posted 01-26-2010 12:08 PM               

Now a Stationary Research Platform, NASA's Mars Rover Spirit Starts a New Chapter in Red Planet Scientific Studies

After six years of unprecedented exploration of the Red Planet, NASA's Mars Exploration Rover Spirit no longer will be a fully mobile robot. NASA has designated the once-roving scientific explorer a stationary science platform after efforts during the past several months to free it from a sand trap have been unsuccessful.

The venerable robot's primary task in the next few weeks will be to position itself to combat the severe Martian winter. If Spirit survives, it will continue conducting significant new science from its final location. The rover's mission could continue for several months to years.

"Spirit is not dead; it has just entered another phase of its long life," said Doug McCuistion, director of the Mars Exploration Program at NASA Headquarters in Washington. "We told the world last year that attempts to set the beloved robot free may not be successful. It looks like Spirit's current location on Mars will be its final resting place."

After six years on the move, Spirit prepares for a new phase of science

Ten months ago, as Spirit was driving south beside the western edge of a low plateau called Home Plate, its wheels broke through a crusty surface and churned into soft sand hidden underneath.

After Spirit became embedded, the rover team crafted plans for trying to get the six-wheeled vehicle free using its five functioning wheels -the sixth wheel quit working in 2006, limiting Spirit's mobility. The planning included experiments with a test rover in a sandbox at NASA's Jet Propulsion Laboratory in Pasadena, Calif., plus analysis, modeling and reviews. In November, another wheel quit working, making a difficult situation even worse.

Recent drives have yielded the best results since Spirit became embedded. However, the coming winter mandates a change in strategy. It is mid-autumn at the solar-powered robot's home on Mars. Winter will begin in May. Solar energy is declining and expected to become insufficient to power further driving by mid-February. The rover team plans to use those remaining potential drives for improving the rover's tilt. Spirit currently tilts slightly toward the south. The winter sun stays in the northern sky, so decreasing the southward tilt would boost the amount of sunshine on the rover's solar panels.

"We need to lift the rear of the rover, or the left side of the rover, or both," said Ashley Stroupe, a rover driver at JPL. "Lifting the rear wheels out of their ruts by driving backward and slightly uphill will help. If necessary, we can try to lower the front right of the rover by attempting to drop the right-front wheel into a rut or dig it into a hole."

At its current angle, Spirit probably would not have enough power to keep communicating with Earth through the Martian winter. Even a few degrees of improvement in tilt might make enough difference to enable communication every few days.

"Getting through the winter will all come down to temperature and how cold the rover electronics will get," said John Callas, project manager at JPL for Spirit and its twin rover, Opportunity. "Every bit of energy produced by Spirit's solar arrays will go into keeping the rover's critical electronics warm, either by having the electronics on or by turning on essential heaters."

After six years on the move, Spirit prepares for a new phase of science

Even in a stationary state, Spirit continues scientific research.

"There's a class of science we can do only with a stationary vehicle that we had put off during the years of driving," said Steve Squyres, a researcher at Cornell University and principal investigator for Spirit and Opportunity. "Degraded mobility does not mean the mission ends abruptly. Instead, it lets us transition to stationary science."

One stationary experiment Spirit has begun studies tiny wobbles in the rotation of Mars to gain insight about the planet's core. This requires months of radio-tracking the motion of a point on the surface of Mars to calculate long-term motion with an accuracy of a few inches.

"If the final scientific feather in Spirit's cap is determining whether the core of Mars is liquid or solid, that would be wonderful -- it's so different from the other knowledge we've gained from Spirit," said Squyres.

Tools on Spirit's robotic arm can study variations in the composition of nearby soil, which has been affected by water. Stationary science also includes watching how wind moves soil particles and monitoring the Martian atmosphere.

Spirit and Opportunity landed on Mars in January 2004. They have been exploring for six years, far surpassing their original 90-day mission. Opportunity currently is driving toward a large crater called Endeavor and continues to make scientific discoveries. It has driven approximately 12 miles and returned more than 133,000 images.

posted 01-26-2010 01:37 PM            

After six years of unprecedented exploration of the Red Planet, NASA's Mars Exploration Rover Spirit no longer will be a fully mobile robot. NASA has designated the once-roving scientific explorer a stationary science platform...

posted 02-12-2010 09:04 PM               

Spirit Finishes Pre-Winter Drives

NASA's Mars Exploration Rover Spirit is now parked for the winter. The rover team is commanding Spirit this week to make additional preparations for the Mars southern hemisphere winter season. The team does not plan further motion of the wheels until spring comes to Spirit's location beside the western edge of a low plateau called Home Plate.

On Sol 2169 (Feb. 8, 2010), the rover's last drive before winter changed the angles of its suspension system, but it did not produce a hoped-for improvement to the overall tilt of the solar array for catching winter sunshine. Drives since Sol 2145 (Jan. 15, 2010) moved Spirit 34 centimeters (13 inches) south-southeastward. However, a counterclockwise yawing of the rover during the drives prevented it from reducing its southerly tilt.

Spirit will spend the coming winter tilted 9 degrees toward the south, an unfavorable attitude for the solar panels to catch rays from the sun in the northern sky. Spirit's parking positions for its previous three Martian winters tilted northward. Engineers anticipate that, due to the unfavorable tilt for this fourth winter, Spirit will be out of communication with Earth for several months.

Spirit may enter a low-power hibernation mode within a few weeks, shutting down almost all functions except keeping a master clock running and checking its power status periodically until it has enough power to reawaken. It may go in and out of this mode a few times at the beginning and at the end of an extended hibernation period.

This week the rover team is uploading schedules to Spirit for when to communicate with Earth or with the orbiting Mars Odyssey during the rest of this year and into 2011. Spirit will use these schedules whenever it has adequate power to wake up. Spirit will take a set of "before" images of surroundings from the parked position this week, for comparison with images in the Martian spring to study effects of wind. Images toward the south will also aid preparations for possible future drives, although, with only four of its six wheels still working, the rover is not expected to move farther than short repositioning drives. Other preparations for winter will include putting the robotic arm into a position for studies of atmospheric composition when power is available and changing the stow positions of the high-gain antenna and panoramic camera to minimize shadowing of the solar panels.

Spirit is more than six years into a mission originally planned for three months on Mars. Its twin, Opportunity, is exploring an area halfway around the planet and closer to the equator, where that rover does not need to park for the winter.

posted 03-24-2010 10:19 PM               

sols 2200-2203, March 12-15, 2010: Spirit Electronics Getting Colder

In her winter position, still embedded in the area called "Troy" on the west side of Home Plate, Spirit has transitioned to executing a single, seven-sol plan each week, as long as power permits.

The seven-sol plan contains a single X-band uplink and a single Ultra-High Frequency (UHF) downlink. The activity on each sol consists simply of a brief wakeup, an atmospheric opacity (tau) measurement, and then a shutdown for the rest of the day and night.

The last downlink from the rover was on Sol 2203 (March 15, 2010). From that downlink, Spirit was still under master sequence control and all systems were green. Energy production was down to 139 watt-hours per sol. Battery state of charge did not decrease significantly, suggesting that Spirit was able to stay roughly power neutral over the last few sols. Solar array energy production levels will continue to drop and rover heating requirements will continue to increase, leading to widening energy deficits.

The solid-state power amplifier (SSPA), as a proxy for the rover electronics module (REM), reached a record low temperature of minus 41 degrees Celsius (minus 41.8 degrees Fahrenheit). Spirit is getting colder than ever before. The plan for this week is to sequence another seven-sol plan to be uplinked this Friday with a single UHF downlink over the weekend. Spirit could enter low-power fault at anytime and become quiet for an extended period of time to charge her batteries.

As of Sol 2203 (March 15, 2010), the rover solar array energy production was to 139 watt-hours with an atmospheric opacity (tau) of 0.379 measured on Sol 2202 (March 14, 2010), and a dust factor of 0.507. Total odometry is unchanged at 7,730.50 meters (4.80 miles).

posted 04-30-2010 10:49 AM               

30 year record broken? When Spirit comes out of hibernation, she can claim Viking 1's record for longest-lived surface mission.

Opportunity, still driving, hopes to break the Viking 1 record too. Opportunity will hit that mark (2,245 days!) on May 20.

posted 05-08-2010 08:03 AM               

quote:

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Originally posted by Philip:
I wonder if there's still good use (weather station?) for a stuck rover...

---

"There's a class of science we can do only with a stationary vehicle that we had put off during the years of driving," said Steve Squyres, a researcher at Cornell University and principal investigator for Spirit and Opportunity. "Degraded mobility does not mean the mission ends abruptly. Instead, it lets us transition to stationary science."

One stationary experiment Spirit has begun studies tiny wobbles in the rotation of Mars to gain insight about the planet's core. This requires months of radio-tracking the motion of a point on the surface of Mars to calculate long-term motion with an accuracy of a few inches.

"If the final scientific feather in Spirit's cap is determining whether the core of Mars is liquid or solid, that would be wonderful -- it's so different from the other knowledge we've gained from Spirit," said Squyres.

posted 06-03-2010 03:20 PM               

NASA Rover Finds Clue To Mars' Past And Environment For Life

Rocks examined by NASA's Spirit Mars Rover hold evidence of a wet, non-acidic ancient environment that may have been favorable for life. Confirming this mineral clue took four years of analysis by several scientists.

An outcrop that Spirit examined in late 2005 revealed high concentrations of carbonate, which originates in wet, near-neutral conditions, but dissolves in acid. The ancient water indicated by this find was not acidic.

NASA's rovers have found other evidence of formerly wet Martian environments. However the data for those environments indicate conditions that may have been acidic. In other cases, the conditions were definitely acidic, and therefore less favorable as habitats for life.

Laboratory tests helped confirm the carbonate identification. The findings were published online Thursday, June 3 by the journal Science.

"This is one of the most significant findings by the rovers," said Steve Squyres of Cornell University in Ithaca, N.Y. Squyres is principal investigator for the Mars twin rovers, Spirit and Opportunity, and a co-author of the new report. "A substantial carbonate deposit in a Mars outcrop tells us that conditions that could have been quite favorable for life were present at one time in that place. "

Spirit inspected rock outcrops, including one scientists called Comanche, along the rover's route from the top of Husband Hill to the vicinity of the Home Plate plateau which Spirit has studied since 2006. Magnesium iron carbonate makes up about one-fourth of the measured volume in Comanche. That is a tenfold higher concentration than any previously identified for carbonate in a Martian rock.

"We used detective work combining results from three spectrometers to lock this down," said Dick Morris, lead author of the report and a member of a rover science team at NASA's Johnson Space Center in Houston."The instruments gave us multiple, interlocking ways of confirming the magnesium iron carbonate, with a good handle on how much there is."

Massive carbonate deposits on Mars have been sought for years without much success. Numerous channels apparently carved by flows of liquid water on ancient Mars suggest the planet was formerly warmer, thanks to greenhouse warming from a thicker atmosphere than exists now. The ancient, dense Martian atmosphere was probably rich in carbon dioxide, because that gas makes up nearly all the modern, very thin atmosphere.

It is important to determine where most of the carbon dioxide went. Some theorize it departed to space. Others hypothesize that it left the atmosphere by the mixing of carbon dioxide with water under conditions that led to forming carbonate minerals. That possibility, plus finding small amounts of carbonate in meteorites that originated from Mars, led to expectations in the 1990s that carbonate would be abundant on Mars. However, mineral-mapping spectrometers on orbiters since then have found evidence of localized carbonate deposits in only one area, plus small amounts distributed globally in Martian dust.

Morris suspected iron-bearing carbonate at Comanche years ago from inspection of the rock with Spirit's Moessbauer Spectrometer, which provides information about iron-containing minerals. Confirming evidence from other instruments emerged slowly. The instrument with the best capability for detecting carbonates, the Miniature Thermal Emission Spectrometer, had its mirror contaminated with dust earlier in 2005, during a wind event that also cleaned Spirit's solar panels.

"It was like looking through dirty glasses," said Steve Ruff of Arizona State University in Tempe, Ariz., another co-author of the report. "We could tell there was something very different about Comanche compared with other outcrops we had seen, but we couldn't tell what it was until we developed a correction method to account for the dust on the mirror."

Spirit's Alpha Particle X-ray Spectrometer instrument detected a high concentration of light elements, a group including carbon and oxygen, that helped quantify the carbonate content.

The rovers landed on Mars in January 2004 for missions originally planned to last three months. Spirit has been out of communication since March 22 and is in a low-power hibernation status during Martian winter. Opportunity is making steady progress toward a large crater, Endeavour, which is about seven miles away.

posted 07-30-2010 12:40 PM               

NASA's Hibernating Mars Rover May Not Call Home

ASA mission controllers have not heard from the Mars Exploration Rover Spirit since March 22, and the rover is facing its toughest challenge yet -- trying to survive the harsh Martian winter.

The rover team anticipated Spirit would go into a low-power "hibernation" mode since the rover was not able to get to a favorable slope for its fourth Martian winter, which runs from May through November. The low angle of sunlight during these months limits the power generated from the rover's solar panels. During hibernation, the rover suspends communications and other activities so available energy can be used to recharge and heat batteries, and to keep the mission clock running.

On July 26, mission managers began using a paging technique called "sweep and beep" in an effort to communicate with Spirit.

"Instead of just listening, we send commands to the rover to respond back to us with a communications beep," said John Callas, project manager for Spirit and Opportunity at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "If the rover is awake and hears us, she will send us that beep."

Based on models of Mars' weather and its effect on available power, mission managers believe that if Spirit responds, it most likely will be in the next few months. However, there is a very distinct possibility Spirit may never respond.

"It will be the miracle from Mars if our beloved rover phones home," said Doug McCuistion, director of NASA's Mars Exploration Program in Washington. "It's never faced this type of severe condition before -- this is unknown territory."

Because most of the rover's heaters were not being powered this winter, Spirit is likely experiencing its coldest internal temperatures yet -- minus 67 degrees Fahrenheit. During three previous Martian winters, Spirit communicated about once or twice a week with Earth and used its heaters to stay warm while parked on a sun-facing slope for the winter. As a result, the heaters were able to keep internal temperatures above minus 40 degrees Fahrenheit.

Spirit is designed to wake up from its hibernation and communicate with Earth when its battery charge is adequate. But if the batteries have lost too much power, Spirit's clock may stop and lose track of time. The rover could still reawaken, but it would not know the time of day, a situation called a "mission-clock fault." Spirit would start a new timer to wake up every four hours and listen for a signal from Earth for 20 minutes of every hour while the sun is up.

The earliest date the rover could generate enough power to send a beep to Earth was calculated to be around July 23. However, mission managers don't anticipate the batteries will charge adequately until late September to mid-October. It may be even later if the rover is in a mission-clock fault mode. If Spirit does wake up, mission managers will do a complete health check on the rover's instruments and electronics.

Based on previous Martian winters, the rover team anticipates the increasing haziness in the sky over Spirit will offset longer daylight for the next two months. The amount of solar energy available to Spirit then will increase until the southern Mars summer solstice in March 2011. If we haven't heard from it by March, it is unlikely that we will ever hear from it.

"This has been a long winter for Spirit, and a long wait for us," said Steve Squyres, the principal investigator for NASA's two rovers who is based at Cornell University. "Even if we never heard from Spirit again, I think her scientific legacy would be secure. But we're hopeful we will hear from her, and we're eager to get back to doing science with two rovers again."

posted 01-05-2011 04:17 PM               

NASA Checking on Rover Spirit During Martian Spring

Nine months after last hearing from the Mars rover Spirit, NASA is stepping up efforts to regain communications with the rover before spring ends on southern Mars in mid-March.

Spirit landed on Mars Jan. 4, 2004 (Universal Time; Jan. 3, Pacific Time) for a mission designed to last for three months. After accomplishing its prime-mission goals, Spirit worked for more than five years in bonus-time extended missions.

"The amount of solar energy available for Spirit is still increasing every day for the next few months," said Mars Exploration Rover Project Manager John Callas of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "As long as that's the case, we will do all we can to increase the chances of hearing from the rover again."

After mid-March, prospects for reviving Spirit would begin to drop. Communication strategies would change based on reasoning that Spirit's silence is due to factors beyond just a low-power condition. Mission-ending damage from the cold experienced by Spirit in the past Martian winter is a real possibility.

The rover's motors worked far beyond their design life, but eventually, Spirit lost use of drive motors on two of its six wheels. This left it unable to obtain a favorable tilt for solar energy during the rover's fourth Martian winter, which began last May.

Spirit and its twin, Opportunity, which landed three weeks after Spirit and is still active, both have made important discoveries about wet environments on ancient Mars that may have been favorable for supporting microbial life.

Spirit last communicated on March 22, 2010. The rover team had anticipated that the rover would enter a low-power fault mode with minimal activity except charging and heating the batteries and keeping its clock running. With most heaters shut off, Spirit's internal temperatures dipped lower than ever before on Mars. That stress could have caused damage, such as impaired electrical connections, that would prevent reawakening or, even if Spirit returns to operation, would reduce its capabilities.

Southern-Mars spring began in November 2010. Even before that, NASA's Deep Space Network of antennas in California, Spain and Australia has been listening for Spirit daily. The rover team has also been sending commands to elicit a response from the rover even if the rover has lost track of time.

Now, the monitoring is being increased. Additional listening periods include times when Spirit might mistake a signal from NASA's Mars Reconnaissance Orbiter as a signal from Earth and respond to such a signal. Commands for a beep from Spirit will be sent at additional times to cover a wider range of times-of-day on Mars when Spirit might awaken. Also, NASA is listening on a wider range of frequencies to cover more possibilities of temperature effects on Spirit's radio systems.