Mars Exploration Rovers: 10 years

Scientists are baffled by the sudden appearance of a jelly doughnut-like rock that the Opportunity rover spotted in January 2014. These are images of the same location; the rock on the right was not there 12 days earlier. Researchers now believe the rover's wheels flicked the rock into its current spot.

Scientists are baffled by the sudden appearance of a jelly doughnut-like rock that the Opportunity rover spotted in January 2014. These are images of the same location; the rock on the right was not there 12 days earlier. Researchers now believe the rover's wheels flicked the rock into its current spot.