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Oops! JPL Plays Rough, Breaks Probe
By Paul Hoversten
Washington Bureau Chief
posted: 02:41 pm ET
23 March 2000
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By Paul Hoversten WASHINGTON -- NASA engineers running ground tests on a $40 million science satellite mistakenly shook it with 10 times as much force as planned, cracking its wing-like solar arrays and damaging the spacecraft's frame, NASA officials told SPACE.com Thursday. The March 21 incident at NASA's Jet Propulsion Laboratory (JPL) caused "significant damage" to the High Energy Solar Spectroscopic Imager (HESSI) and will delay its launch for at least six months, said Mark Hess, a spokesman at Goddard Space Flight Center in Greenbelt, Maryland, which controls the spacecraft. "The spacecraft structure has been damaged and the solar arrays were cracked. They will have to be replaced. It's not clear about the main instrument on the spacecraft, nor the structure itself," Hess said. "There's some optimism that at least the spacecraft continued to work normally until it was shut off," he said. The 853-pound (388-kilogram) spacecraft was designed to study solar flares for three years from an orbit 360 miles (600 kilometers) above Earth. HESSI was scheduled to launch from a Pegasus rocket from Cape Canaveral, Florida in July. Launch now will occur no earlier than next January. 
"We're not talking about a total loss... But there's no good time for anything like this to happen. It wouldn't be good news anytime you have an accident like this."
A NASA review board will be appointed immediately to investigate the blunder -- the latest for the beleaguered JPL, already under fire for its role in last year's failures of two Mars probes. "Apparently they were testing the spacecraft doing vibration testing, which is the normal kind of thing you do to simulate launch stresses," Hess said. "They shook it about 10 times higher than what they should have so it got 10 times what was the appropriate level for the test." The spacecraft was to have received a force equal to 2 Gs, or two times the pressure of normal Earth gravity. Instead, HESSI got a dose of 20 Gs. "We don't know how it happened. They've convened a failure review board and impounded the spacecraft and the facility itself so they can review all the data. We expect that process to take four to six weeks," Hess said. The HESSI spacecraft, which was built by Spectrum Astro of Arizona, had been at JPL for about two weeks for preflight testing. The same sort of tests could have been done at Goddard, which controls the mission, but managers decided to use JPL because of its proximity to Arizona, where the spacecraft was built. 
The skeleton of the HESSI spacecraft. HESSI was scheduled to leave the Pasadena, California center in mid-May for Florida, where it was to be prepared for launch. The spacecraft was on a "vibration table" in a sterile "clean room" at JPL when the accident occurred, said Nancy Lovato, a JPL spokeswoman. "This test was the 11th of the day. There had been 10 others, and all the previous tests had gone fine. Typically, the testing would have continued for another couple of days," she said. HESSI sailed through the thermal testing -- in which it was subjected to alternately warm and cold temperatures -- just fine. But something went terribly wrong in the vibration test, which lasted about a minute. Looking on were engineers from JPL, Goddard and the Kennedy Space Center, along with technicians from spacecraft-builder Spectrum Astro and project scientists from the University of California-Berkeley. Someone shut down the spacecraft's systems once it became apparent it had been shaken far more than intended. "It could be any number of things" that caused the vibration test to go wrong, Lovato said. "We're not talking about a total loss [of spacecraft]," she said. "We'll be able to recover quite a bit. But there's no good time for anything like this to happen. It wouldn't be good news anytime you have an accident like this."
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