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For 1 a.m. EST Thursday, March 8

Discovery countdown gets serious

Well, here we go again!

We've barely taken a breath from the conclusion of Atlantis' STS-98 mission -- the orbiter just made it back to Florida on Monday -- and now we're following the countdown to launch of shuttle Discovery at 6:42 a.m. EST today, if all goes well.

And so far it is.

Launch team engineers began filling Discovery's external tank with its half-million gallons of liquid hydrogen and liquid oxygen at 9:30 p.m. EST Wednesday and the process was completed about three hours later. Now fully fueled with its supercold propellant, an ice inspection team is at the launch pad making sure there are no problems.

Discovery crewmembers depart for pad

The seven crewmembers of shuttle Discovery are on their way to launch pad 39B at the Kennedy Space Center.

Wearing their bright orange launch and entry suits, the six men and one woman were all smiles as they made their final pre-flight public appearance departing from the Operations and Checkout Building.

A large group of news media recorded the event, including a team from IMAX who shot the event with a 3D camera from the perspective of a crane sitting several feet above the whole scene.

It will take the astronauts about 20 minutes to reach the pad, another five to get to the top and then about an hour for all seven to board Discovery and get strapped into their seats.

The countdown continues to go well. No technical problems have been reported and the weather appears it will cooperate. A light frost growing on the external tank is not expected to be an issue -- something we've seen before.

Our next update will come when Discovery's hatch is closed for flight.

Shuttle hatch closed for flight

The effort to launch Discovery to the International Space Station this morning is proceeding right on schedule and with no technical or weather-related problems reported.

The seven crewmembers who make up the STS-102 team are onboard Discovery and the shuttle hatch was reported closed and locked for flight at 4:31 a.m. EST. Checks of the crew cabin for air leaks will now begin, a routine task conducted before every launch.

Of note this morning are the views seen on NASA TV of Discovery's external tank, which is growing a noticeable layer of frost. The supercold propellant inside combined with the chilly temperatures over Central Florida right now is turning the tank a little white. Engineers are keeping an eye on this and will become concerned only if they spot layers of ice forming.

Indeed, frost is not a problem and we've seen several examples of the tank turning almost completely white by frost without causing any trouble for a safe launch and mission. Again, the concern being that if the frost became a sheet of ice that could damage the shuttle's heat protection tiles if shaken loose at launch.

With the launch countdown proceeding quietly to a 6:42 a.m. EST liftoff, our next update will come at 6 a.m. EST unless events warrant an earlier report.

Discovery ready to fly

A very quiet countdown and perfect weather offer signs that shuttle Discovery will be able to launch right on time at 6:42:09 a.m. EST.

The launch window will close at 6:47:08 a.m. EST.

All systems are go for launch, so our next update will hopefully come around 7 a.m. EST, after Discovery has launched and safely arrived in orbit.

Shuttle Discovery safely arrives in orbit

Shuttle Discovery has safely arrived in orbit after a spectacular sunrise launch that rivalled the impressive show sistership Atlantis put on in February when it launched just after sunset.

Discovery lifted off at 6:42:09 a.m. EST, right on time after a countdown in which no significant technical issues were ever mentioned and weather cooperated with clear skies and chilly -- but acceptable -- temperatures.

With the crew in orbit they will doff their launch suits and settle in for the stay in space. Docking is the next major event of the mission, scheduled for early Saturday morning at 12:32 a.m. EST.

In the meantime be sure and read Todd Halvorson's launch story and then check back here later in the day for updates on the mission.

Shuttle crew moves through docking preps

It's been an extremely quiet day in orbit as the seven-member crew step through what has become the standard set of day-after-launch procedures for a space station mission.

The robot arm has been checked out and used to inspect the cargo bay, initial checks and tests of the spacesuits that will be worn during the spacewalks were completed, launch equipment has been stowed and other supplies unpacked in anticipation of the docking.

Meanwhile, the maneuvering jets on Discovery have been fired as planned to keep the shuttle on a proper course that will lead to the shuttle and the International Space Station docking together just after midnight early Saturday.

For a complete picture of the events on this first full day in space for the crew, read this story from our Cape Canaveral Bureau Chief, Todd Halvorson, which we posted about two hours ago.

Discovery on final approach to station

Shuttle Discovery is on its final approach to the International Space Station and is expected to dock with the outpost right on schedule at 12:34 a.m. EST Saturday.

Space Station Alpha was first sighted by the shuttle crew about 8:30 p.m. EST tonight, appearing as a bright star, when it was some 42 miles behind the station.

Then at 10:13 p.m. EST the shuttle's maneuvering engines were briefly fired to officially begin the last maneuver that will allow Discovery to rendezvous with the station. Several small course correction burns are planned and then in a just a little while, at 11:42 p.m. EST, commander Jim Wetherbee is to take manual control of the flying duties and pilot Discovery the final 600 feet in to dock with Alpha.

When Discovery docks with the station the shuttle will be flying with its belly facing the direction of travel and its tail pointed toward Earth. The shuttle will then "back" in toward the forward end of the station, connecting to the Pressurized Mating Adapter that leads into the Destiny science module.

So far all systems remain go for docking with Discovery and Alpha about four miles apart and closing.

Discovery stationkeeping with Alpha

Discovery is about 440 feet away from the International Space Station and holding, its docking expected to be delayed to about 1:13 a.m. EST.

Trouble locking the space station's solar arrays into position held up the docking, but that problem has just been cleared and commander Jim Wetherbee has been given a go for docking.

Space station controllers had to unlatch and then relatch the starboard solar wing to clear the issue, but the second attempt worked fine. The concern involved damaging the station's electricity-generating solar arrays as Discovery's steering jets fired and put pressure on the fragile wings.

With the wings locked that concern went away, although officials were discussing allowing Discovery to dock even if the solar wings were not locked, so long as they were moved to appear edge-on in relation to the shuttle.

Discovery inches in on space station

The docking of shuttle Discovery and the International Space Station now is expected at 1:41 a.m. EST, about an hour later than originally planned.

Discovery commander Jim Wetherbee now is flying the shuttle toward Alpha from a work station on the aft flight deck, manually piloting the spaceplane with the help of navigation aids to keep the two vehicles perfectly aligned.

The delay was the result of initial problems locking down an electricity-generating solar array, one of the two giant solar wings installed on the station late last year. The concern was that if the wing wasn't locked, Discovery's steering jets might damage the hardware if a jet were fired in that direction.

Locking latches were ordered to close but didn't do the job, so they were commanded open again and then closed again with the second time working as required.

Wetherbee was then given a go to proceed in at 12:36 a.m. EST.

Shuttle Discovery joins with Station Alpha

For the eighth time in history a space shuttle is docked to the International Space Station, with Discovery commander Jim Wetherbee offering a flawless performance in piloting the shuttle on its rendezvous and docking maneuver.

Discovery docked with the station at 1:38 a.m. EST as the duo flew 236 miles above the South Pacific.

The event came about an hour later than planned. The reason: short-lived difficulty locking down one of the two giant electricity-generating solar wings on the station. Flight rules dictate the wings be locked so they are not inadvertently damaged by the shuttle's steering jets.

Engineers at Mission Control in Houston, however, were ready to give approval for the docking if the wing could not be locked down -- so long as it was twisted in the right direction to minimize any threat from the shuttle's jets.

The schedule for the rest of the day will slip to the right by an hour, but the order of things will stay the same.

First the main latches between the two ships will be closed and verified locked, and then after the relative motion between Discovery and Alpha is damped out the docking ring on the shuttle will be retracted to help form a hard seal between the two ships.

Pressurization of the seal and leak checks will be made and then the hatches will be swung open about 3:45 a.m. EST. A brief welcome ceremony will be followed by a safety briefing, and then cosmonauts Yuri Usachev and Yuri Gidzenko will swap their Soyuz seat liners officially making Usachev a space station crewmember and Gidzenko a shuttle crewmember.

The Soyuz seat liners are individually tailored devices that go in the Soyuz capsule, which would be used in an emergency to evacuate the station and return the Expedition crew members to Earth.

Here's a docking story from Todd Halvorson and we will update this page again following hatch opening later this morning.

Hatches open and shuttle, station crews meet

The hatches between shuttle Discovery and the space station were opened at 3:51 a.m. EST as the orbiting complex flew just east of Florida.

Following the nearly troublefree docking a couple of hours earlier, smiles and waving through windows turned into handshakes and hugs as the ten crewmembers gathered in the U.S. Destiny science lab to greet one another.

A safety briefing is expected to begin shortly and then cosmonaut Yuri Usachev will move his Soyuz seat liner from Discovery into the escape capsule, a tangible symbol of his joining the station crew. Usachev will command the Expedition Two crew and mission managers want him and Expedition One commander Bill Shepherd to spend as much time together as possible during the next nine days.

In turn, Yuri Gidzenko will move his gear into Discovery and officially become a member of the shuttle crew. This process will repeat two more times during the next week as Jim Voss and Susan Helms join the station roster and Shepherd and Sergei Krikalev move into the shuttle for their ride home.

Next up for the mission will be a spacewalk planned to begin about 11:47 p.m. EST tonight. Helms and Voss will float outside to install some equipment on the station exterior that will lay the foundation for future assembly work during several upcoming shuttle missions.

In the meantime, read this new story from Todd Halvorson.

Spacewalkers set out for 'Big Day' at ISS

The first of two planned spacewalks during Discovery's STS-102 mission at the International Space Station has begun some 235 miles above our home planet.

Astronauts Jim Voss and Susan Helms are wearing their spacesuits and disconnected from the shuttle's power supply at 12:12 a.m. EST to rely on their own batteries and officially signal the start of the seven-hour adventure.

Once clear of Discovery's airlock the pair will execute a busy spacewalk agenda, helping to reposition a docking adapter and installing equipment that is critical for future station assembly work. The tasks are so important that NASA flight director John Shannon calls this the mission's "big day."

The effort is doubly important for Voss and Helms, who are spacewalking outside what will be their new home for the next four months once Discovery pulls away from the outpost in a week. Voss, Helms and cosmonaut colleague Yuri Usachev make up the so-called Expedition Two crew to space station Alpha.

NASA TV coverage of the spacewalk is available here on SPACE.com by clicking here.

And for a full preview of today's spacewalk see Cape Canaveral Bureau Chief Todd Halvorson's latest story, posted at 12:45 a.m. EST Sunday.

Discovery spacewalk behind schedule

In general, all is well in space right now. The spacewalk is slightly more than half-way into its planned seven-hour duration, having begun at 12:12 a.m. EST today.

However, replacing a piece of lost equipment and troubles with a sticky connector have put this morning's spacewalk about an hour behind schedule, prompting mission managers to re-arrange the agenda so that high-priority tasks still can be accomplished today.

Soon after entering the cargo bay a portable attachment device was accidentally released into space when its tether somehow released. Astronaut Jim Voss was right there when it happened but could not reach the device in time.

A spare was retrieved and installed on the shuttle's robot arm and is mostly to blame for the schedule slip in the spacewalk.

Meanwhile, Voss and fellow spacewalker Susan Helms have been busy with other tasks, including disconnecting cables from a pressurized mating adapter that is to be repositioned on the Unity module later this morning.

An early communication system antenna was removed by Voss, clearing the way for the docking adapter to be moved and latched on to that area of the Unity module.

Moving the docking adapter is a high-priority task because the Italian module, dubbed Leonardo, is to be installed on the port where the docking adapter is now. Attaching Leonardo and unloading its supplies into the station is one of the principal goals of Discovery's mission.

To put the timeline back on schedule one of the tasks planned for today will be delayed to the second spacewalk, which is to start late Monday night and continue into early Tuesday.

Spacewalkers back in airlock, standing by

Astronauts Jim Voss and Susan Helms are back inside Discovery's airlock, connected to the shuttle's life support systems, but the airlock remains unpressurized in case the pair must go back outside to assist in the task now under way.

The task: Moving a pressurized mating adapter from one port on the Unity module to another.

The move is necessary because the newly opened port is where the shuttle crew later tonight will install the Italian-built Leonardo supply module to the station. After transferring its five tons worth of content from the module to the station, the crew will place Leonardo back into the shuttle for the return to Earth.

Although the crew is on the timeline for the mission, the spacewalkers were not able to get everything done that was planned. Problems early on in the spacewalk, which began at 12:12 a.m. EST, put the effort behind schedule and prompted mission managers to delay at least one major task to the second spacewalk planned to begin late Monday.

If all goes well with the transfer of the docking adapter Voss and Helms will be ordered to close the airlock hatch and repressurize the area, officially ending the 17th extravehicular activity staged at the orbital outpost.

Meanwhile, here at Kennedy Space Center the shuttle/station complex passed overhead at 5:56 a.m. EST just before sunrise and the scene was nothing short of spectacular. Mostly clear skies were just beginning to lighten, while a nearly full Moon and the planet Mars shone with a little more red than usual thanks to the light smoke of nearby brush fires.

Right on schedule, 235 miles up, the complex appeared as the brightest star in the sky, flying a path over Florida's Space Coast that matched the direction we've seen the shuttle fly many times, namely toward the northeast.

The amazing reality that this strange object in the sky was home to 10 humans was underscored by the fact that we could hear air-to-ground conversations with the spacewalkers and with a shift in our focus see live pictures of the spacewalk on NASA TV through our window.

If you've never seen the station fly overhead, it's an experience that is highly recommended. You can learn to track the space station by using SPACE.com's Starry Night software, or check this NASA page for a list of sighting opportunities where you live.

Spacewalk No. 1 is longest in history

Jim Voss and Susan Helms have closed the outer hatch of Discovery's airlock and are about to repressurize the compartment, completing what turned out to be the longest spacewalk ever in Space Shuttle program history.

The 17th extravehicular activity (EVA) officially began at 12:12 a.m. EST this morning and ended at 9:08 a.m. EST, lasting eight hours and 56 minutes, although Voss and Helms spent about the last two hours of the EVA floating inside the depressurized airlock with their suits hooked up to shuttle life support.

The previous longest spacewalk was during the May 1992 three-person EVA to capture the Intelsat satellite.

The spacewalking pair were on "standby" in case they had to go back outside to help with the effort to reposition a station docking adapter. Although that effort was not required, it did take the shuttle crew a little bit longer than expected to line everything up and install the hardware.

And while the spacewalk was the longest for the log books, it is ironic to note that the crew did not finish all of the tasks planned for today, delaying some of the work to a second spacewalk planned for this mission late Monday night.

But the most important goal of the mission today was completed: moving that pressurized mating adapter from one port of the Unity module to another, clearing the way for the Italian supply module known as Leonardo to be temporarily attached to the station later tonight.

Robot arm limbered up for work ahead

The next major milestone of the STS-102 mission is expected within the next couple of hours as the Leonardo supply module is attached to the International Space Station.

The series of events will start with the shuttle's robot arm grabbing the Italian moving van, then the arm will be used to lift the module above Discovery's cargo bay. Robot arm operator Andy Thomas then will position Leonardo against a port on the Unity module.

Latches will be ordered to close and lock the cylinder in place and then the robot arm will release its grasp on Leonardo and return to its park position.

The area between the hatches of Leonardo and Unity will be pressurized and then checked for air leaks. That will be followed by the hatches being opened and the transfer started of some five tons worth of cargo.

Meanwhile, during the course of the evening, shuttle astronaut Jim Voss will officially move into the space station to begin serving as a memeber of the Expedition Two crew. In exchange, cosmonaut Sergei Krikalev will move from the station to the shuttle Discovery.

Tonight's effort is a little behind schedule while some extra checks are made of the area where Leonardo will be attached to the station. Stay tuned to this page throughout the evening for the latest updates on the effort to connect Leonardo.

Leonardo on the move to space station

Major mission milestones are passing quickly tonight at the orbiting shuttle/station complex.

At 10:15 p.m. EST the hatches between Discovery and Alpha were opened for the second time during this shuttle mission. The doors had to be closed after their initial opening Saturday to facilitate the first spacewalk.

With the hatches open again tonight the first order of business was for shuttle astronaut Jim Voss to move his gear into the station and station cosmonaut Sergei Krikalev to pass his gear into the shuttle. At 11:45 p.m. EST that swap was officially concluded, making Voss a space station crewman and Krikalev a member of the STS-102 crew.

Meanwhile, outside the frontier outpost, the Leonardo module was grabbed by the shuttle's robot arm at 10:37 p.m. EST and unberthed from the cargo bay at 11:10 p.m. EST.

Discovery astronaut Andy Thomas, who is operating the robot arm, then moved the Italian module high over the shuttle's cargo bay and at this time has Leonardo nearly in position against the Unity module of the International Space Station.

Italian module locked in place at Alpha

Mission Control in Houston reports that the Italian supply module dubbed Leonardo was securely attached to the International Space Station at 1:02 a.m. EST.

Discovery astronaut Andy Thomas, with the help of shuttle pilot Paul Richards, operated the robot arm that grappled the aluminum cylinder and slowly moved it from its berth in Discovery's cargo bay to an open port on the Unity node of the space station.

The enclosed area between Leonardo and Unity will be pressurized and checked for leaks, and then a little later this morning, about 7 a.m. EST, the astronauts onboard the station will open the hatches to the supply container.

Beginning late tonight the 10 crewmembers onboard the shuttle/station complex will start moving some five tons of equipment and supplies from Leonardo to Alpha. Then the task executed today will be reversed and Leonardo will be removed from the station early Saturday and stowed back in Discovery's cargo bay for the return to Earth.

Supply containers like Leonardo are needed because some of the major pieces of equipment they carry are too large to fit through the shuttle's airlock hatch and connecting tunnel. The hatches between Leonardo and the station, however, are large enough to handle the oversized cargo.

During Leonardo's installation tonight, astronaut Jim Voss officially became a member of the station crew, taking the place of cosmonaut Sergei Krikalev, who has now joined the shuttle crew.

Tonight's efforts are more than an hour behind schedule, so mission managers are working up a new plan for the rest of the day, now that the major task of the day is concluded.

Preps for second spacewalk continue

Discovery astronauts Andy Thomas and Paul Richards are suiting up for a planned spacewalk tonight in which the pair will continue hooking up cables and other equipment at the International Space Station.

The spacewalk is scheduled to start at 11:47 p.m. EST and last about six-and-a-half hours.

During the extravehicular activity, or EVA, Thomas will be wearing the suit with a broken red stripe, while Richards' suit will have barber-pole style red stripes. Knowing that might come in handy as you watch the spacewalk on NASA TV courtesy of our video feed available here.

As the spacewalk gets under way, crew members inside space station Alpha will continue to unpack the Italian cargo carrier known as Leonardo, which was attached to the station earlier today and will remain there until later this week.

Because of the lower cabin pressure inside Discovery to support tonight's spacewalk, the main hatches between the shuttle and the station are closed right now. Bill Shepherd, Yuri Usachev and Jim Voss are inside the station, while the rest of the STS-102 shuttle crew -- including former Expedition One cosmonauts Yuri Gidzenko and Sergei Krikalev -- are inside Discovery.

Second spacewalk still moments away

Tonight's spacewalk now is expected to begin about 12:10 a.m. EST Tuesday, about 23 minutes later than planned because the effort to prepare for the adventure outside took a little longer than expected.

Astronauts Andy Thomas and Paul Richards will be the spacewalkers. It will be the first spacewalk for both of them.

During the extravehicular activity, or EVA, Thomas will be wearing the suit with a broken red stripe, while Richards' suit will have barber-pole style red stripes. Knowing that might come in handy as you watch the spacewalk on NASA TV courtesy of our video feed available here.

Thomas and Richards begin Discovery spacewalk

Rookie spacewalkers Andy Thomas and Paul Richards have officially begun the second and final extravehicular activity (EVA) planned for shuttle Discovery's mission to the International Space Station.

Start time for this EVA was 12:23 a.m. EST. The spacewalk is expected to last about 6.5 hours.

A variety of tasks are in store for the pair, including some work that couldn't be finished by their colleagues Susan Helms and Jim Voss during a spacewalk early Sunday morning.

For a full preview of what's in store for the spacewalkers, see this story from Cape Canaveral Bureau Chief Todd Halvorson.

Rookie spacewalkers get the job done

Astronauts Andy Thomas and Paul Richards have successfully completed the second spacewalk of STS-102 and are safely inside Discovery's repressurizing airlock.

The 18th spacewalk to be staged at the International Space Station complex lasted six hours and 21 minutes, having begun at 12:23 a.m. EST and finished at 6:44 a.m. EST.

All of the work planned for this extravehicular activity was accomplished, including connecting new equipment and cables to various pieces of hardware outside the outpost and fixing a stuck latch atop the giant solar power tower at the station.

Meanwhile, inside the station work continues to unpack the Leonardo supply module that was berthed at the station early Sunday morning. Some five tons of hardware needs to be removed from the Italian cargo carrier before it is disconnected from the station and placed back inside Discovery's payload bay for the return home to Earth.

For the complete story of this morning's spacewalk, see this update from Cape Canaveral Bureau Chief Todd Halvorson.

Shuttle/Station dodges orbital debris

Discovery commander Jim Wetherbee fired the shuttle's steering jets this morning to move the giant shuttle/station complex into a slightly higher orbit to avoid a piece of space junk that had been accidentally released from Discovery's cargo bay during a spacewalk late Saturday.

In short, they dodged their own debris.

It was another space first for the space station program, a sure sign that humans are spending more time in Earth orbit and creating more opportunities for these kinds of things to happen.

Although the station complex has been maneuvered in the past to avoid other orbital debris, this was the first time that a crew had to steer clear of space junk that had originated during the same flight.

The debris was a small Portable Attachment Device, or PAD. It's a tool holding fixture that connects to a foot restraint platform used during spacewalks to give astronauts somewhere to lock their boots in place. The metal device weighs 10.5 pounds, is 13.5 inches long, 7.5 inches wide and 7.5 inches deep.

Late Saturday astronaut Jim Voss was working at the end of the shuttle's robot arm, very early in the spacewalk, when the PAD came loose and drifted off into space. A spare PAD was retrieved and the spacewalk continued without incident.

Radar tracking systems on the ground picked up the PAD and NASA Flight Director John Shannon reported earlier this week the PAD was eight miles ahead of the orbiting outpost, one mile below and posed no hazard to the crew.

Since then, a series of maneuvers by the shuttle/station complex, along with dumping excess water from the shuttle, contributed to changing the vehicles' orbit such that the PAD started getting closer and appeared to offer a potential threat.

At about 9 a.m. EST this morning the crew was told the PAD was now a mile in front, 200 feet below and closing.

As a result, at 10:12 a.m. EST Wetherbee fired the shuttle's jets in a maneuver that lasted about 47 minutes and raised their orbit enough to avoid any chance of a collision that might damage sensitive equipment on the shuttle or station.

Three such orbit-raising maneuvers were already planned for this mission, the first scheduled to occur tonight after the Discovery crew woke up to start their eighth day in space. Performing the debris avoidance maneuver, as a result, gave Wetherbee the chance to get the first burn out of the way early.

Addition orbit-raising maneuvers are scheduled on Thursday and Friday. When completed, the complex is supposed to be some 8.5 miles higher.

Moving day continues in orbit

It's not as dramatic as a spacewalk or a shuttle docking, but the work going on in space right now and for the next couple of days onboard Discovery and the International Space Station is no less critical to the future success of the program.

Astronauts are moving equipment and supplies between the Italian Leonardo supply module and the frontier outpost and continue to find themselves ahead of schedule.

There is about five tons worth of stuff to move out of Leonardo and into the station, including seven equipment racks for the Destiny science lab which was moved into the station on Wednesday.

Assembling and installing the new equipment will mostly fall to the Expedition Two crew of Yuri Usachev, Jim Voss and Susan Helms -- all three of which are officially on board the station as crewmembers there for the next four months or so.

Discovery mission extended

NASA managers have approved extending shuttle Discovery's mission by one day and now are planning to end the flight at 1 a.m. EST Wednesday, March 21.

The reason: to give the combined shuttle/station crew more time to pack the Italian Leonardo supply module for the return home to Earth.

Unloading the module turned out to go more quickly than planned, but apparently filling the module with garbage and other equipment destined for Earth is taking longer than planned, so the extra day will give the 10 crew members the time they need.

Shuttle mission to get busy again

Astronauts aboard the shuttle Discovery and space station Alpha are taking full advantage of the extra day in space to finish loading the Italian supply module with garbage and other equipment to be returned to Earth.

That work has kept the crew busy and appeared to be quietly routine compared to the more dramatic spacewalks and movement of modules we saw earlier in the mission. But the flight plan will get more action-packed again starting later tonight. Here's a review of the plan:

• Saturday at 10:02 p.m. EST: the Leonardo module will be turned off and its hatch closed.
• Sunday at 12:52 a.m. EST: Leonardo is disconnected from the station.
• Sunday at 1:57 a.m. EST: Leonardo is returned to shuttle Discovery's cargo bay.
• Sunday at 8:27 p.m. EST: Final crew farewell and hatch closing.
• Sunday at 11:32 p.m. EST: Discovery undocks from the station.
• Monday at 9:07 p.m. EST: Shuttle crew starts packing for the return to Earth.
• Tuesday at 9:11 p.m. EST: Payload bay doors are closed.
• Tuesday at 11:51 p.m. EST: Discovery fires braking rockets to fall out of orbit.
• Wednesday at 12:55 a.m. EST: Shuttle lands at Kennedy Space Center.

Flight controllers study possible computer glitch

NASA mission managers are studying a potential problem with the General Purpose Computer system onboard shuttle Discovery but it is unclear what, if any, affect the possible glitch may have on planned operations tonight to return the Italian Leonardo supply module to Discovery's cargo bay.

The concern surfaced earlier today when flight controllers saw that the shuttle's coolant lines had become too cold because of the way Discovery was oriented in space while docked to the station. To prevent the lines from freezing, the crew was instructed to turn on some of the spaceship's electronics that had been powered down to conserve energy.

By powering up the electronics, the resulting heat from their operation warmed up Discovery and solved the coolant line concern.

Among the electronics turned on were two of the shuttle's main computers. There are four such computers operating during critical mission operations -- such as launch and landing -- but while in space the crew usually can rely on just two of the devices.

When powering up the computers, procedures call for a minimum wait of 10 seconds between activating each computer. Apparently the crew turned on computers No. 2 and No. 4 too quickly and software engineers on the ground are making sure that no software glitch was introduced into the system by turning on the computers too quickly.

NASA mission commentator Rob Navias reports that Mission Control has not detected any problems, but the analysis continues.

If the computers have to be recovered by re-loading their software from a protected source, the procedure will take about three hours and could delay the operation tonight to remove Leonardo from the station and place it back in Discovery's cargo bay.

The task involving Leonardo is scheduled to begin about 10 p.m. EST with the final hatch closing between Leonardo and the station.

Computers should be OK, planned work continues

After a day-long review of shuttle Discovery's four main computers and its software, NASA mission managers have decided they do not have a problem that would have required an unprecedented reloading of software in space to fix the problem.

What potentially could have been a serious problem cropped up earlier Saturday when two of Discovery's four main computers were powered up in an effort to warm shuttle coolant lines.

Flight controllers noted that the lines were becoming too cold and feared that ice might form within them.

The two computers had been turned off earlier in the mission to conserve electricity. Turning them back on enabled flight controllers to power up spaceship electronics, providing the heat needed to resolve the cooling line concern.

Routine start-up procedures, however, require a 10-second wait between the activation of each computer. The astronauts, however, apparently turned on the two computers within just six seconds, raising concerns that operating system software might have been compromised.

Analysis has since proved the software is fine, but a confidence test will be performed within the next hour or so by transitioning the computers from one computer program to another, and then verifying that everything is working as it is supposed to.

The computer concern has put the crew about an hour behind schedule for the main task of the evening, which is to remove the Italian Leonardo supply module and return it to Discovery's cargo bay. That effort is now expected to begin with the robot arm grabbing onto Leonardo about 1:30 a.m. EST Sunday.

Night is running long, but everything A-OK

The effort to return the Italian supply module Leonardo to the cargo bay of shuttle Discovery continues this morning. There are no problems to speak of, but the effort is a couple of hours behind schedule.

Concerns earlier today with the shuttle's computers is mostly to blame. But a test of the computer software verified everything was fine and the crew continued in their timeline.

Hatches between the Italian module and the space station were marked closed at 11:35 p.m. EST Saturday.

At this hour the crew is beginning to depressurize the small passageway between the Leonardo module and the Unity connecting node. The shuttle's 50-foot-long robot arm also is being powered up for the duty ahead.

Astronaut Andy Thomas will be the main man operating the robot arm to grapple Leonardo and then move it into position into Discovery's cargo bay. Just about everyone else in space right now will be helping in one fashion or another.

Leonardo should be locked in place inside Discovery within the next couple of hours.

Leonardo on the move

The Italian supply module Leonardo is on the move toward Discovery's cargo bay and should be securely latched for the return trip home to Earth within the hour.

The effort is several hours behind schedule thanks to earlier issues with the shuttle's computers and the seals between Leonardo and the station, both of which were cleared.

Hatches between Leonardo and the station were closed at 11:35 p.m. EST Saturday, and then Discovery's robot arm grappled the Italian module at 1:59 a.m. EST. The moving van was unberthed from the station at 5:42 a.m. EST and at this moment is waiting a few feet above the cargo bay while final alignments are in work.

Once Leonardo is safely tucked away, the crew will quickly wind down their day and head for bed to rest up for tonight's major events: a change in command ceremony, final hatch closure, undocking and a fly-around of the station.

Landing remains set for early Wednesday.

Leonardo locked in place within Discovery

The major mission goal for today was accomplished just after 7 a.m. EST when the Italian supply module Leonardo was securely fastened to Discovery's cargo bay.

The task came several hours behind schedule thanks to a couple of technical concerns that needed troubleshooting but didn't require any major work such that today's goal had to be put off a day or more.

Most of the visible effort tonight came courtesy of astronaut Andy Thomas, who operated the shuttle's 50-foot-long robot arm to grapple Leonardo, remove it from the space station and lower it into Discovery's cargo bay.

Attention now will turn toward getting a good night's sleep in anticipation of a busy and emotion-filled shift tonight, during which the shuttle crew will say good bye to the new station crew, close the hatches and then undock from the orbital outpost.

Our coverage of those activities will begin at 10:30 p.m. EST tonight.

Usachev takes command

In a dignified and emotion-filled change of command ceremony Sunday evening, astronaut Bill Shepherd passed the space station Alpha logbook to cosmonaut Yuri Usachev. Usachev now is officially in charge of the orbiting outpost.

The ceremony came about an hour earlier than planned so that live television could be beamed to Earth. A replay is scheduled on NASA TV at 8:37 p.m. EST and the footage no doubt will be part of the daily video highlights package that will be aired all day Monday.

Next goal for tonight will be to close the hatches between Alpha and Discovery, officially marking the beginning of the Expedition Two crew increment on the station. That event also is expected about 8:37 p.m. EST.

Then about three hours later Discovery pilot Jim Kelly will take the controls to undock the shuttle and fly it once around the station before changing orbits to move a safe distance apart.

Hatches closed between shuttle and station

The hatches between shuttle Discovery and station Alpha are closed as the process continues that will lead to undocking two hours from now.

More importantly, in closing the hatches the Expedition Two increment has officially begun aboard the space station. Hatch closing time was 9:32 p.m. EST.

The event came about two hours after a moving change in command ceremony in which Expedition One chief Bill Shepherd relinquished command to Expedition Two boss Yuri Usachev.

Next up for the mission: undocking at 11:32 p.m. EST.

Discovery pilot Jim Kelly will be at the controls as the shuttle backs away from the station and then loops the outpost once before separating a final time.

Here's the latest story from Cape Canaveral Bureau Chief Todd Halvorson.

New station crew gets its first scare

A false fire alarm aboard the International Space Station this morning sent the new Expedition Two crew scrambling to execute emergency procedures, but they had trouble doing even that due to an apparently unrelated problem with the station computers that kept them from reading those procedures.

Here's some more details from an Associated Press story:

"That's not a very good situation to be in, is it?" complained astronaut Jim Voss, the flight engineer.

The crew's so-called Red Book, an inch-thick volume on emergency procedures, includes information on dealing with a fire as well as false alarms, said NASA spokesman James Hartsfield.

Voss informed Mission Control that he and his crewmates had the Red Book out and were following its guidelines.

Russian commander Yuri Usachev and his crew immediately rummaged through the lab, to make sure nothing was smoldering.

"We looked at the smoke detector. ... There was no smoke, no smell," Usachev reported. "It is obvious that this is a false alarm." But he grumbled about the computer problems and noted: "The situation is not very good."

Usachev and Voss indicated they would like more documents sent up, to avoid any confusion in the future. Usachev's comments made it sound as though the crew had difficulty finding the on-board instructions to deal with the situation.

NASA believes that dust stirred up by the crew may have triggered the alarm or that the smoke detector may be defective. The three smoke detectors in the lab use laser beams to measure particles in the air, and are extremely sensitive. The smoke detector in question was later disconnected.

The air-circulating fans were turned off automatically when the alarm sounded, and came back on one by one. This safety feature, to smother any flames and prevent the spread of smoke, was not in place when a fire erupted aboard Russia's Mir station in 1997 and burned for 14 terrifying minutes.

Before going to sleep, astronaut Susan Helms told Mission Control she would have lots of questions the next day "about what was going on with the computers when all this happened."

The fleeting computer problem appeared to be unrelated to the false alarm, Hartsfield said.

Florida landing tonight doesn't look good

The landing drill for tonight looks like it will be about the same as it's been for the past few shuttle missions, with bad weather forecast again at the Kennedy Space Center to mix things up a bit.

In fact, unless the clouds, rain and wind now over the Space Coast clears away -- something it is not forecast to do -- there's little chance Discovery will touch down here early Wednesday morning.

Meanwhile, the weather is expected to be perfect at Edwards Air Force Base in California for tonight's landing attempts and a team of shuttle workers will be ready to greet Discovery if mission managers send the shuttle there.

As a result, what happens overnight tonight will depend on what the forecasts say for Florida and California early Thursday and how confident weather officials are in those forecasts.

Right now, KSC looks bad for Wednesday and is only marginally better on Thursday. Edwards is good Wednesday and a little worse on Thursday. That scenario might prompt mission managers to take a look at KSC and then choose to land at Edwards on Wednesday.

The first opportunity to get a sense of what might actually happen will come about four hours before the initial chance to land at KSC at 12:56 a.m. EST Wednesday, or about 9 p.m. EST tonight. That's when a decision is expected on closing Discovery's cargo bay doors.

And that's when this page will be updated again.

Landing delayed, Florida unlikely

NASA is looking hard at the possibility of bringing Discovery and its crew home to Edwards Air Force Base in California just before dawn on Wednesday morning.

Weather over Florida is as bad as predicted and the shuttle crew have already been told they will not land at Kennedy Space Center on the first opportunity at 12:56 a.m. EST Wednesday.

The second Florida opportunity is officially still a possibility and the crew will step through their deorbit procedures as though they were going to land at 2:31 a.m. EST Wednesday, but it would only be through divine intervention that the weather would clear enough in time to allow that to happen.

Since the weather over Edwards is expected to be perfect tonight, and the forecasts for both landing sites on Thursday include some uncertainty about acceptable conditions, it is likely that NASA mission managers would decide to bring Discovery home to California on Wednesday.

In that case Discovery's braking rockets would be fired at 2:57 a.m. EST and the landing would come at 4:02 a.m. EST.

The next decision point likely will come around 11 p.m. EST tonight when Discovery's payload bay doors would need to be closed for the second Florida landing attempt.

Do you believe in miracles?

If you don't believe in miracles then let us offer into evidence this fact: the weather over Kennedy Space Center, despite all predictions to the contrary, is clearing enough that there is "growing optimism" within Mission Control in Houston that Discovery might make it back to the Florida spaceport tonight.

Although far from a done deal, the skies do appear to be clearing, the rain is staying away and the winds are not blowing as hard as they were forecast. And so far, chief astronaut Charlie Precourt is not finding a lot to talk about as he flies a weather monitoring aircraft over Central Florida.

The official weather forecast remains "no go," and observed conditions are right on the margin now, but things do seem to be improving.

A final decision is still hours away, but if approved would result in the shuttle firing its braking rockets at 1:26 a.m. EST and landing on runway 15 at KSC at 2:31 a.m. EST Wednesday.

To be ready for a KSC landing, Mission Control has ordered Discovery's crew to close the shuttle's payload bay doors, one of the first major steps in completing the final landing preparations. That will quickly be followed by the crew loading their landing software into the computers.

If the weather picture remains uncertain, NASA mission managers continue to hold the option of landing Discovery at Edwards Air Force Base in California at 4:02 a.m. EST. Weather there is ideal.

Discovery gets 'go' for landing

A few hours ago you could have bet the house that Discovery wouldn't land at the Kennedy Space Center this morning.

You would have lost.

The astronauts have just been told they have official blessings to fire Discovery's braking rockets at 1:26 a.m. EST and bring the 100-ton spaceplane out of orbit, aiming to land at KSC's shuttle runway 15 at 2:31 a.m. EST.

The de-orbit burn will last two minutes and 54 seconds, slowing the shuttle down by 303 feet-per-second -- just enough to cause Discovery to fall out of orbit and begin the hour-long supersonic glide home.

Discovery non-stop and direct to Florida

Shuttle Discovery and its crew of seven men are on their way to the Kennedy Space Center in Florida, committed to a single chance to land at 2:31 a.m. EST this morning.

Discovery commander Jim Weatherbee and pilot Jim Kelly fired the shuttle's twin orbital maneuvering engines in a braking action that slowed the 100-ton spaceplane by some 303 feet per second, just enough to begin the supersonic dive through Earth's atmosphere.

With this event behind them there is no turning back for Discovery and no second chance to reconsider if the weather should suddenly turn bad. Commander Wetherbee must land the shuttle on the three-mile-runway here.

Speaking of the weather, the poor conditions forecast for Central Florida cleared the area and allowed mission managers to approve the landing. If a KSC touchdown were not possible, the space agency was ready to send Discovery and its crew to Edwards Air Force Base in California.

The shuttle will officially enter Earth's atmosphere in about a half-hour, after which the shuttle's speed will begin to slow at a more rapid rate and the astronauts will be able to enjoy a light show out their windows.

The shuttle is to touch down on runway 15. Discovery will approach the area from the south with its nose pointing to the northeast and then make a wide left-hand turn to align itself with the runway. The trademark sonic booms will be heard a couple of minutes before landing.

We will update this page again following the landing.