttle's next flight is slated for launch no sooner than October 6. Endeavour will deliver the port truss segment P1 to that will become part of the station's backbone.

The shuttle and Expedition 4 astronauts will return to a welcoming ceremony at Ellington Field's Hangar 990 in Houston near the Johnson Space Center around 3 p.m. local time Friday. The public is invited to attend.

1905 GMT (3:05 p.m. EDT)

All seven astronauts aree now off the shuttle and inside the motorized Crew Transport Vehicle. It is expected that at least some of the four orbiter astronauts will make the traditional walkaround of the Endeavour on the runway shortly. But the three Expedition 4 crewmembers will remain in the people mover.

Later, the astronauts will be driven to the crew quarters for dinner and hot showers.

1855 GMT (2:55 p.m. EDT)

Following Endeavour's landing, the astronauts went through standard post-landing safing of the shuttle and its systems. The body flap was set, the external tank umbilical doors on the shuttle's belly were opened, the side hatch and drag chute pyrotechnics were safed, and the landing gear is verified safed. The main engine nozzles were then gimbaled to the "rain drain" position and the three Auxiliary Power Units were shut down. On the runway, workers arrived with instruments to "sniff" the shuttle's exterior to check for any hazardous vapors before the rest of the convoy arrived and the orbiter's hatch was opened.

1846 GMT (2:46 p.m. EDT)

The three Expedition 4 crewmembers have left the shuttle along with Philippe Perrin.

1841 GMT (2:41 p.m. EDT)

The astronauts are now beginning to make their way off Endeavour.

1830 GMT (2:30 p.m. EDT)

The Crew Transport Vehicle -- a modified airport "People Mover" -- has pulled up to the Endeavour's crew hatch for the astronauts to enter. The CTV features beds and comfortable seats for the astronauts to receive medical checks after returning to Earth's gravity from the weightless environment of space.

1805 GMT (2:05 p.m. EDT)

Post-landing safing of Endeavour is underway by the astronauts following a smooth touchdown today.

Here are the preliminary landing times in Eastern Daylight Time and Mission Elapsed Time:

Main Gear Touchdown
1:57:41 p.m. EDT
MET: 13 days, 20 hours, 34 minutes, 52 seconds

Nose Gear Touchdown
1:57:53 p.m. EDT
MET: 13 days, 20 hours, 35 minutes, 04 seconds

Wheels Stop
1:58:45 p.m. EDT
MET: 13 days, 20 hours, 35 minutes, 56 seconds

1758 GMT (1:58 p.m. EDT)

WHEELS STOP. Endeavour has completed a successful mission that shuttled the Expedition 5 crew to the station to continue the permanent human presence in space and brought Expedition 4 home after 196 days in orbit.

1758 GMT (1:58 p.m. EDT)

TOUCHDOWN! Main gear touchdown. Drag chute deployed. Nose gear touchdown. Space shuttle Endeavour is back on Earth after traveling 5.8 million miles during it's two-week mission to exchange the new resident crews of the International Space Station.

1757 GMT (1:57 p.m. EDT)

Landing gear down and locked. Standing by for touchdown.

1756 GMT (1:56 p.m. EDT)

Field in sight. Commander Cockrell can see the runway as he pilots Endeavour to landing on Runway 22 at Edwards Air Force Base. The shuttle descending at a rate seven times steeper than that of a commercial airliner.

1755 GMT (1:55 p.m. EDT)

Endeavour is in the Heading Alignment Cylinder, an imaginary circle to align with Runway 22. Cockrell is piloting the shuttle through a 228-degree right-overhead turn. And the twin sonic booms have been heard in Edwards area, announcing the shuttle's arrival.

1754 GMT (1:54 p.m. EDT)

Commander Ken Cockrell has taken manual control of Endeavour.

1753 GMT (1:53 p.m. EDT)

Now five minutes from landing at Edwards Air Force Base, California. About 60 miles to go. Mission Control has given the crew a "go" for normal drag chute deployment after main gear touchdown.

1751 GMT (1:51 p.m. EDT)

Endeavour is in the final bank to scrub off speed.

1750 GMT (1:50 p.m. EDT)

Air data probes have been deployed from the shuttle's nose to feed air speed, altitude and angle of attack information to the computers for navigation.

1748 GMT (1:48 p.m. EDT)

Touchdown is now 10 minutes away. The shuttle, just a glider during its return to Earth, is right on the planned ground track. Altitude 27 miles, 287 miles from the runway.

1747 GMT (1:47 p.m. EDT)

The TACAN navigation units aboard Endeavour are now receiving data from beacons located at the ground at Dryden Flight Research Center at Edwards.

1745 GMT (1:45 p.m. EDT)

Altitude 33 miles, 577 miles to the runway.

1744 GMT (1:44 p.m. EDT)

The shuttle is reversing its bank to further reduce speed.

1743 GMT (1:43 p.m. EDT)

Endeavour is now 1,000 miles to the runway, speeding along at Mach 17.

1739 GMT (1:39 p.m. EDT)

Now 19 minutes from landing. Endeavour is 1,700 miles to the runway with an altitude of 42 miles.

1736 GMT (1:36 p.m. EDT)

Endeavour is 2,400 miles to touchdown, altitude 44 miles, sink rate is now 70 feet per second.

1732 GMT (1:32 p.m. EDT)

Endeavour has begun the first of four banks to scrub off speed as it plunges into the atmosphere. These turns basically remove the energy Endeavour built up during launch.

1726 GMT (1:26 p.m. EDT)

ENTRY INTERFACE. The protective tiles on the belly of Endeavour are now feeling heat beginning to build as the orbiter enters the top fringes of the atmosphere -- a period known as Entry Interface.

The shuttle is flying with its nose elevated 40 degrees, wings level, at an altitude of 400,000 feet, passing over the southern Pacific Ocean, about 4,400 nautical miles from the landing site, at a velocity of Mach 25, descending at a rate of over 500 feet per second.

1721 GMT (1:21 p.m. EDT)

Endeavour's onboard computers have switched to the OPS-304 program, which governs entry phase of the mission.

1716 GMT (1:16 p.m. EDT)

All three auxiliary power units are running to supply pressure to the shuttle's hydraulic systems, which in turn move Endeavour's aerosurfaces and deploy the landing gear. One unit was started prior to the deorbit burn; the others just a few moments ago. The units are only activated during the launch and landing phases of the shuttle mission.

1714 GMT (1:14 p.m. EDT)

The shuttle's track home will take the craft above the Pacific Ocean on northeastward track towards Edwards Air Force Base. The shuttle will make landfall above Southern California about six minutes before touchdown, bound for the Mojave Desert military site. Once in the vicinity of Edwards, commander Cockrell will perform a wide, sweeping 228-degree right-overhead turn to align with Runway 22 -- the northeast to southwest strip.

1700 GMT (1:00 p.m. EDT)

Onboard guidance is maneuvering Endeavour from its heads-down, tail-forward position needed for the deorbit burn to the reentry configuration of heads-up and nose-forward. The nose also will be pitched upward 40 degrees. In this new position, the black tiles on the shuttle's belly will shield the spacecraft during the fiery plunge through the Earth's atmosphere with temperatures reaching 3,000 degrees F. Endeavour will begin interacting with the upper fringes of the atmosphere above the South Pacific in about a half-hour.

1653 GMT (12:53 p.m. EDT)

DEORBIT BURN COMPLETE. Endeavour has successfully completed the deorbit burn, committing the shuttle for its journey back to Earth. Landing is scheduled for 1:58 p.m. EDT at Edwards Air Force Base, California.

1650 GMT (12:50 p.m. EDT)

DEORBIT BURN IGNITION. Flying upside down and backwards above the northwestern Indian Ocean, off the east coast of Africa, Endeavour has begun the deorbit burn. The firing of the two orbital maneuvering system engines on the tail of the shuttle will last two minutes and 55 seconds, slowing the craft to slip from orbit. The retro-burn will put Endeavour on a course for touchdown at 1:58 p.m. EDT on the concrete Runway 22 at Edwards Air Force Base in California.

1646 GMT (12:46 p.m. EDT)

Endeavour has maneuvered to the deorbit burn attitude. The shuttle is flying upside-down and backwards with its tail pointed in the direction of travel. The shuttle's vent doors have been closed and final configuring of the onboard computers has been completed.

Also, pilot Paul Lockhart has activated one of three auxiliary power units in advance of the deorbit burn. The other two APUs will be started later in the descent to provide pressure needed to power shuttle's hydraulic systems that move the wing flaps, rudder/speed brake, drop the landing gear and steer the nose wheel. NASA ensures that at least one APU is working before committing to the deorbit burn since the shuttle only needs a single unit to make a safe landing.

1625 GMT (12:25 p.m. EDT)

GO FOR THE DEORBIT BURN! With very favorable landing weather today at Edwards Air Force Base in California, entry flight director John Shannon in Mission Control has given space shuttle Endeavour's astronauts the "go" to perform the deorbit burn at 12:50 p.m. EDT for return to Earth.

The upcoming two-minute, 55-second retrograde burn using the twin orbital maneuvering system engines on the tail of Endeavour will slow the shuttle's velocity by just over 300 feet per second to slip the craft out of orbit and begin the plunge back into the atmosphere.

Endeavour is headed to a landing at 1:58 p.m. EDT on Runway 22 at Edwards. The landing will conclude the 14-day STS-111 mission.

1624 GMT (12:24 p.m. EDT)

Entry flight director John Shannon is polling his team in Mission Control and receiving a final update on weather before making the decision on the deorbit burn.

1617 GMT (12:17 p.m. EDT)

Proving that Mission Control made the right decision to give up on Kennedy Space Center today, it is beginning to pour the rain here. Thunder and lightning are also being experienced here at the Cape. Endeavour's landing time was 12:27 p.m. EDT.

1550 GMT (11:50 a.m. EDT)

Now one hour away from the deorbit burn. Here's a look at the timeline to come:

12:30 PM......Mission control 'go' for the burn
12:36 PM......Mission specialists seat ingress
12:45 PM......Single hydraulic system APU start
12:50:27 PM...Deorbit ignition
12:53:22 PM...Deorbit burn complete
01:02:25 PM...TDRS-West acquisition of signal
01:26:34 PM...The shuttle hits the discernible 
                atmosphere (76 miles up)
01:31:27 PM...17-degree left roll command
01:45:07 PM...56-degree roll reversal
01:51:50 PM...Velocity less than mach 2.5
01:54:07 PM...Velocity less than mach 1
01:54:55 PM...Shuttle banks to line up on
                runway 22
01:58:10 PM...Landing

1515 GMT (11:15 a.m. EDT)

It is an absolutely beautiful day in the Mojave Desert at Edwards Air Force Base, California. The skies are clear, visibility is unrestricted and winds are from the west-southwest at 250 degrees at 12 peak 18 knots.

1505 GMT (11:05 a.m. EDT)

Shuttle Endeavour is now aiming for a landing in California after bad weather ruled out a Florida homecoming for the third straight day. Endeavour's twin orbital maneuvering engines will be fired for two minutes and 55 seconds starting at 12:50 p.m. EDT, slowing the shuttle by 303 feet per second to drop from orbit. Touchdown on the concrete Runway 22 at Edwards Air Force Base is expected at 1:58 p.m. EDT (1758 GMT).

Endeavour's detour to the backup landing site snaps a five-mission streak of homecomings at Kennedy Space Center. It will be the 49th Edwards landing in the history of the space shuttle program. The most recent was STS-100 on May 1, 2001. KSC is the most used landing site for the shuttle with 59 landings to date. White Sands in New Mexico supported one back in 1982.

1454 GMT (10:54 a.m. EDT)

WAVE OFF! With the clouds beginning to thicken, Mission Control has decided to give up on Kennedy Space Center and not take this down to the wire as had been planned. So it appears Endeavour is now California bound with landing at Edwards Air Force Base targeted for 1:58 p.m. EDT. The weather in the Mojave Desert is favorable today.

1449 GMT (10:49 a.m. EDT)

Now 30 minutes to the deorbit burn. Weather remains dynamic and too close to call due to low clouds and the chance of more shower development. A "go/no go" decision for the burn is expected in about 20 minutes.

1440 GMT (10:40 a.m. EDT)

Pilot Paul Lockhart has completed the auxiliary power unit prestart, which positions switches in the cockpit in the ready-to-start configuration.

1436 GMT (10:36 a.m. EDT)

The crew is now starting a steering check on Endeavour's orbital maneuvering system engines as a precursor to the upcoming deorbit burn, should the weather permit.

1415 GMT (10:15 a.m. EDT)

The two issues that meteorologists are tracking are low clouds over the runway and convection that could cause more showers to develop within 30 miles of the landing site. So the crew has been told that a final "go/no go" decision won't be made until just minutes before the deorbit burn.

The challenge to forecasting landing weather is the fact that the meteorologists have be sure of how the conditions will change from the time of the deorbit burn and touchdown. For the upcoming KSC landing opportunity, the burn brgins at 11:19 a.m. and landing won't occur for more than an hour -- at 12:27 p.m.

1350 GMT (9:50 a.m. EDT)

Entry flight director John Shannon intends to take the decision down to the wire to determine if weather will be acceptable for Endeavour to land at Kennedy Space Center today. The crew was told they will be given a "go" to begin their fluid loading protocol on schedule, whereby they drink large amounts of fluids to assist in the readaptation to Earth's gravity.

So flight controllers are giving their all in hopes of getting Endeavour back to Florida on this final landing opportunity into KSC today.

The clouds and rain that have been streaming from the Gulf of Mexico into Florida seem to be breaking up as they reach the central and eastern part of the state, which is good news for the Cape.

The decision to proceed with the deorbit burn to brake from space must be given a few minutes before the 11:19 a.m. EDT ignition time.

1325 GMT (9:25 a.m. EDT)

Mission Control has given the crew a "go" to suit up in possibility for landing at Kennedy Space Center today. The storms that forecasters have been watching all morning have dissipated after moving into the central part of Florida. So with some hope, the astronauts were told to resume their deorbit prep timeline.

If Endeavour is cleared to land at KSC, the two-minute, 55-second firing of the shuttle's twin orbital maneuvering system engines would begin at 11:19 a.m. EDT to slow the ship by 304 feet per second to drop from space. Landing on Runway 15 would occur at 12:27 p.m. EDT.

Should the weather not cooperate for this final KSC landing opportunity of the day, Endeavour likely will be sent to Edwards Air Force Base in California. The deorbit burn for the first Edwards opportunity of the day would begin at 12:50 p.m., followed by touchdown on Runway 22 at 1:58 p.m. EDT.

1215 GMT (8:15 a.m. EDT)

WAVE OFF! The first Kennedy Space Center landing opportunity has been waved off, meaning Endeavour will spend at least one more 90-minute orbit in space today. The next available landing chance would start with a deorbit burn at 11:19 a.m. and touchdown at KSC at 12:27 p.m. EDT.

Entry flight director John Shannon just received another weather briefing in advance of his decision whether to have the crew begin donning their launch and entry spacesuits. The forecasters are saying the area of rain and storms over Tampa continues to move in the direction of the Cape, making the first landing chance "no go" today. And with that, Shannon decided to give up on this first landing opportunity and allow the crew to remain comfortable for another 90 minutes or so.

The hope is the weather system will pass through the KSC area in time for the second landing opportunity four hours from now.

In any event, Edwards is still looking favorable to support landing today if Endeavour has to be diverted.

1150 GMT (7:50 a.m. EDT)

Deputy chief NASA astronaut Kent Rominger is now switching from the T-38 to the Shuttle Training Aircraft for continued weather reconnaissance flights around Kennedy Space Center and Central Florida this morning. Meteorologists are monitoring a massive area of rain and thundershowers over the west coast of Florida near Tampa.

The deorbit burn for Endeavour to brake from space for the first landing opportunity of the day in Florida would occur at 9:44 a.m. EDT for touchdown at KSC at 10:53 a.m. EDT.

1107 GMT (7:07 a.m. EDT)

For the third straight morning, Endeavour's 60-foot long payload bay doors have been swung closed and latched in preparation for reentry and landing.

Commander Cockrell will now transition Endeavour's onboard computers from the OPS-2 software used during the shuttle's stay in space to OPS-3, which is the software package that governs entry and landing.

The plan is to continue with the deorbit prep timeline until the point where the astronauts begin donning their suits. If weather in Florida does not look like it will support landing, then the crew can hold off suiting up until later this morning in advance of their homecoming to California, if that is decided. For a timeline of today's activities, see our Entry and Landing page.

1100 GMT (7:00 a.m. EDT)

Mission Control has given the crew a "go" to again close Endeavour's payload bay doors for entry.

At KSC, deputy chief NASA astronaut Kent Rominger is in charge of weather reconnaissance today, flying first in a T-38 jet and later this morning in the Shuttle Training Aircraft.

The two specific concerns at the shuttle runway are showers within 30 miles of the strip and a chance of low clouds at 3,000 feet, both of which would be violations of the landing weather rules.

1050 GMT (6:50 a.m. EDT)

Meteorologists were hopeful Florida's weather would finally improve today, giving a chance for Endeavour to land at Kennedy Space Center this morning. But moisture continues to stream across Florida from the Gulf of Mexico, spreading clouds and rain. So NASA is not optimistic that the shuttle will be able to come home to KSC today.

If Florida remains "no go" for Endeavour, mission managers will divert the shuttle to backup landing site at Edwards Air Force Base in California today where the weather is just fine.

Here are all the landing times for today at both Kennedy and Edwards (all in Eastern; RW=runway):

ORBIT...DEORBIT BURN...LANDING........SITE..RW
   
215.....09:43:49 a.m...10:52:32 a.m...KSC...15
216.....11:19:17 a.m...12:27:00 p.m...KSC...15
217.....12:50:27 p.m...01:58:10 p.m...EDW...22
218.....02:26:45 p.m...03:33:21 p.m...EDW...22
219.....04:05:31 p.m...05:10:41 p.m...EDW...22

TUESDAY, JUNE 18, 2002

As expected, storm buildups near the Kennedy Space Center forced entry flight director John Shannon to call off today's attempt to bring the shuttle Endeavour back to Earth. Instead, the shuttle crew will remain in orbit for a second additional day, extending the U.S. endurance record set by the returning Expedition 4 space station crew from 195 days to 196. Read full story.

1439 GMT (10:39 a.m. EDT)

Yet another day in space! For the second straight day, bad weather in Florida has prevented space shuttle Endeavour from returning to Earth. So the astronauts get another bonus day aloft, extending the Endeavour's mission to 14 days in duration and the Expedition 4 station crew's U.S. endurance record to 196 days.

NASA passed up the opportunity to try the backup landing site at Edwards Air Force Base in California today. A Florida landing is preferred since it costs a $1 million and a week's worth of processing time by having to ferry the shuttle across the country. In addition, a California landing would all but ensure Endeavour's next mission to the space station -- now planned of Oct. 6 -- would be delayed about a month until after the Soyuz capsule rotation that must occur in late October.

The winds were gusty at Edwards today anyway.

There are five landing chances on Wednesday:

215....KSC.....09:47 a.m....10:52 a.m.
216....KSC.....11:23 a.m....12:28 a.m.
217....EDW.....12:54 a.m....01:58 p.m.
218....EDW.....02:31 p.m....03:34 p.m.
219....EDW.....04:08 p.m....05:10 p.m.

Even though Endeavour has enough fuel and consumables to safely remain in space through Thursday, mission managers don't want to stretch it that far. Thus, Endeavour will most likely land on one coast or the other tomorrow if the weather permits.

The forecast for Kennedy Space Center tomorrow is much improved with dry air building into the Sunshine State. There is just a chance of rainshowers around the Cape. At Edwards, favorable conditions are expected with decreased winds.

1359 GMT (9:59 a.m. EDT)

At least one more orbit. NASA has officially waved off the first landing opportunity into Kennedy Space Center. Forecasters want to continue watching storms to the west and southwest before throwing in the towel for the day.

With the previous decision not to go Edwards this afternoon, the final chance to land Endeavour today would begin with a deorbit burn at 12:24 p.m. and landing at 1:31 p.m. EDT.

1344 GMT (9:44 a.m. EDT)

Just like yesterday, Mission Control has told Endeavour's astronauts to hold off on the "fluid loading" protocol, which sees the crew drink load amounts of fluids to assist the re-adaptation to Earth's gravity. The decision to delay this activity is often a precursor to landing being delayed.

330 GMT (9:30 a.m. EDT)

Although weather continues to look acceptable at the moment at Kennedy Space Center, meteorologists are still saying conditions will worsen by the time of the first landing opportunity. There are storms to the west and the heating of the day will cause more storms to develop.

1316 GMT (9:16 a.m. EDT)

The decision has just been made not to send Endeavour to Edwards Air Force Base in California today. So the focus remains on the prime landing site at Kennedy Space Center this morning. If weather does not permit a landing in Florida today, the shuttle will remain in space and try again Wednesday. The forecast for tomorrow is better for KSC and favorable at Edwards.

1300 GMT (9:00 a.m. EDT)

Commander Ken Cockrell has received an update on data from this first landing opportunity to Kennedy Space Center. The two-minute, 56-second deorbit burn to brake from space would begin at 10:47:11 a.m. EDT, slowing the shuttle by 305 feet per second. Endeavour would begin an hour-long, powerless glide back to Earth for touchdown at 11:55 a.m. EDT on Runway 15.

1300 GMT (9:00 a.m. EDT)

Mission Control continues to monitor the weather in Florida. The "go/no go" decision for the deorbit burn is scheduled about 90 minutes from now.

1215 GMT (8:15 a.m. EDT)

Deputy chief NASA astronaut Kent Rominger is flying a T-38 training jet around Kennedy Space Center for weather reconnaissance. He is reporting conditions are generally acceptable at the moment with some thin clouds at 9,000 and 20,000 feet and no rain. But a strong line of rain and storms is stretched across Florida and expected to move into the KSC area later this morning. The first orbit that brings Endeavour in range for landing at the Florida spaceport today isn't until 11:55 a.m. EDT.

Although the backup landing site at California's Edwards Air Force Base is available today, no decisions have been made to divert the shuttle there today if KSC remains "no go". NASA might keep Endeavour in space another day and try Florida again tomorrow when the weather is expected to be much better.

1211 GMT (8:11 a.m. EDT)

The payload bay doors are now closed and locked for entry.

1200 GMT (8:00 a.m. EDT)

Mission Control has given the crew a "go" to close Endeavour's payload bay doors to preserve the option of landing on today's first opportunity. However, the weather forecast for Kennedy Space Center remains dismal.

1130 GMT (7:30 a.m. EDT)

For a timeline of today's activities, see our Entry and Landing page.

1050 GMT (6:50 a.m. EDT)

It is Day No. 2 of attempts to get Endeavour back to Earth to complete its mission and shuttle the Expedition 4 crew home after more than six months in space. But just like yesterday, the weather is less than favorable at the Kennedy Space Center landing strip.

Meteorologists are calling for low clouds, rain and even thunderstorms for the two landing opportunities at KSC today. The forecast for Wednesday is improved with just a chance of showers within 30 miles of the runway.

Closure of the shuttle's payload bay doors is about 90 minutes away in support of the first landing opportunity, which would see Endeavour deorbit at 10:47 a.m. and touch down at 11:55 a.m. EDT.

If the weather prevents Endeavour from returning to Florida today, NASA will have to decide whether to divert the shuttle to Edwards Air Force Base in California this afternoon or extend the mission another day and try again tomorrow.

The space agency prefers landing at KSC since it saves the $1 million and about a week in processing time by not having to ferry the shuttle across the country from the West Coast. In addition, a California landing would all but ensure Endeavour's next mission to the station -- now planned of Oct. 6 -- would be delayed about a month until after the Soyuz capsule rotation that must occur in late October.

At Edwards, the forecast is marginal today with crosswinds gusting up to the limits. The winds are expected to ease tomorrow.

Endeavour has enough supplies to remain in space through Thursday.

MONDAY, JUNE 17, 2002
1745 GMT (1:45 p.m. EDT)

Mission Control has updated the landing times for Tuesday. All times are EDT:

Orbit..Site....Deorbit......Touchdown
200....KSC.....10:47 a.m....11:55 a.m.
201....KSC.....12:24 p.m....01:31 p.m.
202....EDW.....01:54 p.m....03:00 p.m.
203....EDW.....03:32 p.m....04:36 p.m.

1730 GMT (1:30 p.m. EDT)

Here's a look at the landing weather forecasts for Kennedy Space Center and Edwards Air Force Base over the next couple of days. Both sites have problems for Tuesday.

For Kennedy Space Center on Tuesday, meteorologists are calling for scattered clouds at 3,000 feet, broken at 8,000 and overcast at 20,000, visibility of 7 miles, southerly winds from 190 degrees at 8 peaking to 14 knots. The concerns are showers and thunderstorms within 30 miles and the chance the deck of clouds at 3,000 will become broken, constituting a ceiling.

At Edwards on Tuesday, clear skies are predicted with 7 miles visibility and southwesterly winds from 250 degrees at 17 peaking to 26 knots. The second orbit into Edwards is expected to have winds from 260 degrees at 20 peaking to 30 knots. Those conditions would violate crosswind limits.

Wednesday is better at KSC with only a chance of showers within 30 miles the concern. The winds are forecast acceptable at Edwards on Wednesday, too.

1620 GMT (12:20 p.m. EDT)

The Mission Management Team has just decided to activate Edwards Air Force Base for landing support tomorrow. The plan will be to focus on Kennedy tomorrow, but if weather remains unacceptable then NASA will look at Wednesday's forecast for both sites to determine if Endeavour should be brought down in California tomorrow.

The landing times for Tuesday and Wednesday:

TUESDAY
200....KSC.....10:51 a.m....11:56 a.m.
201....KSC.....12:28 p.m....01:32 p.m.
202....EDW.....01:58 p.m....03:02 p.m.
203....EDW.....03:35 p.m....04:38 p.m.

WEDNESDAY
215....KSC.....09:47 a.m....10:52 a.m.
216....KSC.....11:23 a.m....12:28 a.m.
217....EDW.....12:54 a.m....01:58 p.m.
218....EDW.....02:31 p.m....03:34 p.m.
219....EDW.....04:08 p.m....05:10 p.m.

1600 GMT (12:00 p.m. EDT)

NASA officials are debating whether to call up the alternate landing site at Edwards Air Force Base in California for support tomorrow. For the moment, the two landing opportunities available on Tuesday are at Kennedy Space Center with touchdown at 11:56 a.m. or 1:32 p.m. EDT.

1537 GMT (11:37 a.m. EDT)

Another day in space! NASA has decided the weather will simply not cooperate at Kennedy Space Center today, forcing Endeavour to remain aloft for another 24 hours. For the returning Expedition 4 space station crew, this extends their U.S. endurance record to at least 195 days.

The weather for tomorrow does not look much better. Wednesday does show signs of improvement. Endeavour has enough consumables and supplies to remain in space through Thursday if needed.

1524 GMT (11:24 a.m. EDT)

The seven astronauts remain suited up as Endeavour takes one more spin around the globe while mission managers monitor the dynamic weather conditions at Kennedy Space Center.

Although there isn't a lot of optimism that weather will improve for the second landing opportunity, which would see a deorbit burn at 1:30 and touchdown at 2:36 p.m. EDT, NASA decided to preserve its options today and continue tracking the rain and clouds. If the weather remains out of limits, Endeavour will stay in space until Tuesday.

"Taco, we're going to wave off this first rev and still stay in a config to try it the second time around," astronaut Bill Oefelein radioed commander Ken Cockrell. "We're still looking at the weather, particularly the stuff to the northwest and west that's starting to build, as well as the winds are kind of touching on the crosswind limit and that low broken deck is going scattered and back to broken. So we're still looking at that, but we're going to officially wave off this first attempt."

1510 GMT (11:10 a.m. EDT)

WAVE OFF! Endeavour will remain in space for at least another orbit. Mission Control says it wants to continue to watch the weather in hopes of improvement. If conditions do suddenly improve, Endeavour would brake from orbit at 1:30 p.m. for landing at Kennedy Space Center at 2:36 p.m. EDT.

Weather is currently unacceptable due to rain within 30 miles of the landing strip and low clouds. The winds are also gusty.

1500 GMT (11:00 a.m. EDT)

Entry flight director John Shannon says the team will continue to track the weather for another half-hour or so before he makes a decision on today's landing opportunities. It is possible he could decide to scrub for the day, allowing the crew to get out of their suits and re-schedule for tomorrow. The other option is to wave off the first orbit and watch the conditions for today's 2:36 p.m. EDT landing opportunity in Florida.

1451 GMT (10:51 a.m. EDT)

Mission Control has just radioed Endeavour's astronauts and told them to hold off on the "fluid loading" protocol, which sees the crew drink load amounts of fluids to assist the re-adaptation to Earth's gravity. The decision to delay this activity is often a precursor to landing being waved off.

At present, conditions at Kennedy Space Center are "no go" for landing due to a broken deck of clouds at 2,000 feet and showers in the area. Crosswinds are now within limits, however.

1445 GMT (10:45 a.m. EDT)

Now about 45 minutes from entry flight director John Shannon making his final "go/no go" decision whether to allow Endeavour to come home on the first of two landing opportunities today at Kennedy Space Center. The backup landing site at Edwards Air Force Base in California is not being staffed to support today.

The challenge today, as it always is for shuttle landings, is having acceptable weather at the landing site when the flight director makes the call and ensuring conditions will remain favorable over the next 90 minutes. The shuttle will deorbit at 11:51 a.m. EDT today and touch down at 12:59 p.m. EDT.

One other concern that NASA must consider is the possibility of hail from thunderstorms this afternoon that could damage Endeavour on the runway before it can be towed to the orbiter processing hangar.

1422 GMT (10:22 a.m. EDT)

Endeavour commander Ken Cockrell and pilot Paul Lockhart will now begin suiting up and strapping into their seats for today's possible landing. The rest of the crew will don their suits shortly.

Clocks are ticking down to the planned two-minute, 55-second deorbit burn beginning at 11:51:20 a.m. EDT, which would slow the ship by about 300 feet per second to brake from orbit. Landing is scheduled for 12:59 p.m. EDT on Runway 15.

Weather remains the main threat to Endeavour's homecoming at Kennedy Space Center, with crosswinds currently one-knot above the limit at the runway and clouds and rain all around Florida.

1346 GMT (9:46 a.m. EDT)

The crew is now transitioning Endeavour's onboard computers from the OPS-2 software used during the shuttle's stay in space to OPS-3, which is the software package that governs entry and landing.

1321 GMT (9:21 a.m. EDT)

Endeavour's clam-shell-like payload bay doors have been closed and locked in preparation for today's fiery descent into Earth's atmosphere and landing at Kennedy Space Center.

NASA continues to carefully monitor weather conditions across Florida. There are two weather systems -- one to the north of the Cape and another to the south. Meteorologists say in addition to the systems, thunderstorms will likely fire up in the central part of the state as day wears on.

Entry flight director John Shannon has until about 11:30 a.m. EDT to make a final "go/no go" decision to permit Endeavour to fire its manuevering engines to brake from orbit. The firing at 11:51 a.m. would slip the shuttle from space for the hour-long, powerless glide back to Earth for a pin-point landing at 12:59 p.m. EDT.

If weather is unacceptable for the first landing opportunity, Endeavour will remain in space for another orbit while meteorologists watch conditions. The final landing chance today would start with a deorbit engine firing at 1:30 p.m. and landing at KSC at 2:36 p.m.

Should weather preclude both opportunities today, the shuttle would stay aloft for 24 more hours and try again Tuesday.

1150 GMT (7:50 a.m. EDT)

Despite a dismal weather forecast today, Mission Control and Endeavour's astronauts are pressing ahead with preparations for a possible landing at Kennedy Space Center, Florida. Two landing opportunities exist at 12:59 p.m. and 2:36 p.m. EDT.

Entry flight director John Shannon has received his first weather briefing of the morning and the news is not positive. Meteorologists are calling for broken clouds at 3,000 and 8,000 feet and overcast conditions at 20,000 feet, visibility of 7 miles, southwesterly winds from 230 degrees at 11 peaking to 17 knots and showers/thunderstorms within 30 miles of the runway.

Based on those conditions, the low cloud ceiling, crosswinds and precipitation flight rules all would be violated.

But there is always a bit of hope that the dynamic Florida weather could change, allowing Endeavour to brake from orbit and bring the Expedition 4 crew home after six months in orbit.

For a timeline of today's activities, see our Entry and Landing page.

Watch this page for the latest updates throughout the day!

SUNDAY, JUNE 16, 2002

Forecasters are predicting rain and possible thunderstorms for Endeavour's Florida landing opportunities Monday. NASA managers want to get the shuttle back on the ground in Florida if at all possible to have any chance at all of holding an October launch date for Endeavour's next space station assembly mission. Read full story.

SATURDAY, JUNE 15, 2002

The shuttle Endeavour undocked from the international space station Saturday as the two spacecraft sailed 240 miles above central Asia just west of the Baikonur Cosmodrome in Kazakstan. Read full story.

1615 GMT (12:15 p.m. EDT)

The separation maneuver by Endeavour has been performed and the shuttle is now quickly departing the vicinity of the space station.

1614 GMT (12:14 p.m. EDT)

Endeavour has moved above the station again. This is where the separation burn will be performed.

1603 GMT (12:03 p.m. EDT)

Endeavour is back out in front of the station to complete a full lap around the complex.

1553 GMT (11:53 a.m. EDT)

The shuttle is now directly below the station.

1540 GMT (11:40 a.m. EDT)

Endeavour has reached a point directly behind the station in terms of the direction of travel of the two spacecraft around the Earth, which is known as the -V bar.

1529 GMT (11:29 a.m. EDT)

Endeavour is reaching a point directly above the space station.

1517 GMT (11:17 a.m. EDT)

Under the control of pilot Paul Lockhart, Endeavour has begun the lap-and-a-quarter fly-around of the International Space Station so the shuttle astronauts can take photos to document the outpost. The fly-around starts with the shuttle in front of the station, takes Endeavour to a point directly above the complex, then behind it, looping below and back out in front. After climbing above the station for a second time, the final separation engine firing will be performed. This burn will send Endeavour away from the vicinity of the station.

1511 GMT (11:11 a.m. EDT)

The shuttle is now about 400 feet from the station.

1503 GMT (11:03 a.m. EDT)

Distance is now 240 feet.

1450 GMT (10:50 a.m. EDT)

Separation distance now 160 feet.

1445 GMT (10:45 a.m. EDT)

The shuttle is now 115 feet in front of the station, continuing to move away.

1438 GMT (10:38 a.m. EDT)

Endeavour is now 50 feet from the station, backing away at about 0.2 feet per second. The shuttle is headed to a point about 450 feet away to begin a one-and-a-quarter lap fly around of the station.

1432 GMT (10:32 a.m. EDT)

UNDOCKING! Endeavour is slowing backing away from the International Space Station after an 8-day visit to the outpost that rotated the resident crews, delivered tons of supplies and installed the new mobile base for the Canadarm2 robotic arm.

1430 GMT (10:30 a.m. EDT)

About two minutes until undocking. The command has been issued to begin driving open the hooks holding Endeavour and station together. Once the hooks and latches are opened, one final command will be sent to undock the shuttle.

1429 GMT (10:29 a.m. EDT)

The steering jets on Endeavour are inhibited for the period of physical undocking from the station. The separation occurs when large springs push the two craft apart. Once the shuttle is a couple feet away from the station and the docking devices are clear of one another, pilot Paul Lockhart will fire Endeavour's thrusters to continue the movement away.

1421 GMT (10:21 a.m. EDT)

Exoedition 5 astronaut Peggy Whitson reports the station is now ready for undocking.

1417 GMT (10:17 a.m. EDT)

Now 15 minutes from the scheduled departure of Endeavour from the space station. The undocking is expected to occur about 240 miles above western Kazakhstan in Central Asia.

1414 GMT (10:14 a.m. EDT)

Mission Control has given the astronauts a "go" for undocking on-time at 10:32 a.m. EDT today.

1332 GMT (9:32 a.m. EDT)

Undocking of space shuttle Endeavour from the space station is now one hour away. Hatch closure between the two spacecraft occurred at 8:23 a.m. EDT today, concluding 7 days, 17 hours and 15 minutes of joint time.

The shuttle will be under the control of rookie pilot Paul Lockhart for today's 10:32 a.m. undocking and the subsequent flyaround maneuver. He described the shuttle's departure in this pre-flight interview:

"It's basically a reversal of the process of what we did when we docked. You know, when we docked, we came together and then we had to go through a series of steps in order to attach the two pieces together. And then, we had to go through a series of steps to open up all the hatches. Well, we've got to reverse that. We've got to start closing hatches, equalize pressures, and so forth. And then we have to actually go through the process that will separate the...shuttle from the station.

"We have a series of springs; once you come in, end docking and some of the mechanisms start to release springs and capture fixtures and so forth like this. Once they become released, there's a series of springs that actually push the Orbiter away from the station.

"Then, I will, with the guidance of Taco, Ken Cockrell, watching me start to fly the vehicle, start to fly the Orbiter away from the station. And, I liken a little bit of this and the rendezvous a little bit to air-to-air refueling in aircraft which some people may realize we have two vehicles that are moving at a high rate of speed, but their relative velocity is really low. So, the two vehicles themselves are moving at a high rate of speed, but they're moving real slow to each other. But, it's never stable. In other words, it's not like this one vehicle is parked and this vehicle is parked. It's always a constant maneuvering between the two.

"And so, when you dock and when you undock, it's the same thing. You get a separation; but immediately, you have orbital mechanics effects start to take effect. And, if I wasn't to do any other inputs, once we started to separate then my, the Orbiter itself, as I started backing away, would start to climb. So, I have to keep making inputs in order to maintain the axis that I want to separate on.

"I'll fly out to about 450 feet, which takes about 45 minutes or so, because we move away at a very slow rate of about 0.15 feet per second. And, that's just to maintain safety. But, it's also because we're concerned about impingement of my, of the shuttle reaction control system, the thrusters; we don't want to plume or have any of the gases from that hit part of the critical parts of the station. So, we'll move out to 450 feet at a slow rate; and then at 450 feet I'll begin to fly the Orbiter around the station.

"And, maintaining this 400 feet, between 400 and 500 feet, and I'll actually fly a 360 circle, or as much as fuel as there is allowed. And, the whole idea there is to, as we separate, start taking pictures of the Orbiter, or of the Orbiter itself and of the station. And then, specifically of the station as we separate. And then, as I fly around, we'll be taking lots of pictures. And, it's not just because we're taking pictures because it's something neat to look at, (which it is!) but because we have to document the condition that the station is in. They'll use it, our pictures, and look at those with previous pictures and the ones subsequent, and that way they can keep track of any damage to shields from micrometeorites and things of this nature."

FRIDAY, JUNE 14, 2002

The shuttle astronauts used Endeavour's robot arm to detach the Leonardo cargo module from the international space station's Unity module Friday, maneuvering it back into the cargo bay for return to Earth. Endeavour will undock from the station Saturday, setting the stage for landing Monday. Read full story.

The Canadian Space Agency and its major robotics contractor are troubleshooting a software glitch that is preventing the international space station's $600 million robot arm from powering up normally when drawing electricity from a new attachment platform. Read full story.

For Franklin Chang-Diaz, blasting off aboard the shuttle Endeavour for a record-tying seventh space flight was all in a day's work. Taking his first spacewalk was another matter entirely. Asked if the experience was worth the wait, the Costa Rica-born astronaut said "Oh, absolutely, every minute of it." Read full story.

2012 GMT (4:12 p.m. EDT)

The Leonardo module has been returned to Endeavour's payload bay, latching down at 4:11 p.m. EDT.

1635 GMT (12:35 p.m. EDT)

Endeavour astronaut Philippe Perrin has powered up the shuttle's robotic arm to grapple the Leonardo cargo module. The Italian-built moving van was launched aboard Endeavour to deliver nearly three tons of supplies and equipment to the International Space Station. But today it's time to detach the module from the Unity connecting node and return it to the shuttle's payload bay for the trip back to Earth. The astronauts have filled Leonardo with more than two tons of trash and other unneeded items from the station.

THURSDAY, JUNE 13, 2002

Two spacewalking surgeons operated on the international space station's $600 million robot arm Thursday, bolting on a replacement joint to fix what amounts to a broken wrist. Endeavour astronauts Franklin Chang-Diaz and Philippe Perrin completed a seven-hour, 17-minute spacewalk. Read full story.

2234 GMT (6:34 p.m. EDT)

With the spacewalkers back in the Quest airlock, repressurization began at 6:33 p.m. EDT, marking the end of today's seven-hour, 17-minute EVA.

2216 GMT (6:16 p.m. EDT)

Now seven hours into the spacewalk. It is nearing completion after the spacewalkers wrap up the clean up and tool inventory activities, which are still continuing.

The arm checkout, meanwhile, has resumed.

2131 GMT (5:31 p.m. EDT)

The arm checkout has been stopped until after the spacewalkers finish their clean up and equipment moving work around the arm.

2116 GMT (5:16 p.m. EDT)

Checkout of the arm still progressing well.

2105 GMT (5:05 p.m. EDT)

Expedition 4 astronaut Dan Bursch reports the robotic arm is operational in its primary control string as the checkout continues. The problem with the old wrist joint occurred on the secondary string.

2050 GMT (4:50 p.m. EDT)

The spacewalkers are now working to clean up their worksite on the Destiny module and put away tools. They will continue with these chores and position some equipment for the next station assembly mission before returning to the airlock to complete this third and final spacewalk of Endeavour's mission.

2040 GMT (4:40 p.m. EDT)

Mission Control reports the robot arm tests have gone well so far! The station crew has now been given a "go" to continue with the more thorough checkout.

The spacewalkers, meanwhile, have bolted the old joint to the carrier and are working now to install that thermal cover over it.

2034 GMT (4:34 p.m. EDT)

This launch carrier provides power to the joint for heaters to keep the unit stable for its journey back home. Once everything is hooked up, the spacewalkers will put a thermal cover over the joint -- the same cover that was over the new joint for launch.

2021 GMT (4:21 p.m. EDT)

Spacewalkers are still working to bolt the faulty joint to the payload bay wall carrier.

2016 GMT (4:16 p.m. EDT)

Now five hours into this spacewalk.

Mission Control reports that a 30-minute warmup period is underway on the Canadian arm before a checkout can begin following the surgery today to replace it's broken wrist joint. The replacement by the two spacewalkers appeared to go very well.

2009 GMT (4:09 p.m. EDT)

The spacewalkers continue working to secure the old joint to the carrier in the payload bay of Endeavour for return to Earth for analysis.

1958 GMT (3:58 p.m. EDT)

Perrin has turned a bolt to engage power, data and video cables inside the arm to mate up with the hand. While controllers power up the arm for a checkout now that this surgery has been completed, the spacewalkers will return to the payload bay to put the old joint into the launch carrier that the new joint rode into space on.

1955 GMT (3:55 p.m. EDT)

The Latching End Effector -- the hand of the space station's robotic arm -- has been completely reattached. The spacewalkers tightened six bolts to make the secure connection.

1940 GMT (3:40 p.m. EDT)

Bolting of the hand to finish putting the station's Canadarm2 back together is underway.

1936 GMT (3:36 p.m. EDT)

The hand has been joined to the wrist roll joint. Bolting will now begin.

1931 GMT (3:31 p.m. EDT)

The arm's hand has been removed from its storage location. The spacewalkers will work in tandem to align it to the new wrist roll joint for attachment.

Performing the same steps as installation of the new joint, they will tighten six bolts in stages to secure the hand to the rest of the arm. Then the power, video and data cables will be reconnected.

1927 GMT (3:27 p.m. EDT)

The spacewalkers are now moving over to pick up the robotic arm's hand, which was removed so the wrist joint could be replaced. The hand has been stowed on the side of the Destiny module during the wrist work.

1923 GMT (3:23 p.m. EDT)

Mission Control reports that the spacewalk is virtually back on the timeline after getting behind earlier today. The spacewalk has passed the four-hour mark.

1921 GMT (3:21 p.m. EDT)

The new joint is now completely bolted to the rest of the robotic arm. Perrin will now turn a separate bolt to re-engage the power, data and video lines to the new joint.

1919 GMT (3:19 p.m. EDT)

The spacewalkers are now in the third stage of tightening the bolts.

1914 GMT (3:14 p.m. EDT)

The initial stage of torquing the bolts has been completed. Second phase of tightening is starting.

1909 GMT (3:09 p.m. EDT)

The spacewalkers are using their power tools to drive the six bolts around the joint's circumference that hold the joint to the rest of the arm.

1903 GMT (3:03 p.m. EDT)

Joint is now being mated to the arm.

1901 GMT (3:01 p.m. EDT)

So far so good.

The spacewalkers are lining up the new wrist roll joint for its attachment to the arm's yaw joint. Once connected, they will tighten six fasteners to firmly secure the joint to the arm. Perrin will then turn a bolt to engage the power, video and data cabling from the rest of the arm to the new joint.

1857 GMT (2:57 p.m. EDT)

Arm power is now off and controllers have given the crew a "go" to install the new joint.

As Perrin rides the shuttle's arm back up to the station's arm, Chang-Diaz is climbing back to the worksite to assist in attaching the joint and bolting it in place.

1855 GMT (2:55 p.m. EDT)

The station's arm is being powered down again in preparation for attachment of the new joint. "Keep-alive" power was applied to the arm while the spacewalkers were down in the payload bay.

1854 GMT (2:54 p.m. EDT)

The wrist roll joint is now free from the shuttle's payload bay, in the hands of Perrin to be carried up to the station's robotic arm for installation.

1852 GMT (2:52 p.m. EDT)

Perrin, riding on the end of the shuttle's robotic arm, is holding the new joint as fellow spacewalker Chang-Diaz releases the final bolt keeping the joint attached to its launch carrier.

1843 GMT (2:43 p.m. EDT)

Unbolting of the new joint from the payload bay carrier is underway.

1837 GMT (2:37 p.m. EDT)

With the old joint in its temporary stowage location next to the new joint, the spacewalkers will now remove a thermal blanket covering the replacement joint and then release the six fasteners holding it to the launch carrier on the side wall of Endeavour's payload bay.

1823 GMT (2:23 p.m. EDT)

The "go" has been given to re-apply "keep-alive" power to the robotic arm so its heaters can operate.

1821 GMT (2:21 p.m. EDT)

The faulty wrist roll joint of the station's Canadarm2 has been removed. It will be placed in the payload bay of the shuttle, ultimately taking the stowage location that the new joint was launched in. Engineers want this old joint returned to Earth for analysis.

1818 GMT (2:18 p.m. EDT)

The final bolt is now being loosened by Chang-Diaz. Perrin has the joint tethered to himself in preparation for carrying the unit down to Endeavour's payload bay.

1812 GMT (2:12 p.m. EDT)

The cabling has been unhooked and the spacewalkers are working in tandem to release the six Expandable Diameter Fasteners that hold the wrist joint to the rest of the arm.

1810 GMT (2:10 p.m. EDT)

Perrin will turn a bolt to release the power, video and data cabling between the wrist roll joint and the rest of the arm -- a similar job to one he did a short time ago before removing the arm's hand.

1803 GMT (2:03 p.m. EDT)

The hand has been secured to the hull of the Destiny module by the spacewalkers.

1754 GMT (1:54 p.m. EDT)

The Latching End Effector (LEE), or hand, of the International Space Station's Canadian-made robotic arm is now separated from the rest of the crane. The 500-pound, washing machine-sized LEE is now in the hand of spacewalker Philippe Perrin. Riding on the shuttle's robotic arm, Perrin will mount the hand to the side of the Destiny module while the wrist joint is replaced.

1751 GMT (1:51 p.m. EDT)

With Perrin holding the arm's hand to keep it stable, Chang-Diaz is now loosening the last fastener.

1748 GMT (1:48 p.m. EDT)

Final unbolting is underway.

1742 GMT (1:42 p.m. EDT)

The spacewalkers are now working together to loosen the six Expandable Diameter Fasteners -- the special type of bolts that hold the hand to the rest of the arm. Chang-Diaz is working on bolt No. 2; Perrin on No. 5.

1738 GMT (1:38 p.m. EDT)

Perrin has used his power tool to turn a bolt on that arm that disengages the power, data and video cabling in the interface between the wrist roll joint and hand.

1736 GMT (1:36 p.m. EDT)

Mission Control confirms the arm is powered down, clearing the way for the spacewalkers to begin the steps to remove the arm's hand.

1731 GMT (1:31 p.m. EDT)

With the robotic arm now properly positioned for it's high-flying repair today, the "go" has been give from the crew to the ground to power down the arm in advance of the hand's removal.

Once the arm is safed, Perrin will then disconnect power, data and video cabling between the hand and wrist roll joint. Once that is completed, six bolts will be loosened to permit the hand to separate from the joint and rest of the arm. With the joint exposed, the spacewalkers can remove that faulty unit and install a new one.

1721 GMT (1:21 p.m. EDT)

The hand of the arm is now being rolled into position for it's removal, giving the spacewalkers the best access. The thermal covers have been put in place by Perrin.

1717 GMT (1:17 p.m. EDT)

The spacewalkers have received encouraging words from the crew inside that even though the set up activities too much longer than planned today, the time can be made up as the repair work gets underway.

1712 GMT (1:12 p.m. EDT)

In preparation for removing the hand of the station's arm, Perrin must first install thermal covers of the television camera and lights on the end effector. These blankets will ensure the hardware won't get too cold while the hand is unpowered and removed.

1700 GMT (1:00 p.m. EDT)

Perrin, tangled up with a tether or two, has finally managed to get into the shuttle foot platform. The spacewalk is nearing the two-hour mark. The set up work finally appears to be nearing completion now.

1645 GMT (12:45 p.m. EDT)

The station arm has now been maneuvered into position by Chang-Diaz. For today's work Chang-Diaz is standing on a foot platform attached to the hull of the Destiny module and Perrin is riding on the end of Endeavour's robotic arm.

1640 GMT (12:40 p.m. EDT)

This is the 41st spacewalk devoted to space station assembly, the 16th staged from the lab complex itself and the ninth to utilize the U.S. Quest airlock module. Going into today's excursion, 31 Americans, one Canadian, one Frenchman and five Russian cosmonauts had logged 248 hours and 41 minutes of spacewalk time putting the station together.

1632 GMT (12:32 p.m. EDT)

The station arm is now moving back into position for today's repair.

1616 GMT (12:16 p.m. EDT)

Now one hour into this scheduled seven hour spacewalk.

1611 GMT (12:11 p.m. EDT)

The spacewalkers are still working to get their foot platform and other equipment positioned and ready for the arm repair. The crew is moving the arm away from the worksite to give the spacewalkers more room to get situated and not to bump into the space crane.

1556 GMT (11:56 a.m. EDT)

The spacewalkers continue their set up chores, positioning the equipment needed for today's work.

1540 GMT (11:40 a.m. EDT)

This spacewalk was ordered back in March because of a problem experienced with the wrist roll joint of the arm. NASA officials decided the joint, which is designed to be replaced in space, be swapped out to ensure the arm is healthy for the continued construction of the International Space Station.

Specifically, the problem prevents the brakes on the arm from being released when running on the secondary control mode.

Today's work will occur in the payload bay of Endeavour, near the underside of the Destiny laboratory module. The replacement joint is housed on a carrier plate in the bay. The old joint will be mounted to the plate for return to Earth where engineers will perform an analysis to determine exactly what caused the trouble in orbit.

The spacewalkers are currently getting situated and preparing to begin this arm surgery in space.

1528 GMT (11:28 a.m. EDT)

"It's true, this is a critical EVA, we need that arm working for the rest of station assembly," Perrin said Wednesday during a crew news conference. "But actually, it's a very simple EVA. It may be a little bit longer than the two others, but the first two EVAs prepared us very well and we feel extremely confident. The hardware is really well designed, thanks to the Canadian Space Agency, and we are fully confident."

1516 GMT (11:16 a.m. EDT)

EVA BEGINS. Franklin Chang-Diaz, on his seventh spaceflight, and rookie French astronaut Philippe Perrin officially began their third spacewalk at 11:16 a.m. EDT today as they switched their spacesuits from station-fed power to internal batteries.

Today's seven-hour excursion will see the free hand of the space station's robotic arm removed so the broken wrist-roll joint can be replaced. The hand then will be reattached, returning the arm to full working order. The arm is critical to continued assembly of the orbiting outpost.

1512 GMT (11:12 a.m. EDT)

Depressurization of the space station's Quest airlock is now complete. It turned out that one valve was not opened as it was supposed to be, which slowed down the depress today. The spacewalk start time will be clocked when Chang-Diaz and Perrin switch their suits to battery power.

1502 GMT (11:02 a.m. EDT)

The pressure is now down to 1.6 psi.

1452 GMT (10:52 a.m. EDT)

Depressurization of the airlock should be completed very shortly.

1424 GMT (10:24 a.m. EDT)

Static from the communications system on Franklin Chang-Diaz's spacesuit has delayed the start of today's spacewalk. The astronauts have been troubleshooting the situation and trying to improve quality of transmissions. Flight controllers suspect that perhaps a bit of water from Chang-Diaz's drink bag could have spilled and caused the problem.

In any event, Mission Control says the audio quality is acceptable and has given a "go" to begin depressurizing the Quest airlock. That will begin momentarily.

THURSDAY, JUNE 13, 2002

Two spacewalking surgeons will operate on the international space station's $600 million robot arm Thursday, bolting on a replacement joint to fix what amounts to a broken wrist. Endeavour astronauts Franklin Chang-Diaz and Philippe Perrin will begin the third and final spacewalk of this shuttle mission around 10:43 a.m. EDT. The excursion is expected to last seven hours.

Below is an overview of the spacewalk from our mission preview report:

First, the spacewalkers will put a thermal blanket around the arm's latching end effector - the LEE - the part of the arm that actually locks on to components and grapple fixtures. The arm then will be powered down and Perrin will disconnect the LEE's internal power cable.

After loosening six expandible diameter fasteners, or EDFs, holding the 450-pound LEE onto the wrist-roll joint, the spacewalkers will remove the end effector and temporarily stow it on a nearby spacewalker foot restraint.

The faulty wrist-roll will be removed in similar fashion, that is, after loosening six EDFs and disconnecting an internal power cable. The replacement joint, which measures about two feet by two feet and weighs some 220 pounds, will be installed by tightening the six EDFs with 25 foot pounds of torque each and making the single required electrical connection. That will clear the way for reattachment of the latching end effector.

At that point, ground controllers plan to power the arm back up and begin a series of tests while Perrin and Chang-Diaz move the old wrist-roll joint from its temporary stowage point in the cargo bay to the fixture used to hold the new joint in place during launch.

"We in EVA never like to think of our tasks as simple," said lead spacewalk planner Tricia Mack. "But it is a straightforward EVA if all the hardware works correctly.

"I guess what's complex about it is the timing," she said. "We will be powering the arm up in between, after we remove the end effector and the wrist roll joint, when the crew's in the bay working and safely away from the work site, we will power the arm up to protect some of the components on it that would normally be without power. So there's a lot of commanding between the ground, the station crew and obviously the EVA crew. I wouldn't say it's simple, but you're right, as long as the hardware works it'll be pretty straightforward."

And what will the crew do if one of the expandible diameter bolts fails to collapse when the spacewalkers loosen the central bolt?

"We have a long list of contingencies we've trained for," Mack said. "If we have a faulty EDF, we are flying a spare. ... If the clevis and lug interface wouldn't come apart, we have a contingency plan - and I hate saying this because I know the Canadians don't like it - but we have a pry bar on the space station that we maybe could use to give it a little help coming apart."

Five of the six EDFs in the latching end effector and the replacement wrist-roll joint must be fully engaged for normal arm operation.

"It's going to be a long EVA, because we have a lot of bolts to deal with, unbolting and rebolting them," Perrin said. "But as far as the hardware we need to change, it's pretty simple.

"It looks like major surgery because we're going to take the end of the arm out and then swap the joint and then get the LEE back in place and we have to run against the clock and do everything in an orderly and timely fashion," he said. "It's going to be a long EVA, but I think quite simple. ... I feel very confident about the amount of training we've had."

WEDNESDAY, JUNE 12, 2002

To understand what's it's like to make a long-duration voyage aboard the international space station, imagine taking a really long trip in a car. And then imagine never getting a chance to stop or step outside, even if your traveling companion is driving you up the wall. Read full story.

TUESDAY, JUNE 11, 2002

Franklin Chang-Diaz and Philippe Perrin made their second spacewalk today, stepping outside the International Space Station for a five-hour excursion to bolt in place and wire up the new mobile base for outpost's Canadian robotic arm. Read full story.

2023 GMT (4:23 p.m. EDT)

Repressurization of the Quest airlock began at 4:20 p.m. EDT, marking the official end of today's five-hour spacewalk by Chang-Diaz and Perrin. The spacewalk went so well that all the work planned was completed about 90 minutes ahead of schedule.

2016 GMT (4:16 p.m. EDT)

The airlock hatch is now closed.

2010 GMT (4:10 p.m. EDT)

The spacewalkers are now back in the airlock, preparing to end this spacewalk.

1924 GMT (3:24 p.m. EDT)

The spacewalkers have tied a bag to the Mobile Base System. Inside the bag is emergency cabling that would be used in the future to provide power to the station's robotic arm in the event of a malfunction that stalled the Mobile Transporter between work site power sockets on its railway.

The spacewalkers will now snap some photos for documentation purposes and begin cleaning up to bring the EVA to a conclusion.

1920 GMT (3:20 p.m. EDT)

Now four hours into this incredibly smooth spacewalk by Franklin Chang-Diaz and Philippe Perrin. Their next job is to attach a bag to the Mobile Base System that contains an emergency extension cable. That will be the final major task of this EVA.

1911 GMT (3:11 p.m. EDT)

Camera installation is now complete. The crew has given flight controllers a "go" to power up the camera and video distribution system for a checkout.

1904 GMT (3:04 p.m. EDT)

Chang-Diaz has removed the camera from its original location and Perrin will now bolt it to the mast.

1854 GMT (2:54 p.m. EDT)

The spacewalkers are beginning the work to relocate the camera from its position on the keel of the Mobile Base System to the camera mast that was deployed earlier today.

1850 GMT (2:50 p.m. EDT)

Now three hours and 30 minutes into this spacewalk.

1838 GMT (2:38 p.m. EDT)

The Mobile Base System is now permanently mounted to the Mobile Transporter railcar. The spacewalkers have secured four bolts to join the two structures together, completing the work to connect the newly-delivered MBS to its home on the station.

The two primary jobs left in today's spacewalk -- deploying a camera and attaching a cable bag to the MBS.

1825 GMT (2:25 p.m. EDT)

The umbilicals have been engaged; power is now flowing to the MBS. This confirms the cable connections made by the spacewalkers earlier today were made properly. Meanwhile, the spacewalkers have secured two of the four bolts.

1815 GMT (2:15 p.m. EDT)

The spacewalkers now turn their attention to physically bolting the Mobile Base System to the Mobile Transporter. A capture claw is currently holding the two structures together. The four bolts the spacewalkers will secure will allow the no-longer-needed claw to be opened.

1810 GMT (2:10 p.m. EDT)

The umbilical mechanisms are now driving to engage the bottom of the Mobile Transporter to relay power to the Mobile Base System.

1807 GMT (2:07 p.m. EDT)

The spacewalkers have tightened the bolts to hold the POA and camera mast into place.

1758 GMT (1:58 p.m. EDT)

Perrin is now working on a camera mast on the other side of the Mobile Base System.

1755 GMT (1:55 p.m. EDT)

The boom-like POA has now been rotated out. Chang-Diaz will now bolt it into place.

1753 GMT (1:53 p.m. EDT)

The spacewalkers are working together now to rotate the POA up and into its deployed position.

1748 GMT (1:48 p.m. EDT)

Perrin continues to work to release the launch restraint bolt holding the POA in its stowed position on the Mobile Base System.

1742 GMT (1:42 p.m. EDT)

Mission Control has elected to have the spacewalkers deploy the Payload Orbital Replacement Unit Accommodation (POA) now and do the umbilical plug-in later. Perrin will unbolt the structure -- which is basically looks and acts as another hand of the Canadian-built robotic arm. In the future, payloads can be attached to the POA and ride along the railway.

Once unbolted, the POA will be rotated out to its deployed position.

1733 GMT (1:33 p.m. EDT)

With the spacewalkers moved out of the area, the crew has given the ground a "go" to engage the umbilicals to begin flowing power through the Mobile Transporter to the Mobile Base System. This will confirm all the cable connections are good.

The next big task of the spacewalk will be the deployment of the Payload Orbital Replacement Unit Accommodation fixture on the Mobile Base System.

1722 GMT (1:22 p.m. EDT)

All of the connnections have now been verified complete as the EVA passes the two-hour mark. The spacewalkers will now go back and check them before moving on to other work.

1715 GMT (1:15 p.m. EDT)

Once the spacewalkers finish with the cable connection work, the Mobile Transporter will be commanded to plug into the umbilical adapter system on the S0 truss railway, thereby feeding power through to the Mobile Base System. The MBS rides atop the MT.

1702 GMT (1:02 p.m. EDT)

Mission Control reports the spacewalkers are now working to connect the second power line to the Mobile Base System.

1653 GMT (12:53 p.m. EDT)

Chang-Diaz is reporting some difficultly routing one of the power cables through a clamp.

1647 GMT (12:47 p.m. EDT)

The video/data cable connection work is nearing completion.

1637 GMT (12:37 p.m. EDT)

Chang-Diaz is now working on the primary power cabling from the Mobile Transporter to the Mobile Base System.

1625 GMT (12:25 p.m. EDT)

The primary video/data cables have been mated. The spacewalkers are now working on the backup cables.

1612 GMT (12:12 p.m. EDT)

Cable connections between the Mobile Base System and Mobile Transporter is now underway. The spacewalkers will hook up two main power cable and four primary and backup video/data cables.

1610 GMT (12:10 p.m. EDT)

The connection of power and data cables to the Mobile Base System can now begin after power to the MBS from the Canadian robotic arm has been switched off.

1606 GMT (12:06 p.m. EDT)

The spacewalkers are now pre-staging cables for upcoming attachment to the mobile base.

1558 GMT (11:58 a.m. EDT)

The "go" has been given to Expedition 4 astronaut Carl Walz to turn off the power feed from the Canadarm2 to the Mobile Base System in preparation for the spacewalkers to mate cables to the MBS.

1553 GMT (11:53 a.m. EDT)

Before the spacewalkers came attach the power and data cables from the Mobile Transporter to the new Mobile Base System, the power feed that is currently flowing from the station's robotic arm to the MBS has to be turned off. The arm has remained grappled to the MBS since lifting the platform out of Endeavour's payload bay two days ago, providing the keep-alive power until today's spacewalk to wire up the Canadian-made MBS. The arm-provided power has kept the MBS' heaters and electronics running.

1545 GMT (11:45 a.m. EDT)

The spacewalkers are making their way to the Mobile Base System, which was mounted to the Mobile Transporter railcar yesterday on the front of the S0 truss of the International Space Station. The first job of this spacewalk will be setting up their equipment to prepare for connecting wiring to the mobile base. The MBS will become the mobile base for the station's Canadian-built robotic arm, allowing the arm to travel the length of the truss backbone on the transporter railcar.

1530 GMT (11:30 a.m. EDT)

Both spacewalkers have made their way out of the Quest airlock.

1520 GMT (11:20 a.m. EDT)

EVA BEGINS. Franklin Chang-Diaz and Philippe Perrin have switched their suits to internal battery power, marking the official start of today's spacewalk at 11:20 a.m. EDT. They will step outside the International Space Station for a six-and-a-half-hour excursion to wire up the new mobile base for outpost's Canadian robotic arm.

1455 GMT (10:55 a.m. EDT)

Depressurization of the Quest airlock continues.

1433 GMT (10:33 a.m. EDT)

The spacewalkers are breathing pure oxygen to purge nitrogen fromtheir blood streams. Work to depressurize the airlock is underway.

1404 GMT (10:04 a.m. EDT)

The crew lock hatch that divides the space station Quest airlock has been closed in preparation for today's outing by spacewalkers Franklin Chang-Diaz and Philippe Perrin.

1320 GMT (9:20 a.m. EDT)

Shuttle astronauts Franklin Chang-Diaz and Philippe Perrin are in the space station's Quest airlock making final preparations for today's spacewalk. They are currently purging their spacesuits before beginning the pre-breathe proceedure.

Watch this page for updates throughout the day!

0220 GMT (10:20 p.m. EDT Mon.)

With the Mobile Base System captured to the space station's new railcar Monday, shuttle astronauts Franklin Chang-Diaz and Philippe Perrin will make another spacewalk Tuesday to wire up the Canadian-made MBS and deploy its appendages. The excursion is due to begin around 11 a.m. EDT.

Scheduled to last six-and-a-half hours, the second EVA of Endeavour's mission will see the astronauts connect four video/data cables and two electrical power lines between the mobile transporter and the MBS. Ground engineers then will power up the MBS through the transporter.

Next, Perrin and Chang-Diaz will deploy the MBS cargo grapple fixture and lock it in place before tightening up four main bolts needed to complete the structural attachment of the MBS to the mobile transporter. Once the bolts are torqued down, ground controllers will command the claw that initially held the MBS in place to retract.

The astronauts will wrap up the spacewalk by repositioning the MBS camera to its operational location and stowing a set of emergency cables that could be used to provide power to the station's robot arm in the event of a malfunction that stalled the mobile transporter between work site power sockets.

MONDAY, JUNE 10, 2002

Expedition 4 commander Yuri Onufrienko turned over the international space station to Expedition 5 commander Valeri Korzun and his two crewmates today in a formal change-of-command ceremony marking the arrival of the station's fifth full-time crew. Read full story.

2315 GMT (7:15 p.m. EDT)

After being delayed several hours, the International Space Station change-of-command ceremony was completed at 7:08 p.m. EDT this evening as the Expedition 5 crew formally took control of the outpost from Expedition 4. The crews actually swapped homes between the station and shuttle last week after docking, but this ceremony was staged for the symbolic handover.

An initial attempt to hold the ceremony was interrupted about five hours ago when a smoke alarm sounded in the Russian Zarya module. Controllers believe dust stirred up by supply transfers tripped the alarm. Although it was just a false alarm, the efforts to reset the system and other activities today put the ceremony on hold.

1304 GMT (9:04 a.m. EDT)

Expedition 4 crew member Carl Walz reports the Mobile Base System is firmly secured to the Mobile Transport on the station's S0 truss.

1252 GMT (8:52 a.m. EDT)

The Mobile Base System has been lowered into position atop the Mobile Transporter railcar and the astronauts are in the processing of closing a large attachment claw to latch it down.

1240 GMT (8:40 a.m. EDT)

Expedition 5 crew members Valeri Korzun and Peggy Whitson are using the space station's robot arm to inch the Mobile Base System into position atop the Mobile Transporter railcar.

SUNDAY, JUNE 9, 2002

A pair of first-time spacewalkers -- shuttle astronauts Franklin Chang-Diaz and Philippe Perrin -- took a Sunday stroll in space to move equipment from shuttle Endeavour's payload bay to the exterior of the International Space Station and ready the Canadian Mobile Base System for attachment to the complex. Read full story.

2315 GMT (7:15 p.m. EDT)

Mission Control reports the Mobile Base System, riding on the end of the station's robotic arm, has arrived in its pre-install position in front of the Mobile Transporter on the S0 truss. It will remain there for the night. Attachment activities planned to begin around 8:15 a.m. EDT Monday. The Mobile Base System, once mounted to the transporter, will become the base for the robotic arm, allowing the arm to move up and down the length of the station's truss backbone, which is required for future assembly work.

2312 GMT (7:12 p.m. EDT)

Our spacewalk statistics page has been updated to reflect today's EVA.

2300 GMT (7:00 p.m. EDT)

Canadarm2 continues to maneuver the Mobile Base System from Endeavour's payload bay to its overnight parking location near the Mobile Transporter railcar on the S0 truss. The mating of MBS to the railcar will occur tomorrow after giving time for the temperatures of the two structures to equalize.

2242 GMT (6:42 p.m. EDT)

Repressurization of the U.S. Quest airlock of the International Space Station has begun, signaling the official conclusion of today's successful spacewalk by Franklin Chang-Diaz and Philippe Perrin. The duo mounted a robot arm grapple fixture to the P6 solar array truss, a bundle of debris shields to the station's hull for later installation on the Zvezda service module and prepped the Mobile Base System to be unberthed from the payload bay.

2234 GMT (6:34 p.m. EDT)

The airlock's outer hatch is closed and locked.

2227 GMT (6:27 p.m. EDT)

Now passing the seven-hour mark of this planned six-hour spacewalk. Chang-Diaz and Perrin are climbing back into the station's Quest airlock to bring the EVA to an end.

Meanwhile, the Mobile Base System is being lifted out of Endeavour's payload bay by the station's robotic arm.

2206 GMT (6:06 p.m. EDT)

The spacewalkers have completed their work on the Mobile Base System and are checking they have all their gear before returning to the airlock. Shuttle Commander Ken Cockrell has been given a go to release the latches holding down the MBS in the payload bay once the spacewalkers are clear of the area.

2134 GMT (5:34 p.m. EDT)

With the Mobile Base System connected to station power through the robot arm, the two spacewalkers are working to remove thermal insulation blankets that protected crucial components while the MBS was in the payload bay.

2124 GMT (5:24 p.m. EDT)

Flight controllers report that the space station's robot arm has hooked up its power umbilicals to the Mobile Base System and is now supplying power to its heaters and other systems.

2117 GMT (5:17 p.m. EDT)

The station arm has attached to the Mobile Base System grapple fixture. It will take about five minutes for umbilicals in the arm to deliver "keep alive" power to the MBS.

2106 GMT (5:06 p.m. EDT)

The station arm is closing in on the Mobile Base System grapple fixture. The spacewalk is currently running about 50 minutes behind schedule.

2055 GMT (4:55 p.m. EDT)

Peggy Whitson is maneuvering the robot arm into position to grapple the Mobile Base System in the shuttle's payload bay.

2018 GMT (4:18 p.m. EDT)

Perrin is preparing to thermal blankets that kept the Mobile Base System at the correct temperature in the shuttle's payload bay. Chang-Diaz will join him in this task which is expected to take about 90 minutes.

1943 GMT (3:43 p.m. EDT)

The station robot arm is moving Chang-Diaz to a point where he can step off the arm, freeing it for the next major task of the day, the grapple of the Mobile Base System or MBS.

1938 GMT (3:38 p.m. EDT)

Chang-Diaz is now taking photographs of the station's Control Moment Gyro No.1 which failed on Saturday. Flight controllers want to check that the device did not suffer any external damage.

1935 GMT (3:35 p.m. EDT)

Chang-Diaz has attached the debris shields to a storage location on PMA-1.

1919 GMT (3:19 p.m. EDT)

Chang-Diaz, perched on the station arm, is approaching the storage point on PMA No.1 for the debris shields.

1855 GMT (2:55 p.m. EDT)

Chang-Diaz, riding the station's robot arm, is lifting the debris panels out of the shuttle's payload bay to a storage point on Pressurized Mating Adapter (PMA) No.1.

1840 GMT (2:40 p.m. EDT)

Chang-Diaz has attached a tether to the bundle of debris panels stowed near the aft bulkhead of Endeavour's cargo bay and is working to release them from the payload bay.

1820 GMT (2:20 p.m. EDT)

Spacewalker Philippe Perrin has attached a foot restraint to the Destiny lab, while Whitson and Korzun continue to steer Chang-Diaz into position on the station's robot arm to collect debris panels from the shuttle's cargo bay.

1809 GMT (2:09 p.m. EDT)

Chang-Diaz, riding the station's robot arm, is returning to the payload bay to collect a package of debris shields that will be attached to the Russian Zvezda service module during a future spacewalk by the space station crew. Expedition 5 crew members Peggy Whitson and Valeri Korzun are operating the station arm from within the Destiny laboratory module.

1737 GMT (1:37 p.m. EDT)

The Power and Data Grapple Fixture has been installed to the P6 solar array truss by Costa Rican-born astronaut Franklin Chang-Diaz and Philippe Perrin of the French space agency. The fixture will serve as a hand hold for the station's robotic arm later in the construction of the complex to move the P6 truss from it's current location atop the Unity node and Z1 truss to the main truss backbone next year.

The next major event planned in this spacewalk will be the transfer of a package of debris shields from Endeavour's payload bay to the PMA-1 docking adapter. The spacewalkers will secure the shields to the port for a future EVA that will actually install the panels to the hull of the Russian Service Module.

1727 GMT (1:27 p.m. EDT)

Now two hours into the spacewalk. Work to bolt the grapple fixture in place continues.

1715 GMT (1:15 p.m. EDT)

Chang-Diaz has arrived at the P6 truss and the spacewalkers are now working together to mount the grapple fixture.

1643 GMT (12:43 p.m. EDT)

Riding on the end of the station's arm, Chang-Diaz is hand-carrying the grapple fixture to its installation spot on the P6 solar array truss. The fixture -- a round plate -- will be used by the arm to move the truss later in the assembly sequence. Perrin is in position at P6 to assist in attaching the fixture.

1640 GMT (12:40 p.m. EDT)

The grapple fixture is now free of the carrier on the side of the payload bay.

1630 GMT (12:30 p.m. EDT)

While Chang-Diaz works to unbolt the grapple fixture from its launch carrier, Perrin has made his way from the PMA-1 to the P6 to prepare for the fixture's upcoming installation.

1622 GMT (12:22 p.m. EDT)

After the long ride from the station airlock to the aft portion of Endeavour's payload bay, Chang-Diaz has finally arrived at the Power and Data Grapple Fixture to begin releasing it for the upcoming relocation to the P6 solar array truss.

1605 GMT (12:05 p.m. EDT)

While Chang-Diaz rides on the station's robotic arm today, Perrin is designated as the "free-floater" meaning he will be moving around the station and shuttle exterior by hand. The first task for Perrin is climbing to the docking adapter (PMA-1) between the U.S. Unity node and Zarya module to install a receptacle in preparation for attachment of the Service Module debris shielding later today. Meanwhile, Chang-Diaz is headed for the payload bay to prepare for detaching the grapple fixture from the sidewall for it's mounting to the station's P6 truss.

1557 GMT (11:57 a.m. EDT)

Now a half-hour into today's spacewalk. Chang-Diaz and Perrin, working just outside the Quest airlock, are setting up the equipment for this EVA, including the installation of a foot restraint on the end of the station's robotic arm. Chang-Diaz will stand on the platform and be maneuvered around by the arm during much of the spacewalk.

1527 GMT (11:27 a.m. EDT)

A pair of first-time spacewalkers have begun a Sunday stroll in space to move equipment from shuttle Endeavour's payload bay to the exterior of the International Space Station and ready the Canadian Mobile Base System for attachment to the complex. Shuttle astronauts Franklin Chang-Diaz and Philippe Perrin began their six-hour spacewalk at about 11:27 a.m. EDT.

During today's spacewalk, Franklin Chang-Diaz and Philippe Perrin will install a robot arm grapple fixture to the station's P6 solar array truss so the structure can be moved later in the assembly sequence and stow a package of debris shields to the hull of the Russian Service Module for installation in the future.

They will also prepare the Mobile Base System, riding in Endeavour's payload bay, for its unberthing by the station's arm this afternoon and planned Monday attachment to the outpost's Mobile Transporter on the front of the S0 truss. The spacewalkers will remove thermal covers from the MBS after the station's arm has grappled the structure today and begins flowing keep-alive power. The Mobile Base System will allow the Canadian-built arm to travel the length of the station's eventual 356-foot truss backbone.

One additional job that has been added to the timeline today calls for Chang-Diaz to visually inspect the Control Moment Gyros on the Z1 truss to ensure yesterday's failure of one gyro was indeed self-contained. Flight controllers want the spacewalk to look and make sure the gyro's bearing failure did not cause any external damage to the surrounding area.

1524 GMT (11:24 a.m. EDT)

The spacewalkers are now opening the external hatch on the Quest airlock. The EVA will officially begin when they switch their suits from station power to internal battery power.

1518 GMT (11:18 a.m. EDT)

The airlock pressure is now less than one psi. The spacewalk will begin momentarily.

1445 GMT (10:45 a.m. EDT)

The space station's Quest airlock is now being depressurized in readiness for today's spacewalk.

1430 GMT (10:30 a.m. EDT)

Endeavour astronauts Franklin Chang-Diaz and Philippe Perrin are in the final stages of their pre-breathe activities prior to the start of today's spacewalk. The astronauts are breathing pure oxygen to purge nitrogen from their blood streams, a proceedure necessary to prevent the spacewalker suffering from the "bends".

0300 GMT (11:00 p.m. EDT Sat.)

The shuttle and station crews opened up the Leonardo module Saturday and began unloading its 5,600 pounds supplies and equipment. The cargo van was attached to the Unity node of the station at 10:28 a.m. EDT, and at about 5:30 p.m. the hatch was opened. Expedition 4 astronaut Dan Bursch reported at 5:52 pm that all crew members had entered the logistics module and were working to get the transfers rolling.

Meanwhile, preparations were made Saturday for Endeavour astronauts Franklin Chang-Diaz and Philippe Perrin to make a six-hour spacewalk Sunday, the first of three scheduled for the shuttle's mission. The EVA is due to begin around 11 a.m. EDT.

From our mission preview report, here is an overview of the spacewalk and its objectives:

This will be the 39th space station assembly spacewalk, the 14th staged from the station itself and the sixth from the U.S. Quest airlock module. Chang-Diaz and Perrin are the 37th and 38th individuals to participate in a station assembly spacewalk.

Going into Endeavour's mission, 30 Americans, one Canadian and five Russian cosmonauts had logged 236 hours and 27 minutes of spacewalk time in 38 ISS assembly spacewalks.

The first objective for Perrin and Chang-Diaz during the first spacewalk of Endeavour's mission is to attach a Power, Data and Grapple Fixture (PDGF) on the P6 solar array truss. The grapple fixture will be needed next year when the array is moved from the upward-facing Z1 truss atop the Unity module and mounted on one end of the main solar array truss currently under construction.

Chang-Diaz, wearing a spacesuit with red stripes, will be anchored to the end of the shuttle's 50-foot-long robot arm for most of this first spacewalk while Perrin will be the designated "free floater."

The second objective of the spacewalk is to remove the micrometeoroid debris shields form the shuttle's cargo bay and temporarily stow them on the pressurized mating adapter, or PMA, between Unity and the Russian Zarya module. As already mentioned, the debris shields will be deployed in late July by Whitson and Korzun.

Designed and built by the Russians, the six debris shields weigh about 100 pounds altogether. They are the first in a set of about two dozen panels that ultimately will be installed on the Zvezda module. When fully deployed, the complete set of panels will reduce the odds of a micrometeoroid strike that could penetrate the module's hull by about 1 percent.

While Perrin and Chang-Diaz work to transfer and stow the debris shields, Whitson and Walz, working at a control station inside the Destiny module, will lock the station's robot arm on the MBS, still mounted in the shuttle's cargo bay. The robot arm will provide the "keep-alive" electrical power to operate critical heaters inside the MBS until it can be attached to the mobile transporter the next day.

After the arm is attached and keep-alive power is flowing to the MBS, Chang-Diaz and Perrin will remove no-longer-needed thermal covers before re-entering the station's airlock. The station arm then will pull the MBS from the cargo bay and move it to a point about six feet away from the mobile transporter where it will remain overnight.

On Monday, Walz and Whitson will drive the MBS down onto the mobile transporter cart and engage a mechanical claw that will temporarily lock the platform in place. On Tuesday, Chang-Diaz and Perrin will stage a second spacewalk to complete the attachment.

Watch this page for periodic updates on the spacewalk beginning with the start of the excursion around 11 a.m. EDT.

SATURDAY, JUNE 8, 2002
1530 GMT (11:30 a.m. EDT)

Engineers at the Johnson Space Center in Houston are troubleshooting an apparent failure in one of the four powerful control moment gyroscopes, or CMGs, that help keep the international space station properly oriented. Read full story.

1515 GMT (11:15 a.m. EDT)

Shuttle commander Kenneth Cockrell, operating Endeavour's 50-foot-long robot arm, pulled a $150 million cargo module from the orbiter's payload bay this morning and successfully attached it to a downward-facing port on the international space station's Unity module. Read full story.

0130 GMT (9:30 p.m. EDT Fri.)

The Expedition 5 crew's stay on the International Space Station at 6:55 p.m. EDT Friday when their custom-made Soyuz return capsule seat liners and Russian entry suits were transferred from Endeavour to the station. Expedition 5 is led by Russian commander Valeri Korzun with flight engineers Peggy Whitson and Sergei Treschev.

With that transfer complete, Expedition 4's Yuri Onufrienko and flight engineers Dan Bursch and Carl Walz formally concluded their 182-day stay as space station residents. They will ride home aboard Endeavour.

The shuttle and station crews are now in planned sleep period. They are due to be awakened at 5:23 a.m. EDT Saturday for a day that will see the Leonardo cargo module lifted from Endeavour's payload bay and attached to the station and handover briefings between the Expedition 4 and 5 crews. The station's Quest airlock also will be prepped for Sunday's spacewalk.

FRIDAY, JUNE 7, 2002

The shuttle Endeavour gently docked with the International Space Station Friday as the two spacecraft sailed along a southeasterly trajectory over the Pacific Ocean approaching New Zealand. Meanwhile, engineers this evening were assessing an apparent problem with the shuttle Endeavour's flash evaporator cooling system. Read full story.

1927 GMT (3:27 p.m. EDT)

The hatchway between the space shuttle Endeavour and the International Space Station is open. All 10 astronauts are now together and beginning their busy timeline of joint work. On tap today will be transferring some initial supplies and equipment into the station from the shuttle. And the activities to exchange the station's resident crew will begin.

1900 GMT (3:00 p.m. EDT)

Final preparations to open the hatchway is now underway.

1827 GMT (2:27 p.m. EDT)

The astronauts continue moving through their checklist to prepare for hatch opening between Endeavour and the station. No significant problems have been reported.

1737 GMT (1:37 p.m. EDT)

Before the hatch opening the astronauts have to complete a series of leak and pressure checks.

1727 GMT (1:27 p.m. EDT)

The docking ring has been fully retracted and the hooks and latches have engaged to tightly seal the shuttle to the space station, Mission Control reports.

1723 GMT (1:23 p.m. EDT)

Ring retraction is underway and Mission Control reports good alignment thus far.

1719 GMT (1:19 p.m. EDT)

Endeavour astronaut Frank Chang-Diaz reports the second try at retracting the docking ring will now begin. The ring must be retracted into the shuttle's docking system in order to create a firm seal between the two spacecraft.

1707 GMT (1:07 p.m. EDT)

The shuttle's docking ring has been extended again to allow the motions to damp out for the next several minutes before retraction is attempted again.

1654 GMT (12:54 p.m. EDT)

Mission Control has given the shuttle crew a "go" to fully re-extend the docking ring, do a "force align" and then try to retract the ring again.

1645 GMT (12:45 p.m. EDT)

The docking ring retraction has been stopped part way through to allow more oscillations to damp out between Endeavour and the station.

1638 GMT (12:38 p.m. EDT)

After waiting a few minutes for the oscillations to damp out, the docking ring alignment has now occurred. The approval has been given by Mission Control for the shuttle crew to press on with the post-docking activities.

1625 GMT (12:25 p.m. EDT)

CONTACT AND CAPTURE! Space shuttle Endeavour has arrived at the International Space Station for an eight-day visit. Docking occurred at 12:25 p.m. EDT.

The shuttle has ferried the three-person Expedition 5 crew -- commander Valeri Korzun, Peggy Whitson and Sergi Treschev -- to the orbiting outpost to begin their four-month stay. The current station resident crew -- Expedition 4's Yuri Onufrienko Carl Walz and Dan Bursch -- will ride Endeavour home to complete a voyage of over six months.

Endeavour will also deliver supplies, experiments and the Mobile Base System for the station's Canadian-built robotic arm. Three spacewalks are planned during the shuttle's stay.

The relative motions of the shuttle and station will be allowed to damp out over the next few minutes by the spring-loaded docking system. Later, the hooks and latches will be closed to firmly join the two craft and Endeavour's Orbiter Docking System docking ring will be retracted to form a tight seal.

The opening of hatches between the station and shuttle is expected in about two hours.

1624 GMT (12:24 p.m. EDT)

Final feet to docking.

1623 GMT (12:23 p.m. EDT)

The orientation-control gyros on the station are disabled for the linkup to keep the complex from moving, while Endeavour's thrusters are programmed to fire in a calculated way to force the two docking ports together at the point of contact.

1620 GMT (12:20 p.m. EDT)

The alignment between docking ports on Endeavour and the space station is acceptable and no "fly out" maneuver by the shuttle is necessary. The final approach along the last 30 feet is now in progress.

1618 GMT (12:18 p.m. EDT)

Inside 40 feet.

1617 GMT (12:17 p.m. EDT)

Distance is now 50 feet as Endeavour slowly inches ever closer to the International Space Station under the manual control of commander Ken Cockrell.

1615 GMT (12:15 p.m. EDT)

Endeavour is now 60 feet from the station.

1610 GMT (12:10 p.m. EDT)

Docking will occur a few minutes past the targeted 12:17 p.m. time. There is no window in which the docking must happen. The rendezvous is simply taking a few more minutes than expected.

1605 GMT (12:05 p.m. EDT)

About 170 feet from docking.

1600 GMT (12:00 p.m. EDT)

Distance is now 210 feet, closing at 0.18 feet per second.

1555 GMT (11:55 a.m. EDT)

Endeavour is now 270 feet from the station.

1552 GMT (11:52 a.m. EDT)

The solar arrays on the Russian modules have been feathered for the final approach by the shuttle. Endeavour continues its approach to the station's front docking part along the velocity vector, or V-bar.

1547 GMT (11:47 a.m. EDT)

Endeavour is now in front of the station, in respect to the direction of travel. The shuttle is now less than 400 feet away.

1545 GMT (11:45 a.m. EDT)

Mission Control has given the Endeavour crew a "go" for docking.

1543 GMT (11:43 a.m. EDT)

Now inside 430 feet from docking port to docking port.

1540 GMT (11:40 a.m. EDT)

Endeavour continues the trek from below the station to a point directly in front of the orbiting complex. Distance between the two spacecraft is 500 feet.

1532 GMT (11:32 a.m. EDT)

With Endeavour 600 below the station, the shuttle is beginning the maneuver to fly from the point beneath the complex to a point in front.

1528 GMT (11:28 a.m. EDT)

Endeavour is reaching the milestone point directly feet below the space station. Commander Ken Cockrell is taking over manual control for the remainder of today's rendezvous and docking of Endeavour to the International Space Station.

Piloting the shuttle from the aft control station on the flight deck of Endeavour, he will regularly pulse the shuttle's steering jets to keep the shuttle on the correct course.

The shuttle will make an arc from the point below to a point in front of the space station before beginning the final approach. Docking at the front of the station -- to the Destiny module -- is scheduled for 12:17 p.m. EDT.

1520 GMT (11:20 a.m. EDT)

Inside 1,500 feet, closing at just over two feet per second. About one hour from docking.

The station's solar arrays will soon be "feathered" so they are edge-on to the approaching shuttle. This is done to protect the arrays from the shuttle's thruster plumes. The Russian arrays will be positioned shortly.

1517 GMT (11:17 a.m. EDT)

The shuttle has completed its final course correction maneuver.

1515 GMT (11:15 a.m. EDT)

Endeavour is now 2,500 feet from the station, closing at four feet per second.

1507 GMT (11:07 a.m. EDT)

The shuttle is now inside one mile to the station, closing at about 6 feet per second. Endeavour has just performed another course correction burn. The shuttle can do as many as four of these small maneuvers during the final phase of the rendezvous. The first one was skipped and two have been done.

1457 GMT (10:57 a.m. EDT)

Endeavour is now two miles from the space station. The closure rate is slowing, with the shuttle currently moving in at 12 feet per second.

1447 GMT (10:47 a.m. EDT)

Now 90 minutes from the planned docking time. Endeavour is currently about four miles behind and below the station, still closing at a rate of 17 feet per second. The shuttle is preparing to perform a small course correction maneuver. There are four opportunities allow the final approach to make corrections. The first chance was not required today; this upcoming tweak is the second opportunity.

1435 GMT (10:35 a.m. EDT)

The distance separating the two spacecraft is now measured at six statute miles. Endeavour is closing at a rate of about 17 feet per second.

1428 GMT (10:28 a.m. EDT)

Mission Control reports the International Space Station has completed its maneuver to the proper attitude for today's docking.

1400 GMT (10:00 a.m. EDT)

Endeavour has just completed the Terminal Initiation rocket firing, which puts the shuttle on a trajectory to directly intercept the orbiting International Space Station. The TI burn represents the start of Endeavour's final approach to the station after nearly two days of chasing the complex since launch. Docking is still set for 12:17 p.m. EDT.

0401 GMT (12:01 a.m. EDT)

Space shuttle Endeavour is on course to dock with the International Space Station at 12:17 p.m. EDT today, kicking off a busy eight-day stay to exchange resident crews, perform three spacewalks and deliver supplies and equipment. full story.

THURSDAY, JUNE 6, 2002

Evening status report issued by Mission Control:

Gaining on the International Space Station by 580 statute miles with each 90-minute orbit, Endeavour's crew spent today completing preparations for Friday's scheduled docking with the complex.

With docking scheduled at 12:17 p.m. EDT tomorrow, STS-111 Commander Ken Cockrell, Pilot Paul Lockhart and Mission Specialists Philippe Perrin and Franklin Chang-Diaz today verified all of Endeavour's equipment is ready. Perrin and Chang-Diaz set up a centerline camera Cockrell will use during Friday's final approach to align Endeavour with the station's docking port. They also successfully tested the shuttle docking system and extended it to a position ready for contact with the station.

Cockrell and Perrin activated the shuttle robotic arm and used its cameras to survey the contents of the payload bay. Perrin and Chang-Diaz, who will conduct the three spacewalks scheduled for the mission, successfully checked out the spacesuits they will use during their scheduled spacewalks. During the first two spacewalks, the duo will help install a new aluminum platform, the Mobile Remote Servicer Base System or MBS, atop the station's railcar, the Mobile Transporter. Once installed, the MBS will allow the station's robotic arm, Canadarm2, to travel along the station railway, moving up and down an eventual 300-foot truss for maintenance and assembly work.

Cockrell and Lockhart fired Endeavour's jets three times today to adjust the speed at which the shuttle is closing in on the station. A final Terminal Phase Initiation burn will be conducted Friday morning to begin the final phase of the rendezvous.

The Expedition Four crewmembers -- Commander Yury Onufrienko and Flight Engineers Carl Walz and Dan Bursch -- tidied up their orbital home and completed routine maintenance on the eve of the arrival of the STS-111 crew.

Cockrell and Chang-Diaz took time out today to participate in a live conversation with Costa Rican President Abel Pacheco, U.S. Ambassador to Costa Rica John Danilovich and reporters from Univision and Telemundo. Costa Rican-born Chang-Diaz tied the human spaceflight record yesterday when he launched on his seventh mission.

WEDNESDAY, JUNE 5, 2002

The shuttle Endeavour rocketed into orbit this afternoon, hot on the trail of the international space station for a critical crew exchange and three spacewalks next week to upgrade the lab's robot arm and to fix what amounts to a broken wrist. Read full launch story.

2320 GMT (7:20 p.m. EDT)

Endeavour's clam-shell payload bay doors have been opened, the Ku-band television and radar antenna has been deployed and Mission Control has given its "go" for orbit operations following today's successful launch into space.

2203 GMT (6:03 p.m. EDT)

T+plus 40 minutes, 30 seconds. Endeavour is now in an orbit of 146 by 98 statute miles.

2202 GMT (6:02 p.m. EDT)

T+plus 40 minutes. The twin Orbital Maneuvering System engines on the tail of Endeavour have been fired successfully to propel the shuttle the rest of the way to orbit. No trim required.

The next major event will be opening Endeavour's payload bay doors in about an hour.

2201 GMT (6:01 p.m. EDT)

T+plus 39 minutes. OMS burn is underway.

2159 GMT (5:59 p.m. EDT)

T+plus 37 minutes. The Orbital Maneuvering System engine firing to boost the shuttle from its current sub-orbital trajectory to a safe orbit will occur in about two minutes. The burn will last one minute and two seconds.

2149 GMT (5:49 p.m. EDT)

T+plus 26 minutes, 30 seconds. The two flapper doors on the belly of Endeavour are swinging closed to shield the umbilicals that had connected to the external fuel tank.

2141 GMT (5:41 p.m. EDT)

Today's launch time was 5:22:49.065 p.m. EDT.

2139 GMT (5:39 p.m. EDT)

T+plus 17 minutes. Endeavour's three APU hydraulic-powering units have been shut down. They won't be needed until an entry system checkout on the day before landing, and then again for Endeavour's high-speed return to Earth and touchdown.

2137 GMT (5:37 p.m. EDT)

T+plus 15 minutes. Endeavour has achieved a highly-elliptical sub-orbital trajectory of 139 by 36 statute miles. An Orbital Maneuvering System engine firing in about a half-hour will raise that low point to place the shuttle into a safe orbit.

2136 GMT (5:36 p.m. EDT)

T+plus 14 minutes. The dump of excess propellant from the shuttle's main propulsion system has been completed.

2131 GMT (5:31 p.m. EDT)

T+plus 8 minutes, 52 seconds. The emptied external tank has been jettisoned from the belly of space shuttle Endeavour. The tank will fall back into the atmosphere where it will burn up harmlessly.

2131 GMT (5:31 p.m. EDT)

T+plus 8 minutes, 30 seconds. MECO! Confirmation that Endeavour's main engines have cutoff as planned, completing the powered phase of the launch. Space shuttle Endeavour has safely embarked on its two-day chase to rendezvous and dock with the International Space Station on Friday.

2130 GMT (5:30 p.m. EDT)

T+plus 7 minutes, 30 seconds. The main engines beginning to throttle back to ease the force of gravity on the shuttle and astronauts. Endeavour currently speeding along at 4 miles per second.

2129 GMT (5:29 p.m. EDT)

T+plus 7 minutes. Endeavour can now reach a orbit on the power of one main engine should two fail. But all three continue to fire properly.

2128 GMT (5:28 p.m. EDT)

T+plus 6 minutes. Endeavour now rolling to heads up.

2128 GMT (5:28 p.m. EDT)

T+plus 5 minutes, 25 seconds. Altitude 70 miles, downrange distance 270 miles.

2127 GMT (5:27 p.m. EDT)

T+plus 5 minutes. Endeavour can now reach a orbit on the power of two main engines should one fail. But all three continue to fire properly.

2127 GMT (5:27 p.m. EDT)

T+plus 4 minutes, 20 seconds. Altitude 62 miles, Endeavour 168 miles northeast of the launch pad.

2126 GMT (5:26 p.m. EDT)

T+plus 4 minutes. Negative return. The shuttle is traveling too fast and is too far downrange so it can no longer return to the launch site in the event of a main engine problem.

2125 GMT (5:25 p.m. EDT)

T+plus 3 minutes. Altitude 45 miles, downrange distance 71 miles. The Orbital Maneuvering Engines have now ignited to assist the boost to orbit.

2125 GMT (5:25 p.m. EDT)

T+plus 2 minutes, 30 seconds. Altitude 34 miles, downrange distance 41 miles.

2124 GMT (5:24 p.m. EDT)

T+plus 2 minutes, 10 seconds. The twin solid rocket boosters have done their job and separated from the space shuttle Endeavour. The shuttle continues its climb to orbit on the power of the three liquid-fueled main engines.

2124 GMT (5:24 p.m. EDT)

T+plus 90 seconds. All systems of Endeavour are performing well as the shuttle accelerates to orbit. Burning propellant at remarkable rates, the shuttle weighs half of what it did at liftoff.

2123 GMT (5:23 p.m. EDT)

T+plus 60 seconds. Endeavour's engines have throttled back up.

2123 GMT (5:23 p.m. EDT)

T+plus 35 seconds. Endeavour's three main engines are being throttled down to lessen the aerodynamic stesses on the vehicle as it powers through the dense lower atmosphere.

2123 GMT (5:23 p.m. EDT)

T+plus 20 seconds. The shuttle has rolled to the proper heading for its northeasterly trajectory up the Eastern Seaboard on the two-day chase to catch the orbiting International Space Station. The outpost is currently cruising 240 miles above the southern Indian Ocean, west of Perth, Australia.

2122:49 GMT (5:22:49 p.m. EDT)

LIFTOFF! Liftoff of shuttle Endeavour -- launching a new station crew to continue our international foothold in space. And the tower is clear!

2122:18 GMT (5:22:18 p.m. EDT)

T-minus 31 seconds. Auto sequence start. Endeavour's onboard computers have assumed control of the countdown.

In the next few seconds the solid rocket booster hydraulic power units will be started and the orbiter's body flap and speed brake will be moved to their launch positions. The main engine ignition will begin at T-minus 6.6 seconds.

2121:49 GMT (5:21:49 p.m. EDT)

T-minus 1 minute. Computers verifying that the main engines are ready for ignition. Sound suppression water system is armed. System will activate at T-minus 16 seconds to suppress the sound produced at launch. Residual hydrogen burn ignitors have been armed. They will be fired at T-minus 10 seconds to burn off any hydrogen gas from beneath the main engine nozzles. And the solid rocket booster joint heaters have been deactivated.

Shortly the external tank strut heaters will be turned off; Endeavour will transition to internal power; the liquid oxygen and liquid hydrogen outboard fill and drain valves will be closed; the payload bay vent doors will be positioned for the launch; and the gaseous oxygen vent arm will be verified fully retracted.

2120 GMT (5:20 p.m. EDT)

T-minus 2 minutes, 30 seconds. Orbiter steering check now complete -- the main engine nozzles in their start positions. The external tank liquid oxygen vent valve has been closed and pressurization of the LOX tank has started. Standing by to transfer Endeavour's power-producing fuel cells to internal reactants. The units will begin providing all electricity for the mission beginning at T-50 seconds. And pilot Paul Lockhart has been asked to clear the caution and warning memory system aboard Endeavour.

In the next few seconds the gaseous oxygen vent hood will be removed from the top of the external tank. Verification that the swing arm is fully retracted will be made by the ground launch sequencer at the T-37 second mark.

Coming up on T-minus 2 minutes. The astronauts will be instructed to close and lock the visors on their launch and entry helmets. At T-minus 1 minute, 57 seconds the replenishment of the flight load of liquid hydrogen in the external tank will be terminated and tank pressurization will begin.

2119 GMT (5:19 p.m. EDT)

T-minus 3 minutes, 30 seconds. The main engine nozzles now being moved through a computer controlled test pattern to demonstrate their readiness to support guidance control during launch today.

2118 GMT (5:18 p.m. EDT)

T-minus 4 minutes. Activation of the APUs complete. The three units are up and running. The final helium purge sequence is under way in the main propulsion system. This procedure readies fuel system valves for engine start. In the next few seconds the aerosurfaces of Endeavour will be run through a pre-planned mobility test to ensure readiness for launch. This is also a dress rehearsal for flight of the orbiter's hydraulic systems.

2117 GMT (5:17 p.m. EDT)

T-minus 5 minutes. Go for Auxiliary Power Unit start. Pilot Paul Lockhart is now flipping three switches in Endeavour's cockpit to start each of the three APU's. The units, located in the aft compartment of Endeavour, provide the pressure needed to power the hydraulic systems of the shuttle. The units will be used during the launch and landing phases of the mission for such events are moving the orbiter's aerosurfaces, gimbaling the main engine nozzles and deploying the landing gear.

Over the course of the next minute, the orbiter's heaters will be configured for launch by commander Ken Cockrell, the fuel valve heaters on the main engines will be turned off in preparation for engine ignition at T-6.6 seconds and the external tank and solid rocket booster safe and arm devices will be armed.

2117 GMT (5:17 p.m. EDT)

T-minus 5 minutes, 30 seconds. APU pre-start is complete and the units are ready for activation. The orbiters flight data recorders now in the record mode to collect measurements of shuttle systems performance during flight.

2116 GMT (5:16 p.m. EDT)

T-minus 6 minutes. Pilot Paul Lockhart has been asked by Orbiter Test Conductor George Gross to pre-start the orbiter Auxiliary Power Units. This procedure readies the three APU's for their activation after the countdown passes T-minus 5 minutes.

2115 GMT (5:15 p.m. EDT)

T-minus 7 minutes, 30 seconds. The ground launch sequencer is now pulling the orbiter access arm away from the crew hatch on the port side of the vehicle. The arm was the passage way for the astronauts to board Endeavour a few hours ago. The arm can be re-extended in about a quarter of a minute should the need arise later in the countdown.

2114 GMT (5:14 p.m. EDT)

T-minus 8 minutes and counting. Pilot Paul Lockhart has flipped the switches in the cockpit of Endeavour to directly connect the three onboard fuel cells with the essential power buses. Also, the stored program commands have been issued to the orbiter for the final antenna alignment and management for today's launch.

2113:49 GMT (5:13:49 p.m. EDT)

T-minus 9 minutes and counting. The ground launch sequencer is now controlling the final phase of today's countdown to launch of space shuttle Endeavour at 5:22:49 p.m. EDT. The GLS will monitor as many as a thousand different measurements to ensure they do not fall out of predetermine red-line limits.

The launch of STS-111 will mark the 110th flight in the space shuttle program since 1981, the 85th since return-to-flight after Challenger, the 18th for Endeavour and the third shuttle flight of 2002.

2112:49 GMT (5:12:49 p.m. EDT)

One minute remaining in this built-in hold.

Once the countdown picks up, the Ground Launch Sequencer will be initiated. The master computer program is located in a console in Firing Room 1 of the Complex 39 Launch Control Center. The GLS is the master of events through liftoff. During the last 9 minutes of the countdown, the computer will monitor as many as a thousand different systems and measurements to ensure that they do not fall out of any pre-determine red-line limits. At T-minus 31 seconds, the GLS will hand off to the onboard computers of Endeavour to complete their own automatic sequence of events through the final half minute of the countdown.

2110 GMT (5:10 p.m. EDT)

NASA Launch Director Mike Leinbach has polled senior officials and no technical problems were announced. The launch weather conditions were also verified "go" for liftoff with no constraints.

2109 GMT (5:09 p.m. EDT)

The final readiness poll by NASA Test Director Steve Altemus has been completed with all launch team members reporting "go", including the orbiter, external tank, solid rocket boosters, safety personnel, Eastern Range and the astronaut crew. Mission Control also has given its "go" which indictates weather at Kennedy Space Center's Shuttle Landing Facility and other abort landing sites are acceptable for launch today.

2108 GMT (5:08 p.m. EDT)

Five minutes remaining in the hold. Coming up on the final pre-launch management polls. 2059 GMT (4:59 p.m. EDT)

All the launch weather rules remain "go" for launch.

2053 GMT (4:53 p.m. EDT)

Now 30 minutes away from launch time. Weather remains optimistic at this point.

Two solid rocket booster recovery ships -- the Freedom Star and Liberty Star -- are reported on station in the Atlantic Ocean about 140 miles northeast of Kennedy Space Center, off the coast of Jacksonville, Florida. They were deployed from Port Canaveral to support the launch.

The ships will retrieve and return the spent boosters to the Cape for disassembly and shipment back to Utah for refurbishment and reuse on a future shuttle launch.

Following the boosters' parachuted descent and splashdown in the Atlantic, the recovery teams will configure the SRBs for tow back to Port Canaveral later this week.

2046 GMT (4:46 p.m. EDT)

The KSC restricted area has been verified clear for launch.

2038 GMT (4:38 p.m. EDT)

Mission Control has tweaked the close of today's window to 5:27:23 p.m. EDT.

2028 GMT (4:28 p.m. EDT)

T-minus 9 minutes and holding. Countdown clocks have gone into this final planned hold before today's launch. The hold will last 45 minutes and 49 seconds leading to liftoff at 5:22:49 p.m. EDT. The available launch window extends to 5:27:28 p.m. EDT.

2025 GMT (4:25 p.m. EDT)

The fuel cell loads are being adjusted. And the gaseous nitrogen purge to the aft skirts of the solid rocket boosters is starting.

2023 GMT (4:23 p.m. EDT)

The Main Propulsion System helium system is being reconfigured. And the OMS crossfeed valves are being configured for launch.

2021 GMT (4:21 p.m. EDT)

At this point in the countdown, pilot Lockhart is configuring the displays inside Endeavour's cockpit for launch while commander Cockrell enables the abort steering instrumentation. And Mission Control in Houston is loading Endeavour's onboard computers with the proper guidance parameters based on the projected launch time.

2017 GMT (4:17 p.m. EDT)

T-minus 20 minutes and counting. The countdown has resumed. Clocks will tick down for the next 11 minutes to T-minus 9 minutes where the final planned hold is scheduled to occur. The hold length will be adjust to synch up with today's preferred launch time of 5:22:49 p.m. EDT. The available launch window will extend for four minutes and 39 seconds to 5:27:28 p.m. EDT.

Weather remains "go" and there are no significant hardware problems being addressed.

Endeavour's onboard computers are now transitioning to the Major Mode-101 program, the primary ascent software. Also, engineers are dumping the Primary Avionics Software System (PASS) onboard computers. The data that is dumped from each of PASS computers is compared to verify that the proper software is loaded aboard for launch.

In about one minute, the astronauts will configure the backup computer to MM-101 and the test team will verify backup flight control system (BFS) computer is tracking the PASS computer systems.

2011 GMT (4:11 p.m. EDT)

The Orbiter Closeout Crew has completed it's work and is now leaving the launch pad.

2007 GMT (4:07 p.m. EDT)

T-minus 20 minutes and holding. The countdown has paused for a 10-minute built-in hold. Launch remains scheduled for 5:22:49 p.m. EDT. Weather forecasters are remaining generally optimistic and there are no technical problems being worked.

During this built-in hold, all computer programs in the Firing Room of the Complex 39 Launch Control Center will be verified to ensure that the proper programs are available for the countdown; the landing convoy status will be verified and the landing sites will be checked to support an abort landing during launch today; the Inertial Measurement Unit preflight alignment will be verified completed; and preparations are made to transition the orbiter onboard computers to Major Mode 101 upon coming out of the hold. This configures the computer memory to a terminal countdown configuration.

1958 GMT (3:58 p.m. EDT)

Commander Ken Cockrell is pressurizing the gaseous nitrogen system for Endeavour's Orbital Maneuvering System engines, and pilot Paul Lockhart is activating the gaseous nitrogen supply for the orbiter's Auxiliary Power Units' water spray boilers.

1956 GMT (3:56 p.m. EDT)

Mission Control has just announced that today's target liftoff time has been tweaked to 5:22:49 p.m. EDT -- a one-second change based upon the latest radar tracking of the International Space Station's orbit. The station will be above the southern Indian Ocan west of Perth, Australia at launch as Endeavour begins a two-day chase to catch the orbiting soutpost.

In the countdown the shuttle's backup flight control system (BFS) computer is being configured for launch. It would be used today in the event of emergency landing.

Also, the primary avionics software system (PASS) is transferring to Endeavour's BFS computer so both systems can be synched with the same data. In case of a PASS computer system failure, the BFS computer will take over control of the shuttle vehicle during flight.

The ground pyro initiator controllers (PICs) are scheduled to be powered up at this time in the countdown. They are used to fire the solid rocket hold-down posts, liquid oxygen and liquid hydrogen tail service mast and external tank vent arm system pyros at liftoff and the space shuttle main engine hydrogen gas burn system prior to engine ignition.

Endeavour's two Master Events Controllers also are being tested. They relay the commands from the shuttle's computers to ignite, and then separate the boosters and external tank during launch.

1946 GMT (3:46 p.m. EDT)

The Ground Launch Sequencer mainline activation has been completed. The master computer system is now processing data. The GLS will monitor key systems over the rest of the launch attempt and control the final nine minutes of the countdown.

1942 GMT (3:42 p.m. EDT)

At this point in the countdown, the Air Force Eastern Range shuttle safety system terminal count closed-loop test will be performed to verify the countdown can be stopped in the final seconds before liftoff should a safety issue arise.

1930 GMT (3:30 p.m. EDT)

The hatch is now confirmed to be closed and latched for flight.

1927 GMT (3:27 p.m. EDT)

T-minus 1 hour and counting. The pre-flight alignment of Endeavour's Inertial Measurement Units is now beginning, and will be completed by the T-minus 20 minute hold. The IMUs were calibrated over the past few hours of the countdown. The three units are used by the onboard navigation systems to determine the position of the orbiter in flight.

Meanwhile, the S-band antennas at the MILA tracking station here at the Cape are shifting from low power to high power. The site will provide voice, data and telemetry relay between Endeavour and Mission Control during the first few minutes of flight. Coverage then is handed to a NASA Tracking and Data Relay Satellite in space.

1920 GMT (3:20 p.m. EDT)

Endeavour's crew module hatch has swung shut and Orbiter Closeout Crew is working to latch it. Pressure and leak checks will be performed shortly to ensure a good seal on the hatch for today's launch, which is now just under two hours away at 5:23 p.m. EDT.

1910 GMT (3:10 p.m. EDT)

The Orbiter Closeout Crew has been given a "go" to exit Endeavour's crew module and close the hatch for flight.

1900 GMT (3:00 p.m. EDT)

In a somewhat unusual move, the Cape weather team has changed the odds of meeting the launch weather rules today. The forecast had called for a 60 percent chance of not launching due to thick clouds and triggered lightning concerns. But meteorologists have just improved the precentage to only a 20 percent chance of weather prohibiting launch. Clouds and crosswinds are the two issues that will be watched as the day continues.

At this point in the count, the ground launch sequencer software that will control the final nine minutes of the countdown will be initialized.

Also, the solid rocket boosters' gas generator heaters in the hydraulic power units are turned on, the aft skirt gaseous nitrogen purge is starting and the rate gyro assemblies (RGAs) are being activated. The RGAs are used by the orbiter's navigation system to determine rates of motion of the boosters during the first-stage flight.

1839 GMT (2:39 p.m. EDT)

Mission specialist Franklin Chang-Diaz, set for the record-matching seventh space flight, has now boarded Endeavour. All seven astronauts are now inside the shuttle for launch.

1831 GMT (2:31 p.m. EDT)

The commander of Expedition 5 -- the fifth resident crew to live aboard the International Space Station -- Russian cosmonaut Valeri Korzun is now inside Endeavour.

1826 GMT (2:26 p.m. EDT)

Endeavour mission specialist Philippe Perrin of the French space agency has now made his way into the shuttle.

1823 GMT (2:23 p.m. EDT)

Now three hours away from launch time. Although all weather rules at Kennedy Space Center are currently "go" for liftoff, the Air Force weather spokesperson says it isn't a done deal yet that the weather will cooperate. The concern going into this launch attempt was thick, high clouds. Those clouds have thinned out more than expect, which is a good thing. But since the clouds are thinning and breaking up, the sun is now able to heat up the surface more than expected and that could trigger thunderstorms.

1815 GMT (2:15 p.m. EDT)

Expedition 5 astronaut Peggy Whitson is now climbed into the hatch.

1814 GMT (2:14 p.m. EDT)

Pilot Paul Lockhart is now aboard the shuttle Endeavour.

1802 GMT (2:02 p.m. EDT)

Expedition 5 crew member Sergei Treschev has also climbed into the shuttle.

1800 GMT (2:00 p.m. EDT)

NASA has lifted the remaining secrecy surrounding the countdown by announcing the Endeavour astronauts have arrived at launch pad 39A.

The crew took the elevator to the 195-foot level of the pad structure where the Orbiter Access Arm is located with the White Room. In the White Room the crew will be outfitted with the rest of their gear and communications hat before entering Endeavour's crew module hatch.

Commander Ken Cockrell is already onboard the shuttle.

All weather rules are currently "go" for launch and meteorologists are becoming more optimistic this afternoon that the clouds will be thin enough to permit an on-time launch at 5:23 p.m. EDT.

1743 GMT (1:43 p.m. EDT)

With a chopper and NASA security escort, the crew aboard the AstroVan has just driven past the press site on their way to launch pad 39A. The convoy stopped briefly in front of the Launch Control Center for managers to get out of the AstroVan and make their way into the Firing Room. Also, Chief Astronaut Charlie Precourt jumped out and will head to the Shuttle Landing Facility to begin weather reconnaissance flights in a T-38 jet and later in the Shuttle Training Aircraft.

1727 GMT (1:27 p.m. EDT)

T-minus 3 hours and counting. The countdown has resumed on scheduled from this planned two-hour built-in hold. Clocks will now tick down to T-minus 20 minutes when the next hold is planned. A final hold is scheduled at the T-minus 9 minute mark. Liftoff remains set for 5:23 p.m. EDT.

1650 GMT (12:50 p.m. EDT)

The crew of space shuttle Endeavour will soon receive a routine pre-flight weather briefing with flight controllers in Houston before finishing their suit up chores and departing for the launch pad. A disturbance in the Gulf of Mexico continues to spew clouds over most of Florida. Meteorologists say there is a 60 percent chance the cloud conditions will prohibit liftoff today.

1625 GMT (12:25 p.m. EDT)

Following tanking procedures, a team called the Final Inspection Team was dispatched to the pad to check the vehicle one last time prior to liftoff. The six-person team, comprised of five engineers and one safety official, is currently performing the inspections at pad 39A. At the conclusion of their two-hour tour-of-duty, they will have walked up and down the entire fixed service structure and mobile launcher platform.

The team is on the lookout for any abnormal ice or frost build-up on the vehicle that could break-off during ignition and damage the spacecraft. The team is also searching for any loose debris that could possibly fly up and strike the vehicle at launch. And the third item of interest to the team is the thermal integrity of the external tank foam insulation.

The team uses a portable infrared scanner that gathers temperature measurements on the surface area of the shuttle and can spot leaks. The scanner will be used to obtain temperature data on the external tank, solid rocket boosters, space shuttle orbiter, main engines and launch pad structures. The scanner can also spot leaks of the cryogenic propellants, and due to its ability to detect distinct temperature differences, can spot any dangerous hydrogen fuel that is burning. One team member is also responsible for photo documentation.

Each member of the Final Inspection Team is in constant contact with NASA Test Director Steve Altemus in the Firing Room.

The team wears the highly visible day-glow orange coveralls that are anti-static and flame resistant. Each member also has a self-contained emergency breathing unit that holds about 10 minutes of air.

Following the Final Inspection Team's activities, they will meet with NASA Launch Director Mike Leinbach, the Mission Management Team, and engineering directors in the launch control center, providing a detailed report on the inspections and findings at the pad 39A.

A full inspection of the vehicle and pad was performed yesterday and the external tank received a thorough check prior to fueling today.

An inspection of the launch pad and beach will be made following launch. That inspection will be to look for anything unusual, particularly anything that could have fallen off of the vehicle during the first few seconds of flight. Later, there will be a meeting to review high-speed videotape and film of the launch and early ascent to determine if there was any damage to the vehicle.

1550 GMT (11:50 a.m. EDT)

The countdown clocks are currently hold at the T-minus 3 hour mark. The planned two-hour hold will last until 1:27 p.m. EDT.

From Bill Harwood/CBS News:
The primary goal of the mission is to deliver a fresh crew to the international space station and to bring the lab's current occupants home after 194 days in space - a U.S. endurance record.

"We're looking forward to having this over with. It's not a very nice feeling," someone said earlier today in air-to-ground traffic between Russian flight controllers and the station. Expedition 4 commander Yuri Onufrienko asked about the forecast and said the weather was just fine in orbit.

Onufrienko and his two American crewmates, Daniel Bursch and Carl Walz, were launched to the station Dec. 5. Had Endeavour taken off on time last Thursday, their mission would have ended just a few hours shy of the U.S. space endurance mark of 188.4 days set by Shannon Lucid aboard the Russian Mir space station in 1996.

Assumuming Endeavour gets off the pad today, Walz and Bursch will log 193 days 17 hours and 30 minutes off the planet, beating Lucid's mark by nearly a week.

Today's launching marks the second time Endeavour has been fueled for a launch attempt. But three other launch dates - last Friday, Monday and Tuesday - were scrubbed before fueling ever began because of expected bad weather and work to replace a nitrogen regulator in the shuttle's left-side orbital maneuvering system rocket pod.

1536 GMT (11:36 a.m. EDT)

Endeavour's external fuel tank is now full with 528,000 gallons of super-cold liquid oxygen and liquid hydrogen. Hydrogen loading was finished at 11:18 a.m., followed by oxygen at 11:32 a.m. EDT.

But given the cryogenic nature of the oxidizer and propellant, the supplies naturally boil away. So the tanks are continuously topped off until the final minutes of the countdown in a procedure called "stable replenishment."

With the hazardous tanking operation completed, the Orbiter Closeout Crew and Final Inspection Team are being dispatched to the pad to perform their jobs. The closeout crew will ready Endeavour's crew module for the astronauts' boarding in a couple of hours; and the inspection team will give the entire vehicle a check for any ice formation from fueling.

There are no technical problems being reported at this hour. Weather is still iffy, but will be watched as the day goes on. Liftoff is still targeted for 5:22:48 p.m. EDT.

1250 GMT (8:50 a.m. EDT)

The loading of 528,000 gallons of super-cold liquid hydrogen and liquid oxygen into space shuttle Endeavour's external tank to power the ship's three main engines during launch has finally begun. The three-hour operation officially started at 8:41 a.m. EDT.

A false fire alarm forced workers to return to the launch pad, delaying fueling about 40 minutes.

There are actually two tanks inside the shuttle's orange bullet-shaped tank. The liquid oxygen tank fills the top third of the external tank. It will be filled with 143,000 gallons of liquid oxygen chilled to minus 298 degrees Fahrenheit (minus 183 degrees Celsius). The liquid hydrogen tank is contained in the bottom two-thirds of the external tank. It holds 385,000 gallons of liquid hydrogen chilled to minus 423 degrees Fahrenheit (minus 253 degrees Celsius).

The cryogenics are pumped from storage spheres at the pad, through feed lines that pass through the mobile launcher platform, into Endeavour's aft compartment and finally into the external fuel tank.

The fueling process is being orchestrated by engineers in the safe confines of the Kennedy Space Center's Launch Control Center located about three-and-a-half miles from Endeavour at launch pad 39A.

Launch of Endeavour remains scheduled for 5:22:48 p.m. EDT today. Weather remains a problem, with forecaster predicting a 60 percent chance of a delay due to high clouds.

1200 GMT (8:00 a.m. EDT)

The start of fueling will delayed until at least 8:30 a.m. this morning because a team of workers has been dispatched to the launch pad to investigate an alarm that was detected. The hazardous operation to load the shuttle with fuel cannot occur while there are people on the pad.

1145 GMT (7:45 a.m. EDT)

The Mission Management Team is meeting at this time for their standard review of the progress made during the countdown, any outstanding technical issues and the weather forecast before giving engineers approval to begin fueling Endeavour this morning.

TUESDAY, JUNE 4, 2002
2115 GMT (5:15 p.m. EDT)

Here is a look at some of the key countdown milestones leading to launch of Endeavour at 5:22:48 p.m. EDT (2122:48 GMT) Wednesday.

The countdown is current in a scheduled built-in hold at the T-11 hour mark. activities planned tonight:

• Flight crew equipment late stow
• Move Rotating Service Structure to the park position
• Perform ascent switch list
• Fuel cell flow-through purge complete

• Resume countdown at T-11 hours (2:27 a.m.)
• Activate the orbiter's fuel cells (3:37 a.m.)
• Clear the blast danger area of all non-essential personnel
• Switch Endeavour's purge air to gaseous nitrogen (4:42 a.m.)
• Enter planned two-hour built-in hold at the T-6 hour mark (7:27 a.m.)
• Launch team verifies no violations of launch commit criteria prior to cryogenic loading of the external tank
• Clear pad of all personnel
• Begin three-hour loading the external tank with about 500,000 gallons of cryogenic propellants (about 7:57 a.m.)
• Resume countdown at T-6 hours (8:27 a.m.)
• Enter planned two-hour built-in hold at T-3 hours (11:27 a.m.)

Watch this page for complete live coverage throughout the day on Wednesday beginning with the start of fueling.

2100 GMT (5:00 p.m. EDT)

Launch of space shuttle Endeavour is scheduled for 5:22:48 p.m. EDT tomorrow, NASA just announced. The available launch window extends from 5:17:49 p.m. to 5:27:47 p.m. EDT.

The space agency does not reveal the precise launch timing until about 24 hours in advance as part of its new post-September 11 security measures.

1500 GMT (11:00 a.m. EDT)

Engineers have completed the replacement of a nitrogen regulator in the shuttle Endeavour's left-side rocket pod and topped off the ship's on-board supplies of liquid oxygen and hydrogen, clearing the way for another launch attempt Wednesday afternoon. The weather remains a major question mark, however. Read full story.

MONDAY, JUNE 3, 2002
1600 GMT (12:00 p.m. EDT)

Technicians have removed the faulty gaseous nitrogen regulator on Endeavour's left OMS engine and installed a new one. Testing of the replacement unit is underway today.

Officials expect that work to be completed by later tonight so the shuttle's three power-generating fuel cells can be serviced for another round of launch attempts starting Wednesday.

The weather forecast for Wednesday now calls for a 60 percent chance of acceptable conditions. The main threat comes in the form of anvil clouds from thunderstorms. Here is Launch Weather Officer Kathy Winters' forecast issued this morning:

"Weather conditions are improving at KSC. With a high-pressure ridge building into North Florida on Wednesday, winds associated with the pressure gradient will shift to the southeast near the surface and east through the mid-levels. With this type of flow, the sea breeze that begins late in the morning will push well inland. With plenty of moisture still evident in the atmosphere, thunderstorms will again be generated by low-level convergence associated with the sea breeze, but storms will continue to move west, away from KSC, after forming. Still, winds at 35,000 to 45,000 feet will be from the west resulting in a threat from anvil clouds generated by these inland thunderstorms."

Winters says there is a 60 percent chance of launching on Thursday and 40 percent on Friday.

The seven astronauts to ride Endeavour into orbit -- the four orbiter crew members and the three-person Expedition 5 space station crew -- have remained at Kennedy Space Center throughout this extended delay.

SUNDAY, JUNE 2, 2002

NASA managers today delayed the shuttle Endeavour's launch yet another day, from Tuesday to Wednesday, because of time need to bring in equipment to test a replacement nitrogen valve in the ship's left-side orbital maneuvering system rocket pod. Read full story.

1552 GMT (11:52 a.m. EDT)

Replacement of the troublesome gaseous nitrogen regulator on Endeavour's left OMS engine began this morning. But due to delays getting test equipment to the launch site, NASA has been forced to slip Endeavour's target launch date from Tuesday to Wednesday.

Wednesday's preliminary weather forecast calls for a 50 percent chance of acceptable conditions. The forecast is expected to worsen later in the week.

1500 GMT (11:00 a.m. EDT)

Launch of Endeavour is being bumped back yet another day. NASA is rescheduling the shuttle's liftoff to Wednesday after technicians apparently ran into some sort of difficulty getting the equipment needed to test the new gaseous nitrogen regulator, sources said.

SATURDAY, JUNE 1, 2002

Technicians are replacing the faulty gaseous nitrogen regulator on space shuttle Endeavour today. The work to remove the old one and install a new unit is expected to take until Sunday afternoon.

NASA officials have decided to target Tuesday as the new launch date for Endeavour. The weather forecast remains iffy given the continued prediction of daily thunderstorms across Florida.

1512 GMT (11:12 a.m. EDT)

Shuttle managers are meeting at this hour to discuss a problem with the gaseous nitrogen valve on Endeavour's left Orbital Maneuvering System engine. That regulator experienced a problem during Thursday's countdown. Although engineers believed it was just a momentary glitch and cleared Endeavour for launch before weather ultimately scrubbed the attempt, controllers have since detected leakage from the valve.

Officials are now planning to have the unit replaced before Endeavour can fly, a job that will further delay launch. Sources say a Monday launch attempt is no longer possible, but it is unclear at this point if the work can be completed in time for a Tuesday or Wednesday launch try.

The valve in question provides the pressurized nitrogen used to operate the propellant valves that feed fuel to the OMS-pod engines. The OMS engines are used to circularize a shuttle's orbit after launch, to make major altitude changes and to slow the ship for re-entry.

FRIDAY, MAY 31, 2002
1900 GMT (03:00 p.m. EDT)

With heavy rain pounding the Kennedy Space Center and no let up in sight, NASA managers moved up a planned 7:30 p.m. shuttle launch review meeting to 2 p.m. and promptly ruled out any attempt to launch the shuttle Endeavour on Saturday. Read full story.

1410 GMT (10:10 a.m. EDT)

With a dismal weather forecast and possibility of hail during thunderstorms later today, shuttle managers decided not to attempt launching space shuttle Endeavour on its mission to the International Space Station this evening.

The massive Rotating Service Structure will be rolled back into place around Endeavour today to shield the orbiter from the weather.

Meteorologists say there is again a 70 percent chance of unfavorable weather on Saturday evening. But officials will meet at 7:30 p.m. EDT tonight to determine if launch will be reset to Saturday.

It is believed that if Endeavour does not launch by Saturday evening, then launch would have to be delayed a couple days to allow technicians to replenish the shuttle's power-generating fuel cell reactants.

If NASA decides at the meeting tonight to stand down and allow the fuel cell servicing to occur over the weekend, launch could be rescheduled for Monday. But if another countdown is made on Saturday and Endeavour still does not get off the ground, the servicing work would likely push the next launch attempt to Tuesday.

1357 GMT (9:57 a.m. EDT)

SCRUB! NASA has just announced that today's try to launch space shuttle Endeavour has been cancelled. Officials plan to meet at 7:30 p.m. EDT tonight to decide whether to reschedule for a Saturday evening liftoff. More details as we get them.

1330 GMT (9:30 a.m. EDT)

The Mission Management Team has convened its meeting this morning to decide whether to proceed with re-fueling Endeavour's external tank for another launch attempt today. If approved, fueling should begin in about 40 minutes or so.

0320 GMT (11:20 p.m. EDT Thurs.)

The weather forecast for Friday evening's launch attempt is calling for a 70 percent chance of unacceptable conditions due to thunderstorms around Kennedy Space Center.

"KSC will again have a sea breeze by late morning generating an easterly flow. With plenty of moisture available in the atmosphere, the low-level convergence caused by the interaction of the Florida sea breezes will generate thunderstorms in the center portion of the state. These storms will move towards the east after development causing concerns for launch. Additionally, upper level wind flow will be stronger Friday increasing the threat from anvil clouds from the thunderstorms that form inland," Launch Weather Officer Kathy Winters reported in her forecast Thursday evening after the scrub.

The forecast for Saturday and Sunday also calls for 70 percent "no go" weather because of thunderstorms.

0230 GMT (10:30 p.m. EDT Thurs.)

Launch director Michael Leinbach called off Thursday's attempt to launch the shuttle Endeavour on a space station crew rotation mission because of thunderstorms and electrical activity encroaching from the west. Read full story on the scrub and NASA's plans for further launch attempts if the weather remains unfavorable.

0050 GMT (8:50 p.m. EDT Thurs.)

Endeavour's seven crew members have left the orbiter and are on the way back to their quarters at the Operations and Checkout Building. NASA will make another launch attempt on Friday at 7:22 p.m. EDT (2322 GMT).

0017 GMT (8:17 p.m. EDT Thurs.)

Endeavour's crew module hatch has just been opened.

Meteorologists report that the next four days have about the same weather forecast. So since there isn't one day that looks more favorable than another, officials have decided to try again at 7:22 p.m. EDT Friday.

0005 GMT (8:05 p.m. EDT Thurs.)

The Mission Management Team has decided to make another launch attempt on Friday evening. The launch window extends from 7:17 to 7:27 p.m. EDT, with the preferred liftoff time of 7:22 p.m. EDT.

However, thunderstorms are again in the forecast. Meteorologists say there is a 70 percent chance weather will scrub the launch.

If launch does not occur Friday evening, then officials will assess when the next try would be made. The shuttle's electricity-producing fuel cells have to be topped off this weekend to ensure the ship has enough liquid oxygen and liquid hydrogen reactants for the full 12-day mission. The cryogenics naturally boil away on the launch pad, which force engineers to replenish the tanks after a few launch attempts.

THURSDAY, MAY 30, 2002
2338 GMT (7:38 p.m. EDT)

The Orbiter Closeout Crew has been dispatched back to pad 39A to open Endeavour's hatch and help the seven astronauts out of the shuttle.

Although NASA is protecting the option for another launch attempt Friday, officials are meeting to determine if they want to skip tomorrow and try again this weekend based on the unfavorable weather forecast for tomorrow. A decision could be made within the next 45 minutes or so.

2323 GMT (7:23 p.m. EDT)

Officials called off this evening's launch attempt because there was simply no hope the weather would improve by the 7:44 p.m. EDT liftoff time. The anvil cloud rule remains "no go" for launch at the pad and at the shuttle runway here at Kennedy Space Center.

NASA will now prepare for another launch try Friday. The launch window will extend from 7:17 to 7:27 p.m. EDT, with the target liftoff time of 7:22 p.m. EDT.

2321 GMT (7:21 p.m. EDT)

SCRUB! The launch team has just been informed that today's countdown has been scrubbed due to the weather. Safing is now in progress.

2320 GMT (7:20 p.m. EDT)

Engineers have reviewed the OMS pressure regulator and say some contamination appears to have caused the initial problem. That has been flushed out and the troubleshooting has revealed the system is now ready for flight.

2318 GMT (7:18 p.m. EDT)

The thick cloud rule for launch weather is now "go" but anvil clouds remain "no go".

2316 GMT (7:16 p.m. EDT)

In addition to launch weather being "no go", Mission Control is responsible for forecasting conditions at the shuttle runway here at Kennedy Space Center that Endeavour would use about 35 minutes after liftoff in the event of a major problem. Houston meteorologists say conditions at the runway are "no go" at the moment and forecast "no go".

2312 GMT (7:12 p.m. EDT)

T-minus 9 minutes and holding. Countdown clocks have gone into this final planned hold before today's launch. The hold will last 23 minutes leading to liftoff at 7:44:26 p.m. EDT. The available launch window extends to 7:49:25 p.m. EDT.

However, weather remains "no go" due to anvil clouds and thick clouds. The technical issue with the OMS pressure regulator has not been officially resolved yet either.

2310 GMT (7:10 p.m. EDT)

Mission Control in Houston is loading Endeavour's onboard computers with the proper guidance parameters based on the projected launch time.

2309 GMT (7:09 p.m. EDT)

The fuel cell loads are being adjusted and the OMS crossfeed valves are being configured for launch.

2307 GMT (7:07 p.m. EDT)

The Main Propulsion System helium system is being reconfigured. And the gaseous nitrogen purge to the aft skirts of the solid rocket boosters is starting.

2305 GMT (7:05 p.m. EDT)

The latest check on the launch weather rules shows the thick cloud and anvil cloud rules are being violated at this time.

At this point in the countdown, pilot Lockhart is configuring the displays inside Endeavour's cockpit for launch while commander Cockrell enables the abort steering instrumentation.

2303 GMT (7:03 p.m. EDT)

Although the regulator appears to be working now, officials still need to verify the rationale to fly today and ensure there are no lingering concerns with the system.

2301 GMT (7:01 p.m. EDT)

T-minus 20 minutes and counting. The countdown has resumed. Clocks will tick down for the next 11 minutes to T-minus 9 minutes where the final planned hold is scheduled to occur. The hold length will be adjust to synch up with today's preferred launch time of 7:44:26 p.m. EDT. Today's launch window extends from about 7:39 p.m. to 7:49 p.m. EDT.

Endeavour's onboard computers are now transitioning to the Major Mode-101 program, the primary ascent software. Also, engineers are dumping the Primary Avionics Software System (PASS) onboard computers. The data that is dumped from each of PASS computers is compared to verify that the proper software is loaded aboard for launch.

In about one minute, the astronauts will configure the backup computer to MM-101 and the test team will verify backup flight control system (BFS) computer is tracking the PASS computer systems.

2300 GMT (7:00 p.m. EDT)

The launch team engineer reports the troubleshooting test found that the pressure held stable and recommends continuing with the countdown. The regulator is used to provide the nitrogen used to operate the valves that feed propellant to the OMS engines.

2258 GMT (6:58 p.m. EDT)

A troubleshooting test of the Orbital Maneuvering System is now underway. NASA says this will simulate an on-orbiting engine firing.

2256 GMT (6:56 p.m. EDT)

Troubleshooting continues. There has been no further update from NASA on the status of the problem. It is unclear at this point if the problem can be resolved in the time left before launch. Liftoff is scheduled for 7:44:26 p.m. EDT with a five-minute window extending to 7:49:25 p.m.

2252 GMT (6:52 p.m. EDT)

The Orbiter Closeout Crew has completed its work to secure the White Room and is now leaving the launch pad.

There is no estimation on how much longer this extended hold at the T-minus 20 minute mark will last.

2248 GMT (6:48 p.m. EDT)

The built-in hold has been extended further. If the countdown is restarted, the 45-minute hold at T-9 minutes would be reduced to synch up with the 7:44 p.m. EDT launch time. However, the regulator problem continues to be worked. Engineers believe that a valve in the regulator may be to blame for this overpressure situation.

2243 GMT (6:43 p.m. EDT)

The launch weather rule for no anvil clouds around the launch site is now "no go" for launch.

2240 GMT (6:40 p.m. EDT)

Hold extended! Officials have decided to extend this hold at the T-minus 20 minute mark for another 10 minutes to give the launch team more time to troubleshoot the regulator problem. During pressurization of the gaseous nitrogen system for Endeavour's Orbital Maneuvering System engines, an overpressure was seen. The system was then safed. NASA spokesman Bruce Buckingham says this could indicate a failure of the pressure regulator in the system.

2231 GMT (6:31 p.m. EDT)

NASA says the Orbital Maneuvering System pressure regulator that is being called into question is on the left engine. Endeavour has two OMS engines on its tail. Engineers are trying to determine if the regulator has failed or if there is some other problem.

This is the first significant technical problem worked in this afternoon's countdown.

2229 GMT (6:29 p.m. EDT)

T-minus 20 minutes and holding. The countdown has paused for a 10-minute built-in hold. Launch remains scheduled for 7:44 p.m. EDT. The launch team is looking at a pressure regulator on one of Endeavour's OMS engines. It is being discussed.

During this built-in hold, all computer programs in the Firing Room of the Complex 39 Launch Control Center will be verified to ensure that the proper programs are available for the countdown; the landing convoy status will be verified and the landing sites will be checked to support an abort landing during launch today; the Inertial Measurement Unit preflight alignment will be verified completed; and preparations are made to transition the orbiter onboard computers to Major Mode 101 upon coming out of the hold. This configures the computer memory to a terminal countdown configuration.

2221 GMT (6:21 p.m. EDT)

Commander Ken Cockrell is pressurizing the gaseous nitrogen system for Endeavour's Orbital Maneuvering System engines, and pilot Paul Lockhart is activating the gaseous nitrogen supply for the orbiter's Auxiliary Power Units' water spray boilers.

2219 GMT (6:19 p.m. EDT)

The ground pyro initiator controllers (PICs) are scheduled to be powered up at this time in the countdown. They are used to fire the solid rocket hold-down posts, liquid oxygen and liquid hydrogen tail service mast and external tank vent arm system pyros at liftoff and the space shuttle main engine hydrogen gas burn system prior to engine ignition.

Endeavour's two Master Events Controllers also are being tested. They relay the commands from the shuttle's computers to ignite, and then separate the boosters and external tank during launch.

2214 GMT (6:14 p.m. EDT)

"It's a very dynamic day out there," says the Air Force weather officer here in the Kennedy Space Center. The anvil clouds from thunderstorms are beginning to get pretty close to the Cape. He says the one real hope left is the storms would begin to die off. Launch is still 90 minutes away, so officials will continue to watch, wait and keep their fingers crossed.

2206 GMT (6:06 p.m. EDT)

The Ground Launch Sequencer mainline activation has been completed. Also at this point in the countdown, the Air Force Eastern Range shuttle safety system terminal count closed-loop test will be performed to verify the countdown can be stopped in the final seconds before liftoff should a safety issue arise.

2156 GMT (5:56 p.m. EDT)

Endeavour's crew module hatch has swung shut and Orbiter Closeout Crew is working to latch it. Pressure and leak checks will be performed shortly to ensure a good seal on the hatch for today's launch, which is now just under two hours away at 7:44 p.m. EDT.

2149 GMT (5:49 p.m. EDT)

T-minus 1 hour and counting. The pre-flight alignment of Endeavour's Inertial Measurement Units is now beginning, and will be completed by the T-minus 20 minute hold. The IMUs were calibrated over the past few hours of the countdown. The three units are used by the onboard navigation systems to determine the position of the orbiter in flight.

Meanwhile, the S-band antennas at the MILA tracking station here at the Cape are shifting from low power to high power. The site will provide voice, data and telemetry relay between Atlantis and Mission Control during the first few minutes of flight. Coverage then is handed to a NASA Tracking and Data Relay Satellite in space.

2145 GMT (5:45 p.m. EDT)

The optimism among the weather forecasters is slipping away. Most of the state of Florida is covered by thunderstorms at this hour with the exception of the Cape itself. However, the storms and anvil clouds are drifting in the direction of Kennedy Space Center. In all likelihood it's going to be a down-to-the-wire call tonight. But at this point there isn't a great deal of hope being held by the meteorologists.

2135 GMT (5:35 p.m. EDT)

The Orbiter Closeout Crew is preparing to exit Endeavour's crew module in preparation for closing the hatch for flight.

2105 GMT (5:05 p.m. EDT)

With all seven astronauts aboarded the shuttle, the countdown rolls along at Kennedy Spacce Center today for liftoff at 7:44:26 p.m. EDT. There are no technical problems being addressed. The only concern is the weather -- specifically thunderstorms.

At this point in the count, the ground launch sequencer software that will control the final nine minutes of the countdown will be initialized.

Also, the solid rocket boosters' gas generator heaters in the hydraulic power units are turned on, the aft skirt gaseous nitrogen purge is starting and the rate gyro assemblies (RGAs) are being activated. The RGAs are used by the orbiter's navigation system to determine rates of motion of the boosters during the first-stage flight.

2102 GMT (5:02 p.m. EDT)

Mission specialist Franklin Chang-Diaz, set for the record-matching seventh space flight, has now boarded Endeavour. All seven astronauts are now inside the shuttle for launch.

2054 GMT (4:54 p.m. EDT)

The commander of Expedition 5 -- the fifth resident crew to live aboard the International Space Station -- Russian cosmonaut Valeri Korzun is now inside Endeavour.

2051 GMT (4:51 p.m. EDT)

Endeavour mission specialist Philippe Perrin of the French space agency has now made his way into the shuttle.

2044 GMT (4:44 p.m. EDT)

Now three hours away from launch time. All weather rules at Kennedy Space Center are currently "go" for liftoff.

2036 GMT (4:36 p.m. EDT)

Expedition 5 astronaut Peggy Whitson and pilot Paul Lockhart have now climbed aboard space shuttle Endeavour

2032 GMT (4:32 p.m. EDT)

Commander Ken Cockrell and Expedition 5 crew member Sergei Treschev are already onboard the shuttle.

2030 GMT (4:30 p.m. EDT)

NASA has lifted the remaining secrecy surrounding the countdown by announcing the Endeavour astronauts have arrived at launch pad 39A.

The crew took the elevator to the 195-foot level of the pad structure where the Orbiter Access Arm is located with the White Room. In the White Room the crew will be outfitted with the rest of their gear and communications hat before entering Endeavour's crew module hatch.

2020 GMT (4:20 p.m. EDT)

The crew should be at the pad by now. However, NASA won't begin it's live launch coverage until 4:30 p.m.

2002 GMT (4:02 p.m. EDT)

With a chopper and NASA security escort, the crew aboard the AstroVan has just driven past the press site on their way to launch pad 39A. The convoy stopped briefly in front of the Launch Control Center for managers to get out of the AstroVan and make their way into the Firing Room. Also, Chief Astronaut Charlie Precourt jumped out and will head to the Shuttle Landing Facility to begin weather reconnaissance flights in a T-38 jet and later in the Shuttle Training Aircraft.

1949 GMT (3:49 p.m. EDT)

T-minus 3 hours and counting. The countdown has resumed on scheduled from this planned two-hour built-in hold. Clocks will now tick down to T-minus 20 minutes when the next hold is planned. A final hold is scheduled at the T-minus 9 minute mark. Liftoff remains set for 7:44:26 p.m. EDT.

There are no technical problems being reported by NASA. The weather is still a concern due to thunderstorms around Central Florida today.

1940 GMT (3:40 p.m. EDT)

The Air Force weather official here in the Kennedy Space Center news center says there are a lot of thunderstorms forming over the western part of Florida. They are moving to the east and it'll just be a close watch on how the storms track over the next few hours. The hope is the storms have formed early enough to dissipate in time for launch at 7:44 p.m. EDT. Right now, weather is "go" at KSC.

1923 GMT (3:23 p.m. EDT)

All the launch weather rules are now "go" across the board.

1919 GMT (3:19 p.m. EDT)

Now 30 minutes remaining in this built-in hold at the T-minus 3 hour mark. The astronauts -- per the standard timeline -- should be starting to suit up in preparation for heading to the launch pad over the next hour.

1910 GMT (3:10 p.m. EDT)

The crew of space shuttle Endeavour will now receive a routine pre-flight weather briefing with flight controllers in Houston. Weather continues to look like it will go down to their wire today at Kennedy Space Center due to thunderstorms.

Currently, the field mills are registering acceptable charge in the air. But thick clouds and thunderstorm debris clouds are violating launch rules at the moment.

The astronauts' launch day schedule is mostly a secret. Under NASA's new security policy, the crew members' movements won't be revealed until after they have arrived at the launch pad.

1845 GMT (2:45 p.m. EDT)

There are now three weather rules that are being violated -- the rule against launching through thick clouds, thunderstorm debris clouds and the field mills remain "no go".

1818 GMT (2:18 p.m. EDT)

The latest check on the weather criteria shows all conditions are currently "go" except for the field mills, which are "red" at this time. The field mills measure the electrical charge in the air.

There are a lot of clouds around Central Florida this afternoon, but it is partly cloudy directly overhead Kennedy Space Center.

1810 GMT (2:10 p.m. EDT)

T-minus 3 hours and holding. Countdown clocks are currently in a planned two-hour built-in hold. The pause began at 1:49 p.m. Liftoff of Endeavour remains scheduled for 7:44:26 p.m. EDT today from launch pad 39A at the Kennedy Space Center in Florida. There are no problems to report at this time.

Following tanking procedures, a team called the Final Inspection Team was dispatched to the pad to check the vehicle one last time prior to liftoff. The six-person team, comprised of five engineers and one safety official, is currently performing the inspections at pad 39A. At the conclusion of their two-hour tour-of-duty, they will have walked up and down the entire fixed service structure and mobile launcher platform.

The team is on the lookout for any abnormal ice or frost build-up on the vehicle that could break-off during ignition and damage the spacecraft. The team is also searching for any loose debris that could possibly fly up and strike the vehicle at launch. And the third item of interest to the team is the thermal integrity of the external tank foam insulation.

The team uses a portable infrared scanner that gathers temperature measurements on the surface area of the shuttle and can spot leaks. The scanner will be used to obtain temperature data on the external tank, solid rocket boosters, space shuttle orbiter, main engines and launch pad structures. The scanner can also spot leaks of the cryogenic propellants, and due to its ability to detect distinct temperature differences, can spot any dangerous hydrogen fuel that is burning. One team member is also responsible for photo documentation.

Each member of the Final Inspection Team is in constant contact with NASA Test Director Steve Altemus in the Firing Room.

The team wears the highly visible day-glow orange coveralls that are anti-static and flame resistant. Each member also has a self-contained emergency breathing unit that holds about 10 minutes of air.

Following the Final Inspection Team's activities, they will meet with NASA Launch Director Mike Leinbach, the Mission Management Team, and engineering directors in the launch control center, providing a detailed report on the inspections and findings at the pad 39A.

A full inspection of the vehicle and pad was performed yesterday and the external tank received a thorough check prior to fueling today.

An inspection of the launch pad and beach will be made following launch. That inspection will be to look for anything unusual, particularly anything that could have fallen off of the vehicle during the first few seconds of flight. Later, there will be a meeting to review high-speed videotape and film of the launch and early ascent to determine if there was any damage to the vehicle.

1745 GMT (1:45 p.m. EDT)

Endeavour's external fuel tank is now full with 528,000 gallons of super-cold liquid oxygen and liquid hydrogen. Tanking was officially completed at about 1:26 p.m. EDT.

But given the cryogenic nature of the oxidizer and propellant, the supplies naturally boil away. So the tanks are continuously topped off until the final minutes of the countdown in a procedure called "stable replenishment."

With the hazardous tanking operation completed, the Orbiter Closeout Crew and Final Inspection Team are being dispatched to the pad to perform their jobs. The closeout crew will ready Endeavour's crew module for the astronauts' boarding in a couple of hours; and the inspection team will give the entire vehicle a check for any ice formation from fueling.

1600 GMT (12:00 p.m. EDT)

Fueling operations are now passing the half-way mark. NASA is not reporting any problems as the countdown continues to today's 7:44 p.m. EDT launch.

1420 GMT (10:20 a.m. EDT)

The high-speed pumping of a half-million gallons of super-cold rocket fuel into space shuttle Endeavour for launch has begun. The three-hour operation to load the super-cold liquid oxygen and liquid hydrogen officially began at 10:32 a.m. EDT.

There are actually two tanks inside the shuttle's orange bullet-shaped tank. The liquid oxygen tank fills the top third of the external tank. It will be filled with 143,000 gallons of liquid oxygen chilled to minus 298 degrees Fahrenheit (minus 183 degrees Celsius). The liquid hydrogen tank is contained in the bottom two-thirds of the external tank. It holds 385,000 gallons of liquid hydrogen chilled to minus 423 degrees Fahrenheit (minus 253 degrees Celsius).

The cryogenics are pumped from storage spheres at the pad, through feed lines to the mobile launcher platform, into Endeavour's aft compartment and finally into the external fuel tank.

The fueling process is being orchestrated by engineers in the safe confines of the Kennedy Space Center's Launch Control Center located about three-and-a-half miles from Endeavour at launch pad 39A.

NASA officials are not reporting any technical problems this morning as the countdown continues on schedule for today's planned 7:44:26 p.m. EDT launch time.

The weather forecast is the only real question mark with a 60 percent chance thunderstorms will prohibit liftoff this evening during the 10-minute launch window of 7:39 to 7:49 p.m. EDT. However, meteorologists say there is hope that the storms, which will form over the central part of Florida, will dissipate before reaching the coast.

Meanwhile, weather at the abort landing sites in Spain, Morocco, California and New Mexico all look favorable.

1420 GMT (10:20 a.m. EDT)

The launch team has been given a "go" to begin fueling space shuttle Endeavour for today's liftoff. Confirmation that the loading of 528,000 gallons of super-cold liquid hydrogen and liquid oxygen has commenced will be received momentarily.

There are no technical problems being worked and the weather forecast remains unchanged with a 60 percent chance of acceptable conditions at today's 7:44:26 p.m. EDT launch time.

1330 GMT (9:30 a.m. EDT)

Mission managers are convening their "pre-tanking meeting" at Kennedy Space Center to review the progress of work at launch pad 39A and the weather before giving engineers approval to begin fueling Endeavour this morning. The loading of the shuttle's external fuel tank is expected to start in about an hour.

WEDNESDAY, MAY 29, 2002
2200 GMT (6:00 p.m. EDT)

Here is a look at some of the key countdown milestones leading to launch of Endeavour at 7:44:26 p.m. EDT (2344:26 GMT) Thursday.

The countdown is current in a scheduled built-in hold at the T-11 hour mark. activities planned tonight:

• Flight crew equipment late stow
• Move Rotating Service Structure to the park position (about 11:30 p.m.)
• Perform ascent switch list
• Fuel cell flow-through purge complete

• Resume countdown at T-11 hours (3:49 a.m.)
• Activate the orbiter's fuel cells (4:59 a.m.)
• Clear the blast danger area of all non-essential personnel
• Switch Endeavour's purge air to gaseous nitrogen (6:04 a.m.)
• Enter planned two-hour built-in hold at the T-6 hour mark (8:49 a.m.)
• Launch team verifies no violations of launch commit criteria prior to cryogenic loading of the external tank
• Clear pad of all personnel
• Begin three-hour loading the external tank with about 500,000 gallons of cryogenic propellants (about 10:19 a.m.)
• Resume countdown at T-6 hours (10:49 a.m.)
• Enter planned two-hour built-in hold at T-3 hours (1:49 p.m.)

Watch this page for complete live coverage throughout the day on Thursday beginning with the start of fueling.

2100 GMT (5:00 p.m. EDT)

NASA has just announced the actual launch window and target liftoff time for Thursday's blastoff of space shuttle Endeavour. Under the space agency's new security policy, officials won't reveal the precise times until about 24 hours in advance.

The launch window opens at 7:39:27 p.m. EDT and extends for nearly 10 minutes to 7:49:25 p.m. EDT. The preferred launch time -- when the plane of the International Space Station's orbit passes directly over the pad -- is 7:44:26 p.m. EDT (2344:26 GMT).

All of our mission timeline charts are being updated to reflect the actual launch time. Use the pull-down menu above to reach those other pages.

1600 GMT (12:00 p.m. EDT)

With no technical problems at pad 39A, the shuttle Endeavour's countdown continues to tick smoothly toward launch Thursday on a space station crew rotation mission. But forecasters say the weather outlook hasn't changed and there's still a 60 percent chance of thunderstorms that could force a delay. Read full story.

1320 GMT (9:20 a.m. EDT)

Endeavour's three electricity-generating fuel cells have been loaded with their supplies of liquid hydrogen and liquid oxygen to power the 12-day mission as the countdown rolls on at Kennedy Space Center for Thursday evening's launch.

"The countdown is continuing in progress," NASA test director Pete Nickolencko said this morning. "We are right on schedule and we are tracking no technical issues."

Yesterday, the launch team completed checks of the shuttle's avionics and then began the multi-hour job of filling the fuel reactant tanks located beneath the shuttle's payload bay.

Final system checks on the three main engines are currently underway. The rest of today will be spent securing launch pad 39A and readying the Rotating Service Structure for its rollback from around Endeavour later tonight.

Air Force weather forecasters are still calling for a 40 percent chance conditions will be favorable for an on-time launch. Thunderstorms are the main concern.

The forecast for Friday and Saturday calls for a 30 percent chance of launching either day, also due to thunderstorms.

NASA will announce the actual launch time late this afternoon, ending its self-imposed security blackout on the countdown. At this point, all that is officially known is Endeavour will launch sometime between 4 and 8 p.m. EDT Thursday. We'll post the launch time and available window on this page when the announcement is made.

WEDNESDAY, MAY 29, 2002

The primary goal of Endeavour's mission, scheduled for launch Thursday, is to ferry a fresh three-person crew to the international outpost - the fifth set of full-time residents since permanent occupation began in November 2000 - and to deliver science equipment, fresh food, water and other supplies. Plus, two spacewalking surgeons will operate on the station's $600 million robot arm, bolting on a replacement joint to fix what amounts to a broken wrist. Read complete mission preview.

TUESDAY, MAY 28, 2002

The shuttle Endeavour's countdown began ticking late Monday night for launch Thursday on a space station crew rotation and robot arm repair mission. There are no technical problems at pad 39A, but forecasters say there's a 60 percent chance of a launch delay because of thundershowers. Read full story.

1320 GMT (9:20 a.m. EDT)

The countdown has started and the seven astronauts have arrived at Kennedy Space Center for Thursday's launch aboard space shuttle Endeavour, NASA officially confirmed this morning.

There are no technical problems being worked as preparations continue for the liftoff, which will occur sometime between 4 and 8 p.m. Thursday. The exact launch time and 10-minute launch window won't be announced until 24 hours in advance as part of the agency's security policy to thwart a terrorist attack.

The only concern for an on-time launch, as it always seems to be, is the weather. Meteorologists are predicting thunderstorms around the Cape, meaning there is only a 40 percent chance of acceptable weather for launch time.

Should the launch slip to Friday or Saturday, thunderstorms are again forecast and just a 30 percent chance of launching either day.

MONDAY, MAY 27, 2002

The standard three-day launch countdown for Endeavour's Thursday blastoff to the International Space Station is believed to have started today as planned. As part of NASA's new security measures, the space agency won't announce the fact countdown clocks are ticking at Kennedy Space Center until a 9 a.m. EDT status briefing Tuesday.

Meanwhile, the leak checks on the new water spray boiler valve were successfully completed this evening with no problems reported.

SUNDAY, MAY 26, 2002
1350 GMT (9:50 a.m. EDT)

Final installation of the new valve was completed last night. Testing is planned for today.

Launch of Endeavour is still set to occur Thursday between 4 and 8 p.m. EDT. The exact liftoff time will be announced 24 hours in advance.

The three-day launch countdown will begin in secrecy sometime Monday. Confirmation that the count is underway is not expected until Tuesday morning.

SATURDAY, MAY 25, 2002
2145 GMT (5:45 p.m. EDT)

The old water spray boiler valve was removed this morning and by late this afternoon engineers said the new valve had been put into the shuttle. The final hook up of valve will be performed after some testing later this evening.

1245 GMT (8:45 a.m. EDT)

Sources say removal and replacement of the leaky valve on Endeavour's water spray boiler No. 3 is now underway at launch pad 39A. The job is expected to extend into the afternoon.

For our Spaceflight Now Plus subscribers, we present several hours of video to give the most detailed preview of Endeavour's mission as well as the Expedition 5 crew's voyage to the International Space Station:

Video coverage for subscribers only:
   VIDEO: DETAILED OVERVIEW OF ENDEAVOUR'S FLIGHT QT or RV
   VIDEO: PREVIEW OF MISSION'S THREE SPACEWALKS QT or RV
   VIDEO: PREVIEW OF THE EXPEDITION 5 MISSION QT or RV
   VIDEO: PRE-FLIGHT BRIEFING WITH EXPEDITION 5 CREW QT or RV
   VIDEO: MEET THE FULL SHUTTLE/STATION CREW QT or RV
   VIDEO: TOUR ENDEAVOUR'S PAYLOAD BAY QT or RV
   VIDEO: ANIMATION OF SHUTTLE DOCKING TO STATION QT or RV
   VIDEO: ITALIAN CARGO MODULE ATTACHED TO STATION QT or RV
   VIDEO: ANIMATION OF MOBILE BASE SYSTEM INSTALLED QT or RV
   VIDEO: ANIMATION OF CARGO MODULE BEING REMOVED QT or RV
   VIDEO: ANIMATION OF ENDEAVOUR'S UNDOCKING QT or RV

1145 GMT (7:45 a.m. EDT)

Technicians will spend much of today replacing at least one leaky valve deep inside space shuttle Endeavour so the ship can remain on schedule for launch Thursday to rotate the resident crews living aboard the International Space Station.

Engineers climbed into the shuttle's aft compartment last night to determine if they could even access the valves on water spray boiler No. 3 -- the device used to cool Endeavour's auxiliary power unit No. 3 during launch and reentry. See graphic.

Recent tests showed at least one valve was leaking on the water spray boiler, prompting the never-before-attempted replacement on the launch pad.

Sources say today's valve replacement job will take 6 to 8 hours.

Meanwhile, preparations are still on schedule to begin Endeavour's launch countdown sometime Monday in advance of Thursday evening's liftoff from pad 39A at the Kennedy Space Center. Although NASA won't announce the shuttle's exact launch time until 24 hours beforehand due to security reasons, the space agency says liftoff will occur between 4 and 8 p.m. EDT (2000-0000 GMT).

We'll update this page as more information becomes available.

FRIDAY, MAY 24, 2002

Engineers plan to climb into the shuttle Endeavour's main engine compartment tonight to assess the feasibility of replacing one or more valves associated with one of the ship's three hydraulic system water spray boilers. If the workers cannot gain access, NASA could be forced to postpone next Thursday's launch and haul the shuttle back to its processing hangar for repairs.
Read full story.

Read our earlier status center coverage.