The Mars rover Curiosity has become an international celebrity since landing on the planet in August 2012. In the meantime, the senior NASA rover on the Martian surface, Opportunity, is quietly preparing to tuck in for its fifth winter on the Red Planet.
Opportunity is studying an area that the scientific team at NASA’s Jet Propulsion Laboratory (JPL) has dubbed Solander Point. Two very different rock layers join up at this point, and Opportunity will spend a winter there trying to determine what the site reveals about Mars’ geologic history.
Since it landed on Mars in January 2004, Opportunity has survived five Martian winters, which occur less frequently than on Earth because of the planet’s slower orbit around the sun. Opportunity is now heading for a spot on a northern slope where the rover’s solar panels will be tilted toward the winter sun, providing an important boost in available power.
“We know we could be on that north-facing slope with a one-day drive, but we don’t need to go there yet,” said Opportunity project scientist Matt Golombek at JPL in California. “We have time to investigate the contact between the two geological units around the base of Solander Point. Geologists love contacts.”
The geological contact that Opportunity is now investigating is a site known as Burns Formation, which includes sulfate-bearing minerals providing evidence of an ancient environment containing sulfuric acid. This formation borders older rocks, uplifted by the impact that formed a nearby crater. Observations by Mars orbiters and Opportunity’s work elsewhere on the surface suggest to researchers that the older rocks may contain minerals that formed under wet and less acidic conditions.
The team plans to get Opportunity onto the north-facing slope before mid-December, though the team expects to keep the rover mobile through the winter. Daily sunshine for the rover will reach a winter minimum in February 2014. Solander Point offers rock outcrops for the rover to continue studying through the winter months.
Opportunity and its twin rover Spirit both completed their three-month prime missions in April 2004. These planetary explorers found evidence within only a few months of landing that a wet environment had existed on Mars in the past.
After that, Opportunity and Spirit conducted years’ worth of extended missions. Spirit ceased operations during its fourth Martian winter, in 2010. Opportunity shows symptoms of aging, such as loss of motion in some joints, but continues to accomplish exploration and science.