NASA’s Comet Nucleus Tour (CONTOUR) Mishap Investigation
Board (MIB) identified four possible causes for the failure
of the comet-rendezvous mission launched in July 2002. The
Board concluded the probable proximate cause for this
accident was structural failure of the spacecraft due to
plume heating during the embedded solid-rocket motor burn.

However, the lack of telemetry and observational data,
immediately prior to and during the burn, and the lack of
recoverable debris, leave open the possibility that one of
several other problems could have led to the accident. The
alternate possible causes are catastrophic failure of the
solid rocket motor; collision with space debris or
meteoroids; and loss of dynamic control of the spacecraft.

NASA was not able to re-establish contact with the spacecraft
on August 15, 2002, following a propulsive maneuver involving
the solid rocket motor. On August 22, 2002, the Associate
Administrator for Space Science established the NASA CONTOUR Mishap Investigation Board with Theron Bradley Jr., NASA Chief Engineer, as chair. The purpose of the Board was to
examine the processes, data and actions surrounding the
events of August 15; to search for proximate and root causes;
and develop recommendations that may be applicable to future

Based on various facts and data, the MIB concluded the
alternate possible causes were less likely than the
identified proximate cause. Nonetheless, in the spirit of
constructively improving future mission reliability, the
Board drew conclusions, identified lessons learned, and made
recommendations based on the broader range of possible
causes, according to Bradley.

Launched on July 3, 2002, CONTOUR was intended to encounter
at least two comets and perform a variety of investigations
and analyses of the comet material. It remained in Earth
orbit until August 15, 2002, when an integral Alliant
Techsystems STAR 30BP solid rocket motor was fired to leave
orbit and begin the transit to the comet Encke.

CONTOUR was programmed to re-establish telemetry contact with
the ground following the burn, however, no signal was
received. The mission design did not provide for telemetry
coverage during the solid rocket motor burn and no provision
was made to optically observe the burn.

Active attempts to contact CONTOUR were unsuccessful. On
August 16, 2002, limited ground observations identified what
appeared to be three separate objects on slightly divergent
trajectories near, but behind, CONTOUR’s expected position.
Further attempts to contact CONTOUR were made through
December 20, 2002, when NASA and Johns Hopkins
University/Applied Physics Laboratory (APL), Laurel, Md.,
concluded the spacecraft was lost. The project manager at APL
oversaw the technical implementation of the project and was
responsible for the design, development, test and mission

The MIB established Root Causes and Observations contributing
to the failure, and recommendations for each in the Report.

“NASA will apply the lessons from CONTOUR to future
missions,” Bradley said. He stated the report represented a
lot of tough detective work by the many individuals and
organizations involved in the investigation. “The lack of
data meant the investigators could leave no stone unturned in
their search for possible causes,” he said.

The CONTOUR Mishap Investigation Board Report and information about NASA is available on the Internet at: