Spirit (space probe)

Spirit (MER-A)
Mars Rover Spirit (MER-A), artist's impression
NSSDC ID	2003-027A
Mission goal	Mars , Gusev crater
Client	NASA
Launcher	Delta II 7925
construction
Takeoff mass	1063 kg
Course of the mission
Start date	June 10, 2003, 17:58 UTC
launch pad	Cape Canaveral , LC-17A
End date	May 25, 2011 (lost connection)

Size comparison of a MER and the Sojourner rover

Launch of Spirit on a Delta II rocket

The landing site inside the Gusev crater , southwest of the Bonneville crater, which is the largest in the picture

Spirit ( English for spirit , soul ) is launched in June 2003 American spacecraft of NASA for exploration of the planet Mars . It was originally called Mars Exploration Rover A , MER-A for short , and was renamed Spirit after launch. Spirit landed in Gusev Crater on January 4, 2004 . The landing site is named "Columbia Memorial Station" in honor of the astronauts who died in the Columbia disaster .

Since March 22, 2010, no contact could be made with the probe. Since all attempts to contact Spirit were unsuccessful during the following year, NASA ended active contact with the rover on May 25, 2011, which corresponds to a de facto end of the mission.

The sister probe Opportunity (MER-B) landed on January 25, 2004 in the Meridiani Planum plain and was active until June 10, 2018.

mission

Spirit looked for traces of any previously existing water and geologically explored the landing site. The scientists involved around the world hoped to use the results to gain new knowledge about the history of the Martian climate. The Gusev crater was selected as a scientific target in a complicated process, as images of the space probes Mars Global Surveyor and 2001 Mars Odyssey reveals pronounced traces of a former lake.

From a technical point of view, landing in Gusev Crater was one of the most challenging, as very strong winds can occur in this region. However, after modifying the landing unit, the NASA engineers involved in the project gave the go-ahead for the mission. The landing unit determined based on three images that were taken shortly before landing and high-contrast features such as B. Crater evaluated the horizontal speed of the landing module. The horizontal direction and speed of movement determined in this way could later be reduced by a specially designed engine system. This made it possible to finally select the scientifically most important goal, the Gusev crater, as the landing site.

The mission duration should initially be a guaranteed 90 days, but Spirit has exceeded this by far. The mission was extended regularly. The rover has been stuck in the sand since April 2009. Until January 2010, attempts were unsuccessful to free him by driving maneuvers. On March 22, 2010 the last signals were picked up by Spirit. It was assumed that the rover was in a kind of deep sleep as it was Mars winter. In the hope that the rover would report back when the sun rises, a communication campaign lasting several months was started by NASA. Since all communication attempts were unsuccessful, the rover was abandoned by NASA on May 25, 2011.

In total, Spirit worked 2210 Martian days (sols) on the surface and covered 7730 m on the Martian surface. A total of 156,002 recordings were transmitted with the cameras (panorama and navigation cameras), of which 6315 recordings were made with the microscope camera. 367 measurements were performed with the AXPS X-ray spectrometer and 932 measurements with the Mössbauer spectrometer .

Technology of the probe

The two rovers Spirit and Opportunity were identical. Therefore, a more detailed description of the technology can be found under Mars Exploration Rover .

In contrast to Mars Pathfinder , Spirit was not a fixed ground station, but a mobile robot called a "rover". It was 1.6 m long, up to 1.5 m high and weighed 185 kg. According to the specification, it should be able to cover around 100 m, a total of around 3 km, per day, depending on the nature of the surface, and remain operational on the planet's surface for up to six months. This exceeded the capabilities of its predecessor Sojourner on the Mars Pathfinder mission in 1997 about a factor of 60. The rover was even by NASA as "robotic geologist" (robotic geologist) called and had six independently driven wheels on stilts shaped telescopic legs. In addition to various he wore panoramic - (Pancam), navigation - (navcam) and hazard detection cameras (hazcams - hazard recognition cameras) a pivotable arm with a rock microscope (also with camera), a plurality of spectrometers ( Mößbauer , alpha particles , infrared ) and a mechanical tool that was able to brush off rock surfaces and drill several millimeters deep on a few square centimeters in order to be able to examine the inside of accessible rocks (rat - rock-abrasion-tool). The wheels are moved individually and are not only used for locomotion, but can also be used as scrapers to dig up the ground and thus examine a few centimeters of the soil profile mechanically and photographically. The rover had rechargeable batteries via solar panels and was put to sleep before sunset to save energy and "woken up" again by a radio signal after sunrise. With the help of its antennas, the device was able to send images and measurement results either to the orbiting orbiters of NASA and ESA used as intermediate stations to earth or directly to earth and to receive commands from there. Due to the relatively long transit time of the signals from Earth (up to 20 minutes depending on the distance between the planets), the rover and its on-board computers had to be able to act autonomously to a certain extent.

Course of the mission

1st half of 2004 - primary mission

After a travel time of seven months and a distance of 487 million kilometers, the probe entered the atmosphere of Mars on January 4, 2004. It was initially slowed down in the atmosphere to the speed of sound, protected by a heat shield. Then a parachute unfolded with a rocket system attached to its lines above the probe that was supposed to compensate for horizontal movements in the atmosphere. Shortly before touchdown, protective airbags around the probe were suddenly inflated. The last few meters above the surface were then covered in free fall. After the lander came to rest, the airbags were deflated again. Spirit landed south of the Martian equator in Gusev Crater at 5:35 a.m. CET . Then Spirit sent the first high-resolution color images from Mars. The resolution of the images is three times higher than the resolution of the Mars Pathfinder images. They showed a desert-like landscape of red-brown sand and stones .

During the first few days, the NASA ground team tried to pull the remains of the airbag landing system developed by ILC Dover , which protected Spirit during the final phase of the landing, out of the way. These blocked the front ramp that the rover was supposed to use to exit the lander. In addition, the cable connections in the area of ​​the central wheels and anchors that secured the Spirit robot arm were loosened with small detonators. A total of 126 such detonators have been detonated since Spirit landed. Only then could Spirit stand up and unfold its front and rear wheels. The landing unit has a total of three ramps. As the airbags continued to block the front ramp, the rover turned 120 degrees clockwise to exit the lander via an evasive ramp facing north-west.

After leaving the landing unit, the rover covered a distance of three meters and explored the chemical and mineralogical conditions with the devices installed on the robot arm within two days. For the first time, the first pictures could be taken with a microscope on another planet.

The weather on Mars continued to play well. The temperatures fluctuated between minus 10 and minus 75 degrees Celsius during the Martian summer and the atmosphere was not clouded by any sandstorms .

The Gusev crater towards the southwest

East Hill Complex on the eastern horizon, later renamed Columbia Hills

The first stone to be examined was two meters away and was named Adirondack by NASA scientists . Spirit needed 30 minutes for this route, the actual travel time was only two minutes. The “Adirondack” stone was to be examined with a microscope and then with two instruments from Germany, the Mößbauer spectrometer from the Mainz physicist Göstar Klingelhöfer and the APXS ( Alpha Particle X-Ray Spectrometer ) from the Max Planck Institute for Chemistry Mainz .

On January 21st ( Sol 18) the NASA ground team in Pasadena suddenly lost contact with Spirit. The scientific and technical data could not be received in the scheduled time window. NASA initially blamed a storm over Australia for the radio silence . The next day, the probe sent a limited amount of data in response to a command from the control center. Based on this rudimentary data, it could be determined that Spirit's computer was constantly restarting, a total of around 130 times. The reason for the restart was that too many files were stored in the computer's file system, and storage areas that were essential for the rover to function were overwritten. After the rover was instructed to erase this data and restart the control computer, normal operations could resume on February 6th (Sol 33).

On the first scientific working day after the failure, Spirit brushed the surface of the Adirondack baptized stone over an area of ​​4.5 centimeters with a brush. For the first time in the history of unmanned space travel, a hole was drilled in a stone on another planet. The researchers hoped that the analysis of the 2.4 millimeter deep hole with a diameter of 45 millimeters would provide an indication of the geological composition of the stone.

Adirondack , Spirit's first object of investigation

The Sleepy Hollow with prints from the airbags

Historic first drilling on a stone on Mars

It turned out that the surrounding rocks were basaltic in nature and showed no influence of water. That is why the first long-term target selected by NASA was the Bonneville crater. There they hoped to gain access to deeper rock layers. Around the 90th Sol Spirit had reached this crater, but this seemed to be geologically completely uninteresting compared to the surroundings. It was therefore decided, despite its short service life of 90 days and a planned 600 m route, to send the rover to the Columbia Hills, more than 2 km away , which were the last hope of still encountering traces of water.

2nd half of 2004 - Columbia Hills

Spirit drove in a direct line from Bonneville Crater towards the Columbia Hills . The route was only precisely specified by the engineers on difficult terrain. Most of the time, however, the rover drove in autonomous mode. He reached the hill on Sol 158th after a distance of more than three kilometers. Some promising rocks have been discovered at the base of the Columbia Hills , including an unusually weathered rock called the Pot-of-Gold . It was difficult for Spirit to analyze this stone because, in contrast to the rocks examined so far, it was located in a rough and slippery terrain. After a detailed examination with the AXPS X-ray spectrometer and the Mössbauer spectrometer, it turned out that this stone contains hematite . This rock can form in connection with water, among other things.

As the energy produced by the solar panels continued to decrease due to the falling position of the sun and dust deposits, the so-called deep sleep mode was introduced (as with Opportunity). The rover is completely switched off during the night in order to save energy, also at the risk of instruments being damaged.

After a few driving tests, the climb to the Columbia Hills began on Sol 184 . The route was selected so that the Spirit solar cells are always oriented towards the sun as far as possible. In the meantime, the right front wheel was measured to have an increased current resistance. In order to relieve this bike, all further trips were made in reverse. At Sol 205, another unusual stone called Clovis was examined. In the spectrum recorded by the Mössbauer instrument, a clear signature of the iron-containing mineral goethite was found . Goethite contains water in the form of hydroxyl as part of its structure. This is considered to be one of the safest clues for water on the red planet, as goethite only forms in connection with water.

Spirit also led a number of successful communication tests with the probe Mars Express of the ESA by. Most communication continues to take place via NASA's Mars Odyssey and Mars Global Surveyor probes .

1st half of 2005 - ascent of the Husband Hills

Spirit had now been an earth year on Mars and drove slowly up the hill called Husband Hill . This turned out to be difficult as the path went through many rocky obstacles and sandy sections. This often led to the rover's wheels spinning and the intended distance not being driven.

In February the computer received a software update from Spirit in order to be able to operate even more autonomously.

Spirit in the Columbia Hills , artificially generated photo-realistic image

In addition, the amount of energy gained continued to decrease despite the increased inclination towards the sun, due to a relatively thick layer of dust on the solar panels in contrast to the sister probe Opportunity . In the meantime, Spirit observed an increased number of dust devils at this time of year , suggesting that it is very windy in Gusev Crater at this time of year. Around March 9, 2005, one of these dust devils hit the rover and freed the solar cells from the accumulated dust. The energy level rose to 800 watt hours per day. This gave Spirit almost twice as much energy as before this cleaning event .

The higher the rover went, the more scientifically interesting it seemed. On Sol 407, the ridge called Larry's Lookout was reached below the summit and panoramic photos of the area were taken. Nearby, Paso Robles rocks and the sand churned by Spirit's wheels were examined at the site . Light-colored, sulfur-containing material was identified with the AXPS X-ray spectrometer. In addition, the highest salt concentration ever measured on a rock or ground on Mars was measured here. With the information obtained from the other instruments, it was assumed that the main component is an iron sulfate salt with water molecules embedded in it.

2nd half of 2005 - Husband Hill Summit

Spirit's route from the landing site to the Columbia Hills

and display information about the image

Panorama of the Husband Hills

By August, Spirit was only 100 meters from the summit. It turned out that Husband Hill has two peaks, one of which is slightly higher than the other. On September 29th, 618th day of Mars, Spirit reached the real summit of Husband Hill. The rover was the first space probe to conquer a mountain on a strange celestial body. The total distance covered added up to 4973 meters. The summit itself was rather flat. Spirit took a 360 degree panorama in true colors from the summit, which included the entire Gusev crater. At night the rover observed the two Martian moons Phobos and Deimos in order to be able to determine their orbital parameters even more precisely. Attempts were also made to photograph meteors, as Mars was moving through the meteor shower of Comet Halley at that time.

At Sol 656, Spirit made observations of the Mars sky and atmospheric permeability using the panoramic camera to conduct coordinated research with the Hubble Space Telescope in Earth orbit.

From the summit, Spirit could already see a conspicuous formation, the home plate , in a valley . However, Spirit later had to continue to McCool Hill in order to be able to align its solar panels towards the sun in winter. So at the end of October he started the descent from Husband Hill and made his way to this valley, where he was to visit Home Plate and later this hill.

On the way down, Spirit reached a rock formation called Comanche on Sol 690. It turned out that this rock consists of around 16 to 34 percent magnesium-iron-carbonate. This mineral forms in wet and pH-neutral environments, but dissolves in acidic liquids. Here an important indication was found that non-acidic water must also have existed on Mars.

1st half of 2006 - drive to McCool Hill

Husband Hill's descent was rapid. On the way to home plate, Spirit passed a field of dunes called El Dorado .

Spirit had reached home plate on February 10th and determined that it was a cooled volcanic formation that showed a conspicuous layered structure. However, it was now winter time and it was decided to abort the investigation of home plate and to try to reach the north side of the McCool Hills with the rover in order to bring it into a favorable inclination to the sun during the coming Martian winter. Now, of all times, the right front wheel of the rover blocked, which had been behaving noticeably for a long time. From now on Spirit had to drag the defective wheel through the other five wheels, but this wheel acted like an anchor and the rover could barely move forward. In addition, it was now more difficult to drive straight ahead.

The time before the onset of winter had become too short to send the rover to the north slope of McCool Hills. Before the energy ran out, the decision was made to drive to the Low Ridge Haven, only a few meters away , which should offer Spirit a sufficient slope towards the sun during the winter. Finally, Spirit reached this point, which made it possible to hibernate over a 12-degree incline to the sun. The distance to this point was 6,876 meters.

During the winter, a multi-stage experiment was carried out: Approx. One millimeter of soil was removed with the stone grinding tool, analyzed with the Mössbauer spectrometer, and photographed with the microscope camera and all 13 color filters of the panorama camera. This was done 3 times in total. In addition, another high-resolution panorama called McMurdo Pan of the area was recorded.

2nd half of 2006 - Low Ridge Haven

Spirits driveway on and next to the Homeplate. Spirit hibernated once near the Low Ridge , once on the northern slope of Winterhaven and at Troy

Spirit was now 1000 Martian days on the Martian surface and was in a 12-degree position towards the sun at Low Ridge Haven , which should bring the rover through the winter. During the winter, the energy production of the solar cells sank to 275 watt hours per sol on August 18. Spirit received new software during the winter stay. This enabled him to process images faster and the robotic arm was given the ability to work even more autonomously. Long-term observations were made of the ground churned up by the stationary wheel to determine any changes.

On July 29th, Spirit survived the coldest night on Mars to date. Model calculations showed that the temperatures near the surface must have fallen to around minus 97 degrees.

Since the right front wheel was still defective in the first driving test after this winter, longer distances were hardly possible. Spirit drove into the Silica Valley, a very small valley east of Home Plate.

1st half of 2007 - Silica Valley

Video of a dust devil in the Gusev crater, enhanced contrast. It has a diameter of about 34 meters.

Spirit recorded image sequences with the navigation camera to detect dust devils moving across the plain. A region is recorded several times and the image is only saved if it changes. In this way, uninteresting surveillance images could be discarded immediately. The rover drove back to a place called Tyrone . Here the rover with its stuck wheel churned up the ground during a long journey, and white and yellow sand came to light. A salty composition was also determined here. It was decided to go back to home plate, which Spirit could not analyze before the onset of winter. Along the way, the intervening Mitcheltree Ridge was examined by scientists to find out whether this formation is an extension of Home Plate or an independent rock layer.

In May, another troubled place called Gertrude Weise was examined carefully. This sand consisted of 90% silicates . In most cases it takes water to create such a concentrated build-up of silicate. A possible origin for the silicate deposit could be the influence of the sand with acidic steam, which was produced by volcanic activity. Another possibility is that water from a hot spring is responsible for the changes. Home Plate and the surrounding area may have been affected by a hydrothermal system millions of years ago. This would have created good conditions for life on Mars .

2nd half of 2007 - global dust storm

Churned, silicate-rich sand at Gertrude Weise

At the beginning of the second half of 2007, a severe global sandstorm, such as that only occurs every 3 Martian years, began to form. This severely affected the continued operation of both rovers. The dew value, which measures the permeability of the atmosphere to sunlight, rose sharply within a week, so that only 8.7% direct sunlight reached the ground and the rover's energy production fell from 750 to 490 watt hours per sol. For a person on Mars, the atmosphere during the storm would be like an overcast sky and hazy air on Earth. In mid-August, the energy levels leveled off at 260–300 watt hours per sol, and Spirit was able to undertake smaller activities again.

One of the targets here was the stone Innocent Bystander (uninvolved bystanders ), so named because it was accidentally broken when it was rolled over by Spirit's wheels. This turned out to be a godsend as it allowed the inner areas of the stone to be analyzed. There was evidence that this object might have formed in a fumarole or hot spring.

In September, after several attempts, Spirit was able to drive onto the surface of home plate to conduct detailed investigations. After the storm subsided, the atmosphere became more permeable again, but the dust that was blown up began to settle on the solar cells. As the third winter was soon approaching and the energy situation soon became more precarious, a wintering place had to be found again. A location was selected in the northwest corner of home plate so that the rover could be parked with a steep incline in the north direction. The rover made poor progress with its stuck wheel and got stuck in a sandy hollow called Tartarus . Spirit was able to free itself from it, but the time at the beginning of winter was becoming increasingly scarce. Therefore, it was decided on Earth to reintroduce Mars time (as at the beginning) in order to use the time as optimally as possible. After three weeks, Spirit was able to reach its wintering quarters.

By December 17, Spirit had traveled 7,527 meters on Mars.

1st half of 2008 - hibernation

The main concern continued to be the energy situation of Spirit. Therefore, an attempt was made to park the rover on the north slope of Home Plate as steeply as possible. An incline of about 30 degrees was needed to get the rover over the winter. At the end of December 2007, 60% of the solar cells were covered by dust, which was the strongest coverage to date. It was assumed that by the winter solstice on June 26, the degree of coverage would increase to up to 70%. Until February, the rover was navigated down the slope in small, sometimes only centimeter-wide trips. An incline to the north of 29.9 degrees could be achieved. This should give the rover a chance to survive the winter. As far as energy was available, another high-resolution panorama of home plate called Bonestell was taken. Sometimes no actions were carried out, only the batteries were charged. Communication with the earth was also minimized and all unneeded instruments were switched off. By the winter solstice, energy production had dropped to 225 watt hours per sol.

2nd half of 2008 - winter sand storm

Spirit had so far covered 7,528 meters in 1715 Martian days (Sols) and was still on the northern slope of Home Plate. In October, Spirit began moving from his position back to home plate. But just now, with the already low energy production, a local dust storm was brewing near the Gusev crater by mid-November and the amount of energy produced sank to just 89 watt hours, the absolute minimum during the mission of both rovers. Despite all energy-saving measures, the rover required at least 141 watt hours to operate, so the rover had to fall back on its internal battery. It was also problematic that the solar conjunction occurred, during which Mars is behind the sun when viewed from the earth and therefore no signals from the Mars probes could reach the earth for two weeks. The rover was all on its own. After this conjunction, Spirit got in touch again, confirming that he had survived this local sandstorm, and later left his winter quarters.

1st half of 2009 - sand trap

Near Troy , where Spirit got stuck in May 2009.

Spirit began to drive around Home Plate from the north, as the direct route over this elevation was not passable. The next target was a volcanic ridge called "von Braun" further south of Home Plate. Spirit had traveled 7,726 meters so far and was in an area called the "West Valley" next to home plate. On Sol 1892, May 1st, the rover came into contact with very loose, soft material in the West Valley. In the process, Spirits wheels dug into the loose ground. During the first attempts at rescue, the rover made only centimeters of progress. It was feared that the underside of the vehicle might touch a stone. For this reason, blurred images of the underside were made with the microscope camera on the robot arm, which at least helped for a rough assessment of the situation. As a result of several wind cleaning events, electricity production rose to 843 watt hours on May 27 and later even to 945 watt hours per day. This gave Spirit enough energy for investigations again while the engineers tried to recreate the situation with a test rover on Earth.

The rover used its instruments to examine the churned up sand, which turned out to be a mixture of basaltic and silicate-rich materials. It was also recognized that the surface of the silicate-rich material forms a crust. This could have been formed by the influence of water, in which the water-soluble iron sulfates are released and the remaining calcium sulfates solidify.

2nd half of 2009 - Free Spirit

Spinning wheels when attempting to drive spirit out of the sand trap (Sol 2117).

In order not to drive the rover further into the sand through incorrect navigation commands, the current position of the rover was analyzed as precisely as possible. In addition, attempts were made to simulate the situation of the rover on earth with an engineering model as precisely as possible in order to determine the optimal travel movements in the Martian sand. At the same time, NASA started a media campaign called Free Spirit (Eng. "Liberate Spirit", but also "Free Spirit") in order to let the public participate in the progress.

It turned out that Spirit had driven over a crater filled with sand and covered with a firmer crust and collapsed in the process; the crater was called Scamander . After several months of tests on earth, the first attempts to drive Spirit out of its sand trap began.

After six months, the first drive commands were sent, which provided for Spirit to be moved in two separate stages, each 2.50 meters north. Due to the expected slip of the wheels and the resulting “spinning”, however, it was assumed that the real gain in terrain would only be in the millimeter range. The first driving test was canceled automatically by the Spirit computer because certain security settings were exceeded. A number of such journeys were made over the next few weeks, but only managed movements in the millimeter range. The new position of the rover was analyzed intensively after each trip. During the rescue attempts, the right rear wheel of the rover failed, so that Spirit only had four operational wheels. The situation of Spirit became more and more critical due to the upcoming Martian winter and the ever decreasing energy supply.

1st half of 2010 - Marswinter at Troy

The Mars rover Spirit has been on Mars for six years, that is 3.2 Martian years. He has been stuck in the sand since May 1, 2009 and was unable to free himself even after the maneuvers that had been carried out since November 2009. The most problematic at the time was the angle of inclination of the rover and thus the alignment of the solar cells. There was a risk that the rover would no longer be able to produce enough energy in the coming Mars winter to warm its electronics. Depending on the available energy, the activities to free the rover were therefore scaled back in the coming weeks. NASA estimated that if conditions remained the same, Spirit might no longer have enough energy in May.

On January 26, 2010, NASA announced that all efforts to free Spirit from the sand had been stopped. The rover should continue to be used as a stationary research platform. You should only try to tilt the rover as far as possible towards the sun in order to ensure the energy supply.

The last movement of the wheels took place on February 8, 2010, but did not bring about the hoped-for change in the inclination of the rover and thus no more favorable alignment of the solar cells. Overall, Spirit had moved 34 centimeters since mid-January and had its solar panels only aligned 9.5 degrees towards the sun. So the situation was rather unfavorable, but the mission leaders were optimistic that Spirit would survive the winter. April 27, 2010 was Sol 2245 for Spirit. On this day it should still have been functional; since it was already in a low power mode at the time, it would have broken the Viking 1's "longevity record". Thus Spirit would have been the longest functioning space probe on Mars at this point in time. 21 days after the actual defect in Spirit, the sister probe Opportunity broke the record.

2nd half of 2010 - attempts at communication

The last radio signals from the rover were received on March 22, 2010 - Spirit has been silent since then. NASA suspected that the rover had gone into a deep sleep phase due to the low battery charge, in which all systems including communications were switched off. Meanwhile, however, the batteries would continue to be charged by the energy generated by the solar cells. However, since the vehicle could not be optimally aligned to the sun before winter, this energy was probably not enough to supply the heating elements with sufficient energy, so that the temperature inside the probe dropped to as low as −55 ° C and the circuit boards were damaged by the cold On-board electronics should have come. As soon as the state of charge was sufficient for operation again, there would be a chance that the rover would automatically wake up and start communicating again. This status is called "Solar Groovy".
Since the winter solstice in the southern hemisphere on May 13, 2010, temperatures and the duration of sunshine have increased again.
In the event of a mission time error due to the internal chronometer being interrupted, the rover would initially only listen to radio signals once every hour for 20 minutes after waking up in order to save energy, but not actively transmit. To counter this problem, so-called "Sweep & Beep" signals have been sent several times an hour since July 28, 2010, which inform the rover that an active remote station is available. The rover should answer this with a beep in the X-band and switch to configuration mode.
Until the end of the year, however, no beacon signals were received despite a direct request to broadcast.

1st half of 2011 - continued silence and end of mission

In addition to the “Sweep & Beep” program that began in mid-2010, the daily time window for communication has been extended to several levels. This happened in the event that the rover clock deviated more than expected from the mission time and the rover was communicating at the same time as the Mars Reconnaissance Orbiter. The longest sunshine duration of the Martian year for the rover was reached around March 10, 2011, thus also the highest energy production by the solar cells. Since then the duration of sunshine has decreased again. To counter a possible failure of the rover's primary X-band communication system, two additional strategies were pursued from mid-March 2011: on the one hand, the rover's separate UHF communication system was called by the Mars orbiters serving as communication relays, and on the other hand, it was activated of the backup output stage of the X-band transmitter requested from the rover. Despite all communication efforts, no signal could be received from Spirit. On May 25, 2011, NASA announced that it would cease its efforts.

Scientific results

See also Scientific Results of the Mars Exploration Rover Mission

In contrast to the spectacular discoveries made by the sister probe Opportunity on the opposite side of the planet on Meridiani Planum , Spirit's primary mission was unable to provide any evidence of a former body of water at the landing site in the Gusev Crater. All rocks examined were basalts, although there was evidence that some of them may have been hydrothermally influenced. Apart from the Aeolian dust and sand drifts, sedimentary rocks have not yet been discovered. There are also no other indications of the geological activity of flowing water, which seems surprising insofar as the exploration of the crater from orbit clearly showed that once at least for a short time, huge masses of water should have shaped the landscape on a larger scale. Possibly this can actually already be explained by the fact that the water only flooded the area in a very short catastrophic event, so that there was no extensive deposition of sediments like on Meridiani Planum . With one exception, the entire area is more reminiscent of the well-known landing sites of the Viking probes and Mars Pathfinder .

It wasn't until the exploration of the Columbia Hills, and especially home plate, that the picture changed. In the Silica Valley, east of Home Plate, the rover had found a white substance in its wheel tracks, which the investigations revealed to be silicon dioxide . Home Plate and the surrounding area may have been affected by a hydrothermal system millions of years ago. This would have created good conditions for life on Mars . The Clovis stone also contains evidence of earlier water; goethite was found by the Mößbauer spectrometer . Otherwise, meteorological observations were made, such as depicting dust devils and sunsets as well as solar and lunar eclipses. Furthermore, Spirit constantly monitored the so-called Tau value, or measured the permeability of the atmosphere.

See also

• Chronology of the missions to Mars
• List of space probes
• List of man-made objects on Mars

Web links

Commons : Spirit (space probe)  - collection of images, videos and audio files

• Mars Exploration Rover - site of JPL NASA (English)
• Mars Exploration Rover - Special page from Raumfahrer.net
• Gallery with all photos of Spirit (english)
• Log of the Mars rover "Spirit"
• Mission details (English, PDF, 1.4 MiB)
• Spirit data to at solarviews (English)
• MER-A Spirit Mars Rover

Individual evidence

1. ↑ Space Shuttle Columbia Crew Memorialized On Mars NASA press release, January 6, 2004
2. ^ NASA Concludes Attempts to Contact Mars Rover Spirit. In: NASA News Release 2011-156. NASA, May 24, 2011, accessed on May 25, 2011 (English): "A transmission that will end on Wednesday, May 25, will be the last in a series of attempts." 
3. ↑ NASA: NASA Extends Operations for Its Long-Lived Mars Rovers October 15, 2007
4. ↑ MER Analysts Notebook on Wustl.edu
5. ^ Mars Rover Surprises Continue; Spirit, Too, Finds Hematite. In: NASA News Release 2004-161. NASA, June 25, 2004, accessed May 25, 2011 . 
6. ^ Mars Rovers Break Driving Records, Examine Salty Soil. In: NASA News Release 2005-038. NASA, March 2, 2005, accessed May 25, 2011 . 
7. ↑ JP Greenwood, RE Blake: Phosphorus Geochemistry of Martian Rocks and Soils: Evidence for Acidic Weatherin at Gusev and Meridiani. (PDF; 179 kB) 2006, accessed on May 25, 2011 (English). 
8. ↑ ^{a b} NASA Rover Finds Clue to Mars' Past And Environment for Life. In: NASA News Release 2010-189. NASA, June 3, 2010, accessed May 25, 2011 . 
9. ^ Meteor Search by Spirit, Sol 668. NASA, accessed on November 28, 2015 (English). 
10. ^ Nancy Atkinson: Spirit Rover Still Providing New Evidence for Past Water on Mars. June 3, 2010, accessed May 25, 2011 . 
11. ^ Spirit's Wind-Driven Traveler on Mars (Spirit Sol 486). NASA, May 27, 2005, accessed May 25, 2011 . 
12. ↑ Geoffrey A. Landis, PG Geissler, R. Greeley, MT Lemmon, J. Maki, LDV Neakrase, SD Thompson, D. Waller, PL Whelley, and the MER Athena Science Team: Dust Devils in Gusev Crater: A second Year of Observations By The Spirit Rover. (PDF; 495 kB) 2007, accessed on May 25, 2011 (English). 
13. ↑ Mars Rover Spirit Unearths Surprise Evidence of Wetter Past. NASA, May 21, 2007, accessed May 25, 2011 . 
14. ↑ Mars Rover Yielding New Clues While Lodged in Martian soil. NASA, June 25, 2009, accessed May 25, 2011 . 
15. ↑ Sandtrapped Mars Rover Makes Big Discovery. NASA, December 2, 2009, accessed May 25, 2011 . 
16. ↑ Pranika Jain: Spirit on Mars… 6-year old, but ain't looking good! (No longer available online.) ABH News January 4, 2010, archived from the original on November 19, 2010 ; accessed on May 25, 2011 (English). 
17. ↑ Stefan Deiters: Spirits darn seventh year. Astronews.com, January 12, 2010, accessed May 25, 2011 . 
18. ^ Now a Stationary Research Platform, NASA's Mars Rover Spirit Starts a New Chapter in Red Planet Scientific Studies. In: NASA News Release 2010-030. NASA, January 26, 2010, accessed January 27, 2010 . 
19. ↑ Mars rover becomes research station. ORF, January 27, 2010, accessed on January 27, 2010 . 
20. ↑ Stefan Deiters: Spirit before a difficult winter. astronews.com, February 12, 2010, accessed May 25, 2011 . 
21. ↑ Nasa gives Mars rover lost spiegel.de
22. ↑ NASA Concludes Attempts To Contact Mars Rover Spirit nasa.gov, accessed May 25, 2011