Mars Observer

Mars Observer was a NASA space probe to Mars, which was launched in 1992. In 1993, the contact four days before the entry into Mars orbit lost and could never be restored. The exact cause is unknown.


Mars Observer was launched on 25 September 1992 aboard a Titan III launch vehicle type / Commercial from Launch Complex 40 at Cape Canaveral to Mars. Even during the flight occurred malfunctions, the probe lost several times the orientation due to dirty and defective navigation sensors. On 26 July 1993, the MOC camera made ​​the two single images from Mars that were ever sent from Mars to Earth Observer. When they finally on August 21, 1993, three days before the arrival, began preparations for pivoting in the Mars orbit, Mars Observer no longer reported. All attempts to contact were unsuccessful, so that the probe was officially declared on 22 September 1993 as lost.


  • MOC (Mars Observer Camera): A high-resolution CCD line camera.
  • MOLA (Mars Orbiter Laser Altimeter ): should create a MOLA topographic map of Mars from the time differences of the laser.
  • TES ( Thermal Emission Spectrometer): TES should investigate the mineralogical composition of Mars.
  • RS (Radio Science): RS had sparked with the on-board transmitters through the Martian atmosphere to the earth, so as to examine the structure of the atmosphere.
  • PMIR (Pressure Modulated Infrared Radiometer): should PMIR measure the light emitted from the Martian surface radiation and thus allow conclusions on the climate.
  • GRS (Gamma Ray Spectrometer ): GRS had sought by gamma radiation by water.

Possible Causes

The inquiry commission published the following possible reasons for the failure:

  • Due to an explosion in the engines, the orbiter turned from the normal position. This creates a security mode is enabled, the all running processes - and thus the planned contacting Earth - stopped.
  • The power supply failed after a transistor failed. The transistor series used made ​​it even on board weather satellites.
  • By the failure of the pressure regulator in the fuel tank, the tank is damaged and the probe was not be able to correct its position.
  • The fuel lines were damaged by the pyrotechnic ignition engine.

However, all these causes are speculative, as there was no telemetry at the time of the loss of contact.


The loss of the Mars Observer expensive was a shock for the American space - with him not only one of the most expensive and most ambitious NASA projects, but also the first NASA planetary probe Mariner 8 was lost since 1971. Six of the seven instruments flew on the probes Mars Global Surveyor and 2001 Mars Odyssey back to the red planet. The seventh instrument PMIR should go with the Mars Climate Orbiter to Mars, but did not play due to the loss of the mission. As a consequence also followed for the NASA Discovery program in which instead of a few expensive probes many small, cheap should be started.