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 Ke