Opportunity rover to explore Martian gully
NASA’s Mars rover Opportunity will drive down an ancient Martian gully carved by a fluid that may have been water. The rover will also visit, for the first time, the interior of the crater that it has been working beside for the last five years. The new destinations are part of a two-year extended mission that began Oct. 1, the latest in a series extensions that started at the end of the rover’s prime mission in April 2004. Opportunity landed on Mars on Jan. 24, 2004, on a planned mission of 90 Martian days, which is equivalent to 92.4 Earth days.
“We have now exceeded the prime-mission duration by a factor of 50,” noted Opportunity Project Manager John Callas of NASA’s Jet Propulsion Laboratory, Pasadena, California. “Milestones like this are reminders of the historic achievements made possible by the dedicated people entrusted to build and operate this national asset for exploring Mars.”
Opportunity started its extended mission in the Bitterroot Valley portion of the western rim of Endeavour Crater – a basin 14 miles (22 kilometers) in diameter that was excavated by a meteor impact billions of years ago. Opportunity reached the edge of the crater in 2011, after over 7 years exploring a number of smaller craters, where the rover discovered evidence of ancient acidic water that soaked underground layers and periodically covered the surface.
The gully that is Opportunity’s next major destination is about as long as two football fields and slices west-to-east through the rim of Endeavour Crater. It is about half-a-mile (less than a kilometer) south of the rover’s current location.
“We are confident this is a fluid-carved gully, and that water was involved,” said Opportunity Principal Investigator Steve Squyres of Cornell University, Ithaca, New York. “Fluid-carved gullies on Mars have been seen from orbit since the 1970s, but none had been examined up close on the surface before. One of the three main objectives of our new mission extension is to investigate this gully. We hope to learn whether the fluid was a debris flow, with lots of rubble lubricated by water, or a flow with mostly water and less other material.”
The Opportunity mission team plans to drive the rover down the full length of the gully and onto the crater floor. The extended mission’s second goal is to compare rocks found inside the crater to the types of rocks Opportunity studied on the plains it explored before reaching Endeavour.
“We may find that the sulfate-rich rocks we’ve seen outside the crater are not the same inside,” Squyres said. “We believe these sulfate-rich rocks formed from a water-related process, and water flows downhill. The watery environment deep inside the crater may have been different from outside on the plain – maybe different timing, maybe different chemistry.”
Keeping Opportunity active for the next two years could prove to be a challenge for the team. While most of the rover’s mechanisms are still functioning well, its motors and other components have far exceeded their life expectancy. Opportunity’s twin, Spirit, succumbed to the cold of its fourth Martian winter in 2010 after losing the use of two of its wheels. Opportunity will face its eighth Martian winter in 2017.
During the two-year mission extension that ended last month, Opportunity drove through the “Marathon Valley” area of Endeavour’s western rim, studying the geological context of water-related minerals discovered by orbital observations. Last month, the rover drove through “Lewis and Clark Gap” – a low part in the wall separating Marathon Valley and Bitterroot Valley.
The week, Opportunity is studying rock formations near “Spirit Mound“ – a prominent feature near the east end of Bitterroot Valley. The third major goal of the extended mission is to find and study rocks that were in place before the impact that excavated Endeavour Crater. It is not yet known whether the mound area has rocks that are that ancient.
Jim Sharkey is a lab assistant, writer and general science enthusiast who grew up in Enid, Oklahoma, the hometown of Skylab and Shuttle astronaut Owen K. Garriott. As a young Star Trek fan he participated in the letter-writing campaign which resulted in the space shuttle prototype being named Enterprise. While his academic studies have ranged from psychology and archaeology to biology, he has never lost his passion for space exploration. Jim began blogging about science, science fiction and futurism in 2004. Jim resides in the San Francisco Bay area and has attended NASA Socials for the Mars Science Laboratory Curiosity rover landing and the NASA LADEE lunar orbiter launch.