Spirit (rover)
Spirit (English for spirit, soul ) is a started in June 2003 U.S. space probe NASA exploration of the planet Mars. It was originally called Mars Exploration Rover A, short- MER -A, and was renamed after the start in Spirit. Spirit landed on January 4, 2004 at Gusev Crater. The sister probe Opportunity ( MER -B) landed on January 25, 2004 at the Meridiani Planum. The landing site is named in honor of the perished in the Columbia tragedy astronauts " Columbia Memorial Station". Since 22 March 2010, no more contact was added to the probe. Since all attempts at contact had failed to Spirit during the following year, NASA has on 25 May 2011 ended the active contact with the rover, which corresponds to a de facto end to the mission.
Mission
Spirit looked for traces of any former water present and explored the landing site geology. From the results, the scientists worldwide involved hoped new insights into the history of the Martian climate. The Gusev crater was selected as a scientific goal in a complicated process, as can be seen on photographs of the orbiting Mars spacecraft Mars Global Surveyor and 2001 Mars Odyssey distinct traces of a former lake.
From a technical point of view, landing in Gusev Crater was one of the most challenging, since in this region can be very strong winds occur. However, according to a modification of the landing unit involved in the project, NASA engineers gave the green light for the mission. The landing unit specific reference to three pictures that were taken shortly before landing and high-contrast features such as craters auswertete, the horizontal velocity of the landing module. The determined horizontal movement direction and speed could be reduced later by a designated engine system. Thus it was possible, the scientific standing paramount goal of Gusev Crater, finally selected as the landing site.
The mission duration should initially be guaranteed 90 days, but Spirit had far exceeded this. The mission has been extended regularly. Since April 2009, the rover was stuck in the sand. By January 2010, was tried in vain to free him by driving maneuvers. On March 22, 2010, the last signals from Spirit were collected. It was assumed that the rover was in a kind of deep sleep, as there was Martian winter at his position. In the hope that the rover called again with rising sun, one more month communication campaign was launched by NASA. Since all communication attempts were unsuccessful, the rover was abandoned on 25 May 2011 by NASA.
Overall Spirit worked in 2210 Mars days ( sol ) on the surface and put it 7730 m on the Martian surface back. A total of 156002 images were transmitted to the cameras ( panoramic and navigation cameras), of which 6315 shots with the microscope camera. Is 367 measurements were performed with the X-ray spectrometer and AXPS 932 measurements with the Mössbauer spectrometer.
Technique of probe
The two rovers Spirit and Opportunity are identical. Therefore, there is a detailed description of the technique, Mars Exploration Rover.
Unlike Mars Pathfinder Spirit is called no fixed ground station, but a wheeled robot, " Rover ". It is 1.6 m long, 1.5 m high and 185 kg. According to the specification, he should be able, depending on the surface condition on the day of about 100 m, a total of about 3 km before and stay up to six months operational on the planet's surface. This exceeds the capabilities of the predecessor of the Sojourner Mars Pathfinder mission in 1997 by about a factor of 60 The rover is NASA itself as " robotic geologist " ( robotic geologist ) and has designated six independently driven wheels on stilts shaped telescopic legs. He carries in addition to various panoramic ( Pancam ), navigation ( navcam ) and threat detection cameras ( hazcams - hazard recognition cameras ) a pivoting arm with a rock microscope (also with camera ), several spectrometers ( Mössbauer, alpha particles, infrared) and a mechanical tool that is able to brush off rock surfaces and deep to drill on a few square centimeters to several millimeters in order to examine the interior accessible rocks can ( rat - rock abrasion tool ). The wheels are moved individually and not used solely for locomotion, but can also be used as mining equipment to dig up the ground and thus to examine a few centimeters of the soil profile mechanically and photographically. The rover has about solar panels and rechargeable batteries is to save energy before sunset brought into a state of rest and again " awakened" after sunrise by a radio signal. With the help of his antennas, the device images and measurement results can either send the used as intermediate stations for earth orbiting Orbiter NASA and the ESA or directly to earth and receive commands from there. Because of the relatively high running time of the signals from the earth (depending on planets distance up to 20 minutes ), the rover must with its on-board computers to some extent can act autonomously.
Course of the mission
1st half of 2004 - Primary Mission
After a journey of seven months and a distance traveled of 487 million kilometers, the probe entered the atmosphere of Mars on January 4, 2004. It was protected by a heat shield, first decelerated in the atmosphere down to the speed of sound. Then a parachute on its lines a missile system was installed above the probe, which should compensate for horizontal movements in the atmosphere unfolded. Shortly before touchdown protectively around the probe set airbags were inflated abruptly. The last few meters above the surface were then covered in free fall. After the lander was then come to rest, the airbags were deflated again. Spirit landed at 5:35 clock CET south of the Martian equator in Gusev crater. 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 reddish-brown sand and stones.
During the first days the NASA ground team the remains of airbags tried the Spirit during the final landing phase protected to vacate by pulling out of the way. This blocked the front ramp, which should use the rover to exit the lander. In addition, cable compounds were dissolved in the intermediate wheels and anchors that secured the robot arm from Spirit with small detonators. A total of 126 of such detonators were fired since landing of Spirit. Only then Spirit could raise up and develop its front and rear wheels. The lander has a total of three ramps. Since the airbags still block the front ramp, the rover turned around 120 degrees clockwise to exit via a directed north-west dodge the landing ramp unit.
After leaving the lander, the rover placed three meters back route and explored within two days, the chemical and mineralogical relationships with the devices installed on the robot arm. For the first time could be made with a microscope on another planet, here are the first pictures. The weather on Mars continued to play with good. The temperatures fluctuated during the Martian summer between minus 10 and minus 75 degrees Celsius and the atmosphere was marred by no sandstorms.
The first to be examined stone lay two meters away and received by the NASA scientists the name Adirondack. Spirit required for these races 30 minutes and the journey time alone was just two minutes. The stone " Adirondack " should be under the microscope and then with two coming from Germany instruments, the Mössbauer spectrometer of the Mainz physicist Göstar Klingelhöfer and the APXS ( Alpha Particle X - Ray Spectrometer) at the Max Planck Institute for Chemistry, Mainz, examined.
On January 21 ( Sol 18) the NASA ground team lost in Pasadena sudden contact with Spirit. The scientific and technical data could not be received in the specified time window. NASA initially charged a storm on Australia responsible 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 could be determined that Spirits computer constantly re- launched, a total of 130 times. Reason for the reboot was that too many files were stored in the file system of the computer, and then storage areas have been overwritten, which were essential for the functioning of the Rovers. After the rover was instructed to delete the data and start the control computer again, ( Sol 33) was able to perform normal operations resumed on February 6.
On the first working day following the scientific failure, the surface of the Adirondack baptized stone was brushed over an area of 4.5 centimeters with a brush of Spirit. For the first time in the history of unmanned space thus a hole was drilled into a rock on another planet. From the analysis of the 2.4 mm deep hole with a diameter of 45 millimeters, the researchers expecting to find clues to the geology of the stone.
It turned out that the surrounding rocks were basaltic nature and showed no influence of water. Therefore, it was chosen as the first long-term goal of the baptized by NASA as Bonneville crater. There, it was hoped that access to deeper layers of rock. To the 90th Sol Spirit had reached this crater, but this seemed to be completely uninteresting compared to the geological environment. It was decided, therefore, the Rover despite its low life of 90 days and planned to send 600 m distance to about 2 km from the Columbia Hills, which were the last hope of still to come across traces of water.
Second half of 2004 - Columbia Hills
Spirit drove from the crater Bonneville in a direct line toward the Columbia Hills. The infrastructure has been defined precisely by the engineers only in difficult terrain. Usually, however, the rover drove in autonomous mode. He reached the hill at 158 Sol to two miles distance. At the base of the Columbia Hills some promising rocks were discovered, including an unusually weathered stone called pot -of- gold. To analyze this stone fell heavily Spirit, as it was in a rough and slippery terrain in contrast to the previously investigated rocks. After a close examination with the AXPS - ray spectrometer and Mössbauer spectrometer turned out that this stone contains hematite. This rock can form, among others, in connection with water.
Since the energy produced by the solar panels dropped by the sinking sun and dust deposits on and on, you led (as in Opportunity ) the so-called Deep Sleep Mode a. Here, the Rover is completely switched off during the night to save energy, even at the risk that this instrument could be damaged.
On sol 184 after a few driving tests began the ascent to the Columbia Hills. The route was chosen so that the solar panels of Spirit are always possible aligned towards the sun. Meanwhile, you measure the right front an increased current resistance. To relieve this wheel all further runs were carried out backwards. Sol at 205 another unusual stone called Clovis was examined. In the spectrum recorded from the Mössbauer instrument was found a clear signature of the iron- bearing mineral goethite. Goethite contains water in the form of hydroxyl as part of its structure. This is considered one of the safest evidence for water on the red planet since goethite is formed only in connection with water.
Spirit also led several successful communication tests with the probe Mars Express ESA. The vast communication occurs via the probes Mars Odyssey and Mars Global Surveyor NASA.
First half of 2005 - Climbing the Hills Husband
Spirit was now an Earth year on Mars and drove slowly up the hill mentioned Husband Hill. This was difficult because of the way through many obstacles rocky and sandy sections went. This led often to the fact that the wheels of the rover went mad and the rover's journey could not be driven. In February, the computer Spirit received an update of the software to operate more autonomous can.
In addition, the amount of energy recovered decreased in spite of the increased inclination to the sun, due to a nurse, in contrast to probe Opportunity relatively thick layer of dust on the solar panels is always further. In the meantime, watching Spirit this time of year an increased number of dust devils, which suggests that at this time of year is very windy in Gusev Crater. To 9 March 2005 met one of these dust devils the rover and freed the solar cells from the accumulated dust. The energy level rose by 800 watt-hours per day. This was Spirit almost twice as much energy available as this cleaning event.
The higher the rover climbed, the more it seemed to be scientifically interesting. On Sol 407 of Larry 's Lookout called ridge was reached below the summit and made panoramic photographs of the area. Near Paso Robles rocks and the churning of the wheels of Spirit sand were analyzed at the location. With the AXPS - ray spectrometer bright, sulfur-containing material has been identified. In addition, the highest measured concentration of salt a rock or soil was measured on Mars here. With the determined information of the other instruments, it was assumed that the main component is an iron sulfate salt having incorporated therein water molecules.
2nd half of 2005 - summit of Husband Hill
By August, Spirit was still only 100 meters from the summit. It emerged that the Husband Hill has two peaks, one of which is slightly higher than the other. On September 29, the 618th Martian day, Spirit reached the real summit of Husband Hill. The rover was thus the first spacecraft that had conquered a mountain on another celestial body. The total distance traveled totaled 4973 meters. The summit itself was rather flat. Spirit took from the summit on a 360 degree panorama in real colors, which included the entire Gusev crater. Night watching the Rover, the two Martian moons Phobos and Deimos, in order to determine their circulation parameters even more closely. In addition, an attempt was made to photograph meteors, since the Mars moved at this time through the meteor stream of comet Halley.
On Sol 656 Spirit led observations of the martian sky and the atmospheric transmittance using the panoramic camera through to make coordinated research with the Hubble Space Telescope in orbit.
From the summit, Spirit was already in a valley a striking formation that Home Plate realize. However, Spirit had to later go on to McCool Hill in order to align its solar panels toward the sun in the winter can. So he began in late October with the descent from Husband Hill, and made his way into this valley, where he was to visit the home plate and later that hill.
On the way to Spirit reached down as a named Comanche rock formation on sol 690 result it was found that this rock is composed of about 16 to 34 percent of magnesium -iron carbonate. This mineral forms in wet and neutral pH environments, but dissolves in acid liquids. Here they had found an important indication that on Mars non-acidic water must also have existed.
First half of 2006 - ride to McCool Hill
The descent of Husband Hill went ahead quickly. On the way to home plate Spirit came on a pass called El Dorado dune field.
Spirit had reached home plate, and found that it is a cooled volcanic formation that showed a noticeable layer structure on February 10. However, now broke in the winter time and it was decided to discontinue the investigation of home plate and trying to achieve with the Rover the north side of McCool Hills to bring him into a favorable tilt toward the sun during the upcoming Martian winter. Just now blocked the right front of the rover, which behaved erratically for some time. Spirit had ergomonic the broken wheel by the other five wheels from now, but had this bike like an anchor and the rover was hardly move. Moreover, it had become more difficult to go straight.
The time to onset of winter had become too short to send the rover to the northern slope of McCool Hills. Before the energy was running out, they decided to drive to which only a few meters away Low Ridge Haven, the Spirit should provide a sufficient inclination towards the sun during the winter. Finally reached Spirit the body which allowed the wintering over a 12 -degree tilt toward the sun. The route up to this point was 6876 meters.
During the winter time, a multi-stage experiment was conducted: The stone grinding tool about a millimeter soil was removed, analyzed with the Mössbauer spectrometer, photographed with the microscope camera and all 13 color filters of the panoramic camera. This was performed 3 times. In addition, again a high-resolution panorama called McMurdo Pan was added to the environment.
2nd half of 2006 - Low Ridge Haven
Spirit was now 1000 Mars 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 solar cells dropped from up to 275 watt-hours per sol on August 18. Spirit received new software during the winter stay. He was able to process images faster and the robot arm him with the ability to be more autonomous. There were long-term observations of the turbulent stationary- wheel ground carried out to determine possible changes.
On July 29, Spirit survived the coldest night so far on Mars. Model calculations have shown that the temperature near the surface to about minus 97 degrees must be like.
Since the first driving test after this winter the front right wheel was still defective, larger distances were hardly possible. Spirit drove to the Silica Valley, a very small valley east next to home plate.
1st half of 2007 - Silica Valley
Spirit took on image sequences with the navigation camera to discover dust devils that run across the plain. Here a region is photographed many times and only when the image changes, it will also be stored. So uninteresting surveillance images were equal discarded. The rover then drove to a place called Tyrone again. Here rummaged the rover with its fixed wheel at a more recent trip to ground, and there was white and yellow sand to light. Here also a salt-containing composition was determined. It was decided once again to go to the Home Plate, the Spirit before the onset of winter could not be analyzed in more detail. Along the way, the intervening ridge Mitcheltree Ridge has been studied by scientists to find out if this formation is an extension of home plate, or an independent rock layer.
In May, another troubled spot named Gertrude, it has been put under the microscope. This sand was 90 % of silicates. In most cases, water is necessary to produce such a concentrated accumulation of silicate. A possible origin for the silica deposits could be the influence of sand with acid vapor, which was produced by volcanic activity, be. Another possibility would be that hot spring water is responsible for the changes. The Home Plate and the surrounded area could have been influenced by a hydrothermal system millions of years ago. This would have created good conditions for life.
H2 2007 - Global Dust Storm
At the start of the second half of 2007 there was a serious, global dust storm, as it only occurs every 3 Mars years to form, began. This affected the continued operation of both Rover massive. The dew - value, which measures the transmittance of the atmosphere for sunlight, rose sharply within a week, arrived so that only 8.7% of direct sunlight on the ground and the energy production of the rover from 750 to 490 watt-hours per sol sank. For a person on Mars, the atmosphere would be like during the storm as with an overcast sky and hazy air on Earth. In mid-August, the energy values leveled off at 260-300 watt-hours per sol, and Spirit could do smaller activities again.
One goal of the stone was Innocent Bystander ( German bystander ), so called because it was broken unintentionally by Spirits wheels when rolling over. This turned out to be a stroke of luck, since thereby the inner regions of the stone could be analyzed. In this object there were indications that it may have formed in a fumarole or a hot spring.
In September Spirit was able to ride on the surface of Home Plate after several attempts, thus allowing for detailed investigations. After the storm subsided again, the atmosphere was indeed re- permeable, however, the dust raised began to sell the solar cells. As soon as the third winter was in a suit and the energy situation was precarious soon, had to be found again a wintering area. This is where a place was chosen in the northwest corner of home plate, so that the rover could be parked with a strong inclination to the north. Unfortunately, the Rover came through his fixed wheel very little headway, and even ran yet in a sandy valley called Tartarus. Spirit was able to free it up though, but the time to onset of winter was becoming increasingly scarce. Therefore it was decided on the ground, again ( as in the beginning ) to introduce the Mars time to make the best use of time. After three weeks, Spirit could then reach its wintering quarters.
Until December 17, Spirit had covered 7527 meters on Mars.
1st half of 2008 - Hibernation
The main concern was still the energy situation of Spirit. Therefore, an attempt was made to park the rover on the northern slope of Home Plate as much inclined as possible. It has a slope of about 30 degrees is required, so that the rover came over the winter. End of December 2007, the solar cells covered 60% of dust, the strongest coverage. It was assumed that until the winter solstice on June 26, the coverage would rise to 70 %. By February, the rover has been shut navigated the slope in small, sometimes only centimeter -wide journeys. Here, a slope to the north of 29.9 degrees was achieved. Thus, the rover should have a chance to survive the winter. As far as energy was available to, another high-resolution panoramic home plate called Bonestell was taken. Sometimes there is no actions were carried out, but only charged the batteries. Also, the communication with the ground is minimized and off all the instruments are not required. Until the winter solstice, the energy production dropped to 225 watt-hours per sol.
Second half of 2008 - Winter sandstorm
Spirit had covered in 1715 Martian days ( sols ) so far 7528 meters and was still on the northern slope of Home Plate. In October it was begun Spirit to move from its position back to the home plate. But just now with the already low energy production was brewing until mid-November, a local dust storm near the Gusev crater together and the produced amount of energy dropped to only 89 watt hours, the absolute power minimum during the mission of both rovers. To operate the rover needed despite all the energy-saving measures at least 141 watt-hours, so that the rover had to rely on its internal battery. The problem was that now entered the solar conjunction, during which the Mars seen from Earth is behind the sun and thus for two weeks, no signals of Mars probes were able to reach the earth. The rover was all on his own. After this conjunction is Spirit reported but again, confirmed the fact that he had survived this local sandstorm, and later left his winter quarters.
1st half of 2009 - Sand trap
Spirit began, the home plate to drive around from the north, because the direct path of this survey was not passable. The next goal was a volcanic hill called " von Braun " south of Home Plate. Spirit had traveled far 7726 meters and was located in an area called " West Valley " next to home plate. On Sol 1892, 29 April, the rover came here in the West Valley with very loose, soft material in contact. Here, Spirits wheels dug in loose soil. In the first liberation Try the rover moved forward inch by inch only. It was feared that the underside of the vehicle combination could put on a stone. Therefore, blurring the bottom were taken with the microscope camera on the robot arm that helped at least a rough estimate of the situation. Through several wind cleaning events, the power output rose on May 27, to 843 watt-hours, and later even to 945 watt hours per day. This Spirit was back enough energy for investigations available, while the engineers tried with a test rover on Earth to recreate the situation.
The rover studied with his instruments the troubled sand which proved to be a mixture of basaltic and silicate-rich materials. In addition, it was recognized that the surface of the silicate-rich material forms a crust. This could have been formed by the influence of water by the water-soluble iron sulfates are released and the remaining calcium sulfates solidify.
2nd half of 2009 - Free Spirit
In order not to further drive the rover due to incorrect navigation commands in the sand, the current position of the rover was analyzed as accurately as possible. In addition, an attempt was made to recreate the situation of the rover on Earth with an engineering model as accurately as possible in order to determine the optimal travel movements in the Martian sand. NASA launched in parallel, a media campaign called Free Spirit (Eng. "Free Spirit", but also "Free Spirit " ) to share to the public on the progress.
It turned out that Spirit had driven over a sand filled and covered with a firmer crust crater and was then broken by this crust. The crater was named Scamander. After several months of testing on the ground, the first attempts, Spirit started out again down from its sand trap.
After six months, the first operation commands were sent, which provided it, Spirit to move in two separate stages over each 2.5 meters in a northerly direction. Due to the expected slippage of the wheels and the resulting " spin " you walked, however, believe that the real terrain profit would only be in the millimeter range. The first driving test was canceled by the computer from Spirit itself, because certain security settings have been exceeded. During the next few weeks a number of such trips were conducted, but only movements in the millimeter range brought about. After each ride, the new position of the rover has been extensively analyzed. While trying to escape then fell out of the right rear of the rover, Spirit so that only had four operational wheels enabled. The situation became increasingly critical of Spirit, the imminent Martian winter and the ever- declining energy supplies.
1st half of 2010 - Mars winter at Troy
The Mars rover Spirit now for six years was located on Mars, which are 3.2 Mars years. He stuck since 23 April 2009 as the sand and could not free by the since November 2009 carried out maneuvers. Most problematic were at the time, the inclination angle of the rover and thus the orientation of the solar cells. There was a danger that the next Mars Rover winter could no longer produce enough energy to warm his electronics. Depending on the available energy activities for the liberation of the Rovers were therefore scaled back in the coming weeks. NASA estimated that Spirit could no longer have enough energy during sustained situation in May.
On 26 January 2010, NASA announced that all efforts were set to free Spirit from the sand. The rover should continue to be used as a stationary research platform. It should only be still trying to tilt the rover as far as possible towards the sun, to ensure the energy supply.
The last movement of the wheels was held on 8 February 2010, but did not bring the hoped-for change in the tilt of the rover and thus more favorable orientation of the solar cells. Overall, Spirit moved since mid-January to 34 inches and had its solar panels currently aligned only 9.5 degrees toward the sun. The situation was therefore quite unfavorable, yet the mission managers were optimistic that Spirit survived the winter. The 27th April 2010, for the Spirit Sol 2245th On that day, he should still be functional, as it was at the time already in a low power mode, it would be the "longevity record " of Viking 1 break. Thus Spirit would be the longest- working Mars spacecraft.
Second half of 2010 - communication attempts
The last radio signals of the Rovers were received on March 22, 2010 - since then was silent Spirit. NASA suspected that the rover has gone into a deep sleep because of the low battery state, in which all systems are turned off, including the communication. Meanwhile, the batteries were, however, continues to be charged by the energy generated by the solar cells. However, since the vehicle before the winter could not be optimally aligned to the sun, this energy handing probably not for a sufficient supply of the heating elements, so that the temperature dropped inside the probe up to -55 ° C, and the frost- damage to boards board electronics may have come. When the state of charge is sufficient for operation again, there was a chance that the rover again automatically wakes up and starts to communicate. This status is called "Solar Groovy ". Since the winter solstice in the southern hemisphere on May 13, 2010 temperatures and sunshine duration increased again. For the case of a mission -time error by exposing the internal chronometer the rover would first hear after waking up only once per hour for 20 minutes on radio signals in order to save energy but not actively transmitting. To address this problem, several times an hour so-called "Sweep & Beep " signals have been sent since July 28, 2010, who told the rover that an active partner is present. This should be the Rover answer with a beep signal at X-band and switch to configuration mode. By the end of the year but no beacons were received despite direct invitation to shipment.
1st half of 2011 - Next silence and end of mission
In addition to the already begun in mid-2010 "Sweep & Beep" program, the daily time window for communication on several levels has been extended. This was done for the case where the rover clock more than expected from the mission time is different, and communicates the rover at the same time as the Mars Reconnaissance Orbiter. The highest for the Rover sunshine duration of the Mars year was reached about 10 March 2011, therefore the highest energy production by the solar cells. Since then, the sunshine duration decreases. In order to address a failure of the primary X-band communication system of the rover, 2011, two additional strategies were from mid-March followed: Firstly, the separate UHF communication system of the rover was launched by serving as a communications relay Mars orbiter, and on the other hand has an activation the back- end stage of the X-band transmitter from the rover requested. Despite all communication efforts, no signal could be received from Spirit. On 24 May 2011, NASA announced to suspend their efforts.
Scientific Results
See also Scientific Results of the Mars Exploration Rover Mission
In contrast to the spectacular discoveries of the sister probe Opportunity on the opposite side of the planet at Meridiani Planum Spirit could not provide evidence for a former water at the landing site in Gusev in its primary mission. All of the investigated rocks were basalts, when there was also evidence that some of them may hydrothermally were affected. Aside from aeolian dust and sand drifts, sedimentary rocks have not yet been discovered. Other clues to the geological activity flowing water missing, what seems surprising, as the exploration of the crater was clearly visible from orbit that this was once at least in the short term huge water masses should have marked the landscape on a larger scale. Perhaps this can be explained by the fact already that the water has flooded the area just in a very short catastrophic event, so it did not come for the areal deposition of sediments as on Meridiani Planum. The whole environment reminds except one rather of the known landing sites of the Viking orbiters and Mars Pathfinder.
Only with the investigation of the Columbia Hills and in particular the Home Plate the picture changed. In Silica Valley, east of Home Plate, the rover had found in his wheel tracks a white substance, which becomes apparent in the investigations as silica. The Home Plate and the surrounded area could have been influenced by a hydrothermal system millions of years ago. This would have created good conditions for life. The stone Clovis also contains references to earlier water, was found by the Mössbauer spectrometer goethite. Otherwise, meteorological observations have yet been taken, such as the mapping of dust devils and sunsets as well as solar and lunar eclipses. Further monitored constantly Spirit called Tau value, or measuring the transmittance of the atmosphere.