Planetary News: Genesis (2004)
Investigation Uncovers Likely Cause of Genesis Mishap; Stardust Team Confident
of Safe Return
By Amir Alexander
15 October 2004
NASA's Mishap Investigation Board looking into the crash of
the Genesis sample return capsule announced yesterday that it has identified
a probable cause of the September 8 mishap. According to the Board, the problem
centers on gravity switch devices, which are designed to be triggered by the
extreme G-forces operating on the capsule during its reentry into Earth’s
atmosphere. Once activated, the switches were to send a signal to the capsule’s
computer, which was in turn to deploy a drogue parachute and then a large
parafoil.
The Board’s investigation has revealed that a design error placed the
gravity switches in an incorrect orientation that partially shielded them
from the capsule’s sharp deceleration in the atmosphere. As a result,
the switches did not engage and failed to signal the computer to deploy the
drogue and parafoil. Without them, Genesis’s sample return capsule sped
towards the ground and slammed into the Earth at over 300 kilometers per hour
(200 mph). Specially trained helicopter stunt pilots, who were waiting in
their aircraft to snatch the capsule from the air as it dangled gently below
the massive parafoil, were left with the job of locating the wreck.
“This single cause has not yet been fully confirmed, nor has it been
determined whether it is the only problem within the Genesis system,” said
Dr. Michael G. Ryschkewitsch, chair of the Mishap Investigation Board. The
Board is working to confirm this proximate cause, to determine why this error
happened, why it was not caught by the test program and an extensive set of
in-process and after-the-fact reviews of the Genesis system.
Despite the setback, the Genesis mission may well turn out a success. Mission
scientists are very optimistic that they will be able to recover nearly all
of the Solar wind samples collected by the spacecraft during its 850 days
in space. It now appears likely that all of the mission’s major goals
will ultimately be met.
The crash of the Genesis capsule raised concern about another sample return
mission, which is now underway. Stardust, designed to collect samples from
a comet and return them to Earth, underwent a dramatic and highly successful
encounter with comet Wild-2 in early January, 2004. It then stowed the dust
grains it had gathered in a sample return capsule, and headed back to Earth.
In January 2006, much like Genesis before it, the Stardust capsule should
settle gently down onto the Utah desert hanging from a large parafoil.
Genesis and Stardust are sister missions that use much of the same hardware
and design elements. It therefore initially seemed that the Genesis mishap
might point to a serious problem with Stardust as well. The recent revelations
by the Mishap Investigation Board of the causes of the Genesis crash, however,
appear to put these concerns to rest.
“We’re all set for a soft landing in Utah at 3am on the night
of January 15, 2006” said Stardust Project Manager Tom Duxbury of NASA’s
Jet Propulsion Laboratory in Pasadena. According to Duxbury, already on September
14 the Mishap Investigation Board notified the Stardust team of its preliminary
conclusions. Even at the time, less than a week after Genesis’s crash
landing, the Board had already determined that the misaligned gravity switches
had likely caused the accident. Duxbury and his team immediately set about
checking the fine details of Stardust’s design and conducting necessary
tests.
The results were reassuring: “The gravity switches were installed incorrectly
on Genesis, but installed correctly on Stardust” Duxbury said confidently.
There is therefore every reason to expect that Genesis’s problems will
not be repeated with Stardust. “Stardust is sleeping very well at night,” he
added.
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