Donald L. Savage
Headquarters, Washington, D.C.             January  5, 1994  (Phone:
202/358-1547)

James Gately
Naval Research Laboratory, Washington, D.C.  (Phone:  202/767-2541)

RELEASE: 94-1

MARS OBSERVER INVESTIGATION REPORT RELEASED

     The final report by the independent investigation board  on the failure of
the Mars Observer spacecraft was delivered  today to NASA Administrator Daniel
S. Goldin by Dr. Timothy  Coffey, Chairman of the board.  Dr. Coffey is
Director of  Research at the Naval Research Laboratory, Washington, D.C.

     The Mars Observer spacecraft was to be the first U.S.  spacecraft to study
Mars since the Viking missions 18 years  ago.  The Mars Observer spacecraft
fell silent just 3 days  prior to entering orbit around Mars, following the
pressurization of the rocket thruster fuel tanks.

     Because the telemetry transmitted from the Observer had  been commanded
off and subsequent efforts to locate or  communicate with the spacecraft
failed, the board was unable  to find conclusive evidence pointing to a
particular event  that caused the loss of the Observer.

     However, after conducting extensive analyses, the board  reported 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.

     Additionally, this high spin rate precluded proper  orientation of the
solar arrays, resulting in discharge of  the batteries.  However, the spin
effect may be academic,  because the released MMH would likely attack and
damage  critical electrical circuits within the spacecraft.

     The board's study concluded that the propulsion system  failure most
probably was caused by the inadvertent mixing  and the reaction of nitrogen
tetroxide (NTO) and MMH within  titanium pressurization tubing, during the
helium  pressurization of the fuel tanks.  This reaction caused the  tubing to
rupture, resulting in helium and MMH being released  from the tubing, thus
forcing the spacecraft into a  catastrophic spin and also damaging critical
electrical  circuits.

     Based on tests performed at the Jet Propulsion  Laboratory (JPL)
Pasadena, Calif., the board concludes that  an energetically significant amount
of NTO had gradually  leaked through check valves and accumulated in the tubing
during the spacecraft's 11-month flight to Mars.

     In addition, the report listed other possible causes of  the loss of the
spacecraft as:

     *  failure of the electrical power system, due to a  regulated power bus
short circuit;

     *  NTO tank over-pressurization and rupture due to  pressurization
regulator failure;

     *  the accidental high-speed ejection of a NASA standard  initiator from a
pyro valve into the MMH tank or other  spacecraft system.

     Other concerns noted by the board included:

     *  a need to establish a policy to provide adequate  telemetry data of all
mission-critical events;

     *  the lack of post-assembly procedures for verifying  the cleanliness and
proper functioning of the propellant  pressurization system;

     *  a current lack of understanding of the differences  between the
characteristics of European Space Agency and NASA  pyro-initiators;

     *  the potential for power bus short circuits, due to  single component or
insulation failure;

     *  the potential for command and data handling control  systems to be
disabled by single-part failure;

     *  the lack of fault protection external to the  redundant crystal
oscillator (RXO) should one of its two  outputs fail;

     *  the absence of information, in the telemetry, on the  actual state of
the RXO's backup oscillator;

     *  deficiencies in systems engineering/flight rules;

     *  too much reliance placed on the heritage of  spacecraft hardware,
software and procedures for near-Earth  missions, which were fundamentally
different from the  interplanetary Mars Observer mission; and

     *  the use of a firm fixed-price contract restricted the  cost-effective
and timely development of the unique and  highly specialized Mars Observer
Spacecraft.

     Dr. Coffey notes, "We were challenged to conduct an  extraordinarily
complex investigation in which we had no hard  evidence to examine nor
communications with the spacecraft.  However, after an extensive analysis
covering every facet of  the mission, operations and hardware, I believe that
we are  justified in arriving at the conclusions we have.  If our  findings
will help to ensure that future missions won't  suffer a similar fate, we feel
we will have achieved our  purpose."

     Dr. Coffey also expressed his appreciation for the  support provided to
the investigation board by the six  technical teams, other NRL and Air Force
Phillips Laboratory  contributors, NASA representatives, the JPL Project Team
and  Investigation Board, and the Martin Marietta Astro Space  technical teams.

     "I commend Dr. Coffey and his team for the thoughtful  and thorough
research into the tragic loss of the Mars  Observer," said Dr. Wesley Huntress,
Jr., Associate  Administrator for NASA's Office of Space Science, Washington,
D.C.  "Their work will help and guide us in formulating a  corrective action
plan to help ensure future success as we  plan for recovering our Mars science
exploration objectives."

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