The rover has continued to function effectively over seventeen times longer than NASA planners expected, allowing it to perform extensive geological analysis of Martian rocks and planetary surface features; as of 2008 its mission is ongoing. An archive of approximately weekly updates on its status can be found at the NASA/JPLwebsite Initial scientific results from the first phase of the mission (roughly, the 90-sol prime mission) were published in a special issue of the journal Science
The scientific objectives of the Mars Exploration Rover mission are to:
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.
Assess whether those environments were conducive to life.
During the next two decades, NASA will conduct several missions to address whether life ever arose on Mars. The search begins 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 do not have the ability to detect life directly, they are offering very important information on the habitability of the environment in the planet's history.
Science instruments carried
Panoramic Camera (Pancam): for determining the mineralogy, texture, and structure of the local terrain.Miniature Thermal Emission Spectrometer (Mini-TES): for identifying promising rocks and soils for closer examination and for determining the processes that formed Martian rocks. The instrument also scans skyward to provide temperature profiles of the Martian atmosphere.Mössbauer Spectrometer (MB): for close-up investigations of the mineralogy of iron-bearing rocks and soils.Alpha Particle X-Ray Spectrometer (APXS): for analysis of elements that make up rocks and soils.Magnets: for collecting magnetic dust particles. The Mössbauer Spectrometer and the Alpha Particle X-ray Spectrometer will analyze the particles collected and help determine the ratio of magnetic particles to non-magnetic particles. Microscopic Imager (MI): for obtaining close-up, high-resolution images of rocks and soils.Rock Abrasion Tool (RAT): for removing dusty and weathered rock surfaces and exposing fresh material for examination by instruments onboard.
Landing site: Columbia Memorial Station
Spirit was targeted to a site that appear to have been affected by liquid water in the past, the Gusev crater, a possible former lake in a giant impact crater about 10 km from the center of the target ellipse at latitude 14.5718° S, longitude 175.4785° E.
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.
Events and discoveries
The primary surface mission for Spirit was planned to last 90 Sols. The mission received several extensions and as of April 2008 had passed 1500 Sols, more than 17 times the primary mission length. On August 11, 2007, Spirit became the Mars lander with the second longest operational duration on the surface of Mars 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. Currently the Mars lander with longest operational period is Viking 1 which lasted for 2245 Sols on the surface of Mars.
An archive of approximately weekly updates on the rover's status can be found at Spirit Update Archive. The following paragraphs discuss the more notable findings.
"Sleepy Hollow," a shallow depression in the Mars ground near NASA's Spirit rover, was targeted as an early destination when the rover drove off its lander platform. NASA scientists were very interested in this crater. It is 9 meters (30 feet) across and about 12 meters (40 feet) north of the lander.
"Just as the ancient mariners used sextants for 'shooting the Sun,' as they called it, we were successfully able to shoot the Sun with our panorama camera, then use that information to point the antenna," said JPL's Matt Wallace, mission manager.
First color photograph
To the right is the first color image 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)
January 21 flash memory management anomaly
On 2004January 21 (Sol 18), Spirit abruptly ceased communicating with mission control. The next day the rover radioed a 7.8 bit/s beep, confirming that it had received a transmission from Earth but indicating that the 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