Mars Global Surveyor (MGS)
Mars Global Surveyor (MGS) was the first successful U.S. mission launched to Mars since the Viking mission in 1976. After a 20-year absence at the planet, Mars Global Surveyor ushered in a new era of Mars exploration with its five science investigations. Mars Global Surveyor arrived at Mars on September 11, 1997 (September 12, UTC), and has contributed a multitude of findings, including signs of past, persistent water such as an ancient delta and currently active water features in the gullies of canyon walls. After nearly a decade of discovery, MGS went silent 2nd November, 2006.
Mars Global Surveyor was a well-designed space craft that successfully operated since launch on November 7, 1996 until a battery failure in 2nd November, 2006. To enable the spacecraft to last nearly a decade, the Mars Global Surveyor team worked creatively to conserve fuel and invigorate the ageing spacecraft.
The spacecraft, fabricated at the Lockheed Martin Space Systems plant in Denver, Colorado, looks like a rectangular-shaped box with wing-like projections extending from opposite sides. The body (or bus) houses the computers, radio system, solid-state data recorders, fuel tanks, and other equipment. Attached to the outside of the bus are several rocket thrusters, which were fired to adjust the spacecraft's path during cruise to Mars and to modify the spacecraft orbit around the planet.
Fully loaded with propellant at the time of launch the vehicle weighed 1,060-kilograms (2,342 pounds). The spacecraft is about 3 meters (10 feet) tall with its braking engine and instruments. The bus or main body of the spacecraft measures 1.2 by 1.2 meters (4 by 4 feet) and is 12 meters (40 feet) across from tip to tip when the solar panels are fully unfolded. The high-gain antenna is deployed on a 2-meter-long (6-1/2-foot) boom.
To minimize costs, spare units left over from the Mars Observer mission were used in portions of the spacecraft's electronics and for some of the science instruments. The spacecraft design also incorporated new hardware - the radio transmitters, solid-state recorders, propulsion system, and composite material bus structure-and retains many backup and redundant features of the original Mars Observer design in case of failure of critical elements such as the primary processors, recorders or transmitters.
The solar arrays, which always point toward the Sun (when the spacecraft isn't behind the planet), provided 980 watts of electricity for operating the electronic equipment and for charging nickel hydrogen batteries. The batteries provided electricity when the spacecraft is mapping the dark side of Mars. To maintain appropriate operating temperatures, most of the outer exposed parts of the spacecraft, including the science instruments, are wrapped in thermal blankets.
Spacecraft communications with Earth utilized X-band frequencies for radio tracking, return of science and engineering telemetry, commanding, and the radio science experiments. Primary communications to and from the spacecraft occur through the 1.5-meter-diameter (4.9-foot) high-gain antenna. Mars Global Surveyor can receive instructions from Earth at a maximum rate of 12.5 commands per second.
The MGS carried a number of instruments on board:
1) MOC (Mars Orbiter Camera) - This camera produced a daily wide-angle image of Mars similar to weather photographs of the Earth, and also took narrow-angle images. These two pictures are examples of what Mars looks like in late northern summer. Mars Global Surveyor (MGS) orbits around the red planet 12 times a day. Each orbit goes from pole to pole. Over the course of a single day, the wide angle cameras of the Mars Orbiter Camera (MOC) system take 24 pictures--12 red and 12 blue--that are assembled to create a daily global map.
2) MOLA (Mars Orbiter Laser Altimeter) - This experiment measured the height of Martian surface features like mountains and depths of valleys.
3) TES (Thermal Emission Spectrometer) - This instrument studied the atmosphere and mapped the mineral composition of the surface by analysing infrared radiation, which scanned for heat emitted from the surface of Mars.
4) MAGNETOMETER (Electron Reflectometer) - The magnetometer studied the magnetic properties of Mars to gain insight into the interior of the planet and better understand the early history and evolution of Mars
5) RADIO SCIENCE (Gravity Field Experiment)
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|NASA MGS project web page|