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  - - The original note follows - -

Date: Thu, 06 Jan 1994 20:55:10 -0500 (EST)
From: "amak@uoft02.utoledo.edu" <AMAK@uoft02.utoledo.edu>
Subject: Mars Observer Final Report
To: fac3194@uoft01.BITNET, edu0021@uoft01.BITNET, lhunter@discovery.oar.net,
 pxc18@psuvm.psu.edu, pkline@nike.heidelberg.edu,
 lib_aca_jo@nwoca.oecn.ohio.gov, wieberd@stolaf.edu


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."