Today I was reading articles from space.com on my Palm. One article concerned the Stardust space probe which is due to come back to Earth on January 15th carrying, what else, stardust that it has collected in space.
The mission is similar to the Genesis probe which also collected space dust and returned to earth. The idea was it would re-enter the atmosphere, deploy a parachute, and then be intercepted gently by a helicopter on the way down to avoid breaking the fragile collection plates sealed inside the probe. Well, the parachutes never deployed, the helicopters couldn’t catch it, and Genesis crashed into the ground at high speed in September 2004, ruining a $264 million science experiment.
Other than “the parachutes failed to open” I had never heard what caused the accident. But they did investigate. There were switches inside the spacecraft that would trigger the release of the parachute by detecting g-forces. At three g’s (as the spacecraft first hit the atmosphere) the switch would engage but not release the parachute until the g forces rose to 30 g’s and then came back down below 3 g’s again when it would be safe for the parachutes to deploy. But the designer at Lockheed put the gravity switch in upside down so the switch saw g’s in the wrong direction and never engaged. But they’re not complete idiots: there was a backup switch. It was upside down too. No one ever caught the mistakes. It would be like putting airbags in your headrest instead of the steering wheel.
Stardust was designed by Lockheed too. Watch out for falling spacecraft on the 15th.