The Mars rover Opportunity just celebrated its tenth anniversary, and the scrappy vehicle keeps chugging along. The rover landed on Mars on January 24, 2004. Scientists expected Opportunity and its twin Spirit to work on the Martian surface for three to six months. Fast-forward ten years, and Opportunity is still gathering valuable data.
“This vehicle is so far out of warranty that nobody predicted it would still be going on its tenth anniversary,” said Dr. Ray Arvidson, the deputy principal investigator of the dual-rover mission and a professor at Washington University in St. Louis. “It’s way beyond our wildest dreams.”
Arvidson describes himself as the “science boss” who leads the science team to develop plans for Opportunity’s sequences. Opportunity continues to fire images and data back to Earth, and that information has greatly expanded the scientific knowledge of the planet’s current state and its distant past.
Still Cranking Out Discoveries
Arvidson published an article in the journal Science in January, shortly before Opportunity’s ten-year anniversary. During most of Opportunity’s time on Mars, the rover has investigated some plains. The rocks under those plains formed under an ancient lake four billion years ago that held heavily acidic, oxidizing water. It wasn’t the type of place life would develop.
Opportunity left the plains in favor of a crater rim. The clay minerals in some of the crater rims’ rocks indicated the water that ran through the area did not have the same conditions as the plains rocks.
“The water that ran through that area billions of years ago was not highly oxidizing or acidic, but you could drink it,” Arvidson said. “Those were habitable conditions.”
Even though Opportunity does not have the capability to determine if life existed in this area four billion year ago, Arvidson believes this finding points in that direction.
“Gosh, the conditions were right,” Arvidson said. “Very mild water. Sustained water flowing through the fractures.”
Mars today is cold, dry and inhospitable but it was once a much different place. Arvidson said it used to be much wetter, but it was very acidic and oxidizing. When one goes even further back in the geologic rock record, Mars looks like a much more inviting planet.
“The earliest rock record we have [shows] very mild conditions,” Arvidson said. “Probably rainfall, snowfall, water on the surface. Rivers, lakes, groundwater running through fractures. Volcanoes exploding with steam-charged magma chambers. So it was a rather different environment early, early in time.”
In addition to his work with Opportunity, Arvidson works on the team for the newer, shinier rover Curiosity which landed on Mars in 2012. He said that rover provided images of a valley that shares a striking resemblance to the California desert.
“We see plateaus. We see rocks coming off the plateaus. We see sand dunes. We see sandy valleys. We see evidence in the rocks on the cliffs for ancient riverbed rocks and some lakebed rocks,” Arvidson said. “It’s eerily like the Earth and it’s pretty exciting scientifically to come in and see those views, and it’s also just fun.”
Don’t Bet Against Opportunity
Most cars show some age after ten years of use, even after driving on paved road and getting regular maintenance. Opportunity does not have those luxuries, which makes its continued operation all the more remarkable. The golf cart sized vehicle has its dings and dents, it is covered in dust and some of its features do not work. The emission spectrometer has been gone for years. An instrument that measures iron chemistry and mineralogy is all out of the isotope it needs to emit the necessary gamma rays it requires to its job. When Opportunity was a brand new machine, some jobs would take through hours. Now, those same tasks take months. Arvidson said the robotic arm cannot rotate to the left or right.
“When we drive, it’s kind of stuck out like the pole of a fishing rod. We have to drive up to an outcrop in a particular way because the arm can only move up and,” Arvidson said. “But doggonit, it’s arthritic, it’s getting old, it’s way out of warranty, it doesn’t have redundancy, but just keeps going.
“I wouldn’t bet against this vehicle on any given day.”