It Wasn't Supposed To Last This Long...

NASAArtist concept of the Opportunity rover

The mission wasn't supposed to last more than 90 days. But 10 years later, NASA's Opportunity rover is still in good health and continues to send back data from Mars.

The prolonged health of the rover "was not in anyone's wildest dreams," John L. Callas, a project manager for the Mars Exploration Rover mission, wrote in an editorial for Space.com.

Opportunity launched on July 7, 2003. The golf-cart-sized robot landed on Mars on Jan. 24, 2004, Pacific Time.

Its identical twin, Spirit, touched down on the other side of Red Planet a couple of weeks earlier, but stopped talking to Earth in 2010, around six years into its mission.

So why has the Opportunity rover been able to outlast its designed lifetime by thousands of days? On its website, NASA attributes the robot's staying power to "a combination of sturdy construction, creative solutions for operating the rovers and even a little luck!"

"It's a well-made American vehicle," Ray Arvidson, the rover's lead investigator was quoted by The Register as saying. "These are excellent machines, they are well designed, they're well built, they're fantastic and that's why they're still working."

Mars is no vacation spot. The ground is covered with sharp rocks and steep hills, dirt tornadoes whirl around the surface, and the planet goes through wild temperature swings - from 80 degrees in the Martian summer to as low as -199 degrees in the winter.

NASAThe rover's design allows it to tilt up to 45 degrees in any direction without tipping over.

When tackling rough terrain, the rover doesn't topple over on its six wheels because of a "rocker-bogie" suspension system that was designed for stability. You can see a good explanation of how the rocker-bogie works here.

Heaters in the body of the unit help batteries and other temperature-sensitive equipment to continue operating in the bitter-cold.

In addition, scientists originally thought that all of the Martian dust blowing around would coat the robot's solar panels, rendering them unusable within a few months. Instead, strong winds have helped to keep the panels relatively clean.

Callas agrees that rover's success is due to both human ingenuity and factors that are beyond our own comprehension:

We can assert that unexpected wind gusts blew the dust off the solar arrays to maintain rover power. We can claim that operational skill permitted the rovers to survive the cold, dark Martian winters. We can pride ourselves that we built exquisite roving machines.

All of these are true. But does that really explain this unimagined longevity and the tremendous scientific success? Whatever the explanation, this is a grand accomplishment.

The prime mission of both rovers was to search for geological clues about environmental conditions on early Mars - like evidence of water - and to determine whether those conditions would have been suitable for life. By looking for rocks and soil types that typically form in water, both rovers confirmed that streams, lakes, or rivers once flowed on Mars.

NASAThe 'Greeley Panorama' from Opportunity's fifth Martian winter.

To date, Opportunity rover has driven about 24 miles and snapped more than 170,000 images. While she's still running, the rover is starting to feel the effects of old age - two of the robot's 10 instruments have stopped working and its robotic arm has become "arthritic," Callas wrote.

Opportunity is currently stationed at the edge of an exposed outcrop on the rim of Endeavor Crater, where satellite observations suggest that small amounts of clay minerals might be present.

The aging rover is also continuing to investigate a mysterious jelly-doughnut-shaped rock that appeared in pictures of the same patch of ground taken 13 days apart. Scientists think the rock was probably flicked into its new position by one of the rover's wheels as the machine was turning around. The rock, which has a white rim and center that is deep red, unlike anything scientists have seen before on Mars.