Close Shave? NASA Dismisses Sn Whisker Worries Print E-mail
Written by Mike Buetow   
Friday, 09 June 2006 07:25
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.)
Last Updated ( Monday, 12 June 2006 07:03 )
 

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