BY JUSTIN RAY

Follow the landing of NASA's "Spirit" Mars Exploration Rover-A on the Red Planet! Reload this page for the very latest on the mission.

SUNDAY, JANUARY 25, 2004
The group working to unravel the glitch with Spirit and return the rover to action has narrowed the possible cause of its trouble to three potentials. Read our full story.

2116 GMT (4:16 p.m. EST)
Science leader Steve Squyres says Opportunity has scored a 300-million-mile hole in one!

As suspected overnight when the first images arrived on Earth, the rover has landed inside "a 20-meter diameter" crater, Squyres reports. The crater is estimated to be "a couple of meters deep." Therefore, it should not be a challenge for the rover to drive out, he said.

A much larger crater, seen in the descent camera images, is near the lander and likely within reach of Opportunity to explore.

2106 GMT (4:06 p.m. EST)
"Spirit is still serious but we are moving toward guarded condition now," rover project manager Pete Theisinger reports. "I think we got a patient well on the way to recovery."

In the past day, engineers have determined that Spirit's flash memory hardware is OK. A leading theory today is that a portion of the rover's software simply couldn't cope with all that was happening on Wednesday when the trouble began.

The rover's batteries are now fully charged and the craft shortly will be going to sleep for the night. But before nighttime it will be relaying data to the Mars Odyssey orbiter including engineering and diagnostic information.

Theisinger predicts that Spirit will resume driving around the surface in a couple of weeks.

Meanwhile, the Opportunity rover is operating properly following its landing last night.

2050 GMT (3:50 p.m. EST)
You can see the descent camera images here.

2034 GMT (3:34 p.m. EST)
The Opportunity rover appears to be in good condition, according to the health data just received. There have been no new fault errors and no reports from flight controllers of any problems.

A NASA news conference is upcoming at 4 p.m. EST.

2029 GMT (3:29 p.m. EST)
All three of the descent images have been received showing the approaching martian surface as Opportunity neared touchdown last night. The pictures will help scientists and engineers pinpoint the rover's exact landing site.

2015 GMT (3:15 p.m. EST)
There has been a short break in Odyssey's playback of the data. More information is expected in a little while.

2008 GMT (3:08 p.m. EST)
The descent images are arriving now.

2006 GMT (3:06 p.m. EST)
About 22.9 megabits of data has been received by Odyssey from the Opportunity rover.

2004 GMT (3:04 p.m. EST)
New images of the Opportunity rover are rolling into Mission Control, including a Pancam image of the strange tiled features near the lander.

1954 GMT (2:54 p.m. EST)
Mars Odyssey has indeed received data from Opportunity, engineers report. That info is being beamed to Earth.

1950 GMT (2:50 p.m. EST)
Senior officials are arriving in Mission Control to see what Opportunity tells Earth, including JPL director Charles Elachi, rover project manager Pete Theisinger and scientist Steve Squyres.

1940 GMT (2:40 p.m. EST)
The data relay session between the Mars Odyssey orbiter and Opportunity rover should be occurring at this time. The information will be arriving on Earth shortly.

Mission Control says the data bundle should include the pictures from the lander's descent imaging camera showing the surface just prior to touchdown.

1215 GMT (7:15 a.m. EST)
It is nighttime at Opportunity's Meridiani landing site. The rover sleeps during the night to conserve power, but it will wake up for a short time to transmit data to NASA's Mars Odyssey orbiter when it flies overhead at about 2:30 p.m. EST today.

We will update this page when information becomes available from the Odyssey pass.

The next rover news conference is scheduled for 4 p.m. EST.

1140 GMT (6:40 a.m. EST)
The Opportunity rover unfolded its solar panels and beamed back its first snapshots of Mars four hours after landing today, providing stunning views of nearby slab-like rock formations, the first bedrock ever seen on the red planet. The images also showed what to this point is the smoothest fine-grain soil ever seen on Mars. Read our full story.

1105 GMT (6:05 a.m. EST)
Color imagery of Meridiani Planum is here.

1020 GMT (5:20 a.m. EST)
Scientists say they have hit the jackpot with Opportunity's exotic, alien landing site. It appears nothing like the previous robotic landing locales on the Red Planet.

"This is exactly what it looked like in my wildest dreams. But they were pretty wild!" Squyres says.

Squyres guesses the rover might actually be down in a crater.

1009 GMT (5:09 a.m. EST)
Here is another view from Opportunity showing large markings on the surface, possibly from the lander rolling to a stop.

1007 GMT (5:07 a.m. EST)
Controllers have determined the lander base's is fairly level. The pitch is up about five degrees, not unexpected since the lander came to rest on its side and had to right itself to open the petals. There is a 1.8-degree roll to the right.

The heading is about 26 degrees or north-northeast.

1002 GMT (5:02 a.m. EST)
"We done good!" project manager Pete Theisinger reports. "We seem to have a very well-performed vehicle. We didn't have any trouble with the critical deploys."

"I am just speechless," said JPL director Charles Elachi. "A friend of mine told me 'good things happen slowly but great things happen suddenly.' Today, I know exactly what he meant."

0950 GMT (4:50 a.m. EST)
Another news conference is coming up -- in 10 minutes -- so officials can provide status on the rover following the Odyssey data relay session that just occurred.

0945 GMT (4:45 a.m. EST)
Here is the initial panorama showing the landing site.

0940 GMT (4:40 a.m. EST)
An amazing 77 images have been taken by Opportunity and received on Earth. You can view them all here.

0930 GMT (4:30 a.m. EST)
This is a close-up view of the surface from Opportunity's landing site.

As the images were coming to Earth, rover scientist Steve Squyres said, "I will attempt no science analysis because it looks like nothing I've ever seen before in my life."

0927 GMT (4:27 a.m. EST)
"We have another rover on Mars it would appear," Lewicki jokes as images continue to be displayed in Mission Control, prompting more cheers.

0925 GMT (4:25 a.m. EST)
Here is a view from Opportunity showing tiled-like features near the lander.

0923 GMT (4:23 a.m. EST)
Rover lead scientist Steve Squyres says the Meridiani landing site looks like nothing he's ever seen before. There are strange, different features across the area immediately next to the lander.

"I've got no words for this!" he says.

0918 GMT (4:18 a.m. EST)
Opportunity's images show a wildly amazing landscape -- vastly different from the previous Spirit, Pathfinder or Viking landing site.

0917 GMT (4:17 a.m. EST)
"Welcome to Meridiani! I hope you enjoy your stay!" flight director Chris Lewicki proudly says.

0916 GMT (4:16 a.m. EST)
The forward driveway off the lander shows a clear path for the rover, unlike Spirit which had a puffed up airbag blocking that route.

0915 GMT (4:15 a.m. EST)
Images are now flooding in from various rover cameras showing Meridiani Planum -- a place never seen before from the surface.

0914 GMT (4:14 a.m. EST)
The initial images received were taken by rear-facing hazard avoidance cameras on Opportunity.

0912 GMT (4:12 a.m. EST)
The first images of Opportunity have arrived on planet Earth!

0911 GMT (4:11 a.m. EST)
Telemetry shows good current from the power-generating solar arrays, confirming the panels are deployed!

0909 GMT (4:09 a.m. EST)
Data is now flowing into the control room.

0905 GMT (4:05 a.m. EST)
The control room is jam-packed with engineers, scientists and managers, all awaiting to hear Opportunity's status.

"You are privileged to be in one of the most exciting rooms on Earth at the moment," says flight director Chris Lewicki.

If all goes well, this data to be received will begin with engineering health information about the rover and be followed by images from various cameras on Opportunity.

0859 GMT (3:59 a.m. EST)
About 20 megabits of data is being relayed via Odyssey.

0857 GMT (3:57 a.m. EST)
Mission Control is celebrating after the acquisition of data from Opportunity via Mars Odyssey orbiter.

"Cheer!" flight director Chris Lewicki jokingly instructed his team.

The fact that telemetry has been received indicates that the rover has performed its critical deployment activities following landing. Opportunity's exact status has yet to be confirmed, however. That is still to come.

0856 GMT (3:56 a.m. EST)
"We eagerly await the telemetry," flight director Chris Lewicki says from Mission Control.

0845 GMT (3:45 a.m. EST)
The Mars Odyssey spacecraft is currently flying over the Meridiani Planum landing site. It will serve as a relay to transmit data from Opportunity to Earth, if the rover is beaming up telemetry. Mission Control expects to receive information around 4 a.m. EST.

"Earthset" has occurred -- meaning that Earth is no longer visible from landing site for tonight.

0745 GMT (2:45 a.m. EST)
With California Gov. Arnold Schwarzenegger and former Vice President Al Gore looking on, NASA's Opportunity lander slammed into the martian atmosphere and bounced to an airbag-cushioned touchdown early Sunday, joining the crippled-but-recovering Spirit rover on the surface of the Red Planet. Read our full story.

0735 GMT (2:35 a.m. EST)
Spirit's landing base was renamed Columbia Memorial Station. Asked by a reporter about a possible name for Opportunity's base, NASA Administrator Sean O'Keefe would only say "stay tuned" for an announcement.

0717 GMT (2:17 a.m. EST)
The airbag retraction and petal opening should have happened by now. However, officials cannot yet confirm those critical events have occurred.

The Mars Odyssey orbiter will fly over the landing site in about 90 minutes to relay data back to Earth.

0714 GMT (2:14 a.m. EST)
Engineers predict that as the lander base rights itself -- it came to rest on its side -- and opens up, the rover will be pointed to the east.

0706 GMT (2:06 a.m. EST)
Initial indications are Opportunity landed about 24 kilometers from the target.

0700 GMT (2:00 a.m. EST)
"We resurrected one rover, and we saw the birth of another today," says Ed Weiler, NASA associate administrator for space science, speaking of Spirit's problem and the successful landing of Opportunity.

0657 GMT (1:57 a.m. EST)
"We are two-for-two!" Mars Exploration Rover project manager Pete Theisinger just said, prompting a loud round of applause.

The U.S. now has logged five successful landings on Mars out of six attempts -- Opportunity, Spirit, Pathfinder and two Vikings. The only failure was Mars Polar Lander.

0649 GMT (1:49 a.m. EST)
Champagne is flowing as NASA Administrator Sean O'Keefe pours a glass of bubbly for the project officials at the post-landing news conference.

"What a night! I mean, as the old saying goes 'it's far better to be lucky than good.' But you know the harder we work, the luckier we seem to get," O'Keefe said.

"This team is absolutely phenomenal. The very idea that no one dared dream that we could pull off batting a thousand on this. Yet this is a tremendous testimonial of how NASA can really focus on the objective and put every ounce of effort, energy, emotion and talent to an important task. This is just a truly remarkable achievement. This team is the best in the world, no doubt about it!"

0637 GMT (1:37 a.m. EST)
With screams and shouts, the victorious rover team has paraded its way into the briefing room at the Jet Propulsion Laboratory, receiving high-fives and applause.

Both Mars Exploration Rovers -- Spirit and Opportunity -- have safely reached the Red Planet just three weeks apart. The two rovers are located half a world away from each other, having traveled 300 million miles from Earth to Mars.

Although Spirit developed a problem more than two weeks into its mission, engineers remain hopeful it can resume exploring Gusev Crater.

The Opportunity post-landing news conference will begin shortly.

0545 GMT (12:45 a.m. EST)
NASA officials will be holding a post-landing press conference at 1:30 a.m. EST. We will take a brief pause in our live updates.

0535 GMT (12:35 a.m. EST)
Engineers confirm that the spacecraft is resting on its side. But the lander is designed to right itself during the petal opening sequence.

Also, they believe that Opportunity wasn't really rolling all of that time. The fluctuating indication interpreted as rolling was actually an artifact of the communications path with the craft on its side and not the vehicle still in motion.

0532 GMT (12:32 a.m. EST)
Preliminary data shows the initial impact was two-or-three g's, a JPL spokesperson says.

0528 GMT (12:28 a.m. EST)
With Opportunity resting on the surface of Mars at Meridiani Planum, it will use motors to retract the impact-cushioning airbags. The lander then will open up like a flower, lowering its petals to reveal the rover tucked inside.

Next, the rover will deploy its power-generating solar panels. Then the Pancam Mast Assembly will be raised up. It can begin taking some pictures of the landing site once those events are completed. The initial images, if snapped this morning, would be relayed to Earth via the Mars Odyssey orbiter overnight.

0526 GMT (12:26 a.m. EST)
The Mars Global Surveyor orbiter collected data from Opportunity during the entry, descent and landing sequence. That information is transmitted to Earth for engineers to analyze.

0525 GMT (12:25 a.m. EST)
A strong signal is still being received from Opportunity -- now 20 minutes since touchdown.

0524 GMT (12:24 a.m. EST)
Controllers still see a fluctuation in the data that would indicate the vehicle is still rolling. However, engineers suspect that may not be true.

0523 GMT (12:23 a.m. EST)
Initial indication is being received that the rover has landed on the +Y petal down.

0522 GMT (12:22 a.m. EST)
Opportunity is telling controllers that no faults or errors were experienced during the rollout.

0519 GMT (12:19 a.m. EST)
Mission Control still seeing a very slow motion from the rover.

0517 GMT (12:17 a.m. EST)
Opportunity is still moving!

0516 GMT (12:16 a.m. EST)
The roll continues -- more than 10 minutes after the impact.

0514 GMT (12:14 a.m. EST)
Mission Control is still receiving evidence that Opportunity is slowly rolling, which is expected.

0512 GMT (12:12 a.m. EST)
Also in Mission Control is Arnold Schwarzenegger, California's governor. He and Gore are talking to the entry team and looking at data screens just moments after touchdown.

0511 GMT (12:11 a.m. EST)
Signals from Opportunity now show that the spacecraft is rolling. Following the initial impact, the airbag shrouded spacecraft bounces and rolls for several minutes before coming to a rest.

0510 GMT (12:11 a.m. EST)
Former Vice President Al Gore is in Mission Control.

0508 GMT (12:08 a.m. EST)
Complete joy and relief in Mission Control as Opportunity has landed at Meridiani Planum.

0508 GMT (12:08 a.m. EST)
A good signal is still being received! Unlike the Spirit landing where signal was lost immediately after touchdown, Opportunity continues to talk to Earth.

0506 GMT (12:06 a.m. EST)
After a short loss of signal from the rover, a strong signal is now being received as Opportunity arrives on Mars!

0505 GMT (12:05 a.m. EST)
BOUNCING ON MARS! Mission Control has received a signal of Opportunity bouncing on the surface of Mars.

0505 GMT (12:05 a.m. EST)
The braking rockets have been ignited! Touchdown will occur any moment.

0505 GMT (12:05 a.m. EST)
The radar is measuring the approaching surface. Standing by for retro rocket ignition.

0504 GMT (12:04 a.m. EST)
The heat shield has been jettisoned! This exposes the lander inside the descent module.

0504 GMT (12:04 a.m. EST)
Chute is out! Mission Control has received indication of deployment of Opportunity's supersonic parachute.

0503 GMT (12:03 a.m. EST)
Deceleration has eased to less than 1 g. Standing by for chute deployment at a speed of about 1,000 mph.

0502 GMT (12:02 a.m. EST)
Altitude 12 miles, some 27 miles uprange from the landing site. Deceleration continues as the spacecraft plunges through the atmosphere.

0502 GMT (12:02 a.m. EST)
Maximum deceleration has been reached between 6 and 7 g's.

0501 GMT (12:01 a.m. EST)
The Opportunity lander is now transmitting a tone that tells Mission Control is it decelerating at several g's.

0500 GMT (12:00 a.m. EST)
The navigation team in Mission Control reports they detect entry into the atmosphere.

0500 GMT (12:00 a.m. EST)
Opportunity is 73 miles above the planet, traveling at 12,187 miles per hour, 441 miles uprange from the landing site.

0459 GMT (11:59 p.m. EST Sat.)
ENTRY INTERFACE. Opportunity's "six minutes of terror" has begun as it makes a fiery descent into the Martian atmosphere, slowing from 12,000 miles per hour to zero in the next six minutes.

0459 GMT (11:59 p.m. EST Sat.)
The spacecraft is about 600 miles uprange from its landing site.

0458 GMT (11:58 p.m. EST Sat.)
Opportunity is 128 miles above Mars.

0457 GMT (11:57 p.m. EST Sat.)
Two minutes from hitting the top of the atmosphere.

0455 GMT (11:55 p.m. EST Sat.)
Opportunity is 382 miles above the planet, traveling at 11,592 miles per hour. Time to touchdown is 10 minutes.

0455 GMT (11:55 p.m. EST Sat.)
The landing site weather forecast calls for a temperature of -15 degrees C and 8 knots of crosswind from the east with gusts to 30 knots.

0454 GMT (11:54 p.m. EST Sat.)
Five minutes from entering the atmosphere. Opportunity is now traveling at 11,400 mph, continuing to increase due to the pull of Martian gravity.

0453 GMT (11:53 p.m. EST Sat.)
Opportunity is cocooned with its descent module called the aeroshell. The aeroshell which has two parts -- a heat shield that faces forward and a backshell.

Here is an overview:

The system for getting each rover safely through Mars' atmosphere and onto the surface relies on an aeroshell, a parachute and airbags. The aeroshell has two parts: a heat shield that faces forward and a backshell. Both are based on designs used successfully by NASA's Viking Mars landers in 1976 and Mars Pathfinder in 1997.

The parachute is attached to the backshell and opens to about 15 meters (49 feet) in diameter. The parachute design was tested under simulated martian conditions in a large wind tunnel at NASA's Ames Research Center near Sunnyvale, Calif.

The backshell carries a deceleration meter used to determine the right moment for deploying the parachute. Solid-fuel rockets mounted on the underside of the shell reduce vertical velocity and any excessive horizontal velocity just before landing.

The airbags, based on Pathfinder's design, cushion the impact of the lander on the surface. Each of the four faces of the folded-up lander is equipped with an envelope of six airbags stitched together. Explosive gas generators rapidly inflate the airbags to a pressure of about 6900 Pascal (one pound per square inch). Each airbag has double bladders to support impact pressure and, to protect the bladders from sharp rocks, six layers of a special cloth woven from polymer fiber that is five times stronger than steel. The fiber material, Vectran, is used in the strings of archery bows and tennis racquets.

0451 GMT (11:51 p.m. EST Sat.)
A pre-entry poll of Mission Control is underway.

0449 GMT (11:49 p.m. EST Sat.)
A low-gain antenna on the spacecraft's backshell is transmitting simple "tones" to give Earth some idea of its health during entry.

The system has about 100 possible tones to provide information such as whether the cruise stage has separated, whether the parachute opens and whether the deceleration rate is within the expected range.

0448 GMT (11:48 p.m. EST Sat.)
After a brief loss of signal during cruise stage separation, the Deep Space Network has again locked on to Opportunity.

0447 GMT (11:47 p.m. EST Sat.)
Opportunity is 1,264 miles above the planet, traveling at 10,329 miles per hour. Time to touchdown is 18 minutes.

0445 GMT (11:45 p.m. EST Sat.)
The cruise stage has been jettisoned from the Opportunity descent module! The stage, which separates with the help of springs, will ultimately impact Mars.

Opportunity is poised for entering the atmosphere in about 13 minutes.

0444 GMT (11:44 p.m. EST Sat.)
A calibration tone has been received in Mission Control. This confirms the system that will be used to send a signal from the rover to Earth during descent.

0443 GMT (11:43 p.m. EST Sat.)
The pointing error now is just 0.793 degrees. The margin of error can be up to 10 degrees.

0441 GMT (11:41 p.m. EST Sat.)
Data from the coolant lines shows that all of the freon has been vented. The spacecraft should now be completing its attitude adjustment to counteract the small wobble caused by the venting.

0440 GMT (11:40 p.m. EST Sat.)
The power system controllers report the current draw from the lander batteries is normal. Earlier, there had been some worry about the power but that was caused by telemetry drop out. All appears fine.

Opportunity is currently 2,183 miles from Mars, traveling over 9,400 miles per hour.

0435 GMT (11:35 p.m. EST Sat.)
Landing is now 30 minutes away.

The next major event will be separation between the no-longer-needed cruise stage from the descent module containing the Opportunity rover. This jettison is scheduled for 11:44 p.m. EST.

Here is NASA's description of the cruise stage:

The cruise stage provides capabilities needed during the seven-month passage to Mars but not later in the mission, such as a propulsion system for trajectory correction maneuvers. Approximately 2.6 meters (8.5 feet) in diameter and 1.6 meters (5.2 feet) tall, the disc-shaped cruise stage is outfitted with solar panels and antennas on one face, and with fuel tanks and the aeroshell on the other. Around the rim sit thrusters, a star scanner and a Sun sensor.

The propulsion system uses hydrazine propellant stored in two titanium tanks. Since the the entire spacecraft spins at about 2 rotations per minute, fuel in the tanks is pushed outward toward outlets and through fuel lines to two clusters of thrusters. Each cluster has four thrusters pointing in different directions.

The star scanner and Sun sensor help the spacecraft determine its orientation. Since the rover's solar arrays are tucked away inside the aeroshell for the trip, the cruise stage needs its own for electrical energy. The arrays could generate more than 600 watts when the spacecraft was about as far from the Sun as Earth is, and generate about half that much as it nears Mars.

The cruise stage also carries a system for carrying excess heat away from the rover's computer with a pumped freon loop and rim-mounted radiators.

0431 GMT (11:31 p.m. EST Sat.)
Opportunity is currently 3,334 miles from Mars, traveling at 8,817 miles per hour.

Mission Control confirms that the gas generator heaters are active.

0426 GMT (11:26 p.m. EST Sat.)
Meanwhile, the Mars Global Surveyor and Mars Odyssey orbiters are verified in good shape. The spacecraft will be used for communications relay from Opportunity over the course of the evening. MGS will be receiving live information from the rover during descent while Odyssey will fly over the landing site a few hours later to collect data for transmission back to Earth.

0424 GMT (11:24 p.m. EST Sat.)
The venting appears to be complete.

0420 GMT (11:20 p.m. EST Sat.)
The spacecraft is now scheduled to begin a procedure to vent freon coolant from its Heat Rejection System. The freon was used to cool systems during the cruise to Mars and is no longer needed.

This venting will cause the spacecraft to wobble a bit, so tiny thrusters will be used to keep the lander on course for entry.

0418 GMT (11:18 p.m. EST Sat.)
Flight director Jason Willis has polled his Mission Control team. Everything continues to look good for Opportunity's landing at 12:05 a.m. EST.

Jettison of the cruise stage is upcoming at 11:44 p.m. and entry into the atmosphere begins at 11:59 p.m.

0415 GMT (11:15 p.m. EST Sat.)
The spacecraft is 5,522 miles above Mars, traveling at a velocity of 8,094 miles per hour.

0414 GMT (11:14 p.m. EST Sat.)
Heaters are being activated to condition solid rockets used by gas generators aboard the lander. The generators inflate the impact-cushioning airbags moments before touchdown.

0412 GMT (11:12 p.m. EST Sat.)
The turn to entry attitude has been verified complete. The pointing error is 0.37 degrees, which is well within margin.

This turn was a critical event prior to Opportunity making the fiery plunge into the atmosphere by reorienting to put the heat shield facing the planet. Had the turn not occurred, the craft would burn up during entry.

0405 GMT (11:05 p.m. EST Sat.)
Landing of Opportunity in the Meridiani Planum region of Mars is now just one hour away!

Meridiani Planum is considered one of the smoothest, flattest places on the Red Planet.

0400 GMT (11:00 p.m. EST Sat.)
Opportunity's onboard software is running the show tonight. The entry, descent and landing activities are controlled entirely by the rover spacecraft. Ground controllers on Earth are simply spectators.

0354 GMT (10:54 p.m. EST Sat.)
Opportunity is currently 8,268 miles from Mars, traveling at 7,758 miles per hour. The craft's speed will continue to increase as the Martian gravity pulls Opportunity to the planet.

0345 GMT (10:45 p.m. EST Sat.)
The rover's turn appears to be largely complete at this time, Mission Control reports.

0337 GMT (10:37 p.m. EST Sat.)
Opportunity is currently 10,880 miles from Mars, traveling at 7,683 miles per hour.

0336 GMT (10:36 p.m. EST Sat.)
The turn to entry attitude is underway. This rotation will orient the spacecraft such that the heat shield is facing the atmosphere. Prior to this time, Opportunity was flying with its cruise stage solar panels pointed at the Sun and communications antenna in line with Earth.

0335 GMT (10:35 p.m. EST Sat.)
Opportunity's landing is now 90 minutes away as NASA attempts to put its second Mars Exploration Rover on the surface of the Red Planet.

Although Spirit's landing was completely successful, giving confidence that tonight's descent of Opportunity will have a positive outcome, project manager Pete Theisinger cautions that nothing is assured when traveling to another planet with complex machines.

"I think you need to understand what the Spirit has proven and what is has not proven. The design of the two vehicles are identical but they are separate vehicles. So the Spirit has proven the design -- this entry, descent and landing system can work. But it has not established the integrity of Opportunity," Theisinger says.

0325 GMT (10:25 p.m. EST Sat.)
An assessment poll of flight controllers has been performed in advance of Opportunity making its turn to the atmospheric-entry orientation. No significant issues were reported with the spacecraft, the Deep Space Network tracking system or Mars Global Surveyor orbiter that will be used to receive data from Opportunity during landing.

The turn is expected to begin at 10:34 p.m. EST.

0316 GMT (10:16 p.m. EST Sat.)
The Opportunity rover spacecraft has completed the switch from its medium-gain communications antenna to the low-gain antenna. This transmission means the rover is now sending communications at a rate of just 10 bits per second.

0305 GMT (10:05 p.m. EST Sat.)
NASA has invested over $800 million in the Spirit and Opportunity rover missions. In addition, the space agency has the Mars Global Surveyor and Mars Odyssey spacecraft orbiting the planet today and several additional probes in the works.

But why explore Mars?

"The simple answer is we are going to Mars to search for life," Ed Weiler, NASA's space science chief says.

"We are going there not just to understand a science question but a basic human question that has been around since we started walking out of the caves finally and looking up into the sky -- are we alone?

"That's why we are going to Mars, that's why eventually we will send humans to Mars -- to not plant flags and put their footprints on and hit a few golf balls. We are going there to send human biologists to help us in that search for life."

The battle cry of NASA's Mars exploration program is "follow the water." The Spirit and Opportunity rovers are specifically looking for evidence of past water on the Red Planet.

"We are following the water because on Earth we find out that where ever you find water, organic material and energy you find life. So the key for the search on Mars is following the water. That will lead us if there was past life or if there is present life," Weiler says.

0235 GMT (9:35 p.m. EST Sat.)
As Opportunity's landing nears and engineers continue to examine Spirit's trouble, here are some words from NASA's space science chief Ed Weiler:

"I appreciate that by now you realize that landing on Mars is really tough and operating on Mars is even tougher, as we found out. We warned you of that three weeks ago (at Spirit's landing).

"Some of you and probably some of us have gotten used to success after success after success. But as we've have seen, exploration is a roller coaster. We've had the early ups and now we've had a down. It seems like we're back going up again. However, I can absolutely guarantee you there will be more downs and there will be more ups with both Opportunity and Spirit.

"However, what the last few days has proven to me is that we have got the absolute best team on Earth operating these (rovers)."

Traveling from NASA Headquarters in Washington to the Jet Propulsion Laboratory for tonight's landing, Weiler thought he'd find a dark mood at JPL mission control given the ailing Spirit.

"I came here expecting to be literally at a funeral. I arrived here yesterday at 3 o'clock and things were looking pretty grim. But already last night things were looking a little bit better and then things got a lot better early this morning. There is a lesson in that."

This morning controllers were able to narrow the search for Spirit's ailment, giving officials renewed hope that the rover can resume its exploration of Gusev Crater in a couple of weeks.

0205 GMT (9:05 p.m. EST Sat.)
The landing of Opportunity is now three hours away.

In about 90 minutes, the spacecraft performs a turn to position its heat shield facing the atmosphere. This will not only prepare for entry but also the jettison of the no-longer-needed cruise stage. Separation between the cruise stage and the descent module is expected around 11:44 p.m. EST.

0035 GMT (7:35 p.m. EST Sat.)
The in-coming Opportunity rover is getting ever closer to Mars. Time to touchdown is now just four-and-a-half hours away.

Before the fiery entry into the Martian atmosphere can occur, the ring-shaped cruise stage must be jettisoned from the descent module containing the Opportunity rover. This is scheduled for 11:44:46 p.m. EST.

Entry interface occurs at 11:59:46 p.m. EST as the spacecraft punches into the upper fringes of the atmosphere about 128 kilometers above the planet's surface while traveling 5.4 kilometers per second (12,000 miles per hour). The protective heat shield is designed to withstand the 2,600-degree F temperature expected from the friction of falling through the atmosphere. Peak heating will happen around 12:01:28 a.m. at an altitude of 42.6 kilometers.

With about two minutes left in the descent, at 12:03:49 a.m. and 8.9 kilometers above the ground, the craft's parachute will be deployed.

Based upon the reconstruction of data gathered during Spirit's descent and weather reports about the atmosphere above Meridiani Planum, engineers have decided to have Opportunity open its parachute slightly earlier than Spirit did.

At 12:04:19 a.m. and an altitude of 5.8 kilometers, the bottom half of the aeroshell descent module is jettisoned, exposing the lander. The top half of the shell, still riding the parachute, will lower the lander on a small tether.

Activation of the radar altimeter occurs at 5.4 kilometers above the surface at 12:04:24 a.m. The descent imaging camera system initiates at 12:05:07 a.m. at an altitude of two kilometers.

The impact-cushioning airbags surrounding the lander will inflate at 12:05:31 a.m., followed a half-second later by ignition of retro rockets on the upper shell to bring the descent speed to zero. The tether will be cut about 12 meters above the surface at 12:05:34 a.m.

The first moment of touchdown -- starting a series of bounces -- is targeted for 12:05:37 a.m. EST (0505:37 GMT).

The spacecraft is expected to bounce and roll for several minutes before coming to rest.

Mission Control hopes to receive communication "tones" from the rover throughout the entry, descent and landing.

We will be posting updates on this page all evening!

SATURDAY, JANUARY 24, 2004

With NASA's Opportunity rover on track for an early Sunday "bouncedown" on Mars, engineers said today they have identified the problem crippling the Spirit rover and hope to resume relatively normal science operations in three weeks or so. Read full story.

2345 GMT (6:45 p.m. EST)

Louis D'Amario, the Mars Exploration Rover navigation team chief, says Opportunity remains on course for arrival on the plains of Meridiani tonight at about 12:05 a.m. EST (Earth Receive Time) after a seven-month, 280-million voyage.

The cigar-shaped landing zone is 46 miles long and 4 miles wide, which is 0.001 percent of the martian surface, he said.

To guide Opportunity to its landing site, controllers had the chance to perform five Trajectory Correction Maneuvers, plus one contingency burn. But just three were needed.

"We managed to target Opportunity to the desired atmospheric entry point, which will bring us to the desired landing point, using only three Trajectory Correction Maneuvers in that 280 million mile trip from Earth to Mars.

"If you remember back to the Spirit (pre-landing) press conference, I used the analogy to playing a very long hole in golf. For Spirit, only used four shots -- four Trajectory Correction Maneuvers -- so we got a birdie. But for Opportunity we only used three, so we got an eagle. We did even better!"

2150 GMT (4:50 p.m. EST)

Rover project manager Peter Theisinger gave the following update on activities to diagnose Spirit's ailment and return the craft to working order:

"We made good progress overnight and the rover has been upgraded from critical to serious. We have a working hypothesis we are pursuing that is consistent with many of the observables and consistent with operations that we performed on the vehicle last night. It involves the flash memory on the vehicle and the software used to communicate with that memory.

"The processor on Spirit has three kinds of memory:

"There is the random access memory just like the memory in your computer, which is used basically in a real-time mode. And that memory is volatile, so when we turn off the rover at night that memory goes away.

"We have flash memory. That memory is just like the memory in a digital camera. It can also be read to and written from easily. But it has non-volatile characteristics -- the information that is stored there stays overnight even if the vehicle is powered down.

"And then we have we call double EPROM, which is electrically-programmable memory. That is more difficult to write to and read from, and we use that to store part of the flight software image.

"The vehicle normally uses the flash memory mostly for the storage and retrieval of engineering and the scientific telemetry. The software has to communicate with the flash memory -- has to open up files, establish file directories, close files in that flash memory. That process has to work correctly.

"We are capable of operating the vehicle without going to the flash memory in what we call a 'cripple mode.' That is name we have chosen -- you should not read too much into that. That basically tells the flight software that when it boots up, it should operate with its file directory out of the random access memory rather than the flash memory. That would avoid any issues that we might have with either the flash memory itself or the flight software that is used to write to it.

"Let me talk about the chronology of what happened in the last 24 hours. If you recall when we last talked at yesterday's press conference, we were attempting to shut down the vehicle because the batteries were becoming depleted. We had an apparent inability to shut down the vehicle last night, yesterday at the end of the Mars day, which is about the time of the press conference at 9 a.m. Pacific. That was in fact confirmed because later we had a UHF communications session with Odyssey where we got 73 megabits of data, mostly fill or garbage data, although we did get some fault data, some current, some 14 hours old.

"We did not know but thought we might go into low-power overnight if the batteries were fully depleted. When came up this morning we looked for the 9:30 Mars time communications window and it was not there, indicating, we thought, that we had gone into low-power. That would cause the vehicle to come up at 11 o'clock and tell us that.

"We, just prior to 11 o'clock, sent a command to the vehicle that said 'go into this cripple mode.' That is only done at the next reset, so then we sent a command to the vehicle that said 'and reset' in order to do that. And we timed it so that when the 11 o'clock session would start, we would begin to get that session at 10 bits per second indicating we'd gone into low-power. When the commands reached the spacecraft light-time away, it would send us into cripple mode, reset the computer and we would come up in the mode. And in fact that is precisely what happened.

"At that point, we commanded a one-hour communications session at 120 bits per second. That communications session happened as planned.

"The progressive set of resets that we were getting into every hour did not reoccur, leading us to conclude that our hypothesis is largely correct -- that is there is something involved in the flight software that talks to the flash memory that's causing this difficulty.

"Why that might cause us difficulty is because when the spacecraft first wakes up it needs to communicate with the flash memory to establish a file structure and when it goes to sleep and shuts down, just like you shut down your computer at home, it needs to go out to that memory and close all of those files and clean everything up. If it is unable to do that, it would not complete those tasks appropriately and will basically reset itself and not shut down.

"In the midst of that 120 bits per second, one-hour session, we decided to shut down the vehicle in order to replenish the batteries. We commanded the shutdown just prior to the end of the communications session so that we would see the communications session terminate early if we were able to operate it correctly. That happened. And we sent two post-shutdown beeps, which we expect not to hear if it is asleep but we would hear if it was not asleep, and we did not get those, once again confirming that the vehicle to the best of our ability to determine is now sleeping on Mars.

"We also yesterday as part of the command sessions during this period of time terminated tonight's UHF passes and reset the uploss timer. The uploss timer is a set of fault code that go into play when the vehicle thinks it has a communications problem and causes some things to switch state and we didn't want to get into that if we could avoid it. Both of those were confirmed to be successful.

"So we have a vehicle that is stable now in power and thermal. We have a working hypothesis that we have confirmed. The fault protection to the best of our estimation has worked as designed. It took us a lot to figure out what was going on, but we think everything has worked in the fault protection as we expected it to do.

"We have a go-forward plan. The cripple mode, which we can use every day, needs to be re-established every day because it loses the memory that that's the way it should start up. So every morning we will need to start up in cripple mode, so we need to establish an operational way of doing that every day for the next few sols (Mars days).

"We need to establish a high-rate link in order to be able to get much more data back, particularly if we want to read out the flash memory and determine what has happened. What we will plan to do is likely to use the Odyssey afternoon relay pass for that purpose prior to the afternoon shutdown.

"We need to then establish the contents of flash to find out what happened and then we need to move forward with the diagnosis and recovery of the vehicle capability based upon what we find there.

"Remember that this was all kicked off by Sequence 2502. That was the sequence that was using the elevation motor in the mast failing out, failing to complete (on Wednesday). We still do not know the details of why that happened and we need to do that.

"The mission consequences of this are uncertain at the present time. But I think that we feel that we probably have more capability left in the vehicle that we can establish than the worst-case scenarios by quite a bit. We still see a couple of weeks to determine what had happened and to rebuild our confidence into what is working on the vehicle and to get back closer to routine operations. I think we are probably like three weeks away from driving, I am guessing.

"The team will begin to go into double-shift operations probably a day or so after Opportunity's landing where we have a re-plan period and then an operational period as we begin to work through the forensics of this.

"But this is a very good news. We've established an ability to communicate with the vehicle reliably, we've established that in fact we do have controllability of the vehicle, can establish a good power and thermal state, our working hypothesis is one that we can work around with significant measure if it turns out our working hypothesis is correct. So a good day for an Opportunity landing."

2011 GMT (3:11 p.m. EST)

Meanwhile, the Opportunity rover is nine hours away from touchdown at Meridiani Planum.

"We are in great shape," Opportunity mission manager Jim Erickson says. The vehicle is properly oriented with its solar panels facing the Sun and communications antenna package in view of Earth.

The chance to do a last-minute trajectory correction maneuver today has been cancelled. The spacecraft is on the proper track with no need for adjustment, officials report.

2003 GMT (3:03 p.m. EST)

Pete Theisinger, Mars Exploration Rover project manager, says the team has made good progress overnight with Spirit. The rover's status has been upgraded from "critical" to "serious" condition.

Engineers are working on a theory that there is a problem between the flight software and the rover's flash memory.

We'll post Theisinger's briefing as soon as possible.

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

Mars rover project officials will be holding a 3 p.m. EST news conference from the Jet Propulsion Laboratory to provide an update on activities with Spirit and the latest on Opportunity's trek to landing tonight.

We will update this page as information develops.

0400 GMT (11:00 p.m. EST Fri.)

While efforts to revive the Spirit rover continue, the sister-craft Opportunity remains on course for its Saturday night/Sunday morning landing on the Red Planet.

Opportunity's touchdown at Meridiani Planum -- a smooth, flat plain near the equator halfway around the planet from Spirit's Gusev Crater landing site -- is scheduled for 12:05 a.m. EST (0505 GMT).

The landing site for Opportunity was selected because scientists believe there is an Oklahoma-sized area of gray hematite, a mineral that usually forms in the presence of water.

"Gray hematite is a mineral indicator of past water. It is not always associated with water, but it often is," said Joy Crisp, project scientist for the Mars Exploration Rover project.

The rover will search for the material to determine if the hematite layer comes from sediments of an ancient ocean, from volcanic deposits altered by hot water, or from other environmental conditions in the planet's distant past.

"Hematite forms in a number of different ways on Earth but most of them involve the action of liquid water," added Steve Squyres, the rovers' principal investigator. "So you can think of the hematite mineral signatures being kind of a beacon that's saying to us, 'hey, water may have been here.' Now we don't know how it formed, it could have been a hydrothermal system, could have been a lake, we're not sure. But it says, mineralogically, water."

Opportunity carries the same set of science tools as Spirit -- multiple cameras, a rock-grinding device and sophisticated instruments to determine the composition of soil and rock samples.

"We want to know if the grains of hematite appear to be rounded and cemented together by the action of liquid water or if they're crystals that grew from a volcanic melt. Is the hematite in layers, which would suggest that it was laid down by water, or in veins in the rock, which would be more characteristic of water having flowed through the rocks," Crisp wonders.

NASA's orbiting Mars Global Surveyor discovered a couple of years ago that Meridiani Planum featured gray hematite, prompting researchers to send a rover to the locale.

"The area where we are going has 10 to 15 percent gray hematite. What are the other materials found with the hematite? Clays and carbonates would indicate there had been water in the area. If the area had been volcanic, you would expect to see other types of minerals like olivine and pyroxene," Crisp says.

"We're very interested to know if this region could have been like Yellowstone, with hot springs, so we'll be looking to see if there are other minerals in the area such as those at Yellowstone."

The battle cry of NASA's Mars exploration program is "follow the water." Proving that Mars once had liquid water would help to determine if the planet could have supported life long ago.

"Knowing just how the hematite on Mars was formed will help us characterize the past environment and determine whether that environment was favorable for life. One big question, of course, is whether life ever started on Mars. This mission probably won't tell us that, but it may well lead to future mission that can answer that question."

We will provide live updates on this page throughout the landing!

0330 GMT (10:30 p.m. EST Fri.)

Despite two commands from engineers on Earth to enter sleep mode to conserve power, Spirit remained awake all day Friday, Mission Control reported late tonight.

"Shortly before (3 p.m. EST), controllers were surprised to receive a relay of data from Spirit via the Mars Odyssey orbiter. Spirit sent 73 megabits at a rate of 128 kilobits per second. The transmission included power subsystem engineering data, no science data, and several frames of 'fill data.' Fill data are sets of intentionally random numbers that do not provide information," NASA officials said.

"Spirit had not communicated successfully through Odyssey since the rover's communications difficulties began on Wednesday."

FRIDAY, JANUARY 23, 2004
2055 GMT (3:55 p.m. EST)

The crippled Spirit rover remains in critical condition on the surface of Mars, engineers said today, the victim of ongoing electronic seizures that have caused its central computer to reboot itself more than 60 times over the past two days.

Engineers successfully coaxed the rover to beam back limited engineering data during two brief communications sessions and they were relieved to discover the spacecraft's power system was providing the necessary life support. But Spirit's state of mind was clearly -- and unusually -- different in both sessions, ruling out any simple explanations for what might have gone wrong.

Read full story.

1945 GMT (2:45 p.m. EST)

Pete Theisinger, manager of the Mars Exploration Rover project, says Spirit is in "critical condition" as it sits at Gusev Crater.

"We do not know to what extent we can restore functionality to the system because we don't know what's broke. We don't know what started this chain of events. I think, personally, that is a sequence of things. And we don't know, therefore, the consequences of that.

"I think it is difficult, at this very preliminary stage, to assume that we did not have some type of hardware event that caused this to start. Therefore, we don't know to what extent we can work around that hardware event and to what extent we can get the software to ignore that hardware event, if that is what we eventually have to do.

"So we have a long way to go here with the patient in 'intensive care.' But we have been able to establish that we can command it, and we have been able to establish that it can give us information, and we have been able to establish that the power system is good and we are thermally OK. Those are all very, very, very important pieces of information and state.

"We are a long, long, long way from being done here. But we do have serious problems and our ability to eventually work around them is unknown.

"I'm trying to tell you do not to expect a big sea change in either knowledge or theory in the next several days because this is a very complex problem and we have very limited visibility."

1930 GMT (2:30 p.m. EST)

During the question-and-answer portion of today's briefing, project manager Pete Theisinger gave this summary:

"The software is in X-band fault mode. We surmise it got there because of some problem with the high-gain antenna pointing, and that is why the second high-gain antenna pass on Wednesday did not work. It gives us a little bit of a tale-tell for what is going on with the processor now.

"But as I pointed out to you, the flight software is not functioning normally. The two times we have gone and communicated with the system, we have gotten different flight software behaviors. Therefore we do not have assurance the next time we go and ask for it we will get either one of those two behaviors or perhaps a third behavior.

"We are trying to look at those responses to determine 'ok, how come it's behaving that way? And how come when we boot up it doesn't get better?' Those are the kinds of questions we are raising at the moment.

"We have quite a bit of information but clearly not as much as you would like."

We will have a complete story wrapping up the news conference as soon as possible.

1905 GMT (2:05 p.m. EST)

While engineers work to understand and fix Spirit's troubles, a team reconstructing the rover's entry, descent and landing has made great progress.

This "path" of Spirit's landing has left "marks" on Mars as seen by the orbiting Mars Global Surveyor and Spirit's Descent Image Motion Estimation System camera. See the image here.

1855 GMT (1:55 p.m. EST)

Here is project manager Pete Theisinger's briefing to reporters from earlier this hour:

"We have been able to command Spirit and we have gotten limited data in return. The flight software is not behaving normally.

"I would like to go into some details of the chronology of events that have happened since I talked to you yesterday.

"When I left here yesterday there was preliminary indication that a request for an acknowledgement sent to the spacecraft at what would have been an emergency or fault command rate was received and acknowledged from the spacecraft -- and that was correct. The spacecraft did see us yesterday.

"We attempted to command the spacecraft to send us telemetry yesterday. We were very late in the day and on top of a UHF command session, and that command did not work for what we believe were those reasons.

"This morning, we sent an early beep to the spacecraft and did not get a response. As we were preparing to send a second, the spacecraft talked to us. We got very fractional frames and then moved very quickly to ask it to speak to us for 30 minutes at 120 bits per second. We got 20 minutes of transmission in that occasion, which was a single frame of engineering data repeated.

"Then we repeated that full sequence of events and we got about 15 minutes of engineering data at 120 bits per second where the frames were updated for 15 minutes and then for the second 15 minutes we had nothing but fill data.

"The spacecraft attempted a short communication window at the end of the day, which ended.

"The spacecraft has been in a processor reset loop of some type, mostly since Wednesday, we believe, where the processor wakes up, loads the flight software, uncovers a condition that would cause it to reset. But the processor doesn't do that immediately. It waits for a period of time -- at the beginning of the day it waits for 15 minutes twice and then for the rest of the day it waits for an hour -- and then it resets and comes back up.

"The indications we have on two occasions is that the thing that causes the reset is not always perceived to be the same. We are confused by that, but that's the facts as we presume them to be right now.

"We know that the sequence which began on Wednesday morning to do some calibration of one of the Mini-TES motors, that sequence did not run to completion. And we know that the spacecraft believes it is now in an X-band fault condition, which can be caused by a large number of things, but one of them could be the inability to move the high-gain antenna.

"If you recall, we did know as of 1 o'clock Mars Time on Wednesday that the spacecraft did not believe itself to be in a fault condition, although it could be having problems. We know that because we tried this beep at 31.25 (bits per second) that day and it worked. That's not a rate we would expect if the spacecraft thought it was a fault condition.

"The team is basically taking the data it had this morning, as collected, and moving forward and analyzing what they know and preparing a plan of action for tomorrow and for the days following. We believe, based upon everything we know right now, that we can sustain the current state of the spacecraft -- from a health standpoint -- for a substantial, perhaps indefinite amount of time. There is no indication that we have an imminent power problem or thermal issue. There's indications that (the spacecraft has) not been going to sleep at night like we expected -- that we have been up for a lot or most of both nights -- and we are looking at what things could cause that to take place.

"An anomaly team has been formed, completely separate from the Opportunity team. They will working a schedule that will look like 0500 Mars Time to about 1500 Mars Time. So they are going to synch up with the Spirit's day. So that means tonight they will be coming in about midnight. The first part of that will be kind of a re-examination of the data, whatever they have been able to collect and analyze in the period of time and kind of a go-forward plan for the day. They will be on consoles for the day and then there will be a post-day, couple-hour meeting of what they know and to work on theories.

"I expect this to go on in this mode for several days of talking to the spacecraft, gathering more data, winnowing out theories, testing those theories against spacecraft observables and continuing that process.

"I think we should expect that we will not be restoring functionality to Spirit for a significant period of time -- I think many days, perhaps a couple of weeks -- even in the best of circumstances, from what we see today.

"Now, we have Opportunity coming in tomorrow night. We have the lander passivation sequence is going to start running tonight. We have made the appropriate personnel and staffing adjustments to make sure we have completely severed the efforts and that we can sustain Opportunity's (entry, descent and landing).

"It is likely, depending upon what happens in the next 48 to 72 hours, that we may not continue the Opportunity impact-to-egress with the same pace and dispatch that we did on Spirit. It depends on if we can get Opportunity to a defined, sustainable state on the ground and we can continue to make progress against Spirit with those assets, we will likely do that and try and continue to make progress on Spirit to get it back to some level of functionality. That's a decision the project will make in consultation with management as we take the temperature of this thing over the next couple of days."

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

At the news conference underway right now, project manager Pete Theisinger says that the data received from Spirit this morning indicates that the rover's flight software is "not behaving normally."

An anomaly team has been formed to continue gathering data from the rover and narrow the possible causes of the situation.

Theisinger says the rover should be able to sustain its health for an indefinite amount of time. He also noted that restoring Spirit to normal operations could take a couple of weeks.

1700 GMT (12:00 p.m. EST)

Teams are still analyzing the information received from the Spirit rover this morning, the Jet Propulsion Laboratory says. A news conference with project officials to provide a status report on recovery operations is scheduled for 1 p.m. EST today.

1512 GMT (10:12 a.m. EST)

Mission Control has received actual data from Mars Exploration Rover Spirit after commanding the craft to transmit the information.

"The spacecraft sent limited data in a proper response to a ground command, and we're planning for commanding further communication sessions later today," said project manager Pete Theisinger.

Officials have not yet said what the data indicated or other details.

The data was received in a communication session that began at 8:26 a.m. EST (1326 GMT) and lasted 20 minutes at a data rate of 120 bits per second.

JPL says it sent the command to the rover at 8:02 a.m. EST (1302 GMT) via the Deep Space Network complex in Spain telling Spirit to begin transmitting.

Spirit stopped sending scientific and engineering health data on Wednesday, then missed several scheduled communications sessions. A heart beat "beep" was received yesterday confirming at Spirit could hear Earth and responded with the simple tone. A signal was also detected earlier this morning, prior to the retrieval of data.

1449 GMT (9:49 a.m. EST)

NASA's Deep Space Network communications station near Madrid, Spain, received a signal from the Spirit rover at 7:34 a.m. EST (1234 GMT) today, officials report.

"The transmissions came during a communication window about 90 minutes after Spirit woke up for the morning on Mars. The signal lasted for 10 minutes at a data rate of 10 bits per second," the Jet Propulsion Laboratory announced.

Mission Control plans to issue commands to Spirit seeking additional data from the spacecraft during the subsequent few hours.

A news conference is planned for 1 p.m. EST today.

0545 GMT (12:45 a.m. EST)

Mars Global Surveyor did not detect a signal from the Spirit rover during an orbit over the landing site earlier tonight. However, controllers didn't expect Spirit would communicate with the orbiting spacecraft if the rover is truly in its "safe-mode" as engineers suspect.

Mission Control is gearing up to make direct Earth-to-Mars contact with the rover after the Sun rises at the Gusev Crater. Efforts are expected to begin around 3 a.m. Pacific time (6 a.m. EST; 1100 GMT) this morning. Using a communications channel that successfully received a beeping reply from the rover on Thursday, engineers hope they can get Spirit to transmit some data about its health.

Meanwhile, NASA's Mars scientist Jim Garvin appeared on The Late Show with David Letterman tonight, telling the CBS audience about exploration of the Red Planet and showing off pictures taken by Spirit.

"But the thing is busted now, isn't it?" Dave quipped.

"Well not exactly, no," Jim replied.

"You haven't heard from it in about a day, right?" Dave asked.

"We did hear from it (on Thursday). We've gotten a heart beat, and the rover now is in a special mode where it is protecting itself from the extremely cold environment on Mars. We're now communicating with it at very-low rate to tell it how to wake itself back up," Jim explained.

"I heard it was just transmitting, like Paul said, gibberish. You were getting back gibberish and were concerned there were problems with the hardware or software on the rover itself," Dave said.

"Well Dave, we have the best women and men trying to figure out what state it is in now. But we know it called home, we have this little heart beat -- beep, beep, beep -- and now we are going to try to diagnose the problem while we get ready for Opportunity to land early Sunday morning," Jim responded.

"So I guess calling AAA is out of the question?" Dave joked.

"That is true," Jim confirmed!

THURSDAY, JANUARY 22, 2004
2320 GMT (6:20 p.m. EST)

Controllers at the Jet Propulsion Laboratory believe the Mars rover Spirit has placed itself into "safe-mode" after experiencing some sort of problem, and officials remain hopeful that engineers can coax the craft back into operation.

"We are cautiously encouraged," JPL director Charles Elachi said on NASA Television a short time ago. "We are still concerned until we understand the problem and we address it."

Spirit abruptly stopped relaying its scientific and health data to Earth on Wednesday, sending a streak of fear through Mission Control when the rover went silent.

But earlier today, a signal was sent from Earth to Mars and Spirit responded with a simple tone.

"We did send a command to the spacecraft on a specific channel and we got a response back basically saying 'yeah, I am here' and we got exactly what we expected from it. So that gave us the indication, because it is on that specific channel that we got the response, is that the spacecraft is in safe-mode. Something kind of went wrong and it put itself into a safe-mode," Elachi said.

"The way we set the spacecraft is that if there is something abnormal, it goes into a certain safe-mode. The indication when we linked and it responded positively is that it is most likely in a certain safe-mode."

Controllers are now preparing for the next step in sorting out the problem and bringing Spirit back to useful life.

"We had to team go home and rest. At 5 o'clock tonight (8 p.m. EST; 0100 GMT) they come back and work a plan for the next communication opportunity which occurs at 3 a.m. Pacific time tomorrow morning (6 a.m. EST; 1100 GMT). We will be using the same channel that we used earlier this morning and we got the positive response."

Instead of asking for just a simple tone reply, controllers will instruct Spirit to play back some of its engineering data.

"We want some of its memory so we can do a diagnostic and understand what has happened, what are the corrective actions that need to be done and how do we bring it carefully and thoughtfully to its normal operational mode."

That direct Earth-to-Mars link occurs after Mars Global Surveyor and Mars Odyssey craft make overnight flights above the landing site. The orbiters will be in "listen-only" modes and not sending commands to Spirit. As a result, Elachi said he doesn't expect to hear anything from the rover during the passes if Spirit is in safe-mode.

Engineers are delving through the possible reasons that triggered Spirit to stop talking yesterday. Thus far, it is unknown exactly what caused the situation.

"There could be a possibility of some problem with the software in the spacecraft, similar to what happens in your computer," Elachi cited as one of many potential issues.

Options available to the team to fix the problem include correcting a software glitch, rebooting the entire spacecraft or, if it is a hardware failure, developing a plan to work around the faulty part.

"We have a very valuable asset up there that we did a lot of hard work to get it there safely. The public is all excited about it. So we need to do things methodically and carefully. There is nothing that is rushing us to actually go and do something immediately -- the spacecraft has power, the temperature seems to be appropriate," Elachi said.

"In any exploration you do, you always get anxious moments. Things had been working so well. When you are doing something which is 100 million miles away, roving on a different planet, there are going to be some anomalies or going to be some problems.

"So the key thing that is important is to stay calm, thoughtful and careful and not to react too quickly to when a problem actually occurs because sometimes you can do more harm than good by reacting too quick.

"It is a pretty smart machine that we have up there and the key thing that we are going to do next is to communicate with it tomorrow morning and ask it to send us some data down so we can do a diagnostic of what's the problem," Elachi said.

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

As project officials reported at the end of today's news conference, Mission Control received a radio signal from Spirit just before 12 noon EST. This simple message from the rover confirms it had received a transmission from Earth, and encourages engineers since it proves that Spirit is still alive and functioning.

Efforts to determine the cause of communications troubles with the rover are continuing. Engineers hope to get actual telemetry from Spirit to diagnose the rover's problem.

A pair of communication relay sessions are available tonight -- the first using Mars Global Surveyor at 10:10 p.m. EST; to be followed by Mars Odyssey's flight over the Gusev Crater landing site at 1:35 a.m. EST.

Direct communications between Spirit and antennas of NASA's Deep Space Network on Earth could resume at about 6 a.m. EST Friday, officials report.

1810 GMT (1:10 p.m. EST)

Here is project manager Pete Theisinger's briefing to reporters in the last hour, describing what has happened:

"At yesterday's press conference, we reported to you that we had had some communications issues with the rover, which we thought at the time was due to weather at the Canberra station and (Deep Space Network) configuration issues.

"We now know we have had a very serious anomaly on the vehicle, and our ability to determine exactly what has happened has been limited by our inability to receive telemetry from the vehicle, basically the last 12 hours or so.

"Let me kind of describe what the sequence of events have been.

"Yesterday afternoon, local solar time on Mars, actually about 1 o'clock, we sent to the vehicle at a command rate of 31.25 bits per second a sequence. We activated that sequence by command and we received a beacon response that indicated that we vehicle had received that sequence and that it was activating that sequence.

"After that time, a scheduled high-gain antenna pass at 2 o'clock in the afternoon, roughly, local solar time on Mars, did not occur.

"The 4:30 p.m. afternoon Mars Odyssey afternoon pass did not occur in the sense there was no indication by Odyssey that they received a UHF transmission.

"Last night, we had about a 1:30-2 a.m. Mars Global Surveyor pass and it was anomalous in the sense that Mars Global Surveyor believes it saw UHF transmission in its receiver telemetry but there was no data in the packets and the period of time that it believed it saw UHF telemetry was very, very short -- about two-and-a-half minutes compared to 12- or 13-minute overflight.

"The 4 a.m. Odyssey pass received no data, and this morning we did not have a direct-to-Earth link session -- we did not receive data on the normal direct-to-Earth session, nor did we receive data on what would have been a fault session at 11 a.m., which is where the spacecraft has entered fault mode, knows that, and chooses to communicate with us at a different time.

"The team has been meeting this morning and through the night working on a set of postulated fault scenarios. There is no one single fault that explains all the observables -- that we know of at the present time that we can conceive.

"We have been working on fault scenarios, we have been developing to-do lists. We have run yesterday's sequences through the test-bed (on Earth) with no anomalous results. So that is kind of our current state of knowledge."

At the end of the news conference, mission manager Jennifer Trosper came into the room and delivered an update to deputy project manager Richard Cook sitting at the briefing desk.

"If the spacecraft believes it's in a fault mode, its command rate should be 7.8 bits per second. We sent a beep today, this morning, about the time that we came down here to talk to you at 7.8. We sent a command that says if you get this send us a beep. And I'm told from Richard that Jennifer came down here to tell us that they think they got it," Theisinger said.

"That would tell us that the spacecraft thinks it's in the fault side of the tree some how for some reason. That would mean that we've got positive power, some elements of the software is working, once again the X-band system is working, the SSPA, the multi-space transponder, all that stuff is working so that would be more information -- good news. We need to confirm that. Data off the DSN sometimes needs double-checking. We'll let you know if that's for sure."

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

After a day of troubleshooting, engineers have not yet been able to restore communications with the Spirit rover, which stopped beaming back science and engineering data Wednesday. Project manager Pete Theisinger at the Jet Propulsion Laboratory in Pasadena, Calif., described the situation as "a very serious anomaly," but said it was too soon to say what might be causing the problem, whether it might be potentially fatal or whether the spacecraft can be restored to normal operation. Read our full story.

1703 GMT (12:03 p.m. EST)

Project manager Pete Theisinger says there has been a "very serious anomaly" on the rover.

No data has been received from the Mars Exploration Rover Spirit during several scheduled sessions over the past day, NASA says. Mars Global Surveyor received only a tone from the rover overnight but no telemetry.

Mission Control has launched recovery efforts to reestablish contact with the rover at Gusev Crater.

Details to follow!

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

A news conference is about to begin at the Jet Propulsion Laboratory on the status of Spirit and the loss of communications with the rover. We will update this page as soon as official information is available.

0640 GMT (1:40 a.m. EST)

The Mars Spirit rover stopped beaming scientific data to flight controllers Wednesday following thunderstorms at an Australian ground station that may have interfered with the daily uplink of critical computer commands. Read our full story.

0140 GMT (8:40 p.m. EST Wed.)

Spirit mission controllers did not receive expected data from the Mars Exploration Rover during scheduled communication passes on Wednesday, NASA announced a short while ago.

"Ground controllers were able to send commands to the Mars Exploration Rover Spirit early Wednesday and received a simple signal acknowledging that the rover heard them, but they did not receive expected scientific and engineering data during scheduled communication passes during the rest of that martian day," the Jet Propulsion Laboratory said in a statement.

"Project managers have not yet determined the cause, but similar events occurred several times during the Mars Pathfinder mission. The team is examining a number of different scenarios, some of which would be resolved when the rover wakes up after powering down at the end of the martian day (around midday Pacific time Wednesday).

"The next opportunity to hear from the vehicle is when the rover may attempt to communicate with the Mars Global Surveyor orbiter at about 8:30 p.m. Pacific time Wednesday night (11:30 p.m. EST; 0430 GMT). A second communication opportunity may occur about two hours later during a relay pass via the Mars Odyssey orbiter. If necessary, the flight team will take additional recovery steps early Thursday morning (the morning of sol 19 on Mars) when the rover wakes up and can communicate directly with Earth."

NASA says the next update on the rover's status will be announced at the daily news conference scheduled for Thursday at 9 a.m. Pacific time (12 p.m. EST; 1700 GMT).

WEDNESDAY, JANUARY 21, 2004
1915 GMT (2:15 p.m. EST)

Thunderstorms in Australia have created a slow workday on Mars.

The rainy weather at the Deep Space Network communications station in Canberra hampered the transmission of commands from Earth to the Spirit rover today.

"This is something that is kind of typical of spacecraft operations where there are days when it rains and things don't quite go the way you expect," mission manager Jennifer Trosper said. "So not a lot of science was done today, but the rover is in a very safe state. It's healthy."

The Rock Abrasion Tool grinding of "Adirondack" has been pushed back until at least tomorrow.

"When the rover woke up this morning we were actually over the Deep Space Network station in Canberra, Australia, because that was the part of Earth pointed at Mars at the time. There was lightning and there was rain and there was a thunderstorm in Canberra," Trosper told reporters at today's Spirit news conference.

"In the morning time frame -- Local Solar Time -- at the Gusev site between about 9 and 9:45 a.m. is an important time frame for us to take all of the work we did overnight, all the of sequences we built, the commands for the rover and send those. We transmit them to the rover. And then (Spirit) will start to act on those at about 9:45 Local Solar Time.

"As a result of the rain in Canberra today, the signal strengths were not able to be received by the rover. So we weren't able to transmit those commands to the rover. It received a weak signal from Earth because of the rain, so it actually didn't get all of data we wanted it to get. As a result, the rover did exactly what it was supposed to do and it continued to run yesterday's master sequence, which takes care of the rover in terms of keeping it awake during the day and continues to do communications."

A UHF communications session with the orbiting Mars Odyssey spacecraft was expected early this afternoon (Eastern Time).

"Depending on what we see in the UHF pass, it is possible we will wait to get all the data we need before we actually move on with the RAT'ing activities," Trosper said. "It is possible that we would RAT tomorrow, it is also possible that we would wait one more day to RAT to make sure we understand all of the things that executed and didn't execute on the spacecraft."

1803 GMT (1:03 p.m. EST)

An impressive color image has been released showing the empty lander base that delivered the Spirit rover to Mars. See the image here.

The view was taken by Spirit's panoramic camera on Sol 16 showing the rover's landing site, the Columbia Memorial Station, at Gusev Crater.

Data from the panoramic camera's green, blue and infrared filters were combined to create this approximate true color image.

TUESDAY, JANUARY 20, 2004

In the first patch of soil examined in detail by instruments aboard the Mars Spirit rover, scientists were surprised to find olivine, a silicate mineral that typically forms in igneous rocks of volcanic origin. It also weathers rapidly in the presence of water, posing a mystery of sorts for the rover science team. Read our full story.

1755 GMT (12:55 p.m. EST)

Spirit extended its arm today, reaching out and touching the rock called Adirondack.

The first activity was testing the "contact sensors" on the arm's RAT -- rock abrasion tool. The RAT could be used tomorrow to grind into the rock, but science team members are still debating whether to use the tool on this particular rock.

The arm was then used to snap microscopic images of the rock before switching to the Alpha Particle X-Ray Spectrometer instrument to study Adirondack's elemental composition. The APXS data collection will be completed shortly, allowing the Mossbauer Spectrometer to begin studying the rock overnight to look for iron-bearing minerals.

Officials report all continues to go well for Spirit and its exploration of the Gusev Crater.

MONDAY, JANUARY 19, 2004

Here is the latest dispatch from Mission Control:

NASA's Spirit rover has successfully driven to its first target on Mars, a football-sized rock that scientists have dubbed Adirondack.

The Mars Exploration Rover flight team at NASA's Jet Propulsion Laboratory, Pasadena, Calif., plans to send commands to Spirit early Tuesday to examine Adirondack with a microscope and two instruments that reveal the composition of rocks, said JPL's Dr. Mark Adler, Spirit mission manager.

The instruments are the Mossbauer spectrometer and the alpha particle X-ray spectrometer.

Spirit successfully rolled off the lander and onto the martian surface last Thursday. To make the drive to Adirondack, the rover turned 40 degrees in short arcs totaling 95 centimeters (3.1 feet). It then turned in place to face the target rock and drove four short moves straightforward totaling 1.9 meters (6.2 feet). The moves covered a span of 30 minutes on Sunday, though most of that was sitting still and taking pictures between moves. The total amount of time when Spirit was actually moving was about two minutes.

"These are the sorts of baby steps we're taking," said JPL's Dr. Eddie Tunstel, rover mobility engineer.

"The drive was designed for two purposes, one of which was to get to the rock," Tunstel said. "From the mobility engineers' standpoint, this drive was geared to testing out how we do drives on this new surface." Gathering new information such as how much the wheels slip in the martian soil will give the team confidence for more ambitious drives in future weeks and months.

"Adirondack is now about one foot (30 centimeters) in front of the front wheels," he said.

Scientists chose Adirondack to be Spirit's first target rock rather than another rock, called Sashimi, that would have been a shorter, straight-ahead drive. Rocks are time capsules containing evidence of the environmental conditions of the past, said Dr. Dave Des Marais, a rover science-team member from NASA Ames Research Center, Moffett Field, Calif. "We needed to decide which of these time capsules to open."

Sashimi appears dustier than Adirondack. The dust layer could obscure good observations of the rock's surface, which may give information about chemical changes and other weathering from environmental conditions affecting the rock since its surface was fresh. Also, Sashimi is more pitted than Adirondack. That makes it a poorer candidate for the rover's rock abrasion tool, which scrapes away a rock's surface for a view of the interior evidence about environmental conditions when the rock first formed. Adirondack has a "nice, flat surface" well suited to trying out the rover's tools on their first martian rock, Des Marais said.

"The hypothesis is that this is a volcanic rock, but we'll test that hypothesis," he said.

Spirit arrived at Mars Jan. 3 (EST and PST; Jan. 4 Universal Time) after a seven-month journey. In coming weeks and months, according to plans, it will be exploring for clues in rocks and soil to decipher whether the past environment in Gusev Crater was ever watery and possibly suitable to sustain life.

Spirit's twin Mars Exploration Rover, Opportunity, will reach Mars on Jan. 25 (EST and Universal Time; 9:05 p.m., Jan. 24, PST) to begin a similar examination of a site on the opposite side of the planet from Gusev Crater.

1810 GMT (1:10 p.m. EST)

Over the weekend, Spirit used its Mossbauer Spectrometer and Alpha Particle X-Ray Spectrometer instruments to study the soil in front of the rover. Results will be announced by scientists tomorrow.

The rover then made a short drive to a pyramid-shaped rock. Two other rocks in front of the lander base -- dubbed "Sushi" and "Sashimi" -- were passed up by scientists.

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

Spirit has been on the move this weekend, roving around the surface to reach rocks of interest to the scientists. NASA plans a 1 p.m. mission update briefing today.

FRIDAY, JANUARY 16, 2004

The Spirit Mars rover unlimbered its robot arm today and took the first microscopic images of another planet's surface. The smooth operation of the arm during the rover's 13th day on Mars was another major milestone in a mission that, so far, has sailed through activation and checkout without any significant problems. Read our full story.

1820 GMT (1:20 p.m. EST)

A new "overhead" view is created from Spirit photos to show the rover on the surface and the empty lander in the background. See the image here.

1810 GMT (1:10 p.m. EST)

A view of Spirit's arm in action is available here.

1803 GMT (1:03 p.m. EST)

At the daily Spirit rover news conference underway at JPL, mission officials are reporting that the scientific arm was successfully used during the just-completed workday. Hovering over the soil in front of the rover, the arm's Microscopic Imager examined the surface. Also, the arm's Rock Abrasion Tool was checked out.

THURSDAY, JANUARY 15, 2004

Starting late tonight, engineers will begin putting the rover's robot arm through its paces, checking out its rock-eroding abrasion tool and taking the first microscope images of the rocky soil directly in front of the rover. Late Friday, the arm's two spectrometers will make measurements and then, if all goes well, Spirit will begin moving again late Saturday or Sunday night. Read our full story.

1257 GMT (7:57 a.m. EST)

Data from the Spirit rover shows it completed this morning's drive off the lander at 3:41 a.m. EST. Confirmation was received on Earth just before 5 a.m. EST, verifying that Spirit had performed the 10-foot voyage on its own.

The move took approximately 78 seconds, ending with the back of the rover about 2.6 feet away from the lander egress ramp, officials report.

"It's as if we get to drive a nice sports car, but in the end we're just the valets who bring it around to the front and give the keys to the science team," says flight director Chris Lewicki.

That science team will be making daily decisions about where to send Spirit as the roving robot geologist uses its instruments to study rocks, the Martian soil and atmosphere. Starting late tonight (Earth time) the rover's science arm will be checked out.

TODAY'S IMAGES OF ROVER DRIVE
   SPIRIT'S VIEW LOOKING AT LANDER
   FORWARD-LOOKING VIEW FROM SPIRIT
   3D IMAGE OF THE EMPTY LANDER

1101 GMT (6:01 a.m. EST)

Read our story summarizing this morning's events.

1015 GMT (5:15 a.m. EST)

A news conference from the Jet Propulsion Laboratory is upcoming at 5:45 a.m. EST for Spirit officials to talk about this morning's successful drive.

1004 GMT (5:04 a.m. EST)

To a loud round of applause, the first full image of the empty lander has been received from Spirit.

1001 GMT (5:01 a.m. EST)

The tiny thumbnail image has been received from Spirit showing the lander behind the rover. The lander safely delivered Spirit to the Martian surface but it is no longer needed by the rover.

0957 GMT (4:57 a.m. EST)

Six-wheeling on Mars! Spirit has successfully driven off its lander and is now sitting on the surface of the Red Planet!

"Sounds like it was a nice trip. All we need now are the pictures!" flight director Chris Lewicki told his team in Mission Control as engineering data from the rover was received on Earth. A rear-facing camera on Spirit should have snapped a view of the lander. It should be available shortly.

The rover is ready to embark on its three-month expedition to explore the Gusev Crater for evidence of past water.

0953 GMT (4:53 a.m. EST)

Signals from the Spirit rover are now being received on Earth. It will take a little while before controllers will be able to announce whether the drive has occurred as planned.

0946 GMT (4:46 a.m. EST)

Young Sofi Collis, who wrote the winning essay in the Mars rover naming contest, is in Mission Control this morning. For more on the contest that selected the Spirit and Opportunity names, click here.

0920 GMT (4:20 a.m. EST)

By this time, Spirit should have completed its drive onto the surface. The rover is then programmed to take imagery of the lander base with its rear-facing camera system. And since Spirit has moved, it has to find the Sun -- which allows the rover to determine its orientation in order to point the high-gain antenna toward Earth for the upcoming communications session.

0850 GMT (3:50 a.m. EST)

Spirit Mission Control issued commands to the rover about 30 minutes ago to drive off the lander. The craft will perform the 10-foot journey on its own. Confirmation of Spirit's roll onto the surface will be received on Earth during a communications session between 4:52 and 5:22 a.m. EST.

WEDNESDAY, JANUARY 14, 2004

The Spirit Mars rover has successfully completed a 115-degree "turn in place" atop its lander and now stands poised to roll off onto the martian surface early Thursday. The long-awaited 10-foot move is expected to be completed just before dawn East Coast time. If all goes well, a rear-facing navigation camera will take a parting snapshot of the lander as Spirit's surface exploration finally gets underway. Read our full story.

1707 GMT (12:07 p.m. EST)

Spirit has completed its second and third turns. Those moves went according to plan overnight, officials report, and the rover is now pointing 115 degrees away from its original heading. All systems are "go" for Thursday morning's drive of Spirit off the lander and onto the surface of the Red Planet.

TUESDAY, JANUARY 13, 2004

An exploration strategy has been developed for the Spirit rover after determining the craft's exact location. A close-by crater and a cluster of hills off in the distance are prime scientific targets. "We now know where we are and with that knowledge, we can now intelligently plan a mission-long traverse, a mission-long plan for exploration of this landing site," science chief Steve Squyres says. Read our full story.

2325 GMT (6:25 p.m. EST)

In the end, it was probably just as well flight controllers couldn't watch the Spirit lander's hair-raising descent to the rocky floor of Gusev Crater January 3. Even a base-jumping skydiver might have experienced a jolt of fear given the last-second maneuvers required to turn a high-speed impact into a safe, if bumpy, landing. Read our full story.

1704 GMT (12:04 p.m. EST)

The final umbilical running between the lander and rover was successfully cut overnight, and Spirit performed a 45-degree turn in place atop the lander. This was the first in a series of three turns to position the rover in the direction for the drive to the surface later this week.

MONDAY, JANUARY 12, 2004

Rock fragmentation at rover site possibly result of water
The first 360-degree panorama taken by the Spirit rover's main camera system provides a spectacular view of Gusev Crater's cracked and churned-up floor, including an abundance of small, cracked rocks and fragments that could be the result of water-driven erosion in the distant past, researchers said today. Read our full story.

1720 GMT (12:20 p.m. EST)

During the last day on Mars, Spirit focused on science activities by using the Mini-TES and Pancam devices for imaging of the landing site. On Earth, the rover driveoff sequences underwent a dress rehearsal using a model with no major problems uncovered.

Later tonight, the final umbilical between the lander base and Spirit will be severed. The rover then performs the first of three turns to reach the egress path. The drive to the surface is still scheduled for Wednesday night/Thursday morning.

SUNDAY, JANUARY 11, 2004

Engineers now think they'll be ready to roll the Spirit rover off its lander and onto the martian surface early Thursday, a day later than had been hoped, to accommodate rehearsals and a two-day procedure to rotate the rover into position for its long-awaited egress. Read our full story.

1725 GMT (12:25 p.m. EST)

On the just-completed Sol 8 workday for Spirit, the two middle wheels were released from the lander as planned and the science arm was unlocked from its launch location and moved to the "drive" position for the upcoming roll to the surface.

Sol 9 that begins tonight (Earth time) will be dedicated to science activities.

On Monday night, the final cable between the lander and rover -- a power and communications umbilical -- will be cut. Spirit then will perform the first of three turns on the lander to reach an alternate driveway. This first turn will be about 45 degrees as the rover moves from a southward heading to the lander egress path facing northwest. The south path is partially blocked by an airbag that prevents a straight drive to the surface.

Tuesday night will see two more turns on the lander -- to 95 degrees and then to the final 115-120 degree position. After every turn the rover's hazard cameras will snap views to ensure there are no problems before continuing.

Spirit's drive off the lander has been pushed back one day to Wednesday night/Thursday morning -- Sol 12. This is a delay to the schedule announced yesterday. Officials caution that activities could be postponed further depending on how well the turns go and the outcome of engineering testing on Earth.

At the Jet Propulsion Laboratory's landing site mockup, a dress rehearsal is planned today to practice the procedures that Spirit will use.

SATURDAY, JANUARY 10, 2004

The Spirit Mars rover completed its multi-part "stand-up" sequence today, the most complex set of mechanical deployments ever attempted by a robotic spacecraft. Resting on its now unfolded, locked-in-place undercarriage and its six ridged wheels, Spirit should be ready to roll off its lander and onto the martian surface by early Wednesday morning East Coast time to begin its long-await exploration of Gusev Crater.

On any other day, that would be a major milestone. But Wednesday morning also is the day President Bush is expected to announce a new space initiative that would end shuttle operations by 2010 and send astronauts to the moon by the middle of the next decade. The ultimate goal is to expand humanity's exploration of the solar system to Mars.

Read our full story.

1830 GMT (1:30 p.m. EST)

Today was a very successful day for the Spirit rover, mission controllers report, and the mobile robotic geologist could drive off its lander earlier than once envisioned.

The lift mechanism used previously to raise up the rover was retracted back into the lander overnight. Also, Spirit's rear wheels were deployed. The rover is now standing on its six wheels, almost ready to drive on the Martian surface.

On the upcoming workday that begins tonight (Earth time), the middle wheels will be released from the lander and the moveable arm holding science instruments will be unlocked from its launch position and put into the "stowed" position for exiting the lander.

On the Sunday night workday, the final cable line running from the lander to Spirit will be severed -- at which point the base and rover will be separated. The lander becomes a dead platform.

With a puffed up airbag still hampering the forward driveway, engineers have done a test with a model on Earth to determine what would happen if Spirit took that path. The demonstration revealed that there was a chance the left-rear solar panel could brush the bag during the driveoff.

As a result, Spirit will make a 120-degree turn on the lander -- probably on Monday night -- to reach a different exit path. The rover is currently facing south and will turn to head toward the northwest.

The big moment of rolling onto the surface is expected Tuesday night/Wednesday morning.

Yesterday, officials were estimating the lander egress would occur late next week. But it now appears Tuesday night is achievable.

FRIDAY, JANUARY 9, 2004
1735 GMT (12:35 p.m. EST)

The latest effort to further retract the airbag on the front driveway for Spirit has failed. Therefore, officials are planning to command the rover to make a turn on the lander and exit on one of the other pathways to the surface. This is an option that was rehearsed on Earth and should be no impact to the mission.

Mission manager Matt Wallace says Spirit will drive off the lander late next week.

During the workday that begins tonight, the rest of the stand-up procedures will be performed -- retracting the lift mechanism and deploying the rear wheels.

1730 GMT (12:30 p.m. EST)

The first data from Spirit's Mini-Thermal Emission Spectrometer has been released. This instrument detects the infrared light, or heat, emitted by objects. A wide view of the landing site is available here.

A closer view of the landscape is available here.

1707 GMT (12:07 p.m. EST)

The Mars rover Spirit successfully stood up overnight, deploying its front wheels and achieving a key milestone in preparation for driving off the lander next week. An image from the rover's front hazard avoidance camera is available here.

The deflated airbag partially blocking the front exit from the lander is also visible.

THURSDAY, JANUARY 8, 2004

Engineers are having problems fully retracting partially collapsed airbags under the Spirit rover's landing platform that may hamper efforts to drive the vehicle straight off and onto the martian surface. Other exit routes are available, however, and mission manager Matt Wallace said he believed Spirit could simply drive over the airbag material with no problems. Read our full story.

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

The overnight attempt on Sol 5 to further retract that stubborn airbag was not successful, officials reported at today's noon EST news conference. One of the lander's petals was raised 20 degrees in a "lift and tuck" procedure to retract the bag. On the upcoming Sol 6 workday, the retraction mechanism will attempt 6 revolutions to pull in the bag.

The bag in question is hampering the desired forward route off the lander for Spirit. If the pathway can't be cleared, the rover could turn on the lander and roll off another direction.

Meanwhile, controllers plan to perform the first two portions of the rover's stand up procedures on Sol 6. Step one will be raising the rover's body with a lift mechanism. Step two will see the two front wheels -- stowed for launched -- finally deployed.

Image and science collections will continue on the upcoming day.

The next mission update news conference is planned for tomorrow.

1708 GMT (12:08 p.m. EST)

Check out the Gusev Crater landing site in a new color image. NASA has just released the image from the Spirit rover. You can download the image here.

The caption: This latest color "postcard from Mars," taken on Sol 5 by the panoramic camera on the Mars Exploration Rover Spirit, looks to the north. The apparent slope of the horizon is due to the several-degree tilt of the lander deck.

On the left, the circular topographic feature dubbed Sleepy Hollow can be seen along with dark markings that may be surface disturbances caused by the airbag-encased lander as it bounced and rolled to rest. A dust-coated airbag is prominent in the foreground, and a dune-like object that has piqued the interest of the science team with its dark, possibly armored top coating, can be seen on the right.

Read our earlier Mission Status Center coverage.