Artistic view of a Mars Exploration Rover on Mars
|Launch date||June 10, 2003|
|Launch vehicle||Delta II 7925 9.5 rocket|
|Mission duration||Planned: 90 Martian solar days (~92 Earth days)
Operational: 2269 days from landing to last contact (2208 sols)
Mobile: 1944 Earth days landing to final embedding (1892 sols)
Total: 2695 days from landing to mission end (2623 sols)
|Homepage||JPL's Mars Exploration Rover|
|Mass||185 kg (408 lb) (Rover only)|
|Power||Solar panels (Photovoltaic)|
|Batteries||Rechargeable lithium ion|
Spirit, MER-A (Mars Exploration Rover – A), is a robotic rover on Mars, active from 2004 to 2010. It was one of two rovers of NASA's ongoing Mars Exploration Rover Mission. It landed successfully on Mars at 04:35 Ground UTC on January 4, 2004, three weeks before its twin, Opportunity (MER-B), landed on the other side of the planet. Its name was chosen through a NASA-sponsored student essay competition. The rover became stuck in late 2009, and its last communication with Earth was sent on March 22, 2010.
The rover completed its planned 90-sol mission. Aided by cleaning events that resulted in higher power from its solar panels, Spirit went on to function effectively over twenty times longer than NASA planners expected. Spirit also logged 7.73 km (4.8 mi) of driving instead of the planned 600 m (0.4 mi), allowing more extensive geological analysis of Martian rocks and planetary surface features. Initial scientific results from the first phase of the mission (the 90-sol prime mission) were published in a special issue of the journal Science.
On May 1, 2009 (5 years, 3 months, 27 Earth days after landing; 21.6 times the planned mission duration), Spirit became stuck in soft soil. This was not the first of the mission's "embedding events" and for the following eight months NASA carefully analyzed the situation, running Earth-based theoretical and practical simulations, and finally programming the rover to make extrication drives in an attempt to free itself. These efforts continued until January 26, 2010 when NASA officials announced that the rover was likely irrecoverably obstructed by its location in soft soil, though it continued to perform scientific research from its current location.
The rover continued in a stationary science platform role until communication with Spirit stopped on sol 2210 (March 22, 2010). JPL continued to attempt to regain contact until May 24, 2011, when NASA announced that efforts to communicate with the unresponsive rover had ended. A formal farewell was planned at NASA headquarters after the Memorial Day holiday and was televised on NASA TV.
The scientific objectives of the Mars Exploration Rover mission were to:
- Search for and characterize a variety of rocks and soils that hold clues to past water activity. In particular, samples sought will include those that have minerals deposited by water-related processes such as precipitation, evaporation, sedimentary cementation or hydrothermal activity.
- Determine the distribution and composition of minerals, rocks, and soils surrounding the landing sites.
- Determine what geologic processes have shaped the local terrain and influenced the chemistry. Such processes could include water or wind erosion, sedimentation, hydrothermal mechanisms, volcanism, and cratering.
- Perform calibration and validation of surface observations made by Mars Reconnaissance Orbiter instruments. This will help determine the accuracy and effectiveness of various instruments that survey Martian geology from orbit.
- Search for iron-containing minerals, identify and quantify relative amounts of specific mineral types that contain water or were formed in water, such as iron-bearing carbonates.
- Characterize the mineralogy and textures of rocks and soils and determine the processes that created them.
- Search for geological clues to the environmental conditions that existed when liquid water was present.
- Assess whether those environments were conducive to life.
During the next two decades, NASA would continue to conduct missions to address whether life ever arose on Mars. The search began with determining whether the Martian environment was ever suitable for life. Life, as we understand it, requires water, so the history of water on Mars is critical to finding out if the Martian environment was ever conducive to life. Although the Mars Exploration Rovers did not have the ability to detect life directly, they offered very important information on the habitability of the environment during the planet's history.
Design and construction
Spirit (and its twin, Opportunity) are six-wheeled, solar-powered robots standing 1.5 m (4.9 ft) high, 2.3 m (7.5 ft) wide and 1.6 m (5.2 ft) long and weighing 180 kg (400 lb). Six wheels on a rocker-bogie system enable mobility over rough terrain. Each wheel has its own motor. The vehicle is steered at front and rear and is designed to operate safely at tilts of up to 30 degrees. Maximum speed is 50 mm/s (2 in/s); 0.18 km/h, although average speed is about 10 mm/s (0.4 in/s). Both Spirit and Opportunity have pieces of the fallen World Trade Center's metal on them which were "turned into shields to protect cables on the drilling mechanisms".
Solar arrays generate about 140 watts for up to four hours per Martian day (sol) while rechargeable lithium ion batteries store energy for use at night. Spirit's onboard computer uses a 20 MHz RAD6000 CPU with 128 MB of DRAM, 3 MB of EEPROM, and 256 MB of flash memory. The rover's operating temperature ranges from −40 °C to +40 °C (−40 °F to 104 °F) and radioisotope heater units provide a base level of heating, assisted by electrical heaters when necessary. A gold film and a layer of silica aerogel provide insulation.
Communications depends on an omnidirectional low-gain antenna communicating at a low data rate and a steerable high-gain antenna, both in direct contact with Earth. A low gain antenna is also used to relay data to spacecraft orbiting Mars.
Fixed science instruments include
- Panoramic Camera (Pancam) – examines the texture, color, mineralogy, and structure of the local terrain.
- Navigation Camera (Navcam) – monochrome with a higher field of view but lower resolution, for navigation and driving.
- Miniature Thermal Emission Spectrometer (Mini-TES) – identifies promising rocks and soils for closer examination, and determines the processes that formed them.
- Hazcams, two B&W cameras with 120 degree field of view, that provide additional data about the rover's surroundings.
The rover arm holds the following instruments
- Mössbauer spectrometer (MB) MIMOS II – used for close-up investigations of the mineralogy of iron-bearing rocks and soils.
- Alpha particle X-ray spectrometer (APXS) – close-up analysis of the abundances of elements that make up rocks and soils.
- Magnets – for collecting magnetic dust particles.
- Microscopic Imager (MI) – obtains close-up, high-resolution images of rocks and soils.
- Rock Abrasion Tool (RAT) – exposes fresh material for examination by instruments on board.
The cameras produce 1024-pixel by 1024-pixel images, the data is compressed, stored, and transmitted later.
The primary surface mission for Spirit was planned to last at least 90 sols. The mission received several extensions and lasted about 2,208 sols. On August 11, 2007, Spirit obtained the second longest operational duration on the surface of Mars for a lander or rover at 1282 Sols, one Sol longer than the Viking 2 lander. Viking 2 was powered by a nuclear cell whereas Spirit is powered by solar arrays. Until Opportunity overtook it on May 19, 2010, the Mars probe with longest operational period was Viking 1 which lasted for 2245 Sols on the surface of Mars. On March 22, 2010, Spirit sent its last communication, thus falling just over a month short of surpassing Viking 1's operational record. An archive of weekly updates on the rover's status can be found at the Spirit Update Archive.
Spirit's total odometry as of March 22, 2010 (sol 2210) is 7,730.50 meters (4.80 mi).
The Spirit Mars rover and lander arrived successfully on the surface of Mars on 04:35 Ground UTC on January 4, 2004. This was the start of its 90-sol mission, but solar cell cleaning events would mean it was the start of a much longer mission, lasting at least until 2010.
Landing site: Columbia Memorial Station
Spirit was targeted to a site that appears to have been affected by liquid water in the past, the crater Gusev, a possible former lake in a giant impact crater about 10 km (6.2 mi) from the center of the target ellipse at .
After the airbag-protected landing craft settled onto the surface, the rover rolled out to take panoramic images. These give scientists the information they need to select promising geological targets and drive to those locations to perform on-site scientific investigations.
The panoramic image below 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.
"Sleepy Hollow," a shallow depression in the Mars ground at the right side of the above picture, 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.
"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 Steven Amato, mission manager.
First color image
To the right is the first color image derived from images taken by the panoramic camera on the Mars Exploration Rover Spirit. It was the highest resolution image 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 University. The picture shown originally had a full size of 4,000 by 3,000 pixels. However, a complete pancam panorama is even 8 times larger than that, and could be taken in stereo (i.e., two complete pictures, making the resolution twice as large again.) The colors are fairly accurate. (For a technical explanation, see colors outside the range of the human eye.)
The MER pancams are black-and-white instruments. Thirteen rotating filter wheels produce multiple images of the same scene at different wavelengths. Once received on earth, these images can be combined to produce color images.
Sol 17 (January 21, 2004) flash memory management anomaly
On January 21, 2004 (Sol 17), 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 craft believed it was in a fault mode. Commands would only be responded to intermittently. This was described as a very serious anomaly, but potentially recoverable if it were a software or memory corruption issue rather than a serious hardware failure. Spirit was commanded to transmit engineering data, and on January 23 sent several short low-bitrate messages before finally transmitting 73 megabits via X band to Mars Odyssey. The readings from the engineering data suggested that the rover was not staying in sleep mode. As such, it was wasting its battery power and overheating – risk factors that could potentially destroy the rover if not fixed soon. On Sol 20, the command team sent it the command SHUTDWN_DMT_TIL ("Shutdown Dammit Until
Above: An approximate true-color view of Adirondack, taken by Spirit's pancam.
Right:Digital camera image (from Spirit's Pancam) of Adirondack after a RAT grind (Spirit's rock grinding tool)
|Type of feature||Rock|
Observations of rocks on the plains show they contain the minerals pyroxene, olivine, plagioclase, and magnetite. These rocks can be classified in different ways. The amounts and types of minerals make the rocks primitive basalts—also called picritic basalts. The rocks are similar to ancient terrestrial rocks called basaltic komatiites. Rocks of the plains also resemble the basaltic shergottites, meteorites which came from Mars. One classification system compares the amount of alkali elements to the amount of silica on a graph; in this system, Gusev plains rocks lay near the junction of basalt, picrobasalt, and tephite. The Irvine-Barager classification calls them basalts. Plains rocks have been very slightly altered, probably by thin films of water because they are softer and contain veins of light colored material that may be bromine compounds, as well as coatings or rinds. It is thought that small amounts of water may have gotten into cracks inducing mineralization processes). Coatings on the rocks may have occurred when rocks were buried and interacted with thin films of water and dust. One sign that they were altered was that it was easier to grind these rocks compared to the same types of rocks found on Earth.
Cross-sectional drawing of a typical rock from the plains of Gusev crater. Most rocks contain a coating of dust and one or more harder coatings. Veins of water-deposited minerals are visible, along with crystals of olivine. Veins may contain bromine salts.
Scientists found a variety of rock types in the Columbia Hills, and they placed them into six different categories. The six are: Clovis, Wishbone, Peace, Watchtower, Backstay, and Independence. They are named after a prominent rock in each group. Their chemical compositions, as measured by APXS, are significantly different from each other. Most importantly, all of the rocks in Columbia Hills show various degrees of alteration due to aqueous fluids. They are enriched in the elements phosphorus, sulfur, chlorine, and bromine—all of which can be carried around in water solutions. The Columbia Hills’ rocks contain basaltic glass, along with varying amounts of olivine and sulfates. The olivine abundance varies inversely with the amount of sulfates. This is exactly what is expected because water destroys olivine but helps to produce sulfates.
The Clovis group is especially interesting because the Mössbauer spectrometer(MB) detected goethite in it. Goethite forms only in the presence of water, so its discovery is the first direct evidence of past water in the Columbia Hills's rocks. In addition, the MB spectra of rocks and outcrops displayed a strong decline in olivine presence, although the rocks probably once contained much olivine. Olivine is a marker for the lack of water because it easily decomposes in the presence of water. Sulfate was found, and it needs water to form. Wishstone contained a great deal of plagioclase, some olivine, and anhydrate (a sulfate). Peace rocks showed sulfur and strong evidence for bound water, so hydrated sulfates are suspected. Watchtower class rocks lack olivine consequently they may have been altered by water. The Independence class showed some signs of clay (perhaps montmorillonite a member of the smectite group). Clays require fairly long term exposure to water to form. One type of soil, called Paso Robles, from the Columbia Hills, may be an evaporate deposit because it contains large amounts of sulfur, phosphorus, calcium, and iron. Also, MB found that much of the iron in Paso Robles soil was of the oxidized, Fe+++ form, which would happen if water had been present.
Towards the middle of the six-year mission (a mission that was supposed to last only 90 days), large amounts of pure silica were found in the soil. The silica could have come from the interaction of soil with acid vapors produced by volcanic activity in the presence of water or from water in a hot spring environment.
After Spirit stopped working scientists studied old data from the Miniature Thermal Emission Spectrometer, or Mini-TES and confirmed the presence of large amounts of carbonate-rich rocks, which means that regions of the planet may have once harbored water. The carbonates were discovered in an outcrop of rocks called "Comanche."
In summary, Spirit found evidence of slight weathering on the plains of Gusev, but no evidence that a lake was there. However, in the Columbia Hills there was clear evidence for a moderate amount of aqueous weathering. The evidence included sulfates and the minerals goethite and carbonates which only form in the presence of water. It is believed that Gusev crater may have held a lake long ago, but it has since been covered by igneous materials. All the dust contains a magnetic component which was identified as magnetite with some titanium. Furthermore the thin coating of dust that covers everything on Mars is the same in all parts of 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 first photo of Earth from the surface of another planet in early March 2004.
In late 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)[neologism?] eclipse as Spirit watched Phobos disappear into Mars' shadow. Some of Spirit's star gazing was designed to look for a predicted meteor shower caused by Halley's Comet, and although at least four imaged streaks were suspect meteors, they could not be unambiguously differentiated from those caused by cosmic rays.
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.[clarification needed]
Equipment wear and failures
Both rovers have passed their original mission time of 90 sols many times over and the extended time on the surface, and therefore additional stress on components, has resulted in some issues developing.
On sol 778 (March 13, 2006), the right front wheel ceased working after having covered 4.2 mi (7 km) on Mars. Engineers began driving the rover backwards, dragging the dead wheel. Although this resulted in changes to driving techniques, the dragging effect became a useful tool, partially clearing away soil on the surface as the rover traveled, thus allowing areas to be imaged that would normally be inaccessible. However, in mid-December 2009, to the surprise of the engineers, the right front wheel showed slight movement in a wheel-test on Sol 2113 and clearly rotated with normal resistance on three of four wheel-tests on Sol 2117, but stalled on the fourth. On sols 2100–2101 (Nov 29, 2009), the right rear wheel also stalled and remained inoperable for the remainder of the mission.
Scientific instruments also experienced degradation as a result of exposure to the harsh Martian environment and use over a far longer period than had been anticipated by the mission planners. Over time, the diamond in the resin grinding surface of the Rock Abrasion Tool wore down, after which the device could only be used to brush targets. All of the other science instruments and engineering cameras continued to function until contact was lost; however, towards the end of Spirit's life, the MIMOS II Mössbauer spectrometer took much longer to produce results than it did earlier in the mission because of the decay of its Cobalt 57 gamma ray source which has a half life of 271 days.
- To rover
To commemorate Spirit's great contribution to the exploration of Mars, the asteroid 37452 Spirit 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.
- From rover
On 22 January 27, 2004 NASA memorialized the crew of Apollo 1 by naming three hills to the north of "Columbia Memorial Station" as the Apollo 1 Hills. On 28 February 2, 2004 the astronauts on Space Shuttle 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 as "Anderson", "Brown", "Chawla", "Clark", "Husband", "McCool", and "Ramon"; NASA has submitted these geographical feature names to the IAU for approval.
- Aeolis quadrangle
- Autonomous robot
- Composition of Mars
- Curiosity rover
- Exploration of Mars
- Life on Mars
- List of missions to Mars
- List of rocks on Mars
- Mars Exploration Rover
- Mars Science Laboratory
- Mars Pathfinder
- Opportunity rover
- Scientific information from the Mars Exploration Rover mission
- Space exploration
- Unmanned space mission
- U.S. Space Exploration History on U.S. Stamps
- Viking program
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- Horizons System
- JPL.NASA.GOV: Mars Exploration Rovers
- Mars Exploration Rover Mission: Features
|Wikimedia Commons has media related to: Mars Exploration Rover|
- JPL's Mars Exploration Rover Mission home page
- (obsolete JPL Mars Exploration Rover home page)
- Spirit Mission Profile by NASA's Solar System Exploration
- Planetary Photojournal, NASA JPL's Planetary Photojournal for Spirit
- NASA TV Special Events Schedule for MER News Briefings at JPL
- Mission Status updates from NASA JPL
- Wikisource:NASA MER press briefings
- Finding Spirit: high resolution images of landing site (Mars Global Surveyor – Mars Orbiter Camera)
- JPL's site devoted to the efforts to free Spirit
- MER Analyst's Notebook, Interactive access to mission data and documentation
- SpaceFlightNow Spaceflightnow.com, Status Page last updated May 2004
- Marsbase.net, a site that tracks time on Mars.
- MAESTRO – public version of rover simulation software (requires download, last update October 25, 2004)
- Cornell's rover site: Athena last update 2006
- Finding Spirit: interactive Mars atlas based on Viking images: you can zoom in/out and pan images, to find your preferred site. "Spirit" approximate position is 14.82°S (= −14.82°N), 184.85°W (= 5.15°E) (not working as of June 4, 2008)
- Google map with Spirit landing site marked
- (AXCH) 2004 Mars Exploration Rovers Highlights – News, status, technical info, history, and more.
- New Scientist on Spirit Dust Devils, March 15, 2005
- New Scientist on Spirit Wheel Status, April 3, 2006
- Unmanned Spaceflight.com discussion on Spirit as of 2008-06-04 last updated 2008-06-04
- Full-page, High-res spherical panorama of Spirit in the Columbia Hills, nasatech.net, Nov 23 to Dec 5, 2005 (long download, uses Java)
- Full-page, High-res spherical panorama of Spirit at the summit of Husband Hill, nasatech.net, Nov 23 to Dec 5, 2005 (long download, uses Java)
- Daily Mail article on Spirit, many photos
Image map of Mars
The following imagemap of the planet Mars has embedded links to geographical features in addition to the noted Rover and Lander locations. Click on the features and you will be taken to the corresponding article pages. North is at the top; Elevations: red (higher), yellow (zero), blue (lower).