BY JUSTIN RAY

Additional coverage for subscribers:
VIDEO: WEDNESDAY'S PICTURE AND UPDATE BRIEFING PLAY
VIDEO: TUESDAY'S PICTURE AND UPDATE BRIEFING PRESENTATION | Q&A
VIDEO: MONDAY AFTERNOON'S UPDATE PRESENTATION | Q&A
VIDEO: HOW MARS ORBITER GOT THE PARACHUTE PHOTO PLAY

VIDEO: PHOENIX LANDS ON MARS! PLAY
VIDEO: MIDNIGHT POST-LANDING BRIEFING PRESENTATION | Q&A
VIDEO: POST-LANDING INTERVIEW WITH MARS PROGRAM DIR. PLAY
VIDEO: POST-LANDING INTERVIEW WITH PRINCIPAL INVESTIGATOR PLAY
VIDEO: POST-LANDING INTERVIEW WITH PROJECT MANAGER PLAY

VIDEO: SUNDAY'S PRE-LANDING STATUS PRESENTATION | Q&A
VIDEO: SATURDAY STATUS BRIEFING PRESENTATION | Q&A
VIDEO: ENTRY, DESCENT AND LANDING EXPLAINED PLAY
VIDEO: THURSDAY STATUS BRIEFING PRESENTATION | Q&A
VIDEO: ANIMATION OF PHOENIX MISSION WITH NARRATION PLAY
VIDEO: PHOENIX LAUNCHES! PLAY
VIDEO: HIGHLIGHTS FROM MARS ROVER SPIRIT'S LANDING PLAY
VIDEO: HIGHLIGHTS FROM MARS ROVER OPPORTUNITY'S LANDING PLAY
MORE: PHOENIX VIDEO COVERAGE
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FRIDAY, MAY 30, 2008

Here is the official press release from today:

TUCSON, Ariz.-- Scientists have discovered what may be ice that was exposed when soil was blown away as NASA's Phoenix spacecraft landed on Mars last Sunday, May 25. The possible ice appears in an image the robotic arm camera took underneath the lander, near a footpad.

"We could very well be seeing rock, or we could be seeing exposed ice in the retrorocket blast zone," said Ray Arvidson of Washington University, St. Louis, Mo., co-investigator for the robotic arm. "We'll test the two ideas by getting more data, including color data, from the robotic arm camera. We think that if the hard features are ice, they will become brighter because atmospheric water vapor will collect as new frost on the ice.

"Full confirmation of what we're seeing will come when we excavate and analyze layers in the nearby workspace," Arvidson said.

Testing last night of a Phoenix instrument that bakes and sniffs samples to identify ingredients identified a possible short circuit. This prompted commands for diagnostic steps to be developed and sent to the lander in the next few days. The instrument is the Thermal and Evolved Gas Analyzer. It includes a calorimeter that tracks how much heat is needed to melt or vaporize substances in a sample, plus a mass spectrometer to examine vapors driven off by the heat. The Thursday, May 29, tests recorded electrical behavior consistent with an intermittent short circuit in the spectrometer portion.

"We have developed a strategy to gain a better understanding of this behavior, and we have identified workarounds for some of the possibilities," said William Boynton of the University of Arizona, Tucson, lead scientist for the instrument.

The latest data from the Canadian Space Agency's weather station shows another sunny day at the Phoenix landing site with temperatures holding at minus 30 degrees Celsius (minus 22 degrees Fahrenheit) as the sol's high, and a low of minus 80 degrees Celsius (minus 112 degrees Fahrenheit). The lidar instrument was activated for a 15-minute period just before noon local Mars time, and showed increasing dust in the atmosphere.

"This is the first time lidar technology has been used on the surface of another planet," said the meteorological station's chief engineer, Mike Daly, from MDA in Brampton, Canada. "The team is elated that we are getting such interesting data about the dust dynamics in the atmosphere."

The mission passed a "safe to proceed" review on Thursday evening, meeting criteria to proceed with evaluating and using the science instruments.

"We have evaluated the performance of the spacecraft on the surface and found we're ready to move forward. While we are still investigating instrument performance such as the anomaly on TEGA [Thermal and Evolved Gas Analyzer], the spacecraft's infrastructure has passed its tests and gets a clean bill of health," said David Spencer of NASA's Jet Propulsion Laboratory, Pasadena, Calif., deputy project manager for Phoenix.

"We're still in the process of checking out our instruments," Phoenix project scientist Leslie Tamppari of JPL said. "The process is designed to be very flexible, to respond to discoveries and issues that come up every day. We're in the process of taking images and getting color information that will help us understand soil properties. This will help us understand where best to first touch the soil and then where and how best to dig."

1810 GMT (2:10 p.m. EDT)

A new image from the camera on Phoenix's robot arm has revealed what could be ice or rock exposed by the exhaust from the probe's landing rockets, Mission co-scientist Ray Arvidson of Washington University in St. Louis told a news conference this afternoon. More pictures will be taken to determine what is this flat exposed material.

A short circuit has been discovered within the Thermal and Evolved-Gas Analyzer instrument but scientists are hopeful they can work around the problem. The instrument will analyze soil samples dug up by the robot arm.

THURSDAY, MAY 29, 2008
1855 GMT (2:55 p.m. EDT)

After being folded up on Earth a year ago, the Phoenix spacecraft's robot arm finally got to move Wednesday as flight controllers began the process of unstowing the scoop-laden appendage that will dig up samples of the frozen martian terrain for study.

Flexing its wrist to free one restraint, the elbow lifted the forearm from a second restraint and then the 7.7-foot-long arm raised above its cradle that had protected the critical device during the rigors of launch last summer and Sunday night's descent onto the arctic plains of Mars.

"Our arm was cooped up in our restraints for 14 months. It was raring to go. It's busted loose now," said Matt Robinson, robotic arm flight software lead.

Unstowing the arm required all four joints to move, Robinson said, adding that the telemetry from the spacecraft indicated the joints were healthy.

"Things are going remarkably well," said Barry Goldstein, the Phoenix project manager. "We've even exceeded our optimistic goals."

Commands uplinked to Phoenix this morning will extend the arm and perform further checks of the joints at the range of temperatures seen at the landing site.

Instrument testing and practice sessions moving the arm will continue over the next few days in preparation for the start of science operations next week.

During the three-month mission, the arm will dig small trenches to reach water ice located just below the surface and deliver samples to instruments on the lander's science deck. The experiments are designed to tell scientists whether the northern plains could be a habitable zone for life.

Small rocks in the area where the digging will occur have been given names from classic fairy tales and folk legends, including Humpty Dumpty, Wall, King's Men, King's Horses, Sleepy Hollow, Headless, Ichabod and Alice.

"The rocks are a little more than fist-sized," said Peter Smith, principal investigator for the Phoenix mission. "These are not large rocks. We should be able to actually move them with our robotic arm and check out what's underneath."

A photo of the workspace depicting the rock sizes is available here. An image with the rock names can be seen here.

"As we scan across, we have lots of places between the rocks where we can use our robotic arm and dig down under the surface," Smith said.

"Just look at that workspace. It just could not be better. So I'm really looking forward over the next 90 sols for some major scientific breakthroughs," Goldstein added.

The weather report from the Canadian meteorology package on Phoenix landing site from Sol 2 was sunny with moderate dust, a high temperature of -22 degrees Fahrenheit and a low of -112 degrees F, according to Jim Whiteway, Canadian science team lead from York University.

0435 GMT (12:35 a.m. EDT)

A large batch of pictures was broadcast from the Phoenix lander late Wednesday, confirming the craft's robotic arm had taken initial steps to unstow itself earlier in the day.

Three remarkable images to see include a stitched picture giving an overhead perspective of the lander, plus two partial panoramas of the lander and its raised arm. See those pans here and here.

WEDNESDAY, MAY 28, 2008
1845 GMT (2:45 p.m. EDT)

Freeing its robotic arm from launch restraints is today's primary task for the Phoenix lander, a day after communications snags prevented commands from reaching the spacecraft.

"The spacecraft is in excellent health, absolutely excellent health. I know we had a bit of drama here yesterday relative to communications. But there never was an issue with Phoenix," said Barry Goldstein, the Phoenix project manager.

Trouble with the ultra-high frequency radio aboard the Mars Reconnaissance Orbiter meant the lander never received the day's instructions relayed from Earth. Subsequent communications between MRO and Phoenix did occur, but flight controllers have decided to make the Mars Odyssey orbiter the prime communicator for now. Odyssey will perform the daily morning transmission of work commands to Phoenix and the daily evening retrieval of lander data.

"Odyssey is doing the a.m. pass and the p.m. pass, and we'll keep that up indefinitely until we have utter confidence that we can rely on MRO," Goldstein said.

Since the yesterday's commands didn't reach Phoenix, the lander continued running on stored instructions loaded previously. But new work orders were successfully transmitted via Odyssey today that will begin deploying the robot arm.

"We did good operations on the surface yesterday. We've uplinked the sequence this morning and hopefully by tomorrow we'll be able to show some partially-deployed robotic arm images," Goldstein said.

"I believe the earliest that we might be digging would be the early-to-the-midpart of next week. We are going to take our time...Please be patient with us."

Today's unstowing of the robot arm is a series of moves, starting with rotating the wrist to release the forearm from the launch restraint. Further moves free the elbow from its launch restraints and lifts the elbow from underneath the biobarrier, according to Bob Bonitz, the arm manager.

Engineers are still investigating the MRO radio system to understand what went wrong.

1812 GMT (2:12 p.m. EDT)

A new color photo has been released taken yesterday by Phoenix's Surface Stereo Imager. The view looks toward the northwest, showing polygonal terrain near the lander and out to the horizon. See the image here.

0400 GMT (12:00 a.m. EDT)

A UHF radio aboard NASA's Mars Reconnaissance Orbiter suffered a transient glitch Tuesday, preventing engineers from relaying the day's flight plan to the Phoenix lander, parked near the red planet's northern polar cap. In the absence of fresh instructions, the lander executed stored commands to snap additional pictures of its surroundings while engineers worked to resolve the MRO problem. Late Tuesday, the radio was back in operation, NASA reported on its Phoenix mission web site, and a fresh set of images was relayed back to Earth.

Read our full story.

0245 GMT (10:45 p.m. EDT Tues.)

The Mars Reconnaissance Orbiter established a successful communications link with the Phoenix lander on Tuesday evening, collecting images and information from the lander and then relaying the data back to Earth.

"The UHF radio system used by the orbiter to communicate with the lander had gone into a standby mode earlier Tuesday for a still undetermined cause," a NASA statement said. "This prevented sending Phoenix any new commands from Earth on Tuesday. Instead, the lander carried out a backup set of activity commands that had been sent Monday."

The Mars Odyssey orbiter is scheduled to provide Phoenix with new commands on Wednesday morning that will include initial steps to free the lander's robotic arm from its stowed position. The wrist will be unlatched and the elbow flexed for the first time.

TUESDAY, MAY 27, 2008
1950 GMT (3:50 p.m. EDT)

Two additional must-see pictures from the Mars Reconnaissance Orbiter's high-resolution camera show the entire scene around the landing site, including the lander, the discarded heat shield, backshell and parachute.

The color image was taken Monday, about 22 hours after landing. The parachute and lander are about 300 meters, roughly 1,000 feet, apart.

The other photo is stunning. It shows Phoenix as it was descending on the parachute Sunday evening with a huge crater in the background. See that image here.

"Phoenix appears to be descending into the 10 kilometer, or 6-mile, crater, but is actually 20 kilometers, or about 12 miles, in front of the crater," says the camera's principal investigator, Alfred McEwen of the University of Arizona, Tucson.

1840 GMT (2:40 p.m. EDT)

The communications problem with the Mars Reconnaissance Orbiter has delayed today's planned activities aboard the Phoenix lander, which had included the first steps to unstow the craft's robotic arm.

An apparent glitch with the ultra-high frequency radio aboard MRO prevented controllers from getting the day's work instructions relayed to Phoenix, leaving the lander waiting for new commands.

"MRO is right in the middle of trying to understand what happened and turn that radio back on," said Fuk Li, director of the Mars Exploration Directorate at the Jet Propulsion Laboratory.

"I would call it sequence deferred but not sequence deleted...The hope, clearly, is that the MRO radio will turn back on and we'll just go back to normal. If not, we'll just have to ask Odyssey to do double-duty."

Should MRO not be able to provide the communications relay between Phoenix and Earth, the Mars Odyssey orbiter would enable the lander's mission to continue, Li stressed.

"We'll just have to ask Odyssey to work harder."

The communications architecture for the Phoenix mission uses the MRO and Mars Odyssey satellites orbiting the red planet to route commands from Earth to the lander and also relay data from the lander back to Earth.

"The whole MRO spacecraft is working fine. The transient event occurred with the UHF radio that MRO uses to communicate with Phoenix," Li said.

Without receiving the new command sequence from Earth today, Phoenix will continue its operating plan of taking temperature measurements and collecting more stereo imagery, Li said.

Peter Smith, principal investigator for the Phoenix mission, said controllers hope to accomplish today's original activities on Wednesday. The robot arm's first touch of the martian soil could occur this weekend, followed by delivering the initial samples to the instruments on the lander deck early next week.

1812 GMT (2:12 p.m. EDT)

Another amazing view of Phoenix taken by the Mars Reconnaissance Orbiter was just released. It shows the lander on the surface after its touchdown. See the image here.

1805 GMT (2:05 p.m. EDT)

It is Sol 2 for Phoenix on the surface of the red planet. Current martian local time at the landing site is just past 2 p.m.

The lander is running on stored program commands. Efforts to send new sequences to Phoenix failed earlier today, however, due to a problem with the UHF radio communications system aboard the Mars Reconnaissance Orbiter. The communications architecture for the Phoenix mission uses the MRO and Mars Odyssey satellites orbiting Mars to route commands from Earth to the lander and also relay data from the lander back to Earth.

1105 GMT (7:05 a.m. EDT)

Another wide view of the landing area was released by the Phoenix team overnight. See the image here.

0210 GMT (10:10 p.m. EDT Mon.)

Check out a 3-D image of the Phoenix lander here.

0105 GMT (9:05 p.m. EDT Mon.)

Communications from the Phoenix lander late Monday indicate the spacecraft remains in good health following its first full day on the red planet.

Additional pictures beamed back from the lander include views of the craft's surroundings, including one showing what could be a piece of the discarded landing system, another that features a blip that's either part of the descent hardware or just a glitch in the image and also a wide view of the region.

MONDAY, MAY 26, 2008
2035 GMT (4:35 p.m. EDT)

Still basking in the elation of a successful Mars landing, engineers with the Phoenix program unveiled a dramatic photo today showing the spacecraft descending to the martian surface under its parachute Sunday. The black-and-white photo, shot by NASA's Mars Reconnaissance Orbiter spacecraft as it sailed overhead, shows the inflated parachute and the backshell supporting Phoenix dangling below, somewhere between 10,000 and 1,000 feet above the surface.

Read our full story.

1830 GMT (2:30 p.m. EDT)

Two additional images released at this afternoon's news briefing include an approximate true-color image and a close-up shot showing the disturbed surface around one of the lander footpads.

1805 GMT (2:05 p.m. EDT)

During the Phoenix spacecraft's descent last night, the Mars Reconnaissance Orbiter captured an utterly remarkable picture of the lander riding its parachute. The image was taken by the orbiter's High Resolution Imaging Science Experiment (HiRISE) camera.

See the image here.

The NASA caption for the image:

From a distance of about 472 miles above the surface of the Red Planet, Mars Reconnaissance Orbiter pointed its HiRISE obliquely toward Phoenix shortly after it opened its parachute while descending through the Martian atmosphere. The image reveals an apparent 30-foot-wide parachute fully inflated. The bright pixels below the parachute show a dangling Phoenix. The image faintly detects the chords attaching the backshell and parachute. The surroundings look dark, but corresponds to the fully illuminated Martian surface, which is much darker than the parachute and backshell.

Phoenix released its parachute at an altitude of about 7.8 miles and a velocity of 1.7 times the speed of sound.

The HiRISE, acquired this image on May 25 at 7:36 p.m. Eastern Time. It is a highly oblique view of the Martian surface, 26 degrees above the horizon, or 64 degrees from the normal straight-down imaging of Mars Reconnaissance Orbiter. The image has a scale of 0.76 meters per pixel.

This image has been brightened to show the patterned surface of Mars in the background.

Another version of the image not brightened is available here.

0800 GMT (4:00 a.m. EDT)

The Phoenix lander that touched down on Mars Sunday appears healthy and should be ready to begin digging for ice within a week or so, NASA officials said early Monday, after engineers complete initial checkout and collect more photos to help characterize the landing site.

Read our full story.

0440 GMT (12:40 a.m. EDT)

Color pictures of the Phoenix landing site are available here and here.

0430 GMT (12:30 a.m. EDT)

The sharp-eyed Mars Reconnaissance Orbiter on Monday will attempt to image the Phoenix spacecraft on the surface. The believed landing site coordinates have been given to the MRO team to observe the lander.

Mission officials say the post-landing events, including deployment of the masts for the stereo camera and weather station and opening of the bio-barrier covering the stowed robotic arm, all occurred.

"Phoenix is an amazing machine and it was built and flown by an amazing team. Through the entire entry, descent and landing phase, it performed flawlessly," said Ed Sedivy, Phoenix program manager at Lockheed Martin Space Systems Company. "The spacecraft stayed in contact with Earth during that critical period and we received a lot of data about its health and performance. I'm happy to report it's in great shape."

0415 GMT (12:15 a.m. EDT)

"I'm truly pleased that we are back at Mars. The journey feels much longer than 422 million miles. We have gone through challenges and trying times, and now we're going through jubilation," said Peter Smith, of the University of Arizona, principal investigator for the Phoenix mission. "I'm very grateful of NASA, JPL and Lockheed Martin for making this mission a reality and for allowing us to advance the scientific study of our neighboring planet."

0214 GMT (10:14 p.m. EDT)

Additional landscape images are available here and here

0212 GMT (10:12 p.m. EDT)

More landscape images are available here and here

0210 GMT (10:10 p.m. EDT)

Further landscape images are available here and here.

0205 GMT (10:05 p.m. EDT)

Another image of the landscape is posted.

0157 GMT (9:57 p.m. EDT)

Take a look at some of the first images from Phoenix showing the landing site landscape, one of the solar arrays and one of the lander's legs.

0154 GMT (9:54 p.m. EDT)

The first photos from Phoenix are streaming back to Earth showing the deployed solar arrays, the lander's feet on the surface, the craft's science instrument deck and the flat terrain of the northern plains.

0150 GMT (9:50 p.m. EDT)

Contact with Phoenix has been established by the Mars Odyssey orbiter to begin this data transmission back to Earth.

0140 GMT (9:40 p.m. EDT)

"We've passed the hardest part and we're breathing again, but we still need to see that Phoenix has opened its solar arrays and begun generating power," said Barry Goldstein, the Phoenix project manager.

The next telemetry relay from Phoenix via the Mars Odyssey orbiter is expected shortly. That data should tell flight controllers that the solar arrays are deployed and the masts for the stereo camera and weather station have swung to their vertical positions as planned. The first images should be contained in the transmission, too.

"What a thrilling landing! But the team is waiting impatiently for the next set of signals that will verify a healthy spacecraft," said Peter Smith of the University of Arizona, principal investigator for the Phoenix mission. "I can hardly contain my enthusiasm. The first landed images of the Martian polar terrain will set the stage for our mission." The landing occurred at 7:53:44 p.m. EDT, Earth-receive time, JPL says.

0133 GMT (9:33 p.m. EDT)

The landing point appears to be 68.22 degrees latitude and 234.3 degrees longitude.

0055 GMT (8:55 p.m. EDT)

A post-landing poll of flight controllers is being conducted. There were no system problems reported in the initial data received from Phoenix.

Parachute deployment appeared to be about 7 seconds later than predicted. Trajectory information looked normal.

0045 GMT (8:45 p.m. EDT)

With Newtonian inevitability, NASA's Phoenix lander plunged into the martian atmosphere today at 12,700 mph and then used atmospheric friction, a large parachute and finally, 12 individuallly controlled rocket engines to complete an automated landing near the red planet's northern polar cap. The successful touchdown at 7:53 p.m. marked a dramatic reversal of fortune for NASA, which suffered a devastating failure the last time the agency attempted a rocket-powered descent to Mars nine years ago.

This time around, telemetry from Phoenix, relayed to Earth through NASA's Mars Odyssey orbiter flying high above the landing site, indicated the small, 760-pound lander completed its action-packed descent as planned and in good health.

"Phoenix has landed! Phoenix has landed! Welcome to the northern plains of Mars!" mission commentator Richard Kornfeld exclaimed from the control center at the Jet Propulsion Laboratory.

Read our full story.

0022 GMT (8:22 p.m. EDT)

"This spacecraft has been a flawless performer since launch, and it continued this all the way to the surface. It was just flawless. It was unbelievable. An unbelievable performance," says Doug McCuistion, director of NASA's Mars exploration program.

0012 GMT (8:12 p.m. EDT)

"It's in a nice flat place, very safe and happy," says Peter Smith, the Phoenix principal investigator.

0006 GMT (8:06 p.m. EDT)

"In my dreams, it couldn't have gone as perfectly as it went tonight," says Barry Goldstein, the Phoenix project manager.

"I'm in shock. We had all the signals. Everything."

0004 GMT (8:04 p.m. EDT)

In that initial minute of data from Phoenix via Mars Odyssey after landing indicates the lander has just one-quarter degree of tilt and is oriented to deploy its solar arrays for an east-west orientation as planned for maximum power, reports Barry Goldstein, Phoenix project manager from the Jet Propulsion Laboratory.

2359 GMT (7:59 p.m. EDT)

Following its touchdown, Phoenix will wait for nearly 20 minutes before deploying its two power-generating solar arrays. This pause allows the dust kicked up during the landing to settle and not collect on the arrays.

The next communications pass will confirm the arrays are unfurled and possibly return the first pictures taken by Phoenix.

2356 GMT (7:56 p.m. EDT)

The communications relay through the Mars Odyssey orbiter has concluded a minute after touchdown as planned. The next window will occur when Odyssey flies over the landing site on the next orbit, a little less than two hours from now.

2354 GMT (7:54 p.m. EDT)

Welcome to Mars!

2353 GMT (7:53 p.m. EDT)

TOUCHDOWN! Phoenix has landed! The spacecraft has reached the icy-rich arctic plains of the red planet to taste the water of Mars!

2353 GMT (7:53 p.m. EDT)

Lander separation. The lander has separated from the parachute and backshell structure. Phoenix will freefall for a few moments before the pulse thrusters begin firing to further slow the craft to the surface for a 5 mph touchdown speed. This separation event should have occurred about six-tenths of a mile above the surface while descending at 125 mph.

The dozen descent thrusters pulse on and off to control pitch, yaw and roll, each generating about 66 pounds of force.

Just before touchdown, the lander will perform a pirouette to achieve an orientation that maximizes the solar exposure on the spacecraft during its mission on the surface.

2351 GMT (7:51 p.m. EDT)

Radar starts. About 75 seconds after the parachute was deployed and some 140 seconds before landing, the spacecraft's radar becomes active to measure the distance to the ground, descent speed and horizontal velocity and feed those readings into the onboard computer. The information is taken 10 times per second.

2350 GMT (7:50 p.m. EDT)

Parachute deploy. Descending through an altitude of 8 miles and traveling about 1.7 times the speed of sound, the large parachute has deployed! In the first 15 seconds after the chute is unfurled, Phoenix will decelerate to a relatively slow 250 miles an hour.

And in the next few seconds, the heat shield will be jettisoned to expose the bottom of the Phoenix lander, allowing the craft's three legs to unfold in preparation for touchdown.

2349 GMT (7:49 p.m. EDT)

"We spend four minutes going through the atmosphere, taking out 94 percent of the energy. By the time the heat shield has done its job, we're down to 1,100 miles per hour at which point we fire a mortar and you'll see the parachute deploy," Barry Goldstein, Phoenix project manager from the Jet Propulsion Laboratory explained in previewing the descent.

2348 GMT (7:48 p.m. EDT)

A signal from Phoenix is continuing to be received via the Odyssey spacecraft.

2347 GMT (7:47 p.m. EDT)

Phoenix is encased within the descent system's aeroshell that looks like a saucer. Protecting the spacecraft from the intense temperatures of entry is a special cork material on the heat shield. The peak heating is expected to be 2,600 degrees F at an altitude of 26 miles. Yet inside the aeroshell, the lander will feel heat no greater than room temperature.

The peak deceleration should be 9.2 G's.

2346 GMT (7:46 p.m. EDT)

Entry begins. Soaring 78 miles above Mars at a speed of nearly 12,750 miles per hour, the Phoenix spacecraft has hit the top of the martian atmosphere to begin "seven minutes of terror." The friction of flying through the atmosphere will be used to slow the spacecraft significantly.

2342 GMT (7:42 p.m. EDT)

Eleven minutes from touchdown. The spacecraft is about 330 miles above Mars.

2341 GMT (7:41 p.m. EDT)

With the cruise stage and its solar arrays now discarded, Phoenix is relying on its internal batteries until after getting on the surface and deploying its own power-generating solar wings.

2340 GMT (7:40 p.m. EDT)

The turn to the entry orientation has begun.

2339 GMT (7:39 p.m. EDT)

Cruise stage separation. The descent module containing the Phoenix lander has been released from the cruise stage structure that held the solar arrays and other gear needed during the 10-month journey from Earth to Mars.

The landing system will now begin a 90-second maneuver to position the heat shield in the forward direction in preparation for entering the martian atmosphere about seven minutes from now.

2339 GMT (7:39 p.m. EDT)

The spacecraft is now 700 miles above the planet.

2338 GMT (7:38 p.m. EDT)

Phoenix should be on the surface in 15 minutes.

2335 GMT (7:35 p.m. EDT)

The Odyssey orbiter has loaded the onboard sequence for receiving the communications from Phoenix.

2328 GMT (7:28 p.m. EDT)

Final navigational readings are being taken from star tracker as a baseline calibration for the spacecraft's inertial measurement unit. The star tracker is then turned off.

2321 GMT (7:21 p.m. EDT)

And Mars Odyssey is now verified in the proper pointing attitude to serve as a live communications relay during the Phoenix entry.

2318 GMT (7:18 p.m. EDT)

Telemetry from the spacecraft confirms that pressurization of the Phoenix propulsion system is underway now.

2314 GMT (7:14 p.m. EDT)

The Mars Reconaissance Orbiter has completed its turn to the proper attitude for receiving ultra-high frequency communications from Phoenix during entry. MRO will record those communications for later playback to Earth.

2300 GMT (7:00 p.m. EDT)

Heaters on the spacecraft maneuvering jets have been turned on. These will heat the thrusters in preparation for their use to turn the spacecraft to the entry orientation.

2253 GMT (6:53 p.m. EDT)

Now one hour from the anticipated touchdown of Phoenix. The lander is bound for Mars to examine the frozen water in the northern plains that could be a habitable zone for life.

2216 GMT (6:16 p.m. EDT)

The Mars Odyssey and the Mars Reconnaissance Orbiter circling the red planet are confirmed in the proper configuration to provide communications support during today's entry, descent and landing of Phoenix.

2130 GMT (5:30 p.m. EDT)

Quickly picking up speed as Mars' gravity tightens its grip, NASA's Phoenix lander is hurtling toward the red planet for a nerve-wracking seven-minute parachute- and rocket-powered descent to the surface to dig for buried ice and clues about the habitability of the martian polar environment. Touchdown is expected at 7:53 p.m. EDT.

Read our full story.

2100 GMT (5:00 p.m. EDT)

The 92nd running of the Indianapolis 500 just ended. At the speed Phoenix will be traveling when it hits the atmosphere of Mars today, the spacecraft could cover the 500 miles in 2 minutes and 22 seconds. It took New Zealander Scott Dixon nearly four hours to drive the Indy 500 and claim the checkered flag.

1915 GMT (3:15 p.m. EDT)

The Phoenix has started feeling the pull of martian gravity today as the spacecraft nears the red planet. At 11:30 a.m. EDT, the craft's speed relative the Mars was 6,300 mph. That velocity is increasing as Phoenix gets closer to the planet, now over 8,000 mph, and will reach 12,700 mph when the atmospheric entry begins in a little more than four hours.

The descent using atmospheric friction, followed by a parachute and then rocket thrusters will remove that immense speed in just seven minutes for touchdown at 5 mph.

From the current position, Mars now appears to Phoenix some 10 times the size of a full moon as viewed from Earth. It has been 296 days since launch, a trek that has spanned 422 million miles.

"The sky is clear. We've been watching the weather. Everything is set for us. (We) have a sunny day," said Peter Smith, the Phoenix principal investigator from the University of Arizona-Tucson.

Flight controllers on Earth have finished sending commands to the spacecraft. Phoenix is operating on the stored program that will guide the lander to the surface.

"We have nothing else to do but watch," said Barry Goldstein, Phoenix project manager from the Jet Propulsion Laboratory.

Phoenix is headed for the arctic northern plains of Mars where it will touch down using small rocket engines similar to the Viking spacecraft 30 years ago. Equipped with an 8-foot robotic arm, Phoenix will dig up samples of the surrounding soil and water ice for examination within instruments on the lander's science deck.

1425 GMT (10:25 a.m. EDT)

The final opportunity to adjust the flight path of Phoenix will not be needed, officials concluded this morning. There had been a window available to perform one last course correction maneuver about 8 hours before landing.

0345 GMT (11:45 p.m. EDT Sat.)

NASA's Phoenix lander closed in on Mars Saturday, healthy and on course for touchdown Sunday evening near the red planet's northern polar cap. Engineers at the Jet Propulsion Laboratory in Pasadena, Calif., decided to forego a course-correction rocket firing late Saturday but left open the option for a final trajectory tweak Sunday eight hours before atmospheric entry.

Read our full story.

0114 GMT (9:14 p.m. EDT Sat.)

A course-correction maneuver by the Phoenix spacecraft will not be performed tonight, officials have decided.

"Phoenix is so well on course for its Sunday-evening landing on an arctic Martian plain that the team decided it was not necessary to do a trajectory correction 21 hours before landing," NASA said in a statement announcing the decision to skip the maneuver.

"However, the team left open the option of a correction maneuver eight hours before landing, if warranted by updated navigational information expected in the intervening hours."

SATURDAY, MAY 24, 2008
2130 GMT (5:30 p.m. EDT)

Maps illustrating the landing zone and the desired region that will determine whether or not a trajectory correction will be required tonight are posted here.

1940 GMT (3:40 p.m. EDT)

Mission managers will decide no later than 8:30 p.m. EDT whether Phoenix needs to perform a tiny maneuver tonight that would move its landing site target and lessen the odds of the craft coming down in a rocky area. Final trajectory analysis underway this afternoon will culminate with officials determining if the course-correction is necessary.

Phoenix has performed four maneuvers to change its flight path since launch. Tonight's would be a very brief maneuver, similar to pressing a spray can for a few moments. The result would move the target landing spot about six miles downtrack, officials said.

Phoenix remains in good shape and the landing zone weather appears favorable.

1530 GMT (11:30 a.m. EDT)

Phoenix continues to streak toward its rendezvous with Mars. As of 11 a.m. EDT this morning, the spacecraft had 1.46 million miles remaining on its 422-million-mile flight from Earth to Mars. Phoenix was launched from Cape Canaveral aboard a Delta 2 rocket last August 4. Landing tomorrow night is expected at 7:53 p.m. EDT.

FRIDAY, MAY 23, 2008

The Phoenix spacecraft is just a couple million miles from its destination for Sunday's landing on the northern plains of Mars.

"All systems are nominal and stable," said Ed Sedivy, Phoenix spacecraft program manager for Lockheed Martin Space Systems, of Denver, which built the spacecraft. "We have plenty of propellant, the temperatures look good and the batteries are fully charged."

Tracking information shows Phoenix is on course toward its planning landing zone.

"The latest calculation from our navigation team shows the center of the area where we're currently headed lies less than eight miles from the center of our target area," said Barry Goldstein, Phoenix project manager at NASA's Jet Propulsion Laboratory, located in Pasadena, Calif.

"We may decide on Saturday that we don't need to use our final opportunity for fine-tuning the trajectory Phoenix is on. Either way, we will continue to monitor the trajectory throughout Saturday night, on the off chance we need to execute our contingency maneuver eight hours before entry."

The martian weather outlook also appears favorable for the Phoenix arrival. Images from the Mars Reconnaissance Orbiter show no significant dust storms around the landing site.

Watch this page for live updates throughout Sunday evening's landing!

THURSDAY, MAY 22, 2008

This Sunday evening, 171 million miles beyond its builders' ability to do anything but watch and bite their nails as they monitor events that happened 15 minutes earlier, NASA's appropriately named Phoenix spacecraft will slam into the upper atmosphere of Mars at a blistering 12,527 mph some 77.6 miles above the red planet's frozen surface.

Read our landing preview story.

MONDAY, MAY 12, 2008

When NASA's Phoenix Mars Lander descends to the surface of the Red Planet on May 25, few will be watching as closely as the men and women who have spent years planning, analyzing and conducting tests to prepare for the dramatic and nerve-wracking event known as EDL -- Entry, Descent and Landing. For after all their hard work, they know that landing on Mars is not a walk in the park. Less than 50 percent of all previous lander missions have made it safely to the surface.

Like all missions, Phoenix was motivated by the potential science rewards. With its robotic arm, Phoenix will be the first mission to reach out and touch water ice in Mars' north polar region. The mission will study the history of the water in the ice, monitor weather of the polar region, and investigate whether the subsurface environment in the far-northern plains of Mars has ever been favorable for sustaining microbial life.

Much of the Phoenix spacecraft already sat in secure storage when, in 2003, NASA selected it over other proposals to fly to Mars. Phoenix's main systems were designed and built for launch as the Mars Surveyor 2001 Lander, but that mission was canceled in February 2000, after the loss of a similar spacecraft, the Mars Polar Lander, during its arrival at Mars in 1999.

Read the full story .

See our earlier status center coverage.