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Mars Global Surveyor (MGS) was an American robotic space probe developed by NASA's Jet Propulsion Laboratory and launched November 1996.
MGS was a global mapping mission that examined the entire planet, from the ionosphere down through the atmosphere to the surface.
As part of the larger Mars Exploration Program, Mars Global Surveyor performed atmospheric monitoring for sister orbiters during aerobraking, and helped Mars rovers and lander missions by identifying potential landing sites and relaying surface telemetry.
It completed its primary mission in January 2001 and was in its third extended mission phase when, on 2 November 2006, the spacecraft failed to respond to messages and commands. A faint signal was detected three days later which indicated that it had gone into safe mode.
Attempts to recontact the spacecraft and resolve the problem failed, and NASA officially ended the mission in January 2007.
MGS remains in a stable near-polar circular orbit at about 450 km altitude and as of 1996, was expected to crash onto the surface of the planet in 2050.
Mars Global Surveyor achieved the following science objectives during its primary mission:
-Characterize the surface features and geological processes on Mars.
-Determine the composition, distribution and physical properties of surface minerals, rocks and ice.
-Determine the global topography, planet shape, and gravitational field.
-Establish the nature of the magnetic field and map the crustal remnant field.
-Monitor global weather and the thermal structure of the atmosphere.
-Study interactions between Mars' surface and the atmosphere by monitoring surface features, polar caps that expand and recede, the polar energy balance, and dust and clouds as they migrate over a seasonal cycle.
More information: Mars Exploration
Mars Global Surveyor also achieved the following goals of its extended mission:
-Continued weather monitoring to form a continuous set of observations with NASA's Mars Reconnaissance Orbiter, which reached Mars in March 2006.
-Imaging of possible landing sites for the 2007 Phoenix spacecraft, and the 2011 Curiosity rover.
-Observation and analysis of key sites of scientific interest, such as sedimentary-rock outcrop sites.
-Continued monitoring of changes on the surface due to wind and ice.
On 2 November 2006, NASA lost contact with the spacecraft after commanding it to adjust its solar panels. Several days passed before a faint signal was received indicating that the spacecraft had entered safe mode and was awaiting further instructions.
On 21 and 22 November 2006, MGS failed to relay communications to the Opportunity rover on the surface of Mars. In response to this complication, Mars Exploration Program manager Fuk Li stated, Realistically, we have run through the most likely possibilities for re-establishing communication, and we are facing the likelihood that the amazing flow of scientific observations from Mars Global Surveyor is over.
On 13 April 2007, NASA announced the loss of the spacecraft was caused by a flaw in a parameter update to the spacecraft's system software. The spacecraft was designed to hold two identical copies of the system software for redundancy and error checking. Subsequent updates to the software encountered a human error when two independent operators updated separate copies with differing parameters. This was followed by a corrective update that unknowingly included a memory fault which resulted in the loss of the spacecraft.
Originally, the spacecraft was intended to observe Mars for 1 Martian year (approximately 2 Earth years). However, based on the vast amount of valuable science data returned, NASA extended the mission three times. MGS remains in a stable near-polar circular orbit at about 450 km altitude, and was expected to crash onto the surface of the planet at some point after about 2047 at the time of its original launch, having by then spent fifty years orbiting the red planet. This is to prevent contamination of the Martian surface with any germs that may be stuck to the spacecraft.
More information: Jet Propulsion Laboratory-NASA
The spacecraft circled Mars once every 117.65 minutes at an average altitude of 378 km. The nearly polar orbit (inclination = 93°) which is almost perfectly circular, moved from the south pole to the north pole in just under an hour. The altitude was chosen to make the orbit Sun-synchronous, so that all images that were taken by the spacecraft of the same surface features on different dates were taken under identical lighting conditions. After each orbit, the spacecraft viewed the planet 28.62° to the west because Mars had rotated underneath it. In effect, it was always 14:00 for MGS as it moved from one time zone to the next exactly as fast as the Sun. After seven sols and 88 orbits, the spacecraft would approximately retrace its previous path, with an offset of 59 km to the east. This ensured eventual full coverage of the entire surface.
In its extended mission, MGS did much more than study the planet directly beneath it. It commonly performed rolls and pitches to acquire images off its nadir track. The roll maneuvers, called ROTOs (Roll Only Targeting Opportunities), rolled the spacecraft left or right from its ground track to shoot images as much as 30° from nadir. It was possible for a pitch maneuver to be added to compensate for the relative motion between the spacecraft and the planet. This was called a CPROTO (Compensation Pitch Roll Targeting Opportunity), and allowed for some very high resolution imaging by the onboard MOC (Mars Orbiting Camera).
In addition to this, MGS could shoot pictures of other orbiting bodies, such as other spacecraft and the moons of Mars.
In 1998 it imaged what was later called the Phobos monolith, found in MOC Image 55103.
More information: National Geographic
If Mars formed life,
then life on Earth could have been seeded by life on Mars,
making every life form on Earth descended from Martians.
Neil deGrasse Tyson
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