 |
 |
||
 |
|
||
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
||||||||
 |
Planetary News: Genesis (2004)Investigation Uncovers Likely Cause of Genesis Mishap; Stardust Team Confident of Safe ReturnBy Amir Alexander15 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. |
|||||
 |
 |
|||||
[ what is this? ]