BY JUSTIN RAY

April 23, 2000 -- February's flight of space shuttle Endeavour on an 11-day radar mapping mission is recorded here in this archive of our mission coverage.

See our current Mission Status Center for updates on space shuttle Atlantis' mission to the International Space Station scheduled for launch April 24.

WEDNESDAY, FEBRUARY 23, 2000

Endeavour's six astronauts say they are pleased with their Earth radar mapping mission that ended on Tuesday night. The 11-day flight mapped about 47.6 million square miles of the planet with a sophisticated radar system, covering 99.958 percent of the planned mapping area at least once and 94.594 percent of it twice. "That's an A+ on anybody's report card. So we're really pleased with the outcome of this mission," commander Kevin Kregel told reporters Wednesday morning.

The data stored on 332 high-density tapes will be used by researchers to generate the finest 3D map of the Earth's surface. "It will be a very good present from 20th century to 21st century people all over the world," said Endeavour astronaut Mamoru Mohri of Japan's space agency.

The astronauts flew back to their home base in Houston after the news conference at Kennedy Space Center's press site.

Meanwhile, space shuttle Endeavour was towed from the Shuttle Landing Facility runway to Orbiter Processing Facility bay 2 a few hours after touchdown. NASA said the shuttle was in the hangar by 1:34 a.m. EST (0634 GMT). The shuttle will now undergo routine post-flight deservicing and inspections before work starts to prepare the craft for its next journey into space in November.

This will complete our Mission Status Center coverage of STS-99.

0430 GMT (11:30 p.m. EST)

Read our landing story for a summary of Endeavour's return to Earth. Also, we have posted a video clip of Endeavour's landing. The QuickTime file runs 26 seconds.

Here are the preliminary landing times:

Main gear touchdown
6:22:23 p.m. EST
MET of 11 days, 5 hours, 38 minutes, 43 seconds

Nose gear touchdown
6:22:34 p.m. EST
MET of 11 days, 5 hours, 38 minutes, 54 seconds

Wheels stop
6:23:25 p.m. EST
MET of 11 days, 5 hours, 39 minutes, 45 seconds

We will update the STS-99 Mission Status Center for a final time around midday Wednesday once the astronauts depart KSC.

0043 GMT (7:43 p.m. EST)

The six astronauts have departed the Shuttle Landing Facility at Kennedy Space Center. They are taking the 20-minute ride to KSC's Operations & Checkout Building, which serves as the crew quarters. The astronauts will spend the night in Florida. A press conference with the crew is planned for 9:30 a.m. EST (1430 GMT) Wednesday at KSC before the astronauts return to their homes in Houston.

Workers plan to tow space shuttle Endeavour from the runway to Orbiter Processing Facility bay 2 in about two hours. In the OPF hangar Endeavour will undergo safing and post-flight deservicing. In a few weeks, NASA will begin preparing the shuttle for its next mission -- the STS-97 mission to deliver solar arrays to the International Space Station in November.

We have posted a video clip of Endeavour's landing. The QuickTime file runs 26 seconds.

Check back later tonight for a landing wrap-up story and images.

0027 GMT (7:27 p.m. EST)

The crewmembers have left the transport vehicle and are beginning the walkaround the shuttle, kicking the tires and looking at the spacecraft they called home for the past 11 days. Various members of senior NASA management including Administrator Dan Goldin are welcoming the shuttle astronauts on the runway.

0005 GMT (7:05 p.m. EST)

All six of Endeavour's astronauts have left the shuttle. They are currently inside the motorized Crew Transport Vehicle. It is expected that at least some of the astronauts will make the traditional walkaround of the shuttle on the runway shortly. Later, the astronauts will head to Kennedy Space Center's Operations & Checkout Building to be reunited with their families and spend the night. A press conference with the crew is planned for 9:30 a.m. EST (1430 GMT) Wednesday at KSC before the astronauts return to their homes in Houston.

TUESDAY, FEBRUARY 22, 2000
2347 GMT (6:47 p.m. EST)

The Crew Transport Vehicle -- a modified airport "People Mover" -- has pulled into position next to Endeavour's crew hatch. The CTV features beds and comfortable seats for the astronauts to receive medical checks and get their balance after returning to Earth's gravity from the weightless environment of space.

2338 GMT (6:38 p.m. EST)

Mission Control just told the Endeavour astronauts they can take off their day-glo orange launch and entry spacesuits. The crew should exit the shuttle within the next 40 to 45 minutes.

2337 GMT (6:37 p.m. EST)

Pilot Dom Gorie has turned off Endeavour's Auxiliary Power Units.

2333 GMT (6:33 p.m. EST)

The astronauts are going through standard post-landing safing of Endeavour. The main engine nozzles are being moved to the "rain drain" position and the external tank umbilical doors have been opened.

Live television views show a plume of exhaust shooting up from the Auxiliary Power Units on the tail of Endeavour. This is seen on previous landings but the color and extent tonight is like nothing in the past. NASA says it more pronounced tonight due to the lighting conditions on the runway.

2323 GMT (6:23 p.m. EST)

WHEELS STOP. Endeavour has rolled to a stop at Kennedy Space Center following the successful mission to map the Earth in 3D with a clarity never before achieved.

2322 GMT (6:22 p.m. EST)

TOUCHDOWN! Main gear touchdown. Nose gear touchdown. Drag chute deployed. Space shuttle Endeavour rolls out on Runway 33 at the Kennedy Space Center to complete the first human space flight of the new millennium.

2322 GMT (6:22 p.m. EST)

Wheels down and locked. Standing by for touchdown on Kennedy Space Center's Runway 33.

2322 GMT (6:22 p.m. EST)

Orbiter flaring up.

2321 GMT (6:21 p.m. EST)

Wings are level. Speed 380 miles per hour. One minute to touchdown.

2320 GMT (6:20 p.m. EST)

Field in sight. Kevin Kregel can see the runway.

2319 GMT (6:19 p.m. EST)

Endeavour is in the heading alignment cone, an imaginary circle to align with Runway 33. Kevin Kregel will make a 194-degree right overhead turn. Speed is 550 miles per hour.

2318 GMT (6:18 p.m. EST)

Commander Kevin Kregel has taken manual control of Endeavour. The sonic booms have been heard at KSC, announcing the shuttle's arrival.

2316 GMT (6:16 p.m. EST)

Endeavour's wings are level. Mission Control says the drag chute will not be deployed until after nose gear touchdown due to stiff crosswinds at KSC.

2316 GMT (6:16 p.m. EST)

Just under 6 minutes to landing. Speed 1,300 miles per hour, distance from the runway is 68 miles.

2314 GMT (6:14 p.m. EST)

The final roll command has been issued by Endeavour's computers. Air data probes have been deployed from the shuttle's nose to feed information to the computers.

2312 GMT (6:12 p.m. EST)

Mission Control reports Endeavour is right on track for landing. The shuttle is predicted to touch down on runway 33 at a speed of 205 knots, about 2,500 feet down the three-mile-long landing strip.

2311 GMT (6:11 p.m. EST)

The TACAN navigation units aboard Endeavour are now receiving data from beacons located at the runway at Kennedy Space Center. Also, long-range tracking cameras at the Cape have spotted the shuttle.

2311 GMT (6:11 p.m. EST)

Endeavour's speed is down to Mach 11. The shuttle is 400 miles from KSC. Now reversing the steering bank back to the left.

2310 GMT (6:10 p.m. EST)

Now 12 minutes to touchdown. Endeavour is flying about 30 miles above northwestern Georgia headed for Kennedy Space Center in Florida.

2306 GMT (6:06 p.m. EST)

Communications with Endeavour have been restored. The shuttle is now banking to right, the second of four rolls during entry designed to reduce speed. Velocity currently 12,000 miles per hour at an altitude of 39 miles. Endeavour is currently over Illinois.

2304 GMT (6:04 p.m. EST)

Endeavour is currently in a communications blackout period due to the plasma trail it is creating during a series of speed scrubbing rolls. This blackout will continue for a few more minutes.

2322 GMT (6:02 p.m. EST)

Now 20 minutes to touchdown on runway 33 at Kennedy Space Center, Florida.

2257 GMT (5:57 p.m. EST)

The space shuttle is currently in the first of four planned banks to scrub off speed as it plunges into the atmosphere. This is a turn to the left. These rolls basically remove the energy Endeavour built up during launch.

Endeavour is currently at altitude of 47 miles with a speed over 16,000 miles per hour.

2256 GMT (5:56 p.m. EST)

All is reported in readiness at Kennedy Space Center for landing at 6:22 p.m. EST where the sun is setting. It is a beautiful postcard Florida evening. The landing convoy team members began gathering at 1:30 p.m. EST and received a safety briefing at 3:15 p.m. EST. The team is currently deployed and are ready to support post-landing work to safe the shuttle after wheels stop. Endeavour will be towed to its hangar about three hours after landing.

2253 GMT (5:53 p.m. EST)

In the next few minutes, Endeavour will arrive over in North America along southern Alaska and Canada's western Pacific coastline. Following a southeastward curve through Canada, the shuttle will make landfall in the continental U.S. over North Dakota, and continuing toward Kennedy Space Center by passing above Minnesota, eastern Iowa, through the heart of Illinois, western Kentucky, central Tennessee, the northeastern tip of Alabama, southwest Georgia and streaking southward above the middle part of the Florida pensinsula. Endeavour will make an eastward turn toward KSC, flying past the coastline and over the Atlantic Ocean. Once over the ocean, the shuttle will make a 194-degree right-overhead turn to align with runway 33, which extends from the southeast to northwest.

2250 GMT (5:50 p.m. EST)

The protective tiles on the belly of Endeavour are now feeling heat beginning to build as the orbiter enters the top fringes of the atmosphere -- a period known as Entry Interface. The shuttle is flying with its nose elevated 40 degrees, wings level, at an altitude of 400,000 feet, passing over the extreme western Pacific Ocean just east of Asia, about 4,500 nautical miles from the landing site. Touchdown is set for 6:22 p.m. EST at Kennedy Space Center in Florida.

2238 GMT (5:38 p.m. EST)

All three Auxiliary Power Units are running to supply pressure to the shuttle's hydraulic systems, which in turn move Endeavour's aerosurfaces and deploy the landing gear. One unit was started prior to the deorbit burn; the others just a few moments ago. Mission Control reports seeing good pressures in all three APUs. The units are only activated during the launch and landing phases of the shuttle mission.

2230 GMT (5:30 p.m. EST)

Commander Kevin Kregel is now maneuvering Endeavour from its upside down, tail-forward position needed for the deorbit burn to the reentry configuration of heads-up and nose-forward. In this new position, the black tiles on the shuttle's belly will shield the spacecraft during the fiery plunge through the Earth's atmosphere.

2227 GMT (5:27 p.m. EST)

Endeavour has successfully completed the deorbit burn, committing the shuttle for its return to Earth. Landing is scheduled for 6:22 p.m. EST (2322 GMT) on runway 33 at Kennedy Space Center.

Today's landing will be the 21st consecutive to occur at Kennedy Space Center dating back to May 1996 and the 28th of the last 29 shuttle missions. KSC is the most used landing site for the space shuttle program with this the 50th touchdown. Edwards Air Force Base in California has seen 45 landings and White Sands in New Mexico supported one.

2225 GMT (5:25 p.m. EST)

Flying upside down and backwards over the Indian Ocean, northwest of Australia, space shuttle Endeavour has begun the deorbit burn for return to Earth. The firing of the two OMS engines on the tail of the shuttle will last two-minutes, 19 seconds, slowing the craft by about 248 feet per second. The retro-burn will send Endeavour toward a touchdown at 6:22 p.m. EST on a runway just miles from the Kennedy Space Center launch pad where the shuttle lifted off 11 days ago.

2223 GMT (5:23 p.m. EST)

Two minutes to the deorbit burn. Endeavour has been maneuvered to the proper attitude for the engine firing.

2211 GMT (5:11 p.m. EST)

Endeavour has started maneuvers to the deorbit burn attitude in space. The shuttle will be flying upside-down and backwards with its tail pointed in the direction of travel. The upcoming burn, now 14 minutes away, will slow Endeavour below orbital velocity.

2200 GMT (5:00 p.m. EST)

The crosswinds have eased at Kennedy Space Center and space shuttle Endeavour has been cleared for a sunset landing today at 6:22 p.m. EST (2322 GMT). Entry flight director John Shannon made the decision moments ago in Mission Control. Winds at the three-mile-long KSC shuttle runway are currently from the northeast at 10 gusting to 15 knots, right at the 15-knot safety limit.

"Endeavour, Houston. Go for the deorbit burn," astronaut Rick Sturckow radioed from Houston. "OK, thank you, good news. Go for the burn," Endeavour commander Kevin Kregel replied.

Endeavour will begin the two-minute, 19-second deorbit burn at 5:25:10 p.m. EST about 150 miles above the Indian Ocean. The maneuver will slow the shuttle's speed enough to drop Endeavour from orbit, beginning an hour-long dive back towards a pin-point landing in Florida.

2155 GMT (4:55 p.m. EST)

Now 30 minutes away from the firing of Endeavour's twin orbital maneuvering system engines to slow the shuttle from its orbit 150 miles above Earth. The astronauts will perform the burn only if weather conditions become acceptable at the Kennedy Space Center landing site. Mission Control is expected to decide in the next 10 minutes whether Endeavour can land at KSC today, with touchdown expected at 6:22 p.m. EST (2322 GMT).

2144 GMT (4:44 p.m. EST)

Endeavour's kitchen and toilet have been deactivated by the shuttle astronauts, completing the deorbit preparation checklist.

Crosswinds are being monitored at Kennedy Space Center. Also, chief astronaut Charlie Precourt is flying the Shuttle Training Aircraft around the Cape to check the weather conditions Endeavour would encounter during approach to the runway. Shortly, Precourt will head further away from KSC to examine some clouds streaming into east-central Florida from the Atlantic Ocean.

2130 GMT (4:30 p.m. EST)

Mission Control continues to watch the weather at Kennedy Space Center in Florida. A "go/no go" decision will be made within the hour on whether Endeavour will be able to land at KSC at 6:22 p.m. EST.

2111 GMT (4:11 p.m. EST)

Astronaut communicator Rick Sturckow in Mission Control just informed Endeavour's crew that crosswinds at Kennedy Space Center are definitely decreasing.

With this in mind, the shuttle astronauts were told to begin fluid loading, which is a procedure where the crewmembers get as much fluid as they can in their bodies to replace that lost in space, helping the readaptation to Earth's gravity. The loading typically lasts the one hour before the deorbit burn.

2100 GMT (4:00 p.m. EST)

Mission Control has just given Endeavour commander Kevin Kregel the latest numbers and data for today's second landing opportunity today at Kennedy Space Center. If the weather cooperates, the astronauts will fire the shuttle's twin orbital maneuvering system engines for two minutes and 19 seconds beginning at 5:25:10 p.m. EST (2225:10 GMT). The burn will slow Endeavour by about 248 feet per second, enough to drop the 110-ton shuttle from orbit to start the hour-long dive through Earth's atmosphere. Endeavour should begin feeling the upper fringes of the atmosphere at about 5:50 p.m. EST at an altitude of 372,000 feet. At 6:19 p.m. EST, commander Kevin Kregel will make a 194-degree right-overhead turn to align Endeavour with Kennedy Space Center's Runway 33. Touchdown should occur 2,400 feet down the runway at 205 knots at 6:22:26 p.m. EST (2322:26 GMT).

Crosswinds at KSC's Shuttle Landing Facility are forecasted to decrease slightly this afternoon, giving NASA some hope of Endeavour being able to land in Florida at the second of today's two opportunities there. If weather remains "no go" in Florida today, NASA will likely send Endeavour to the backup landing site at Edwards Air Force Base in California.

2030 GMT (3:30 p.m. EST)

Entry flight director John Shannon has just scrapped the first landing opportunity today for space shuttle Endeavour's return to Earth. Mission Control says crosswinds at Kennedy Space Center's shuttle runway are currently 13 peaking to 19 knots, above the limit of 15 knots. In addition, chief NASA astronaut Charlie Precourt flying the Shuttle Training Aircraft for weather reconnaissance at KSC reported turbulance below 500 feet.

"Endeavour, you are no go for the deorbit burn," astronaut communicator Rick Sturckow radioed from Mission Control in Houston.

Endeavour will now remain in space for one additional orbit. Weather forecasters say the crosswinds should decrease for the next landing opportunity into KSC. If conditions become acceptable, Endeavour will fire its orbital maneuvering system engines at 5:23:40 p.m. EST (2223:40 GMT), breaking the shuttle from Earth orbit. Touchdown would occur at 6:22:26 p.m. EST (2322:26 GMT).

2012 GMT (3:12 p.m. EST)

Endeavour's astronauts report their deorbit preparation checklist has been completed with the exception of deactivating the shuttle's kitchen and toilet. Those tasks won't be completed until after Mission Control tells the crew to begin "fluid loading" -- a process in which the astronauts drink lots of fluids to help readapt to Earth's gravity.

In the last few minutes, the astronauts have completed routine gimbal checks of Endeavour's twin orbital maneuvering system engine nozzles and prestarted the shuttle's Auxiliary Power Units used by the hydraulic systems.

Although it is not official, entry flight director John Shannon is likely to pass up the first landing opportunity today at Kennedy Space Center due to concerns over low clouds and gusty crosswinds. Officials continue to hope weather conditions will improve for the second KSC landing option today, which would start with a deorbit burn at 5:23:40 p.m. EST (2223:40 GMT) and touchdown at 6:22:26 p.m. EST (2322:26 GMT).

If Florida's weather does not cooperate with NASA today, the space agency could send the shuttle to Edwards Air Force Base in California where conditions are acceptable. The single Edwards opportunity on orbit 182 would start with a deorbit burn at 6:50:40 p.m. EST (2350:40 GMT) and landing at 7:48:08 p.m. EST (0048:08 GMT)

1935 GMT (2:35 p.m. EST)

Endeavour's six astronauts and ground controllers are pressing ahead with plans to bring the shuttle home today at the Kennedy Space Center if the weather cooperates. However, the crew was told to hold off on fluid loading. This is a procedure where the crewmembers get as much fluid as they can in their bodies to replace that lost in space, helping the readaptation to Earth's gravity. The loading typically lasts the one hour before the deorbit burn.

At this point, Mission Control has not waved off the option to send Endeavour toward an on-time landing at 4:50 p.m. EST (2150 GMT) if crosswinds at the KSC runway are within limits. The forecast currently calls for the winds to be above the 15-knot limit.

Mission Control is expected to make its "go/no go" decision on the first landing opportunity in about one hour from now. If Endeavour is cleared for landing, the shuttle's twin orbital maneuvering system engines will fire for two minutes and 21 seconds beginning at 3:53 p.m. EST. The deorbit burn will slow the ship's speed enough to send Endeavour back into Earth's atmosphere.

If the weather does not clear in time for the first landing opportunity, NASA will keep Endeavour in space for another orbit. The second and last chance to land in Florida today will begin with a deorbit burn at 5:23 p.m. EST (2223 GMT) and touchdown at 6:22 p.m. EST (2322 GMT).

1900 GMT (2:00 p.m. EST)

Mission Control has told Endeavour's astronauts to begin suiting up on schedule in hopes weather will allow the shuttle to return to Earth today. Officials want the crew to stay on the planned timeline today.

Weather remains a concern for the planned 4:50 p.m. EST (2150 GMT) landing time at Kennedy Space Center. However, forecasters are becoming more optimistic conditions will improve to allow landing during the second opportunity at 6:22 p.m. EST (2322 GMT) at KSC.

1850 GMT (1:50 p.m. EST)

The astronauts have closed the star tracker doors on Endeavour's nose in advance of today's fiery plung back through the atmosphere towards landing.

Mission Control is becoming more optimistic that weather conditions will allow landing at Kennedy Space Center today during the second opportunity at 6:22 p.m. EST (2322 GMT).

1839 GMT (1:39 p.m. EST)

Mission Control just informed Endeavour's astronauts that the weather is improving at Kennedy Space Center for landing today. Meteorologists are still watching gusty crosswinds at the three-mile-long shuttle runway. Officials believe weather conditions will be better during the second of two landing opportunities today at KSC. The first option would lead to a landing at 4:50 p.m. EST (2150 GMT) on orbit 180; the second at 6:22 p.m. EST (2322 GMT) on orbit 181.

In space, the astronauts have switched Endeavour's flight computers from the on-orbit to the entry software called OPS-3.

1817 GMT (1:17 p.m. EST)

Endeavour's two 60-foot long payload bay doors have been closed and locked in preparation for today's return from space. Activities remain on track to support a landing at 4:50 p.m. EST (2150 GMT) at Kennedy Space Center, weather permitting.

Upcoming in the next few minutes, the astronauts will transition Endeavour's onboard computers from the OPS-2 on-orbit software to the OPS-3 package for landing. In about 75 minutes, the crew will don their day-glo orange launch and entry spacesuits.

1807 GMT (1:07 p.m. EST)

Entry flight director John Shannon, after polling his team of flight controllers, has given the "go" to close Endeavour's payload bay doors. Shuttle commander Kevin Kregel says the crew will begin the task now. The port door will be closed first.

1750 GMT (12:50 p.m. EST)

Aboard space shuttle Endeavour the astronauts are continuing to step through their deorbit preparation checklist. Over the past hour, the crew maneuvered Endeavour into the "cold soak" attitude to thermally condition the craft for entry and verified switches in the cockpit were in the correct positions. At this point, the astronauts are deactivating equipment no longer needed, reinstalling the mission specialist seats and stowing away other materials in the crew module.

Mission Control will make a decision shortly whether to close Endeavour's payload bay doors on schedule at about 1:15 p.m. EST (1815 GMT).

At the prime landing site, chief NASA astronaut Charlie Precourt is flying a T-38 jet around the Kennedy Space Center area for weather reconnaissance. His reports on crosswinds, low clouds and nearby rainshowers will be added to discussions at Mission Control about the KSC weather conditions. The official forecast continues to show a "no go" status for KSC today for the landing opportunities at 4:50 p.m. EST (2150 GMT) and 6:22 p.m. EST (2322 GMT).

1650 GMT (11:50 a.m. EST)

The astronauts aboard shuttle Endeavour have entered their deorbit preparation timeline for today's planned entry and landing.

Officials at Mission Control in Houston, however, are keeping a very close eye on weather conditions at the preferred landing site at Kennedy Space Center, Florida. Conditions at the Cape are currently forecasted "no go" due to low clouds and gusty crosswinds. Meteorologists also report rainshowers are building over the Atlantic Ocean, just east of KSC. But those rainshowers, the weather folks say, could break the flow of clouds toward shore, potentially allowing Endeavour to head back to Florida today.

NASA has two opportunities on consecutive orbits to land Endeavour at KSC: 4:50 p.m. EST (2150 GMT) and 6:22 p.m. EST (2322 GMT).

If the KSC weather does not cooperate today, NASA will likely divert Endeavour to the alternate landing site at Edwards Air Force Base in California where conditions are forecasted to be acceptable. Landing there would occur at 7:48 p.m. EST (0048 GMT).

The weather forecast for KSC and Edwards on Wednesday looks poor, so NASA wants to bring Endeavour back to Earth today.

0350 GMT (10:50 p.m. EST)

Space shuttle Endeavour's astronauts are setting their sights on returning to Earth today after mapping a vast majority of the planet, but where the shuttle lands in anyone's guess. Read our complete landing preview story for further details.

We will provide continuous live updates throughout the day as NASA prepares to bring Endeavour home.

MONDAY, FEBRUARY 21, 2000
1923 GMT (2:23 p.m. EST)

Endeavour's astronauts have sucessfully completed the routine Flight Control System checkout. They tested an Auxiliary Power Unit, flight control surfaces and reaction control system jets for tomorrow's planned return to earth. All systems were found to be in good shape.

Both Kennedy Space Center and Edwards Air Force Base will be "called up" for landing support on Tuesday. However, the weather in Florida is forecast to be "no-go" for the next three days. Edwards will have acceptable weather tomorrow, but conditions there will deteriorate on Wednesday and Thursday.

1812 GMT (1:12 p.m. EST)

The shuttle crew has successfully test fired one of Endeavour's Auxiliary Power Units as part of the routine pre-landing Flight Control System checkout.

1743 GMT (12:43 p.m. EST)

Endeavour could be diverted to its backup landing strip in California because of poor weather expected at Florida's Kennedy Space Center, Capcom Chris Hadfield told Endeavour commander Kevin Kregel a few moments ago.

"The prognosis for weather for KSC is bad for Tuesday, Wednesday and Thursday, so that's making us look a little harder at the Edwards opportunity on the first day and right now it is our only viable option," Hadfield said.

Both gusty crosswinds and cloudy skies are expected to be a problem for a landing in Florida. The weather at Edwards is forecast to deteriorate in after Tuesday.

1628 GMT (11:28 a.m. EST)

Endeavour's astronauts are now beginning to deactivate the Shuttle Radar Topography Mission payload that mapped nearly 80 percent of the Earth's surface over the last 9 days.

We have posted a video clip of the radar antenna mast failing to latch during the first attempt. The QuickTime file runs 42 seconds.

Once SRTM is buttoned up shortly, the astronauts will turn their attention to checking Endevour's flight control systems and jet thrusters for Tuesday's scheduled reentry and landing.

Plans call for the shuttle to fire its twin orbital maneuvering system engines tomorrow at 3:52 p.m. EST (2052 GMT) for the deorbit orbit burn, beginning the hour-long glide through Earth's atmosphere. Touchdown at Kennedy Space Center in Florida to conclude the 11-day STS-99 mission is expected at 4:50 p.m. EST (2150 GMT).

NASA has two backup landing opportunities on Tuesday. The first will occur at KSC one orbit later with a touchdown at 6:22 p.m. EST (2322 GMT). The last of the day will come at the alternate landing site -- Edwards Air Force Base in California -- at 7:48 p.m. EST (0048 GMT).

The weather forecast shows suspect conditions at KSC and Edwards. Meteorologists say KSC will see scattered clouds at 4,000 and 25,000 feet, 7 miles of visibility and northeasterly winds at 13 peaking to 20 knots. There will be some concern of crosswind violation and the clouds becoming broken at 4,000 feet that would constitute a ceiling. Edwards looks fine with scattered clouds at 5,000 feet, broken at 12,000 feet, and overcast of 20,000 feet, visibility of 7 miles, southwesterly winds at 12 peaking to 18 knots.

NASA will hold the traditional pre-landing news conference at 4 p.m. EST (2100 GMT) today. We will post a full landing preview later this evening.

1602 GMT (11:02 a.m. EST)

Astronaut Janice Voss says mast stowage has been completed and the latches are indeed locked. There was some drama this morning 150 miles above the Earth, but after 2 1/2 hours, the 197-foot long accordion-like radar mast has been returned to its canister for the trip back to Earth tomorrow.

1557 GMT (10:57 a.m. EST)

The Endeavour astronauts report the latches are indicated in the lock position. Mission Control is putting together the next few steps in the procedure. Shortly, the radar system and carrier pallet will be deactivated in preparation for tomorrow's entry and landing of Endeavour.

1550 GMT (10:50 a.m. EST)

The mast canister is closed! The third re-stow attempt has worked and applause is heard in Mission Control.

1542 GMT (10:42 a.m. EST)

Mission Control has just told the astronauts to repeat the last plan with some modification to close and lock the mast canister in the Endeavour's payload bay. The plan calls for the two drive motors to be turned on at full torque, pulling the mast into the can for 15 seconds. If the canister lid still does not latch, the effort will be repeated two additional times in five minute intervals. It is still suspected that cables running inside the mast are stiff and causing the inch or so gap between the canister's lid and mouth. But with more heat, the cables could loosen up a bit, officials say.

1523 GMT (10:23 a.m. EST)

To summarize the situation this morning, the 197-foot long accordion-like radar mast was reeled into its 9-foot long canister about two hours ago following the completion of mapping operations. However, the mast did not retract fully, stopping an inch or two short. The canister's lid failed to close and latch as a result. Two further attempt to power the mast inside its can have been unsuccessful. NASA has said it needs two of the three latches to be locked to keep the mast in place for Endeavour to return to Earth. Mission Control is discussing its options, which does include jettisoning the mast and canister into space.

See our earlier Mission Status Center coverage of STS-99.