NASA’s Opportunity rover has gone back to work after a two week delay because a pebble was jamming its rock abrasion tool. The pebble fell out of the tool on its own just before engineers tried reversing its motor to kick it out. Opportunity demonstrated that everything was working fine by cleaning off a rock inside “Endurance Crater” with its wire brush. Mars and Earth are approaching “conjunction”, where the Sun lies directly in between our planets, so controllers will be unable to communicate with the rovers for several days.