BY JUSTIN RAY

October 11, 2000 -- Follow the pre-flight preparations and mission of space shuttle Discovery further the construction of the international space station. Reload this page for the very latest on the mission.

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

Meterologists continue to assess weather conditions at Edwards Air Force Base in California as Discovery takes another spin around Earth. Forecasters are still concerned about low clouds over the runway that would obscure commander Brian Duffy's view during final approach and rainshowers moving into the area that would damage the shuttle if the spaceship flew through the precipitation. A decision whether to allow Discovery to descend from orbit for this final landing opportunity today will be made by 2209 GMT (6:09 p.m. EDT).

If Discovery is cleared for landing, the twin orbital maneuvering system engines would be fired for about three minutes starting at 2229 GMT (6:29 p.m. EDT) to break from orbit. Touchdown would occur at 2335 GMT (7:35 p.m. EDT).

Should the weather remain unacceptable, Discovery will remain in space yet another day and try to land tomorrow at either Kennedy Space Center in Florida or at Edwards. KSC's weather on Tuesday is still iffy but Edwards is greatly improved.

2048 GMT (4:48 p.m. EDT)

See the ground track Discovery would follow to Edwards on orbit 188.

2033 GMT (4:33 p.m. EDT)

ONE MORE ORBIT. Entry Flight Director Leroy Cain has decided to keep Discovery in space for at least one more orbit due to rainshowers moving toward the restricted 30-mile circle around Edwards Air Force Base in California. NASA has one final opportunity for Discovery to return to Earth today, which would occur on orbit 188 with a deorbit burn at 2229 GMT (6:29 p.m. EDT) and landing at 2335 GMT (7:35 p.m. EDT).

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

Weather conditions at Edwards Air Force Base remain "no go" for landing. Dark clouds can be seen moving around the base, replacing the clearing skies from earlier this afternoon. Mission Control should make a final ruling on the upcoming landing opportunity in the next few minutes which would begin with a deorbit burn at 2051 GMT (4:51 p.m. EDT) and touchdown at 2158 GMT (5:58 p.m. EDT). There is one additional chance to land today on the following orbit 90 minutes later.

2020 GMT (4:20 p.m. EDT)

If Discovery is cleared for touchdown at Edwards Air Force Base in California today it would mark the first shuttle landing there in over four years. The last 23 straight landings have occurred at Kennedy Space Center in Florida. Space shuttle Atlantis made the most recent Edwards landing on March 31, 1996 to conclude the STS-76 flight that marked the third docking mission to the Russian space station Mir. In fact 30 of the last 31 shuttle missions finished with Florida landing, which NASA prefers because its saves $1 million and a week's worth of processing time to avoid ferrying the shuttle across the country to the KSC launch site.

In the 98 previous shuttle landings, 52 have occurred at KSC, 45 at Edwards and one at White Sands in New Mexico.

2008 GMT (4:08 p.m. EDT)

Discovery's astronauts are basically complete with their deorbit preparation checklist, which began earlier this morning.

With the entry checklist now opened, the crew has performed a steering check of the orbital maneuvering system engine nozzles needed for the upcoming deorbit burn. Also, switches in the cockpit were flipped to pre-start the shuttle's three Auxiliary Power Units used to drive the shuttle's hydraulics for moving the wing flaps, deploying the landing gear and steering the nose wheel upon touchdown.

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

Meteorologists are now keeping a close eye on some rainshowers to the east of Edwards Air Force Base in California. The rain must remain 30 nautical miles away from the runway in order for Discovery to be permitted to land. Low clouds are still a concern, too.

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

Mission Control has instructed the astronauts to begin the "fluid loading" procedure in which each crew member drinks large amounts of liquids to aid in readapting to Earth's gravity. This is a major signal that flight controllers believe there is a real chance of getting Discovery home today.

CAPCOM Dom Gorie just told Discovery commander that the forecast for Edwards Air Force Base remains "no go" due to a low cloud ceiling and there is continued concern with a cloud system to the east of the California military complex. However, Gorie said the team is staying cautiously optimistic.

1930 GMT (3:30 p.m. EDT)

Now about an hour away from the point Entry Flight Director Leroy Cain will have to decide whether weather conditions are acceptable for Discovery to make a landing at Edwards Air Force Base in California, touching down on orbit 187 at 2158 GMT (5:58 p.m. EDT). Cain could also decide to keep Discovery aloft for another orbit a shoot for the day's final landing opportunity at Edwards with touchdown at 2335 GMT (7:35 p.m. EDT). The skies are looking a lot better now than they did earlier this morning.

1910 GMT (3:10 p.m. EDT)

NASA astronaut Kent Rominger is flying the Shuttle Training Aircraft around Edwards Air Force Base in California's Mojave Desert for weather reconnaissance. The STA is a modified Gulfstream jet that features flying characteristics of the space shuttle, allowing Rominger to provide first-hand observations of how the weather conditions might affect Discovery's landing.

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

Aboard shuttle Discovery the astronauts are continuing with work to prepare the shuttle for its trip back to Earth. They are deactivating the craft's star trackers and closing the doors on the shuttle's nose, and also verifying switches in Discovery's cockpit are in the correct positions. In the next little while the crew will put on their day-glow orange launch and entry partial pressure suits.

If weather conditions improve sufficiently and NASA gives approval for landing, Discovery will fires its breaking rockets at 2051 GMT (4:51 p.m. EDT) for three minutes to deorbit and begin an hour-long trek back through the atmosphere. Touchdown on Runway 22 at Edwards Air Force Base in California is scheduled for 2158 GMT (5:58 p.m. EDT).

1835 GMT (2:35 p.m. EDT)

The astronauts are transitioning the shuttle's flight control computers from the in-orbit OPS-2 software to the OPS-3 software package that governs the shuttle's reentry and landing. The crew is marching through the standard pre-landing activities in hopes weather will allow Discovery to return to Earth at Edwards Air Force Base in California today at 2158 GMT (5:58 p.m. EDT).

1819 GMT (2:19 p.m. EDT)

Discovery's twin payload bay doors have been closed and latched in preparation for the shuttle's possible entry and landing today.

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

Holding out a glimmer of hope weather conditions will improve at Edwards Air Force Base later tonight, Mission Control has given the Discovery astronauts a "go" to close the shuttle's payload bay doors. The forecast remains unacceptable for a landing at Edwards at 2158 GMT (5:58 p.m. EDT) due to a low cloud ceiling. However, meteorologists report that satellite imagery shows the clouds thinning a bit. Plus there is plenty of time for conditions to improve because a final decision to commit to landing won't have to be made until around 2040 GMT (4:40 p.m. EDT).

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

NASA has decided to skip the first of three landing opportunities today at Edwards Air Force Base because bad weather. Landing would have occurred on orbit 186 at 2023 GMT (4:23 p.m. EDT). The Calfornia military base currently has a low cloud ceiling at 6,000 feet, icing conditions over the field and moisture within 30 miles, all of which are constraints for the shuttle's homecoming.

The weather will be watched and if conditions should improve, Discovery could shoot for a touchdown at 2158 GMT (5:58 p.m. EDT) at Edwards on orbit 187. A final landing opportunity today is on orbit 188 with a 2335 GMT (7:35 p.m. EDT) touchdown.

"The forecast is going to stay the same, with a chance of rain showers within 30," CAPCOM Dom Gorie told Discovery's crew in waiving off the first Edwards opportunity. "So if we want to optimize for two opportunities into Edwards today the best plan is to bypass this rev 186 and shoot for 187 and 188. They're certainly better than we currently have.

"The overall plan is to maintain that opportunity to look at three deorbit revolutions tomorrow because the weather at Edwards is markedly better than it is today. So we're going to terminate the 186 opportuniity, to give you another hour and a half of window time, and we wanted to save you some in-the-suit time as well."

Commander Brian Duffy replied: "That sounds like a good plan. We could tell you guys were working it ... and we were already figuring this rev was probably not going to be a go. We're ready to support the other two, that's not a problem."

Meanwhile, officials have formally ruled out the second of two Kennedy Space Center opportunities today due to high crosswinds. KSC had landing attempts possible on orbits 185 and 186 today.

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

Astronaut Dom Gorie in Mission Control just radioed Discovery and told the crew that meteorologists are still watching the weather at Edwards Air Force Base where conditions are forecast "marginal at best" today. A decision on how to proceed is expected shortly.

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

Now about one hour away from the point Mission Control will need to decide whether or not to close shuttle Discovery's payload bay doors and have the seven astronauts begin suiting up in preparation for making the first landing opportunity today at Edwards Air Force Base in California. The target landing time is 2023 GMT (4:23 p.m. EDT).

Officials will be receiving an updated weather forecast before making the decision to press ahead with closing the 60-foot-long payload bay doors. The current forecast is calling for low clouds and a chance of rain at Edwards this afternoon, which would prevent a landing.

The astronauts entered the deorbit prep timeline earlier this morning but was halted activities when officials waived off the first landing attempt at Kennnedy Space Center due to high crosswinds. Since conditions were not forecast to improve today or tomorrow in Florida, NASA decided to target the backup landing site at Edwards to bring Discovery back to Earth.

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

NASA has given up on Kennedy Space Center and will now focus on the backup landing site at Edwards Air Force Base for bringing shuttle Discovery back to Earth today.

The shuttle runway at KSC currently has a crosswind of 14 peaking to 24 knots, well above the limit of 15 knots, and conditions are not forecast to improve today. There are two opportunities to land in Florida this afternoon and although only the first have been officially waived off there is little likelihood the winds would abate sufficiently for the second attempt.

So all activities in space aboard the shuttle and at Mission Control are geared toward a scheduled 2023 GMT (4:23 p.m. EDT) landing of Discovery on Runway 04 at Edwards Air Force Base in California's Mojave Desert. However, a low cloud ceiling at 7,000 feet and a slight chance of rain with 30 miles currently makes the forecast "no go" at Edwards. There is a second opportunity at Edwards one orbit later with a touchdown expected at 2158 GMT (5:58 p.m. EDT).

1330 GMT (9:30 a.m. EDT)

The Discovery astronauts were awakend at 6:17 a.m. today for a second attempt to bring their space station assembly flight to a close. The astronauts currently are working through the landing day deorbit timeline, rigging the shuttle for re-entry, while flight controllers in Houston keep tabs on high winds in Florida and low clouds in California that could prompt another 24-hour delay.

Commander Brian Duffy and his six crewmates have five landing opportunities today on four successive orbits, two at the Kennedy Space Center and three at Edwards Air Force Base in California's Mojave Desert. The first landing opportunity is to Kennedy, with a deorbit rocket firing at 1:42:45 p.m. for a touchdown on runway 33 at 2:51:15 p.m. The day's final landing opportunity is at Edwards at 7:35 p.m. EDT.

The forecast for Kennedy calls for winds out of 50 degrees - almost pure crosswind - at 15 knots with gusts to 25 knots. In addition, there's a chance a deck of broken clouds will develop at 4,000 feet. NASA's flight rules restrict end-of-mission daylight landings to 15 knots and broken decks must be above 8,000 feet.

At Edwards, the winds are not a problem but forecasters are expecting a broken deck of clouds at 7,000 feet and a slight chance of rain showers within 30 miles of the runway, which would violate NASA's flight rules.

Conditions are expected to worsen Tuesday in Florida, but improve dramatically in California.

Mission control commentator James Hartsfield says entry flight director Leroy Cain will evaluate the latest weather forecasts in about an hour and a half before deciding whether to close Discovery's cargo bay doors and make a run at the first Florida opportunity. At this point, that seems doubtful barring a major change in the weather.

The end-of-mission daylight landing flight rules are posted on the Landing Weather Forecast page.

SUNDAY, OCTOBER 22, 2000
1857 GMT (2:57 p.m. EDT)

With crosswinds gusting to nearly 20 knots, NASA was forced to delay the shuttle Discovery's planned return to Earth today by at least 24 hours. Even worse weather is expected at the Kennedy Space Center on Monday, raising the prospect of a diversion to California or, more likely, yet another mission extension to Tuesday. Read our wrap-up story for a full summary of the landing delay.

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

WAIVE OFF! High crosswinds at Kennedy Space Center will keep space shuttle Discovery in orbit for another day. The strong winds are persistent and forecast to remain out of limits for both of today's available landing opportunities.

Monday's forecast in Florida is not much better with crosswinds again a concern along with low clouds and a chance of rainshowers. The backup landing site at Edwards Air Force Base in California will be activated tomorrow and is expected to have acceptable weather. However, NASA would rather have Discovery land at Kennedy Space Center to save a week's worth of time it takes to ferry the shuttle across the country. See our chart of landing opportunities.

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

The weather picture continues to look lousy at Kennedy Space Center where a stiff, steady crosswind is blowing across the three-mile-long shuttle runway. Winds are currently coming from the northeast at 13 peaking to 19 knots, well above the limit of 15 knots. Mission Control has told commander Brian Duffy it was his call whether to begin the "fluid loading" procedure whereby the astronauts drink large amounts of water to aid in readapting to Earth's gravity.

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

The latest weather update from meteorologists at Mission Control report the crosswinds at Kennedy Space Center's Shuttle Landing Facility are currently measured at 17 knots, which is above NASA's limit of 15 knots. In addition, forecasters say they don't see anything that is going to dramatically change the wind direction or reduce the velocity, according to spokesman Kyle Herring. But flight controllers are pressing ahead with the day's schedule and don't need to make a final decision on the first of two landing opportunities until around 12:45 p.m. EDT.

1509 GMT (11:09 a.m. EDT)

Space shuttle Discovery's 60-foot-long payload bay doors have been closed and the onboard computers are transitioning to the OPS-3 software program that governs entry and landing.

1425 GMT (10:25 a.m. EDT)

Forecasters with the Spaceflight Meteorology Group at the Johnson Space Center say high crosswinds are developing at the Kennedy Space Center that likely will impact today's landing of the shuttle Discovery. The crew was updated on the latest weather just before 9:50 a.m.

"Houston, Discovery, a couple of questions, one is what runway do you think we're going to be looking at?" asked commander Brian Duffy.

"Brian, our first look at it is runway one five," said astronaut communicator Dominic Gorie in mission control.

"OK, we're just setting the channels up here. And just if you could, could you clue us in on how the winds are looking about now?"

"Brian, they're looking pretty solid with the prediction out of zero-five-zero (degrees)," Gorie replied. "We're expecting them to get up to 17 to 18 knots on the peak and right now, they're about 12 to 13."

"OK, sounds good, thanks."

NASA's end-of-mission crosswind safety limit is 15 knots and for the shuttle's 3-minute-long runway, winds out of 60 degrees represent a pure crosswind. As a result, an 18-knot crosswind from 50 degrees would be almost all right crosswind and represent a flight rule violation.

But the astronauts are pressing ahead in hopes conditions will improve. The shuttle's payload bay doors will be closed in a few minutes and if all goes well, Discovery's braking rockets will be fired at 1:07 p.m. to begin the hour-long descent to Earth.

The astronauts were awakened at 6:17 a.m. to begin landing preparations. The crew has two landing opportunities today at the Kennedy Space Center with the first at 2:14:20 p.m. and the second at 3:49:59 p.m.

"Good morning, Discovery, and welcome to what we hope is the landing day," radioed astronaut Gerhard Thiele from mission control.

Entry flight director Leroy Cain said Saturday if Discovery's crew fails to make it back to Florida today, the astronauts will remain in orbit an extra day and try again Monday. At that point, depending on the forecast, NASA may activate Edwards Air Force Base, Calif., as a backup landing site.

The forecast currently calls for worsening conditions in Florida on Monday and Tuesday with improving conditions at Edwards. Discovery has enough propellant, electrical power and carbon dioxide absorbent to remain in space until Wednesday in a worst-case scenario.

NASA managers want to get Discovery back on the ground in Florida if at all possible to avoid disruptions in the space station assembly schedule. The ship's next flight is a high-profile mission early next year to deliver the station's second full-time crew and to bring its first crew back to Earth.

A landing at Edwards would cost the agency about $1 million and add more than a week to the shuttle's ground processing flow.

Assuming the weather cooperates today, this will be the 53rd shuttle landing at the Kennedy Space Center and the 24th in a row. The most recent landing at Edwards occurred on March 31, 1996.

SATURDAY, OCTOBER 21, 2000

Keeping tabs on high winds in Florida, the Discovery astronauts tested the shuttle's re-entry systems, packed up loose gear and squeezed in a final bit of "window time" today as they set their sights on landing Sunday at the Kennedy Space Center. Read our full story.

2002 GMT (4:02 p.m. EDT)

The seven-member crew of shuttle Discovery just held the traditional in-flight news conference with reporters gathered at Johnson Space Center in Houston and Kennedy Space Center in Florida. We will have a complete story on the event a little later this afternoon.

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

Shuttle commander Brian Duffy, pilot Pamela Melroy and flight engineer William McArthur tested Discovery's re-entry systems today as their crewmates stowed gear and readied the ship for landing Sunday at the Kennedy Space Center.

For the flight control system checkout, which began shortly after 10 a.m., Duffy and Melroy fired up one of the shuttle's hydraulic power systems and confirmed the orbiter's steering system is in good shape and ready for entry. They also fired all 44 of the shuttle's small steering jets in a routine pre-landing checkout. No problms were found with any of the critical systems.

Discovery's crew has two landing opportunities Sunday, on successive orbits, at 2:14 p.m. and 3:50 p.m. Forecasters currently predict generally favorable conditions, although crosswinds from the northeast at up to 15 knots - right at NASA's safety limit - could cause problems. But NASA managers are hopeful the winds will cooperate and that Duffy can bring Discovery home on schedule.

NASA is not staffing Edwards Air Force Base, Calif., Sunday. But if Discovery is forced to remain in orbit an extra day, mission managers will reconsider whether to activate Edwards for landing attempts Monday. Program managers want to get Discovery back on the ground in Florida as soon as possible to turn the orbiter around for its next mission, a high-profile flight to deliver supplies to the international space station and to bring its first full-time crew back to Earth.

See our complete list of deorbit and landing times, which is up to date through Tuesday. We also have posted a detailed entry timeline and the latest weather forecast.

The Discovery astronauts will discuss the mission with reporters during a news conference beginning at 3:17 p.m. Entry flight director Leroy Cain will provide an updated forecast and the latest information on NASA's landing strategy during a 5:30 p.m. News conference. Detail from both briefings will be posted here later this afternoon.

FRIDAY, OCTOBER 20, 2000

The Discovery astronauts undocked from the international space station today, wrapping up a successful mission to ready the complex for delivery of a huge set of solar arrays in December and its main laboratory module in January. Spaceflight Now's William Harwood interviewed the astronauts a short time later. Read our full story, plus watch the interview.

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

The final separation burn of Discovery's thrusters has been performed and the shuttle is now quickly departing the vicinity of the international space station. The astronauts will shortly set up for some in-flight news interviews today include one with Spaceflight Now!

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

A two-foot-per-second out-of-plane separation burn has been performed using Discovery's thrusters to further move away from the space station.

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

Now 20 minutes since undocking. The distance between the two spacecraft is now 1,100 feet and growing at 1.6 feet per second.

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

Having reached a point 150 feet away from the space station, pilot Pam Melroy has performed a maneuver to send Discovery in a half-loop around the outpost. Unlike previous shuttle flights to the station, Discovery will not perform any complete flyarounds today.

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

In the first two minutes since undocking, Discovery has backed away from the station by some 50 feet.

1508 GMT (11:08 a.m. EDT)

UNDOCKING! "Physical separation, Houston," commander Brian Duffy just radioed as shuttle Discovery departs from the international space station after a week-long construction visit that added 10 tons to the outpost. The undocking is occurred high above Brazil a few seconds earlier than planned.

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

Once the hooks and latches holding the shuttle and station together are release, large springs with push the two craft apart. Pilot Pam Melory will then fire some of Discovery's jet thrusters to back the shuttle a couple hundred feet away from the station.

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

The joystick-like controller on the aft workstation of Discovery's flight deck has been activated. This controller will be used by pilot Pam Melroy as she flies the shuttle away from the station.

1504 GMT (11:04 a.m. EDT)

Clocks counting down the last five minutes before today's undocking.

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

Mission Control reports the leak check looks good and Discovery is cleared to undock as planned in just 12 minutes.

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

Lead Flight Director Chuck Shaw has polled his team of controllers and gave a final "go" for undocking at 11:09 a.m. EDT this morning pending completion of a leak check. Meanwhile, astronaut Bill McArthur has powered up Discovery's docking mechanism.

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

Now 30 minutes away from the scheduled time of undocking for space shuttle Discovery as it departs the international space station after a week-long visit. Russian flight controllers have given approval for the undocking and report the solar arrays on the station have been feathered to an edge-on position as a form of protection against the shuttle's thruster plumes.

Read our undocking preview story.

THURSDAY, OCTOBER 19, 2000
2020 GMT (04:20 p.m. EDT)

Running a few hours behind schedule, the Discovery astronauts have been given permission to leave the Unity module's internal hatches open overnight, giving the crew extra time to finish the space station's outfitting early Friday.

This will delay Discovery's undocking from the international outpost by one 92-minute orbit, from 9:40 a.m. Friday to around 11:12 a.m.

The astronauts, meanwhile, still plan to close hatches between Unity and the Russian Zarya module later today after work there is complete.

The crew fell behind schedule today for a variety of reasons, including work to fix the shuttle's balky toilet. A system used to automatically scrape layers of shredded solid waste off the toilet's bowl hung up, forcing Jeff Wisoff to complete the job manually.

"You don't actually have to go in, but it's not the most pleasant job in the world," said NASA spokesman James Hartsfield. "Wisoff apparently drew the maintenance duty for that."

The toilet work put the crew about a half-hour behind schedule. Work to check out the station's four massive control moment gyroscopes, housed in the newly installed Z1 truss, then turned out to be more time consuming that expected, throwing the astronauts further behind.

All four gyros were spun up to 100 rpm and all four performed as expected. But by 4:15 p.m., the crew's exit from the Zarya module was running about two hours behind schedule.

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

The crew has started proceedures to test the control moment gyros on the Z1 Truss. The devices will be spun up for a test and heaters will be activated. The gyros will not become fully operational until after the arrival of the U.S. laboratory module, Destiny.

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

Discovery pilot Pam Melroy is working inside a closet-sized compartment on the Z1 Truss to complete connections between the truss and the station. Other crew members continue to work at opening the hatches to the Zarya module.

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

The Russian and U.S. flight control teams have given the crew a "go" to enter the Zarya module.

1408 GMT (10:08 a.m. EDT)

The crew are inside the Unity module and are awaiting for a "go" from Mission Control to open the hatch to the Zarya module, also known as the FGB, after its Russian acronym.

1330 GMT (9:30 a.m. EDT)

Discovery's astronauts were awakened at 6:17 a.m. EDT to begin flight day nine of their mission. The crew will be working inside the International Space Station today. They will transfer supplies and equipment, and conduct a crucial test of the gyros on the newly installed Z1 Truss.

WEDNESDAY, OCTOBER 18, 2000
2157 GMT (5:57 p.m. EDT)

The fourth and final space station construction spacewalk of this shuttle mission is over. Spacewalkers Jeff Wisoff and Mike Lopez-Alegria began repressurizing Discovery's airlock at 5:56 p.m. EDT, signalling the end of the 6-hour, 56-minute excursion. The total duration for the four spacewalks of STS-92 is 27 hours and 19 minutes. Check back a little later for a wrap up story and pictures from the spacewalk.

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

The spacewalkers are putting away their tools and equipment in Discovery's payload bay before returning the airlock in less than an hour. NASA has opted to skip the incapacitated crew member maneuvering test due to the lack of time.

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

Mission Control is looking to see if there enough time left for the astronauts to perform the final activity today, which would be Jeff Wisoff and Mike Lopez-Alegria taking turns pretending to be incapacitated to practice techniques for manually hauling an injured spacewalker back to the safety of the shuttle's airlock.

2015 GMT (4:15 p.m. EDT)

Mike Lopez-Alegria has taken the amazing flight using the jetpack to fly from near the international space station to a point in the back of the shuttle's payload bay. The demonstrations appeared to go well.

1926 GMT (3:26 p.m. EDT)

Astronaut Jeff Wisoff has completed his turn flying the jet backpack. Now Mike Lopez-Alegria will take a try.

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

Testing of the SAFER backpacks has begun.

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

The two spacewalkers have set up their tethers in preparation to start the demonstration test of the Simplified Aid For EVA Rescue, or SAFER, jet backpacks.

With one astronaut anchored to the end of the shuttle's robot arm and playing out his partner's safety tether like a fishing line, the other will free fly 50 to 60 feet from the space station down to a camera mounted on the aft bulkhead of Discovery's cargo bay.

"Jeff will be the first to try this," Mike Lopez-Alegria explains. "First of all, we'll do some tether protocol so Jeff will always remain tethered. The SAFER guy will always remained tethered during the whole operation.

"But the eventual goal is, we're going to start him up on the stack, as we call it, to somewhere around the (Russian Zarya module). And he will aim toward the aft bulkhead, one of the cameras. And, basically, I will be tending him on the arm.

"At one point, I'll be in the arm, basically, in a foot restraint, holding him. And I'll back away. I'll let go of him. And he will orient himself using the hand controller and then try to actually fly as if he were doing a self-rescue."

Lopez-Alegria will trade places for a second test flight.

1800 GMT (2:00 p.m. EDT)

Today's spacewalk is now entering its third hour. The spacewalkers are running a bit behind schedule due to some tool troubles. Wisoff and Lopez-Alegria are still working on some space station assembly tasks before they move on to the test flight of the jet backpacks.

1720 GMT (1:20 p.m. EDT)

The spacewalkers have completed deployment of a large tray-like panel on the international space station's Z1 truss. The tray will hold power cables and ammonia coolant lines running between the U.S. solar arrays and Destiny laboratory module when they are added in the coming months. Mike Lopez-Alegria is finishing up working with some launch restraints on the tray.

Meanwhile, Jeff Wisoff has moved on to check the manual berthing mechanism capture system on the truss that will be used during installation of the Destiny laboratory module early next year.

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

Now 90 minutes into today's spacewalk. The next job of this excursion is to position a tray on the bottom of the Z1 truss where cables will be run to the U.S. Destiny science laboratory when it arrives at the station in January.

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

The releasable grapple fixture on the Z1 truss has been removed. The structure's deck is now completely cleared to make way for attachment of the solar array module in two months on the next space shuttle mission.

1551 GMT (11:51 a.m. EDT)

The spacewalkers have swiftly gotten to work today. Jeff Wisoff has completed the cycle test of the "claw" latch on the top of the Z1 truss, which will be used to captured and lock the U.S. solar array package into place in December. Mike Lopez-Alegria, meanwhile, is preparing to remove the robotic arm grapple fixture on Z1 truss since it is no longer needed.

1501 GMT (11:01 a.m. EDT)

The fourth and final spacewalk of this 100th space shuttle mission is now underway. Today's tasks for spacewalkers Jeff Wisoff and Mike Lopez-Alegria will include removing a grapple fixture from the Z1 truss, checking latches on the structure that will capture the U.S. solar array module when it arrives in December, deploy a tray that will be used to provide power to the U.S. Laboratory "Destiny" when it arrives in January and test docking mechanism latches that will support Destiny. The final task will be the test flight of jet backpacks. Read our spacewalk preview story.

TUESDAY, OCTOBER 17, 2000

Two spacewalkers installed a pair of transformer-like devices aboard the international space station today that will step down and regulate the voltage produced by a huge set of solar arrays scheduled for installation in December. Read our full story on today's spacewalk.

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

Today's spacewalk concluded at 5:18 p.m. EDT for a total duration of 6 hours and 48 minutes. That brings the total spacewalk time over three excursions during Discovery's mission to 20 hours and 23 minutes.

2015 GMT (4:15 p.m. EDT)

Spacewalker Leroy Chiao has bolted the Z1 keel pin to the structure's starboard side, completing the final task of today's excursion. Chiao and fellow spacewalker Bill McArthur will now clean up the payload bay, putting away tools, tethers and other equipment before returning to the shuttle's airlock over the course of the next hour.

1930 GMT (3:30 p.m. EDT)

Today's spacewalk now passing the five-hour mark in duration. Bill McArthur is nearly finished moving tools from a bag on Unity to a toolbox on the Z1 truss. Leroy Chiao, meanwhile, will soon relocate the keel pin that held the Z1 truss in Discovery's payload bay for launch. The pin will be removed from the bottom side of the truss and attached to the right side so it does not get in the way for future space station construction.

1912 GMT (3:12 p.m. EDT)

Relocating cables on the docking ports of the space station by spacewalker Leroy Chiao is wrapping up. Meanwhile, Bill McArthur is transferring tools from a bag attached to the station's Unity node exterior in May 1999 to the newly installed toolbox on the Z1 truss.

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

Now four hours into today's spacewalk. The spacewalkers are running about 15 minutes ahead of schedule, despite frequent pauses to enjoy the view from 240 miles up.

"What part of the world are we going to be flying over in daylight," McArthur asked as Discovery raced toward an orbital dawn over the south Pacific Ocean. "It looks like sunrise is right about over New Zealand," someone on Discovery's flight deck replied.

"Whoo!"

"Bill, I'm going to try to get some shots of you," Chiao said, looking down into the shuttle's cargo bay from his perch on the end of Discovery's robot arm. "I think I'll be able to get some good angles coming down."

"Yep. Shots of me just hanging around," McArthur joked.

"If I can get my camera out of this bayonet fitting..."

"Oh man, I apologize Leroy, I wish I hadn't run out of film."

"That's OK."

"Aw, it's spectacular! You just look so neat! Can you see the mother ship?"

"No."

"Oh good God, the orbiter's on its side! Everything's going to fall out!"

"Did you stow your camera Bill, when you went by the airlock?" Chiao asked. "I did."

"I'll tell you what, If you want I'll hand you this camera because it's a bit of nuisance, after I come down there. I'll take some good shots of you."

A few moments later, McArthur once again commented on the sight of the station's new antenna boom extending out into space.

"That dish does look pretty up there, doesn't it?"

"Yeah, that's a neat sight," Chiao agreed. "I hope those pictures turned out over Gibralter."

"Absolutely," McArthur said. "Well, Leroy, how would you like to live on this thing for a few months? I think that would be pretty cool."

"Pretty cool."

"It would be neat, yes it would be," McArthur sighed. "Livin' in space..."

1808 GMT (2:08 p.m. EDT)

A toolbox has been fitted the hull of the international space station, completing yet another task of this smooth spacewalk today. The toolbox will be used by future space station assembly crews. A similar box was mounted to the station during an earlier spacewalk on this shuttle mission.

Spacewalkers Leroy Chiao and Bill McArthur are now set to make the final power cable connections on both the Z1 truss and the station's new docking port installed yesterday. This re-routing of cables will direct power from the current shuttle docking port (Pressurized Mating Adapter 2) to the new PMA 3.

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

The health check of the two DC-to-DC converter units installed to the space station today has been completed successfully.

1740 GMT (1:40 p.m. EDT)

The next job for the spacewalkers today is transferring a toolbox from a pallet in Discovery's payload bay for installation to the space station's exterior.

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

An aliveness test is getting underway to verify the four umbilicals just connected from the Z1 truss to the space staion's Unity node are hooked up properly, routing power to the new DC-to-DC converter units.

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

As the final umbilical is attached by the spacewalkers, space station flight controllers report the heaters on the newly installed DC-to-DC converter units have been activated.

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

The second of two DC-to-DC converter units has been attached to the international space station's new Z1 truss by the spacewalkers. The units will regulate the voltage provided to the station from the U.S. solar arrays when they are added in December. The next task of today's excursion will be connecting some umbilicals on the truss.

1613 GMT (12:13 p.m. EDT)

The first of two DC-to-DC converter units - DDCUs - has been unbolted from a sidewall carrier plate in the shuttle Discovery's payload bay. Spacewalkers Leroy Chiao and William McArthur are preparing to mount it on the side of the Z1 truss.

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

There are no problems, after all, positioning the shuttle Discovery's robot arm. The problem spacewalker Leroy Chiao, attached to the end of the arm, was having earlier involved his adjustable foot restraint. After correcting its alignment, the crew pressed ahead with work to install two DDCUs on the Z1 truss.

1535 GMT (11:35 a.m. EDT)

Spacewalkers William McArthur and Leroy Chiao have completed setting up their tools and work platforms and are pressing ahead with work to install two 129-pound DC-to-DC Converter Units. The DDCUs, which will be mounted on the side of the newly installed Z1 truss, will step down and regulate power from the P6 solar arrays scheduled for attachment to the truss in early December.

For this procedure, Chiao is attached to the end of Discovery's robot arm. The arm is being operated this morning by Michael Lopez-Alegria. As of 11:35 a.m., Chiao and Lopez-Alegria were having a bit of a problem getting the arm properly positioned.

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

During work to break out tools and set up equipment for today's spacewalk, astronaut William McArthur noticed a cap that normally fits over the shuttle Discovery's airlock depressurization valve floating away into space.

"OK, I see the airlock cap floating away," he called. "Do you see it? The depress valve cap. ... It just bounced against Z1. I'll just kind of watch it for a moment... I don't think it's going to come back in this direction, but I'll just watch it."

Ellen Ochoa in mission control asked the astronauts to make sure the valve cap could not make its way into the structure of the newly attached Z1 truss. McArthur said there was no problem.

"It was a nice billiard shot," he said. "It caromed off the corner of Z1 and then off the arm and now it's become the latest addition to the tiny bodies orbiting the Earth."

The small cap apparently broke free of its tether attachment. It is redundant and its loss will have no impact on Discovery's mission.

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

The third of four spacewalks of this 100th shuttle flight is now underway. Astronauts Leroy Chiao and Bill McArthur have switched their spacesuits from shuttle-provided powered to internal batteries, signalling the official start of today's planned 6 1/2-hour space station construction spacewalk.

The two men will float outside the shuttle's airlock hatch in the next few minutes and start gathering tools and equipment for the excursion. The main goal of this spacewalk is to mount two DC-to-DC converter units, or DDCUS, on the space station's new Z1 truss installed on Saturday. Chiao and McArthur will also attach additional umbilicals and mount tools on the station's exterior for use by future assembly crews.

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

Discovery's astronauts plan to carry out the third spacewalk of their mission later today to ready the international space station for the attachment of a huge set of solar arrays in early December. Read our spacewalk preview.

MONDAY, OCTOBER 16, 2000
2129 GMT (5:29 p.m. EDT)

Mike Lopez-Alegria and Jeff Wisoff are repressurizing shuttle Discovery's airlock, which officially concludes today's 7-hour, 7-minute spacewalk. The EVA started at 10:15 a.m. and ended at 5:22 p.m. EDT.

This brings the total spacewalk time for Discovery's flight to 13 hours, 35 minutes over the course of two excursions. It is also the eight spacewalk dedicated to international space station construction bringing that total to 55 hours and 50 minutes. For the entire space shuttle program, it was the 52nd spacewalk for a total of 324 hours and 26 minutes.

2020 GMT (4:20 p.m. EDT)

The spacewalkers have completed wiring the new docking port added to the international space station today and are now beginning to clean up the payload bay. They will be putting away tools and equipment before returning to Discovery's airlock within the next hour. Today's spacewalk has already lasted over six hours.

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

The primary set of cables have been connected between the space station and new docking port installed today. Mission Control reports initial commanding tests through the cables was successful. The spacewalkers are now hooking up the backup cables before calling it a day.

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

Spacewalker Mike Lopez-Alegria is releasing the launch restraints bundling the power and data cables and Jeff Wisoff is moving into position to actually connect the wires from PMA 3 to the Node.

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

The spacewalkers are preparing for the final job of today's excursion: wiring up the new docking port to the rest of the space station. Mike Lopez-Alegria and Jeff Wisoff will connect cabling from the new Pressurized Mating Adapter 3 to the Unity module.

Meanwhile, NASA officials have asked the two men to bring two portable foot restraints used during spacewalks into Discovery's crew cabin today. The shuttle astronauts plan to perform some minor maintenance on the platforms and then return them to the exterior of the space station during Wednesday's spacewalk.

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

Now four hours into today's spacewalk.

1801 GMT (2:01 p.m. EDT)

The shuttle's robot arm has detacted from the Pressurized Mating Adapter 3. Operator Koichi Wakata is now backing the arm away the port. He is expected to maneuver spacewalker Jeff Wisoff on the end of the 50-foot arm during cable connections to wire the docking port to the rest of the station.

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

Discovery pilot Pam Melroy has completed today's efforts to tighten 16 electrically-driven bolts that join the new docking port to the Unity node. Further tightening will be performed tomorrow after the seals between the two station pieces can thermally stabilize.

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

The international space station has a new docking port for use by visiting space shuttles in the future. The Pressurized Mating Adapter 3 has been attached to the station's Unity module using Discovery's robot arm and visual assistance by the spacewalking astronauts. The new port will be used for the first time in December when the next shuttle arrives at the station. The port where Discovery is docked -- PMA 2 -- will become the attachment point for the U.S. Destiny Laboratory in January.

Shuttle pilot Pam Melroy will now -- via a lap-top computer-- command bolts and capture latches to close to firmly join the PMA and Unity. The spacewalkers have some other chores to do over the next little while before they connect some cables between the new PMA and Unity.

Today's spacewalk has lasted nearly 3-1/2 hours in duration.

1725 GMT (1:25 p.m. EDT)

Standing by for attachment of PMA 3 to the station in the next few minutes.

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

Spacewalker Mike Lopez-Alegria has completed relocating Circuit Interrupt Devices on the Z1 truss, which will serve as circuit breakers for the U.S. solar arrays when they are delivered to the international space station in December. Also, Jeff Wisoff has removed launch restraint caps and opened latches on the truss so the solar array truss can be attached by the crew of Endeavour on the next shuttle mission.

1655 GMT (12:55 p.m. EDT)

The PMA 3 has been maneuvered in its pre-installation position next the Unity node of the international space station. Once the spacewalkers complete some work they are doing on the Z1 truss of the station, they will head over to Unity to assist in helping the PMA by assisting arm operator Koichi Wakata on the alignment.

Mike Lopez-Alegria explains: "We're going to use sort of man-in-the-loop visual feedback, you know, like the guy in the garage that tells you to bring your car back. Kind of a guidance."

Wakata can't actually see the attachment (it is above the shuttle's crew cabin), so he is relying on the computer-driven Space Vision System and the spacewalkers' input.

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

Spacewalker Jeff Wisoff reports there is several feet of clearance between the PMA and Zarya's solar arrays, so the docking port is once again moving towards the Unity node for installation.

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

As Discovery and the international space station orbit in darkness, the astronauts inside the shuttle cannot clearly see the separation distance between the PMA -- on the end of the robot arm -- and one of the Zarya module's solar arrays. So spacewalker Jeff Wisoff is climbing up to give a first-hand view of the clearance before arm operator Koichi Wakata resumes maneuvering the PMA to its installation position on the Unity node above Discovery's nose.

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

Mission Control has told robot arm operator Koichi Wakata to maneuver to the PMA to the installation position and skip the so-called "high hover" holding pattern originally planned. This new plan will allow the massive docking port to shade the attachment mechanism on the space station sooner, which is currently warming up.

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

The Pressurized Mating Adapter 3 is now on its way from the launch support pallet in the shuttle's payload bay to attachment on the international space station. The PMA docking port is riding on the end of Discovery's robot arm.

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

The computer-driven Space Vision System has been powered up. It will be used extensively today as the PMA 3 docking port is mounted to the international space station above the shuttle's nose. The system uses a dedicated computer, targets painted on station components and cargo bay television cameras to geometrically determine a component's exact orientation and position with respect to the space station or the shuttle.

Meanwhile, the spacewalkers are now moving on to their next task. Mike Lopez-Alegria will be relocating two sets of Circuit Interrupt Devices, or CIDs, on the Z1 truss (installed to the station on Saturday), while Jeff Wisoff removes some launch restraint caps on the truss that are on four different attach points where the solar array truss will be mounted in December on the next shuttle mission.

1601 GMT (12:01 p.m. EDT)

The latches are open and the PMA 3 is now completely free to be lifted from Discovery's cargo bay using the 50-foot arm under the control of Japanese astronaut Koichi Wakata.

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

All the bolts have been released that held the Pressurized Mating Adapter 3 to its pallet in Discovery's cargo bay. Four restraint latches will soon be undone and the shuttle's robot arm shall maneuver the newest space station element for attachment to the Unity module.

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

The shuttle is now in so-called "free drift" where Discovery's jet thrusters are inhibited from firing. This is done while the final four bolts are released between the PMA docking port and its support platform.

1544 GMT (11:44 a.m. EDT)

Discovery's robot arm has now firmly grappled the PMA 3.

NASA reports the spacewalkers increased the torque rate on their drill-like tools used to release the PMA from its launch pallet in response to an earlier problem.

1539 GMT (11:39 a.m. EDT)

All 16 bolts holding the PMA to the platform in Discovery's payload bay have been loosened. Now the spacewalkers will completely release the bolts.

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

Discovery's 50-foot robot arm, under the control of astronaut Koichi Wakata, is now moving to grapple the PMA docking port resting in Discovery's payload bay. The arm will be used later today to hoist the port and mount it to the international space station.

Meanwhile, the spacewalkers are currently loosing the bolts holding the port to its launch pallet.

1514 GMT (11:14 a.m. EDT)

The trouble the spacewalkers are having is with the restraint latches holding the PMA. The original plan had called for the latches to be opened in a test before 16 bolts are released, which actually hold the docking port to its pallet. The latches would be re-engaged so that when the bolts are undone, the latches still hold the PMA. But now Mission Control has told the crew to skip the latch test and to press ahead with releasing the bolts.

Here is how spacewalker Mike Lopez-Alegria described the PMA release work in a NASA interview:

"There are 16 bolts that attach PMA-3 to the structure," he said. "First of all, Jeff will go up and cycle some latches that are not holding it in place - the bolts are - but will be used later as we release it to sort of constrain its motion. We'll cycle that and make sure it works OK.

"Then each of us will start releasing the torque on these 16 bolts, kind of opposite each other as we go, kind of like on a clock face. Once the torques have been released, we'll go back through and, using a Pistol Grip Tool - which is basically a very complicated, glorified, cordless screwdriver - we're going to continue to unbolt each of those bolts until the PMA is actually free."

1456 GMT (10:56 a.m. EDT)

In advance of today's installation of the new Pressurized Mating Adapter 3 docking port to the international space station, the Common Berthing Mechanism is being opened on the Unity node where the PMA will be attached. The new port will be mounted over shuttle Discovery's nose.

Meanwhile, the spacewalkers have experienced some difficulty with their drill-like tools used to release the PMA from its launch pallet.

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

The spacewalkers are quickly getting to work in Discovery's payload bay. This is Jeff Wisoff's second spacewalk and Mike Lopez-Alegria's first.

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

Astronauts Jeff Wisoff and Mike Lopez-Alegria switched their spacesuits from shuttle-provided powered to batteries at 10:15 a.m. EDT, signalling the official start of today's planned 6 1/2-hour space station construction spacewalk that will mount a new docking port to the outpost.

The airlock depressurization was delayed a few minutes today because a valve was not in the correct position.

Once the two float outside the airlock hatch in the next few minutes, they will spend nearly an hour getting acclimated and setting up tools and equipment before the spacewalk's first task: unlocking restraint bolts that are currently holding the so-called Pressurized Mating Adapter 3 to its pallet in Discovery's payload bay. With the bolts undone, Japanese astronaut Koichi Wakata will lift the PMA 3 with Discovery's robot arm for today's attachment to Unity module of the space station.

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

With one complex spacewalk successfully completed, the Discovery astronauts are gearing up to carry out a second excursion Monday to attach a new $20 million shuttle docking port to the international space station's Unity module. Read our full spacewalk preview story.

SUNDAY, OCTOBER 15, 2000
2102 GMT (5:02 p.m. EDT)

Today's spacewalk marked the seventh to assembly the international space station, bringing the total duration to 48 hours and 43 minutes. It was also the 51st spacewalk performed from a space shuttle for a grand total of 317 hours and 19 minutes. For the entire U.S. manned space program, this was the 90th spacewalk.

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

Leroy Chiao and Bill McArthur have begun repressurizing shuttle Discovery's airlock, which officially concludes today's six-hour, 28-minute spacewalk. The EVA started at 10:27 a.m. EDT when the spacewalkers switched their suits from shuttle-supplied power to internal batteries.

The two men successfully completed all their tasks, including wiring the new Z1 truss to the rest of the international space station, relocating the S-band antenna system on the truss, deploying the outpost's high-data rate Ku-band communications antenna and mounting a toolbox to the Z1 for use by future spacewalkers.

Attention now turns to tomorrow's spacewalk when astronauts Michael Lopez-Alegria and Jeff Wisoff venture outside the shuttle to assist in the installion of a new docking port to the international space station.

A total of four spacewalks are planned on this 100th space shuttle mission over the course of four consecutive days.

2027 GMT (4:27 p.m. EDT)

Today's spacewalk has now lasted six hours in duration. The spacewalkers are finishing their chores to put away tools, tethers and other equipment.

1941 GMT (3:41 p.m. EDT)

The final job on today's spacewalk -- mounting a toolbox to the side of the space station's Z1 truss -- has been completed. This spacewalk by astronauts Leroy Chiao and Bill McArthur has gone extremely well with no significant problems encountered. The duo will now clean up the payload bay, put away tools and equipment used today and return to the shuttle's airlock over the next hour.

1930 GMT (3:30 p.m. EDT)

The toolbox has been removed its launch platform in Discovery's payload bay and is currently being moved up to the Z1 truss of the station for attachment by the spacewalkers.

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

Today's spacewalk has now lasted 4 1/2 hours.

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

Now that the high-data rate Ku-band communications antenna is deployed on the international space station, the final task of today's spacewalk will be taking a toolbox from a pallet in Discovery's payload bay and relocate it to the Z1 truss.

Bill McArthur explains: "I go back up, get back on the arm, and our last primary task on that is for me to go to the back of this pallet, this bracket that's in the payload bay, which is holding Pressurized Mating Adapter No. 3, and I release a toolbox that's attached to it. Koichi brings me around and on the, you know, looking from the tail, on the right side of Z1, I'll then install this toolbox which contains tools that will be used both by us and by EVA crewmembers throughout the life of the station, both station crewmembers and subsequent shuttle crewmembers who come up and do assembly ops."

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

Using their hands, the spacewalkers have pulled the Ku-band boom from its stowed position against the side of the Z1 truss to its extended position. Two bolts will be added to keep the boom deployed.

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

The spacewalkers have bolted the Ku-band antenna to its deployable boom on the Z1 truss of the international space station. Also, the gimbal restraint bolts that held the dish in place have been removed. Now a couple of cables will be connected to the antenna before the boom is extended.

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

The 78-inch diameter Ku-band dish has been removed from its launch restraint on the Z1 truss in advance of attaching the 190-pound antenna to its boom.

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

The spacewalkers have finished connecting the second string of umbilicals between the new Z1 truss to the international space station's Unity node. This string is basically a bundle of four power cables.

McArthur explains what's still ahead today: "Now, the next task will be to release another communications antenna, the Space-to-Ground Antenna - and we call it SGANT, but it's Space-to-Ground Antenna - and it's in the K-band system. It would only communicate through the TDRS or Tracking and Data Satellites - and this one really looks like an antenna. It's a large parabolic dish, somewhat fragile. Okay, so it makes us a little bit nervous.

"Anyhow ... we'll release this antenna. And then I have this T-bar that comes out of the base of the antenna, and I'm sort of holding it off to the side. And then Koichi will move me aft in the payload bay; Leroy will be guiding the antenna as well, and will guide it clear of the Z1 structure itself.

"Leroy then moves over to the left side of Z1 - left side as you're facing forward - and positions himself near this boom that's folded down on that face of Z1. So, Koichi will move me over on the end of the arm. I'll rotate the antenna around, present it to Leroy, and then Leroy will begin bolting it to this boom. I have to, at that point, get off the arm, crawl along Z1, around underneath the antenna, to attach one of the bolts and a couple of electrical connectors that provide power and data to the antenna.

"Once that's all said and done, Leroy moves around to sort of the topside of the boom. And then we, by hand, we just fold the boom out. And once the boom's folded out, Leroy's got a couple of bolts that he attaches to the base to hold it in position. And then the K-band system is simply waiting to be activated on Flight 6A."

1710 GMT (1:10 p.m. EDT)

Nearing three hours into today's spacewalk. Mission Control reports that astronauts Leroy Chiao and Bill McArthur are running around 20 minutes ahead of the timeline. The spacewalk -- the first of four planned on this shuttle mission -- has been going smoothly without any difficulty.

1655 GMT (12:55 p.m. EDT)

Spacewalker Bill McArthur explains what the next job will be: "Once the electrical reconfiguration is complete, Koichi will stick me back down underneath the Z1 and I'll then release the next set of four cables and attach them to the Node. And then we'll be ready for pretty nominal power status onboard the space station."

1642 GMT (12:42 p.m. EDT)

Flight controllers report the first six cables that were attached from the Z1 truss to the international space station appear to have been connected properly. The spacewalkers next task is connecting another string between the truss and station -- this one with four cables.

1627 GMT (12:27 p.m. EDT)

The spacewalkers have completed installing the S-band antenna to its new position on the Z1 truss, and attached two umbilical lines that will provide operational and heater power to the communications assembly.

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

Eight bolts have been released and the spacewalkers are now removing the S-band Antenna Subassembly from its launch location the Z1 truss. They are moving it to another position on the truss because two DC-to-DC power converter units will be installed into the S-band's original slot on the girder-like Z1 structure during another spacewalk on Tuesday.

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

With the first umbilicals attached from Z1 to Unity, verification the connections are beginning. Meanwhile, spacewalkers Bill McArthur and Leroy Chiao are now moving on to the next job: relocating the S-band antenna on the Z1 truss.

McArthur explains: "Koichi is going to move me up into position by a device called the S-band Antenna Support Assembly. Then Leroy and I will get in position. I'm on the arm. Leroy will be in another foot restraint fixed to the side of Z1. And we're working now on the side of Z1, which is on the left side of the payload bay of the space shuttle. And so, we have to release a series of bolts. And we'll do that with these electrical wrenches - and we call them Pistol Grip Tools; they look like, you know, very sophisticated electric screwdrivers - and we'll release a series of bolts and electrical connectors that will free up this large S-band antenna assembly.

"Then Koichi will pull me away from Z1. I will rotate the S-band antenna 180 degrees so it points toward the Node. And then Koichi will move me over in position. We'll put it in a temporary location, and, while Leroy holds it, I'll bolt it back down. And this is a temporary location because it will not actually be put into its final or its first usable location and activated until the next flight (shuttle Endeavour's mission in December)."

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

Spacewalker Bill McArthur, serving as an high-flying electrican, has connected six cables between the Unity node of the international space station and the Z1 truss structure attached to the outpost yesterday. The cables will provide electricity from the Node to the truss, electrically connect Z1 to the Russian Zarya module, give voltage and current stablization from the future U.S. solar arrays (to be launched in December) to the Russian Zvezda module and route guidance and control data from the truss to ground controllers.

1531 GMT (11:31 a.m. EDT)

NASA officials report one of the Russian-to-American Conversion Unit No. 5 has been powered off aboard the international space station. The RACUs provide power to some of the systems in the Unity module including the early communication system and cabin fans. This powering down is important because it ensures there isn't any electricity in the connections that the spacewalkers will attach six cables from the Z1 truss.

Later today the RACU No. 5 will be turned back on and then No. 6 will power down when four other cables are connected -- thus Unity is never without power.

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

The official start time of today's spacewalk has been revised to 10:27 a.m. EDT.

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

Bill McArthur has installed the so-called Adjustable Portable Foot Restraint to the end of the shuttle's robot arm. The small platform allows the spacewalker to clip his boots into this bracket to stand while ride the arm and be positioned at work areas by arm operator Koichi Wakata.

McArthur will soon be maneuvered to a spot underneath the Z1 truss so he can release the first six cables from their temporary location on structure for attachment to the Unity node of the station -- the first of several tasks planned for today's spacewalk.

1458 GMT (10:58 a.m. EDT)

Riding on the end of the shuttle's robot arm, an excited first-time spacewalker Bill McArthur has traveled to the top of the Unity node of the space station to retrieve a foot restraint left by a previous shuttle crew. McArthur has sounded very enthusiastic during the first minutes of today's station construction spacewalk. Meanwhile, veteran spacewalker Leroy Chiao is in Discovery's payload bay gathering tools.

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

The spacewalker are now floating out of Discovery's airlock. Leroy Chiao, designated EV1, is recognizable by the red bands on the legs of his space suit, and Bill McArthur, designated EV2, has a solid white suit.

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

Astronauts Leroy Chiao and Bill McArthur have switched their spacesuits from shuttle-provided powered to batteries, signalling the official start of today's planned 6 1/2-hour space station construction spacewalk.

Once the two float outside the airlock hatch in the next few minutes, they will spend nearly an hour getting acclimated and setting up tools and equipment before the spacewalk's first task: stringing a set of six electrical cables between the space station and the new Z1 truss installed yesterday.

1411 GMT (10:11 a.m. EDT)

The airlock aboard shuttle Discovery is now being depressurized in preparation for today's spacewalk.

1330 GMT (9:30 a.m. EDT)

Discovery astronauts Leroy Chiao and Bill McArthur are suited up and about one hour from beginning the first of four space station construction spacewalks during this shuttle mission. Today's 6 1/2-hour spacewalk will see the two men connect electrical cables between the Z1 truss structure and the station's Unity node. They will also relocated to communications antennas on the Z1 and add a toolbox to the truss.

Read a preview story of today's spacewalk.

SATURDAY, OCTOBER 14, 2000
2250 GMT (6:50 p.m. EDT)

After completing some work inside the pressurized vestibule between the Z1 truss and Unity node, the astronauts have closed up that area and are now exiting the space station for tonight. They are closing the hatches behind them in preparation of four consecutive days of spacewalks that begins tomorrow morning.

Because of the electrical short and delay of work this morning, NASA officials told the crew to forego entering the Zarya module of the station today. They had planned to transfer some equipment into the module for use by the first long-duration station residents this fall. But those supplies will now be moved on Flight Day 9 when the astronauts reenter the station after the spacewalks are completed.

At today's daily mission status news conference, Chuck Shaw, NASA's Lead Flight Director for the STS-92 mission, had this to say:

"Today was a very successful day. We had to struggle a little bit but we showed the reason manned spaceflight has been as successful as it has been for the large number of years. A large team of people scattered across the entire planet were able to all together to get a major advance in the space station assembly operations."

Discovery's astronauts are scheduled to begin an 8-hour sleep period at 10:17 p.m. EDT.

1910 GMT (3:10 p.m. EDT)

The sixteen bolts connecting the Z1 truss and international space station have been torqued to 19,300 pounds of force each. The truss is now a permanent piece of the outpost.

Later this afternoon the astronauts plan to open the hatch to a small vestibule between the Unity node and Z1 to connect electrical ground straps in the new truss structure.

1906 GMT (3:06 p.m. EDT)

Discovery's robot arm has let go of the Z1 truss now that it is attached to the space station. Meanwhile, the tightening of 16 bolts that hold the truss to the station's hull is nearing completion.

1835 GMT (2:35 p.m. EDT)

The sixteen bolts -- in sets of four -- are being driven remotely to bond the Unity node and new Z1 truss together. Also, Discovery's robot arm is now preparing to release from the truss' grapple fixture.

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

The girder-like Z1 truss structure has been connected to the international space station, providing the framework for continued construction of the orbiting outpost. The $273 million, 18,400-pound truss carries four stabilizing gyroscopes and the station's main S-band and Ku-band communications antennas. It will also act as the base support for the station's first solar array module due to arrive later this year.

Sixteen electrically-driven bolts will now torqued to permanently attach the truss to the station's Unity node. Initial capture was accomplished by the Common Berthing Mechanism docking port on the U.S.-made node. The CBM is a complex set of interlocking motor-driven petals and latches that firmly seal space station modules together. It was used for the first time today with the delivery of Z1.

1808 GMT (2:08 p.m. EDT)

Discovery's robot arm now maneuvering the Z1 truss the final inches toward the international space station.

1802 GMT (2:02 p.m. EDT)

Mission Control has told the crew they can begin moving the Z1 truss to its attachment to space station.

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

The Z1 truss has been maneuvered into position just a short distance away from the docking port on the international space station's Unity node. The astronauts and Mission Control are wrapping up the calibration of the Space Vision System.

1725 GMT (1:25 p.m. EDT)

The Space Vision System calibration continues.

1649 GMT (12:49 p.m. EDT)

Discovery's robotic arm has now hoisted the Z1 truss to the so-called "high hover position" over the left-side of the payload bay so a calibration test can be performed using the computer-driven Space Vision System. The system will be used to guide the truss to its attachment with the Unity node of the international space station this afternoon because arm operator Koichi Wakata does not have a clear view of the docking mechanism.

The Canadian-built system uses television cameras, a computer and targets on the station and components like the Z1 to determine the precise orientation and position of a component on the end of the robot arm.

It is critical for the Z1 installation "because we do not have a very good direct view through the window or from any camera views, I cannot see the connecting point of the Z1 and the Unity module very well," Wakata said before the flight. "So I have to depend on the ... Space Vision System."

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

Reactivation of the Common Berthing Mechanism on Unity appears to be sucessful. The CBM is basically the docking port for the Z1 truss to the international space station. Flight controllers are not sure what caused the mechanism to deactivate itself a short time ago and analysis is now underway.

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

Space station flight controllers just reported the Common Berthing Mechanism on the Unity node has deactivated itself. It is this device where the Z1 truss structure will mounted today. Engineers are looking at the situation. Meanwhile, astronaut Koichi Wakata is still slowly lifting the truss out of Discovery's payload bay using the shuttle's robotic arm.

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

The five latches holding the Z1 truss into Discovery's payload bay have been opened and astronaut Koichi Wakata is now raising the structure on the end of the shuttle's robot arm.

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

GRAPPLE. Discovery's 50-foot robot arm is now firmly attached to the grapple fixture on the Z1 truss. The arm will shortly lift the nine-ton truss out of the shuttle's payload bay and then mount it to the Unity node of the international space station. Meanwhile, the so-called Common Berthing Mechanism on Unity -- where the Z1 will be mounted -- has been opened to accept the truss attachment.

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

Japanese astronaut Koichi Wakata is now preparing to grapple the Z1 space station truss with Discovery's robot arm -- an opeartion delay about two hours this morning due to an electrical short circuit. The crew has restored the Space Vision System and will put astronaut Michael Lopez-Alegria inside the Unity node for visual cues to aid Wakata in maneuvering the 18,400-pound truss.

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

Efforts to restore the Space Vision System aboard shuttle Discovery have been successful and mission officials have told the astronauts to resume preparations to mount the Z1 truss to the international space station. The timeline has been delayed about two hours and 20 minutes today because of the electrical short that took out the Space Vision System, video cameras and some other hardware.

1412 GMT (10:12 a.m. EDT)

Flight director Chuck Shaw, taking the unusual step of talking to the Discovery astronauts directly, told commander Brian Duffy work to install the Z1 truss on the international space station will be held up pending additional analysis of a short circuit aboard the shuttle.

The 14-amp short circuit on payload bus No. 3 occurred at 8:57 a.m. as the astronauts were gearing up to unberth the Z1 truss from its mounting position in the back of Discovery's cargo bay.

The short took down the shuttle's upward-facing payload bay keel camera; an orbiter interface unit, or OIU, which allows the shuttle to talk to space station systems; and the Canadian-built Orbiter Space Vision System, a computerized television system needed to properly position the truss for attachment to the space station.

At 10 a.m., the crew was told to begin assembling tools to remove the space vision system's electronics unit so it can be powered from a different payload bus. The space vision system is critical, because arm operator Koichi Wakata cannot directly see the truss-station docking interface.

Shaw told Duffy he was confident the crew could berth the Z1 truss even without the space vision system and that the team would proceed in that fashion if necessary. But first, he wanted the crew to press ahead with work to re-wire the unit to an alternate power source.

In addition, astronaut Michael Lopez-Alegria will be positioned in the Unity module of the space station to give Wakata verbal cues as to the precise alignment of the truss with respect to the station's common berthing mechanism.

"We're going to go off and verify we've got enough cabling and power source options," Shaw told Duffy. "That's where we're heading right now and if you're comfortable with LA being back in the node doing that, I think that's the way we'll end up pressing on, we'll just up the gain on that cue."

"OK, Chuck, I think that sounds like a great plan," Duffy replied. "I know how hard you guys are working it and we'll be ready to go and follow your directions."

"Copy that," said Shaw. "This is a good sim."

"Unbelieveable is a little more like it."

--By William Harwood

1340 GMT (9:40 a.m. EDT)

An electrical short has halted activities aboard space shuttle Discovery this morning. The 14-amp electrical spike has knocked a critical payload circuit out of action and along with it, a Canadian computerized television system needed to install a major space station component. Read our full story.

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

Discovery's astronauts are already hard at work this morning as they prepare to attach a new section to the infant international space station. Japanese astronaut Koichi Wakata has powered up the shuttle's 50-foot robot arm that will be used to lift the Z1 truss structure from Discovery's payload bay and mount the nine-ton box to the station's U.S.-made Unity connect node. Read our full preview story of what will be happening today in space.

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

It is construction day in space as the astronauts of shuttle Discovery plan to mount an 18,400-pound truss structure onto the international space station. The so-called Z1 truss houses four stabilizing gyroscopes and critical electronic gear for the outpost.

Operating the shuttle's 50-foot-long robot arm, Japanese astronaut Koichi Wakata is charged with moving the boxy Z1 truss from Discovery's cargo bay to the top, or zenith, port of the U.S. Unity node, one of the three modules currently making up the space station.

The Z1 truss houses four large gyroscopes that will be used to keep the station stable and to change its orientation from time to time without having to burn limited on-board supplies of rocket fuel. It also features the station's main communications antenna and will serve as the temporary attachment point for a huge set of power-producing solar arrays slated for delivery in December.

The action will get underway at 8:47 a.m. EDT when the shuttle's 50-foot robotic arm is powered up. Wakata will then grapple the Z1 truss with the arm at 9:32 a.m. EDT. The truss is due to be attached to Unity at 12:27 p.m. EDT.

We will continuous updates on this page throughout the day.

FRIDAY, OCTOBER 13, 2000
2350 GMT (7:50 p.m. EDT)

Discovery's astronauts floated into the U.S. Unity module of the international space station station, beginning the transfer equipment and supplies from the shuttle to the orbiting outpost.

Meanwhile, NASA officials have decided against any further attempts to fix Discovery's broken Ku-band television and rendezvous radar system. The failure means live video from the shuttle will be available only through a few ground station passes last a couple of minutes in length. A sequential still video system, providing a still image updated every few seconds, is still operating.

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

The crew of space shuttle Discovery has entered the international space station. Mission Control reported the astronauts had opened the hatch to enter the station's docking port by 4:30 p.m. EDT, and then gave the crew the "go" to proceed into the U.S. Unity module. The station ingress timeline is running about 45 minutes behind schedule.

1808 GMT (2:08 p.m. EDT)

The shuttle astronauts have powered down Discovery's docking mechanism following today's successful linkup. Also, Russian mission controllers say the power-generating solar arrays on the Zarya and Zvezda modules are now tracking the sun again. They were locked to an edge-on position earlier today to protect them from Discovery's thruster plumes during final approach.

1759 GMT (1:59 p.m. EDT)

The extension ring on the shuttle's docking system has been retracted, bringing the international space station's docking port to a firm seal with Discovery. Hooks and latches also have now driven closed to keep the two craft joined.

Read our full docking story.

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

Discovery's docking ring, in which the space station is attached, now being retracted to firmly join the two craft together.

1746 GMT (1:46 p.m. EDT)

Mission Control reports the docking occurred at 1:45:15 p.m. EDT some 240 miles above Ukraine. Currently, the rates between the shuttle and station are being damped out. Later the docking ring on Discovery will be retracted.

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

CONTACT AND CAPTURE! Space shuttle Discovery has docked to the international space station for the fifth American visit to the orbiting outpost. The shuttle and its crew of seven will spend the next week attaching two new sections to the station and carrying out four consecutive days of spacewalks.

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

Discovery now just 10 feet away from the international space station's docking port.

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

Russian flight controllers report they have acquired the space station's signal.

1741 GMT (1:41 p.m. EDT)

Now 20 feet to docking.

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

Pilot Pam Melroy reports the docking alignment is acceptable and commander Brian Duffy won't need to perform a fly-out maneuver to correct any misalignment. Also, Mission Control has given the final "go" for docking -- now 7 minutes away.

A stationkeeping maneuver at 30 feet was not necessary. The brief hold would have been used to ensure proper timing so the docking occurs while in range of Russian ground stations. But that timing has all worked out today without the extra stationkeeping.

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

Inside 40 feet.

1728 GMT (1:28 p.m. EDT)

Just over 50 feet left to go before docking.

1724 GMT (1:24 p.m. EDT)

Now about 70 feet separating the shuttle and space station. Discovery is headed to a point 30 feet away where another stationkeeping position will be reached.

1720 GMT (1:20 p.m. EDT)

Discovery nearing a point 100 feet from the station's docking port, and closing at a rate of 0.16-feet per second.

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

Time to docking is now 30 minutes. Discovery and the international space station are currently flying above South America headed for docking over Central Asia while in communications range of Russian ground stations.

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

Discovery is once again moving towards the space station after stationkeeping at a distance of 170 feet above the outpost. Also, the astronauts have powered up the shuttle's docking mechanism.

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

Lead Flight Director Chuck Shaw has polled his team in Mission Control and given the astronauts a "go" to resume the approach to the international space station on-time in about 7 minutes.

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

Now one hour until docking of Discovery to the international space station. The shuttle continues its stationkeeping about 170 feet directly above station. Resumption of Discovery's trek to the station is due in about a half-hour.

1621 GMT (12:21 p.m. EDT)

Discovery has halted its approach to the international space station as planned, stopping at a distance of 170 feet from the docking port on the outpost's Unity node. The holding pattern will last about 50 minutes while the two orbiting spacecraft travel into the coverage zone of Russian ground stations. Docking still expected at 1:46 p.m. EDT.

1619 GMT (12:19 p.m. EDT)

Russian flight controllers report the solar arrays on the Zarya and Zvezda modules have been feathered -- or turned edge on -- to protect them from the plumes by Discovery's jet thrusters during final approach.

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

Discovery has reached a point directly above the international space station at a distance of under 250 feet. Commander Brian Duffy is now nudging Discovery toward the station's docking port, but will hold once the two craft are 170 feet apart until they pass within range of Russian ground stations.

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

Discovery is now about 600 feet directly below the international space station, closing at just over 1 mile per hour. Today's rendezvous is reported to be going as planned for docking at 1:46 p.m. EDT (1746 GMT). The shuttle is currently headed in a loop that will take it directly in front of the outpost in about 15 minutes and continue on to a point 250 feet above the station at 12:04 p.m., aligning the docking ports on both craft.

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

The international space station is now reported to be in the proper attitude for today's docking at 1:46 p.m. EDT (1746 GMT). Discovery is currently 7,000 feet behind and below the station, closing at a rate of 6 miles per hour.

1443 GMT (10:43 a.m. EDT)

Discovery is currently 37,000 feet behind and below the international space station, closing in at a rate of about 9 miles per hour. That closing rate will gradually be reduced just a tenth-of-a-foot per second at docking now three hours away.

In other news, mission managers today decided the shuttle astronauts would not enter the Zvezda service module of the station later on this flight. That decision, however, could be reverse if another battery problem hits the Russian module while Discovery remains docked to the station.

Officials had debated whether the crew should attempt an inspection on the module's battery system, which has suffered two battery failures since the most recent shuttle mission last month. The module -- which serves as the initial living quarters for the station -- has eight batteries and needs five to permit the first full-time crew to arrive in November.

The astronauts are not trained to service Zvezda's batteries and there was little they could do beyond inspecting connectors to make sure there are no obvious wiring problems.

1410 GMT (10:10 a.m. EDT)

Space shuttle Discovery has begun the final trek towards docking with the international space station following a 16-second firing of the left orbital maneuvering system engine. The so-called Terminal Initiation burn puts Discovery on course for docking at 1:46 p.m. EDT (1746 GMT).

The shuttle is currently 9 miles behind the station, but should arrive at a point 600 feet below the outpost at about 11:39 a.m. EDT (1539 GMT).

Read our full docking preview story.

0240 GMT (10:40 p.m. EDT)

Discovery's seven astronauts have gone to bed after their first full day in space -- a day when the shuttle's main TV relay antenna malfunctioned and threatens to cut virtually all live video from this 11-day mission. The crew will be awakened at 5:17 a.m. EDT (0917 GMT) for docking day as the shuttle completes its two-day orbital chase to rendezvous and link up with the international space station.

Thursday's activities in space were highlighted by the testing of equipment and tools to be used during the docking. The crew also prepared for the four consecutive days of spacewalks due to begin Sunday by checking over the spacesuits. Also, mission specialist Koichi Wakata powered up Discovery's the 50-foot robotic arm that will be used to attach the new pieces of the station carried aloft by Discovery and to move the spacewalkers around.

The mission -- from a public standpoint -- hit a disappointing setback with the Discovery's Ku-band antenna system used to downlink live television from the shuttle suddenly stopped working at about 10 a.m. EDT. The high-data rate system had worked properly in the first hours of the mission.

Engineers at Mission Control continue to analyze data in hopes of understanding the problem, potentially allowing the Ku-band system to be restored. However, that remains to be seen.

For now, the only video from Discovery will be when the shuttle passes over a couple of select ground stations in the U.S., allowing a few minutes of television. In the mean time, the sequential still imagery system will be used to provide views -- refreshed every 10 seconds -- through the shuttle's S-band communications system.

Once the astronauts are awakened Friday morning, they will step through their post-sleep time including breakfast and other personal activities. The rendezvous timeline begins at 7:32 a.m. EDT and the final phase of the sequence starts at 10:09 a.m. EDT with the Terminal Initiation burn. Docking is scheduled for 1:46 p.m. EDT -- marking the fifth U.S. visit to the international space station. See our docking timeline for a complete listing of Friday's events.

We will provide continuous live updates during Discovery's approach and docking to the station!

THURSDAY, OCTOBER 12, 2000
1630 GMT (12:30 p.m. EDT)

The shuttle Discovery closed in on the international space station today for a docking Friday amid troubleshooting to fix a potentially serious problem with the shuttle's main television antenna. Read our full story.

0645 GMT (2:45 a.m. EDT)

The Discovery astronauts have downlinked dramatic video recorded from inside the cockpit of the space shuttle, showing the jerking and shaking of launch and a surprising light show produced by the ship's main engine exhaust plume as the spacecraft left the atmosphere. Read our story that also includes images and video.

0110 GMT (9:10 p.m. EDT)

Discovery's astronauts have deployed the shuttle's Ku-band antenna used relaying television to Earth and for radar during docking and undocking with the international space station.

0055 GMT (8:55 p.m. EDT)

Space shuttle Discovery's two 60-foot-long payload bay doors have been swung open and Mission Control has given the "go" for on-orbit operations. Discovery is on track to rendezvous and dock with the international space station on Friday at 1:43 p.m. EDT (1743 GMT).

0017 GMT (8:17 p.m. EDT)

Now one hour since launch. Read our full launch story.

0001 GMT (8:01 p.m. EDT)

T+plus 44 minutes. Discovery's twin orbital maneuvering system engines have been fired to boost the shuttle from its suborbital trajectory to a near-circular orbit. Prior to the burn, Discovery was in a 201 by 46 mile orbit.

WEDNESDAY, OCTOBER 11, 2000
2356 GMT (7:56 p.m. EDT)

T+plus 39 minutes. A Spaceflight Now reader on Long Island in New York reports he saw Discovery's engine cutoff as the shuttle reached orbit tonight.

2349 GMT (7:49 p.m. EDT)

T+plus 32 minutes. The official launch time was 7:17:00.067 EDT.

2344 GMT (7:44 p.m. EDT)

T+plus 27 minutes. All three of Discovery's Auxiliary Power Units have been shut down since they are no longer needed tonight. One unit will be restarted on the day prior to landing for the aerosurface movement test, and all three APUs will be running for the shuttle's entry and landing 11 days from now.

2327 GMT (7:27 p.m. EDT)

T+plus 10 minutes. Discovery's ascent appeared very clean tonight with no problems reported during the thunderous journey into the Florida evening sky. Tracking cameras followed the shuttle for seven minutes as the shuttle streaked northeastward over the Atlantic Ocean.

2326 GMT (7:26 p.m. EDT)

T+plus 9 minutes. Confirmation of external fuel tank jettison.

2325 GMT (7:25 p.m. EDT)

T+plus 8 minutes, 30 seconds. MECO! Discovery's main engines have cutoff as planned, completing the powered phase of the launch. Space shuttle Discovery is now in orbit for its two-day chase to rendezvous and dock with the international space station.

2324 GMT (7:24 p.m. EDT)

T+plus 7 minutes, 40 seconds. Discovery' three main engines are throttling down to ease the ship's acceleration as it approaches loads to 3gs.

2324 GMT (7:24 p.m. EDT)

T+plus 7 minutes. The shuttle could make it to a safe orbit should two main engines fail.

2323 GMT (7:23 p.m. EDT)

T+plus 6 minutes, 15 seconds. Discovery now rolling to a heads-up position to provide better communications link with orbiting TDRS satellite system.

2323 GMT (7:23 p.m. EDT)

T+plus 6 minutes. About 2 1/2 minutes left in the powered phase of flight. All systems performing as expected.

2322 GMT (7:22 p.m. EDT)

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

2321 GMT (7:21 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.

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

T+plus 3 minutes, 30 seconds. Discovery's systems continue to perform normally with no problems reported so far in tonight's launch.

2319 GMT (7:19 p.m. EDT)

T+plus 2 minutes, 30 seconds. The twin solid rocket boosters have done their job and separated from the space shuttle Discovery moments ago after an incredible sunset blastoff.

2317 GMT (7:17 p.m. EDT)

LIFTOFF. Liftoff of the 100th space shuttle mission as Discovery clears the tower.

2316 GMT (7:16 p.m. EDT)

T-minus 31 seconds. Auto sequence start. Discovery's onboard computers are now controlling 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.

2316 GMT (7:16 p.m. EDT)

T-minus 1 minute. Computers verifying that the main engines are ready. 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 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; Discovery will transition to internal power and the liquid oxygen and liquid hydrogen outboard fill and drain valves will be closed.

2314 GMT (7:14 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 Discovery'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 Pam Melroy has been asked to clear the caution and warning memory system aboard Discovery.

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.

2313 GMT (7:13 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 this morning.

2313 GMT (7:13 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 Discovery 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.

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

T-minus 5 minutes. Go for Auxiliary Power Unit start. Pilot Pam Melroy is now flipping three switches in Discovery's cockpit to start each of the three APU's. The units, located in the aft compartment of Discovery, 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 Brian Duffy, 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.

2311 GMT (7:11 p.m. EDT)

T-minus 5 minutes, 25 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.

2311 GMT (7:11 p.m. EDT)

T-minus 6 minutes. Pilot Pam Melroy has been asked by Orbiter Test Conductor Roberta Wyrick to pre-start the orbiter Auxiliary Power Units. This procedure readies the three APU's for their activation at T-minus 5 minutes.

2309 GMT (7:09 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 Discovery 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.

2309 GMT (7:09 p.m. EDT)

T-minus 8 minutes and counting. Pilot Pam Melroy has flipped the switches in the cockpit of Discovery 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.

The launch of STS-92 will mark the 100th flight in the space shuttle program since 1981, the 75th since return-to-flight after Challenger, the 28th for Discovery and the fourth shuttle flight of 2000.

2308 GMT (7:08 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 Discovery at 7:17 p.m. EDT.

2307 GMT (7:07 p.m. EDT)

Now 10 minutes from launch.

2305 GMT (7:05 p.m. EDT)

The final management poll has been completed by Launch Director Mike Leinbach. All systems are go for launch and the weather is GO, clearing the way for the countdown to be restarted at 7:08 p.m. EDT for liftoff on-time today at 7:17 p.m. EDT to begin an 11-day mission to continue construction of the international space station.

"All good things are worth waiting for," Leinbach told Discovery commander Brian Duffy.

Once the countdown picks up, the Ground Launch Sequencer will be initiated. The master computer program is located in a console in Firing Room 3 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 Discovery to complete their own automatic sequence of events through the final half minute of the countdown.

2303 GMT (7:03 p.m. EDT)

The final readiness poll by NASA Test Director Steve Altemus has been completed with all parties "go" for launch. Mission Control also has given its "go" which indictates weather at the abort landing sites will not be a factor against launch today.

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

In the next couple of minutes the final readiness polls of the launch team and senior managers will be conducted before the countdown is allowed to resume at T-minus 9 minutes.

2255 GMT (6:55 p.m. EDT)

The latest weather forecast indicates all conditions currently acceptable and predicted remain that way for liftoff on time at 7:17 p.m. EDT today.

2247 GMT (6:47 p.m. EDT)

Now 30 minutes away from Discovery's sunset launch this evening from Kennedy Space Center in Florida to begin the 5th U.S. voyage to the international space station. At the time of launch, the orbiting outpost will be flying over the Indian Ocean at 12.18 degrees south and 84.49 degrees east.

After an 8 1/2-minute climb to orbit, Discovery should achieve an elliptical orbit with a high point of 194 miles and low point of 46 miles, Mission Control reports. A later firing of the twin orbital maneuvering system engines on the tail of Discovery will raise the orbit to 201 by 197 miles as the shuttles chases to catch the space station. Docking is planned on Friday at 1:43 p.m. EDT.

2240 GMT (6:40 p.m. EDT)

As a result of revised launch time tonight, this hold at T-minus 9 minutes is now scheduled to conclude at 7:08:00 p.m. EDT (2308:00 GMT) for a told hold duration of 36 minutes.

2236 GMT (6:36 p.m. EDT)

The final update to today's launch window has been announced based upon the final radar tracking of the international space station's orbit. The window extends from 7:13:16 to 7:21:12 p.m. EDT. The preferred launch time, which officials have now elected to shoot for, is 7:17:00 p.m. EDT. As a result of giving up the first four minutes or so of the window, NASA will have from 7:17:00 to 7:21:12 p.m. to get Discovery off the ground tonight -- a duration of four minutes and 12 seconds.

2232 GMT (6:32 p.m. EDT)

T-minus 9 minutes and holding. Countdown clocks have gone into the planned 36-minute built-in hold.

2231 GMT (6:31 p.m. EDT)

Flow of conditioned air into Discovery's payload bay has been reduced to 18 0 pounds per minute. Standing by to enter the T-minus 9 minute in one minute.

2230 GMT (6:30 p.m. EDT)

Results of the dump from the onboard computers is reported good.

2229 GMT (6:29 p.m. EDT)

Pilot Melroy is now reconfiguring helium purge for the main propulsion system. Also, the booster test conductor has started a gaseous nitrogen purge into the aft skirts of the solid rocket boosters for launch.

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

The cross-feed valves between the twin orbital maneuvering system engines on the shuttle's tail have been configured for flight.

2225 GMT (6:25 p.m. EDT)

Pilot Pam Melroy is configuring the displays inside Discovery's cockpit for launch. Also, Mission Control in Houston is loading Discovery's onboard computers with the proper guidance parameters based on the projected launch time.

2221 GMT (6:21 p.m. EDT)

T-minus 20 minutes and counting. The countdown has resumed after a 19-minute hold, some 9 minutes longer than planned due to console problem in the firing room. 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 about 7:17 p.m. EDT (2317 GMT).

Discovery'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.

2219 GMT (6:19 p.m. EDT)

The reinitialization of the backup console now complete. Standing by the resume the count.

2214 GMT (6:14 p.m. EDT)

The backup console in the firing room has been activated. After some testing to ensure all is well, the countdown will be allowed to restart from the T-minus 20 minute mark.

2212 GMT (6:12 p.m. EDT)

Countdown clocks are still holding at T-minus 20 minutes while a couple members of the launch team are moving from the a problematic console to a spare. That is keeping the count stopped at this point while the transition is made. The delay occuring now will be made up by shortening the planned hold at T-minus 9 minutes.

2208 GMT (6:08 p.m. EDT)

The countdown will not resume as planned at T-minus 20 minutes. A console in the firing room has gone down and the uses of that station is moving to the "hot spare" console. The transition will take 15 to 20 minutes to complete, and the countdown cannot resume until that move is finished.

The time used up in this delay will be removed from the near-45 minute scheduled hold at T-minus 9 minutes so Discovery can remain on track for blastoff tonight at 7:17 p.m. EDT.

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

The updated launch window has just been announced by Shuttle Test Director Steve Altemus. The window extends from 7:13:16 to 7:21:10 p.m. EDT. A further update based upon the final radar tracking of the international space station's orbit will be made once the countdown reaches the T-minus 9 minute hold if needed. Also, the hold will extended to synch up with the preferred launch time near the middle of the window.

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

T-minus 20 minutes and holding. The countdown has paused for a 10-minute built-in hold. Launch remains scheduled for 2317 GMT (7:17 p.m. EDT). There are no technical problems and weather conditions are looking more promising at this time. The Air Force-controlled Range reports all assets are ready and the danger areas are clear.

During this built-in hold, all computer programs in Firing Room 3 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.

2151 GMT (5:51 p.m. EDT)

Commander Brian Duffy has pressurized the gaseous nitrogen system for Atlantis' Orbital Maneuvering System engines, and pilot Pam Melroy has activated the gaseous nitrogen supply for the orbiter's Auxiliary Power Units' water boilers.

2144 GMT (5:44 p.m. EDT)

At this time, the ground pyro initiator controllers (PICs) are scheduled to be powered up. 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. Discovery's two Enhanced Master Events Controllers will be tested, too. They relay the commands from the shuttle's computers to ignite, and then separate the boosters and external tank during launch.

In the firing room, the mainline activation of the ground launch sequencer has been completed. The GLS is the master computer program that controls the final nine minutes of the countdown.

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

The Orbiter Closeout Crew has completed its work with Discovery's hatch locked for flight, leak checks complete and the pad's White Room configured for launch. The team will now depart the pad, leaving only the seven astronauts at the seaside complex. Liftoff still set for about 7:17 p.m. EDT (2317 GMT).

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

The two solid rocket booster recovery ships -- the Freedom Star and Liberty Star -- are on station in the Atlantic Ocean about 140 miles northeast of Kennedy Space Center, off the coast of Jacksonville, Florida. 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.

The ships sailed from Port Canaveral for a second time to support Discovery's launch on Sunday night at 6:30 p.m. EDT. This afternoon they moved into a position about 7 1/2 miles from the predicted impact zone to perform an electronic search of the area to ensure it is cleared of all shipping traffic.

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

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

T-minus 1 hour and counting. Clocks ticking along to tonight's scheduled launch at 7:17 p.m. EDT (2317 GMT). The pre-flight alignment of Discovery's Inertial Measurement Units is now beginning, and will be completed by the T-minus 20 minute mark. 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 Discovery and Mission Control during the first few minutes of flight. Coverage then is handed to a NASA Tracking and Data Relay Satellite in space.

The latest launch weather forecast for Kennedy Space Center has been improved to an 80 percent chance of acceptable conditions tonight. The forecast calls for a few clouds at 4,000, scattered at 6,500 and scattered at 25,000 feet, 7 miles visibility, northeasterly winds from 030 degrees 12 peaking to 18 knots, a temperature of 72 degrees F and a slight chance of rainshowers.

2100 GMT (5:00 p.m. EDT)

The crew compartment of Discovery is now about to be pressurized for leak checks.

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

Discovery's crew module hatch has been closed. Pressure and leak checks will be performed to ensure a good seal on the hatch for tonight's launch.

2047 GMT (4:47 p.m. EDT)

The Orbiter Closeout Crew is now removing platforms used by the astronauts to board the shuttle today in advance of swinging shut Discovery's hatch.

2037 GMT (4:37 p.m. EDT)

With all the astronauts strapped aboard, the Discovery crew is conducting voice communications checks.

Also in the countdown, the booster test conductor will soon verify the chamber pressure in the twin solid rocket motors. Sensors measure pressure in the thrust chambers at nozzles of the boosters. The data tells onboard computers when the boosters have consumed their solid-fuel propellant and should be separated in-flight.

There are some rainshowers moving through the local Kennedy Space Center area. However, meteorologists still hope conditions will be acceptable for launch tonight at 7:17 p.m. EDT (2317 GMT).

2027 GMT (4:27 p.m. EDT)

The final Discovery astronaut has boarded the shuttle today. Bill McArthur, mission specialist No. 2 and flight engineer, has now entered the hatch. He will sit in the flight deck center seat, giving an extra set of eyes to aid the command and pilot watch displays and switches during launch and landing.

You can read McArthur's biography in our Crew Report.

2013 GMT (4:13 p.m. EDT)

Discovery's mission specialist No. 1, Japanese astronaut Koichi Wakata, has board the shuttle. He will sit in the flight deck aft right seat.

You can read Wakata's biography in our Crew Report.

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

Michael Lopez-Alegria, mission specialist No. 4, is now onboard Discovery. He will sit in the middeck center seat.

You can read Lopez-Alegria's biography in our Crew Report.

2004 GMT (4:04 p.m. EDT)

Discovery's mission specialist No. 3, Jeff Wisoff, has boarded the shuttle. He will sit in the middeck left seat.

You can read Wisoff's biography in our Crew Report.

2002 GMT (4:02 p.m. EDT)

Discovery's pilot, Pam Melroy, has entered the shuttle's hatch. She will sit in the flight deck forward right seat.

You can read Melroy's biography in our Crew Report. She will come just the third woman to pilot the space shuttle.

1954 GMT (3:54 p.m. EDT)

Mission specialist No. 1 Leroy Chiao has boarded Discovery. Chiao will sit in the middeck right seat.

You can read Chiao's biography in our Crew Report.

1952 GMT (3:52 p.m. EDT)

Discovery commander Brian Duffy has become the first astronaut to enter the shuttle today. He will sit in the flight deck forward left seat.

You can read Duffy's biography in our Crew Report.

1946 GMT (3:46 p.m. EDT)

Discovery's seven astronauts have taken the elevator up the fixed service structure at launch pad 39A to the 195-foot level. This is 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 Discovery's crew module hatch.

2043 GMT (3:43 p.m. EDT)

The shuttle astronauts have arrived at launch pad 39A.

1929 GMT (3:29 p.m. EDT)

Discovery's astronauts have embarked on the 20-minute ride in the "AstroVan" from their quarters to launch pad 39A on the edge of the Atlantic Ocean. This is the second time the seven-member crew as gone to the pad in their attempt to begin an action-packed 11-day space flight that will continue construction of the international space station and four spacewalks.

The AstroVan convoy will stop at the Launch Control Center for the NASA management and NASA astronaut Kent Rominger to exit the Astrovan. The managers will take their positions in Firing Room 3 while Rominger heads over to the Shuttle Landing Facility to begin weather reconnaissance flights in a T-38 jet. He will later switch to the modified Gulfstream jet, which is known as the Shuttle Training Aircraft because its flying characteristics are very similar to the space shuttle.

Romginer's input on the weather is expected to be crucial tonight as he evaluates cloud ceiling and rainshowers around the runway here at Kennedy Space Center.

1922 GMT (3:22 p.m. EDT)

T-minus 3 hours and counting. Countdown clocks have resumed following this two-hour planned hold. The count will continue to T-minus 20 minutes where the next built-in hold will occur. A final hold is planned at T-minus 9 minutes. Launch is still scheduled for about 2317 GMT (7:17 p.m. EDT). There are no technical problems being worked, however, the weather looks like it will be a challenge again this evening.

The astronauts are expected to depart their quarters for the launch pad in about five minutes.

Discovery stands fully fueled and ready for launch from pad 39A at Kennedy Space Center, Fla. The loading of 528,000 gallons of liquid oxygen and liquid hydrogen into the external tank began at 1439 GMT (10:39 a.m. EDT). The operation went smoothly and was completed at 1730 GMT (1:30 p.m. EDT). A stable replenishment mode then started to continuously top-off the respective tanks within the external tank through the final minutes of the countdown.

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. Currently, the six-person team, comprised of five engineers and one safety official, is 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 380-foot 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, which is headed by Greg Katnik of the Kennedy Space Center, is also looking for any loose debris that could possibly fly up and strike the launch vehicle. 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 vehicle 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 teammember is also responsible for photo documentation.

Each member of the Final Inspection Team is in constant contact with NASA Test Director Steve Altemus in Firing Room 3.

The team wears the highly visible day-glo-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, Greg Katnik will meet with NASA Launch Director Mike Leinbach, the Mission Management Team, and engineering directors in the launch control center. Katnik will give the managers a full and detailed report on the team's 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.

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.

1910 GMT (3:10 p.m. EDT)

The seven astronauts are finishing with their suit-up process, donning the day-glow orange partial pressure suits inside the crew quarters here at Kennedy Space Center. They are due to depart for the launch pad at 3:27 p.m. EDT.

Again, there are no technical problems being worked, the shuttle is fully fueled and the countdown marches on towards a 7:17 p.m. EDT liftoff this evening. However, weather could be a problem not only here in Florida but at abort landing sites overseas.

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

A weather briefing just given to the astronauts does not paint a rosy picture for tonight's launch attempt of Discovery. Overall there is still a 60 percent chance of accceptable conditions here at Kennedy Space Center with the main threats being a low cloud ceiling at 4,000 feet and rainshowers within 20 nautical miles, which would violate rules protecting safe conditions at the emergency runway in case Discovery would have to abort the launch.

In addition there is a forecast for clouds and rain at the abort landing sites across the Atlantic Ocean in Spain and Morocco. Forecasters are calling for showers at Zaragoza, Spain, low clouds, rain and high winds at Moron, Spain, and the chance of low clouds at Ben Guerir in Morocco. One site must have favorable weather for Discovery to be cleared for launch.

So conditions will be watched closely and NASA will continuing counting down to the scheduled 7:17 p.m. EDT (2317 GMT) launch time in hopes of acceptable weather.

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

Two teams have been dispatched to launch pad 39A following the completing of today's three-hour fueling operation. The pad is cleared of all workers while the external tank was loaded with its half-million gallons of liquid oxygen and liquid hydrogen.

The Orbiter Closeout Crew are responsible for readying Discovery's crew module for the astronauts' arrival about 90 minutes from now. They will also assist the seven astronauts to get strapped into their seats and then close and lock the shuttle's hatch.

The Final Inspection Team will perform a thorough examination of the shuttle and launch pad in a check for ice formation after fueling, and look for any loose debris that could cause a problem at liftoff.

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

Space shuttle Discovery has been fueled and the NASA reports there are no technical problems standing in the way of launch tonight at 7:17 p.m. EDT. Weather conditions are still being watched with crosswinds at the emergency shuttle runway here at Kennedy Space Center the main threat. A light rain shower is currently passing through the local area but meteorologists say clearer skies will move later in the day.

1533 GMT (11:33 a.m. EDT)

Engineers removed a potentially dangerous piece of debris from the shuttle Discovery's external tank early today and refueled the ship for a fifth attempt to launch a critical space station assembly mission. Read our latest story for a full update.

1450 GMT (10:50 a.m.)

Super-cold rocket fuel is now flowing into space shuttle Discovery's giant orange external tank as the countdown continues for liftoff tonight at about 7:17 p.m. EDT (2317 GMT) from Kennedy Space Center's launch pad 39A.

Stationed in the safe quarters of the Launch Control Center some 3 1/2 miles from the pad, engineers began the of loading Discovery's external fuel tank with 528,000 gallons of liquid hydrogen and liquid oxygen at 10:39 a.m. EDT (0419 GMT). The process will take three-hours to complete as the cryogenics are pumped from storage spheres at the pad, through feed lines to the mobile launcher platform, into Discovery's aft compartment and finally into the external fuel tank.

This is the second time in the five launch attempts for Discovery that fueling has commenced. The other three times the scrub was called prior to this point in the countdown.

The external tank was drained of its fuel last night after the launch postponement so the rotating service structure could be moved around the shuttle, work platforms set up and the debris grabbed that created the scrub -- an errant pin lodged near a fuel line. The pin was picked up at around 4 a.m. EDT this morning, clearing the way for tonight's launch attempt.

The seven astronauts, meanwhile, were awakened at 6:42 a.m. EDT to begin final preparations for their 11-day voyage in space. We will next see the crew, commanded by Brian Duffy, at 2:17 p.m. EDT (1817 GMT) when they sit down for a snack and traditional pre-launch photo opportunity in the dining room of the Operations & Checkout Building. A quick weather briefing will follow a half-hour later. The astronauts will then beginning donning the partial-pressure spacesuits before departing their quarters for the launch pad at 3:27 p.m. EDT.

1420 GMT (10:20 a.m.)

Fueling is expected to get underway at around 10:50 a.m. EDT. There are still some workers at the launch pad taking pictures of a recently-replaced tile around one of the external tank umbilical doors on the belly of Discovery. NASA says this is not an issue for launch, but the tile needed to be documented because some tape was seen dangling from it. The shuttle is covered with thousands of tiles that shield the craft and astronauts from the intense heat during reentry back into Earth's atmosphere.

1410 GMT (10:10 a.m.)

NASA mission managers have given the OK to begin fueling Discovery for tonight's launch at 7:17 p.m. EDT (2317). Loading of the external fuel tank should start shortly.

The space agency says it is not working any technical problems with the shuttle and the weather forecast still shows a 60 percent chance of acceptable conditions tonight. You can see the forecast in our updated weather page.

1320 GMT (9:20 a.m.)

Launch pad workers this morning did retrieve a small metal pin that had fallen from ground support equipment and lodged itself on Discovery around the fuel lines running between the shuttle and external tank.

Mission managers are currently gathered for their standard pre-fueling meeting before giving the launch team approval to load the external fuel tank with a half-million gallons of liquid oxygen and liquid hydrogen for tonight's launch attempt. Fueling is due to begin in about an hour.

Liftoff remains set for 7:17 p.m. EDT (2317 GMT).

0915 GMT (5:15 a.m.)

The rotating service structure has begun to retract from Discovery, presumably after workers removed the mislaid ground support equipment pin that caused yesterday's launch scrub. The work appears to be running about an hour behind schedule.

0515 GMT (1:15 a.m.)

At launch pad 39A, the rotating service structure is being swung back into position around the space shuttle Discovery so workers can remove the stray metal pin that forced NASA to abandon Tuesday's launch attempt. The gantry-like structure began its slow move a few minutes ago, about an hour later than expected.

Once the structure is in place, work platforms will be extended so launch pad crews can reach the mislaid pin, which is lodged at the base of the external fuel tank where it attaches to the shuttle.

TUESDAY, OCTOBER 10, 2000

Clearly frustrated, NASA managers Tuesday ordered a fourth launch delay for the hard-luck shuttle Discovery after engineers spotted a small but potentially dangerous metal pin lodged in an inaccessible area at the base of the ship's external fuel tank. Read our full story.

We have also posted a video clip of the scrub being announced and a clip describing the pin.

2259 GMT (6:59 p.m. EDT)

The seven astronauts are now climbing out of Discovery following tonight's scrub. They will be headed back to the crew quarters for the night.

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

Managers are putting together a work schedule to remove the piece of debris and still have Discovery ready for another launch attempt on Wednesday evening. The plan begins with the seven astronauts exiting the shuttle over the next half-hour, followed by draining the half-million gallons of liquid oxygen and liquid hydrogen from the external fuel tank. The cocoon-like rotating service structure will then be moved into position around Discovery. NASA believes workers should be able to reach the small pin and grab it by 4 a.m. EDT tomorrow.

The countdown would then be restarted for blastoff tomorrow at about 7:17 p.m. EDT (2317 GMT).

2231 GMT (6:31 p.m. EDT)

SCRUB! NASA Launch Director Mike Leinbach just announced Discovery will not fly tonight because of the piece of debris found around the liquid oxygen feed line between the shuttle and external tank. Officials said they could not be assured the small pin would not strike the shuttle or tank during engine ignition or flight.

Tomorrow's launch time is targeted for 7:17 p.m. EDT (2317 GMT). The weather forecast is calling for a 60 percent chance of acceptable conditions.

2229 GMT (6:29 p.m. EDT)

The updated launch window has just been announced by Shuttle Test Director Steve Altemus. The window extends from 7:38:33 to 7:47:03 p.m. EDT. A further update based upon the final radar tracking of the international space station's orbit will be made once the countdown reaches the T-minus 9 minute hold if needed.

2224 GMT (6:24 p.m. EDT)

T-minus 20 minutes and holding. The countdown has paused for a 10-minute built-in hold. Launch remains scheduled for 2340 GMT (7:40 p.m. EDT). However, mission managers are still assessing the debris on the fuel line between the shuttle and external tank with no decisions made yet.

During this built-in hold, all computer programs in Firing Room 3 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.

2217 GMT (6:17 p.m. EDT)

At this time, the ground pyro initiator controllers (PICs) are scheduled to be powered up. 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. Discovery's two Enhanced Master Events Controllers will be tested, too. They relay the commands from the shuttle's computers to ignite, and then separate the boosters and external tank during launch.

Also, commander Brian Duffy has pressurized the gaseous nitrogen system for Atlantis' Orbital Maneuvering System engines, and pilot Pam Melroy has activated the gaseous nitrogen supply for the orbiter's Auxiliary Power Units' water boilers.

In the firing room, the mainline activation of the ground launch sequencer has been completed. The GLS is the master computer program that controls the final nine minutes of the countdown.

2207 GMT (6:07 p.m. EDT)

The ongoing analysis of where this piece of debris might go if Discovery is cleared to launch in its current position around the liquid oxygen feed line between the shuttle and external tank. NASA says it does not have a long enough object to reach up and grab the small metal pin. It is 40 feet above the mobile launcher platform surface.

Currently engineers say that at engine ignition the pin could fall down to the launcher platform and might bounce up and hit the vehicle. If it were to hang through launch, analysis shows that through Mach 2.5 the pin would be most likely to fall towards the external fuel tank aft dome. After Mach 2.5, the pin would probably fall towards the shuttle's body flap.

2200 GMT (6:00 p.m. EDT)

No update on the debris -- a small pin -- that has been found around the liquid oxygen feed line running between Discovery and the external fuel tank.

2148 GMT (5:48 p.m. EDT)

Managers are currently discussing what to do about the debris found around the liquid oxygen feed line running between the shuttle and external fuel tank by the inspection team at launch pad 39A. This pin is in a location not reachable without scrubbing the launch and moving access platforms into place. The concern is the pin could fly free at ignition and damage Discovery.

Meanwhile in the countdown, 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 Discovery and Mission Control during the first few minutes of flight. Coverage then is handed to a NASA Tracking and Data Relay Satellite in space.

Also the pre-flight alignment of Discovery's Inertial Measurement Units is now beginning, and will be completed by the T-minus 20 minute mark. 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.

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

The Final Inspection Team has found a metal pin lodged on the external tank support structure near the liquid oxygen support strut. The pin has a four-inch shaft, a three-inch handle, an attached tether, is estimated to be weigh 8-ounces and is thought to be part of ground support equipment. Analysis is underway to determine if the pin were to fall free during launch, if it did, where would it go and what damage might be caused by such a debris impact to the shuttle.

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

Weather forecasters have again improved the precentage of acceptable conditions. There is now a 70 percent chance weather will allow Discovery to blast off on time at 7:40 p.m. EDT tonight. The concerns are crosswinds and low clouds at the emergency runway here at Kennedy Space Center.

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

Discovery's crew module hatch has been closed. Pressure and leak checks will be performed to ensure a good seal on the hatch for tonight's launch.

Activities are continuing smoothly this afternoon at pad 39A as NASA counts down to liftoff at 7:40 p.m. EDT (2340 GMT).

2111 GMT (5:11 p.m. EDT)

The Orbiter Closeout Crew is currently removing platforms used by the astronauts to board the shuttle today in advance of swinging shut Discovery's hatch.

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

With all the astronauts strapped aboard, the Discovery crew is conducting voice communications checks.

Also in the countdown, the booster test conductor will soon verify the chamber pressure in the twin solid rocket motors. Sensors measure pressure in the thrust chambers at nozzles of the boosters. The data tells onboard computers when the boosters have consumed their solid-fuel propellant and should be separated in-flight.

2049 GMT (4:49 p.m. EDT)

The final Discovery astronaut has boarded the shuttle today. Bill McArthur, mission specialist No. 2 and flight engineer, has now entered the hatch. He will sit in the flight deck center seat, giving an extra set of eyes to aid the command and pilot watch displays and switches during launch and landing.

You can read McArthur's biography in our Crew Report.

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

Discovery's mission specialist No. 1, Japanese astronaut Koichi Wakata, has board the shuttle. He will sit in the flight deck aft right seat.

You can read Wakata's biography in our Crew Report.

2036 GMT (4:36 p.m. EDT)

Michael Lopez-Alegria, mission specialist No. 4, is now onboard Discovery. He will sit in the middeck center seat.

You can read Lopez-Alegria's biography in our Crew Report.

2027 GMT (4:27 p.m. EDT)

Discovery's mission specialist No. 3, Jeff Wisoff, has boarded the shuttle. He will sit in the middeck left seat.

You can read Burbank's biography in our Crew Report.

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

Discovery's pilot, Pam Melroy, has entered the shuttle's hatch. She will sit in the flight deck forward right seat.

You can read Melroy's biography in our Crew Report. She will come just the third woman to pilot the space shuttle.

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

Mission specialist No. 1 Leroy Chiao has boarded Discovery. Chiao will sit in the middeck right seat.

You can read Chiao's biography in our Crew Report.

2014 GMT (4:14 p.m. EDT)

Discovery commander Brian Duffy has become the first astronaut to enter the shuttle today. He will sit in the flight deck forward left seat.

You can read Duffy's biography in our Crew Report.

Also, we have posted a QuickTime video clip of the astronauts departing their quarters.

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

Discovery's seven astronauts have taken the elevator up the fixed service structure at launch pad 39A to the 195-foot level. This is 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 Discovery's crew module hatch.

2006 GMT (4:06 p.m. EDT)

The shuttle astronauts have arrived at launch pad 39A.

2000 GMT (4:00 p.m. EDT)

Discovery stands fully fueled and ready for launch from pad 39A at Kennedy Space Center, Fla. The loading of 528,000 gallons of liquid oxygen and liquid hydrogen into the external tank began at 1602 GMT (12:02 p.m. EDT). The operation went smoothly and was completed at 1859 GMT (2:59 p.m. EDT). A stable replenishment mode then started to continuously top-off the respective tanks within the external tank through the final minutes of the countdown.

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. Currently, the six-person team, comprised of five engineers and one safety official, is 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 380-foot 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, which is headed by Greg Katnik of the Kennedy Space Center, is also looking for any loose debris that could possibly fly up and strike the launch vehicle. 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 vehicle 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 teammember is also responsible for photo documentation.

Each member of the Final Inspection Team is in constant contact with NASA Test Director Steve Altemus in Firing Room 3.

The team wears the highly visible day-glo-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, Greg Katnik will meet with NASA Launch Director Mike Leinbach, the Mission Management Team, and engineering directors in the launch control center. Katnik will give the managers a full and detailed report on the team's 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.

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.

1951 GMT (3:51 p.m. EDT)

Discovery's astronauts are on their way to the launch pad. They have departed the Operations & Checkout Building, which serves as the living quarters for the flight crew while at Kennedy Space Center. The ride out to pad 39A, on the edge of the Atlantic Ocean, will take about 20 minutes.

The convoy will stop at the Launch Control Center for the NASA management and NASA astronaut Kent Rominger to exit the Astrovan. The managers will take their positions in Firing Room 3 while Rominger heads over to the Shuttle Landing Facility to begin weather reconnaissance flights in a T-38 jet. He will later switch to the modified Gulfstream jet, which is known as the Shuttle Training Aircraft because its flying characteristics are very similar to the space shuttle.

Romginer's input on the weather is expected to be crucial tonight as he evaluates crosswinds and cloud ceiling conditions at the runway here at Kennedy Space Center.

1944 GMT (3:44 p.m. EDT)

T-minus 3 hours and counting. Countdown clocks have resumed following this two-hour planned hold. The count will continue to T-minus 20 minutes where the next built-in hold will occur. A final hold is planned at T-minus 9 minutes. Launch is still scheduled for about 2340 GMT (7:40 p.m. EDT). There are no technical problems being worked, however, the weather looks like it will be a challenge this evening.

The astronauts are expected to depart their quarters for the launch pad in about five minutes.

TUESDAY, OCTOBER 10, 2000
1912 GMT (3:12 p.m. EDT)

A weather briefing currently being given to the astronauts still indicates that low clouds and crosswinds are a concern for tonight's launch attempt at Kennedy Space Center. The forecast is currently calling for clouds scattered at 4,000, broken at 6,500 and overcast at 25,000 feet, 7 miles visibility and northeasterly winds from 040 degrees at 10 peaking to 16 knots.

The problems tonight, which is why there is a 50-50 percent chance of acceptable weather, will be crosswinds and a low cloud ceiling at KSC's Shuttle Landing Facility. The runway would be used by Discovery in an emergency if the shuttle had to abort the launch and return to Earth in the first minutes of flight.

Meteorologists say the winds could be gusting to up 16 knots, which is above the 15-knot limit. Also, the cloud deck at 4,000 feet could become broken instead of scattered, thus constituting a cloud ceiling.

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

Two teams have been dispatched to launch pad 39A following the completing of today's three-hour fueling operation. The pad is cleared of all workers while the external tank was loaded with its half-million gallons of liquid oxygen and liquid hydrogen.

The Orbiter Closeout Crew are responsible for readying Discovery's crew module for the astronauts' arrival about 90 minutes from now. They will also assist the seven astronauts to get strapped into their seats and then close and lock the shuttle's hatch.

The Final Inspection Team will perform a thorough examination of the shuttle and launch pad in a check for ice formation after fueling, and look for any loose debris that could cause a problem at liftoff.

1859 GMT (2:59 p.m. EDT)

Fueling of Discovery is now complete. The liquid hydrogen and liquid oxygen tanks inside of the shuttle's orange external fuel tank are now in stable replenish mode and being topped off through the remainder of the countdown to replace the super-cold cryogenics as they naturally boil away.

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

As the three-hour process to load Discovery's external fuel tank with a half-million gallons of liquid oyxgen and liquid hydrogen continues smoothly, weather forecasters have improve the odds of the shuttle being able to launch tonight. Meteorologists have updated the officials launch forecast to indicate a 50 percent chance of acceptable conditions. The previous forecast called for just a 30 percent chance of good weather. The weather concerns continue to be strong crosswinds and low clouds at the shuttle runway here at Kennedy Space Center that will be used in the event a problem causes the launch to be aborted.

Read our morning update story.

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

A follow-up test of the Pyrotechnic Initiator Controller system at launch pad 39A has been performed successfully this afternoon after a last-minute fix-it team resolved a problem with a circuit breaker. The PIC system fires the explosive bolts that release Discovery from the launch pad at liftoff. With this glitch now put to rest and fueling of Discovery underway, the countdown is marching along towards a planned 7:40 p.m. EDT (2340 GMT) liftoff tonight.

There are no other technical problems to report. However, weather remains a major threat with a 70 percent chance of conditions prohibiting launch.

1602 GMT (12:02 p.m. EDT)

The chilldown process has started at launch pad 39A as fueling begins for tonight's space shuttle launch. Chilldown is a procedure in which a small amount of the super-cold liquid oxygen and liquid hydrogen is released from the pad storage tanks to thermally condition the propellant lines into the shuttle. Once lines are conditioned, the flow rate will increase and Discovery's bullet-shaped external tank will loaded with a half-million gallons of cryogenics.

Fueling is starting at nearly the last moment today after a delay over an hour because a circuit breaker problem in the launch pad's Pyrotechnic Initiator Controller system. A team that went to the pad believe they have fixed the glitch but a test of the system will need to be performed a little that this afternoon before the issue can be put to rest.

1554 GMT (11:54 a.m. EDT)

Engineers report the troublesome circuit breaker at launch pad 39A has been closed and the repair team is now leaving the oceanside complex so fueling can begin. NASA still shooting for a 7:40 p.m. EDT (2340 GMT) launch tonight of Discovery on the 100th shuttle flight.

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

A team of engineers are still at launch pad 39A trying to resolve a last-minute problem with the Pyrotechnic Initiator Controller system. The PIC system fires explosive bolts to release shuttle Discovery from the pad at the moment of liftoff.

Earlier this morning the launch team became concerned with a circuit breaker in a PIC rack inside the mobile launcher platform that the shuttle sits on. A crew was dispatched to the pad to examine the circuit breaker first hand.

The loading of Discovery's external fuel tank has been delayed for the more than an hour while this extra work has been ongoing. The hazardous fueling process cannot begin with workers at the pad. Officials say fueling needs to get underway by about 12 p.m. EDT or else tonight's launch attempt will have to be scrubbed.

"It looks like we are going to be right on the edge," NASA spokewoman Lisa Malone said of the schedule crunch if the problem can be resolved and fueling started.

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

The loading of shuttle Discovery's external fuel tank has still not started. Engineers continue troubleshooting the launch pad's Pyrotechnic Initiator Controller system. Fueling needs to get underway by around 12 p.m. EDT in order to make tonight's tight launch window.

1444 GMT (10:44 a.m. EDT)

T-minus 6 hours and counting. The countdown has been restarted after a one-hour built-in hold. Clocks will now tick down to T-minus 3 hours where a two-hour hold is planned. Launch remains scheduled for about 7:40 p.m. EDT (2340 GMT) tonight with the exact liftoff time to be refined in the final countdown based upon radar tracking of the international space station.

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

Fueling of Discovery is on a temporary hold while engineers troubleshoot a reading received from the Pyrotechnic Initiator Controller (PIC) system on the mobile launcher platform on which the shuttle sits at launch pad 39A. The PIC system is of utmost importance for a shuttle countdown because it fires the explosive bolts at launch to release the solid rocket boosters from the holddown points as well as other umbilicals connecting the vehicle to the ground.

A NASA spokesman says it does not appear the issue will scrub today's launch and that officials simply wanted to take some additional time to examine the PIC reading. Fueling is expected to start around 11 a.m. EDT or soon thereafter.

1410 GMT (10:10 a.m. EDT)

NASA officials have given the approval to begin loading space shuttle Discovery with 528,000 gallons of liquid oxygan and liquid hydrogen for tonight's launch. Confirmation that the three-hour operation is expected shortly. Meanwhile, the weather forecast remains unchanged with a 70 percent chance of conditions prohibiting launch.

0910 GMT (5:10 a.m. EDT)

The shuttle launch team in Firing Room 3 of Kennedy Space Center's Complex 39 Launch Control Center has resumed the countdown for tonight's scheduled 7:40 p.m. EDT (2340 GMT) blastoff of Discovery. This is the fourth attempt at launching Discovery since the initial postponement last Thursday.

At launch pad 39A, the winds have subsided substantially since yesterday morning when routine work was halted because of the blustery conditions. Just minutes ago the gaseous oxygen vent hood -- the "beanie cap" -- was lowered over the tip of the shuttle's external fuel tank. That was a critical milestone in the countdown not accomplished on Monday because the winds were too strong.

The loading of the fuel tank with a half-million gallons of super-cold liquid oxygen and liquid hydrogen is due to begin at about 10:15 a.m. EDT. In the previous three launch attempts, the countdowns never progressed far enough for fueling to commence.

The seven shuttle astronauts, meanwhile, are due to be awakened at 7:05 a.m. EDT to begin their launch day activities. Their first public event is scheduled for 2:40 p.m. EDT when the photo opportunity is planned in the dining room of crew quarters. After a weather briefing, the astronauts will suit up and then depart for the launch pad at 3:50 p.m. EDT. Discovery's crew module hatch will be closed for flight at 5:45 p.m. EDT.

MONDAY, OCTOBER 9, 2000
1540 GMT (11:40 a.m. EDT)

After weekend work to resolve two technical issues, the hard-luck shuttle Discovery was grounded again today, this time by high winds at the launch pad that prevented engineers from completing preparations to fuel the ship for take off. Read our full scrub story for more details on the postponement and NASA's options for further launch opportunities.

1420 GMT (10:20 a.m. EDT)

Scrub turnaround procedures are underway Kennedy Space Center this morning following the postponement of shuttle Discovery's scheduled launch tonight. Officials were forced to cancel the launch attempt because strong winds at Discovery's oceanside pad were too high to move the gaseous oxygen vent arm into place next to the shuttle's external fuel tank and lower the vent hood in advance of fueling operations. The peak wind measured at the pad overnight was 44.6 knots. The limit is 42 knots.

The swing-arm was due to be extended this morning at 2 a.m. EDT. The countdown had margin so the extension could have been delayed to 5 a.m. EDT without delaying the start of fueling at 10:45 a.m. EDT. NASA says by 8 a.m. EDT all the contigency time in the schedule had been used up and there was no longer any chance of getting the arm in position, finish up the remaining pad work and still fuel Discovery to make tonight's tight launch window.

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

With today's launch postponement, we have posted the revised countdown timeline, ascent events chart and astronauts' flight plan.

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

SCRUB! The launch of space shuttle Discovery has been scrubbed for 24 hours because high winds held up routine work at pad 39A. Workers were not able to position the gaseous oxygen vent hood -- commonly referred to as the "beanie cap" -- over the tip of the bullet-shaped external fuel tank. The cap has to be lowered over the tank's top before fueling begins in order to vent away oxygen vapors. Officials said time ran out this morning to get the beanie cap in place and still make a launch attempt tonight at 8:05 p.m. EDT.

Meanwhile, the weather forecast remained very iffy with a 70 percent chance that crosswinds and low clouds would have prevented launch tonight anyway.

Liftoff on Tuesday will be targeted for 7:40 p.m. EDT with the exact liftoff time to be determine in the final countdown based upon the latest radar tracking of the international space station's orbit. Tuesday's weather forecast, however, is no better than tonight's.

SUNDAY, OCTOBER 8, 2000
1820 GMT (2:20 p.m. EDT)

NASA managers today cleared the repaired Discovery for a delayed launch attempt Monday evening to kick off the 100th shuttle flight, the most complex space station assembly mission yet. But forecasters are predicting a 70 percent chance of high crosswinds could prompt another delay. Read our full story.

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

Cryogenic liquid oxygen and liquid hydrogen reactants are being pumped into space shuttle Discovery's fuel cell storage tanks this morning at launch pad 39A. The operation began before dawn today and should conclude shortly.

The latest weather forecast is unchanged with only a 30 percent chance of acceptable conditions for a Monday night launch at 8:05 p.m. EDT. The concerns are strong crosswinds and low clouds.

Meanwhile, the engineering analysis continues for the external fuel tank attach bolt problem seen during the last shuttle mission. NASA reports there has not been any update to this issue since Friday.

0115 GMT (9:15 p.m. EDT)

Space shuttle Discovery's aft engine compartment has been closed for flight once again now that the faulty valve has been replaced. The aft was reopened Friday for the valve removal.

Known as a pogo accumulator recirculation valve, the two-inch diameter valve is one of two in Discovery's liquid oxygen plumbing that acts as a shock absorber and prevents propellant from surging through the fuel lines during launch.

On Saturday afternoon workers made their final inspections of the aft compartment and then installed the access door.

Efforts are now underway in advance of pumping cryogenic liquid oxygen and liquid hydrogen reactants into the shuttle's three fuel cells. Initial work is complete and teams are looking ahead to the actual loading, which is scheduled to start around 6 a.m. EDT (1000 GMT).

SATURDAY, OCTOBER 7, 2000
1430 GMT (10:30 a.m. EDT)

Shuttle technicians have successfully removed and replaced a faulty vibration-suppression fuel valve inside Discovery's aft engine compartment. The job was completed at 1 a.m. EDT today and subsequent leak checks found no problems in the shuttle's plumbing. Functional checks of the valve were underway before sunrise today, and once complete, engineers will begin backing out of the aft compartment. The access door on the side of Discovery is due to be installed later this afternoon.

The schedule for the rest of Saturday calls for the start of preparations to load Discovery's three power-generating fuel cells. The fuel cell storage tanks were drained of the liquid oxygen and liquid hydrogen early Friday morning after the launch postponement. The reloading is expected to start at 6 a.m. EDT on Sunday. The cryogenic reactants are combined to produce electricity to power the shuttle's systems and drinking water as a byproduct for the astronauts during the 11-day mission in space.

Discovery remains scheduled for launch on Monday at about 8:05 p.m. EDT (0005 GMT Tuesday) with the exact liftoff time to be determine in the final countdown based upon radar tracking of the international space station's orbit.

Weather conditions on Monday night, however, remain a real concern as forecasters are predicting a 70 percent chance strong winds and low clouds will scrub the launch. Conditions don't improve any on Tuesday, either, according to the official forecast. The first break in the weather is expected on Wednesday when there is just a 30 percent of unfavorable conditions for launch.

FRIDAY, OCTOBER 6, 2000
1800 GMT (2:00 p.m. EDT)

The weather forecast issued today shows just a 30 percent chance conditions will allow Discovery to blast off on Monday night. Gusty winds at the emergency shuttle runway at Kennedy Space Center and low clouds are predicted as problems on both Monday and Tuesday. Conditions improve greatly on Wednesday with a 70 percent chance of good weather for launch. See the forecast.

1533 GMT (11:33 a.m. EDT)

NASA managers say work to replace a sluggish valve in the shuttle Discovery's engine compartment should be complete by late today, setting the stage for a delayed launch attempt at 8:05 p.m. Monday. But that assumes ongoing assessment work with a suspect bolt can be resolved by Monday morning. Read our full story.

0045 GMT (8:45 p.m. EDT)

MISSION POSTPONED AGAIN. The launch of space shuttle Discovery has been postponed until Monday night so workers can replace a suspect valve in the craft's aft engine compartment, NASA officials decided a short time ago. Monday's target liftoff time is 8:05 p.m. EDT (0005 GMT Tuesday).

The so-called liquid oxygen pogo valve within Discovery's main propulsion system controls the flow rate of propellant and dampens vibrations during launch. Controllers reported the valve operated "sluggishly" during a countdown test Thursday. Further analysis determined the valve needed to be removed and replaced before Discovery could be launched.

Work to gain access to Discovery's cramped three-level engine compartment is now underway. Once the replacement is completed a mass spectrometer test will be performed to ensure there are no leaks around the new valve. This will require an official waiver of NASA rules because such a valve replacement normally calls for an extensive leak test throughout the shuttle plumbing using helium. But the helium leak check would take longer to perform and delay the launch another day or two, something the space agency decided was not necessary.

Thursday's planned launch attempt of Discovery was called off so engineers could double-check a concern with a bolt that did not work as designed during the last shuttle mission (see information below for more details). That issue is still under review tonight.

THURSDAY, OCTOBER 5, 2000
2300 GMT (7:00 p.m. EDT)

The rotating service structure has been rolled back into position around space shuttle Discovery at launch pad 39A this evening.

Meanwhile, engineers continue their analysis work to determine if a retractable bolt on the external tank that failed to work properly on the last shuttle launch is a concern for Discovery's flight. That analysis forced NASA to scrub tonight's planned launch attempt.

In addition, officials still must determine if a suspect valve in Discovery's aft engine compartment is a constraint to launch. The valve showed signs of operating sluggishly during the countdown this morning. If engineers have to open up the aft compartment the earliest Discovery could launch would likely be Monday night. A decision on the valve situation could come later tonight.

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

NASA has released an image that shows the bolt that failed to retract during last month's flight of shuttle Atlantis. We have also posted a QuickTime video clip from today's news conference in which Jim Halsell explains the cause of the delay.

1925 GMT (3:25 p.m. EDT)

Read our full story on today's launch postponement.

Also see the updated astronauts' flight plan and launch events chart.

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

Engineers are studying a second problem that could impact plans to launch Discovery on Friday. A valve in Discovery's main propulsion system which helps control vibrations during ascent is operating sluggishly and engineers may need to reenter Discovery's aft engine compartment for inspections and/or repairs. If engineers do, in fact, reenter the aft compartment NASA would not be able to make another launch attempt until Monday. A decision of how to proceed is expected soon.

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

NASA officials have set up three teams to investigate the bolt problem experienced during the last space shuttle mission. As part of the routine post-flight data review from the STS-106 mission of Atlantis that launched September 8, engineers discovered a bolt that attaches the shuttle to the external fuel tank did not work as expected.

When the explosive nut on the bolt fired as planned to jettison the tank after reaching orbit, the bolt did not retract into the tank as designed. A camera mounted on Atlantis captured a view of the bolt sticking out about two inches and was first noted this week when the film was examined.

Officials are ordering an analysis to determine if this bolt retraction problem happens again whether there would be some sort of collision between the shuttle and tank during separation. No contact occurred in September and tank was jettisoned without incident.

Senior managers said it was best to postpone tonight's launch of Discovery for one day to give engineers more time to sort out the worst-case scenarios if a bolt fails to retract on a future launch. There is currently no reason to believe there is any problem with Discovery's hardware.

Said NASA Launch Integration Manager Jim Halsell: "We don't want to get 'go fever.'"

For now the space agency is hoping to have Discovery cleared for another launch attempt on Friday night at 9:16 p.m. EDT. Officials will get a status report from the three investigative teams tonight.

Check back later today for a full story on the delay and a picture of the extended bolt as seen from a camera on Atlantis that first showed this problem.

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

SCRUB! NASA officials have called off tonight's scheduled launch attempt of Discovery on the 100th shuttle mission due to a last-minute concern with a bolt on the external fuel tank. The launch will be delayed at least 24 hours while engineers study the bolt problem, which occurred during the most recent shuttle mission in September. We will post additional details as soon as they become available.

Friday's launch time is about 9:16 p.m. EDT (0116 GMT Saturday). Weather forecasters are calling for a 60 percent chance of acceptable conditions.

1644 GMT (12:44 p.m. EDT)

The countdown has just resumed from the hold at T-6 hours, but engineers have held up fueling the shuttle Discovery for launch this evening pending resolution of a last-minute concern about the ship's external fuel tank. NASA managers plan to make a decision about whether to proceed with fueling or to delay the flight within the hour.

The problem involves a bolt that retracts during the external tank separation sequence after the shuttle reaches orbit. Analysis of film from a camera aboard Atlantis last month showed one of the bolts in question in that shuttle's external tank failed to fully retract.

The concern is that an extended bolt could cause a shuttle to recontact the tank during the separation procedure. Engineers are assessing records and other data to determine the status of the bolts in Discovery's external fuel tank.

Launch on the 100th shuttle mission is targeted for 9:38:26 p.m. this evening. Fueling had been scheduled to begin shortly after noon, but the procedure has been held up to give engineers more time to assess the bolt issue.

There are no other technical issues of any significance and forecasters are predicting an 80 percent chance of acceptable weather during Discovery's brief launch window. This status report will be updated once a decision has been made one way or the other.

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

NASA managers are discussing a last-minute technical concern with a bolt in the system that connects the shuttle to its fuel tank. They are holding up fueling operations and plan to meet again at 12:45 p.m. EDT (1645 GMT) to decided whether to proceed with launch. The concerns were raised when this type of bolt failed to retract properly during the launch of shuttle Atlantis last month. The bolt is on the shuttle's right-hand side where liquid oxygen enters the vehicle. We will post more information as we get it.

1535 GMT (11:35 a.m. EDT)

NASA managers are meeting right now at the Kennedy Space Center to give the go-ahead for Discovery's launch on the 100th space shuttle flight. A NASA spokesman said earlier this morning he was not aware of any technical issues and the weather was looking good for launch. We have posted the latest detailed weather forecast.

1330 GMT (9:30 a.m. EDT)

Clear skies greeted the space shuttle Discovery this morning as the sun rose over launch pad 39A. The tropical weather that drenched the Kennedy Space Center over the last few days has gone and forecasters improved the chances of acceptable launch weather from 60 to 80 percent.

0800 GMT (4:00 a.m. EDT)

The cocoon-like rotating service structure has been rolled away from space shuttle Discovery at launch pad 39A this morning as NASA counts down to blastoff at 9:38 p.m. EDT (0138 GMT).

Countdown clocks are currently holding as planned at T-minus 11 hours. This 13-hour, 43-minute pause began at 4 p.m. EDT Wednesday and should conclude at 5:43 a.m. this morning.

During this hold, engineers have begun functional checks of Discovery's star tracker navigational devices and activated the Inertial Measurement Units and onboard communications systems. Last-minute packing of astronauts' equipment inside the shuttle also started late last night, as well as an exhaustive check of switches in Discovery's cockpit to ensure they are in the correct positions.

After sunrise today the launch pad 39A area gradually will be cleared of all workers in advance of fueling shuttle Discovery's external fuel tank with a half-million gallons of liquid oxygen and liquid hydrogen. Countdown clocks are slated to enter another planned hold at 10:43 a.m. EDT at the T-minus 6 hour mark. Senior managers will meet a short time later to verify all is in readiness for fueling to commence.

If there are no technical or weather problems, the three-hour process of loading of the bullet-shaped external fuel tank is expected to begin just after noon EDT.

Meanwhile, the astronauts will be awakened at 9:30 a.m. EDT. Their launch day schedule includes breakfast at 10:30 a.m., a final snack and traditional photo opportunity at 4:38 p.m., begin suiting up at 5:08 p.m. and depart quarters for the pad at 5:48 p.m.

WEDNESDAY, OCTOBER 4, 2000
1630 GMT (12:30 p.m. EDT)

Shuttle Discovery's countdown continues to tick smoothly toward blastoff Thursday night. The only concern remains the possibility of showers that could cause a delay. Meteorologists are giving a 60 percent "go" forecast. Read our morning story on the weather.

At launch pad 39A, workers overnight completed loading Discovery's three onboard fuel cells with liquid oxygen and liquid hydrogen cryogenic reactants, which will be combined to generate electricity and drinking water during the 11-day shuttle mission. This morning final efforts to prepare the shuttle's three main engines for tomorrow's fueling operations began, as well as work to close out the tail service masts on the mobile launcher platform that connect to Discovery's aft engine compartment.

TUESDAY, OCTOBER 3, 2000
1630 GMT (12:30 p.m. EDT)

With the shuttle Discovery's countdown underway, forecasters are predicting marginally acceptable weather for launch Thursday night. There are no technical problems of any significance at pad 39A and officials said today weather is the only concern as the agency gears up for its 100th shuttle mission. Read our full story.

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

The countdown for the 100th space shuttle launch has begun at Kennedy Space Center. Clocks began ticking at 12 a.m. EDT in Firing Room 3 of the Complex 39 Launch Control Center. Liftoff of space shuttle Discovery remains scheduled for Thursday at 9:38 p.m. EDT (0138 GMT Friday).

On Monday afternoon workers closed Discovery's payload bay doors. Tonight efforts are underway to close out other parts of the shuttle and launch pad areas. Engineers also plan to review the flight software stored in the shuttle's mass memory units and display systems and load the Backup Flight System software into Discovery's onboard computers.

As launch preparations continue, NASA officials are keeping a close eye on tropical weather and its potential impact. Read our full story.

SUNDAY, OCTOBER 1, 2000

Read our full story on tonight's crew arrival with comments from the astronauts and a look ahead to the coming days before Thursday's blastoff of the 100th shuttle mission.

2310 GMT (7:10 p.m. EDT)

The six men and one woman who will fly aboard space shuttle Discovery this week have arrived at Kennedy Space Center for launch. The 100th shuttle mission remains scheduled for blastoff at Thursday night on the fifth U.S. mission to the international space station. Launch time is currently targeted for around 9:38 p.m. EDT (0138 GMT Friday).

Led by commander Brian Duffy, the STS-92 astronauts flew from their homes in Houston to Florida in T-38 jet trainers, touching down on KSC's three-mile-long runway just before sunset. The crew members include pilot Pam Melroy and mission specialists Leroy Chiao, Bill McArthur, Jeff Wisoff, Michael Lopez-Alegria and Koichi Wakata

Over the next several days the astronauts will undergo final medical exams, review flight plans, check out their spacesuits and have time to relax with family members. In addition, commander Duffy and pilot Melroy will practice landing approaches at KSC, which is where the 11-day mission is due to conclude.

At launch pad 39A, the flight readiness test of Discovery's three main engines is complete, the aft engine compartment has been closed and locked for flight and a confidence check was performed Saturday.

The three-day countdown is slated to begin in Firing Room 3 of the Launch Control Center on Tuesday at 12 a.m. EDT (0400 GMT). The entire launch team will report on station Monday night about a half-hour before the clocks start ticking.

2223 GMT (6:23 p.m. EDT)

Discovery's crew is currently expected to arrive at the Kennedy Space Center's landing strip at around 7 p.m. EDT (2300 GMT).

2111 GMT (5:11 p.m. EDT)

The crew of space shuttle Discovery are heading to the Kennedy Space Center after departing Ellington Field in Houston about 15-20 minutes ago, according to NASA spokesman Joel Wells. Their T-38 training jets could touchdown as early as 6:45 p.m. EDT if a refueling stop is not required. If they stop for fuel in St. Petersburg, Florida, it will delay their arrival by an hour.

FRIDAY, SEPTEMBER 29, 2000
1530 GMT (11:30 a.m. EDT)

To steer clear of a spent Russian rocket body, Russian flight controllers plan to fire the international space station's maneuvering jets today at 3:10 p.m. EDT to raise the apogee, or high point, of the lab's orbit by about two kilometers. The avoidance maneuver will change the station's orbit only slightly, but it will be enough to affect the shuttle Discovery's launch next week on a space station assembly mission by one second. Liftoff of the 100th shuttle mission now is targeted for 9:38:25 p.m. EDT, one second later than had been planned.

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

NASA officials on Thursday affirmed October 5 as the launch date for the 100th space shuttle mission -- an action-packed 11-day space station construction flight featuring four spacewalks.

While gathered at the Kennedy Space Center for the traditional Flight Readiness Review, senior managers concluded space shuttle Discovery, the seven-member astronaut crew and payloads were indeed ready for an on-time blastoff next week.

"The foundation for the International Space Station has been laid and this mission begins the true station build-up in orbit," Space Shuttle Program Manager Ron Dittemore said. "With multiple spacewalks planned and multiple components to attach, we're taking the level of complexity up a notch over the past few station construction flights."

The current launch time on October 5 is 9:38:24 p.m. EDT (0138:24 GMT on 6th). That time will be refined until the final hour of the countdown based upon radar tracking of the space station's orbit.

Activities are continuing at launch pad 39A to ready Discovery its mission. Earlier this week a liquid oxygen leak was found in the shuttle's plumbing and had to be repaired. Ordnance is now installed aboard the shuttle and efforts to close out the aft engine compartment are on-going.

The astronauts are due to arrive at Kennedy Space Center on Sunday night in advance of starting the countdown. The six men and one woman will fly from their home base at Johnson Space Center in Houston, Texas, to the Cape, with arrival expected around 7:30 p.m. EDT (2330 GMT). The crew is led by veteran shuttle commander Brian Duffy, with rookie pilot Pam Melroy, spacewalkers Leroy Chiao, Bill McArthur, Jeff Wisoff and Mike Lopez-Alegria, and robot arm operator Koichi Wakata of the Japanese Space Agency.

The launch countdown is scheduled to start at 12 a.m. EDT Tuesday leading to a Thursday night liftoff.

See our STS-92 Mission Report for complete coverage.

SUNDAY, SEPTEMBER 17, 2000
0945 GMT (5:45 a.m. EDT)

Hurricane Gordon won't force space shuttle Discovery off the launch pad today at Kennedy Space Center, NASA officials decided this hour. The storm's track no longer poses a serious threat to the Florida spaceport.

0500 GMT (1:00 a.m. EDT)

Kennedy Space Center remains on hurricane alert while preparations continue overnight for the potential of rolling space shuttle Discovery off its launch pad later this afternoon. However, such a move is becoming less likely given Hurricane Gordon's march northward in the Gulf of Mexico. The storm's predicted track is now expected to spare Florida's east coast of any significant wind.

Nonetheless, officials will meet at 5 a.m. EDT (0900 GMT) to decide whether to roll Discovery or not. The current plan, if implimented, would call for the giant rotating service structure to be retracted from around Discovery at 6 a.m. EDT and the trek back to the Vehicle Assembly Building start around 12 p.m. EDT.

SATURDAY, SEPTEMBER 16, 2000
2205 GMT (6:05 p.m. EDT)

The National Hurricane Center in Miami reports Gordon has strengthened, as expected, from a tropical storm to a hurricane. The system now has sustained winds of 75 mph with gusts to 90 mph.

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

NASA officials have ordered preparations to begin for rolling space shuttle Discovery off its launch pad and back to the safe confines of Kennedy Space Center's Vehicle Assembly Building on Sunday due to Tropical Storm Gordon.

The space center is currently under a Hurricane Condition 3, or HURCON, which serves as the second lowest alert. During this time, workers are sandbagging areas, securing outside structures, instrumentation and antennas and performing overall preparatory work.

As of 5 p.m. EDT, Gordon was continuing to gain strength in the Gulf of Mexico and could become a hurricane later tonight. The storm was packing winds of 70 mph with higher gusts. The forecast track indicates Gordon would make landfall somewhere along the Florida panhandle. Although that is far from Kennedy Space Center, the storm's massive size could still bring heavy rain and strong winds to the Cape, which is located on the east-central coast of Florida.

At launch pad 39A, technicians today installed the Z-1 space station truss into Discovery's 60-foot long payload bay, a job that was scheduled for early next week. But officials wanted the cargo inside Discovery so in case the shuttle has to leave the pad in seek of shelter, it can take the precision station section too.

A formal decision whether it will be necessary to roll Discovery back to the 52-story VAB is expected at 5 a.m. EDT (0900 GMT) Sunday. First motion would then occur sometime around 12 p.m. EDT (1600 GMT), taking around six hours to complete.

Shuttle Discovery was rolled to the seaside pad on Monday in advance of the scheduled October 5 launch to further the construction of the orbiting international space station. What impact to the planned launch date a possible rollback would have is not yet clear.