- 09.25.92: Launch (17:05:01 UT)
- 08.22.93: Contact Lost (01:00 UT)
- 08.27.93: End of Mission
- Status: Mission Lost at Mars
- imaging system
- thermal emission spectrometer
- pressure modulator infrared radiometer
- laser altimeter
- magnetometer/electron reflectometer
- gamma-ray spectrometer
- radio science experiment
- Mars balloon relay receiver
The bus and electronics of the Observer series of spacecraft, used to study the terrestrial planets and near-Earth asteroids, were derived from the Satcom-K and DMSP/TIROS spacecraft. The rectangular bus section was 2.1 x 1.5 x 1.1 m. During the cruise phase of the mission, the high-gain antenna and the booms for the magnetometer (MAG/ER) and gamma-ray spectrometer (GRS) were partially deployed. When fully deployed, the two booms were each 6 m long. The 1.5 m diameter high-gain antenna was, when fully deployed, on a 5.5 m boom to allow for clearance over the solar array when the antenna was pointed toward Earth.
Contact with Mars Observer was lost on August 21, 1993, three days before scheduled orbit insertion, for unknown reasons and has not been re-established. Despite vigorous efforts to regain contact, Mars Observer remained quiet. When the spacecraft did not reestablish command as a result of a stored program that was designed to do so in case of five days of silence, mission planners finally gave up hope on salvaging the mission. It is not known whether the spacecraft was able to follow its automatic programming and go into Mars orbit or if it flew by Mars and is now in a heliocentric orbit. Later investigation concluded the most probable cause of the mishap was a fuel line rupture during fuel tank pressurization which would have caused the spacecraft to spin uncontrollably. Although none of the primary objectives of the mission were achieved, cruise mode data were collected up to loss of contact.
The results of a five-month investigation proved to be inconclusive, but one likely cause of the catastrophic failure may have been a fuel line rupture that could have damaged the spacecraft's electronics, throwing the vehicle into a spin. The total cost of the Mars Observer mission including development, construction, launch, and ground support is estimated at $813 million.
