DOH!
www.nature.com
Published online: 18 October 2004; | doi:10.1038/news041018-1
Flawed drawings caused spacecraft crash
Nicola Jones
Upside-down switches stopped parachutes from opening.
The Genesis spacecraft was designed to provide clues about how the Solar System formed.
© NASA/JPL/Caltech
Investigators may have discovered what caused the Genesis spacecraft to crash into the Utah desert this September. Some crucial switches were installed backwards, because of an error in the instructions.
The problem stems from the craft's design drawings, made by Lockheed Martin in 2001. They showed that some tiny cylindrical plungers, designed to detect the gravity of an incoming planet and deploy a parachute, were installed the wrong way.
There were four such switches - two as a backup in case the first two failed. But all of them had been installed backwards. As a result the parachute didn't open, and the capsule plummeted to Earth.
None of NASA's review processes picked up the mistake. "It would be very easy to mix this up," says Michael Ryschkewitsch, chair of NASA's mishap investigation board at the Goddard Space Flight Center in Greenbelt, Maryland. Investigators had to X-ray the crashed craft to confirm that the devices were the wrong way round.
This is a road we didn't want to be on.
Don Burnett
Genesis principal scientist
Good news for Stardust
The Stardust sample return mission, which is set to return to Utah in 2006 carrying a portion of a comet's tail, has the same switches as Genesis. Fortunately, that craft's designs show that they were installed correctly.
The mishap investigation board has yet to finish its work, and may yet find other problems with Genesis. A battery that overheated during the early days of the mission, and was an early suspect for the crash, has yet to be fully investigated. "The battery is going to get a lot of our attention," says Ryschkewitsch.
The Genesis mission was designed to provide clues about how the Solar System formed by capturing a few grains of material from the solar wind - a blast of charged atoms that fly from the Sun at hundreds of kilometres per second.
The capsule was so delicate that NASA planned to have it caught by helicopter stunt pilots in order to ensure a gentle landing. Instead the capsule broke apart when it slammed into the ground.
Salvage operation
Scientists are optimistic about their chances of salvaging samples from the capsule. "It's not a question of data or no data. It's a question of the precision of the data," says Don Burnett, principal scientist on Genesis and a geochemist at the California Institute of Technology, Pasadena.
I'm optimistic that contamination will not be a show-stopper.
Roger Wiens
Genesis science investigator
"Our goal was to have no more contaminant atoms than implanted solar wind atoms per square centimetre," says Burnett. This level of contamination would have made detecting the sample "feasible" says Burnett. In fact it is much worse than this in places. "We now may have to figure out how to clean up the surfaces. This is possible in principle but a road we didn't want to be on," he says.
Luckily, it rained in Utah about four days before re-entry, and this damped the dust down, says Roger Wiens, an investigator on the project at the Los Alamos National Laboratory in New Mexico.
"I'm optimistic that contamination will not be a show-stopper for nitrogen and oxygen isotopic analyses, which were priorities one and two," says Wiens. "Some of our lower priorities will fall off the table due to contamination."
The samples are now being examined at the Johnson Space Center in Houston, although it will probably be months before scientists know how much data they will be able to retrieve.
