Researchers concluded the doughnut-shaped Martian rock named "Pinnacle Island" is a piece of a larger rock that was broken off by the wheel of NASA's Curiosity rover.
The rock is believed to be 1.5 inches wide and is white rimmed with a red center, causing it to receive a lot of attention last month, a NASA news release reported.
"Once we moved Opportunity a short distance, after inspecting Pinnacle Island, we could see directly uphill an overturned rock that has the same unusual appearance," Opportunity Deputy Principal Investigator Ray Arvidson of Washington Universityin St. Louis, said in a news release. "We drove over it. We can see the track. That's where Pinnacle Island came from."
The region where the rock was found is mad up of manganese and sulfur, and may have been concentrated in the rock by water.
"This may have happened just beneath the surface relatively recently," Arvidson said, "or it may have happened deeper below ground longer ago and then, by serendipity, erosion stripped away material above it and made it accessible to our wheels."
The rover's next steps will be to drive south and inspect rock on a nearby slope. The rover will have to tilt its solar panels northwards to catch the winter Martian Sun.
"We are now past the minimum solar-energy point of this Martian winter," said Opportunity Project Manager John Callas of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif. "We now can expect to have more energy available each week. What's more, recent winds removed some dust from the rover's solar array. So we have higher performance from the array than the previous two winters."
The rover and NASA's Mars mission has made a number of findings suggesting wet conditions once (or do) exist on the barren Red Planet; some may have been acidic while others milder and able to support life.
