Spaceflight Now



Video Coverage




The most complete source of video from the countdown, launch and mission of space shuttle Discovery is available here!

Video Collection



The Mission




Orbiter: Discovery
Mission: STS-121
Launch: July 4, 2006
Time: 2:38 p.m. EDT (1838 GMT)
Site: Pad 39B, Kennedy Space Center, Florida
Landing: July 17 @ 9:14 a.m. EDT
Site: Shuttle Landing Facility, KSC
Video collection

Mission Status Center

Landing Day Timeline

Master Flight Plan

NASA TV Schedule

Countdown Timeline

Launch Timeline

Shuttle/ISS Calendar

STS-121 Quick-Look

Launch Windows Chart

Ascent Data Packet

Timeline Walkthrough

Rendezvous Burns

Undocking Timeline

Key Personnel List

STS-121 Mission Index

STS-114 Archive



The Crew




Veteran shuttle commander Steven Lindsey leads a seven-person crew launching aboard Discovery for the STS-121 mission.

Crew Quick-Look

CDR: Steven Lindsey

PLT: Mark Kelly

MS 1: Michael Fossum

MS 2: Lisa M. Nowak

MS 3: Stephanie Wilson

MS 4: Piers Sellers

MS 5: Thomas Reiter

Manned Spaceflights

Current Demographics

Spacewalk Statistics



The Vehicle




As America's third reusable space shuttle to fly, Discovery has successfully completed 31 missions since 1984.

STS-121 Hardware

Launch/Landing Chart

Shuttle Flight History





BY JUSTIN RAY

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

THURSDAY, JULY 13, 2006
1255 GMT (8:55 a.m. EDT)


The Discovery astronauts took the day off today, relaxing and enjoying the view from space after a hectic week in orbit highlighted by three spacewalks and work to transfer supplies and equipment to the international space station. Engineers, meanwhile, continue analysis of two seemingly minor issues with Discovery's hydraulic system.

Read our full story.

WEDNESDAY, JULY 12, 2006

The Discovery astronauts chalked up a third successful spacewalk today, demonstrating repair techniques that could help a future shuttle crew fix damage to a ship's wing leading edge panels. Just before bidding the astronauts good night, mission control informed commander Steve Lindsey that engineers were monitoring two potential issues with the shuttle's hydraulic system.

Read our full story.

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

Astronauts Piers Sellers and Mike Fossum re-entered the space station's Quest airlock module, closed the hatch and began repressurization at 2:31 p.m. to officially end the third and final spacewalk planned for Discovery's mission.

The 68th spacewalk staged in the space station era lasted seven hours and 11 minutes, pushing Sellers' and Fossum's three-EVA total to 21 hours and 29 minutes. The total for all 68 station-era spacewalks now stands at 412 hours and 23 minutes by 42 U.S. astronauts, 13 Russian cosmonauts, one Frenchman, one Canadian and one Japanese astronaut. Sellers, a veteran of three previous spacewalks, has now logged 41 hours and 10 minutes of EVA time.

Read our update story.

1832 GMT (2:32 p.m. EDT)

Airlock repressurization commenced at 2:31 p.m., marking the official end time for the spacewalk after a duration of 7 hours and 11 minutes. That brings the total STS-121 EVA time to 21 hours and 29 minutes.

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

Sellers and Fossum are inside the airlock and the hatch is closing.

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

The astronauts are just about done with the grapple bar relocation chore on the station truss structure. They'll be traveling back to the airlock module and closing the hatch to the EVA shortly.

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

The spacewalk has reached the six-hour mark. The astronauts have been asked to perform a "get-ahead" task of moving a robot arm grapple fixture that would be used in replacing a space station cooling unit in the future.

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

The sample box has been closed up for its trip back to Earth aboard Discovery. Mike Fossum is about ride the station arm up to the airlock, while Piers Sellers manually climbs the route. This third and final EVA of the mission is winding down.

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

Now it's cleanup time for the astronauts. They are checking their gloves for any repair material residue and putting away the repair tools.

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

The IR camera testing is underway now to inspect samples that were repaired and some that remain damaged. Sellers is operating the camera from above the sample box while standing on the station arm. Fossum is down in the payload bay using a sunshade to shadow the samples.

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

The spacewalkers have finished all of the repair demonstrations that time will allow. They tested the NOAX material on five different RCC samples. Inspections using the IR camera is coming up.

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

Astronauts Piers Sellers and Mike Fossum are wrapping up their simulated heat shield repair work, touching up and smoothing out an experimental sealant they've spread over deliberately cracked and damaged panels of wing leading edge material.

"The best practice for this is to have an old house in Houston," Sellers said as he used a putty knife to smooth the NOAX sealant.

"Done that," laughed Fossum.

Read our update story.

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

As the spacewalkers finish this fifth repair, the plan Mission Control just radioed up to the crew will see Sellers and Fossum return to put finishing touches on two earlier samples. Then they will get ready to test the new infrared inspection camera on the sample box starting about 10 minutes before the next orbital sunrise.

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

Fossum has completed the first higher priority sample. An extra dab of goo material was needed to fill in a divot. The spacewalkers are now moving to the next RCC sample, which will be their fifth of the day.

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

Three hours into the spacewalk.

Astronauts Piers Sellers and Mike Fossum began their first heat shield repair test run around 9 a.m., after Fossum relatched a loose safety tether. Using a high-tech caulk gun, Sellers squeezed out thick NOAX sealant on a wing leading edge sample with deliberate cracks and/or gouges. The idea is to find out how the heat-resistant material performs in weightlessness, how easy or difficult it might be to spread over cracks using putty knife applicators and how suspended air bubbles out at higher temperatures.

"OK. We're starting to get goo," Sellers said as he squeezed the trigger ofthe caulk gun. "Got goo, good goo!"

Read our update story.

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

Sellers and Fossum have put the NOAX material on two lower priority samples. And now that the temperature is warm enough on one of the primary samples, they have begun repairing it.

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

Nearing the two-and-a-half hour mark of today's EVA. The spacewalkers have completed the repair demonstration on the first sample. They are proceeding with preps on two more samples now.

The crack repair material uses a pre-ceramic polymer sealant impregnated with carbon-silicon carbide powder, together known as NOAX (short for non-oxide adhesive experimental). The NOAX material is temperature sensitive and the ideal condition for the repairs is when the samples are between 100 and 35 degrees Fahrenheit, with the temperature decreasing.

1310 GMT (9:10 a.m. EDT)

There are 12 carbon-carbon panel samples carried in this box in the rear of Discovery's payload bay. Eight of them have different sized cracks or gouges, two are meant to be imaged with the infrared inspection camera and two are blank.

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

The worksite around the sample pallet has been prepared by the spacewalkers. The first sample repair test is about to start. The order in which the samples are repaired will be determined on temperature. The samples are ranked in priority because the repair material is temperature-sensitive. The first sample is a lower priority one because the temperature is a few degrees out of limits right now for one of the higher ranked samples.

1243 GMT (8:43 a.m. EDT)

The box of shuttle thermal protection system samples mounted in the back of the payload bay has been opened. The spacewalkers will be testing repair techniques on these pre-damaged samples this morning.

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

The test of an inspection infrared camera has been performed by Sellers. He took pictures of Discovery wing leading edge carbon-carbon panels and a 20-second movie with this camera.

The FLIR Systems ThermaCAM S60 Infrared Camera is being tested as a possible way to inspect RCC panels for damage in space.

Depending on how far away the crew member is, the camera's field of view can cover 52 inches, or about two RCC panels, to 83 feet, the entire wing leading edge at a time, according to the press kit. The camera can record temperature variances from minus 400 degrees Celsius to 1,200 egrees Celsius. The video is recorded at a 0.6 Hz frame rate and is saved on internal memory and then transferred to a memory card.

1210 GMT (8:10 a.m. EDT)

Piers Sellers, on his sixth EVA, is aboard the space station's Canadian-built robotic arm. The spacewalkers are departing the airlock module to get started with today's shuttle inspection and repair test demonstration.

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

The spacewalkers are getting equipment and tools rounded up for the EVA. They are installing a foot restraint on the end of the station's robot arm. Sellers will ride the arm down to Discovery while Fossum travels hand-over-hand to the payload bay. En route, Sellers will use an infrared camera to image shuttle wing leading edge RCC panels for a demonstration test.

1121 GMT (7:21 a.m. EDT)

EVA begins. With the flip of switches to put their spacesuits on internal battery power, Sellers and Fossum officially started the spacewalk at 7:20 a.m. EDT. The hatch has been opened. The crew should be climbing out shortly.

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

Depressurization of the Quest airlock is underway for the start of today's spacewalk by astronauts Piers Sellers and Mike Fossum. This will be the third EVA in five days for the two Discovery crewmates.

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

The Discovery astronauts are set for a third spacewalk Wednesday, this one to test tools and a temperature-sensitive sealant with the consistency of peanut butter that may prove useful for repairing small cracks or other minor damage to critical wing leading edge panels.

Astronauts Piers Sellers and Mike Fossum are scheduled to begin the planned six-and-a-half-hour excursion around 7:13 a.m. Wednesday, exiting the international space station's Quest airlock module and making their way to a sample pallet at the back of Discovery's cargo bay.

Compared to two earlier spacewalks - one to test a long inspection boom as a work platform and another to repair a stalled robot arm transporter on the space station - Wednesday's outing "is more like a kind of a careful, meticulous lab experiment," Sellers said.

Read our preview story.

TUESDAY, JULY 11, 2006

The Discovery astronauts, working through a relatively relaxed day of space station equipment and supply transfers Tuesday, said the shuttle's trouble-free launch and lack of significant impact damage show NASA is finally ready to put the Columbia tragedy behind it. Read our full story.

MONDAY, JULY 10, 2006

Space station flight director Rick LaBrode sweated bullets going into today's spacewalk to fix a stalled robot arm transporter on the international lab complex. But months of planning, tests and simulations paid off with a successful repair job, clearing the way for resumption of station assembly.

Read our full story.

1902 GMT (3:02 p.m. EDT)

EVA ends. Airlock repressurization began at 3:01 p.m., concluding the spacewalk for a total duration of 6 hours and 47 minutes.

Sellers and Fossum have logged 14 hours and 18 minutes of EVA time during the first two spacewalks of Discovery's mission. A third excursion is planned for Wednesday.

1858 GMT (2:58 p.m. EDT)

Initial checks by flight controllers indicate no problems with the cable connections with the new reel assembly.

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

The spacewalkers have entered the Quest airlock module, and the "go" has been given to re-close the hatch. The EVA ends when airlock repressurization begins.

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

Mike Fossum is back at the airlock. This second spacewalk of Discovery's mission is nearing conclusion.

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

Flight controllers in Houston are beginning to check out the station railcar system to ensure the new umbilical reel assembly and the various connections hooked up during the spacewalk are working normally.

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

Now approaching the six-hour mark in today's spacewalk. The reel replacement work is essentially complete now. Sellers has returned to the payload bay to finish cleanup work there. Fossum is wrapping things up on the station truss.

Getting the reel assembly into position took some time. The spacewalkers experienced some stuggles along the way.

"Ready? Say when," Sellers said as they made an attempt.

"Three, two, one, now," Fossum said and they pushed.

"No."

"OK, let me rotate it a little bit more," Fossum said. "That's the max rotation there, it's up against the stop."

"OK."

"Yeah, it shouldn't be up against the stop," pilot Mark Kelly radioed from Discovery's flight deck.

"I know it, I know it," Fossum said. "But we're kind of feeling it."

"It looks like, hmmm, 30 degrees maybe out," Sellers said.

After another unsuccessful attempt, the astronauts checked to make sure nothing was blocking the mechanism and then tried again. This time, they were successful.

"Got it!" one exclaimed. A moment later, a second latch was engaged.

"Yay! Two for two."

"Great job, guys," Kelly radioed.

"What else could happen, man?" one of the astronauts quipped.

"Don't ask."

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

The spacewalkers are working to bolt down the reel and make all of the cable connections between the station and the new assembly.

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

The reel assembly has slid in place, finally, with cheers from the spacewalkers. It took quite a bit of effort to get the reel to fit inside its slot.

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

Astronaut Mike Fossum is struggling to install a new cable reel assembly on the space station's solar array truss to restore redundant power, data and video between the lab and a robot arm transporter cart. Spacewalker Piers Sellers, meanwhile, back in Discovery's cargo bay, ran into problems with an apparently disengaged latch holding his jet backpack in place.

Read our update story.

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

Fossum has gotten Sellers' SAFER right-side lock latched in place again.

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

Mission Control has devised a new plan. Fossum hasn't had any luck getting the new cable reel installed in its slot. And since Sellers' SAFER backpack has a tether on it, he will climb up to the station from the payload bay to assist with the reel. They will fix Sellers' backpack later.

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

The crew is worried that Sellers' jet backpack has come loose. The SAFER backpack would be used for rescue if a spacewalker gets untethered from the spacecraft. Fossum will secure the reel assembly and then climb down to the payload bay to help fix Sellers SAFER.

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

Ever so gently, Fossum is sliding the new cable reel into the space station truss backbone. The spacewalker's feet are anchored on the end of the station's robot arm.

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

Mike Fossum has arrived at the open slot on the space station truss structure where the new reel assembly will be mounted. Piers Sellers is continuing to work in the payload bay to lock down the old unit on the support carrier. The crew is discussing allowing Fossum to begin the installation work solo.

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

Sellers is now putting final touches on the old assembly to stow it for landing. Fossum, meanwhile, is in the process of carrying the new unit up to the station.

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

Fossum has pulled the new reel assembly out of the shuttle payload bay. He'll hand that to Sellers and then put the failed assembly into the bay for the ride back to Earth.

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

In space shuttle Discovery's payload bay, Piers Sellers has taken the failed reel assembly from Mike Fossum. Sellers is standing on a foot platform in the bay while Fossum remains on the station arm.

Fossum will be picking up the new assembly and maneuvering back over to Sellers. The spacewalkers will swap out the 334-pound devices. Fossum takes the old one and puts it into the payload bay launch location where the new one rode to space.

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

This reel assembly is 5 feet x 5 feet x 2.5 feet. It has a mass of 334 pounds.

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

The reel assembly has been removed from the station. Fossum is holding on to it while the station robot arm moves the astronaut to the shuttle payload bay where the device will be stowed for return to Earth. Sellers is climbing his way down to the shuttle.

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

Now three hours into the spacewalk. Mike Fossum is standing on a foot platform attached to the space station robot arm. He will hand-carry the reel assembly while riding the arm back to Discovery's payload bay.

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

The spacewalkers are returning to the S0 truss for removal of the failed reel assembly. Flight controllers report the crew is right on the timeline.

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

The space station external stowage platform has received the ammonia pump module. The unit will remain on this storage rack until needed in the future.

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

The pump module is in the hands of the spacewalkers, literally. The robot arm has released the 1,400-pound unit to the astronauts for a manual installation onto the stowage platform.

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

Sellers and Fossum are stepping away from the railcar work and heading over to the space station's External Stowage Platform 2 where the pump module is waiting on the end of the robot arm for installation on the spares rack. The spacewalkers will take the pump away from the arm and manually place the unit on the platform.

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

The spacewalkers are working together to retract the railcar's cut umbilical cable. The reel assembly will be removed and replaced as the EVA progresses. Fossum has been prepping the old reel for removal from the station by unhooking electrical connectors and bolts.

1403 GMT (10:03 a.m. EDT)

The new umbilical assembly has been bolted to the mobile transporter, the crew reports.

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

Sellers is working to replace the failed umbilical assembly for the space station railcar. The device's cable cutter fired for unreasons in December. Since the blade cannot be retracted, the entire unit has to be changed out.

Here is some further background on the system from the mission press kit:

If the mobile transporter ever gets stuck between stations, procedures have always allowed for an astronaut to remove a hung cable using a spacewalk; cutting the cable was always a last option. The cable cutter design dates back to the Space Station Freedom days when it was envisioned that large propulsive elements, with potentially explosive hydrazine, were expected to be translated on the mobile transporter. In those days, there was not enough time to complete a spacewalk before the situation would have become dangerous (hydrazine becomes explosive once it freezes), so the cable cutter was placed on station.

Today, the station design does not have those explosive dangers so station managers are evaluating the need for the cable cutters. For now, a spacewalk would be conducted to remove the cable in the future if the MT ever gets hung up. Cutting the cable renders the (Trailing Umbilical SystemReel Assembly) unusable on orbit.

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

Astronauts Piers Sellers and Mike Fossum attached a grapple bar to the new space station pump module mounted in Discovery's cargo bay. Lisa Nowak and Stephanie Wilson, operating the space station's robot arm, plucked it out of the astronauts' gloved hands one hour into the spacewalk and slowly lifted the 1,400-pound freezer-sized module out of the bay.

Read our update story.

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

Now 90 minutes into this planned 7-hour spacewalk.

This is the 20th staged from the U.S. Quest airlock module, the 67th since space station assembly began in 1998 and the Discovery crew's second spacewalk. Going into today's excursion, 58 astronauts from the United States, Russia, Japan, Canada and France have logged 398 hours and 25 minutes of station spacewalk assembly time, including seven hours and 31 minutes by Sellers and Fossum Saturday.

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

The crewmates are climbing along the outside of the space station to reach the S0 central truss segment to begin the railcar umbilical repair work.

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

The space station's arm now has a firm grasp on the pump module for the lift up to the storage platform on the outpost. The spacewalkers will position the pump on that rack later in the EVA today.

This pump device is known as the External Active Thermal Control System Pump Module. It is a spare for later use in the station's cooling system that radiates heat into space. The pump modules circulate liquid ammonia at a constant rate to a network of cold plates and heat exchangers located on the external trusses and U.S. segment modules. There are two pump modules on the station, one located on the S1 truss and the other on the P1 truss.

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

Using a little bit of elbow grease, the spacewalkers are picking up the pump module about 18 inches to enable to robot arm to latch on. They have installed the grapple fixture.

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

The spacewalkers are busy down in the payload bay of space shuttle Discovery preparing the spare pump module for transfer to the space station. Sellers has been working beneath the cargo carrier platform to retrieve a grapple bar for installation on the pump module. That bar will be used by the station's robot arm to hoist the pump from Discovery up to the spare parts rack on the station. Meanwhile, Fossum has been working on the thermal insulation around the payload.

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

Piers Sellers and Mike Fossum have floated out of the airlock hatch. This is Sellers' fifth EVA and the second for Fossum.

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

EVA begins. The spacewalkers switched their suits to internal battery power at 8:14 a.m., marking the official start of today's seven-hour EVA outside the space station complex.

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

The most critical task planned for Discovery's mission is arguably the one that must be accomplished to permit continued assembly of the international space station: repair of a stalled robot arm transporter on the station's unfinished solar array truss that "killed itself" late last year.

Astronaut Piers Sellers and Mike Fossum plan to venture out of the station's Quest airlock module today to begin a planned seven-hour spacewalk.

Read our preview story.

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

Discovery astronauts Piers Sellers and Mike Fossum are inside the International Space Station's airlock making final preparations for today's spacewalk. They are suited up and depressurization of the airlock is underway. The EVA is expected to begin shortly after 8 a.m.

SUNDAY, JULY 9, 2006

The Discovery astronauts are enjoying a slightly more relaxed day in space today, settling in for relatively routine supply transfers from the shuttle to the international space station and gearing up for a critical spacewalk Monday. Read our full story.

SATURDAY, JULY 8, 2006

With the Discovery astronauts chalking up a surprisingly successful spacewalk, NASA's Mission Management Team today cleared the shuttle's critical nose cap and wing leading edge panels for re-entry and expressed optimism two final question marks about the ship's heat shield will be resolved Sunday. Read our full story.

2052 GMT (4:52 p.m. EDT)

The first spacewalk for Discovery's mission is over. Repressurization of the airlock began at 4:48 p.m. for a duration of 7 hours and 31 minutes.

2032 GMT (4:32 p.m. EDT)

Both spacewalkers are back inside the airlock. They are working to close the hatch now. The EVA end time is determined when repressurization begins.

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

Climbing hand over hand, the spacewalkers are now making their way up the docking port and the exterior of the station.

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

Astronaut Mike Fossum, anchored to the end of a 100-foot space crane positioned at one end of the space station's solar array truss, pretended to make heat shield repairs today, measuring the forces imparted to the untried space crane to judge its stability as a repair platform.

The tests appeared to go well and while some exercises were easier to accomplish than others, the shuttle robot arm/inspection boom combination seemed stable enough to serve as a repair platform if real repairs are ever needed.

If an engineering analysis confirms that, future shuttle crews would have a way to reach virtually any part of a shuttle's heat shield to make repairs, regardless of whether the space station was available. That could be a factor in any decisions down the road to approve a mission to repair the Hubble Space Telescope. Because the observatory is in a different orbit, a Hubble crew would not be able to reach the space station in an emergency.

Read our update story.

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

Piers Sellers and Mike Fossum are busy with the cleanup activities down in the payload bay after today's successful boom tests.

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

The boom stability testing has been completed. The spacewalkers went through the checklist of various tasks and scenarios of inspecting and repairing the shuttle heatshield while using the 50-foot boom as a work platform. The crew is headed back to the payload bay to put away their tools, then they will climb up to the station airlock to end the first of three EVAs on this mission.

1804 GMT (2:04 p.m. EDT)

Mission Control just advised the crew they need to wrap up the tests within the next 20 minutes to ensure they have sufficient time to clean up and end the EVA as scheduled.

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

And now the shuttle arm has moved the boom and its two spacewalker passengers within reach of the P1 truss. This final planned series of tests will practice actual shuttle repair movements, such as simulating applying tile repair material with an applicator, drilling on a wing leading edge panel and using a spatula with repair material on an RCC panel.

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

Now four hours into today's spacewalk. Fossum and Sellers are doing their evaluations at the second test site.

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

This next test sequence occurs 16 feet in front of the station's P1 truss. The configuration puts the arm in a "weaker" state than the earlier tests over the payload bay. Fossum will be doing some of the same actions that Sellers did earlier, then both spacewalkers will move simultaneously to further understand the boom's stability.

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

Both spacewalkers are riding on the end of the boom now. They are being maneuvered up to the Port 1 truss of the space station for the next test location.

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

Astronaut Piers Sellers, his feet anchored to the end of a 50-foot-long boom attached to the shuttle Discovery's robot arm, bobbed about and simulated repair work today in a dramatic test of the space crane's stability for possible use in future shuttle repairs.

With fellow spacewalker Mike Fossum looking on from the shuttle's cargo bay, Sellers went through a scripted sequence of movements - lay backs, rotations, simulated tool retrievals and foot platform relocations - and the long, spindly looking arm/inspection boom combination appeared relatively stable.

It swayed in gentle, slow-motion fashion as Sellers moved about, causing the brakes on the arm's wrist joint to slip at one point. But to the untrained eye, it appeared stable enough to use as a work platform. Whether NASA managers will deem it safe for actual repair work, when an astronaut would be much closer to the shuttle's fragile heat shield, remains to be seen.

Read our update story.

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

The spacewalkers had been wrestling with a tether problem. But it turned out to be a simple fix -- the lock was engaged on the retractor. So the guys are now getting ready to proceed to the next test position.

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

Tests in the first boom position have been completed, and the boom has been lowered back to the payload bay for Sellers to get off.

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

Now Sellers is practicing getting in and out of the foot restraint.

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

Sellers has turned his foot restraint and started doing the motion checks again in this new orientation.

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

The next evaluation involves Sellers getting out of his foot platform. That really made the boom move around. The boom seemed pretty steady in the earlier tasks.

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

Sellers is now laying back and reaching forward to see if those actions induce any motions in the boom.

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

The first action Sellers is doing is taking out a camera and snapping some pictures. The purpose of this test is seeing how much the boom moves while an astronaut is doing such a task, which would be done in shuttle heat shield inspections.

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

"I'm ready," Sellers says. The boom has reached the planned position for the first series of tests over the payload bay.

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

Spacewalker Piers Sells has hopped aboard the Orbiter Boom Sensor System for the first of today's stability tests. The boom, which is attached to the end of the space shuttle's robot arm, will be positioned about 14 feet from the payload bay. That is where Sellers will practice several movements to simulate real inspection or repair actions.

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

Sellers and Fossum are completing the setup chores for the boom tests. They installed a sensor, called the Instrumented Worksite Interface Fixture, that will collect data during the stability tests, and retrieved a pair of 85-foot long safety tethers.

Mission specialists Lisa Nowak and Stephanie Wilson are controlling the shuttle's robotic arm. They brought the boom's tip within reach of the spacewalkers for installation of the sensor package, a portable foot platform and a tool stanchion.

For the first test, Sellers will be riding on the end of the boom while Fossum remains in the payload bay to snap photos.

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

"Hey Piers, take a second and look at the Earth here," pilot Mark Kelly called from Discovery's flight deck a few moments ago. "I think you've got Ireland and England coming up there."

"My left? Oh!" Sellers exclaimed.

"Wow," said Fossum.

"Oh my goodness. It's a beautiful day in Ireland!"

"Indeed it is."

"So to everybody in Ireland, hello!," Sellers said. "You look beautiful today."

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

Now down inside the payload bay of space shuttle Discovery, the astronauts are busy rounding up the tools and equipment needed for the upcoming boom tests. Everything has been going very smoothly in today's spacewalk -- the fourth in Sellers' career and first for Fossum.

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

The spacewalkers climbed to the pressurized mating adapter between the Unity node and Zarya module of the space station to retrieve an articulating portable foot restraint (APFR) and a tool stanchion. They are heading down to Discovery' payload bay to begin preparing for the boom stability tests.

1351 GMT (9:51 a.m. EDT)

Mission Control reports that the spacewalkers have managed to install the blade blocker in the station railcar's troubled umbilical system. Once that the cutter was disabled, the crew routed the railcar's zenith cable back through the interface umbilical assembly to reactivate the transporter. The cable had been removed earlier this year by Expedition 12 to ensure it wasn't accidently cut like the nadir cable.

The success by Sellers and Fossum should mean the railcar can move again. Plans call for it to drive from work site 4 to work site 5 along the station truss so that the spacewalkers can access the nadir cable system for repairs during the second spacewalk Monday.

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

Astronauts PIers Sellers and Mike Fossum, floating in the space station's Quest airlock module, switched their spacesuits to internal battery power at 9:17 a.m. today to officially kick off the first of three planned spacewalks during shuttle Discovery's mission.

The goals of today's six-and-a-half-hour excursion are to begin the repair of a stalled transporter on the station's solar array truss and to test the stability of a 50-foot-long boom attached to the end of the shuttle's robot arm for possible use as a work platform.

This is the 66th spacewalk devoted to space station assembly and maintenance since construction began in 1998. Going into today's spacewalk, 57 U.S., Russian, French, Japanese and Canadian astronauts had logged 390 hours and 54 minutes of EVA time working on the station. Sellers participated in three space station spacewalks in 2002 totaling 19 hours and 41 minutes. Fossum is making his first EVA and thus pushes the number of station spacewalkers to 58.

The first task today is to restore the station's stalled crane transporter platform to limited operation in preparation for a complex repair job during the crew's second spacewalk Monday.

Read our full story.

1318 GMT (9:18 a.m. EDT)

Depressurization is complete and the hatchway to space is open. The official start time for today's spacewalk was called at 9:17 a.m. when the spacesuits were switched to internal battery power.

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

Astronauts Piers Sellers and Mike Fossum are gearing up for a dramatic six-and-a-half-hour spacewalk today to test Discovery's robot arm and a long inspection boom as a potential platform to make heat shield repairs down the road.

First Sellers and then both spacewalkers will secure themselves to the end of the 50-foot-long orbiter boom sensor system - OBSS - while the shuttle's 50-foot-robot arm moves them from point to point to test the stability of the arm/boom combination. At one point, the boom will be extended some six stories or more from the shuttle's cargo bay.

"The question we want to answer is, can you use the boom as a worksite, as a platform to repairing underneath the orbiter?" shuttle commander Steve Lindsey said in a NASA interview. " So, the scenario is you have a problem, you want to go repair a tile or a leading edge (panel) or something like that. Can you put (one or two spacewalkers) out on the end of this boom, maneuver them underneath the vehicle, and is the platform stable enough to allow them to do repairs?"

Read our spacewalk preview story.

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

Astronauts Piers Sellers and Mike Fossum have donned their spacewalking suits for today's EVA outside the docked space shuttle/station complex. Depressurization of the airlock is now underway.

FRIDAY, JULY 7, 2006

NASA's Mission Management Team today officially approved a one-day mission extension for shuttle Discovery's crew, allowing the astronauts to stage a third spacewalk next week to test wing leading edge repair techniques. Piers Sellers and Mike Fossum plan to stage their first excursion Saturday, starting around 9:13 a.m., to test the ability of a long boom on the end of the shuttle's robot arm to serve as a work platform for future repair work.

With spacewalk preparations in high gear, engineers are still assessing the health of two leading edge panels on Discovery's right wing, along with a protruding gap filler just in front of a propellant feedline access door on the orbiter's belly. Mission Management Team Chairman John Shannon said today it might take another day or two before engineers can either give Discovery a clean bill of health or show the "regions of interest" represent potentially serious problems. While many engineers are optimistic - Discovery appears to be one of the "cleanest" shuttles ever launched - Shannon said he would not speculate on the possible outcome of the ongoing engineering analysis.

Read our full story.

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

With a one-day mission extension considered a done deal, the Discovery astronauts are using a high-resolution camera to inspect a half-dozen areas of the shuttle's heat shield for signs of damage during launch Tuesday. Engineers at the Johnson Space Center, meanwhile, are starting to think about whether the astronauts might need to remove one or two protruding gap fillers during a third spacewalk expected to be added to the mission now that engineers know Discovery will have enough power to support the extra day in orbit. Read our full story.

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

The astronauts opened the hatchway into the Leonardo cargo module at 2:55 p.m., kicking off days of unloading chores. Meanwhile, some of the crew is busy conducting the focused inspections on the nose, wing edges and tile gap fillers of Discovery.

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

Pilot Mark Kelly, Lisa Nowak and Stephanie Wilson are gearing up carry out so-called focused inspections of Discovery's heat shield to double check several areas of interest that were noticed during earlier inspections. Read our full story.

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

Astronauts aboard the international space station, operating the lab's Canadian-built robot arm, gently plucked a 10-ton cargo module from the shuttle Discovery's payload bay today for attachment to the international space station. Read our full story.

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

The Leonardo module has been mounted to the space station. Crews will been opening the hatchway and entering the module through the Unity node later today.

Here is some additional background on the module's cargo from the STS-121 press kit:

Leonardo will carry five resupply stowage platforms (RSPs), three resupply stowage racks (RSRs), one EXPRESS (EXpedite the PRocessing of Experiments to the Space Station) transportation rack (ETR), the European modular cultivation system (EMCS), an oxygen generation system (OGS) rack and the MELFI. The OGS, RSRs and ETR are U.S.-built while the MELFI is provided to NASA by the European Space Agency (ESA) as part of the Columbus orbital facility launch barter agreement.

Utility Logistics Flight (ULF) 1.1 is primarily an ISS crew augmentation mission (a third crew member will arrive on this flight), with the MPLM ferrying more than 5,000 pounds of cargo, a majority of which is food, clothing and crew consumables. The MPLM will have 153 cargo transfer bags (can hold about 1.6 cubic feet per each rectangular-shaped suitcase) to bring supplies into the station. The CTBs are installed in lockers in RSRs in the MPLM and are removed individually by the crew and then stored in the station.

The MPLM will carry two new research facilities; MELFI and EMCS. MELFI is a dedicated rack sized facility while EMCS will be located within EXPRESS Rack No. 2. These two facilities will be installed in the Boeing-built Destiny laboratory.

The EXPRESS rack is a standardized payload rack system that transports, stores and supports experiments aboard the ISS. EXPRESS stands for EXpedite the PRocessing of Experiments to the space station, reflecting the fact this system was developed specifically to maximize the station's research capabilities. With its standardized hardware interfaces and streamlined approach, the EXPRESS rack enables quick, simple integration of multiple payloads aboard the ISS.

The MELFI, which weighs 1,617 pounds, will provide current and future ISS crews with a critical lab freezer capability for maintaining scientific samples and experiments and will ultimately provide greater capability for utilization, life sciences and research.

The EMCS, a 1/2 EXPRESS rack that weighs 655 pounds, is a large incubator that provides control over atmosphere, lighting and humidity of growth chambers. The first planned experiment will use the chamber to study plant growth.

The MPLM will also transport the 1,465 pound OGS rack that uses water to generate breathable oxygen for crew members. The life-support system is considered a test initiative for future long-duration missions to the moon and Mars. The system - which was designed and tested by engineers from Marshall Space Flight Center and from Hamilton Sundstrand Space Systems International in Windsor Locks, Conn. - will replace oxygen lost during experiments and airlock depressurization and can provide up to 20 pounds of oxygen daily - enough to support six station crew members - although it is initially planned to produce about 12 pounds daily.

The MPLM will also carry a new cycle ergometer with vibration isolation and stabilization (CEVIS). CEVIS will give expedition crews on station better aerobic and cardiovascular conditioning through cycling activities. In addition, the MPLM will carry a common cabin air assembly heat exchanger (CCAA HX) used to cool cabin air and maintain a good cabin temperature; it will replace the one currently on orbit.

Used equipment and a small amount of trash will be transferred to Leonardo from the ISS for return to Earth. The Leonardo logistics module will then be detached from the station and positioned back into the shuttle's cargo bay for the trip home. When in the cargo bay, Leonardo is independent of the shuttle cabin, and there is no passageway for shuttle crew members to travel from the shuttle cabin to the module. The total weight of Leonardo for STS-121 with the cargo, platforms and racks is just less than 21,000 pounds for launch and a little over 17,900 pounds for landing.

1015 GMT (6:15 a.m. EDT)

The Multi-Purpose Logistics Module loaded with supplies and equipment is being lifted out of space shuttle Discovery's payload bay this morning for attachment to the International Space Station's Unity connecting node. The module, named Leonardo, is being moved using the station's Canadian-made robot arm. Mission Control announced at 5:42 a.m. that the arm had grappled Leonardo and then confirmed the module was in motion at 6:12 a.m.

Here is some background on the module from the STS-121 press kit:

Leonardo, built by the Italian Space Agency, is the first of three such pressurized modules that serve as the station's "moving vans," carrying laboratory racks filled with equipment, experiments and supplies to and from the ISS aboard the space shuttle.

Construction of the Leonardo module was the responsibility of Altec in Turin, Italy, which is a subsidiary of Alenia Aerospazio. Leonardo was delivered to Kennedy Space Center from Italy in August 1998 by a special Beluga cargo aircraft. The cylindrical module is about 6.4 meters (21 feet) long and 4.6 meters (15 feet) in diameter. It weighs about 9,500 pounds (almost 4.5 metric tons). It can carry up to 10 metric tons of cargo packed into 16 standard space station equipment racks.

Although built in Italy, Leonardo and two additional MPLMs are owned by the U.S. They were provided in exchange for Italian access to U.S. research time on the station. The unpiloted, reusable logistics module functions as a cargo carrier and a space station module when it is flown. To function as an attached station module as well as cargo transport, Leonardo contains components that provide some life support, fire detection and suppression, electrical distribution and computer functions. Eventually, the modules might also carry refrigerator freezers for transporting experiment samples and food to and from the station.

Leonardo first flew to the space station aboard Discovery on STS-102/5A.1 in March 2001. It flew again aboard Discovery on STS-105/7A.1 in August 2001 and aboard Endeavour on STS-111/UF2 in June 2002. Aboard Discovery, STS-121 will be its fourth flight.

THURSDAY, JULY 6, 2006

Preliminary assessment of the shuttle Discovery's heat shield after a dramatic end-over-end flip Thursday while approaching the international space station shows no signs of appreciable damage to the ship's fragile heat shield tiles from debris impacts during launch, officials said. Read our full story.

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

With commander Steve Lindsey at the controls, the shuttle Discovery glided to a smooth, picture-perfect docking with the international space station today as the two spacecraft sailed high above the South Pacific Ocean. Read our full story.

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

HATCHWAY OPENED! Expedition 13 crewmembers Pavel Vinogradov and Jeff Williams are welcoming the seven Discovery astronauts aboard the International Space Station, their first visitors in three months of living aboard the outpost.

The crew members are together and beginning their busy timeline of joint work. After an initial welcoming ceremony, station commander Vinogradov will give a safety briefing. Then German astronaut Thomas Reiter will transfer his seatliner to the Russian Soyuz spacecraft docked to the station to signify the official transfer from the shuttle crew to the station Expedition 13 long-duration crew.

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

The docking ring between the two craft has been retracted into Discovery's Orbiter Docking System, pulling the station to a tight mating. And now the hooks and latches have driven shut to firmly connect the two spacecraft.

Pressure and leak checks will be performed by the crews before the hatchway is opened.

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

Docking occurred right on time over the South Pacific west of Chile.

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

CONTACT AND CAPTURE! Discovery has arrived to the International Space Station, docking with the outpost to deliver fresh supplies, equipment and a third member for the resident crew.

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

The opening of hatches between the station and shuttle is expected in about two hours. That will be followed by a welcoming ceremony and safety briefing.

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

The spacecraft now moving into orbital sunrise.

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

Ten feet to go. Discovery's thrusters are programmed to fire in a post-contact maneuver to force the two docking ports together. That procedure is now armed and ready.

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

Discovery is 20 feet from docking. Commander Steve Lindsey is piloting Discovery from the aft flight deck controls.

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

The alignment between docking ports on Discovery and the space station is acceptable and no "fly out" maneuver by the shuttle is necessary.

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

Inside 40 feet from docking.

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

Now 50 feet separating Discovery from the station.

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

Less than 75 feet to go.

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

The shuttle is approaching to the station's front docking port along the velocity vector. Distance is less than 100 feet.

1431 GMT (10:31 a.m. EDT)

Discovery is 135 feet from the docking port, closing at 0.14 feet per second.

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

Now 160 feet from docking. Discovery is closing at about a tenth-of-a-foot per second.

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

The station crew has started to downlink the digital images of Discovery.

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

The shuttle is 300 feet from the docking port.

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

The spacecraft are moving into orbital sunset now. The astronauts will see sunrise at 10:51 a.m.

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

Discovery has reached the point directly in front of the station along the imaginary line called the velocity vector, or +V bar.

1409 GMT (10:09 a.m. EDT)

The shuttle is about halfway through its trek from below the station to a point directly in front of the orbiting complex.

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

Shuttle flight director Tony Ceccacci has given the "go" for docking.

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

Discovery is making an arc from the point below to a point 400 in front of the space station to align with the docking port on the Destiny module.

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

Discovery is back in the orientation where it started, with the payload bay looking up at the station. The Rendezvous Pitch Maneuver has been completed.

1357 GMT (9:57 a.m. EDT)

The main engine nozzles of Discovery are facing the station now as the shuttle points its tail upward.

1356 GMT (9:56 a.m. EDT)

The shuttle is 180 degrees into this complete 360-degree flip.

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

The shuttle is rotating at three-quarters of a degree per second.

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

This 360-degree, nose-first pirouette by Discovery has rotated the belly of the shuttle into view of the space station for the ISS crew to snap detailed pictures of the orbiter's black tiles in the search for any launch impact damage.

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

Discovery's nose is now pointed directly at the space station.

1352 GMT (9:52 a.m. EDT)

The two craft are flying 209 miles above Spain.

1351 GMT (9:51 a.m. EDT)

The Rendezvous Pitch Maneuver has begun.

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

One minute till the RPM, the Discovery crew advises.

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

It is now orbital noon for two spacecraft.

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

Discovery is 650 feet below ISS. Now five minutes until the RPM starts.

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

Shuttle is now 800 feet beneath the station. The lighting window to do the backflip maneuver opens in about 10 minutes.

1338 GMT (9:38 a.m. EDT)

Discovery is arriving on the R-bar, the imaginary line from the station down to Earth. Distance between the shuttle and station is now 1,000 feet.

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

The spacecraft are flying less than 2,000 feet apart some 220 miles above South America. Time to docking is under 90 minutes now.

On final approach, at a distance of about 600 feet directly below the station, commander Steve Lindsey will carry out a slow 360-degree rendezvous pitch maneuver, or RPM, that will point the belly of the shuttle at the station.

As the shuttle's underside rotates into view, the station's two residents, Expedition 13 commander Pavel Vinogradov and flight engineer Jeff Williams, shooting through windows at opposite ends of the station, will photograph Discovery's belly with handheld digital cameras equipped with 400- and 800-millimeter lenses.

The 800mm images should provide one-inch resolution for examination of landing gear door seals and protruding tile gap fillers. The 400mm will yield three-inch resolution.

After completing the RPM maneuver, Lindsey will position Discovery directly ahead of the space station with the shuttle's nose facing deep space and its cargo bay pointed at the lab complex. He then will guide the spacecraft to a docking with a pressurized mating adapter attached to the Destiny lab module.

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

The fourth course correction burn was just conducted.

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

Discovery now about 3,300 feet from the station.

1319 GMT (9:19 a.m. EDT)

The third course correction burn has been successful. And a video camera aboard the space station actually saw the white plumes from the jet thrusters firing.

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

The shuttle is now 5,500 feet from the station, closing at about 7 feet per second. That closure rate will gradually slow and then be stopped once Discovery gets to a point inside 1,000 feet directly below the station for the pitch maneuver to present the belly to the station crew for photography.

1303 GMT (9:03 a.m. EDT)

Another good course maneuver was just performed.

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

Discovery has closed to within 21,000 feet now.

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

The latest revision of the NASA Television schedule is available here.

Also, the master flight plan has been updated here. And today's rendezvous day timeline has been posted.

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

The shuttle and station crews have established direct radio communications.

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

Now 41,000 feet separating the two spacecraft.

1225 GMT (8:25 a.m. EDT)

Discovery has performed the first of several mid-course correction burns available during the approach this morning.

1212 GMT (8:12 a.m. EDT)

The space station crew reports it spotted the approaching Discovery from a distance of about 50,000 feet.

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

TI burn. With about nine miles separating Discovery and the space station, the shuttle has fired its left OMS engine for the Terminal Initiation maneuvering burn to begin the final phase of this morning's rendezvous.

The TI burn puts the shuttle on a trajectory to directly intercept the orbiting station over the next orbit and a half. This burn is the latest in a series of maneuvers performed by Discovery during its two days of chasing the station since launch Tuesday.

Docking is set for 10:52 a.m. EDT.

1145 GMT (7:45 a.m. EDT)

The shuttle Discovery is closing in on the international space station today for a long-awaited linkup that will boost the lab's crew size to three, provide more than 5,000 pounds of equipment and supplies and give mission managers their first detailed view of the fragile heat shield tiles on the shuttle's belly.

"Good morning, Discovery!" mission control told the crew in a morning uplink package. "Great day yesterday, finishing flight day 2 early, that's amazing. As for today, just a rendezvous. However, you will be losing a crewmember at the end of the day, but then again, you're gaining a Station."

European Space Agency astronaut Thomas Reiter will remain aboard the station when Discovery departs, boosting the lab's crew size to three for the first time since downsizing in the wake of the Columbia disaster.

In the morning "execute package" uplinked to the shuttle crew, flight controllers passed on a detailed update from NASA's Mission Management Team on what engineers have seen so far assessing video, radar data, still images and data from wing leading edge impact sensors during launch Tuesday:

full story.

WEDNESDAY, JULY 5, 2006

After a full day of image analysis and inspections, NASA engineers are increasingly optimistic that major changes to the foam insulation on the shuttle Discovery's external fuel tank worked as required to minimize the release of potentially catastrophic debris during the ship's Fourth of July climb to space.

If they're right, and if preliminary indications are confirmed during continued observations and around-the-clock analysis, NASA will move a major step closer to putting its painful post-Columbia return-to-flight effort behind it, shifting the focus instead to resuming assembly of the international space station.

"We have in hand all the data we're going to get from the external tank and the performance was very good," said John Shannon, chairman of NASA's Mission Management Team. "And we got some good data, too, which was really important. We really want to be able to verify what kind of redesigns we were doing."

Read our full story.

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

The Discovery astronauts carried out painstaking, inch-by-inch inspections of the shuttle's carbon composite nose cap and wing leading edge panels today, using a laser sensor on the end of a long boom to look for signs of ascent impact damage. White markings thought to be bird droppings were spotted at one point, and a few other whitish streaks were visible, but no obvious signs of significant damage were seen in downlinked TV. Read our full story.

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

Discovery's astronauts have wrapped up the initial scans of the heatshield using the 50-foot inspection boom. The final portion of those activities today was the port wing leading edge. The boom is being returned to its cradle in the payload bay. The shuttle's robot arm will examine the upper surfaces of the orbiter via its camera as the day goes on.

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

The nose cap examinations are complete, and the astronauts have set up the centerline camera in the docking port that will help commander Steve Lindsey during approach to the space station tomorrow. Also, the docking ring has been extended into position for capture with the station.

The inspection data has to be downlinked to the ground for analysis. So it is too early for any conclusions about what has been observed.

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

Inspections of the starboard wing of space shuttle Discovery using the laser and camera package on the Orbiter Boom Sensor System were performed this morning. The crew is now beginning inspections of the ship's nose cap.

1200 GMT (8 a.m. EDT)

Discovery's astronauts are awake and ready to begin their first full day in space. Today the crew will focus on thermal protection system inspections, preparing for docking to the International Space Station and getting spacesuits ready for two and perhaps three spacewalks.

Commander Steve Lindsey, Pilot Mark Kelly and Mission Specialists Mike Fossum, Lisa Nowak, Stephanie Wilson, Piers Sellers and Thomas Reiter got their wakeup call at 5:08 a.m. EDT, allowing them an extra 30 minutes of sleep after their first day in space ran long. The wakeup song was "Lift Every Voice and Sing" performed by the New Galveston Chorale.

See the latest Mission Control Center status report.

TUESDAY, JULY 4, 2006

The shuttle Discovery's external tank lost only small pieces of foam insulation during launch today, and those were well after the period when aerodynamic effects can lead to dangerous impacts with the orbiter, officials said late today. Read our full story.

2359 GMT (7:59 p.m. EDT)

On the nation's 230th birthday, Discovery rocketed into the Florida sky this afternoon, returning the shuttle fleet to space after almost a year. The first human spacecraft to launch on an Independence Day holiday, Discovery has begun a journey to resupply and service the International Space Station. See the Mission Control Center status report No. 1.

2353 GMT (7:53 p.m. EDT)

There were five foam shedding events during launch, Hale says, but they all appeared "minor" and after the critical time during ascent through the atmosphere when such debris could damage the orbiter.

2350 GMT (7:50 p.m. EDT)

The object seen by astronaut Mike Fossum undoubtedly is ice, Hale says.

2341 GMT (7:41 p.m. EDT)

"I think the tank performed very well," shuttle program manager Wayne Hale says at the imagery news conference now underway at KSC.

2210 GMT (6:10 p.m. EDT)

Astronaut Mike Fossum, photographing the shuttle Discovery's external fuel tank as it tumbled away in space, told flight controllers today that he also noticed what appeared to be a large piece of debris, presumably from the shuttle itself, floating away in space. Read our full story.

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

The space shuttle Discovery and its flag-waving crew thundered into space today, putting on a spectacular Fourth of July skyshow as it rocketed away on a long-awaited mission to repair and resupply the international space station. Read our full story.

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

NASA officials are stressing that it will take some time to analyze the video and film footage and no one should jump to conclusions about what was seen.

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

Shuttle program manager Wayne Hale says the very preliminary look at the onboard video from the external fuel tank shows three or four pieces of debris coming off the tank at T+plus 2 minutes, 47 seconds. It could be an ice-frost ramp or something else, he said.

More debris was noted about T+plus 4 minutes, 50 seconds.

Hale noted that both events occurred after the time debris striking the orbiter could cause damage because the vehicle was out of the atmosphere.

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

T+plus 45 minutes, 30 seconds. Discovery has achieved an orbit of 143 by 97 statute miles.

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

T+plus 42 minutes, 30 seconds. A quick review of video shows small pieces of debris shedding from the external fuel tank about three minutes after liftoff.

1917 GMT (3:17 p.m. EDT)

T+plus 39 minutes, 20 seconds. The twin Orbital Maneuvering System engines on the tail of Discovery have been fired successfully to propel the shuttle the rest of the way to orbit.

1916 GMT (3:16 p.m. EDT)

T+plus 38 minutes, 18 seconds. The maneuvering engines have ignited for the orbit raising burn.

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

T+plus 37 minutes, 30 seconds. Discovery has oriented itself into the upcoming OMS engine firing and the shuttle is reported in a good configuration for the burn.

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

T+plus 22 minutes. The two flapper doors on the belly of Discovery are being swung closed to shield the umbilicals that had connected to the external fuel tank.

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

T+plus 16 minutes, 45 seconds. The OMS engine burn to insert Discovery into orbit will begin at T+plus 38 minutes and 0 seconds.

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

T+plus 14 minutes, 40 seconds. The "go" has been given to the crew for APU shutdown as planned.

1851:55 GMT (2:51:55 p.m. EDT)

T+plus 14 minutes. Discovery has reached a preliminary sub-orbital trajectory. Coming up, the Orbital Maneuvering System engines will be fired to raise the low point to a safe altitude.

1849 GMT (2:49 p.m. EDT)

T+plus 11 minutes, 30 seconds. Two of Discovery's mission specialists are unstrapping and hurrying into position to image the fuel tank. Mike Fossum will be using a camcorder and Stephanie Wilson will snap pictures with a digital still camera equipped with a with 400mm lense. The footage will be taken from 1450 feet away for later downlink to the ground.

1847 GMT (2:47 p.m. EDT)

T+plus 9 minutes, 30 seconds. Commander Steve Lindsey is maneuvering the orbiter so digitial and film cameras embedded in the umbilical well on the belly of Discovery can photograph the discarded fuel tank.

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

T+plus 8 minutes, 53 seconds. The emptied external tank has been jettisoned from the belly of space shuttle Discovery. The tank will fall back into the atmosphere where it will burn up harmlessly.

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

T+plus 8 minutes, 38 seconds. MECO! Confirmation that Discovery's main engines have cutoff as planned, completing the powered phase of the launch.

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

T+plus 7 minutes, 40 seconds. The main engines beginning to throttle back to ease the force of gravity on the shuttle and astronauts.

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

T+plus 7 minutes, 12 seconds. The ship is 516 miles downrange from the pad.

1844 GMT (2:44 p.m. EDT)

T+plus 7 minutes. Main engines continue to perform well as Discovery nears the completion of powered ascent.

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

T+plus 5 minutes, 59 seconds. The shuttle has started rolling to a heads-up position to improve communications with the TDRS satellite network.

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

T+plus 5 minutes, 25 seconds. Discovery speed has reached 7,000 mph.

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

T+plus 4 minutes, 20 seconds. Discovery is 150 miles northeast of the launch pad at an altitude of 61 miles, traveling at 5,000 mph.

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

T+plus 4 minutes, 5 seconds. Negative return. The shuttle is traveling too fast and is too far downrange so it can no longer return to the launch site in the event of a main engine problem.

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

T+plus 3 minutes, 45 seconds. Discovery is 100 miles northeast of the launch pad at an altitude of 53 miles and traveling over 4,000 mph.

1840:55 GMT (2:40:55 p.m. EDT)

T+plus 3 minutes. Discovery's main engines continue to fire, guzzling a half-ton of propellant per second.

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

T+plus 2 minutes, 20 seconds. Guidance is converging as programmed.

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

T+plus 2 minutes, 8 seconds. The twin solid rocket boosters have done their job and separated from the space shuttle Discovery. The shuttle continues its climb to space on the power of the three liquid-fueled main engines.

1839 GMT (2:39 p.m. EDT)

T+plus 90 seconds. All systems of Discovery are performing well as the shuttle accelerates to orbit on this first American manned spaceflight ever launched on the Fourth of July.

1839 GMT (2:39 p.m. EDT)

T+plus 78 seconds. Discovery's engines have revved back to full throttle. Mission Control has given the "go" at throttle call and commander Steve Lindsey has acknowledged that. No problems have been reported in this afternoon's ascent.

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

T+plus 35 seconds. Discovery's three main engines easing back to two-thirds throttle to reduce the aerodynamic stresses on the vehicle as it powers through the dense lower atmosphere. The shuttle is using the so-called Low Q ascent mode and will keep the engines at this power setting for 10 seconds longer than usual. Also, Discovery's nose is being pitched up one-a-half degrees higher than the normal angle to reduce the aerodynamic loads on the external fuel tank.

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

T+plus 20 seconds. Houston has assumed control of the mission as the shuttle rolls to the heads-down, wings-level position for climb away from Earth. Discovery is embarking on a northeasterly trajectory up the Eastern Seaboard on the two-day chase to catch the orbiting International Space Station, which is currently flying half-a-world away south of Tasmania above the southern Pacific Ocean.

1837:55 GMT (2:37:55 p.m. EDT)

LIFTOFF! Liftoff of Discovery on a mission to test the safety improvements for the space shuttle program. And the vehicle has cleared the tower!

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

T-minus 31 seconds. Go for auto sequence start. Control of the countdown has been handed off to the space shuttle.

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

1836:55 GMT (2:36:55 p.m. EDT)

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

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

1835:55 GMT (2:35:55 p.m. EDT)

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

At T-minus 1 minute, 57 seconds the replenishment of the flight load of liquid hydrogen in the external tank will be terminated and tank pressurization will begin.

1835:25 GMT (2:35:25 p.m. EDT)

T-minus 2 minutes, 30 seconds. The external tank liquid oxygen vent valve has been closed and pressurization of the LOX tank has started.

Discovery's power-producing fuel cells are transfering to internal reactants. The units will begin providing all electricity for the mission beginning at T-50 seconds.

And pilot Mark Kelly has been asked to clear the caution and warning memory system aboard Discovery.

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

1834:55 GMT (2:34:55 p.m. EDT)

T-minus 3 minutes. Orbiter steering check now complete -- the main engine nozzles are in their start positions.

1834:25 GMT (2:34:25 p.m. EDT)

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

1833:55 GMT (2:33:55 p.m. EDT)

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

1832:55 GMT (2:32:55 p.m. EDT)

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

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

1832:25 GMT (2:32:25 p.m. EDT)

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

1831:35 GMT (2:31:35 p.m. EDT)

T-minus 6 minutes, 20 seconds. Pilot Mark Kelly has been asked by Orbiter Test Conductor Rudy Tench to pre-start the orbiter Auxiliary Power Units. This procedure readies the three APU's for their activation after the countdown passes T-minus 5 minutes.

1830:25 GMT (2:30:25 p.m. EDT)

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

1829:55 GMT (2:29:55 p.m. EDT)

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

1828:55 GMT (2:28:55 p.m. EDT)

T-minus 9 minutes and counting. The ground launch sequencer is now controlling the final phase of today's countdown to launch of space shuttle Discovery at 2:37:55 p.m. EDT. The GLS will monitor as many as a thousand different measurements to ensure they do not fall out of predetermine red-line limits.

1827:55 GMT (2:27:55 p.m. EDT)

Now 10 minutes from launch of Discovery.

1826:55 GMT (2:26:55 p.m. EDT)

Countdown clock will resume in two minutes.

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

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

NASA launch director Mike Leinbach has finished his final poll. He has wished commander Lindsey and crew good luck and God speed. Launch is set for 2:37:55 p.m.

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

NASA launch director Mike Leinbach is conducting his poll.

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

The final readiness poll of the launch team by NASA test director confirms there are no technical issues being addressed.

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

Weather officials say all conditions currently observed and forecast for launch are acceptable!

1817 GMT (2:17 p.m. EDT)

Mission Management Team chairman John Shannon has polled his team for a readiness call to proceed with the countdown. No constraints were reported.

1807:55 GMT (2:07:55 p.m. EDT)

Now 30 minutes away from launch time.

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

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

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

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

Engineers report there is a potential for the liquid oxygen inlet temperature to be slightly too warm late in the countdown. The plan to remedy the situation, if it happens, is hold the clock at T-minus 31 seconds for about a minute to let the normal liquid oxygen drainback cool the temperatures to within limits.

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

Now 30 minutes remaining in this hold.

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

The launch window closure time has been adjusted slightly to 2:41:36 p.m. EDT. That is the last second Discovery can lift off today or else wait till tomorrow.

1752 GMT (1:52 p.m. EDT)

Launch of Discovery remains targeted for 2:37:55 p.m. EDT.

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

T-minus 9 minutes and holding. Countdown clocks have gone into the planned 45-minute, 55-second built-in hold. Today's launch remains set for 2:37:55 p.m. EDT. There are no significant technical problems being reported and the crosswinds at the Shuttle Landing Facility are being watched.

1738 GMT (1:38 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.

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

T-minus 15 minutes. Now one hour away from launch of Discovery.

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.

1732 GMT (1:32 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 2:37:55 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.

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

The launch team has been briefed on today's launch window and countdown procedures. Standing by to resume the clock momentarily.

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

T-minus 20 minutes and holding. The countdown has paused for a 10-minute built-in hold. Launch remains scheduled for 2:37:55 p.m. EDT.

All weather conditions remain "go" at this time. Crosswinds at the launch site's emergency runway that would be used if Discovery aborts the mission could be an issue. The winds cannot exceed 17 knots.

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.

1715 GMT (1:15 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 2:34:26 p.m., with the desired liftoff time of 2:37:55 p.m. The window closes at 2:41:39 p.m.

1710 GMT (1:10 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.

1709 GMT (1:09 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.

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

A good seal on Discovery's crew hatch is confirmed, the cabin is pressurized for flight and the pressure checks have been completed. The Orbiter Closeout Crew is departing the pad now. "We're outta here."

1704 GMT (1:04 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.

1700 GMT (1:00 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.

1642 GMT (12:42 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.

1633 GMT (12:33 p.m. EDT)

Pressure and leak checks will be performed to ensure a good seal on the hatch for today's launch.

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

The crew module hatch has been sealed and latched for flight, the closeout crew reports.

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

The hatch is now swinging shut.

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

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

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

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

1612 GMT (12:12 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 2:37:55 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.

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

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

1554 GMT (11:54 a.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.

And a video interview with Nowak is available here.

1543 GMT (11:43 a.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.

And a video interview with Sellers is available here.

1541 GMT (11:41 a.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.

And a video interview with Fossum is available here.

1537:55 GMT (11:37:55 a.m. EDT)

Launch of Discovery is now three hours away.

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

Mission specialist No. 3 Stephanie Wilson is now aboard Discovery. 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.

And a video interview with Wilson is available here.

1525 GMT (11:25 a.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.

And a video interview with Kelly is available here.

1516 GMT (11:16 a.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.

And a video interview with Reiter is available here.

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

As skipper of the spacecraft, commander Steve 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.

And a video interview with Lindsey is available here.

1511 GMT (11:11 a.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.

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

The Discovery astronauts have ascended up to the 195-foot level of the tower.

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

Discovery's crew arrived at launch pad 39B at 11:07 a.m. The AstroVan 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.

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

The convoy has made the left turn from the crawlerway to head northward for pad 39B.

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

The AstroVan just passed 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.

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

Waving small flags on this Fourth of July, commander Steve Lindsey and his six fellow crewmates just walked out of 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.

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

The latest weather update briefing shows today's odds of acceptable conditions at launch time remain at 80 percent. The outlook for Wednesday and Thursday indicates 40 percent "go" both days.

1442 GMT (10:42 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 2:37:55 p.m. EDT launch time.

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

Space shuttle Discovery is fueled, the astronauts are getting ready to head for the launch pad and countdown clocks remain on schedule for this patriotic Fourth of July liftoff. Today's launch time is 2:37:55 p.m. EDT (1837:55 GMT).

An American manned spaceflight has never launched on Independence Day before. But there was one other notable shuttle program milestone achieved on America's birthday. Back in 1982 Columbia landed at Edwards Air Force Base to cap the fourth and final developmental test flight for the space shuttle. President and Mrs. Reagan were in attendance.

More recently in the U.S. space program, NASA's Mars Pathfinder and the comet-hitting Deep Impact missions reached their cosmic destinations on this date in 1997 and 2005, respectively.

1424 GMT (10:24 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 10:48 a.m. EDT.

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

Another weather issue that will be watched closely toward is crosswinds at the Shuttle Landing Facility for a possible Return to Launch Site abort.

1357 GMT (9:57 a.m. EDT)

The Final Inspection Team is wrapping up its checks of the shuttle. The team members report Discovery looks to be in great shape for liftoff.

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

All of the weather rules are back in "go" status after a shower moved clear of the pad area.

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

Officials have decided against sending a repair crew to the launch pad to address the backup solid rocket booster heater circuit breaker problem. The system can work on the primary circuit breaker system. And obviously it is very warm outside today anyway.

1342 GMT (9:42 a.m. EDT)

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

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

In addition to the cumulus cloud rule, the debris cloud and flight through precipitation rules have gone into violation now.

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

The Final Inspection Team is continuing its work at pad 39B. The 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.

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

The cumulus cloud rule just went red or "no go." We're seeing a lot of cloudiness drift onshore from the Atlantic, plus the development of clouds and some showers inland as well.

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

Discovery's seven astronauts are gathered around the dining room table in crew quarters for a pre-launch snack and the traditional pre-launch photo opportunity.

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.

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

Over the past few minutes, a technical problem has arisen in the countdown with the 100 amp circuit breaker that control all of the heaters on the solid rocket booster joints. A special red team is being assembled for deployment to the launch pad for troubleshooting. The circuit breaker panel is located on the mobile launch platform.

The problem has taken down the backup capability for the heaters, although the system is still operational on the primary side. NASA would like to have full redundancy and there is time in the countdown to do the repair now.

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

The Final Inspection Team observed no ice or frost on the liquid oyxgen feedline support bracket where the foam broke away Sunday.

"So that is good news that there has not been any ice buildup in that area where the insulation was lost or on that feedline bracket," NASA spokesman Geoge Diller says.

1155 GMT (7:55 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 astronauts' arrival about three hours from now.

1153 GMT (7:53 a.m. EDT)

The inspectors are located on the 135-foot level of the Fixed Service Structure of the launch pad to examine the liquid oyxgen feedline support bracket that lost a small piece of foam after Sunday's countdown. The team is looking to see if any ice has formed in that divot.

1145 GMT (7:45 a.m. EDT)

The Final Inspection Team team has arrived at pad 39B along with the Orbiter Closeout Crew, which is the team that will assist the astronauts during boarding.

1142 GMT (7:42 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.

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

The weather rules that were being violated for a short time this morning while a rainshower passes by pad 39B are now back in "go" status.

The launch time forecast calls for scattered clouds at 3,000 feet, visibility of 7 miles, easterly winds from 070 degrees at 11 gusting to 16 knots at the pad, a temperature of 82 degrees F, relative humidity of 79 percent and possible showers in the area.

Meteorologists are setting the odds of acceptable weather for the 2:38 p.m. launch time at 80 percent "go."

1129 GMT (7:29 a.m. EDT)

Filling of Discovery's external fuel tank was called complete at 7:28 a.m. EDT. The tank has been pumped full with 528,000 gallons of supercold liquid oxygen and liquid hydrogen. The process started at 4:33 a.m.

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.

1128 GMT (7:28 a.m. EDT)

Liquid oxygen has gone into replenish mode, completing the external tank filling for launch.

1126 GMT (7:26 a.m. EDT)

The liquid hydrogen tank is now fully loaded. The system has entered into replenish mode to keep the tank topped off through the rest of the count.

1122 GMT (7:22 a.m. EDT)

Fast-fill of the liquid oxygen tank just concluded. Topping of the tank is beginning. On the hydrogen side of things, loading continues.

1118 GMT (7:18 a.m. EDT)

Initial checks of the main engine controllers and the pyro controllers for the solid rocket boosters have been completed.

1105 GMT (7:05 a.m. EDT)

No leaks or concentrations of liquid oxygen or liquid hydrogen have been detected in the shuttle's aft compartment during fueling this morning. And the engine cutoff sensors that were a source of trouble during the last mission are operating normally today.

1055 GMT (6:55 a.m. EDT)

Testing of the space shuttle main engine controllers is now beginning in the countdown.

A small rainshower moving from the Atlantic Ocean is passing near launch pad 39B. That has meant the cumulus cloud, disturbed weather and flight through precipitation weather rules have gone red temporarily while the shower drifts by.

The weather forecast for launch time this afternoon calls for an 80 percent chance of favorable conditions.

1030 GMT (6:30 a.m. EDT)

Good morning from Kennedy Space Center for this Fourth of July launch of space shuttle Discovery. This third countdown attempt is going well so far, with fueling of the external tank about two-thirds complete. The start of fueling was officially clocked at 4:33 a.m. EDT.

0915 GMT (5:15 a.m. EDT)

The fueling activities are continuing as planned this morning. NASA is not reporting any troubles in the countdown.

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.

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).

0838 GMT (4:38 a.m. EDT)

FUELING UNDERWAY. The filling of space shuttle Discovery's external fuel tank with a half-million gallons of supercold propellants has begun at launch pad 39B. The tanking operation commenced with the chilldown thermal conditioning process. That will be followed by the slow-fill mode to initially start loading the respective liquid oxygen and liquid hydrogen tanks within the giant external tank. Fueling then transitions to the fast-fill.

0820 GMT (4:20 a.m. EDT)

The Mission Management Team met for its standard pre-fueling meeting at 3:30 a.m. this morning and gave the approval to begin loading space shuttle Discovery's external tank as planned. The three-hour fueling process is expected to begin in about 25 minutes.

The weather forecast has improved dramatically for today's 2:37:55 p.m. EDT launch opportunity. Meteorologists are predicting an 80 percent chance of acceptable conditions. Rainshowers will be the main area of concern.

0500 GMT (1:00 a.m. EDT)

NASA managers Monday night decided to press ahead with a Fourth of July launch of the shuttle Discovery, weather permitting, after engineers concluded the loss of foam insulation from an external oxygen feedline posed no threat to the orbiter or its crew. Read our full story.

0112 GMT (9:12 p.m. EDT Mon.)

NASA mission managers tonight deemed the foam on the external fuel tank is acceptable for launch on Tuesday.

Three issues that need to be examined were aerodynamic heating on the bracket during launch, ice formation where the piece of foam came off and whether hands-on inspection was needed.

Bill Gerstenmaier, a NASA associate administrator from Washington, said there is a safety factor of five for ascent aerodynamic heating, ice formation should not be a concern because enough foam remains on the structure and technicians were able to get a better look at the area late today after constructing an 8-foot plastic pipe with a camera on the end to get within a foot-to-six inches of the bracket for upclose inspection and to confirm no further cracks.

0037 GMT (8:37 p.m. EDT Mon.)

Sources indicate NASA has cleared space shuttle Discovery for launch at 2:37:55 p.m. EDT on Tuesday. A news conference is coming up at the top of the hour.

0031 GMT (8:31 p.m. EDT Mon.)

NASA is planning a news conference at the conclusion of the management team meeting to announce what the plan will be. That briefing is now expected no earlier than 9 p.m.

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

The management team is still meeting at Kennedy Space Center to review the findings by teams of engineers studying the loss of one tiny piece of foam from Discovery's external tank.

If officials give the OK to proceed with a Tuesday afternoon liftoff, retraction of the rotating service structure from around Discovery will occur within short order this evening. Filling of the external tank would begin around 4:30 a.m.

Read our earlier status center coverage.



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