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Close Shave? NASA Dismisses Sn Whisker Worries |
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Written by Mike Buetow
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Friday, 09 June 2006 |
WASHINGTON, DC -- NASA has decided to push forward with next month's scheduled launch of its Discovery space shuttle, even in light of an internal report that noted the presence of tin whiskers in some computer avionics boxes.
NASA's decision is a rebuttal to a recent report by The Aerospace Corporation, which found that "The flight rationale currently proposed that would
allow flight 'as is' of critical Flight Control System (FCS) avionics
boxes suspected of whisker infestation cannot be validated with the
available data and, therefore, is not acceptable for flight.
"Catastrophic impacts for tin whisker
generated failures puts not only the Orbiter at risk, but also
potentially the International Space Station and the crew for both
vehicles."
The Aerospace Corp. is a nonprofit corporation that serves the Air Force in the scientific and technical planning and
management of its missile space programs.
Whiskers found on circuit boards in the control boxes were caused by slivers that fell from tin-coated guide rails
onto the boards. In a rebuttal to the
concerns, NASA said its engineers have examined the parts and cleared
them, although new different material would be used for the guide rails
in the future.
In its report, NASA said the concerns over tin whiskers boiled down to a specific set of controllers known as e RJDs (Reaction Jet Drivers). NASA pointed to 30,000 hours of flight
experience during which no discussions of tin whiskers had ever come to light. That, the agency claimed, "strongly suggested that no such
events have occurred."
NASA is aware of tin whisker-related problems: It's Goddard Space Flight Center maintains a Web site that lists historical failures due to tin whiskers.
The scheduled flight would be only the the second mission
since February 2003, when the Columbia burned upon rentry to the
Earth's atmosphere, killing all the astronauts aboard. The flight
window is July 1 to July 19.
(More background on this story and images of whiskers identified in the Aerospace Corp. report are available here.)
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