The Loss of Mars Observer

The Coffey Board report stated that the most probable cause of the loss of communications with the spacecraft on Aug. 21, 1993, was a rupture of the fuel (monomethyl hydrazine (MMH)) pressurization side of the spacecraft's propulsion system, resulting in a pressurized leak of both helium gas and liquid MMH under the spacecraft's thermal blanket. The gas and liquid would most likely have leaked out from under the blanket in an unsymmetrical manner, resulting in a net spin rate. This high spin rate would cause the spacecraft to enter into the "contingency mode," which interrupted the stored command sequence and thus, did not turn the transmitter on.

The board also identified three other possible causes:

The JPL board report added two additional failure scenarios:

Additional information relevant to the loss of Mars Observer includes:

Return to MSSS Home Page

Copyright © 1995 by Malin Space Science Systems, Inc.