When NASA’s Opportunity rover photographed a strange Martian rock on January 8, it initiated a mystery, since that rock had not been there four days earlier. Now, the enigma has been solved. According to a NASA press release, the errant rock, dubbed Pinnacle Island, is a chunk of a bigger rock broken and dislodged by one of the rover’s wheels.
Pinnacle Island is about an inch and a half wide and resembles a jelly doughnut, with its white rim and red center. Newer images of the vicinity taken by Opportunity, after NASA moved the rover a short distance, reveal another overturned rock with the same bizarre appearance directly uphill of Pinnacle Island. Given the location of the rover’s wheel tracks, it appears that Opportunity drove over the rock, broke it, and dislodged a piece that tumbled downhill – Pinnacle Island.
Analysis of Pinnacle Island yielded high levels of water-soluble elements such as manganese and sulfur. These elements were probably concentrated in the rock by water; whether than occurred recently near the surface or long ago deeper under the surface is not known.
Now that the mystery of Pinnacle Island has been solved, the rover has endured the minimum solar-energy point of the Martian winter, and wind has shifted dust off the rover’s solar array, NASA is sending Opportunity on its way. The rover will drive south and uphill towards a boulder-strewn ridge known as the McClure-Beverlin Escarpment. There, Opportunity will examine exposed geological layers. Investigating the north-facing slope will also angle Opportunity’s solar panels towards the winter sun.
The escarpment is named after Bill McClure and Jack Beverlin, the first recipients of the NASA Medal of Exceptional Bravery. On February 14, 1969, McClure and Beverlin rescued the second Mars mission, Mariner 6, when the launch vehicle began to collapse on the pad due to loss of pressure. Opportunity has been operating on Mars since January 2004. Its twin, Spirit, lost contact with Earth in 2010.