BY JUSTIN RAY

Follow the preparations to return America's space shuttle fleet to flight as we chronicle work to ready Discovery for its mid-May blastoff to the international space station.

FRIDAY, MAY 20, 2005

Engineers pumped a half-million gallons of supercold rocket fuel into the shuttle Discovery's external tank today, repeating a test that uncovered two unexpected problems in April. This time around, suspect fuel depletion sensors in the tank worked normally while a hydrogen pressure relief valve continued to cycle more often than normal. Read our full story.

1945 GMT (3:45 p.m. EDT)

NASA decided to only repressurize the liquid hydrogen tank for the final portion of today's test. The vent valve once again cycled 13 times, which appears to rule out any effect from the biopod heaters that were added to the tank after the Columbia disaster.

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

The countdown will be picking up shortly from the T-20 minute mark. During this portion of the test the bipod heaters will be deactivated to determine if they are having any effect on the hydrogen vent valve.

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

The liquid hydrogen vent valve cycled 13 times during the final portion of today's countdown. That's the same number of times it cycled during the last month's test and about twice the normal number of times.

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

T-31 seconds. A cutoff has been called. At this point on a real launch day the orbiter's onboard computers would take over control of the countdown.

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

T-2 minutes. The liquid hydrogen tank is being pressurized. Ground controllers will be carefully monitoring a vent valve that cycled an unusual number of times during the last tanking test.

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

T-3 minutes. The liquid oxygen tank is being brought to flight pressure.

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

T-5 minutes. The hydrogen depletion sensors that malfunction during last month's test are being retested. At this point in a real countdown the orbiter's Auxiliary Power Units would normally be started.

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

The countdown has picked up from the T-9 minute point. The clocks will tick down to T-31 seconds where a cutoff will occur.

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

The countdown has entered a 10-minute built in hold at the T-9 minute mark. When the clocks resume ticking they will count down to the T-31 second point.

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

The countdown has resumed after holding for ten minutes at T-20 minutes. There will be another 10 minute hold at T-9 minutes.

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

The countdown clocks are holding at T-20 minutes for a planned ten-minute built in hold. During this time the NASA test director will brief his team.

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

Ground controllers so far have not noted any problems with the hydrogen depletion sensors inside shuttle Discovery's external fuel tank, NASA spokesman Kyle Herring said. During the last tanking test in April, two of the four sensors malfunctioned. That would have triggered a launch scrub during a real countdown.

Within the last two hours an inspection team has toured the launch pad checking for any build up of ice on the vehicle. The countdown continues to tick down to a planned cutoff at T-31 seconds around 1:35 p.m. EST.

1255 GMT (8:55 a.m. EDT)

The fueling operation entered the stable replenish mode for both liquid oxygen and liquid hydrogen at 8:32 a.m.

The mock countdown will continue until 1:35 p.m. when the countdown will be halted at T-31 seconds. The clocks will then be reset to T-20 minutes and countdown a second time to T-31 seconds, but this time the new bipod ramp heaters will be deactivated in an effort to understand if they are the cause of unusual vent valve cycles seen in the last tanking test.

1154 GMT (7:54 a.m. EDT)

The liquid hydrogen tank reached 98 percent capacity at 7:42 a.m. completing the fast fill portion of the fueling operation. Topping of the tank will continue for another 30 minutes. Fast fill of liquid oxygen continues.

FRIDAY, MAY 20, 2005
1045 GMT (6:45 a.m. EDT)

Liquid oxygen and liquid hydrogen are flowing through the space shuttle Discovery into its rust-colored external fuel tank this morning as NASA's tanking test gets underway.

The so-called "fast-fill" began at 6:24 a.m. for liquid oxygen and 6:31 a.m. for liquid hydrogen. Prior to that a smaller amount of the cryogenic propellants was pumped through the system to chill the fuel lines. It will take about two hours to load the oxygen and about an hour and 15 minutes for the hydrogen. The fueling operation will then enter a stable replenish mode to keep the tanks topped up.

0936 GMT (5:36 a.m. EDT)

The mission management team has given a "go" to begin fueling shuttle Discovery this morning as planned. There are no significant technical issues being worked and the weather conditions are acceptable, a NASA spokesman says. It will take three hours to fill the shuttle's external fuel tank with liquid hydrogen and liquid oxygen.

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

The rotating service structure has moved away from space shuttle Discovery at launch pad 39B tonight. Crews are preparing the seaside complex for fueling the ship before dawn as an engineering exercise to study the external tank.

Here is the test's timeline (all times in EDT):

May 20
02:30 a.m....Pad cleared of personnel
04:00 a.m....Mission management team meets for go/no-go decision
04:30 a.m....Begin a 1-hour built-in hold
05:30 a.m....Resume countdown
05:30 a.m....Begin propellant line chilldown (fueling begins)
08:30 a.m....Fueling complete; stable replenish mode begins
08:30 a.m....Begin a 1-hour 45-minute built-in hold
10:15 a.m....Resume countdown with bipod heater on
01:35 p.m....Countdown is stopped at T-minus 31-second mark
01:35 p.m....Recycle countdown to T-minus 20-minute mark
01:45 p.m....Resume countdown with bipod heater off
02:45 p.m....Final cutoff at T-minus 31-second mark
02:45 p.m....Begin propellant drain back and boiloff
04:00 p.m....Post-test news conference

THURSDAY, MAY 19, 2005

NASA's launch team readied the shuttle Discovery today for a second fueling test Friday to help find the cause of two vexing problems that cropped up during a similar test in April. Other shuttle engineers, meanwhile, are assessing a clearance issue between the shuttle's main Ku-band TV antenna and a new on-orbit inspection boom that could delay the transmission of post-launch images of the ship's redesigned external tank. Read our full story.

FRIDAY, MAY 6, 2005

NASA managers today decided to stage a second tanking test next weekend or shortly after to troubleshoot problems with the shuttle Discovery's external fuel tank. The shuttle then will be hauled back to the Vehicle Assembly Building where engineers will attach the ship to a different set of boosters and a fresh external tank, officials said late today. Read our full story.

WEDNESDAY, MAY 4, 2005
1900 GMT (3:00 p.m. EDT)

The shuttle Discovery's crew strapped in today for a dress rehearsal countdown while program managers continued assessing what work needs to be done - and whether it can be completed in time - for a July 13 launch attempt. Read our full story.

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

Commander Eileen Collins stopped by the Kennedy Space Center press site a short time ago.

"We had a very successful test. It felt to me like it was a real launch day," she told reporters.

Meanwhile, we have posted a movie of today's final countdown from T-minus 9 minutes through the simulated engine shutdown and the subsequent post-abort safing of the shuttle. The video is available to Spaceflight Now Plus subscribers.

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

All seven astronauts have exited Discovery and headed for the slidewires on the west side of the pad's Fixed Service Structure tower to practice hopping into the baskets while wearing their launch suits and helmets. The crew uses the buddy system in scurrying to the baskets -- a group of three and then two pairs.

This will conclude our live play-by-play reports of this morning's successful countdown dress rehearsal for space shuttle Discovery. Commander Eileen Collins will hold a short news briefing a couple of hours from now before the entire crew departs Kennedy Space Center for the flight back to Houston.

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

The crew is beginning to egress the shuttle now, all still wearing their helmets.

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

Once the astronauts complete their post-countdown work, they will climb out the hatch and practice hurrying to the slidewide baskets on the opposite side of the launch tower. These baskets would be used to evacuate the crew to the ground where a fortified bunker awaits. They won't actually ride the baskets today, however.

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

The launch team has completed initial safing of Discovery and the launch pad following the main engine shutdown rehearsal. The team members are going through the procedures they would use if such a scenario happened on launch day. In reality, there have been five such aborts in shuttle history.

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

Today's countdown demonstration has concluded with the simulated ignition and shutdown of Discovery's three main engines. This is known as a Redundant Set Launch Sequencer abort, indicting the shuttle's onboard computers detected a problem during engine start that forced an emergency halt of the countdown before solid rocket booster ignition.

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

CUTOFF! Countdown has been aborted at T-minus 4 seconds as planned in today's simulation. Safing is underway.

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

T-minus 10 seconds. "Go" for main engine start.

1459 GMT (10:59 a.m. EDT)

T-minus 31 seconds. Auto sequence start. Discovery's onboard computers have taken control of the final half-minute of the countdown.

1459 GMT (10:59 a.m. EDT)

T-minus 1 minute. Solid rocket booster joint heaters are being turned off.

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

T-minus 90 seconds.

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

The countdown has resumed after a half-minute hold to verify that the NASA Test Director can override the Ground Launch Sequencer and stop the clock.

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

T-minus 1 minute, 57 seconds and holding. The launch team has stopped the clock at one of the several milestones available for holding the countdown. Once the count passes this point, the liquid hydrogen tank is pressurized on launch day.

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

T-minus 2 minutes, 15 seconds. The astronauts are being instructed to close and lock the visors on their launch and entry helmets.

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

T-minus 2 minutes, 45 seconds. The external tank liquid oxygen tank pressurization simulation has started.

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

T-minus 3 minutes, 30 seconds. Normally at this point in a real countdown, the aerosurfaces and main engine nozzles of Discovery would be moved through computer-controlled test patterns to demonstrate their readiness to support guidance control during launch. However, none of these activities happen today.

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

T-minus 4 minutes. Activation of the APUs is complete with three units simulated to be up and running. Also, the orbiter's heaters have been configured for launch by commander Eileen Collins.

The final helium purge sequence is underway in the main propulsion system. This procedure readies fuel system valves for engine start.

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

T-minus 5 minutes. The "go" has been given for for the pretend Auxiliary Power Unit start. Pilot Jim Kelly would flip 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.

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

T-minus 6 minutes. Pilot Jim Kelly has been asked by Orbiter Test Conductor to simulate pre-starting the orbiter Auxiliary Power Units. This procedure readies the three APU's for their activation after the countdown passes T-minus 5 minutes.

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

T-minus 7 minutes, 30 seconds. The Ground Launch Sequencer is simulating retraction of the Orbiter Access Arm from the crew hatch on the the vehicle. The arm was the passage way for the astronauts to board Discovery a few hours ago.

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

T-minus 9 minutes and counting. The Ground Launch Sequencer is now controlling the final phase of today's countdown to the pretend launch of space shuttle Discovery at 11 a.m. EDT.

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

The countdown will pick up as scheduled in one minute.

1448 GMT (10:48 a.m. EDT)

NASA Launch Director Mike Leinbach has finished his final poll. "We are 'go' to continue the test," he said.

1446 GMT (10:46 a.m. EDT)

The final readiness poll by NASA Test Director Jeff Spaulding has been completed with all launch team members reporting "go". However, Mission Control gave a "no go" due to RTLS weather. But that's not a constraint for continuing the test.

1446 GMT (10:46 a.m. EDT)

Now half-way through this planned hold. Final readiness polls are coming up.

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

T-minus 9 minutes and holding. Countdown clocks have gone into the planned 10-minute. Today's simulated launch remains set for 11 a.m. EDT.

Had this been the actual launch day, NASA would be fighting two problems -- unacceptable weather conditions and a communications glitch with the Eastern Range. Neither will prevent the completion of today's countdown dress rehearsal.

The two issues involve wide spread cloud cover over the space center this morning and the Range's need to command a hold in the countdown if a problem arises, which is prevented by this communications link problem uncovered earlier today.

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

The count will hold in two minutes.

1437 GMT (10:37 a.m. EDT)

Kelly is simulating the reconfiguration of Discovery's Main Propulsion System helium system.

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

Pilot Jim Kelly is configuring the displays inside Discovery's cockpit for launch while commander Eileen Collins enables the abort steering capability on the shuttle. And Mission Control in Houston is loading Discovery's onboard computers with the proper guidance parameters based on the projected launch time.

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

Discovery's onboard computers are switching to the primary ascent software program.

1430 GMT (10:30 a.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.

NASA reports that a communications link problem is being worked between the shuttle and the Air Force-controlled Eastern Range. This is not a problem for today's test. However, it would be a constraint on launch day.

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

The launch team has received a briefing from the NASA test director. Clocks will resume in one minute.

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

As part of today's drill, the weather team is keeping management informed on current conditions and the impact to the launch rules. Conditions are violating the anvil cloud, visibility and cloud ceiling launch weather rules. Also, the Return-to-Launch-Site abort weather constraints are being broken by low clouds right now. The RTLS weather must be acceptable before Discovery can launch to ensure safe conditions at the KSC runway in the event the shuttle had to turn around and land at the Cape a half-hour after liftoff.

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

T-minus 20 minutes and holding. The countdown is taking a scheduled 10-minute pause.

During this time, all computer programs in the Firing Room of the Complex 39 Launch Control Center will be verified to ensure that the proper programs are available for the countdown. Also, preparations will be made to transition Discovery's onboard computers to Major Mode 101 upon coming out of the hold. This configures the computer memory to a terminal countdown configuration.

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

Chief NASA astronaut Kent Rominger is flying approaches into the Kennedy Space Center runway aboard the Shuttle Training Aircraft to evaluate weather conditions. The modified Gulfsteam jet has flying characteristics similar to the space shuttle.

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

T-minus 30 minutes and counting. Coming up on the next planned hold in 10 minutes. The Orbiter Closeout Crew is posing for a photo in the White Room now. They will remain at the pad to assist the astronauts at the conclusion of today's countdown.

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

Just one hour remains in today's countdown. The Orbiter Closeout Crew is simulating final work to secure the White Room next to Discovery's hatch. At this point on launch day, the hatch would be closed, the leak checks wrapping up and the team will be stowing equipment before departing the pad.

1358 GMT (9:58 a.m. EDT)

The Ground Launch Sequencer mainline computer 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.

1355 GMT (9:55 a.m. EDT)

It is a gray, gloomy day at Kennedy Space Center. The weather team is watching some thunderstorms firing up over Orlando that could drift our way this morning. There is a 70 to 80 percent chance that conditions would violate the launch weather rules, if Discovery truly planned to fly today.

1343 GMT (9:43 a.m. EDT)

The Orbiter Closeout Crew has gone through procedures for closure and latching of Discovery's crew module hatch on the port-side of the vehicle.

On the real launch day, pressure integrity and leak tests would now begin to ensure a good seal and pressure stability. But again, the hatch remains open for today's exercise.

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

Clocks currently stand at T-minus 1 hour, 10 minutes and counting. A pair of 10-minute built-in holds are scheduled at T-minus 20 minutes and T-minus 9 minutes, leading to the mock liftoff time of 11 a.m. EDT this morning.

1328 GMT (9:28 a.m. EDT)

The air-to-ground voice checks have been completed with no problems reported.

1322 GMT (9:22 a.m. EDT)

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

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

With the full crew aboard the shuttle, the main focus right now in the countdown on launch morning would be closing Discovery's hatch. However, the hatch will remain open for today's dress rehearsal.

1302 GMT (9:02 a.m. EDT)

The Orbiter Closeout Crew has found a switch mis-configured that caused the communications glitch. It has been reset.

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

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

Robinson has flown on two earlier shuttle missions in the late 1990s. Read his biography here.

1259 GMT (8:59 a.m. EDT)

A communications box that is part of ground support equipment was just replaced at the pad in hopes of clearing up the audio problem in the middeck. However, there was no joy. The team is now double-checking the communications configurations.

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

The launch team and Orbiter Closeout Crew are working to determine why no communications are being received on Discovery's middeck. The crew has been strapped into their seats on the shuttle's lower deck, but communications haven't been established yet due to some sort of problem.

1248 GMT (8:48 a.m. EDT)

Astronaut Wendy Lawrence, mission specialist No. 4, has crawled through the hatch. She will take the middeck's center seat.

Lawrence is a three-time shuttle flier. Read her biography here.

1244 GMT (8:44 a.m. EDT)

Japanese astronaut and Discovery's mission specialist No. 1, Soichi Noguchi, is climbing to the flight deck aft-right seat.

Noguchi will be making his first flight into space on STS-114. Read his biography here.

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

Mission specialist No. 3 Andy Thomas is aboard Discovery now. He is positioned closest to the hatch in the left seat on the middeck.

Thomas is the most experienced space traveler of Discovery's crew. He spent four months living aboard the Russian space station Mir in 1998, plus flew shuttle missions in 1996 and 2001. Read his biography here.

1226 GMT (8:26 a.m. EDT)

Pilot Jim 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. Read his biography here.

1218 GMT (8:18 a.m. EDT)

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

Camarda is a spaceflight rookie, Read his biography here.

1214 GMT (8:14 a.m. EDT)

As shuttle commander, Collins is the first astronaut to board the shuttle. She is taking her forward-left seat on the flight deck.

Collins has flown in space on three earlier missions, becoming the first woman shuttle pilot and commander. Read her biography here.

1209 GMT (8:09 a.m. EDT)

Commander Eileen Collins has made her way across the catwalk-like Orbiter Access Arm to the White Room positioned against the side of Discovery. The closeout crew is helping her don other survival gear as would be the case on launch morning.

1206 GMT (8:06 a.m. EDT)

The Orbiter Closeout Crew is welcoming the Discovery astronauts on the 195-foot level of the tower. The closeout crew will assist the astronauts into the shuttle.

1203 GMT (8:03 a.m. EDT)

Discovery's crew has arrived at launch pad 39B. 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 morning.

1202 GMT (8:02 a.m. EDT)

Leaving the rest of the convoy behind, the AstroVan has driven into the pad and up the ramp.

1159 GMT (7:59 a.m. EDT)

The AstroVan is now passing the tourist observation deck along the crawlerway near pads 39A and 39B. The astronauts are being escorted by KSC security personnel and a low-flying helicopter.

1157 GMT (7:57 a.m. EDT)

The launch team has confirmed at all is in readiness aboard Discovery for the astronauts to start ingressing as planned. The weather officer advises that there may be some light rain at the pad this morning but no thunderstorms or lightning to worry about.

1156 GMT (7:56 a.m. EDT)

The AstroVan is passing the 52-story Vehicle Assembly Building where Discovery was mated to its external tank and solid rocket boosters a month ago. A few reporters across the street at the press site have gone outside to wave at the convoy as it passes by, which is a launch day tradition to say farewell and good luck to the astronaut crews.

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

If Discovery planned to actually fly today, the weather outlook wouldn't be promising. Forecasters predict an 80 percent chance of breaking the launch weather rules at the 11 a.m. EDT simulated liftoff time due to low clouds and thunderstorms.

But for today's dress rehearsal, conditions are acceptable for proceeding with the test as scheduled.

1146 GMT (7:46 a.m. EDT)

Here comes the crew. Led by commander Eileen Collins, the Discovery astronauts have emerged from the Kennedy Space Center crew quarters to board the shiny silver AstroVan for the 7-mile ride from the Industrial Area to launch pad 39B on the edge of the Atlantic Ocean.

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

T-minus 3 hours and counting! Clocks have just resumed ticking after a planned built-in hold in the countdown.

1125 GMT (7:25 a.m. EDT)

All seven astronauts have gotten into the pumpkin-colored 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 7:45 a.m. EDT.

1120 GMT (7:20 a.m. EDT)

The pre-launch crew weather briefing has been accomplished. The commander, pilot and flight engineer received an update on conditions predicted at runways here at Kennedy Space Center, on the U.S. West Coast and the trans-Atlantic abort landing sites in the event a problem forced Discovery to abort the mission and make an emergency return to Earth following liftoff.

For STS-114, a new overseas landing site has been activated in Istres-le-Tube, France. This locale replaces Ben Guerir, Morocco. The other two TAL sites continue to be Moron and Zaragoza, Spain.

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

T-minus 3 hours and holding. If this were a real launch morning, technicians would be finished filling space shuttle's massive external tank with a half-million gallons of liquid hydrogen and liquid oxygen rocket fuel. However, the Terminal Countdown Demonstration Test being conducted today does not involve loading the cryogenic fuels into the shuttle. The TCDT mainly serves as a procedural exercise for the astronauts and launch team.

1035 GMT (6:35 a.m. EDT)

Dressed in festive Hawaiian shirts, Discovery's seven astronauts are gathered around the dining room table in crew quarters for breakfast. They were awakened at 6:05 a.m. EDT to begin the launch day dress rehearsal at Kennedy Space Center.

After a bite to eat, commander Eileen Collins, pilot Jim Kelly and flight engineer Steve Robinson 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 around 7:45 a.m. EDT.

The launch team is not tracking any technical issues as the countdown continues on schedule to today's simulated liftoff time of 11 a.m. EDT this morning.

Clocks current stand at T-minus 3 hours and holding.

TUESDAY, MAY 3, 2005

Space shuttle Discovery's seven astronauts will climb aboard their spaceship at launch pad 39B on Wednesday for the final three hours of a mock countdown that ends with a simulated main engine shutdown and crew evacuation.

The Terminal Countdown Demonstration Test, or TCDT, is a routine pre-flight event for all shuttle crews to rehearse launch day procedures and practice escaping their craft if a problem strikes while still on the pad.

Dressed in day-glow orange partial pressure suits, commander Eileen Collins, pilot Jim Kelly and mission specialists Soichi Noguchi, Steve Robinson, Andy Thomas, Wendy Lawrence and Charlie Camarda will depart the Kennedy Space Center crew quarters around 7:45 a.m. EDT for the half-hour ride to the pad.

One by one, the astronauts will crawl through Discovery's port-side hatch and take their assigned seats in the shuttle's two-level crew module. Collins, Kelly, Noguchi and Robinson will be seated in the cockpit while Thomas, Lawrence and Camarda occupy the middeck.

Meanwhile, the shuttle launch team stationed in Firing Room 3 about four miles away will be running through countdown scripts. The TCDT serves as a full-up launch day dress rehearsal for the team and astronauts alike, albeit without actually pumping fuel into Discovery or even retracting the service gantry enclosing the orbiter on the pad.

Countdown clocks will target a simulated launch time of 11 a.m. EDT. But as Discovery's three main engines pretend to ignite at T-minus 6 seconds, a fault will be detected that forces the powerplants to shut down moments before liftoff. Such an aborted takeoff has happened for real five times in shuttle program history.

Still wearing their cumbersome spacesuits, the crew will exit the shuttle and scurry to the emergency slide-wire baskets on the west side of the launch pad tower. These baskets would be used to quickly transport a shuttle crew to the ground where a fortified bunker awaits if a nightmarish scenario ever occurred. Discovery's crew plans to hop into the baskets but not actually ride them off the tower. In fact, astronauts have never had to escape the pad in such dramatic fashion.

After completing the training lesson and returning to quarters at the Operations and Checkout Building, the five-man, two-woman crew will head to the KSC runway for departure back to Houston around 2:30 p.m. EDT.

Watch this page for live updates throughout the practice countdown, starting with crew breakfast around 6:30 a.m. EDT.

SUNDAY, MAY 1, 2005

As space shuttle Discovery's astronauts jetted into Kennedy Space Center Sunday night for their launch countdown dress rehearsal, mission commander Eileen Collins voiced support for NASA's decision to delay liftoff until July. Read our full story.

FRIDAY, APRIL 29, 2005

The shuttle Discovery's launch on the first post-Columbia mission is on ice until at least July 13, officials said today, primarily because of recent tests showing ice buildups pose more of a potential impact threat than previously thought. Read our full story.

1434 GMT (10:34 a.m. EDT)

NASA Administrator Michael Griffin confirms that the space shuttle's return to flight will be delayed until the July launch window.

1230 GMT (8:30 a.m. EDT)

NASA has scheduled two news conferences for today when it is expected to formally announce the space shuttle's return to flight will be delayed until July.

At 1430 GMT (10:30 a.m. EDT), NASA Administrator Michael Griffin and Associate Administrator for Space Operations William Readdy will speak with reporters at Headquarters in Washington.

Then at 1530 GMT (11:30 a.m.), Space Shuttle Program Manager Bill Parsons, Deputy Space Shuttle Program Manager Wayne Hale and International Space Station Program Manager Bill Gerstenmaier will hold a news conference at the Johnson Space Center.

THURSDAY, APRIL 28, 2005

NASA managers are debating whether to delay the shuttle Discovery's launch on the first post-Columbia mission to July because of time needed to complete ice debris analysis, implement proposed fixes and to resolve a handful of nagging problems, sources say. Read our full story.

WEDNESDAY, APRIL 20, 2005

As expected, NASA managers today announced a May 22 target date for shuttle Discovery's liftoff on the first post-Columbia mission, saying time needed to close out a handful of open issues precluded an attempt at the May 15 opening of the actual launch period. Read our full story.

1956 GMT (3:56 p.m. EDT)

NEW DATE. NASA has set Sunday, May 22 as the new target launch date for space shuttle Discovery. Liftoff on that day will be approximately 1:03:49 p.m. EDT.

The one-week delay gives the space agency more time to complete final reviews and analysis in the run-up to the returning the shuttle fleet to flight.

We'll be updating all of our pages noted in the left-hand column of the Mission Status Center -- the flight plan, mission timelines, etc. -- to reflect the new launch date.

1945 GMT (3:45 p.m. EDT)

Today's news conference has not yet begun. We'll post details from NASA officials as soon as the briefing starts.

1245 GMT (9:45 a.m. EDT)

NASA has scheduled a 3:30 p.m. EDT (1930 GMT) news conference to discuss return to flight efforts for the space shuttle program. It is widely expected that senior managers will announce a delay -- a week or more -- from the targeted May 15 launch date for Discovery.

See a chart of the available launch windows in the May 15-June 3 period here.

NASA has until June 3 to launch Discovery or else wait until mid-July to ensure favorable lighting conditions to photograph the redesigned external tank during ascent.

Watch this page for live reports during today's news conference for the very latest information.

THURSDAY, APRIL 14, 2005

The space shuttle's redesigned fuel tank sailed through a critical tanking test today, giving NASA managers increased confidence about launching Discovery on the first post-Columbia shuttle mission next month. Read our full story.

Additional coverage for subscribers:
VIDEO: DISCOVERY FUELING TEST GETS UNDERWAY QT
VIDEO: INSPECTORS COMPLETE CHECKS OF TANK AFTER FUELING QT
VIDEO: POST-TEST NEWS CONFERENCE WITH TOP NASA MANAGERS QT
AUDIO: LISTEN TO POST-TEST BRIEFING FOR IPOD
VIDEO: HIGHLIGHTS OF EXTERNAL TANK PRE-FLIGHT PREPS QT
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2120 GMT (5:20 p.m. EDT)

Today was last non-standard event in the pre-launch flow leading to liftoff of Discovery, Leinbach said.

"The rest of the pad flow is well understood and not unique," he said.

The schedule has three days between now and May 15 with no work planned, giving the space agency a slight bit of margin to deal with problems that crop up.

"The fact we have three days is not that bad."

The payload will be installed into Discovery by month's end and the Terminal Countdown Demonstration Test in which the seven astronauts will climb inside the shuttle for a launch day rehearsal (without fueling the external tank) is scheduled for April 29.

But Hale cautioned that selecting the launch date will not be pressure-driven. There is still much engineering work left to do, plus ensuring Atlantis is ready to fly a rescue flight if Discovery suffers a problem.

"We are being driving by completion of the work, nothing else," Hale said.

NASA has a launch window of May 15 through around June 3 or else wait till mid-July to ensure Discovery ascends in daylight conditions for photography reasons to monitor the tank.

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

"I can't think of a test objective not met today," Leinbach says.

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

"(The tank) performed exactly as we expected it to perform," Otte says of the foam and redesigns.

2107 GMT (5:07 p.m. EDT)

"We are very pleased with the overall performance of the tank," says Neil Otte, chief engineer of the external tank project office.

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

"We had an outstanding day today," deputy shuttle program manager Wayne Hale says, adding that the tank, orbiter and launch pad functioned properly today.

"The test went off virtually without a hitch," launch director Mike Leinbach says. "The launch team performed very, very well. It was a good exercise for us."

2003 GMT (4:03 p.m. EDT)

The countdown reached T-minus 31 seconds where clocks were halted as scripted. The launch team will soon start draining the external tank following today's successful test. NASA plans a news conference in about an hour to give some level of detail on the tanking exercise and its results.

1959 GMT (3:59 p.m. EDT)

T-minus 2 minutes and counting. The gaseous oxygen vent hood has just been retracted from atop the external fuel tank as today's countdown simulation reaches the final moments.

1816 GMT (2:16 p.m. EDT)

The inspection team is departing the launch pad now after nearly three hours of up-close examinations of the space shuttle. The team members are headed to the firing room to give a detailed report to mission managers. During the inspections, the 8-person team said the tank and shuttle appeared in good condition.

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

Based on the revised timeline following this morning's delay in the start of fueling, the launch team is targeting the mock liftoff time of Discovery around 4 p.m. EDT. Countdown clocks will run to T-minus 31 seconds and stop there. That is the point in which Discovery's onboard computers assume control of the countdown from the ground launch sequencer.

A post-test news conference is planned for approximately 5 p.m. EDT for NASA managers to provide details on today's fueling exercise and results of the external tank foam insulation inspections under cryogenic conditions.

1706 GMT (1:06 p.m. EDT)

The external tank remains in "stable replenish" mode to keep the separate liquid oxygen and liquid hydrogen supplies tanks 100 percent full.

The ice team continues its work at pad 39B. NASA is not reporting any problems.

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

Fueling was successfully completed shortly past 11 a.m. EDT this morning after a smooth, three-hour cryogenic tanking operation.

"It looks like we have a clean vehicle," a NASA spokesman says.

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."

Following tanking procedures, the inspection team was dispatched to the pad to check the vehicle. The 8-person team is comprised of engineers and safety officials from NASA, United Space Alliance and tank-builder Lockheed Martin. At the conclusion of their two-and-a-half-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.

1434 GMT (10:34 a.m. EDT)

The tanking test is passing the two-hour, 20-minute mark. All continues to progress successfully as the external fuel tank is loaded with its supply of 500,000 gallons of liquid oxygen and liquid hydrogen.

1331 GMT (9:31 a.m. EDT)

After the slow-fill process to initially begin loading the external tank, the launch team transitioned to the fast-fill mode at 9:01 a.m. for liquid oxygen and 9:12 a.m. on the liquid hydrogen side. The fast-fill continues until each cryogenic tank inside the external tank is nearly full. NASA says today's tanking test is going well.

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

There are actually two tanks inside the shuttle's orange bullet-shaped tank. The liquid oxygen tank occupies the top third of the external tank. It will be filled with 143,000 gallons of liquid oxygen chilled to minus 298 degrees Fahrenheit. 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.

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

The fueling process is being orchestrated by engineers in the safe confines of the Kennedy Space Center's Launch Control Center located about four miles from Discovery at launch pad 39B.

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

NASA says fueling operations are continuing with no problems reported. It will take about three hours to pump 500,000 gallons of liquid oxygen and liquid hydrogen into the tank.

Around 11:30 a.m. EDT, the 8-member ice and debris inspection team will head into the pad to begin a multi-hour job of walking up and down the fixed tower and mobile launch platform to examine the external tank foam, boosters and orbiter following fueling.

1220 GMT (8:20 a.m. EDT)

GO FOR FUELING. The probability for thunderstorms and damaging hail is not high enough to thwart today's scheduled fueling test, NASA officials have decided, clearing the way for the launch team to begin pumping liquid oxygen and liquid hydrogen propellants into space shuttle Discovery. The process to load the external tank commenced at 8:14 a.m. EDT.

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

We are still awaiting word from NASA on whether the tanking test will go forward today or if the operation needs to be delayed 24 hours due to stormy weather conditions possible this afternoon. The forecast calls for a 30 percent chance of severe thunderstorms today and a 60 percent chance of hail if those storms do develop.

0952 GMT (5:52 a.m. EDT)

Worries about severe thunderstorms and hail have put today's fueling test on a temporary hold this morning. Mission managers were briefed on the weather forecast a short time ago and decided not to begin loading the external fuel tank as planned.

Another weather outlook will be provided to officials at 7:30 a.m. EDT. If the predictions have not changed, NASA expects to return the protective rotating service structure around Discovery to shield the orbiter from hail that could damage the thermal tiles. Moving the RSS would delay the tanking test until tomorrow.

WEDNESDAY, APRIL 13, 2005

Technicians will pump a half-million gallons of super-cold rocket fuel into space shuttle Discovery's redesigned external fuel tank at launch pad 39B on Thursday during an engineering test that doubles as a countdown rehearsal.

Called a tanking test, this exercise will follow a countdown script similar to the one that launch team members will follow on the real liftoff day.

The cocoon-like rotating service structure enclosing Discovery is scheduled for retraction tonight, revealing the orbiter for the first time since last Thursday when the shuttle arrived at the pad.

Final preparations for fueling occurs overnight, with the launch pad being cleared of all workers by around 2:30 a.m. EDT.

Countdown clocks will enter a planned 60-minute built-in hold at the T-minus 6 hour mark at 4:30 a.m. EDT. During this time, the team will have a chance to catch up on any work that could be running behind schedule. Also during the hold, the Mission Management Team will meet to review the progress of work and any outstanding issues before giving final approval to begin fueling.

Cryogenic liquid hydrogen and liquid oxygen should start flowing from storage tanks at the pad into Discovery at 5:30 a.m. EDT as the clocks resume at T-minus 6 hours and counting. It will take about three hours to fully fill the giant external tank.

A three-hour hold at T-minus 3 hours starts at 8:30 a.m. EDT -- about the same point that fueling reaches completion. The "ice team" is then dispatched to pad 39B to conduct a thorough inspection of the tank, its foam, the orbiter, solid rocket boosters and ground structures. The team will be looking for any ice or frost formations.

Terminal Count commences at 11:30 a.m. EDT as clocks proceed ticking into the final three hours. Further built-in holds are planned at the standard T-minus 20 and T-minus 9 minute points.

For this test, a hold will be called at the T-minus 31 second mark around 3:20 p.m. EDT. Mission managers will order a cutoff of the simulated launch attempt at 3:30 p.m. EDT, allowing technicians to begin draining the liquid hydrogen and liquid oxygen from the tank.

The tanking test is designed to expose the shuttle to cryogenic temperatures for the inspections, examine how the tank's foam performs under real-life conditions and give the launch team experience fueling a space shuttle for the first time in more than two years.

NASA plans to hold a post-test news conference at 4:30 p.m. EDT to discuss results of the event.

We will provide live updates on this page throughout the day!

THURSDAY, APRIL 7, 2005
0700 GMT (3:00 a.m. EDT)

The shuttle Discovery has been hauled to launch pad 39B at the Kennedy Space Center, the first shuttle "rollout" since Columbia's ill-fated mission and a major milestone on the road to resuming shuttle flights in May. Read our full story.

Video coverage for subscribers only:
VIDEO: TIME LAPSE MOVIE OF DISCOVERY ARRIVING AT PAD QT
VIDEO: TIME LAPSE MOVIE OF GANTRY ENCLOSING DISCOVERY QT

VIDEO: DISCOVERY ROLLS OUT OF VEHICLE ASSEMBLY BUILDING QT
VIDEO: HEADING DOWN THE CRAWLERWAY QT
VIDEO: TURNING AT CRAWLERWAY JUNCTION QT
VIDEO: ROLLING WITH PAD 39A AS BACKDROP QT
VIDEO: ON NORTHWARD IN THE EARLY EVENING QT

VIDEO: PREVIEW OF DISCOVERY'S MISSION DIAL-UP | BROADBAND
VIDEO: THE SPACE STATION WITHOUT SHUTTLE DIAL-UP | BROADBAND
VIDEO: MEET DISCOVERY'S SEVEN ASTRONAUTS DIAL-UP | BROADBAND
VIDEO: DISCOVERY HOISTED INTO POSITION FOR TANK MATING QT
VIDEO: WALK ALONGSIDE DISCOVERY DURING TRANSFER TO VAB QT
VIDEO: TIME-LAPSE MOVIE OF DISCOVERY LEAVING HANGAR QT
VIDEO: SPED UP VERSION OF HANGAR DEPARTURE MOVIE QT
VIDEO: TIME-LAPSE MOVIE OF SHUTTLE ROLLING INTO VAB QT
VIDEO: SPED UP VERSION OF VAB ARRIVAL MOVIE QT
VIDEO: NASA'S STEVE POULOS TALKS WITH REPORTERS QT
VIDEO: PAYLOAD BAY DOORS CLOSED IN HANGAR QT
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0620 GMT (2:20 a.m. EDT)

The crawler-transporter has done its job of hauling Discovery from the Vehicle Assembly Building and is now departing the pad.

This will conclude our live reports on rollout after a long day at Kennedy Space Center. We hope you enjoyed our Live ShuttleCam views of the 10.5-hour roll.

Watch this page for live updates during next week's tanking test.

0605 GMT (2:05 a.m. EDT)

Discovery's launch platform come to rest on the pad pedestals at 1:16 a.m. EDT (0516 GMT), officially marking the ship's delivery to the seaside complex. The orbiter access arm and gaseous oxygen vent arm have been extended from the launch tower to Discovery's crew module and top of the external tank, respectively.

0436 GMT (12:36 a.m. EDT)

ON THE PAD! America has a space shuttle on the launch pad again.

Discovery has arrived at pad 39B for its planned mid-May liftoff to return the shuttle fleet to space after a two-year suspension of flights to redesign the external fuel tank, develop new inspection techniques and thermal protection system repair concepts following the February 1, 2003 loss of Columbia.

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. The rotating service structure will swing into position to enclose Discovery later tonight.

The next major event on the road to launch is scheduled for next Thursday when a countdown test is conducted in which the external fuel tank will be fully loaded with a half-million gallons of liquid oxygen and liquid hydrogen. This so-called "tanking test" will give the launch team practice performing an actual countdown and flowing propellants for the first time since Columbia. Also, engineers will thoroughly examine the tank, foam and redesigned bipod area under cryogenic conditions. Fueling is targeted to begin around 4:30 a.m. EDT with a mock launch time around 2 p.m. EDT. The countdown will be halted at T-minus 31 seconds.

NASA officials continue to target launch of Discovery on its 12-day mission to the International Space Station for May 15. However, all padding in the pre-launch schedule has been used up by delays over the past few weeks getting the shuttle out of its hangar and to the pad. Any change in the launch date is not expected to happen until after the tanking test is accomplished.

0434 GMT (12:34 a.m. EDT)

Time elapsed since rollout began now stands at 10 hours, 30 minutes. The milestone we are waiting for is the "harddown" call, which means the crawler transporter has lowered the mobile launch platform with Discovery onto the launch pad pedestals.

0425 GMT (12:25 a.m. EDT)

Still inching along with a matter of yards to go.

0407 GMT (12:07 a.m. EDT)

The platform is straddling the flame trench now, almost in position at the pad.

0404 GMT (12:04 a.m. EDT)

Now passing the 10 hour mark in Discovery's roll from the VAB to pad 39B. The vehicle is arriving on the pad surface. 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.

0355 GMT (11:55 p.m. EDT Wed.)

The transporter is still moving, climbing the pad incline at a glacial rate.

0325 GMT (11:25 p.m. EDT Wed.)

Ascent up the launch pad ramp is underway.

0314 GMT (11:14 p.m. EDT Wed.)

Discovery is rolling once again after waiting through a hardware glitch.

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

The old card was plugged into another slot and exhibited problems like earlier tonight, which NASA says confirms that the card was to blame for the leveling system issue. The new card is installed, and the crawler is being powered up again. The roll is expected to restart in about 15 minutes, putting Discovery on launch pad 39B around midnight or so.

0250 GMT (10:50 p.m. EDT Wed.)

The suspect card inside the crawler has been replaced. The replacement fits more snuggly into the port than the previous one, which was described by NASA as loose. It is expected that within 15 to 30 minutes it will be known if the problem has been corrected, allowing Discovery to resume its trip to the launch pad.

0229 GMT (10:29 p.m. EDT Wed.)

NASA says an electronics card, known as programmable logic controller, is believed to be causing the leveling system issue. At no time during the initial attempt to roll up the launch pad ramp was Discovery out of level, a spokeswoman says. Workers are swapping out this suspect card right now in hopes of correcting the problem. If this successfully fixes the discrepancy between the two level measurements, rollout could resume in a little while. However, if the card turns out not to be the fault then engineers must continue troubleshooting.

The space agency wants to get the shuttle on the pad and enclosed within its protective service gantry overnight due to forecast storm weather on Thursday.

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

Engineers continue to troubleshoot the leveling system that keeps the shuttle safe and stable during the climb up the launch pad ramp. A NASA spokesman says efforts are underway to examine an electronics card in the system used to determine the attitude of the mobile launch platform. The shuttle currently sits at the pad's entrance after backing down the ramp.

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

International Space Station commander Leroy Chiao spotted Discovery from 225 miles above Earth today and snapped this photograph of the shuttle as it was being rolled from the Vehicle Assembly Building to launch pad 39B. See the picture here.

0058 GMT (8:58 p.m. EDT Wed.)

A problem has been encountered while moving up the launch pad ramp. A NASA spokesman says the readings from the mobile launch platform and crawler-transporter indicating how level the platform is during the roll are not in agreement.

"They didn't get very far up the ramp and realize that the gauges weren't synched up," NASA spokesman Bruce Buckingham said. "They were not sure if the vehicle was truly level."

Discovery is reversing course and descending down the ramp to reach a level spot so that the platform and crawler readings can be calibrated.

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

0034 GMT (8:34 p.m. EDT Wed.)

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

0014 GMT (8:14 p.m. EDT Wed.)

The shuttle is finally moving again as it heads into the pad in darkness.

0005 GMT (8:05 p.m. EDT Wed.)

Discovery is parked right at the pad entrance. This is a planned pause point, a NASA spokesman says, 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.

WEDNESDAY, APRIL 6, 2005
2345 GMT (7:45 p.m. EDT)

As darkness falls over Kennedy Space Center, Discovery is now reaching the perimeter fence to enter into pad 39B.

2304 GMT (7:04 p.m. EDT)

Now passing the five-hour mark in today's rollout of Discovery. The shuttle should reach the pad perimeter fence in about 30 minutes and then begin the 45-minute climb up the five percent incline ramp to the pad surface.

2250 GMT (6:50 p.m. EDT)

Launch pad power systems have been activated in advance of the shuttle's arrival.

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

The roll team says its expects to arrive at the pad 39B perimeter in about 60 minutes.

2220 GMT (6:20 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.

2205 GMT (6:05 p.m. EDT)

NASA officials project Discovery should make its way up the launch pad ramp around 8:15 p.m. EDT and be positioned over the pad's pedestals at 9 p.m. The gantry-like rotating service structure is expected to enclose around the orbiter during the night.

Rollout continues to progress smoothly and without problem.

2130 GMT (5:30 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.

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

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

2110 GMT (5:10 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.

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.

The overall weight of the transporter, mobile launch platform and shuttle Discovery is 12 million pounds.

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

Discovery is approaching the point where the crawlerway splits into two paths -- one to pad 39A and the other to pad 39B. At this junction is the KSC Visitor Center's Observation Deck, which provides spectators an elevated view of the pads. Photographers have gathered there, anxiously awaiting Discovery to pass by and then make the northward turn to pad 39B.

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.

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

Crowds of employees, tourists from the Kennedy Space Center Visitor Center and news media have flocked to Complex 39 to witness this remarkable sight of the shuttle inch its way to pad 39B.

Rollout of Discovery continues under mostly sunny skies, with a light breeze and warm temperatures. NASA has not reported any problems during today's move from the Vehicle Assembly Building -- the first to occur in over two years.

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

The International Space Station will be soaring overhead around 4:30 p.m. EDT today. Expedition 10 commander Leroy Chiao hopes to snap some pictures of shuttle Discovery with an 800 mm lens.

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

Despite the shuttle's notable height at 184 feet, the spacecraft is dwarfed by the overall height of the Vehicle Assembly Building. The 525-foot tall VAB was built in the 1960s to support assembly of the giant Saturn 5 moonrockets for Apollo.

1824 GMT (2:24 p.m. EDT)

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

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

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

1810 GMT (2:10 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 one mile per hour.

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

ROLLOUT HAS BEGUN! First motion of space shuttle Discovery's rollout to launch pad 39B occurred at 2:04:36 p.m. EDT. This 4.2-mile trek will take six to eight hours to complete.

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

The official "go" has been given to start rolling to the launch pad in the next few minutes.

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

NASA is describing the foam issue on the tank as a "hairline crack" that is no concern for flight.

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

Engineers have decided that the small foam crack on the external tank is not a problem and Discovery can safely fly as-is, a NASA spokesman just said. Rollout is expected to commence around 2:15 p.m. EDT (1815 GMT).

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

Rollout has been delayed at least another hour while engineers at the tank-manufacturing facility near New Orleans review the foam crack situation. Once an engineering recommendation is made on either fixing the crack in the VAB, at the pad or leaving it as-is for flight, officials will set a new rollout time.

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

Rollout preparations continue, pending the final 'go' from mission managers to begin the move today. Workers are preparing to raise the crawler-transporter to essentially pick-up the mobile launch platform upon which Discovery stands.

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

Also under discussion now is the amount of time spent on the job today by the rollout crew. The team members are constrained in the number of hours they can work while handling flight hardware. If rollout is delayed to 2 or 3 p.m., that time limit could be exceeded during the entire trip to the pad and post-arrival chores.

Meanwhile, management continues to review a small foam crack in the intertank area of the external fuel tank. Debate is ongoing to determine whether repairs should be performed before rolling out or once at the pad, or even if the crack is a problem at all.

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

Engineers continue to assess a small crack in the foam insulation on the external tank just above the access door on the intertank area. NASA says it does not appear to be a major crack but would need to be repaired. Now being debated is whether the repair should be done in the VAB or at the pad.

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

Based on the latest timeline, NASA spokesman George Diller says, rollout is now expected to start no sooner than 1 p.m. EDT. That assumes the external tank foam does not require a quick repair in the VAB.

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

The inspection teams are briefing launch director Mike Leinbach on their findings. Discussions are focused on a suspect patch of external tank foam insulation and whether any fix would need to be accomplished in the VAB or once at the launch pad.

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

As part of these final inspections, workers are looking closely at an area of foam insulation around one of the external tank access doors, NASA says.

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

Weather conditions are favorable for today's rollout. Skies to the west and north are partly cloudy and clear over the launch pad. There is a zero percent chance of lightning.

1607 GMT (12:07 p.m. EDT)

The team is preparing to switch the power feed from the VAB-supply to the mobile launcher platform.

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

The rollout is being managed from Firing Room 3 of the Launch Control Center. Shuttle launch director Mike Leinbach is in control of today's operation.

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

Things are running somewhat behind schedule today. But NASA says the rollout to the pad should begin between 12:30 and 12:45 p.m. EST. "The team is just being extra cautious," NASA spokesman George Diller says.

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

Workers in the VAB are performing final inspections, going from level to level to ensure there are no problems and all platforms are clear of the shuttle vehicle.

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

The crawler is beginning its slow drive into the VAB now. Obviously, the rollout to the pad has been delayed past noon EDT.

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

The shuttle transporter remains parked outside the VAB. Once it moves into the assembly building, crews must hook it up to Discovery's launch platform and prepare for the trip to the launch pad. When rollout to pad 39B will start today is unclear at this moment.

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

Preparations continue for today's rollout of space shuttle Discovery to launch pad 39B. The crawler-transporter that will carry the fully assembled shuttle to the seaside pad is parked just outside the Vehicle Assembly Building. NASA says the Apollo-era transporter will be moved into the VAB and attached beneath the shuttle's mobile launch platform shortly.

TUESDAY, APRIL 5, 2005

With the first post-Columbia shuttle flight a month and a half away, engineers are still assessing what sorts of damage might result from impacts of foam debris falling from the shuttle's redesigned external fuel tank. Read our full story.

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

Discovery will begin rolling out of the Vehicle Assembly Building at 12 noon EDT (1600 GMT) on Wednesday, NASA has just decided. This timing is based on completion of work in the VAB.

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

Technicians have completed final adjustments to tiles on space shuttle Discovery's nose, setting the stage for the momentous move from the Vehicle Assembly Building to launch pad 39B sometime Wednesday morning.

The rollout will position NASA one critical step closer to the returning the shuttle to flight after more than two years spent grounded on Earth to fix the external fuel tank and develop new inspection and thermal protection system repair concepts in the wake of Columbia's tragic ending.

"I believe we are ready to roll out and go launch in the May time frame," space shuttle program manager Bill Parsons said this morning.

A firm time for Discovery to begin the 4.2-mile journey to the launch pad has not been set. The schedule will depend on last-minute prep work that is now underway. The move is running late because of difficulty installing so-called gap fillers in the black thermal protection tiles on the shuttle -- work that was carried into the VAB from the shuttle's Orbiter Processing Facility hangar.

"We've been working on some tile around the nose landing gear door. Normally when you come over from the OPF to the VAB, you have some measurements that you take as you close that door and some gap fillers that you have to install," Parsons said, noting this was a routine task in the VAB.

But given the number of tiles that were replaced on the nose landing gear area, workers had many more gap fillers to install than we typically performed in the VAB, Parsons said. Complicating matters was the humidity level in the 52-story building, which hampered the curing of adhesive.

Recent "pull tests" were conducted successfully to check the tiles' integrity.

"All of the tiles passed those tests, and now we are in work removing the platforms away from the vehicle so that we can do this rollout.

"So the platform retraction work is now ongoing. As we do that retraction, we are doing a complete inspection of the vehicle. Mainly we are really concentrating on the external tank to make sure there is no damage to that external tank...So currently the remaining work we have in front of us is just retracting those platforms, doing those inspections and then dispositioning anything that we find with the appropriate engineering organizations that we need to. It looks like sometime early tomorrow morning we'll be able to roll out."

Once at the pad, workers will get the shuttle hooked up to ground systems and propellant lines in advance of a full-up countdown rehearsal scheduled for next Thursday, April 14. Dubbed a tanking test, the external tank will be loaded with a half-million gallons of super-cold liquid hydrogen and liquid oxygen to exercise the launch team, the equipment and offer the chance to examine the tank when filled with the cryogenic fuels.

NASA officials view the test as one of the major hurdles to clear between now and launch. But exactly when Discovery will fly remains fuzzy. The shuttle can launch during a window extending from May 15 and June 3 to ensure a daytime ascent for the best possible photography by ground, airborne and even onboard cameras. A launch on May 15 would occur at 3:50 p.m. EDT, while June 3 provides a liftoff time around 8:15 a.m. EDT. The unprecedented camera coverage will document the tank and reveal any debris striking the shuttle.

"The May 15 (date) is just a goal. It is just the opening of the window. We will have to assess this over the next 30-40 days to see where we are getting to. We have no issue with moving that launch date to the right (on the calendar) if we need to, and the good thing is we have till June 3," Parsons said.

But to make May 15, NASA has no time to spare. All margin built into the pre-launch schedule has been used up by delays getting Discovery out of its hangar and assembled inside the VAB.

"We do not have any contingency days left. We are trying to plan this out at this point in time. Until we get rolled out to the pad it is difficult for us to assess when we may be able to do the tanking test. If we roll as originally planned tomorrow morning, then the tanking test on the 14th is doable. But we need to get out to the pad and start some of that serial work that needs to be completed before we do the tanking test. At that point after the tanking test, we'll reassess our capability to the make the launch date," Parsons said.

"I think, currently, when you have no contingency days going into this flow and we haven't done this in quite some time and the fact that we're being much more meticulous than we have been ever in the past, therefore I would say it is fairly 50-50 right now that we'll make the opening of the window. But we are going to keep marching towards that and at some point in time we'll make the right assessments to move that launch date to the right if required."

MONDAY, APRIL 4, 2005
1410 GMT (10:10 a.m. EDT)

Humidity in the Vehicle Assembly Building is interfering with routine work on shuttle Discovery, further postponing the ship's move to launch pad 39B. NASA says rollout will happen Wednesday morning at the earliest.

An agency spokeswoman says the humidity is delaying thermal protection system work, specifically tile bonding, forcing Discovery's extended stay inside the 52-story facility. Roll to the pad could start as early as 2 a.m. EDT (0600 GMT) Wednesday, if weather and work schedules permit.

Discovery has been bolted to its external fuel tank and solid rocket boosters. An Apollo-era transporter will move the fully assembled stack to the pad for final preparations leading to liftoff in May on the first post-Columbia shuttle mission.

1312 GMT (9:12 a.m. EDT)

Discovery's rollout to the pad appears to be slipping again. Delays encountered over the weekend are expected to postpone the shuttle's departure from the Vehicle Assembly Building to 6 a.m. EDT (1000 GMT) Wednesday.

SUNDAY, APRIL 3, 2005

NASA's timeline for rollout of Discovery from the Vehicle Assembly Building was adjusted today. The move to pad 39B is now scheduled to start at 6 a.m. EDT (1000 GMT) Tuesday.

SATURDAY, APRIL 2, 2005

Space shuttle Discovery's arrival at launch pad 39B has been pushed back a day -- to Tuesday morning -- so technicians in the Vehicle Assembly Building have more time to complete pre-flight work and testing, NASA said Friday.

The 8-hour, 4.2-mile crawl to the seaside pad at Florida's Kennedy Space Center is now scheduled to commence at 12:01 a.m. EDT (0401 GMT). Earlier plans led to rollout starting Monday morning, just before sunrise.

A NASA spokesman said work in the VAB is taking longer than anticipated.

Discovery was transferred from its hangar to the 52-story assembly building a few days ago and successfully bolted to its external fuel tank and solid rocket boosters on the mobile launch platform.

The lifting "sling" and crane that hoisted Discovery from the ground to its position for mating to the tank was detached Thursday, followed by ordnance installation work on the vehicle. Electrical connections for the liquid oxygen and liquid hydrogen systems were continuing Friday, the space agency said, along with final closeout chores on the fully assembled shuttle stack.

Installation of a new digital camera in Discovery's umbilical well was delayed to Friday and the interface verification test slipped to Saturday. The shuttle will be powered up for the verification checkout.

Meanwhile, Michael Kostelnik, NASA's deputy associate administrator for the shuttle and station programs, said Friday that two more weeks will be required before the agency can provide necessary information to the Stafford-Covey Return to Flight Task Group.

"Everybody would have liked to have had this work completed sooner," he told reporters. "But it's just kind of the way it is, and we're not going to cut short any of these milestones just to make an arbitrary date."

The task group, which is charged with conducting an independent oversight of NASA's implementation of the Columbia Accident Investigation Board's recommendations, had scheduled a public meeting Thursday. But the lack of some data from NASA forced an indefinite delay in the proceedings.

"As we strive to complete our assessment of NASA's activities in response to the Columbia Accident Investigation Board's recommendations, the Task Group has determined that meaningful conclusions must await data and information being developed for the upcoming program milestones," group co-chairman Dick Covey said.

NASA must accomplish its Debris Design Verification Review and Program Design Certification Review to exhaustively examine procedural and design changes before handing over information to the Task Group.

The Stafford-Covey group's work is widely seen as a wild-card in NASA's plans to launch Discovery in mid-May.

FRIDAY, APRIL 1, 2005

NASA mission managers today rescheduled rollout of Discovery to launch pad 39B. The move is now slated to begin at midnight Monday evening/Tuesday morning local time at Kennedy Space Center (12:01 a.m. EDT; 0401 GMT).

Watch this page for live updates during the roll.

THURSDAY, MARCH 31, 2005
2040 GMT (3:40 p.m. EST)

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. Technicians have finished bolting and torquing Discovery to the tank, accomplishing the so-called "hard mate" process.

The interface verification test begins tomorrow to ensure good electrical connections between the shuttle elements. The test will "make sure everything is talking to each other," a NASA spokeswoman explained.

Also upcoming is installation of a new digitial camera in the umbilical well on Discovery's belly. This camera will snap pictures of the external fuel tank to determine its condition after ascent for downlink to engineers.

The 4.2-mile trip from the VAB to launch pad 39B is targeted to begin no sooner than 6:30 a.m. EDT (1030 GMT) on Monday.

WEDNESDAY, MARCH 30, 2005
1850 GMT (1:50 p.m. EST)

The first phase of mounting space shuttle Discovery to its external fuel tank was completed earlier today. This so-called "soft mate" in NASA-speak is the initial connection between ship and tank. Underway now is work to firmly bolt the two together.

"Things are going well," a Kennedy Space Center spokeswoman said.

NASA hopes to roll the fully assembled space shuttle to launch pad 39B as early as next Monday.

TUESDAY, MARCH 29, 2005
2000 GMT (3:00 p.m. EST)

Discovery has been raised from its transporter and rotated vertically in the Vehicle Assembly Building today. Work to mate the shuttle with its external tank and boosters begins mid-evening tonight, a NASA spokesman says.

"I could not be more proud of the team that spent the last two years working on Discovery. We are extremely excited to reach this point in the processing for flight," said Stephanie Stilson, NASA Vehicle Manager for Discovery. "Seeing the orbiter roll to the VAB is the culmination of all of that hard work. We look forward to a safe Return to Flight."

Discovery has been fitted with 41 modifications to comply with the Columbia Accident Investigation Board, including addition of the new Orbiter Boom Sensor System for in-space inspections of the wing leading edges and thermal protection tiles, sensors in the wings to detect debris impacts and a new digital camera to document the tank during ascent.

"This effort has taken a talented team dedicated to meticulously preparing the vehicle and implementing all the modifications for a safe Return to Flight," Bill Parsons, shuttle program manager, said in a statement following this morning's move to the VAB.

0750 GMT (2:50 a.m. EST)

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

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 Monday or Tuesday. The exact timing will depend on the pace at which the VAB work progresses over the next few days.

Liftoff of Discovery will occur no sooner than Sunday, May 15 at 3:50 p.m. EDT (1950 GMT). NASA has until June 3 to get the mission launched or else wait until July 12 to permit a daylight ascent for favorable photography of the redesigned fuel tank.

0735 GMT (2:35 a.m. EST)

This is a sight we have not seen in more than two years -- a space shuttle arriving in the assembly building to prepare for its launch into Earth orbit.

0733 GMT (2:33 a.m. EST)

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

0727 GMT (2:27 a.m. EST)

The shuttle is making the turn into the Vehicle Assembly Building's north side door.

0725 GMT (2:25 a.m. EST)

The top speed of the transporter while hauling Discovery to the Vehicle Assembly Building is 5 miles per hour. The V12 engine generates about 335 horsepower.

0720 GMT (2:20 a.m. EST)

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

0714 GMT (2:14 a.m. EST)

The Orbiter Transporter System is doing the heavy-duty work during this morning'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.

0704 GMT (2:04 a.m. EST)

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.

0653 GMT (1:53 a.m. EST)

The tail of Discovery is sticking out of the hangar doors as this super-slow roll from the Orbiter Processing Facility continues. Technicians are moving the shuttle with extreme caution and care.

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 ship.

0628 GMT (1:28 a.m. EST)

MOVE IN PROGRESS! Discovery is slowly backing out of the hangar where crews have spent months preparing the ship for its blastoff on mission STS-114. It should take approximately 30 minutes or more for the shuttle to roll from the facility over to the Vehicle Assembly Building.

0620 GMT (1:20 a.m. EST)

The transporter has started its engine.

0536 GMT (12:36 a.m. EST)

The hangar doors are opening up right now, Discovery is bolted 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 evening's quarter-mile move of Discovery from Orbiter Processing Facility bay 3 to the 52-story VAB is both a significant and visual signal that the space shuttle program is nearing its return to flight.

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 early next week.

0527 GMT (12:27 a.m. EST)

A NASA spokesperson here at KSC says there are no constraints with Discovery standing in the way of tonight's roll. Officials are simply waiting for last-minute preparations inside the Vehicle Assembly Building to be completed before the move commences, the spokesperson reported.

0505 GMT (12:05 a.m. EST)

It is a windy, almost chilly night here at Kennedy Space Center. But crystal clear conditions are affording a spectacular view of the starry sky.

0445 GMT (11:45 p.m. EST Mon.)

A large group of reporters, photographers and TV crews has gathered outside of Discovery's hangar to cover tonight's move. The hangar doors remained closed at this time, however. The rollout is scheduled to occur no sooner than midnight.

MONDAY, MARCH 28, 2005
2345 GMT (6:45 p.m. EST)

The move of Discovery has been shifted earlier to 12 midnight (0500 GMT) this evening. Watch this page for live updates during the transfer.

1945 GMT (2:45 p.m. EST)

Mating of Discovery to its transporter is nearing completion, a NASA spokesman says. But the drive to the VAB has slipped a bit more. Departure of the shuttle from its hangar is now targeted for around 2 a.m. EST (0700 GMT).

1400 GMT (9:00 a.m. EST)

Discovery's rollover was delayed because of problems aligning the 76-wheel transporter vehicle that will carry the shuttle the half-mile from its hangar to the Vehicle Assembly Buidling, says NASA spokesman Bruce Buckingham.

After difficulties overnight, the motorized transporter was backed out from beneath the orbiter so workers can make another attempt to align the transporter.

"They are trying again right now," Buckingham said.

If all goes well, Discovery could leave its Orbiter Processing Facility hangar around 11 p.m. EST (0400 GMT). Once in the towering Vehicle Assembly Building, the shuttle will be attached to its external fuel tank and solid rocket boosters. The assembled vehicle will be moved to the launch pad next week.

1340 GMT (8:40 a.m. EST)

Discovery's move to the Vehicle Assembly Building has been delayed until 11 p.m. EST (0400 GMT) tonight. Check this page throughout the day for updates.

1135 GMT (6:35 a.m. EST)

Trouble aligning the trailer-like transporter beneath space shuttle Discovery during the night has temporarily delayed today's move to the Vehicle Assembly Building. NASA says the transfer should occur sometime this afternoon.

SUNDAY, MARCH 27, 2005

NASA reports that preparations remain on track for Monday's transfer of Discovery from its processing hangar to the 52-story Vehicle Assembly Building at Kennedy Space Center. That milestone move is currently targeted for no earlier than 10 a.m. EST (1500 GMT). Watch this page for live updates on Monday.

SATURDAY, MARCH 26, 2005

The 76-wheel Orbiter Transporter System is parked just outside shuttle Discovery's hangar doors, poised to carry the ship to the Vehicle Assembly Building on Monday. The motorized transporter will be driven into the hangar -- officially known as Orbiter Processing Facility bay 3 -- Sunday evening so Discovery can be lowered upon it and bolted down.

When the roll to the assembly building will occur remains a fluid situation. A specific time has not been pinned down. A NASA spokeswoman said today that it won't occur any earlier than 8:30 a.m. EST on Monday.

Earlier this week, technicians completed work inside Discovery's payload bay to fix wiring concerns. Fasteners in wire trays were causing minor chafing on the tubing surrounding the wires. The wire tray covers were removed, the chafe protection added, and then borescope inspections were performed to ensure there was clearance between the fasteners and the wires, NASA said.

The payload bay doors were closed Friday, following final radiator inspections and completion of closeout photography. The yellow "strong back" structures mounted on the 60-foot long doors were detached this morning.

FRIDAY, MARCH 25, 2005
1950 GMT (2:50 p.m. EST)

Space shuttle Discovery's payload bay doors have been closed as final preparations continue for the ship's departure from its processing hangar sometime Monday.

Workers are cleaning the payload bay and closing up the mid-body access panels today. The precision weighing of Discovery and determining its center of gravity occurs this weekend as part of routine last-minute work in the hangar. A transporter will then position itself under the shuttle for the upcoming move to the Vehicle Assembly Building.

The exact time of that quarter-mile trip from the hangar to VAB has not been set. But NASA says it will happen mid-day or later on Monday.

"The vehicle is in good shape. we just have some paperwork to finish closing out. we will work through the weekend as needed to get everything finished," Kennedy Space Center spokesman Bruce Buckingham said.

Once inside the VAB, Discovery will be mated to its external fuel tank and solid rocket boosters. Rollout to launch pad 39B is targeted for Monday, April 4.

Watch this page for continuing updates over the weekend and live reports Monday during this critical milestone on the road to returning the space shuttle to flight.

FRIDAY, MARCH 18, 2005

Space shuttle Discovery remains parked inside its Kennedy Space Center hangar while technicians make repairs to internal wiring and adjust the vital thermal seals on landing gear doors.

The ship's long-awaited quarter-mile move from the hangar to the cavernous Vehicle Assembly Building has been delayed a couple of times this month, most recently a five-day slip announced today. NASA says the so-called "rollover" transfer to the VAB is now targeted for either Easter Sunday, March 27, or Monday, March 28.

Once inside the VAB, Discovery will be hoisted vertically and mated to its external fuel tank and twin solid rocket boosters atop a mobile launching platform. The completed stack will roll to launch pad 39B about a week later, on April 3 or 4.

"The rollover milestone is moving to March 27 (previously March 22), due to additional work needed on wiring in the payload bay and on the main and nose landing gear doors," the space agency said today. "Because work is scheduled to end late that day, rollover could take place the morning of March 28. If the work is completed safely and correctly, the orbiter could be moved to the VAB earlier than March 27."

The wiring trouble stems from problems found aboard sister-ship Endeavour, which is in the midst of a major overhaul period.

"On orbiter Endeavour, wiring was found in a cable tray in the payload bay that showed the fasteners were causing minor chafing on the tubing surrounding the wires. Boroscope inspections of wire trays on Discovery are complete, and some wires will require additional work. The wire tray covers will be removed and chafe protection will be added."

Meanwhile, efforts to install seals and perform checks on the landing gear doors on Discovery's belly are almost finished, NASA says. The doors will be closed for flight while Discovery is still inside the hangar, and remain shut until seconds before landing. The seals are critical because they protect the vehicle from the super-hot temperatures during re-entry into Earth's atmosphere.

In the Space Station Processing Facility at Kennedy Space Center, the Italian-built Multi-Purpose Logistics Module Raffaello that will launch aboard Discovery is being filled with equipment. Workers have stowed racks containing supplies for the outpost. Additional bags loaded with cargo will be stuffed into Raffaello over the next couple of weeks before the module's outer hatch is closed in mid-April. Raffaello then moves to the launch pad for mounting into Discovery's payload bay for the ride to orbit.

Discovery remains scheduled for launch around 3:50 p.m. EDT (1950 GMT) on May 15. The available launch period to ensure a daytime liftoff and separation of its external fuel tank extends through June 3.

THURSDAY, MARCH 17, 2005

The shutdown of an orientation control gyroscope aboard the international space station will not impact the planned launch of the shuttle Discovery in May, officials said Thursday, even though only two of the lab's four gyros will be operating when the orbiter arrives. Read our full story.

WEDNESDAY, MARCH 16, 2005

A circuit breaker aboard the international space station popped open early Wednesday, interrupting power to one of the three operational gyroscopes used to maintain the lab's orientation in space. NASA officials said the failure would have no immediate impact and that the space station's orientation could be maintained with just two gyros while engineers study the problem. Read our full story.

See our STS-114 Mission Index for previous stories.