A jelly doughnut-shaped rock that mysteriously appeared next to NASA’s Martian rover was actually broken and displaced by the rover itself – when it drove over the rock.
The rock caused a stir last month when it appeared in an image taken by Opportunity on January 8 in a spot where none was present just four days earlier. Scientists theorized that the rock, dubbed "Pinnacle Island," was somehow kicked up by the rover at the time, although more far-stretching ideas suggested that a small meteorite impact could be behind it.
Now the rover team confirmed that the most obvious explanation was right. The rock had been hit by Opportunity wheel slightly uphill and went down, Planetary Science Institute said in a statement.
"Once we moved Opportunity a short distance away after inspecting Pinnacle Island, we could see directly uphill an overturned rock that has the same unusual appearance," said Opportunity Deputy Principal Investigator Ray Arvidson of Washington University in St. Louis, Mo. "We drove over it. We can see the track. That's where Pinnacle Island came from."
The discovery follows analysis of the images by the team, which helped them to pinpoint the appearance of the rock to only 4 sols, or Martian days, and determine which of the rover’s movements could have disturbed it.
With the rock riddle finally solved, the team plans to drive Opportunity farther south and uphill to investigate exposed rock layers on the slope, the report said.
The Pinnacle Island mystery caused quite an upheaval among some Mars-watchers, who thought it might indicate presence of alien life there. One astrobiologist even filed a lawsuit against NASA in a bid to make it reveal more data on the rock discovery.