Launch Date: September 25, 1992
Mission Project Home Page - http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1992-063A
Seventeen years after the successful Viking 1 and Viking 2 missions, Mars Observer was launched on 25 September 1992 to make a detailed study of the red planet. The spacecraft, based on an Earth-orbiting communications satellite, carried a payload of science instruments designed to study the geology, geophysics and climate of Mars.
The primary science objectives for the mission were to: (1) determine the global elemental and mineralogical character of the surface material; (2) define globally the topography and gravitational field; (3) establish the nature of the Martian magnetic field; (4) determine the temporal and spatial distribution, abundance, sources, and sinks of volatiles and dust over a seasonal cycle; and, (5) explore the structure and circulation of the atmosphere.
Contact with Mars Observer was lost on 21 August 1993, three days before scheduled orbit insertion. The spacecraft was about to begin pressurizing its fuel tanks in preparation for the orbit-insertion maneuver when its transmitters went silent and the spacecraft was never heard from again. However, science instruments originally developed for Mars Observer have been flown to Mars on several other orbiters including the Mars Global Surveyor which carried both the TES (Thermal Emission Spectrometer) and the MOLA (Mars Observer Laser Altimeter) instruments as well as the MAG/ER magnetometer, Mars Odyssey which carries a version of the Gamma Ray Spectrometer, and the Mars Reconnaissance Orbiter which carries a version of the Pressure Modulator Infrared Radiometer, now called the Mars Climate Sounder (MCS).