Spaceflight Now





BY JUSTIN RAY

Follow the preparations for space shuttle Discovery's test flight to the international space station.

MONDAY, JULY 3, 2006
2030 GMT (4:30 p.m. EDT)


Engineers are readying the shuttle Discovery for a third launch try Tuesday amid hurried work to assess the potential impact of missing foam insulation on the ship's external tank that broke off Sunday after a launch scrub. Read our full story.

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

The news conference here at Kennedy Space Center just wrapped up. The bottom line: managers will meet at 6:30 p.m. EDT tonight to decide if Discovery can launch tomorrow as-is and if photos (taken with powerful optics from 25 feet away) are enough to alleviate any worries about the remaining foam on the bracket.

If hands-on inspection of the bracket is ordered, launch would slip to Wednesday because of the time needed for establishing work platforms to access this region of the fuel tank.

Should any repair be necessary, it is not clear what that would do to the schedule.

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

Launch director Mike Leinbach says if a hands-on inspection of the foam on the bracket is required, liftoff of Discovery would have to slip to Wednesday to accommodate the work of getting an access platform set up in the area.

1749 GMT (1:49 p.m. EDT)

If a repair is deemed necessary, engineers would have to create a plan to do that work. Such a repair has not been performed on this area of the tank at the launch pad before. A team is looking at a scenario in case management orders a repair.

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

"No one has come to any conclusions," Shannon says about clearing this problem. Engineers are working this afternoon to determine whether the photographs taken of the shuttle after the foam loss is sufficient to clear any worries in launching Discovery as-is. The other option is putting hands on the bracket, but that would require putting up a platform to reach the area in question.

The 6:30 p.m. EDT meeting tonight by the Mission Management Team will decide which course of action to take and when launch can occur.

Commander Steve Lindsey participated in this morning's management team meeting. The piece of foam that fell off is now at crew quarters for the astronauts to see, Shannon said.

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

The weather outlook for tomorrow predicts a 40 percent chance of "no go" conditions. That percentage increased to 60 "no go" on Wednesday and Thursday.

1734 GMT (1:34 p.m. EDT)

Launch director Mike Leinbach says topping of the hydrogen storage tanks for the shuttle's electricity-producing fuel cells beneath the payload is underway right now. Those activities are proceeding on schedule to support another launch attempt tomorrow.

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

In the news conference now underway, Mission Management Team chairman John Shannon says it is believed ice in the articulating joint on the feedline bracket caused the foam to crack and fall off the external tank after yesterday's scrub. The bracket is one of several that holds the liquid oxygen feedline to the side of the fuel tank. The tank shrinks when loaded with supercold propellants during the countdown, then expands when the fuels are draining after a scrub, prompting the need for such a joint in the bracket. Ice created from yesterday's rainy weather was pinched in the joint during its movements when the tank expanded, causing the foam to pop off, engineers believe.

The foam shed is a three-inch piece, triangular in shape, and most importantly, less than half the weight NASA says could cause damage to the shuttle if it had come off during launch and hit Discovery.

No decisions have been made about tomorrow's launch opportunity. Servicing of Discovery's fuel cell storage tanks is underway to preserve that option. Another management team meeting is planned for this evening to determine whether launch can occur tomorrow or if more time will be needed to resolve the foam issue.

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

Photos of the cracked foam are available here.

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

The start time for the post-MMT meeting is now 1 p.m.

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

Briefing start time has moved to 12:30 p.m.

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

NASA is planning a news conference as early as 12 noon EDT today, following completion of the Mission Management Team meeting to brief reporters on the external tank foam crack and what the plan will be going forward.

The crack is located around a bracket near the top of the 17-inch diameter feedline pipe that routes the liquid oxygen down to the main engines on Discovery. The crack is four-to-five inches long and between an eighth and a quarter of an inch wide.

1315 GMT (9:15 a.m. EDT)

Engineers inspecting the shuttle Discovery's external tank following Sunday's launch scrub found a crack in the tank's foam insulation near a bracket holding a 17-inch oxygen feed line in place. Some engineers believe the crack must be repaired but senior managers say a variety of options are on the table, from fly as is to making repairs. Read our full story.

SUNDAY, JULY 2, 2006
2050 GMT (4:50 p.m. EDT)


The latest episode of Spaceflight Now's free Mission Report Minute video podcast is now available on iTunes. You can download the bulletin here.

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

NASA launch director Mike Leinbach says the schedule to get the fuel cell servicing performed and prepare for a fresh countdown on Tuesday will be very tight. The plan includes rolling the rotating service structure back around Discovery, opening up the ship's midbody access ports and connecting the fuel cell reactant umbilicals to top off the hydrogen tanks.

The fuel cells combine liquid hydrogen and liquid oxygen to generate electricity for the shuttle's systems during the mission and produce drinking water for the astronauts as a byproduct.

By replenlishing the hydrogen tanks, NASA will have back-to-back launch opportunities available on Tuesday and Wednesday, while protecting the option of extending Discovery's mission an extra day to insert a third spacewalk into the flight.

The oxygen supply is sufficient and doesn't need replenishment.

The supercold reactants naturally boil off and need topping if launches are delayed.

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

For a second straight day, the shuttle Discovery was grounded because of cloud cover over the Kennedy Space Center today, delaying a long-awaited mission to service and resupply the international space station. Launch was rescheduled for around 2:38 p.m. EDT on the July Fourth holiday. Read our full story.

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

NASA is planning a post-scrub news conference at 3 p.m. EDT.

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

And now the AstroVan is driving away from pad 39B for return to crew quarters where the astronauts will wait out the 48 hours until the next countdown.

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

Discovery's crew has exited the shuttle following today's scrub.

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

"I'll talk to you again on the Fourth," Discovery commander Steve Lindsey radioed orbiter test conductor Rudy Tench as he prepared to unstrap and leave the shuttle.

"Copy that, sir, looking forward to it," Tench replied.

"Me too. It'll be a good day to launch."

Tuesday's countdown will be the first time a shuttle has attempted to launch on Independence Day.

1734 GMT (1:34 p.m. EDT)

All five mission specialists have egressed the orbiter.

1729 GMT (1:29 p.m. EDT)

The AstroVan has been dispatched back to the launch pad as the astronauts begin climbing out of their ship.

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

SCRUB! The weather has won for the second day in a row. Launch director Mike Leinbach just decided to stop the countdown for liftoff today due to the miserable weather conditions here at Kennedy Space Center.

Management has decided to replenish the hydrogen supply in the shuttle's electricity-producing fuel cells and make the next launch attempt on Tuesday at 2:38 p.m. EDT (1838 GMT).

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

The weather forecast for tomorrow predicts a 60 percent chance of unacceptable conditions at the 3:00 p.m. EDT (1900 GMT) launch time. The forecast for Tuesday's 2:38 p.m. EDT (1838 GMT) launch time is 40 percent "no go."

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

The launch team is halting work, pending word from management whether the countdown will continue today. The weather situation looks very bleak.

1705 GMT (1:05 p.m. EDT)

We're awaiting an announcement from the launch director to the crew.

1701 GMT (1:01 p.m. EDT)

T-minus 90 minutes and counting. Countdown clocks continue to roll to T-minus 20 minutes where the next hold is planned.

At this point in the count, the ground launch sequencer software that will control the final nine minutes of the countdown has been initialized. Also, the solid rocket boosters' gas generator heaters in the hydraulic power units are turned on, the aft skirt gaseous nitrogen purge is starting and the rate gyro assemblies (RGAs) are being activated. The RGAs are used by the orbiter's navigation system to determine rates of motion of the boosters during the first stage of flight.

1659 GMT (12:59 p.m. EDT)

A series routine communications checks between the Discovery crew and various audio channels is underway.

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

The seventh and final member of Discovery's crew is now inside the shuttle. Mission specialist No. 2, Lisa Nowak, is heading to the flight deck's center seat.

Nowak is a spaceflight rookie. Read her biography here.

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

The skies have become very menacing here at Kennedy Space Center. Dark gray walls of clouds surround the launch base now.

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

Astronaut Piers Sellers, mission specialist No. 4, has crawled through the hatch. He will take the middeck's center seat.

Sellers flew a construction mission to the space station in 2002. Read his biography here.

1634 GMT (12:34 p.m. EDT)

Discovery's mission specialist No. 1, Mike Fossum, has climbed to the flight deck aft-right seat.

Fossum will be making his first flight into space on STS-121. Read his biography here.

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

Mission specialist No. 3 Stephanie Wilson is aboard Discovery now. She is positioned closest to the hatch in the left seat on the middeck.

Wilson is one of the spaceflight rookies on the mission. Read her biography here.

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

Pilot Mark Kelly is the next crewmember to enter the shuttle. He is making his way to the flight deck's front-right seat.

Kelly has one previous shuttle flight to his credit in 2001. Read his biography here.

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

Now climbing through the hatch is mission specialist No. 5, Thomas Reiter. He is assigned the right seat on the middeck.

The German-born Reiter is a European Space Agency astronaut. He will stay on the space station after Discovery departs, beginning a long-duration Expedition mission. Read his biography here.

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

Weather remains "no go" at this time due to violations of the lightning, electrical charge potential, cumulus cloud and anvil cloud rules.

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

Commander Steve Lindsey is the first astronaut to enter the shuttle. He is taking he forward-left seat on the flight deck.

Lindsey has flown in space on three earlier missions, including serving as the pilot on a 1997 science mission and John Glenn's 1998 shuttle flight. Then he served as commander on the mission to deliver the Quest airlock to the space station in 2001. Read his biography here.

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

Discovery's seven astronauts have arrived at the launch pad for boarding their space shuttle.

1549 GMT (11:49 a.m. EDT)

The AstroVan convoy just made its brief stop at the Launch Control Center to allow the management riding with the crew to jump out and head over to the Firing Room.

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

The astronauts are on their way to launch pad 39B. The crew just walked out of the Operations and Checkout Building along with some NASA managers and weather reconnaissance pilot Mike Bloomfield to board the AstroVan with gun-carrying KSC security personnel looking on.

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

T-minus 3 hours and counting. The clocks have resumed ticking after a three-hour planned hold. The next pause in the count is scheduled at T-minus 20 minutes.

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

The crew is finishing up with the suiting activities. They'll be departing quarters within the hour.

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

The launch weather rules being violated currently are lightning, electrical charge potential, cumulus clouds and anvil clouds.

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

Following yesterday's scrub, we have updated the ascent data page to reflect today's launch time.

1442 GMT (10:42 a.m. EDT)

Now that the shower has passed through, the skies have cleared overhead and the morning has become extremely hot and humid. But some of the weather rules remain "no go" due to the clouds to the east.

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

The astronauts are getting into their cumbersome launch and entry spacesuits. They plan to head for the pad in about an hour.

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

The flight through precipitation violation has been lifted.

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

The cloud ceiling and disturbed weather rules are back in "go" status.

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

As this area of weather moves over the launch site, the launch rules being violated are lightning, field mills, disturbed weather, cumulus clouds, anvil clouds, thick clouds, flight through precipitation and the cloud ceiling.

The only rules not broken at the moment are thunderstorm debris clouds, smoke plumes, launch wind and the temperature.

1354 GMT (9:54 a.m. EDT)

The rain is coming down here at the KSC Press Site.

1347 GMT (9:47 a.m. EDT)

The astronauts have entered the dining room for a pre-launch snack before they don the spacesuits and head for the pad this morning.

1329 GMT (9:29 a.m. EDT)

The field mills, which comprise a network of detectors around the Cape to measure the electrical charge in the air, is measuring "no go" conditions now.

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

Thunder now rumbling across the Kennedy Space Center -- and not of the launch kind. A storm that has brought heavy rain across Brevard County has moved northward to KSC.

1311 GMT (9:11 a.m. EDT)

And now the anvil cloud rule is "no go" again, too.

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

Latest check of the weather shows the lightning, cumulus cloud and thick cloud rules are being violated at this time.

1233 GMT (8:33 a.m. EDT)

For those keeping score at home, fueling officially began at 5:28 a.m. and was completed at 8:23 a.m.

1231 GMT (8:31 a.m. EDT)

T-minus 3 hours and holding. The count has just gone into a planned 3-hour built-in hold.

Weather conditions are currently "no go" due to showers coming ashore from the Atlantic Ocean, violating the anvil and lightning rules. "And so it begins," NASA spokesman George Diller says. The outlook for the 3:26 p.m. EDT launch time calls for a 70 percent chance of "no go" weather.

1229 GMT (8:29 a.m. EDT)

The Orbiter Closeout Crew and the Final Inspection Team have been cleared for travels to pad 39B to begin their launch morning jobs. The closeout crew will be readying the Discovery's cockpit for astronaut boarding later today; the inspection team will be examining the exterior of the shuttle vehicle for ice now that fueling is finished.

1224 GMT (8:24 a.m. EDT)

Liquid oxygen has gone into stable replenishment, joining liquid hydrogen that entered this mode a little while ago. So filling of Discovery's external has been completed.

1205 GMT (8:05 a.m. EDT)

The liquid hydrogen fuel tank has been filled up and the liquid oxygen is nearing completion of the fast-fill mode for today's launch opportunity of Discovery.

The launch weather team reports an area of showers is approaching the Cape and rain is expected at pad 39B in about 45 minutes.

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

Good morning from a cloudy Kennedy Space Center where fueling of space shuttle Discovery's external tank is still going smoothly. The three-hour tank filling process is about two-thirds complete now, and no troubles have been reported thus far.

The countdown is marching toward a launch at 3:26 p.m. EDT today. However, the weather forecast is not good. Meteorologists are saying there is a 70 percent chance that thunderstorms and anvil clouds will break the launch rules this afternoon.

The outlook is 60 percent "no go" for Monday and 40 percent "no go" on Tuesday.

If the weather forces another scrub today, the Mission Management Team would meet to decide whether to make a rare third consecutive launch attempt or give everyone a day to rest and try again Tuesday.

If Discovery is not off the ground by Wednesday, the onboard fuel cell hydrogen reactant supply used to generate electricity in space would need to be replenished, requiring a further delay.

1009 GMT (6:09 a.m. EDT)

Both liquid hydrogen and liquid oxygen fueling operations have progressed through the chilldown thermal conditioning and into the slow-fill mode. Once each tank is loaded slightly, the pumping rate increases to the fast-fill mode.

And the engine cutoff, or ECO, sensors in both tanks are working normally this morning.

We'll resume our live updates from Kennedy Space Center around 7:30 a.m.

0930 GMT (5:30 a.m. EDT)

Re-fueling of space shuttle Discovery with the half-million gallons of cryogenic rocket propellants began at 5:28 a.m. EDT this morning. It will take three hours to fill the ship's external fuel tank.

The weather forecast for today's planned 3:26 p.m. EDT launch indicates only a 30 percent chance of acceptable conditions. Forecasters are giving the bleak outlook due to the expected development of thunderstorms across Florida during the day.

No technical problems are being reported in the countdown and activities are proceeding for this second attempt to launch Discovery on mission STS-121.

SATURDAY, JULY 1, 2006

Launch of the shuttle Discovery on a long-awaited space station servicing and resupply mission was called off today because of cloud cover and the threat of lightning over the Kennedy Space Center. Read our full story.

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

All seven astronauts have egressed the orbiter. They will take the AstroVan back to crew quarters to get dinner and some rest before tomorrow's early morning wakeup call for the second countdown.

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

Thomas Reiter and Piers Sellers have climbed from Discovery.

2035 GMT (4:35 p.m. EDT)

The hatch is now open.

2030 GMT (4:30 p.m. EDT)

The Orbiter Closeout Crew has returned to the pad. They have been given a "go" to open Discovery's hatch and assist the astronauts out of the shuttle.

1953 GMT (3:53 p.m. EDT)

Draining of the cryogenic propellants from the external tank is underway following the scrub.

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

SCRUB. Launch director Mike Leinbach has called a scrub for today's countdown. Weather conditions at the Kennedy Space Center are unacceptable for liftoff during the narrow launch window this afternoon, forcing a 24-hour postponement. Sunday's target launch time is 3:26 p.m. EDT.

"It's not a good day to launch," ascent flight director Steve Stich radioed from Mission Control-Houston.

1939 GMT (3:39 p.m. EDT)

The countdown has remained in the T-minus 9 minute hold. This extended hold can last 5 minutes, essentially using up the available launch window while waiting for the weather to clear.

"If luck is on our side, we'll go. If not, we'll try again tomorrow," Leinbach says.

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

The Range is now reporting there's a boat in the restricted in the waters off the coast that must be cleared before launch.

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

The plan will be extend this hold a few more minutes to wait for the weather to miraculously improve. The launch window closes at 3:53:14 p.m.

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

NASA launch director Mike Leinbach is conducting his poll.

1934 GMT (3:34 p.m. EDT)

The final readiness poll of the team by NASA test director has been completed. Weather is "no go."

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

The Mission Management Team has been polled by chairman John Shannon for readiness to proceed with the countdown. No constraints were reported, however weather was not part of that poll.

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

"I don't hold a lot of hope," ascent flight director Steve Stich says about the weather due to the close proximity of thunderstorm anvil clouds.

1925 GMT (3:25 p.m. EDT)

Weather remains observed and forecast "no go" for launch. The situation will be monitored during the rest of this planned hold.

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

Ascent flight director Steve Stich in Houston reports that weather at the abort landing site here in Florida is the only concern for the Mission Control.

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

Everything from a technical standpoint is ready for launch. But NASA launch director Mike Leinbach says the weather team is tracking the anvil clouds from a thunderstorm about 30 miles west of the pad that prevent liftoff today.

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

Weather is still "no go."

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

Weather assessments continue. The western sky is a wall of clouds. Yet it is sunny over the launch pad and out to sea. This hold is scheduled to end at 3:39:41 p.m. for an on-time launch today at 3:48:41 p.m.

Liftoff could occur as late as 3:53:14 p.m. or else Discovery must wait until tomorrow. (Note the window close time has been adjusted a few seconds from the earlier update).

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

T-minus 9 minutes and holding. Countdown clocks have gone into the planned 45-minute built-in hold. Today's launch remains set for 3:48:41 p.m. EDT. There are no significant technical problems being reported, but the weather remains a real concern. Anvil clouds are violating the launch rules right now.

1853 GMT (2:53 p.m. EDT)

The Orbiter Closeout Crew is departing the pad.

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

The Main Propulsion System helium system is being reconfigured by pilot Mark Kelly. Soon the gaseous nitrogen purge to the aft skirts of the solid rocket boosters will be started.

1848 GMT (2:48 p.m. EDT)

Pilot Mark Kelly is configuring the displays inside Discovery's cockpit for launch while commander Steve Lindsey enables the abort steering instrumentation. And Mission Control in Houston is loading Discovery's onboard computers with the proper guidance parameters based on the projected launch time.

1848 GMT (2:48 p.m. EDT)

T-minus 15 minutes. Now one hour away from launch of Discovery, if the weather clears.

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

T-minus 20 minutes and counting. The countdown has resumed after a 10-minute hold. 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 adjusted to synch up with today's preferred launch time of 3:48:41 p.m.

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.

1842 GMT (2:42 p.m. EDT)

Mission Management Team chairman John Shannon has ruled that the failed heater on one of Discovery's vernier thruster is not a constraint to flight.

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

Over at the Shuttle Landing Facility, astronaut Mike Bloomfield is shooting approaches to the runway in the Shuttle Training Aircraft. He is evaluating the weather conditions in the event Discovery is forced to perform a Return to Launch Site abort shortly after liftoff.

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

A good seal on Discovery's crew hatch is confirmed. The cabin pressurized for flight, and the pressure checks have been completed.

1833 GMT (2:33 p.m. EDT)

T-minus 20 minutes and holding. The countdown has paused for a 10-minute built-in hold. Launch remains scheduled for 3:48:41 p.m. EDT, if the weather improves. Clouds over the Cape remain unacceptable for launch.

During this built-in hold, all computer programs in Firing Room 4 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.

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

Commander Steve Lindsey is pressurizing the gaseous nitrogen system for Discovery's Orbital Maneuvering System engines, and pilot Mark Kelly is activating the gaseous nitrogen supply for the orbiter's Auxiliary Power Units' water spray boilers.

1826 GMT (2:26 p.m. EDT)

The shuttle's backup flight control system (BFS) computer has been configured. It would be used today in the event of emergency landing.

Also, the primary avionics software system (PASS) has transferred to Discovery's BFS computer so both systems can be synched with the same data. In case of a PASS computer system failure, the BFS computer will take over control of the shuttle vehicle during flight.

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

The ground pyro initiator controllers (PICs) are scheduled to be powered up around this time in the countdown. They are used to fire the solid rocket hold-down posts, liquid oxygen and liquid hydrogen tail service mast and external tank vent arm system pyros at liftoff and the space shuttle main engine hydrogen gas burn system prior to engine ignition.

The shuttle's two Master Events Controllers are being tested. They relay the commands from the shuttle's computers to ignite, and then separate the boosters and external tank during launch.

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

Weather remains "no go" right now for anvil clouds.

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

The Ground Launch Sequencer mainline activation has been completed. The GLS is the master computer program that controls the final 9 minutes of the countdown, monitoring as many as a 1,000 different systems and measurements to ensure they do not fall out of pre-determined limits.

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

With Discovery's crew module hatch now shut, the Orbiter Closeout Crew is working to latch it. Pressure and leak checks will be performed shortly to ensure a good seal on the hatch for today's launch.

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

The pre-flight alignment of Discovery's Inertial Measurement Units is underway 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 will soon shift 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.

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

The "go" has been given to close the shuttle's crew compartment hatch. The hatch is swinging shut now.

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

The official target launch time remains unchanged according to the latest update on the space station's orbit. The launch window opens at 3:44:40 p.m., with the desired liftoff time of 3:48:41 p.m.. The window closes at 3:53:02 p.m.

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

The Orbiter Closeout Crew has removed all non-flight items from Discovery in advance of closing the hatch for flight.

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

A series routine communications checks between the Discovery crew and various audio channels is underway.

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

Weather continues to be the primary concern for launch today. Conditions are "no go" at the present time due to electrically charged anvil clouds at the launch site. Forecasters now say there is a 60 percent chance of weather prohibiting launch today. Similar odds are being giving for Sunday. Monday is even worse with a 70 percent chance of unacceptable conditions.

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

The seventh and final member of Discovery's crew is now inside the shuttle. Mission specialist No. 2, Lisa Nowak, is heading to the flight deck's center seat.

Nowak is a spaceflight rookie. Read her biography here.

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

Bill Harwood of CBS News reports that although NASA's mission management team has not yet weighed in on the vernier thruster heater issue, sources say the engineering community and the flight control team favor pressing ahead with launch.

The shuttle is equipped with six so-called vernier jets, two forward and four aft, that are used to adjust the orbiter's orientation in space. Temperature readings from thruster L5L this morning indicated its heater was not operating.

The thruster must be at 90 degrees to operate but mission managers believe the shuttle can safely carry out all its planned maneuvers and stabilization work using five vernier jets if L5L cannot be warmed up enough to fire. That includes stabilization for critical heat-shield inspections planned for Sunday and orientation control when the shuttle is docked with the international space station.

The shuttle can fly its normal mission and perform all planned maneuvers with five operational vernier thrusters and if worse came to worse, the crew could use more powerful primary thrusters at the expense of higher-than-normal fuel useage.

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

T-minus 90 minutes and counting. Countdown clocks continue to tick down to T-minus 20 minutes where the next hold is planned. Countdown activities remain on track for liftoff at 3:48:41 p.m.

At this point in the count, the ground launch sequencer software that will control the final nine minutes of the countdown has been initialized. Also, the solid rocket boosters' gas generator heaters in the hydraulic power units are turned on, the aft skirt gaseous nitrogen purge is starting and the rate gyro assemblies (RGAs) are being activated. The RGAs are used by the orbiter's navigation system to determine rates of motion of the boosters during the first stage of flight.

1708 GMT (1:08 p.m. EDT)

Discovery's mission specialist No. 1, Mike Fossum, has climbed to the flight deck aft-right seat.

Fossum will be making his first flight into space on STS-121. Read his biography here.

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

Astronaut Piers Sellers, mission specialist No. 4, has crawled through the hatch. He will take the middeck's center seat.

Sellers flew a construction mission to the space station in 2002. Read his biography here.

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

Weather conditions have gone red or "no go" again due to clouds in the area. There's also a concern about lightning now.

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

Mission specialist No. 3 Stephanie Wilson is aboard Discovery now. She is positioned closest to the hatch in the left seat on the middeck.

Wilson is one of the spaceflight rookies on the mission. Read her biography here.

1648:41 GMT (12:48:41 p.m. EDT)

Now three hours from launch.

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

Pilot Mark Kelly is the next crewmember to enter the shuttle. He is making his way to the flight deck's front-right seat.

Kelly has one previous shuttle flight to his credit in 2001. Read his biography here.

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

Now climbing through the hatch is mission specialist No. 5, Thomas Reiter. He is assigned the right seat on the middeck.

The German-born Reiter is a European Space Agency astronaut. He will stay on the space station after Discovery departs, beginning a long-duration Expedition mission. Read his biography here.

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

As shuttle commander, Lindsey is the first astronaut to board the shuttle. He is taking he forward-left seat on the flight deck.

Lindsey has flown in space on three earlier missions, including serving as the pilot on a 1997 science mission and John Glenn's 1998 shuttle flight. Then he served as commander on the mission to deliver the Quest airlock to the space station in 2001. Read his biography here.

1626 GMT (12:26 p.m. EDT)

Commander Steve Lindsey has made his way across the catwalk-like Orbiter Access Arm to the White Room positioned against the side of Discovery. The closeout crew is helping him don other survival gear.

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

The Discovery astronauts have reached the 195-foot level of the tower.

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

Discovery's crew arrived at launch pad 39B at 12:18 p.m. The AstroVan just came to a stop on the pad surface near the Fixed Service Structure tower elevator that will take the seven-person crew to the 195-foot level to begin boarding the shuttle this afternoon.

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

The local weather conditions are back "go" again. Some clouds were violating the launch rules a short time ago.

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

The AstroVan is passing the 52-story Vehicle Assembly Building where Discovery was attached to its external tank and solid rocket boosters and the adjacent Launch Control Center. The Press Site is located across the street, and reporters have run outdoors to watch at the passing convoy. This is a launch day tradition to say farewell and good luck to the astronaut crews.

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

Commander Steve Lindsey and his six fellow crewmates have emerged from the Kennedy Space Center crew quarters to board the AstroVan for the 7-mile ride from the Industrial Area to launch pad 39B on the edge of the Atlantic Ocean.

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

Shuttle launch weather officer Kathy Winter reports that current observed conditions at Kennedy Space Center are "no go" due to cumulus and anvil clouds overhead. The weather will be closely monitored throughout the afternoon as conditions evolve and change.

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

T-minus 3 hours and counting. The countdown has resumed on schedule from this planned three-hour built-in hold. Clocks will now tick down to T-minus 20 minutes when the next hold is planned. A final hold is scheduled at the T-minus 9 minute mark to synch up with the 3:48:41 p.m. EDT launch time.

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

All seven astronauts have donned their day-glow orange launch and entry partial pressure spacesuits. After final adjustments and pressure checks, the crew plans to depart the suit-up room and take the elevator down to the ground level of the Operations and Checkout Building to board the AstroVan for the trip to launch pad 39B. We expect to see the crew walk out of the O&C Building around 11:58 a.m. EDT.

1453 GMT (10:53 a.m. EDT)

The countdown is still holding at the T-minus 3 hour mark. Clocks are slated to resume ticking in 60 minutes.

The analysis and debate about the faulty heater on one of Discovery's vernier steering thrusters continues. That heater is not working, which makes the maneuvering jet considered failed for the mission. Although there are other thrusters that can compensate for the loss of the L5L jet, managers must decide if they want to launch knowing some of the redundancy is gone.

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

The inspection team is responsible for checking Discovery and the launch pad one last time prior to liftoff. The team is comprised of engineers and safety officials from NASA, United Space Alliance and tank-builder Lockheed Martin. At the conclusion of their two-hour tour-of-duty, the team will have walked up and down the entire fixed service structure and mobile launcher platform.

The team is on the lookout for any abnormal ice or frost build-up on the vehicle and integrity of the external tank foam insulation.

The team uses a portable infrared scanner that gathers temperature measurements on the surface area of the shuttle and can spot leaks. The scanner will be used to obtain temperature data on the external tank, solid rocket boosters, space shuttle orbiter, main engines and launch pad structures. The scanner can also spot leaks of the cryogenic propellants, and due to its ability to detect distinct temperature differences, can spot any dangerous hydrogen fuel that is burning. The team member also is responsible for photo documentation.

The team wears the highly visible day-glow orange coveralls that are anti-static and flame resistant. Each member also has a self-contained emergency breathing unit that holds about 10 minutes of air.

No significant problems or concerns have been reported by the inspection team so far.

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

Dressed in red shirts featuring the STS-121 mission emblem, Discovery's seven astronauts are gathered around the dining room table for a pre-launch snack. They were awakened at 5:15 a.m. EDT to begin the launch day activities at Kennedy Space Center.

After a bite to eat, commander Steve Lindsey, pilot Mark Kelly and flight engineer Lisa Nowak will receive a briefing on the weather forecast for KSC and abort landing sites in California, New Mexico, Spain and France. Then they will join their crewmates in the suit-up to don the launch and entry spacesuits in preparation for heading to pad 39B.

1401 GMT (10:01 a.m. EDT)

NASA spokesman Bruce Buckingham says mission managers have "high hopes" the vernier thruster problem on Discovery's left-hand orbital maneuvering system pod can fly as-is and the situation be managed in space without impact to the flight. A heater on the L5L thruster failed just after being activited this morning.

1353 GMT (9:53 a.m. EDT)

Now one hour into this planned hold in the countdown at the T-minus 3 hour mark. In about 15 minutes, the astronauts will gather in the dining room at crew quarters for the traditional launch day photo opportunity while seated around the mission cake.

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

The Final Inspection Team is beginning its two-hour observations of the shuttle vehicle.

1317 GMT (9:17 a.m. EDT)

The Orbiter Closeout Crew has arrived in the White Room on the end of the Orbiter Access Arm catwalk that runs from the launch pad tower to Discovery's crew module. They will make final preparations to ready Discovery for the astronaut's arrival about three hours from now.

1254 GMT (8:54 a.m. EDT)

Filling of Discovery's external fuel tank was called complete at 8:53 a.m. EDT. The tank has been pumped full with 528,000 gallons of supercold liquid oxygen and liquid hydrogen.

But given the cryogenic nature of the oxidizer and propellant, the supplies naturally boil away. So the tanks are continuously topped off until the final minutes of the countdown in a procedure called "stable replenishment."

With the hazardous tanking operation completed, the Orbiter Closeout Crew and Final Inspection Team will be heading to the pad to perform their jobs. The closeout crew will ready Discovery's crew module for the astronauts' ingress in a couple of hours; and the inspection team will give the entire vehicle a check for any ice formation following fueling.

1253 GMT (8:53 a.m. EDT)

T-minus 3 hours and holding. Countdown clocks have entered a planned three-hour built-in hold in advance of today's launch of space shuttle Discovery. This is a standard hold in every shuttle countdown. However, NASA has extended it from the usual two hours to three hours to give the Final Inspection Team more time to complete their ice and debris checks of the shuttle after fueling. The team will be sent to pad 39B to begin the inspections once fueling of Discovery is completed.

Also awaiting dispatch to the pad is the Orbiter Closeout Crew, which is the team that will assist the astronauts during boarding.

1223 GMT (8:23 a.m. EDT)

The liquid hydrogen system has entered into replenish mode to keep Discovery's tank topped off through the rest of the count. Liquid oxygen tank filling has another 20 or minutes left to go.

1217 GMT (8:17 a.m. EDT)

Filling of the liquid hydrogen tank has reached the 98 percent mark. Topping of the tank is beginning. The liquid oxygen loading is continuing.

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

Good morning from sunny Kennedy Space Center where we are beginning our complete live reports throughout the mission of space shuttle Discovery.

Fueling is entering the final hour of the three-hour process. No leaks or concentrations of liquid oxygen or liquid hydrogen have been detected in the shuttle's aft compartment. And the engine cutoff sensors, which were a source of trouble during the last mission, are functioning fine today.

Officials continue to discuss the heater problem on one of Discovery's vernier engine thrusters. The level of significance for this issue is unclear right now, if the problem cannot be resolved during the count.

1049 GMT (6:49 a.m. EDT)

There are actually two tanks inside the shuttle's orange bullet-shaped tank. The liquid oxygen tank fills the top third of the external tank. It will be filled with 143,000 gallons of liquid oxygen chilled to minus 298 degrees Fahrenheit (minus 183 degrees Celsius). The liquid hydrogen tank is contained in the bottom two-thirds of the external tank. It holds 385,000 gallons of liquid hydrogen chilled to minus 423 degrees Fahrenheit (minus 253 degrees Celsius).

The cryogenics are pumped from storage spheres at the pad, through feed lines to the mobile launcher platform, into Discovery's aft compartment and finally into the external fuel tank.

Fueling operations are progessing smoothly this morning. The liquid hydrogen tank is about a quarter full and the liquid oxygen tank is 20 percent full.

The loading began in slow-fill mode for each tank. That process continued until the tanks were five percent full, then the fast-fill took over.

1047 GMT (6:47 a.m. EDT)

The engine cutoff sensors in the external tank are working normally. The hydrogen sensors were replaced in the Vehicle Assembly Building.

Meanwhile, technicians are examining a vernier engine heater issue, but that's not something of major concern, a NASA spokesman says.

1001 GMT (6:01 a.m. EDT)

The chilldown thermal conditioning of the propellant lines and Discovery's internal plumbing is underway. The chilldown preps the systems for the shock from the super-cold cryogenic liquid oxygen and liquid hydrogen fuels that will be pumped into the external tank this morning.

0959 GMT (5:59 a.m. EDT)

Fueling operations have begun! The launch team is beginning the steps in the procedures to start fueling.

0953 GMT (5:53 a.m. EDT)

T-minus 6 hours and counting. The countdown has resumed from the two-hour built-in hold.

0946 GMT (5:46 a.m. EDT)

The start of fueling is expected to begin in the next 15 minutes. Countdown clocks are holding as scheduled at the T-minus 6 hour mark. The count will resume at 5:53 a.m. EDT and head to the T-minus 3 hour mark where a three-hour hold is planned.

0931 GMT (5:31 a.m. EDT)

The mission management team has given a "go" to begin fueling shuttle Discovery this morning as planned.

Managers convened their "pre-tanking meeting" at Kennedy Space Center around 4:45 a.m. to review the progress of work at launch pad 39B and the weather before giving engineers approval to begin fueling Discovery. The loading of the shuttle's external fuel tank will take nearly three hours to complete.

There are no significant technical issues being worked by the launch team and the weather forecast has improved a bit. Meteorologists now expect a 60 percent chance of acceptable conditions at launch time today.

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

The cocoon-like rotating service structure peeled away from space shuttle Discovery this evening, revealing the spaceplane on launch pad 39B as technicians made final preparations to begin pumping a half-million gallons of supercold rocket fuel into the external tank just before 6 a.m. Liftoff is set for 3:48:41 p.m. EDT.

Discovery's astronauts are asleep right now. They'll be awakened at 5:15 a.m. to begin launch morning activities. Departure from the crew quarters for the ride to the launch pad is scheduled for 11:58 a.m.

We will provide live play-by-play reports on the countdown starting at about 5:30 a.m. in advance of fueling operations commencing.

A detailed look at the countdown is available here.

For a look at the launch events, see our timeline here.

2348 GMT (7:48 p.m. EDT Fri.)

The rotating service structure just started rolling back from space shuttle Discovery to expose the orbiter for the remainder of the countdown to tomorrow's launch.

The mobile structure provides the primary access and weather protection for Discovery during its stay on the launch pad. The RSS was used for installing the payloads into the shuttle and feeding the reactants into the ship's three electricity-generating fuel cells, too.

Measuring 102 feet long, 50 feet wide and 130 feet high, the structure swings 120 degrees via hinges from the fixed launch pad tower.

Once the RSS arrives in its parked position for launch, teams at pad 39B will spend the next several hours performing final work to secure the complex for liftoff. The pad will be cleared of all personnel before operations begin to load Discovery's external fuel tank with a half-million gallons of cryogenic propellants shortly before 6 a.m.

FRIDAY, JUNE 30, 2006

The shuttle Discovery's countdown is on track today for a launch attempt Saturday at 3:49 p.m., weather permitting. Forecasters continue to predict a 60 percent chance of unacceptable weather Saturday, Sunday and Monday due to electrically charged anvil clouds within 23 miles of the launch area and a possibility of showers.

Thunderstorms Thursday afternoon delayed work to load Discovery's internal tanks with liquid oxygen and hydrogen for the ship's electricity producing fuel cells. But the launch team had eight hours of built-in hold time Thursday to make up for any delays and by this morning, the countdown was back on track.

Based on the actual load, flight controllers now believe Discovery may have enough power generation capability to permit a one-day mission extension - and a third spacewalk to test wing leading edge repair techniques - even if launch is delayed to July 4. Based on earlier predictions, July 3 appeared to be the cutoff for a mission extension, barring extensive crew conservation procedures. In any case, no decision will be made on a possible mission extension until well into Discovery's mission.

Read our full story.

THURSDAY, JUNE 29, 2006

Afternoon thunderstorms delayed work to load the shuttle Discovery's fuel cell system today, but engineers expect to make up the lost time later this evening and mission managers said the orbiter will be ready for launch Saturday, weather permitting, on the second post-Columbia mission.

"I'm very happy to report that we just had our launch-minus two-day mission management team review and other than some questionable weather, we have no constraints to launch," said John Shannon, chairman of the mission management team. "It's been a long year, with a lot of hard work by all of the team members to get to this point and I just want to say I'm extremely proud of the team and we are ready to go for Saturday and do what NASA does best."

Read our full story.

2005 GMT (4:05 p.m. EDT)

The threat of lightning has delayed this afternoon's loading of the space shuttle fuel cells with liquid hydrogen and liquid oxygen reactants, NASA launch director Mike Leinbach says. Once the lightning potential passes, the storage tanks located beneath the payload bay of Discovery will be filled with the cryogenics. Leinbach says there is plenty of margin in the countdown to deal with this weather delay.

Meanwhile, the Mission Management Team just completed the Launch Minus 2 Day readiness review. There are no constraints to launch and liftoff remains set for Saturday.

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

Discovery's three-day launch countdown is progressing smoothly at Kennedy Space Center.

Clocks entered a planned four-hour built-in hold at T-27 hours at 9 a.m. EDT this morning. When the count resumes, work to load the shuttle's three electricity-producing fuel cells with liquid hydrogen and liquid oxygen reactants will begin.

"Right now, we're where we want to be, which is on schedule and tracking no significant issues," Pete Nickolenko, NASA test director, said this morning.

"All of our systems are in great shape, we're on schedule, have no issues and our teams are ready and looking forward to launch on Saturday."

There has been no change in the weather outlook. Forecasters are still predicting a 40 percent chance of acceptable conditions for liftoff.

WEDNESDAY, JUNE 28, 2006

The shuttle Discovery is in good shape and on track for launch Saturday, but forecasters are predicting a 60 percent chance of electrically charged anvil clouds and afternoon showers Saturday, Sunday and Monday that would prevent takeoff. Read our full story.

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TUESDAY, JUNE 27, 2006

The seven space shuttle Discovery astronauts flew to Kennedy Space Center on Tuesday from their training base in Houston in preparation for Saturday's planned liftoff. The launch countdown remains set to begin ticking at 5 p.m. on Wednesday. Read our full story.

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1441 GMT (10:41 a.m. EDT)

"Great to be here," commander Steve Lindsey says. "Hopefully we'll be airborne on Saturday."

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

And Discovery's seventh astronaut, Piers Sellers, has landed at Kennedy Space Center aboard T-38 no. 914 piloted by astronaut Randy Bresnik.

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

T-38 no. 910 with pilot Mark Kelly and Stephanie Wilson has arrived.

1423 GMT (10:23 a.m. EDT)

Center director Jim Kennedy, launch director Mike Leinbach and astronaut Jerry Ross are at the ramp to welcome the arriving Discovery crewmembers this morning.

1418 GMT (10:18 a.m. EDT)

Mission specialist Mike Fossum aboard T-38 no. 960 has just touched down. Piloting the aircraft is astronaut Steve Frick.

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

The T-38 no. 906 piloted by Discovery commander Steve Lindsey with space station flight engineer Thomas Reiter in the back has just pulled to the parking ramp at the Shuttle Landing Facility.

1405 GMT (10:05 a.m. EDT)

Discovery mission specialist Lisa Nowak is the first of the astronauts to arrive at Kennedy Space Center. Riding in the back seat of NASA's T-38 tailnumber 912, she was flown to KSC by astronaut Jim Halsell.

1235 GMT (8:35 a.m. EDT)

The seven space shuttle Discovery astronauts are flying to Kennedy Space Center this morning in preparation for Saturday's planned liftoff. Their arrival is expected around 10:30 a.m. EDT. The launch countdown remains set to begin ticking at 5 p.m. on Wednesday.

SATURDAY, MAY 20, 2006

"Rollout of Space Shuttle Discovery signifies the last major processing milestone in preparation for our next mission, STS-121," said Space Shuttle Program Manager Wayne Hale. "The entire team has worked tremendously hard to ensure we were prepared to move to the pad, and we are excited to continue moving toward a July launch."

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0215 GMT (10:15 p.m. EDT Fri.)

The mobile launch platform was lowered onto the pad pedestals at 9:14 p.m. EDT Friday. That marks the official time of "harddown" for Discovery's arrival at pad 39B.

0040 GMT (8:40 p.m. EDT Fri.)

ON THE PAD! Discovery has arrived at pad 39B for its planned July 1 liftoff on the second post-Columbia space shuttle test flight. Today's rollout from the Vehicle Assembly Building took eight hours to complete.

In the next few hours and days, the methodical process of hooking up the crew module assess and hydrogen vent arms extending from the launch tower, as well as electrical, propellant, communications and other lines between the ground systems and mobile launch platform will begin.

A hot-fire test for Discovery's auxiliary power unit system is scheduled for Saturday. The APUs provide the hydraulic pressure needed to move the ship's wing flaps and main engine nozzles and deploy the landing gear. Then gantry-like Rotating Service Structure will be moved around Discovery. That will allow the payload bay doors to be opened and the mission cargo to be loaded aboard the shuttle later in the week.

0035 GMT (8:35 p.m. EDT Fri.)

Just a matter of feet left in Discovery's 4.2-mile trip from VAB to the pad.

0025 GMT (8:25 p.m. EDT Fri.)

Less than half a length of the launch platform remaining to go.

0020 GMT (8:20 p.m. EDT Fri.)

The rollout is nearing conclusion tonight. It is getting dark here at Kennedy Space Center as the transporter moves into position on the pad at a glacial speed.

0015 GMT (8:15 p.m. EDT Fri.)

The platform is straddling the flame trench now.

0003 GMT (8:03 p.m. EDT Fri.)

The vehicle is arriving on the flat surface of the pad. A precision laser guidance system helps align the mobile launch platform over the pad pedestals. The crawler-transporter will lower the platform onto the pedestals to complete the rollout.

FRIDAY, MAY 19, 2006
2345 GMT (7:45 p.m. EDT)


The sun is sinking in the west as the rollout elapsed time hits the seven-hour mark.

2335 GMT (7:35 p.m. EDT)

The crawler is designed to keep the mobile launch platform -- and thus the shuttle itself -- level during the five-percent incline up the ramp.

2329 GMT (7:29 p.m. EDT)

The shuttle is in motion again.

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

The crawler has stopped.

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

Discovery is beginning the slow creep up the ramp of pad 39B as rollout passes the six-hour, 30-minute mark.

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

Discovery is right at the pad entrance. This is a planned pause point so that the rollout crew can activate the crawler-transporter's jacking and leveling system. The crawler uses hydraulic lifts to keep the shuttle level during the ascent up the pad's ramp by jacking up the front-end of the mobile launch platform.

2245 GMT (6:45 p.m. EDT)

Discovery is inching ever closer to its seaside pad. The shuttle should reach the pad entrance within the next half-hour and then begin the climb up the five percent incline ramp to the pad surface.

2145 GMT (5:45 p.m. EDT)

Now passing the five-hour point since Discovery began its trek from the Vehicle Assembly Building to the launch pad. The shuttle should be on the pad within the next couple of hours, if all goes well.

2135 GMT (5:35 p.m. EDT)

After the emptied payload-transport canister was loaded onto a specially-designed motorized truck this afternoon at launch pad 39B, that canister has now driven down the pad ramp and into a parking lot. That clears the way for Discovery's arrival this evening.

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

More rollout photos are available here.

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

The transporter features eight tracked tread belts, each containing 57 tread belt "shoes." Each shoe is 7.5 feet long, 1.5 feet wide and weighs approximately 2,100 pounds. Over 1,000 shoes (456 per transporter plus spares) were built by Marion Power Shovel Co. when NASA constructed two transporter in 1965 for Apollo. After finding a crack in one shoe and concerns about fatigue failures in the others, new shoes were made by ME Global Manufacturing and installed in the fall of 2004.

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

About 30 people are aboard the transporter to operate it during today's rollout, including three drivers -- a prime and backup in the front cabin and one in the rear -- a jacking and leveling operator, a control room operator to run crawler systems and talk with the Launch Control Center, two electricians, two electronic technicians and four diesel mechanics for starting, monitoring and shutting down the transporter's engines. The other team members are mechanics watching over the roll and helping with the platform's docking to the launch pad.

2045 GMT (4:45 p.m. EDT)

Now four hours into today's rollout. The overall weight of the transporter, mobile launch platform and shuttle Discovery is 12 million pounds.

2035 GMT (4:35 p.m. EDT)

Shuttle program manager Wayne Hale, on hand for Discovery's rollout to launch pad 39B today, said a preliminary look at complex wind tunnel data shows the ship's redesigned external fuel tank should be safe to fly in July. While stressing that a detailed analysis of the data is ongoing and saying new problems could always crop up, "the preliminary loads indications are good, but we have to wait until they get to the bottom line." Read our full story.

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

The crawler is making the northward turn to head for pad 39B.

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

The shuttle is approaching the point where the crawlerway splits into two paths -- one to pad 39A and the other to pad 39B.

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

Discovery is moving past the tourist observation tower operated by the Kennedy Space Center Visitor Complex. This gantry gives a 360-degree panoramic view of the space shuttle launch pads to the north and Cape Canaveral rocket pads to the south.

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

Meanwhile at launch pad 39B, technicians are lowering the payload-transporter canister out of the Rotating Service Structure. The canister was used to deliver Discovery's cargo to the pad earlier this week. The Leonardo logistics module and equipment being launched on the shuttle will be placed into Discovery's payload bay via the changeout room of pad's Rotating Service Structure.

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

Our collection of photos taken so far during today's rollout is available here.

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

The crawler-transporter carrying Discovery to launch pad 39B is powered by 16 traction motors that feed from two 2,750 horsepower diesel engines. Two 1,065 horsepower diesel engines are used for jacking, steering, lighting and ventilating.

1853 GMT (2:53 p.m. EDT)

The crawler is rolling again.

1845 GMT (2:45 p.m. EDT)

Now passing the two-hour mark in the rollout. But Discovery has come to a stop. A bearing in the transporter is overheating, forcing crews to halt the crawler to apply extra grease and allow the bearing to cool down. The roll is expected to resume in about 20 minutes, a NASA spokesman says.

This is not unusual. Discovery's moves to the pad last year were interrupted several times by hot bearings.

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

The transporter consumes 126 gallons of diesel fuel in each mile it travels from the VAB to pad. The vehicle has a fuel capacity of 5,000 gallons.

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

The crawlerway is 130 feet wide -- almost as broad as an eight-lane highway. Two 40-foot-wide lanes are separated by a 50-foot-wide median strip. The average depth is seven feet.

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

Now 60 minutes into today's rollout of space shuttle Discovery.

1735 GMT (1:35 p.m. EDT)

With Discovery on its way, the gates covering the crawlerway around the VAB have been re-closed. The shuttle is making great progress thus far.

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

Crowds of employees have flocked to the Vehicle Assembly Building area to witness this remarkable sight of the shuttle. Folks are just pulling their cars off the road to get out and snap some pictures.

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

And now the transporter has maneuvered onto the crawlerway. Destination: Pad 39B.

1705 GMT (1:05 p.m. EDT)

The transporter is making its turn to pull onto the main crawlerway. Discovery was mounted to the fuel tank and booster rockets in VAB High Bay 3, which is the northern of the two stacking areas.

1659 GMT (12:59 p.m. EDT)

Discovery has emerged fully from the 52-story vehicle as the shuttle continues to gradually back out of the building.

1657 GMT (12:57 p.m. EDT)

The external tank and solid rocket boosters are peeking out of the VAB now.

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

The initial phase of rollout goes ever so closely as the shuttle is moved out of the tight confines of the Vehicle Assembly Building. Once outside the building, the transporter will rev up to its maximum drive speed of almost one mile per hour.

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

ROLLOUT HAS BEGUN! First motion of space shuttle Discovery's rollout to launch pad 39B occurred at 12:45 p.m. EDT. This 4.2-mile trek will take about eight hours to complete.

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

The diesel engines of the Apollo-era transporter are starting up. Thick black smoke can be seen pouring from the exhaust ducts.

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

The platform has been raised off the pedestals. And the gates on the crawlerway just swung open.

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

Technicians can be seen working in the area around the pedestals upon which the mobile platform rests in the VAB. The transporter jacks up the platform, carries it to the pad and then lowers it onto the pad pedestals. The roll is not expected to start until 12:45 p.m. at the earliest.

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

Rollout has been pushed back at least 30 minutes.

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

The press is gathered outside the VAB doorway to cover the start of Discovery's trip to the launch pad.

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

Good day from Complex 39 at the Kennedy Space Center where space shuttle Discovery is about to begin its move from the Vehicle Assembly Building to launch pad 39B. The crawler-transporter has been positioned beneath the mobile platform for the rollout, the VAB doors are open and weather looks great. First motion is still expected at 12 noon EDT (1600 GMT).

THURSDAY, MAY 18, 2006

Space shuttle Discovery will begin the slow drive to the launch pad Friday afternoon in preparation for its July blastoff on the second of two post-Columbia test flights.

The 8-hour, 4.2-mile crawl to the seaside pad at Florida's Kennedy Space Center is now scheduled to commence at 12 noon EDT (1600 GMT). Earlier plans led to rollout starting at 2 a.m., but activities are running a bit behind schedule.

Discovery has been mounted to its external fuel tank and twin solid rocket boosters aboard a mobile launching platform inside the Vehicle Assembly Building. An Apollo-era transporter will move the fully assembled stack to the pad.

Watch this page for live updates during the rollout.

WEDNESDAY, MAY 17, 2006

The interface verification test has been completed to ensure good electrical connections between the orbiter, boosters, tank and mobile launch platform. Rollout to the launch pad remains scheduled to begin at 2 a.m. EDT (0600 GMT) on Friday.

Meanwhile, Discovery's payloads including an Italian-made cargo module were transported to the pad today to await the shuttle's arrival.

SATURDAY, MAY 13, 2006

Space shuttle Discovery, its external fuel tank and twin solid rocket boosters have been joined together as one atop a mobile launching platform inside Kennedy Space Center's Vehicle Assembly Building.

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FRIDAY, MAY 12, 2006
1655 GMT (12:55 p.m. EDT)


A couple of NASA pictures from today's event can be seen here and here.

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

IN THE VAB! Space shuttle Discovery is now parked inside the cavernous Vehicle Assembly Building where the ship will be mated to the external fuel tank and twin solid rocket boosters this weekend.

A metal "sling" is poised to capture Discovery later today, lifting the shuttle from its transport hauler that carried it from the hangar during the past hour. A heavy-lifting crane then rotates the shuttle vertically and begins the slow, methodical process of hoisting the ship high into the rafters, over to the assembly bay and then carefully lowers Discovery against the awaiting fuel tank for mating.

Once the completed shuttle stack is fully attached, the Integrated Verification Test will be conducted to ensure good electrical and mechanical connections between the vehicle elements.

Rollout to launch pad 39B is scheduled for sometime next Friday. The exact timing will depend on the pace at which the VAB work progresses.

Liftoff of Discovery will occur no sooner than Saturday, July 1 at about 3:49 p.m. EDT (1949 GMT).

1608 GMT (12:08 p.m. EDT)

The stubby-winged shuttle has slid through the doorway. The transporter is still inching forward to position Discovery for its upcoming grapple by the lifting crane.

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

Discovery is rolling over the doorway threshold as it noses into the VAB.

1559 GMT (11:59 a.m. EDT)

The turn is complete. Discovery driving straight into the VAB.

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

With Discovery on its way to the VAB and then the launch pad, doors to the now-vacant Orbiter Processing Facility bay 3 are being closed.

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

The shuttle is making the 90-degree right-hand turn to head for the Vehicle Assembly Building's north side door.

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

The top speed of the transporter while hauling Discovery to the Vehicle Assembly Building is five miles per hour. The V12 engine generates about 335 horsepower.

1548 GMT (11:48 a.m. EDT)

The trailer-like transporter is 106 feet in length, has 76 wheels and weighs 167,000 pounds unloaded and about 327,000 pounds with an orbiter on top. It has a turning radius of 66 feet.

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

The transporter is driving forward now. There is quite a crowd of employees, space program officials and members of the news media lining the roadway.

1542 GMT (11:42 a.m. EDT)

Discovery backed out its hangar and turned 90 degrees onto the roadway that leads to the Vehicle Assembly Building. The transporter will be shifting out of reverse and heading forward now.

1538 GMT (11:38 a.m. EDT)

The Orbiter Transporter System is doing the heavy-duty work during today's move. Originally designed and built for use at Vandenberg Air Force Base in California, the transporter was brought to Kennedy Space Center in 1989 after the West Coast space shuttle launch site was mothballed.

You can envision the OTS as a yellow motorized trailer. At Vandenberg, shuttles were supposed to be prepared for flight in a hangar on the military installation's north side, then ferried aboard the OTS transporter about 17 miles across the hilly terrain to the Space Launch Complex-6 pad on South Base.

In contrast, shuttles in the program's early years at KSC were towed between the hangar and Vehicle Assembly Building with the orbiters' landing gear down.

But with Vandenberg's shuttle plans cancelled after Challenger, the transporter was brought to Florida and pressed into service. It allows NASA to retract a shuttle's landing gear and seal the critical heat-protection tiles around the doors while still in the hangar before rolling out.

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

Discovery has just now fully emerged from its space-age garage at the Kennedy Space Center. Known as Orbiter Processing Facility bay 3, this is the third of three such hangars at the spaceport. Shuttles Atlantis and Endeavour currently occupy the other.

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

Discovery is in motion again.

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

The roll has stopped with Discovery almost half way out the door.

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

The tail of Discovery is sticking out of the hangar doors as this slow roll from the Orbiter Processing Facility continues with caution and care. Sunlight is hitting the ship's three main engines and orbital maneuvering system nozzles, all of which are sporting typical bright red covers.

This initial part of the move occurs at a snail's pace given the close quarters between Discovery and the cocoon-like scaffolding inside the hangar that enclosed the shuttle.

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

MOVE IN PROGRESS! Discovery is slowly backing out of the hangar where crews have spent nine months preparing the ship for its blastoff on mission STS-121. It should take about an hour for the shuttle to roll from the facility over to the Vehicle Assembly Building.

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

The transporter just started its engine!

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

Discovery is still sitting inside the hangar. The shuttle is on the transporter, access platforms are pulled back and the doorway is open. But there has been no further estimate given by NASA on the start time.

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

Everyone continues to anxiously await the transfer's start.

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

A NASA spokeswoman says the current target time to start the move is 10:20 a.m.

1405 GMT (10:05 a.m. EDT)

Crowds have gathered outside of the hangar to witness Discovery's first step on the road to launch under bright blue skies and pleasant temperatures. The shuttle move has not yet commenced.

1345 GMT (9:45 a.m. EDT)

Reporters, photographers and television crews have just left the Kennedy Space Center press site for the short bus ride over to the Orbiter Processing Facility Bay 3 to watch Discovery's morning move to the VAB.

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

The hangar doors are opening up right now, Discovery is atop the transporter and the much-anticipated transfer of the shuttle to Kennedy Space Center's Vehicle Assembly Building should get underway very shortly.

Known as the "rollover" in NASA-speak, this morning's quarter-mile move of Discovery from Orbiter Processing Facility bay 3 to the 52-story VAB.

Once inside the VAB, Discovery will be lifted upright and mounted to its awaiting external fuel tank and solid rocket boosters atop a mobile launching platform. The completed stack is scheduled to be rolled to launch pad 39B in about a week.

1335 GMT (9:35 a.m. EDT)

Good morning once again from KSC for the second attempt to roll space shuttle Discovery out of its hangar.

The lifting sling has been raised out of the way, clearing the Vehicle Assembly Building's center aisle for Discovery's arrival this morning. A broken jack screw on that sling prevented its movement yesterday, forcing NASA to postpone the shuttle move one day.

1023 GMT (6:23 a.m. EDT)

The transfer of space shuttle Discovery from its hangar to the Vehicle Assembly Building is now anticipated around 10 a.m. EDT this morning. Work on the lifting sling is continuing. A view of the ongoing effort is available here.

THURSDAY, MAY 11, 2006
1435 GMT (10:35 a.m. EDT)


SCRUB. Discovery's move to the Vehicle Assembly Building has been postponed for today. The transfer has been rescheduled for 8 a.m. EDT (1200 GMT) on Friday.

NASA spokesman Bruce Buckingham said testing the repaired lifting sling will take a few hours and the approaching stormy weather expected this afternoon and evening forced the decision to scrub the roll.

1245 GMT (8:45 a.m. EDT)

It is expected to take approximately three hours to perform the repairs on the lifting sling, spokeswoman Jessica Rye says. Engineers are debating what, if any, load testing would be required after the jack screw is replaced. Such testing would further delay Discovery's departure from the hangar, she said.

The bright yellow sling will be positioned around Discovery once the shuttle arrives in the Vehicle Assembly Building. Crews will bolt the structure to the shuttle for its rotation into the vertical and hoisting for attachment to the external fuel tank and solid rocket boosters.

Rye explained that the broken jack screw is one of several that keeps the sling flared wide for placement around the shuttle.

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

The problem holding up this morning's roll isn't with Discovery. The issue involves the lifting sling inside the Vehicle Assembly Building that will hoist the shuttle upright.

A broken jacking screw on the spreader beam of the sling has thwarted today's schedule, NASA spokeswoman Jessica Rye says. The situation means the structure remains in the VAB aisle, right where Discovery needs to be parked. Until the device is repaired and moved out of the way, shuttle will stay in its hangar.

The outlook for a roll later today should be clearer in about two hours, Rye said.

Officials are keeping a close eye on possible afternoon thunderstorms, too. Lightning and the chance of adverse weather during the move are concerns, she added.

1140 GMT (7:40 a.m. EDT)

Discovery's move has been delayed two-to-four hours, NASA says.

1115 GMT (7:15 a.m. EDT)

Good morning from the Kennedy Space Center. Discovery's roll out of its hangar is now anticipated to begin no earlier than 8:30 a.m. this morning, a NASA spokeswoman says.

Preparations are a bit behind schedule today. And there's also a large area of rain on the horizon.

Watch this page for live updates during Thursday's move to the VAB and continuing reports leading up to the mission.

WEDNESDAY, MAY 10, 2006

In a move that's both symbolic and substantial for July's space shuttle launch, Discovery will depart its hangar Thursday morning for a quarter-mile transfer to the cavernous Vehicle Assembly Building.

Perched atop the 76-wheel Orbiter Transporter System, the shuttle is scheduled to begin the move around 8 a.m. EDT (1200 GMT). But the timing is considered a fluid situation. Changes can and often do happen for such events.

The shuttle has undergone all of the pre-flight preps for its next mission inside Kennedy Space Center's Orbiter Processing Facility bay 3 since returning from STS-114 last August.

Discovery's external fuel tank and twin solid rocket boosters are waiting inside the Vehicle Assembly Building for the orbiter's arrival. Technicians will spend the next couple of days hoisting Discovery upright and mounting it to the stack.

Rollout to launch pad 39B is targeted for late next week.