NASA’s Opportunity Mars rover on walkabout near crater rim
NASA’s Opportunity Mars rover is investigating rocks near the rim of Endeavour Crater for signs that they were either transported by a flood or eroded in place by the Martian wind. These are two of several possible explanations for features observed the crater rim’s crest above “Perseverance Valley”, which is carved into the inner slope of the crater’s rim.
Once Opportunity completes its “walkabout” survey of the area, the rover team will drive it down Perseverance Valley. Opportunity’s drives now use steering motors on only the rear wheels, due to a temporary jam of the left-front wheel’s steering actuator earlier this month. The rover has not used its right-front wheel’s steering actuator since 2005.
“The walkabout is designed to look at what’s just above Perseverance Valley,” said Opportunity Deputy Principal Investigator Ray Arvidson of Washington University in St. Louis. “We see a pattern of striations running east-west outside the crest of the rim.”
There is a broad notch in part of the crest at the top of Perseverance Valley. Just west of the notch, elongated patches of rock line the sides of a slightly depressed, east-west strip of ground which may have had a drainage channel billions of years ago.
“We want to determine whether these are in-place rocks or transported rocks,” Arvidson said. “One possibility is that this site was the end of a catchment where a lake was perched against the outside of the crater rim. A flood might have brought in the rocks, breached the rim and overflowed into the crater, carving the valley down the inner side of the rim. Another possibility is that the area was fractured by the impact that created Endeavour Crater, then rock dikes filled the fractures, and we’re seeing effects of wind erosion on those filled fractures.”
Investigation of the piles of rock along the edges of the possible channel may help scientists evaluate these and other possible histories of the area. The Opportunity team is currently studying stereo images of Perseverance Valley to plot the rover’s route. The valley extends about the length of two football fields, at a slope of about 15 to 17 degrees.
The steering actuator for Opportunity’s left from wheel stalled with the wheel turned outward more than 30 degrees on June 4. On June 17, diagnostic testing succeeded in straightening out the left front wheel.
“For at least the immediate future, we don’t plan to use either front wheel for steering,” said Opportunity Project Manager John Callas of NASA’s Jet Propulsion Laboratory (JPL), Pasadena, California. “We can steer with two wheels, just like a car except it’s the rear wheels. We’re doing exactly what we should be doing, which is to wear out the rover doing productive work – to utilize every capability of the vehicle in the exploration of Mars.
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.