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Spirit (rover)

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Spirit (official designation: MER-A) is the first of the two Mars Exploration Rover missions. She successfully landed on Mars at 04:35 Ground UTC on January 4, 2004 and has operated successfully for over one full Martian year or two Earth years. Her twin Opportunity landed successfully on Mars on January 24, 2004. (Mission members decided to reference both rovers using the feminine gender.) Spirit was named by a winning entry in a student essay competition—see Naming of Spirit and Opportunity.

File:NASA Mars Exploration Rover.jpg
Artist's Concept of Rover on Mars (credit: Maas Digital LLC) (3D version)

Landing site: Columbia Memorial Station

Rover tracks on sol 85 from Mars Global Surveyor

Spirit landed in Gusev crater about 10 km from the center of the target ellipse at latitude 14.5718° S ± 30 meters, longitude 175.4785° E ± 0.5 meters [1].

A panorama [2] shows a slightly rolling surface, littered with small rocks, with hills on the horizon up to 27 km away. The MER team named the landing site "Columbia Memorial Station," in honor of the seven astronauts killed in the Space Shuttle Columbia disaster.

On January 27 NASA memorialized the crew of Apollo 1 by naming three hills to the north of "Columbia Memorial Station" as the Apollo 1 Hills. On February 2, the astronauts on Columbia's final mission were further memorialized when NASA named a set of hills to the east of the landing site the Columbia Hills Complex, denoting seven peaks in that area Anderson, Brown, Chawla, Clark, Husband, McCool and Ramon. (NASA has submitted these geographical feature names to the IAU for approval.)


File:55172main apollo hills.jpg
Apollo Hills panorama from the Spirit landing site

Events and discoveries

Timeline

Current Spirit traverse map, to sol 715 (January 6, 2006)

The primary surface mission for Spirit was planned to last 90 sols. The mission received several extensions and as of March 20, 2006 had passed 786 sols.

A detailed but incomplete chronology of events and discoveries may be found in the Spirit rover timeline entry. The following paragraphs discuss the more notable findings.

An archive of approximately weekly updates on the rover's status can be found at Spirit Update Archive (NASA/JPL site).

Sleepy Hollow

"Sleepy Hollow," a shallow depression in the Mars ground near NASA's Spirit rover, was targeted as an early destination when the rover drove off its lander platform. NASA scientists were very interested in this crater. It is 9 meters (30 feet) across and about 12 meters (40 feet) north of the lander.

First 3-D panorama of landing site: the crater under the sun is "Sleepy Hollow" received on 5 January. 3D red cyan glasses are recommended to view this image correctly.

"Just as the ancient mariners used sextants for 'shooting the Sun,' as they called it, we were successfully able to shoot the Sun with our panorama camera, then use that information to point the antenna," said JPL's Matt Wallace, mission manger.

First color photograph

Part of the first color photograph sent. "Sleepy Hollow" is visible at the right of this photograph

To the right is the first color image of Mars taken by the panoramic camera on the Mars Exploration Rover Spirit. It is the highest resolution image ever taken on the surface of another planet. "We're seeing a panoramic mosaic of four pancam images high by three wide," said camera designer Jim Bell of Cornell. There are actually 12 million pixels in this image, it's 4,000 high by 3,000 wide. This, however, is only the tip of the iceberg, as this image, received on 6 January 2004, is about one eighth of a single pancam panorama and isn't stereo.

January 21 flash memory management anomaly

On 21 January (Sol 18), Spirit abruptly ceased communicating with mission control. The next day the rover radioed a 7.8 bit/s beep, confirming that it had received a transmission from Earth but indicating that the spacecraft believed it was in a fault mode. This was described as a very serious anomaly, but potentially recoverable if it was a software or memory corruption issue rather than a serious hardware failure. Spirit was commanded to transmit engineering data, and on 23 January sent several short low-bitrate messages before finally transmitting 73 megabits via X band to Mars Odyssey. This suggested difficulties with the rover's high-gain antenna. The rover had also been in a processor reset loop of some type since Wednesday, in which the processor would repeatedly wake, load the flight software, and uncover a condition that would cause it to reset. The processor was not resetting immediately, however, with a delay of up to an hour. Indications were that the cause of the reset was not always perceived by the rover's diagnostics to be the same each time.

On 24 January the rover repair team announced that the problem was with Spirit's flash memory and the software that wrote to it. Spirit was placed in "crippled mode," operating using RAM instead of flash. In this mode, the rover obeyed commands about communicating and going into sleep mode. Spirit communicated successfully at 120 bits per second for nearly an hour. The flash hardware was in fact believed to be working correctly but the file management module in the software was "not robust enough" for the operations the Spirit was engaged in when the problem occurred, indicating that the problem was caused by a software bug as opposed to faulty hardware.

The engineers indicated that they had initially believed that this was a serious problem, and as a result, performed operations that only exacerbated the minor situation. NASA engineers finally came to the conclusion that there were too many files on the filesystem, which was a relatively minor problem. Most of these files contained unneeded in-flight data. After realizing what the problem was, the engineers deleted some files, and eventually reformatted the entire flash memory system. On 6 February (Sol 33), the rover was restored to its original working condition, and science activities resumed.

History's first grinding of a rock on Mars

Pancam image of Adriondack taken after RAT grind.

The round, shallow depression in this image resulted from history's first grinding of a rock on Mars. The Rock Abrasion Tool on NASA's Spirit rover ground off the surface of a patch 45.5 millimeters (1.8 inches) in diameter on a rock called Adirondack during Spirit's 34th sol on Mars, Feb. 6, 2004. The hole is 2.65 millimeters (0.1 inch) deep, exposing fresh interior material of the rock for close inspection with the rover's microscopic imager and two spectrometers on the robotic arm. This image was taken by Spirit's panoramic camera, providing a quick visual check of the success of the grinding. The rock abrasion tools on both Mars Exploration Rovers were supplied by Honeybee Robotics, New York, N.Y.

"The RAT performed beyond our expectations," beamed Steve Gorevan, of Honeybee Robotics, New York, lead scientist for the rock abrasion tools on both rovers. "With the docile cutting parameters we set, I didn't think that it would cut this deep. In fact, when we saw virtually a complete circle, I was thrilled beyond anything I could have ever dreamed. Following up that glorious circular brushing — it's like back-to-back homers."

Mimi

False color image of "Mimi".

This color image taken by the Mars Exploration Rover Spirit's panoramic camera on Sol 40 is centered on an unusually flaky rock called Mimi. Mimi is only one of many features in the area known as "Stone Council", but looks very different from any rock that scientists have seen at the Gusev crater site so far. Mimi's flaky appearance leads scientists to a number of hypotheses. Mimi could have been subjected to pressure either through burial or impact, or may have once been a dune that was cemented into flaky layers, a process that sometimes involves the action of water.

Humphrey and clues for water

On March 5, 2004, NASA announced that Spirit had found hints of water history on Mars in a rock dubbed "Humphrey". Dr. Ray Arvidson of Washington University, St. Louis, reported during a NASA press conference: "If we found this rock on Earth, we would say it is a volcanic rock that had a little fluid moving through it." In contrast to the rocks found by the twin rover Opportunity, this one was formed from magma and then acquired bright material in small crevices, which look like crystallized minerals. If this interpretation holds true, the minerals were most likely dissolved in water, which was either carried inside the rock or interacted with it at a later stage, after it formed. (Press release)

Bonneville Crater

On 11 March 2004, the Spirit rover reached Bonneville crater after a 400 yard journey. This crater is 150 yards across and about 30 yards deep. JPL decided that it would be a bad idea to send the rover down into the crater, as they saw no targets of interest inside. Spirit drove along the southern rim, tore up some sand dunes, and continued to the southwest towards the Columbia Hills.

  • Looking back at the lander.
    Looking back at the lander.
  • Bonneville Crater.
    Bonneville Crater.

Missoula and Lahonten Craters, en route to Columbia Hills

Missoula Crater
Lahonten crater on Sol 120

Spirit reached Missoula crater on Sol 105. The crater is roughly 100 yards across and 20 yards deep. Missoula crater was not considered a high priority target due to the older rocks it contained. The rover skirted the northern rim, and continued to the southeast.

It then reached Lahonten crater on Sol 118, and drove along the rim until Sol 120. Lahonten is about 60 yards across and about 10 yards deep. A long, snaking sand dune stretches away from its southwestern side, and Spirit went around it.

Columbia Hills

On Sol 159, Spirit reached the first of many targets at the base of the Columbia Hills called West Spur. Hank's Hollow was studied for 23 sols. Within Hank's Hollow was the strange looking rock dubbed "Pot of Gold".

From here, Spirit took a northernly path along the base of the hill towards the target Wooly Patch, which was studied from Sol 192 to Sol 199. By Sol 203, Spirit had driven southward up the hill and arrived at the rock dubbed "Clovis". Clovis was ground and analyzed from Sol 210 to Sol 225. Following Clovis came the targets of Ebenezer (Sols 226-235), Tetl (Sol 270), Uchben and Palinque (Sols 281-295), and Lutefisk (Sols 296-303). From Sols 239 to 262, Spirit powered down for solar conjunction.

Slowly, Spirit has made its way around the summit of Husband Hill, and at Sol 344 was ready to climb over the newly designated "Cumberland Ridge" and into "Larry's Lookout" and "Tennessee Valley".

On Sol 371, Spirit arrived at a rock named "Peace" near the top of Cumberland Ridge. Spirit ground it with the RAT tool on Sol 373.

By Sol 390 (Mid-February 2005), Spirit was advancing towards "Larry's Lookout", by driving up the hill backwards in reverse. The scientists at this time were trying to conserve as much energy as possible for the climb.

Spirit also investigated some targets along the way, including the soil target, "Paso Robles", which contained the highest amount of salt found on the red planet. The soil also contained a high amount of phosphorus in its composition, however not nearly as high as another rock sampled by Spirit, "Wishstone". Squyres said of the discovery, "We're still trying to work out what this means, but clearly, with this much salt around, water had a hand here".

On 9 March 2005 (probably during the Martian night), the rover's solar panel efficiency jumped from around 60% of what it had originally been to 93%, followed on 10 March by the sighting of dust devils. NASA scientists speculate a dust devil must have swept the solar panels clean, possibly significantly extending the duration of the mission. This also marks the first time dust devils had been spotted by either Spirit or Opportunity, easily one of the top highlights of the mission to date. Dust devils had previously been photographed by only the Pathfinder probe.

  • Pot of Gold rock
    Pot of Gold rock
  • Spirit's traverse up Husband Hill
    Spirit's traverse up Husband Hill
  • Spirit artificially added to image (taken by itself) of Larry's Lookout
    Spirit artificially added to image (taken by itself) of Larry's Lookout
  • Photograph of a Martian sunset taken by Spirit at Gusev crater, May 19th, 2005.
    Photograph of a Martian sunset taken by Spirit at Gusev crater, May 19th, 2005.


Husband Hill summit

On Sol 582, August 21, 2005, Spirit reached the summit of Husband Hill and acquired a 360 degree panorama picture.

View from the Summit taken by Spirit on August 23, 2005 as the rover completed climb up "Husband Hill."


Home Plate

Spirit arrived at the north west corner of Home Plate, a raised and layered outcrop on sol 744 after an effort to maximize driving. Scientific observations have been conducted with Spirit's robotic arm.

McCool Hill

Spirit's next stop is the north face of McCool Hill, where Spirit should receive adequate sunlight during the Martian winter. As of sol 775 (March 9, 2006), Spirit's total odometry was 6,756 meters (4.2 miles). On March 16, 2006 JPL announced that Spirit's troublesome front wheel had stopped working altogether. Despite this, Spirit was still making progress toward McCool Hill because the control team programmed the rover to drive toward McCool Hill backwards, dragging its broken wheel.[3]


Astronomy

File:Photo of earth from mars.jpg
Earth from Mars

Spirit pointed its cameras towards the sky and observed a transit of the Sun by Mars' moon Deimos (see Transit of Deimos from Mars). It also took the only photo of Earth from another world in early March.

In fall of 2005 Spirit took advantage of a favorable energy situation to make multiple nighttime observations of both of Mars' moons Phobos and Deimos. These observations included a "lunar" (or rather phobal) eclipse as Spirit watched Phobos disappear into Mars's shadow. Some of Spirit's star gazing was designed to look for a predicted meteor shower caused by Halley's Comet but no images of meteors have been formally released.

A transit of Mercury from Mars took place on January 12 2005 from about 14:45 UTC to 23:05 UTC. Theoretically, this could have been observed by both Spirit and Opportunity, however camera resolution did not permit seeing Mercury's 6.1" angular diameter. They were able to observe transits of Deimos across the Sun, but at 2' angular diameter, Deimos is about 20 times larger than Mercury's 6.1" angular diameter. Ephemeris data generated by JPL Horizons indicates that Opportunity would have been able to observe the transit from the start until local sunset at about 19:23 UTC Earth time, while Spirit would have been able to observe it from local sunrise at about 19:38 UTC until the end of the transit.

Equipment failures

Both rovers passed the original mission time of 90 sols many times over but slowly problems did develop. By sol 415, Spirit's solar power generation was down 40 percent; however, a high wind later cleared dust of the panels, bringing them back to 93 percent. On sol 779, the right front wheel ceased working after having covered 4.2 miles on Mars. Engineers began driving the rover backwards, dragging the dead wheel. They have been in a race against the time, struggling to find the rover a suitable area to rest, where Spirit will have to collect enough solar energy as the sun sinks low for the mars winter.

Honors

Honoring Spirit's great contribution to the exploration of Mars, the asteroid 37452 has been named after it. The name was proposed by Ingrid van Houten-Groeneveld who along with Cornelis Johannes van Houten and Tom Gehrels discovered the asteroid on September 24, 1960.

See also

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