BY JUSTIN RAY
FRIDAY, MAY 30, 2008
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."
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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
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."
"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.
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WEDNESDAY, MAY 28, 2008
"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.
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"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.
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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.
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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.
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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.
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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
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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.
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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."
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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.
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Parachute deployment appeared to be about 7 seconds later than predicted. Trajectory information looked normal.
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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.
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"I'm in shock. We had all the signals. Everything."
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The next communications pass will confirm the arrays are unfurled and possibly return the first pictures taken by Phoenix.
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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.
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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.
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The peak deceleration should be 9.2 G's.
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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.
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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.
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"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
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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.
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FRIDAY, MAY 23, 2008
"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
Read our landing preview story.
MONDAY, MAY 12, 2008
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.
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See our earlier status center coverage.
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