January 24, 2014
– NASA's Opportunity rover has marked ten years of Mars exploration, an extraordinary milestone that adds to the robot's growing legend.
The golf-cart-size Opportunity rover landed on the night of Jan. 24, 2004, three weeks after its twin, Spirit. Although both six-wheeled robots were originally tasked with 90-day missions, Spirit explored until 2010 and Opportunity keeps roving around the Red Planet to this day, gathering clues about Mars' warmer and wetter past.
"It's a well-made American vehicle," Spirit and Opportunity deputy principal investigator Ray Arvidson said Thursday (Jan. 23) when asked by reporters to explain Opportunity's amazing longevity.
Still, the Opportunity rover's continued productivity at such an advanced age has surprised the mission team.
"I never expected this to happen, but it is so much fun," Arvidson told SPACE.com. "It's important science and it's exploration and discovery. I'm having the time of my life."
Searching for signs of water
Artist concept of a NASA Mars Exploration Rover on the surface of the Red Planet. (NASA/JPL/Cornell University)
Ten years ago, NASA dispatched Spirit and Opportunity to search for signs of ancient water activity on Mars' surface, which is very cold and dry today.
Both rovers found plenty of such evidence at their distinct landing locations. In 2007, for example, Spirit unearthed deposits of pure silica when its crippled right front wheel dug a furrow in the red dirt. Since silica forms when hot water reacts with rocks, the area likely once had two key ingredients necessary for life as we know it — liquid water and an energy source.
And Opportunity has made its share of big discoveries as well, some of them coming quite recently. On Thursday, for instance, mission scientists announced that the rover had found signs of a potential life-supporting environment in four-billion-year-old rocks on the rim of Mars' Endeavour Crater, which Opportunity has been exploring since 2011.
"Were I there back when this material was being emplaced and altered, and I had my summer house, this is where I would drill to get good drinking water," Arvidson said. "The older you look, the better it gets in terms of habitability at this location."
Spirit's and Opportunity's discoveries helped pave the way for NASA's Curiosity rover, which landed inside Mars' Gale Crater in August 2012 to determine if the Red Planet could ever have supported microbial life.
Curiosity found a potentially habitable lake system dating from around 3.7 billion years ago, so it's possible microbial life could have survived on Mars' surface for hundreds of millions of years, though perhaps not continuously in time and space during that stretch, researchers said.
Driving well past warranty
NASA's baseline mission requirements called for the solar powered Spirit and Opportunity to drive about 0.6 miles (1 kilometer). But both rovers shattered that ceiling, just as they made a mockery of the 90-day lifespan. Spirit logged 4.8 miles (7.7 km) during its operation, while Opportunity's odometer reads 24.07 miles (38.73 km) and counting.
Map showing the path blazed during Opportunity's first decade of driving on Mars. (NASA/JPL-Caltech/MSSS/NMMNHS)
In fact, Opportunity holds the U.S. distance record for off-planet driving and is creeping up on the overall champ, the Soviet Union's remote-controlled Lunokhod 2 rover, which racked up 26 miles (42 km) on the moon in 1973.
So how have the twin Mars Exploration Rovers managed to keep performing so long after their warranties expired? While the high-quality design and construction as cited by Arvidson is a major factor as is the skill of the rover team, good fortune has also played a role, mission officials said.
For example, the rovers' handlers did not expect Martian breezes to blow the dust off the robots' solar panels on a somewhat regular basis, which has happened throughout the pair's time on the Red Planet.
"This has been a tremendous benefit, this periodic [dust] cleaning," Spirit's and Opportunity's project manager John Callas, of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said on Thursday. "We can't predict it — it seems to have some seasonal relationship — but it certainly has enabled the rovers to continue to generate power."
While Opportunity is showing some signs of its advanced age, such as an arthritic robotic arm, the rover remains in good health, Callas added.
Before-and-after images showing same patch of ground in front of the Opportunity rover taken 13 days apart documents the arrival of a bright rock onto the scene. (NASA/JPL/Cornell/Arizona State)
The robot continues to study rocks; its current focus on a strange stone that suddenly appeared in Opportunity's line of sight. Scientists believe Opportunity likely knocked this rock, which looks like a jelly donut, free of the substrate while turning its wheels. The rock appears to have landed upside down, affording a rare chance to examine material that has not been exposed to Mars' air for a long time — perhaps billions of years.
This sort of serendipity and opportunism is a hallmark of the discovery-driven mission, team members say.
"It is just a wonderful experience. Each time we move, we find something new," Arvidson told SPACE.com.
Mars rover legacy
Spirit and Opportunity are leaving an impressive legacy of science and exploration, helping researchers expand their understanding of the Red Planet, paving the way for future missions, NASA officials said.
Section of a panorama acquired in 2005 by Spirit from the top of "Husband Hill" presenting the view south. (NASA/JPL/Cornell)
"By standing on the solar panels of Spirit and Opportunity, we see the future of Mars exploration that has progressed to looking for biosignatures, the ability to cache samples for sample-return and planning for future human [missions] to Mars," Michael Meyer, lead scientist for NASA's Mars Exploration Program, said.
But the rovers have also contributed in other, less tangible ways that touch all of humanity, Callas said.
"Over the past decade, through these rovers, our species has gone to work on Mars. In addition to being earthlings, because of these rovers, we have become Martians, too — dual citizens, if you will," Callas said. "We now live in a larger world, a world that extends beyond our own home planet."
"These rovers have made Mars our neighborhood and our backyard, and this is something truly remarkable."