The Mars Rover That Just Won't Die

Interesting article by William Herkewitz at Popular Mechanics, via BadBlue Car News:

The rover rolls its way across a barren red sea. It has just finished a geologic survey of Mars's massive Endeavor crater–finding more proof of the planet's watery past–and already has its eyes set on the next landmark.

No, this isn't Curiosity, the $2.5 billion dollar extra-planetary playboy that landed last August. This is Opportunity, its older, meeker, and pared-down cousin. By most measurements, Opportunity is less impressive. Well, with one exception: It will not die.

Opportunity is just a month shy of its 10-year launch anniversary, and the rover is still active. The mobile geologist has now survived its original stated mission length of 90 Martian days by three dozen times over (though that initial timeframe was charitably conservative). It has also far outlived the intended lifespan of its parts, its identical twin Spirit, and the expectations of everyone involved in the project.

"We've been on borrowed time for a while," John Callas, the project manager of the NASA Opportunity mission, said at a press conference today. "I don't think there's anyone on this planet that would have imagined this rover lasting this long when we started ten years ago." What makes Opportunity's lifespan so bizarre is that robot has always been just a step away from crisis. Many NASA projects, including the new Curiosity rover, have been engineered to be chock-full with redundant back-up mechanisms. When there's no hope of traveling to Mars to fix vital parts that break, engineers often double down on engines, processors, and other important machinery with backup system. This is usually a good move: When you have a million parts, each with a one-in-a-million chance of breaking, failure is almost assured.

Opportunity, however, lacks this redundancy. The reason is that it landed ballistically Mars, like a bullet surrounded by giant airbags (unlike Curiosity's the Mission Impossible-style "seven minutes of terror" descent.) To help it survive its landing, Opportunity was built light—stripped down to its essential equipment. "We have a single processor." Callas says. "A single power supply," When those die, Mars will lose an explorer and gain a monument. "If we have a solder joint that breaks, its game over," Callas says. "It's just instant death. … That said, the batteries are in shape, there's been no indication of anything [wrong]."

Considering all that could go wrong on a mission to Mars, the fact that Opportunity is still going strong after a decade is nothing short of amazing.