Rebooting on Mars
It's a PC user's nightmare: You're almost done with a lengthy e-mail, or about to finish a report at the office, and the computer crashes for no apparent reason. It tries to restart but never quite finishes booting. Then it crashes again. And again.
Getting caught in such a loop is frustrating enough on Earth. But imagine what it's like when the computer is 200 million miles away on Mars. That's what mission controllers faced when the Mars rover Spirit stopped communicating last month.
Ultimately, the fix that saved Spirit wasn't that different from how a PC would be repaired on Earth. It's just that the folks who have their hardware on Mars -- and the eyes of the world on them -- are better prepared for disaster.
Tech support for an $820 million mission is a cautious affair. Tools to recover from and fix any problem must be built into the system before launch. The systems' behaviors need to be completely understood and predictable.
"Luckily, during the design period, we anticipated that we might get into a situation like this," said Glenn Reeves, who oversees the software aboard the Mars rovers Sprit and Opportunity at NASA's Jet Propulsion Laboratory.
For stability, reliability and predictability, mission designers did not bust the budget and design the hardware or software from scratch. Instead, they turned to hardware and software that's been used in space before and has a proven track record on Earth as well.
