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For 1:45 p.m. EST Sunday, Feb. 4

Atlantis astronauts arrive in Florida for launch

Overcast skies and a chilly breeze greeted the five Atlantis astronauts this afternoon as the crew of STS-98 arrived at the Kennedy Space Center for their planned launch Wednesday to the International Space Station.

The four men and one woman flew to Florida in their T-38 training jets, touching down at KSC's Shuttle Landing Facility runway at 1:43 p.m. EST.

NASA begins countdown to Atlantis launch

Countdown clocks are ticking again at the Kennedy Space Center as the shuttle launch team has begun final preparations to send Atlantis and the U.S. science lab Destiny on its way to the International Space Station on Wednesday.

The standard 43-hour countdown -- which began at 10 p.m. Sunday and includes several built-in holds -- should lead to Atlantis launching from pad 39A at 6:11 p.m. EST Wednesday. The exact liftoff time may change by a minute or so depending on the station's orbit on launch day.

The early weather outlook is favorable, with an 80 percent chance of acceptable conditions.

There was a new concern raised during the weekend about the two spacewalking spacesuits installed on Atlantis, prompting officials to decide to swap out the suits with spares flown in from Houston. The unplanned work is not expected to delay the launch, officials said.

Countdown continues without trouble

NASA launch officials report all is well this morning with the countdown that began at 10 p.m. EST Sunday.

There was some more discussion at the morning briefing about the two spacewalking spacesuits that had to be replaced because of concerns over a weld inside a suit systsem that had not been inspected. One spacesuit already has been replaced inside Atlantis and the second is due today.

The weather forecast still looks good with an 80 percent chance of acceptable conditions. Coastal rainshowers seems to be the only concern.

The major countdown event for today will be loading Atlantis' electricity-generating fuel cell system with its supply of liquid hydrogen and liquid oxygen reactants.

NASA managers clear Atlantis to fly

The space agency has just concluded its traditional pre-launch press conference with shuttle program manager Ron Dittemore reporting that Atlantis is in good shape and is ready to fly the Destiny science lab to the International Space Station (ISS).

Launch remains set for 6:11:15 p.m. EST Wednesday, although that time may be slightly adjusted depending on the exact orbit the station is in on launch day.

Air Force weather office Capt. Clif Stargardt reported the forecast remains favorable, with an 80 percent chance of acceptable conditions.

Among the comments that surfaced during today's briefing:

• Atlantis will be flying with a new version of its operating software, giving astronauts and flight controllers more flexibility in handling possible emergency landings along the U.S. east coast.
• NASA will not say what its policy is on visiting astronauts to the ISS because it hasn't come up with one yet. That will be ironed out by the station partners in the coming weeks, apparently in time to deal with the imminent flight of U.S. businessman Dennis Tito on a Russian rocket.
• Officials have not yet decided what mission Columbia will fly next when it returns to Florida later this month after spending several months in California for an overhaul. The possibility that Columbia eventually might be used by military or commercial endeavors was not dismissed by Dittemore.

Countdown remains problem free

NASA managers report this morning there are no significant problems out at launch pad 39A with the countdown to send Atlantis and five astronauts on their way to the International Space Station Wednesday.

Weather forecasts look great for the Cape Canaveral area, with a 90 percent chance of acceptable conditions during the 10-minute launch window. However, the weather over three emergency landing sites across the Atlantic Ocean is forecast to be "iffy."

NASA only needs one of the three sites to be available in order to allow Atlantis to lift off, but clouds and winds are expected to be a concern at all three airports.

Atlantis is being fueled for launch

The process of filling shuttle Atlantis' external tank with its half-million gallons of liquid hydrogen and liquid oxygen began at 8:46 a.m. EST today out at launch pad 39A.

That means everything is on schedule and looking good for the launch later today at 6:11 a.m. EST.

Weather forecasts at the Cape are now 100 percent go, and although all three trans-Atlantic abort sites currently are no-go, NASA spokesman Joel Wells said forecasters believe Ben Guerur in Morocco will become acceptable later this afternoon.

Here is the timeline from the latest KSC shuttle status report detailing events planned for today:

• 6:30 a.m. Crew wake up
• 7 a.m. Breakfast
• 7:30 a.m. Medical Checks
• 12:30 p.m. Lunch
• 1:10 p.m. Photo opportunity
• 1:41 p.m. Weather Briefing (CDR, PLT, MS2)
• 1:41 p.m. Don flight suits (MS1, MS3)
• 1:51 p.m. Don flight suits (CDR, PLT, MS2)
• 2:21 p.m. Depart for launch pad
• 2:51 p.m. Arrive at white room and begin ingress
• 4:06 p.m. Close crew hatch
• 6:11 p.m. Launch

Atlantis fueled, astronauts getting ready

Atlantis' external tank is full and there continues to be no major technical problems reported.

The five-member crew was just seen on NASA TV posing in front of their traditional mission cake and now are attending weather briefings and getting ready to don their orange launch and entry suits.

Weather at the launch site continues to look perfect, but the three overseas emergency landing sites still don't look good.

At least one of the sites must have acceptable weather and mission managers remain hopeful because the weather over Ben Guerur in Morocco appears it may clear in time.

Here is the timeline from the latest KSC shuttle status report detailing events planned for the rest of today:

• 1:41 p.m. Weather Briefing (CDR, PLT, MS2)
• 1:41 p.m. Don flight suits (MS1, MS3)
• 1:51 p.m. Don flight suits (CDR, PLT, MS2)
• 2:21 p.m. Depart for launch pad
• 2:51 p.m. Arrive at white room and begin ingress
• 4:06 p.m. Close crew hatch
• 6:11 p.m. Launch

Atlantis hatch sealed for launch

All five astronauts are strapped into their seats inside Atlantis' crew cabin and the shuttle's main hatch was closed and latched for flight at 4:13 p.m. EST.

So far everything continues to go well with the countdown. A couple of minor problems with ground support equipment at the launch pad was easily fixed and the launch team is not working any issues, according to reports from NASA launch commentator George Diller.

The weather around Kennedy Space Center has turned even nicer than it was earlier today, with clear skies over the Cape, gentle breezes and comfortable temperatures.

Weather continues to be a concern at the three emergency landing sites, but optimism remains that conditions over the runway at Ben Guerer in Morocco will be acceptable by launch time.

Atlantis hatch sealed for launch

The exact launch time for tonight's shuttle launch is to be 6:11:16 p.m. EST.

Technically there are no issues being addressed with shuttle Atlantis and the weather remains ideal.

New weather data from overseas continues to indicate that Ben Guerer in Morocco will be acceptable by the time the launch window opens, so there is growing optimism that tonight will be the night Atlantis takes the Destiny science lab into orbit.

Once airborne Atlantis will take eight minutes and 31 seconds to reach orbit with the help of its twin solid rocket boosters, three Rocketdyne main engines and an extra boost from the orbital maneuvering system engines firing for a little more than a minute.

Atlantis countdown nears conclusion, all systems go

All still looks good for launch of shuttle Atlantis at 6:11:16 p.m. EST.

Members of the launch team are discussing a problem with a piece of electronics but the trouble reportedly does not violate any launch rules, so although troubleshooting continues it doesn't appear the launch will be delayed -- yet.

Weather continues to look good here at the Cape and has been deemed acceptable for launch overseas at Ben Guerer in Morocco.

Once airborne Atlantis will take eight minutes and 31 seconds to reach orbit with the help of its twin solid rocket boosters, three Rocketdyne main engines and an extra boost from the orbital maneuvering system engines firing for a little more than a minute.

Atlantis safely arrives in orbit

NASA Mission Control in Houston confirms that Atlantis' main engines have shut down and the five astronauts and Destiny science lab are safely in orbit over Earth.

Atlantis in orbit, payload bay doors open

NASA's Mission Control has officially given the five-member crew of shuttle Atlantis a "go" for orbital operations, signaling the fact the spaceship has safely arrived in a proper orbit and opened its cargo bay doors.

The 60-foot-long doors were opened at 8:02 p.m. EST -- a fairly routine event that must happen in order to allow the orbiter to cool its electronics because the heat-radiators line the inside of the doors.

Atlantis now continues a two-day long chase of the International Space Station that began with the launch. Rendezvous and docking is expected just before noon EST on Friday.

Expect our next update to this page about 10 a.m. Thursday.

Progress undocks with station

A Progress cargo freighter undocked with the International Space Station earlier this morning, clearing the way for shuttle Atlantis to join with the outpost midday Friday.

The unmanned spacecraft pulled away from space station Alpha at 6:26 a.m. EST today, taking with it unneeded equipment and garbage. Later in the day the Progress ship was sent diving into Earth's atmosphere, where it burned up.

Onboard Atlantis the crew tested the spacesuits that will be worn during three planned spacewalks, checked out the shuttle's robot arm and continued maneuvering the orbiter on its two-day chase of the space station.

Docking is now expected at 11:50 a.m. EST on Friday.

For a full docking preview, read this latest story.

We will update this page again at 10 a.m. EST Friday.

Atlantis on final approach to Alpha

Shuttle astronauts fired Atlantis' maneuvering engines at 9:24 a.m. EST to begin the final approach of the spaceplane to the orbiting outpost.

Several small course corrections are possible during the next couple of hours but Atlantis is on its last leg of a two-day journey that began with the 6:13 p.m. EST launch Wednesday from the Kennedy Space Center.

Docking still is expected at 11:50 a.m. EST today. That event will be followed at 1:43 p.m. this afternoon with the hatch opening between Atlantis and the station and a brief welcoming ceremony.

The crew will then begin to transfer a supply of food, clothing, equipment and a few surprises from the shuttle to the station before closing the hatches at 6:03 p.m. EST in anticipation of Saturday's spacewalk.

For a full docking preview, read this latest story.

Atlantis closing on station for on time docking

Atlantis now less than 300 feet from the International Space Station and closing right on schedule.

Everything looks good for docking at 11:50 a.m. EST today.

The final approach began at 9:24 a.m. EST with the so-called Terminal Initiation burn, which was followed by four small course corrections that put Atlantis on the precise path it was supposed to be on.

Commander Ken Cockrell is now manually flying Atlantis to dock with the station.

Docking will be followed at 1:43 p.m. EST this afternoon with the hatch opening between Atlantis and the station and a brief welcoming ceremony.

The crew will then begin to transfer a supply of food, clothing, equipment and a few surprises from the shuttle to the station before closing the hatches at 6:03 p.m. EST in anticipation of Saturday's spacewalk.

For a full docking preview, read this latest story.

Shuttle Atlantis returns to Space Station Alpha

Once again the Space Shuttle Atlantis is docked to the International Space Station.

Looking up through overhead windows, shuttle skipper Ken Cockrell skillfully flew Atlantis exactly into position to join with the orbiting outpost at 11:51 a.m. EST while both vehicles were moving more than five miles per second.

Latches will now be driven shut, the gap between the two vehicles pressurized and the seals tested for leaks.

If all continues to go well, the hatches between the two ships will be opened at 1:43 p.m. EST and the three-man station crew led by astronaut Bill Shepherd will host a brief welcome ceremony.

The crew will then begin to transfer a supply of food, clothing, equipment and a few surprises from the shuttle to the station before closing the hatches at 6:03 p.m. EST in anticipation of Saturday's spacewalk.

Shuttle Atlantis returns to Space Station Alpha

Hatches between shuttle Atlantis and the International Space Station were opened at 2:03 p.m. EST today, about two hours after the two ships were joined together with Atlantis skipper Ken Cockrell at the controls.

Unfortunately the event happened just as the orbiting complex was moving out of range of being able to broadcast television images of the reunion between the two crews. A playback of the event is expected later in the afternoon.

The hatches will stay open for about four hours, allowing the initial transfer of a supply of food, clothing, equipment and a few surprises that include chocolate and DVD movies.

At 6:03 p.m. the hatches are to be sealed tight again so that Atlantis can reduce its cabin pressure to support the first of three spacewalks planned for this mission. That spacewalk is scheduled to begin Saturday morning a little after 10 a.m. EST.

First spacewalk has begun

Astronauts Tom Jones and Robert Curbeam have officially begun their spacewalk today to assist in the installation of the Destiny science module to the International Space Station.

The spacewalk start time came at 10:50 a.m. EST when the spacewalkers switched to internal power, using the suit batteries. At that point they each had about eight hours worth of power and oxygen to finish the planned tasks.

"Enjoy the walk and good luck," CAPCOM Mario Runco told the two men.

The effort is running a little behind schedule but there is nothing going wrong. The plan for today remains the same.

The spacewalkers will first help guide the docking port freed earlier this morning to a temporary parking spot. Their spotting work will continue as Marsha Ivins uses the robot arm to lift Destiny and move it into place, when it will be latched into place. The spacewalkers will then connect power and coolant lines between Destiny and the rest of the station.

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

Live coverage of the spacewalk is available from SPACE.com on our STS-98 Mission Console.

Note: Jones is considered EV1 and has red stripes on his suit. Curbeam's suit does not.

And for a reminder of what is in store for the spacewalk and Destiny installation, see this SPACE TV report.

We'll contuinue to update this page with the spacewalk's progress throughout the day.

Destiny lab unberthed from cargo bay

With the spacewalk now more than two hours old, everything is moving along without trouble and the effort is more or less proceeding as scheduled.

The Pressurized Mating Adapter (PMA) was removed from Unity at 10 a.m. EST, parked against the Z-1 truss at 11:47 a.m. EST and firmly latched to the truss with the help of spacewalker Tom Jones at 11:54 a.m. EST.

Attention then turned to the Destiny lab, which is now headed for the spot against Unity that the PMA had just occupied.

Robot arm operator Marsha Ivins grabbed Destiny at 12:23 p.m. EST, saying "Houston, we have a lab." Then after spacewalker Robert Curbeam moved down toward the shuttle's tail to make sure Ivins had enough clearance, the lab was raised from the cargo bay and cleared its retention latches at 12:48.

Ivins is now performing a 180-degree flip that will put the lab into its proper orientation to be mated against the Unity module within the next hour.

Once that is done, Jones and Curbeam will hook up some power and coolant lines that will allow the crew to remotely activate the lab later today.

The astronauts won't actually enter Destiny until Sunday morning.

Here's the latest story from Cape Canaveral Bureau Chief Todd Halvorson posted at 11:15 a.m. EST.

Live coverage of the spacewalk is available from SPACE.com on our STS-98 Mission Console.

Note: Jones is considered EV1 and has red stripes on his suit. Curbeam's suit does not.

And for a reminder of what is in store for the spacewalk and Destiny installation, see this SPACE TV report.

We'll next update this page following Destiny's attachment to the station.

Destiny attached to Station Alpha!

The International Space Station has a new $1.4 billion science laboratory attached to it, an historic milestone for the space station program.

Robot arm operator Marsha Ivins slowly moved the 16-ton lab into position against the Unity module and the first four capture latches grabbed hold at 1:58 p.m. EST today.

With that done, Jones and Curbeam are now hooking up power and coolant lines that will allow the crew to remotely activate the lab later today.

Curbeam is having some trouble connecting an ammonia coolant line, and one of the quick-disconnects began leaking the fluid, which turned into a shower of crystals that sprayed into space. The spacewalkers are discussing the situation with Mission Control and are making sure none of the ammonia is stuck to their suits.

Here's the latest story from Cape Canaveral Bureau Chief Todd Halvorson posted at 11:15 a.m. EST.

Live coverage of the spacewalk is available from SPACE.com on our STS-98 Mission Console.

Note: Jones is considered EV1 and has red stripes on his suit. Curbeam's suit does not.

And for a reminder of what is in store for the spacewalk and Destiny installation, see this SPACE TV report.

First spacewalk nears completion

Spacewalkers Tom Jones and Robert Curbeam are wrapping up their first work sortie outside the space station complex, but cleaning up and getting back inside shuttle Atlantis is going to involve a few extra steps.

The reason: after Destiny was attached to the station, Curbeam began installing coolant lines, but one of the quick disconnects began leaking ammonia, spraying Curbeam with a shower of toxic crystals.

Although the spacewalkers were completely safe from the release, Mission Control has directed the crew to work through some extra procedures to make sure neither Curbeam nor Jones returns inside the airlock with any ammonia crystals. The concern being that the crystals could then turn into ammonia gas.

The extra precautions being taken before the pair go back inside include brushing down their suits and baking in the sunlight. Then when they get inside the airlock will be repressurized, then depresurized, then repressurized again before the airlock hatch is opened and the two spacewalkers are allowed into Atlantis' middeck.

The ammonia leak was quickly fixed and it marked really the only trouble for the oribital construction workers today.

Moving a docking port and installing the giant, 16-ton Destiny science module was accomplished in fine fashion, once again with the crew making it look easy.

Here's the latest story from Cape Canaveral Bureau Chief Todd Halvorson posted at 11:15 a.m. EST.

Live coverage of the spacewalk is available from SPACE.com on our STS-98 Mission Console. Note: Jones is considered EV1 and has red stripes on his suit. Curbeam's suit does not.

We will update this page again after the spacewalkers are safely back inside and the airlock hatch is open.

Spacewalkers safe, Destiny activation next

Spacewalking astronauts Tom Jones and Robert Curbeam have returned to the safety of shuttle Atlantis' crew cabin tired, but with no apparent ill effects from being exposed to a shower of toxic ammonia crystals during their extravehicular activity today.

After helping to attach the Destiny lab to the station, Curbeam was installing a coolant line when the quick-disconnect he was to attach a hose to began spewing liquid ammonia, which instantly froze in the vacuum of space.

Protected by their spacesuits from the otherwise potentially deadly substance, the pair had to perform some decontamination procedures in the airlock before they were allowed back inside, lengthening an already busy work day.

During the next few hours the shuttle and space station crews will begin activating the Destiny module, however the crews won't enter the lab until tomorrow morning.

For those who are keeping track: Today's EVA lasted seven hours and 34 minutes. It was the 98th in history by U.S. astronauts for a total of 365 hours and four minutes spent outside a spaceship, and the 14th EVA hosted outside the space station for a total of 96 hours and 28 minutes spent working on the outpost.

Here's the latest story from Cape Canaveral Bureau Chief Todd Halvorson posted at 8:30 p.m. EST.

Critical first steps for Destiny complete

Crew members aboard shuttle Atlantis and space station Alpha are heading for bed at this hour, concluding a very long day that saw the successful installation and initial activation of the Destiny science lab to the International Space Station.

During the past hour or so some of Destiny's most critical power and cooling systems were turned on to ready the laboratory for its first occupants on Sunday.

With permission from Mission Control to sleep in an extra hour in the morning, the six astronauts and two cosmonauts currently in orbit will open the hatch to Destiny and enter for the first time at 9:13 a.m. EST Sunday.

They'll spend another jam-packed day moving equipment and supplies into Destiny and the rest of the station before closing up the hatches between Atlantis and Alpha to support the missions' second spacewalk, which is scheduled for Monday.

Meanwhile, here's the latest story from Cape Canaveral Bureau Chief Todd Halvorson, which we posted at 8:30 p.m. EST Saturday.

See you in the morning.

Astronauts board Destiny

Here's the latest story.

The world's biggest space station in history was officially opened for business this morning as members of the shuttle Atlantis and space station Alpha crews boarded the newly added Destiny laboratory for the first time.

Atlantis commander Ken Cockrell and Alpha commander Bill Shepherd were the first inside at 9:38 a.m. EST after Shepherd signed a document acknowledging receipt of the government property.

Cockrell almost immediately reported that there was no small debris floating around the lab and that Destiny "looks and feels and smells great."

The 16-ton module was attached to the space station on Saturday, increasing the available pressurized volume at the outpost by 41 percent and making Alpha more roomy than the Russian space station Mir or the U.S. Skylab of the 1970s.

The six astronauts and two cosmonauts now in space will spend about eight hours inside Destiny today, continuing to activate its systems and fill the lab with equipment and supplies.

Then the shuttle crew will retreat to Atlantis and close the hatches to the space station to set the stage for a second spacewalk planned for Monday.

Spacewalking duo back outside

Here's the latest story, posted at 11:45 a.m. EST.

Astronauts Tom Jones and Robert Curbeam are outside Atlantis' airlock and have moved into position to release the Pressurized Mating Adapter No. 2 that is at the parked position on the Z-1 truss.

The spacewalk officially began at 10:59 a.m. EST, a little later than planned but not a problem.

Before the EVA began, mission specialist Marsha Ivins moved the robot arm to grapple the PMA docking adapter. The PMA was originally attached to the Unity module, but was removed on Saturday to make room for Destiny.

Today's operation is critical for future shuttle missions to the station because in order for the assembly sequence to work as planned, space shuttles must be able to dock to PMA 2 in its new location.

If that didn't make sense, or you can't quite picture it in your head, watch this NASA animation showing what will happen to the PMA.

Meanwhile, at the Kennedy Space Center shuttle Discovery is on its way to launch pad 39B. Discovery is to blast off on an outfitting mission to the space station in March and will have to use the PMA docking port the Atlantis crew is dealing with today.

Second spacewalk declared a success

Here's the latest story, posted at 7:30 p.m. EST.

The second of three planned spacewalks is finished, with both Robert Curbeam and Tom Jones safely inside Atlantis, the hatch closed and the airlock repressurizing.

Official duration of today's spacewalk was six hours and 50 minutes. It began at 10:59 a.m. EST and ended at 5:49 p.m. EST.

All went well during the extravehicluar activity, the 99th in U.S. space program history.

The Pressurized Mating Adapter 2 was repositioned from a temporary park position to the open end of the Destiny science laboratory by robot arm operator Marsha Ivins, while the two spacewalkers kept an eye on the hardware movement.

After making sure the docking adapter was securely fastened to Destiny, the spacewalkers removed a cover on a specially-made station window and installed some hardware that will be used by future station crews.

Along the way the crew welcomed the news of NEAR's apparent soft landing on the asteroid Eros.

The next spacewalk is scheduled for Wednesday.

Tomorrow the shuttle crew will enjoy a half-day off and then spend a quiet rest of the day, with the only significant activity being to raise the station's orbit by firing the shuttle's thrusters.

Destiny activation continues to go well

The latest NASA shuttle mission status report very clearly lays out what has happened so far today and what is planned for the next few hours. In other words, I couldn't have said it better myself:

Atlantis' astronauts were awakened shortly after 4 a.m. Central time today to AC/DC's "For Those About to Rock," announcing the start of Flight Day 7 on board the Shuttle. About two hours later, International Space Station (ISS) flight controllers

began a series of critical tests to ensure the newly activated computers in the Destiny Laboratory module of the ISS could take over control of the orientation of the Station from Russian segment computers. It was the first time that U.S. computers in Destiny provided control of the ISS, an important first in Station operations to preserve propellant previously used in orienting the ISS to the sun for the generation of electricity.

The Expedition One crewmembers - Commander Bill Shepherd, Pilot Yuri Gidzenko and Flight Engineer Sergei Krikalev - were awakened a short time before the tests began, having been granted two additional hours of sleep after working late Monday night to continue the activation and checkout of Destiny's systems.

The so-called "control authority" tests will continue throughout the week, as control of the Station is handed back and forth between the Zvezda module and Destiny, verifying that the new laboratory can provide command and control capability for Station orientation through the operation of four large gyroscopic devices housed on the Station's Z1 truss. The gyros were operating perfectly early today, displaying good speeds and normal temperatures as they worked to gently steer the Station to provide correct alignment of the U.S. and Russian module solar arrays to the sun.

Shepherd provided an ISS status report for flight controllers, indicating that although there is a missing washer in Destiny, it will not harm the Lab's systems thanks to a series of filters associated with the air purification system in the new module. Shepherd also reported that he has detected some loose wires on the treadmill exercise device in the Zvezda module, but said the device remains operational. The treadmill is designed to eliminate vibrations caused by exercise which could disturb sensitive microgravity experiments.

Overnight, space station flight controllers issued final commands to tighten the bolts that secure a newly positioned docking port to the Destiny laboratory. The docking port was attached to Destiny during Monday's spacewalk. Flight controllers also continued commands to complete the activation of the Atmosphere Revitalization Rack in Destiny.

Commander Ken Cockrell and Pilot Mark Polansky will perform another reboost of the Station today, using Atlantis' jet thrusters to slowly raise the altitude of the ISS for future operations. Cockrell and Polansky will then join Mission Specialists Marsha Ivins, Bob Curbeam and Tom Jones for a few hours of off-duty time to relax and enjoy the view of Earth from orbit.

This afternoon, spacewalkers Curbeam and Jones will set out the tools they will use Wednesday during the third and final scheduled spacewalk of the mission, the 100th spacewalk in U.S. spaceflight history. During the planned five-hour excursion, Jones and Curbeam will attach a spare S-band communications antenna assembly to the Z1 truss, photograph the base of the huge U.S. solar arrays installed during the STS-97 mission in December, and practice techniques which could be used in the future to assist an incapacitated spacewalker.

Hatches remain closed between Atlantis and the ISS. They will be reopened following tomorrow's spacewalk for one more day of joint operations inside Destiny on Thursday.

Atlantis and the ISS are orbiting the Earth at an altitude of 230 statute miles with all systems operating in excellent shape.

Our next update will come with the posting of Cape Canaveral Bureau Chief Todd Halvorson's story later this afternoon.

Tuesday is a relatively quiet day in space

What can go wrong when you work for only half-a-day?

After a jam-packed few days that saw two spacewalks and the installation and activation of the Destiny science module, the crew of space shuttle Atlantis enjoyed some time off today before going on duty for some light chores.

In addition to being interviewed by news media, the chores included some early preparation for Wednesday's final spacewalk and gently raising the space station's orbit by using the shuttle's steering thrusters.

For a complete wrap up of today's events in space, plus a look ahead to what will be NASA's 100th spacewalk, read Cape Canaveral Bureau Chief Todd Halvorson's latest story posted at 5:45 p.m. EST Tuesday.

NASA's 100th spacewalk has begun

Here's this morning's newest story.

Astronauts Tom Jones and Robert Curbeam officially began the extravehicular activity, or EVA, at 9:48 a.m. EST and are expected to spend about five hours outside Atlantis and the International Space Station.

NASA's first EVA was during the Gemini 4 mission in 1965 when astronaut Ed White floated outside the two-man capsule.

During today's spacewalk, Jones and Curbeam will climb to the top of the Z1 truss and do some inspections, they will move an antenna, do some other clean up work and then practice emergency rescue procedures.

This is the third and final spacewalk planned for the STS-98 mission.

Final day docked together

Read this latest story posted at 5 p.m. EST

The six astronauts and two cosmonauts now aboard the joined Atlantis/International Space Station complex in orbit are working on their last full day docked together, moving equipment and supplies into the station from the shuttle.

Among the more interesting items being stowed on space station Alpha today is the spacesuit worn by Tom Jones during three spacewalks this week. That suit will be available for future station EVAs.

Another task being wrapped up today is an effort to raise the space station's orbit by using Atlantis' thrusters to gently add speed to the complex, which has the effect of increasing the altitude. (And as those of you who understand orbital mechanics knows, also has the effect of slowing down the station.)

The goal is for Atlantis to undock tomorrow with the station some 16 miles higher than it was when the shuttle docked last Friday.

This afternoon the combined crews will meet the press in the traditional in-flight news conference. That event is scheduled for 1:37 p.m. EST and can be seen on SPACE.com's live feed of NASA TV.

Undocking is scheduled for just after 9 a.m. EST on Friday, leading to a landing of Atlantis at the Kennedy Space Center at 12:52 p.m. EST Sunday afternoon.

Shuttle and station crews say farewell

Hatches between shuttle Atlantis and the International Space Station are closed and locked as preparations continue for the undocking later this morning at 9:06 a.m. EST.

The five Atlantis crewmembers said their final farewells to the three station Alpha crewmembers just before 8 a.m. and the airlock hatch leading up to the station was closed a short time later.

Atlantis docked to the station one week ago and since then the five astronauts successfully connected the $1.4 billion Destiny science lab and repositioned a docking adapter, growing the length of the orbiting outpost to 171 feet and making the station the largest in space history.

Following the undocking today pilot Mark Polansky will take the controls of Atlantis and fly the shuttle in a half-loop around the station to take photos and admire their handiwork.

Later today some of the Atlantis astronauts will be interviewed by several news media organizations, including SPACE.com. You can watch beginning about 2:45 p.m. EST right here.

Shuttle Atlantis separates from station Alpha

With a gentle push from a set of springs in the docking collar, Atlantis is backing away from the International Space Station right now after a week-long visit which saw the installation of a new $1.4 billion science laboratory that also will serve as the nerve cener for the ever-growing orbiting outpost.

During the next 40 minutes or so Atlantis pilot Mark Polansky will fly the shuttle a safe distance away from the station and then make a half-loop around the outpost. This will give the crew a chance to take photos of the station in its new configuration with the Destiny module.

At 9:47 a.m. EST Polansky will fire Atlantis' maneuvering engines to take the shuttle on a path that will put a considerable distance between the two ships and set up the spaceplane for its planned return to the Kennedy Space Center at 12:52 p.m. EST Sunday.

Later today some of the Atlantis astronauts will be interviewed by several news media organizations, including SPACE.com. You can watch beginning about 2:45 p.m. EST right here.

Atlantis moves away from Alpha after photo op

After easily undocking at 9:06 a.m. EST, Atlantis was flown in a half-loop around the International Space Station by pilot Mark Polansky before a separation maneuver was performed to safely distance the shuttle from Alpha.

During the abbreviated fly-around -- cut short by a lack of propellant -- spectacular new views of the station with its recently added Destiny science lab were beamed to Earth and broadcast on NASA TV.

Helping add a new perspective to the images was the fact that the station was slightly turned so that the same end-over-end views recorded by Endeavour's crew in December were not repeated again today.

One of the best views, in my humble opinion, is featured on this page. For a sampling of others, read Cape Canaveral Bureau Chief Todd Halvorson's latest story, which we posted at 11 a.m. EST.

And later today some of the Atlantis astronauts will be interviewed by several news media organizations, including SPACE.com. You can watch beginning about 2:45 p.m. EST right here.

Early landing forecast looks OK for KSC

It's all down hill from here.

With Atlantis undocked from the International Space Station and flying several miles apart -- a distance that is growing each minute -- attention has turned to the final leg of the mission that will see the shuttle take a supersonic dive through Earth's atmosphere aiming for a landing at the Kennedy Space Center.

Touchdown is now scheduled for 12:52 p.m. EST Sunday.

Before that can happen the shuttle astronauts must finish packing and complete a routine check of all systems that are used during the re-entry and landing procedure. That includes cranking up an auxiliary power unit to test the hydraulic systems and firing each of the spaceplane's 44 steering jets.

That check out effort is planned for early in their work day on Saturday.

Weather forecasts released Friday indicate a generally favorable situation for a return to Florida early Sunday afternoon. A cold front is expected to move through the Central Florida area this weekend bringing a chance of showers and gusting winds behind it.

But for now the forecast looks like a go for landing at KSC.

We will next update this page with all the landing plans and details after a briefing NASA has planned for late Saturday afternoon.

In the meantime, enjoy your weekend.

Payload bay doors closed for landing

Atlantis' 60-foot-long payload bay doors were closed and latched at 9:08 a.m. EST this morning, indicating that everything looks good right now for the space shuttle to land at Kennedy Space Center at 12:53 p.m. EST.

With the doors closed, Atlantis' electronics are being cooled by a flash evaporator system that uses water to remove the heat build up. Radiators that line the payload bay doors do the job during the majority of the mission but can't be used once the doors are shut.

Atlantis astronauts will now begin donning their orange launch and entry spacesuits and strap themselves into their seats for the remainder of the flight.

If the weather continues to be acceptable here at the Cape, Atlantis' twin orbital maneuvering engines will be fired at 11:47 a.m. EST. That will slow the spaceplane enough to drop it out of orbit and begin an hour-long supsersonic dive through Earth's atmosphere.

Again, touchdown is now set for 12:53 p.m. EST.

Weather looks good for now. There is still some concern about crosswinds, but the forecast is go at this hour.

Later this morning astronaut Charlie Precourt will take to the sky in a T-38 training jet initially, and then later in the Shuttle Training Aircraft -- a modified Grumman G-2 business jet -- to check on clouds, visibility, winds and turbulence over the area.

For a full landing preview, read Cape Canaveral Bureau Chief Todd Halvorson's latest story posted at 2 p.m. EST.

Atlantis will circle Earth one more time

Crosswinds at the shuttle runway here at the Kennedy Space Center are blowing too hard to allow Atlantis to return home for a landing at 12:53 p.m. EST.

As a result the crew have been told to stay in orbit and circle the Earth one more time, hoping to land at 2:28 p.m. EST. The deorbit burn would come at 1:22 p.m. EST and a landing decision would be expected a few minutes before that.

Winds still will be an issue.

If Atlantis cannot land in Florida today, NASA will keep the shuttle and its five astronauts in space one more day and make another landing attempt on Monday.

Both the Florida site and the field at Edwards Air Force Base in California would be considered.

Atlantis has enough supplies to stay in space until at least Wednesday.

For a full landing preview, read Cape Canaveral Bureau Chief Todd Halvorson's latest story posted at 2 p.m. EST Saturday.

No landing for Atlantis crew today

High crosswinds continued to blow too hard today at the Kennedy Space Center shuttle runway, prompting Mission Control to tell the crew of shuttle Atlantis they will be spending one more day in space.

Landing attempts at KSC and Edwards Air Force Base in California are available.

The first Florida attempt would have a deorbit burn at 12:22 p.m. EST and a landing at 1:27 p.m. EST.

Read our landing delay story by Todd Halvorson posted at 2 p.m. EST

Payload bay door closing delayed a bit

Here we go again.

Unfortunately the situation looks about the same as it did on Sunday, when high crosswinds at the shuttle runway prevented Atlantis and its five astronauts from returning home.

Crosswinds still are a concern today. They already are blowing at the limit and the hope is that they will subside a bit as the day wears on.

However, an area of clouds and rain to the southeast of the Cape appears to be heading in this direction and could be over the landing facility at the time Atlantis is supposed to come down. Depending on how thick and dense those clouds are at the time, that may or may not be a problem.

Because of this uncertainty and in an effort to conserve supplies for later landing opportunities, the payload bay doors will remain open for a short while more. With the doors open, the radiators that line the doors can be used to cool the shuttle's systems. Once they are closed, a water-hungry flash evaporator system is used.

For now, the crew is aiming to fire its braking rockets at 12:21 p.m. EST and touchdown at KSC at 1:27 p.m. EST.

The second landing opportunity at KSC has the deorbit maneuver at 1:57 p.m. EST and landing at 3:03 p.m. EST.

Although there are two landing opportunities at Edwards Air Force Base in California today, and a shuttle ground team is on duty in case, the weather there doesn't look good.

We will update this page as soon as there is a decision on the first landing opportunity.

Astronauts close Atlantis cargo bay doors

The two 60-foot-long payload bay doors of shuttle Atlantis were reported closed at 10:10 a.m. EST, a few minutes later than planned this morning to allow the crew to conserve some water.

With the doors shut Mission Control is indicating its intention to go for the first landing opportunity at the Kennedy Space Center this afternoon, but the weather still isn't fully cooperating.

Crosswinds remain a concern and there is an area of low level clouds moving toward the Cape area that is expected over the shuttle runway right at the planned landing time of 1:27 p.m. EST.

As it was on Sunday, mission managers are hopeful that if the weather isn't acceptable for the first opportunity it will be for the second, when Atlantis would touch down on the runway at 3:03 p.m. EST.

Although there are two landing opportunities at Edwards Air Force Base in California today, and a shuttle ground team is on duty in case, the weather there doesn't look good.

We will update this page as soon as there is a decision on the first landing opportunity, that news likely coming right around noon EST.

Landing delayed again

The first landing opportunity today has been waived off for today. Approaching clouds and out-of-limits crosswinds are to blame.

The hope is that things will look better in an hour or so.

Right now the plan is to fire the orbital maneuvering engines at 1:58 p.m. EST, which would lead to a landing at 3:04 p.m. EST.

Weather is still an issue.

Although there are two landing opportunities at Edwards Air Force Base in California today, and a shuttle ground team is on duty in case, the weather there doesn't look good either.

Atlantis has enough supplies to support at least one landing attempt on Tuesday and Wednesday, and that situation could improve depending on the conservation efforts of the crew today.

Monday landing attempts called off

With weather at the Kennedy Space Center and Edwards Air Force Base unacceptable and little chance of it getting any better today, mission managers have told the Atlantis crew to remain in space yet another day.

Forecasts for landing in Florida, California and even White Sands in New Mexico on Tuesday are much better.

We'll update with more information later this afternoon.

Tuesday could be the day Atlantis returns

The five astronauts aboard Atlantis have finished backing out of their landing preparations today after gusting winds and threatening clouds over Kennedy Space Center prompted mission managers to call off the shuttle's return to Earth.

The crew is now enjoying some welcome opportunities to watch the blue planet 230 miles below.

Bed time will be 8:13 p.m. EST tonight and they will awaken at 4:13 a.m. EST Tuesday.

The exact timing of events such as payload bay door closure and the software switch to the landing program will depend on when Mission Control would like to make the first landing attempt to Florida.

On Tuesday there are two landing opportunities each at KSC and Edwards Air Force Base in California, and three landing opportunities at White Sands Space Harbor in New Mexico. The weather forecast looks favorable at all three sites.

Of the seven landing opportunities, flight director Leroy Cain said Monday the Mission Control team will pick the three best and make a run at them.

"Tomorrow will be an interesting day," Cain said. "We will find a landing site tomorrow where we are confident we can perform a safe landing."

In choosing the three best chances it is possible that NASA will ignore the first landing opportunity at KSC at 12:27 p.m. EST and go for the second opportunity at KSC, which is at 2:02 p.m. EST.

Cain also said that realistically a landing at the Northrup Strip at White Sands wasn't likely given the optimistic weather forecasts for Florida and California. "We're really not considering Northrup unless it's the only option left at the end of the day," he said.

Here's a table of all the possibilities:

                     Deorbit      Land                      (All times EST)Orbit 200   KSC      11:20 a.m.   12:27 p.m.Orbit 201   NOR      12:54  p.m.  1:59 p.m.            KSC      12:56 p.m.   2:02 p.m.Orbit 202   EDW      2:27 p.m.    3:33 p.m.            NOR      2:30 p.m.    3:35 p.m.Orbit 203   EDW      4:04 p.m.    5:09 p.m.            NOR      4:07 p.m.    5:11 p.m.

Look for our next update to this page around 8:30 a.m. EST Tuesday.

Atlantis payload bay doors closed again

For the third time in as many days, the Atlantis astronauts have closed the 60-foot-long payload bay doors as NASA mission managers hunt for a landing site for the shuttle today.

Clouds over the Kennedy Space Center were a threat for an initial landing opportunity today, and could still be a problem. If the skies remain clear enough to allow a safe landing, Atlantis would touch down at 2:02 p.m. EST. Crosswinds are not a problem today as they were on Sunday and Monday.

Clouds also might be a problem at Edwards Air Force Base in California. Although the skies are clear over the Mojave Desert now, things might thicken up a bit later this afternoon.

Shuttle mission commentator Kyle Herring reports that KSC remains the prime landing site and Edwards the backup. However, should it be needed, the White Sands runway could be used on the last landing opportunity of the day if weather in Florida and California doesn't remain clear.

Weather over the New Mexico site is said to be "pristine," according to Herring.

Here are the remaining landing options available for the crew today:

                     Deorbit      Land                      (All times EST)Orbit 201   KSC      12:56 p.m.   2:02 p.m.Orbit 202   EDW      2:27 p.m.    3:33 p.m.Orbit 203   EDW      4:04 p.m.    5:09 p.m.            NOR      4:07 p.m.    5:11 p.m.

California, here we come

A new "big picture" was just radioed up to the crew of shuttle Atlantis and it seems very likely that there will be no landing in Florida today, with flight controllers leaning toward sending the spaceplane to a landing at Edwards Air Force Base in California later this afternoon.

A line of clouds continues to move over the Cape from the ocean and chief astronaut Charlie Precourt is not finding much luck in finding an acceptable hole in the sky. Typically, the clouds drifting over the Cape are the only clouds doing so along Florida's Atlantic shore for a couple of hundred miles north and south.

Meanwhile, at Edwards, the chance of broken clouds over the Rogers Dry Lake site seems to be going away and astronaut Brian Duffy flying a T-38 training jet there is optimistic Atlantis will have no trouble landing there.

So while the Atlantis astronauts continue to prepare for a KSC landing at 2:02 p.m. EST, they've been told to pace themselves with the understanding that it is increasingly probable mission managers will cancel the remaining Florida opportunity today and turn their attention toward Edwards.

That official call is expected within the hour.

The remaining landing options available for the crew today are listed below, with the orbit 202 to Edwards opportunity now the most likely choice:

                     Deorbit      Land                      (All times EST)Orbit 201   KSC      12:56 p.m.   2:02 p.m.Orbit 202   EDW      2:27 p.m.    3:33 p.m.Orbit 203   EDW      4:04 p.m.    5:09 p.m.            NOR      4:07 p.m.    5:11 p.m.

It's definitely off to the high desert

NASA has decided to trade palm trees for Joshua trees.

Mission Control is now aiming to send shuttle Atlantis to Edwards Air Force Base in California where the weather is said to be acceptable for landing on the high desert of Southern California.

Despite a good forecast, the weather fell apart for a landing in Florida today thanks to low clouds and rain threatening the area. Chief astronaut Charlie Precourt flying a Shuttle Training Aircraft had no luck finding any safe holes in the sky over the Cape Canaveral area.

The most recent Edwards landing was Discovery last October at the conclusion of STS-92, when it took two days of Florida wave-offs before the shuttle was sent to California.

As a result of this latest news, the remaining landing options available for the crew today:

                     Deorbit      Land                      (All times EST)Orbit 202   EDW      2:27 p.m.    3:33 p.m.Orbit 203   EDW      4:04 p.m.    5:09 p.m.            NOR      4:07 p.m.    5:11 p.m.

Atlantis gets 'go' to come home

Atlantis has been given the "go" for the deorbit burn that will have the shuttle making a landing at Edwards Air Force Base in California at 3:33 p.m. EST.

The firing of the twin orbital maneuvering engines will come at 2:27 p.m. and last 2 minutes and 43 seconds.

Shuttle committed to hour-long glide home

Four days after undocking with the International Space Station, shuttle Atlantis and a crew of five astronauts are on their way home, committed to a landing at Edwards Air Force Base in California at 3:33 p.m. EST.

The de-orbit burn began at 2:27 p.m. EST and lasted 2 minutes and 43 seconds. The orbital maneuvering engine firing slowed Atlantis by 319 feet per second, just enough for the shuttle to be put on an hour-long supersonic dive through the atmosphere.

Once Atlantis reaches 400,000 feet it will officially re-enter Earth's atmosphere and begin a computer-controlled flight profile that will burn off enough energy to reach the Edwards airfield.

Once over the dry lakebed, commander Ken Cockrell will take manual control of the flying and steer Atlantis to line up with the concrete runway 22.

Weather at the time of landing: A headwind blowing nearly down the runway centerline at 12 knots, gusting to 20 knots; scattered clouds between 5,000 and 10,000 feet and nearly unlimited visibility.

A reminder that with no jet engines, Atlantis is a 100-ton glider that can only make one attempt at landing so everything has to go right.

You can watch the landing live on NASA TV courtesy of a video feed from SPACE.com.

Atlantis safely lands in California

Commander Ken Cockrell has brought Atlantis and his four crewmates home to a safe landing at Edwards Air Force Base in California, touching down on the concrete runway there at 3:33 p.m. EST.

Gusting crosswinds on Sunday and Monday, and clouds today, prevented a landing at the Kennedy Space Center, forcing Mission Control to send the shuttle to the alternate landing site on the West Coast.

Although clearly the safe thing to do, a consequence of the decision is that it will cost about $1 million and at least a week of extra work to prepare Atlantis for its next mission to the International Space Station, now targeted for June 8.

The extra time is the average it takes the team of KSC workers who are flown out to California to prepare the shuttle for its return to Florida riding atop a modified Boeing 747 jumbo jet. (For more information about the ferry flight see this story.)

This is the second landing at Edwards in the past four months. Discovery landed there in October after a similar situation in which bad weather persisted over Florida for three days in a row. Interestingly, Discovery's was the first California landing in more than three years.

The five Atlantis astronauts are expected to depart their spaceplane within the hour.

Shuttle shuffle ahead for NASA

All five astronauts are reported to be doing well after the conclusion of their spaceflight today in California. They are scheduled to return to the Johnson Space Center in Houston for a reunion with their families on Wednesday.

For a full wrap-up of what happened today, read this story from Cape Canaveral Bureau Chief Todd Halvorson.

In the meantime, NASA must now return Atlantis to the Kennedy Space Center riding atop a modified 747 jumbo jet. That trip is expected to begin in about a week.

Almost at the same time, NASA wanted to ferry Columbia from its Palmdale plant -- a long half-hour drive from Edwards -- to Florida this weekend, but that move may have to wait for Atlantis. Shuttle managers still are considering their options.

In any case, we will continue to update this page at least once a day until Atlantis is safely back at the Florida spaceport.

Columbia ferry flight delayed

Columbia's ferry flight home to Florida from California has been delayed at least a day thanks to stormy weather over Palmdale.

NASA's oldest orbiter was to have been rolled out of its factory hangar today in a ceremony turning the vehicle back over to NASA, but the threat of thunderstorms including hail prevented the event. Columbia's departure from the airfield will take place about 24 hours after it can be rolled out on to the tarmac.

It takes that long to lift the orbiter using cranes and securely fasten it to the top of a NASA 747 jumbo jet.

So the two-day ferry flight will be delayed day for day until Columbia makes it out of its hangar.

Of course, this is all pertinent to the effort to get Atlantis returned to Florida after it ended its mission to the International Space Station with a landing at Edwards Air Force Base on Tuesday. NASA managers decided to return Columbia first so the Atlantis team is watching this carefully.

Keep an eye on this page for updates.

Ferry flights still on hold for weather

Half of NASA's shuttle fleet remains stuck in California due to unacceptable weather there and along the planned flight path heading east.

The earliest the ferry flights now will begin is Thursday.

Columbia is atop its 747 carrier jet at Boeing's Palmdale plant awaiting clearance for takeoff, and Atlantis is nearby atop NASA's other 747 carrier jet at Edwards Air Force Base, where Atlantis landed last week after a mission to the International Space Station.

Columbia was scheduled to begin its trip on Saturday but the stormy weather has persisted all week.

But with Atlantis also now ready to go, and still containing residual propellant and other hazardous chemicals from its mission, managers would like to return Atlantis to the safer environment of its Orbiter Processing Facility here at Kennedy Space Center just as soon as it is safe to do so.

As a result, Atlantis will begin the two-day trip ahead of Columbia. It is possible both ferry flights will be in the air at the same time and NASA spokesman Bruce Buckingham said that won't be a problem because they were able to assemble two full ferry flight crews.

The only complicating factor in planning is that for security and logistical reasons, the two shuttles will not stop at the same fields enroute at the same time.

NASA still would like to return Columbia via Ellington Air Field in Houston for an overnight stop near the Johnson Space Center to give workers there a rare chance to see the spaceship they help manage.

Atlantis' stops will be less accessible to the public because of the hazardous chemicals still onboard, but folks still will be able to see the unusual spaceship/aircraft fly in and out of the airports, which are usually Air Force bases.

We will provide full details of the shuttles' trips home to Florida as soon as we know them. Keep an eye on this page.

Atlantis and Columbia depart for Florida

NASA's shuttle fleet at the Kennedy Space Center could be up to full strength as early as midday Friday now that both Columbia and Atlantis have begun their cross-country ferry flight home.

After spending more than a year at the Boeing shuttle plant in Palmdale, Calif., Columbia departed Air Force Plant 42 at 2:05 p.m. EST on its way to Dyess Air Force Base in Abilene, Texas. The air base is located in west central Texas, 183 miles west of Dallas.

TSgt. Jacqueline Boucher of Dyess says they've been told Columbia will arrive about 3:30 p.m. local time, and will be easily seen from the road that runs parallel to their main flight line. If there are any other opportunities for local residents to get a closer look at Columbia, she advises to check local news media who will be broadcasting live from the base.

Atlantis, meanwhile, departed Edwards Air Force Base at 2:37 p.m. EST for Altus Air Force Base, which is located 139 miles southwest of Oklahoma City, Oklahoma. The trip will take about three hours and 15 minutes.

Opportunities to see Atlantis from the air base's perimeter will be limited, with the best bet being Highway 62, according to base officials. Atlantis still contains toxic propellant and other hazardous chemicals following its recent mission to the International Space Station so the general public will not be allowed any close access.

Both shuttles will spend the night at their respective air bases before continuing on with their ferry flights on Friday. If the weather cooperates for both ships, Atlantis could arrive back at KSC around noon EST, with Columbia about 90 minutes later.

A stop for Columbia in Houston will not be possible because of weather, but a fly-over of downtown Tallahassee remains on the schedule for NASA's oldest orbiter.

Shuttles safe for the night in Texas, Oklahoma

Riding atop their own 747s, both Columbia and Atlantis are safely on the ground following their departure from California earlier today.

Columbia departed Air Force Plant 42 in Palmdale at 2:05 p.m. EST and arrived at Dyess Air Force Base at Abilene, Texas at 5:40 p.m. EST. It had spent 17 months at the Boeing shuttle factory for maintenance and upgrades.

Atlantis departed Edwards Air Force Base at 2:37 p.m. EST and arrived at Altus Air Force Base in Oklahoma at 5:45 p.m. EST. The shuttle is on its way home to Florida after concluding the STS-98 mission to the International Space Station.

Ferry flight managers with both shuttlecraft will take a look at the weather between their overnight fueling stops and the Kennedy Space Center and decide Friday morning if and how far the cross-country trip can continue.

It is hoped that both Columbia and Atlantis will be able to make it all the way back to the Florida spaceport, arriving within an hour of each other around 1 p.m. EST. An exact itinerary will be announced in the morning.

NASA managers continue to plan an overflight of downtown Tallahassee, Florida with Columbia.

We'll post more details when they are available Friday morning.

Columbia stuck, Atlantis waits for clearance

Morning weather briefings in Texas and Oklahoma at 8:30 a.m. EST have concluded and here's the latest about NASA's efforts to return two shuttles to Florida riding piggyback atop modified 747 jumbo jets:

Columbia will remain at Dyess Air Force Base in Abilene, Texas today. As a result, Tallahassee residents should not expect to see the ferry flight make a low pass over downtown until tomorrow at the earliest, if not Monday.

Atlantis is on hold at Altus Air Force Base in Altus, Oklahoma. Another weather briefing will be held at noon EST to decide if there's still a chance to get Atlantis back to Florida today.

Developing severe weather along the flight path between Texas and Florida is the concern.

We wil update this page again after the noon EST weather briefing.

Shuttles remain grounded halfway home

Shuttles Columbia and Atlantis will remain at their respective pit stops today in Texas and Oklahoma while waiting for bad weather ahead of them to clear.

The two orbiters are bolted to the top of NASA's two 747 jumbo jets and began their piggyback ferry flights home to the Kennedy Space Center from California on Thursday.

But a developing weather system in the U.S. southeast is making it difficult for the vehicles to make it any farther east. Although managers will assess the weather situation again early Saturday, it's more than a good bet to think that it will be Sunday or even Monday before either of the shuttles return home.

For now, Atlantis is safely at Altus Air Force Base in Altus, Oklahoma while Columbia is at Dyess Air Force Base in Abilene, Texas. Residents near those bases are strongly encouraged by this producer to take a drive and see the space shuttle sitting atop a 747. It's an unforgettable picture.

We will update this page following the weather briefings Saturday morning.

Weekend weather picture remains grim

The ferry flight story is quickly becoming a saga and has the potential to become a quest, if not an epic, very soon.

Severe weather hovering over the U.S. southeast continues to strengthen as the U.S. northeast braces for a March winter storm. Radar images show rain blocking the flight path to Kennedy Space Center from Texas and Oklahoma, where Columbia and Atlantis are this morning.

As a result, once again NASA managers have decided to keep the shuttle ferry flights grounded until it is safe to continue to the east.

Bolted atop NASA's two 747 jumbo jets, the shuttles began their piggyback ride home from two locations in California on Thursday. Columbia was to have begun its journey home one week ago today, while Atlantis was to have followed starting on Wednesday.

But with strict rules about how high the combination shuttle/jets can fly (a complex formula mostly involving air pressure and temperature) and what path they can take (absolutely no flight through rain), the weather basically must be clear, so at this time of year over the U.S. that can get difficult.

Rain and thunderstorms are forecast for Florida's Space Coast on Sunday.

For now, Columbia sits on the ramp at Dyess Air Force Base in Abilene, Texas. The air base is located in west central Texas, 183 miles west of Dallas. And Atlantis is at Altus Air Force Base, which is located 139 miles southwest of Oklahoma City, Oklahoma.

Weather permitting, NASA spokesman Bill Johnson reports that the two ships likely will be flown on Sunday to either Barksdale Air Force Base in Lousiana, Columbus Air Force Base in Mississippi or Eglin Air Force Base in Florida.

Our next update will come around noon EST Sunday, following the next weather briefing.

Atlantis to be moved again while Columbia waits

Space shuttle Atlantis is supposed to be on the move again riding piggyback atop its 747 jumbo jet, while Columbia waits to see what happens to Atlantis before continuing its cross-country journey home to the Kennedy Space Center.

Atlantis was to have left Altus Air Force Base in Oklahoma at 11:30 a.m. EST on its way to Barksdale Air Force Base in Louisiana, where it was scheduled to arrive 12:40 p.m. EST. Barksdale AFB is located near Shreveport in the Northwest corner of Louisiana just 18 miles east of the Texas border.

That's according to NASA spokesman Bill Johnson, who has not yet been able to confirm that Atlantis is actually in the air.

Once at Barksdale, managers will look at the weather situation to the east and are hopeful they will be able to continue on this afternoon to Eglin Air Force Base in North Florida.

Columbia's plan will depend on how far Atlantis makes it today. It might be flown from its present location at Dyess Air Force Base near Abilene, Texas to Barksdale or Eglin.

It doesn't appear that either shuttle will arrive at KSC today.

Because of Thursday's planned launch of Discovery, ramp space at KSC is a premium so it is likely that only one shuttle will be allowed at the KSC shuttle runway at a time. Since Atlantis has the priority, it is possible that Columbia will be flown to the Skid Strip at Cape Canaveral Air Force Station or be parked at nearby Patrick Air Force Base until Atlantis is removed from its 747 and towed to an orbiter processing facility hangar.

A strong line of thunderstorms is about to move through the Cape area, so this page will not be updated again until later this afternoon while our computers here are shut down.

Atlantis moves closer, Columbia sits still

Atlantis made it a little closer home to Florida today but Columbia remained in Texas.

According to NASA spokesman Bill Johnson, Atlantis this afternoon was flown atop its 747 carrier jet from Altus Air Force Base in Oklahoma to Barksdale Air Force Base near Shreveport, Lousiana. After a weather briefing and refueling, Atlantis' ferry flight was to depart Barksdale at 3:30 p.m. EST with plans to land at Eglin Air Force Base in North Florida at 5 p.m. EST.

Atlantis is scheduled to spend the night at Eglin and then finish the cross-country trip home Monday morning. It should take about an hour to make the trip to Florida's Space Coast and the traditional low pass along the Atlantic beaches here in Brevard County is expected.

Columbia, meanwhile, is expected to depart Dyess at 9:30 a.m. EST. It is not clear if Columbia will make a refueling stop, or whether the previously planned fly over of downtown Tallahassee in Florida is still on the flight plan.

It also is expected that when Columbia arrives over the Florida spaceport it will land at Patrick Air Force Base or at the Skid Strip at Cape Canaveral Air Force Station. The reason: ramp space at KSC will be limited with the presence of Atlantis and the support vehicles for Thursday's planned launch of shuttle Discovery.

Once Atlantis is removed from its 747 and towed to a processing hangar, Columbia will be allowed its turn on the tarmac.

Our next update to this page will come Monday morning once the day's flight plan is announced.

In the meantime, look for our STS-102 mission coverage to begin with a mission preview story from Cape Canaveral Bureau Chief Todd Halvorson that we will post at 7 a.m. EST Monday, eight hours after the Discovery crew is scheduled to arrive at KSC for the start of the final three-day countdown.

Atlantis heading to KSC, Columbia isn't yet

Atlantis is expected over the Kennedy Space Center around 11 a.m. EST this morning. Riding piggyback atop its 747 carrier jet, Atlantis is expected to touch down at the Shuttle Landing Facility at 11:20 a.m. EST, officially concluding the STS-98 mission and beginning the process of preparing Atlantis for its next mission in June.

At the moment Atlantis is at Eglin Air Force Base in North Florida.

Columbia, meanwhile, still is at Dyess Air Force Base near Abilene, Texas. There was hope that they could continue the ferry flight home this morning but the initial weather briefing didn't look good, so another look is expected at this hour.

If Columbia is able to make it all the way here to Florida today it likely will be landed either at the Skid Strip of Cape Canaveral Air Force Station or the field at Patrick Air Force Base. That's because the amount of ramp space at KSC is limited due to the support requirements for shuttle Discovery's planned launch on Thursday.