Ninety Days Become Fourteen Years on Mars

Opportunity arrived on Mars in January 2004 with a mission planned for ninety Martian days. It landed inside a small crater, close to an exposed outcrop that immediately gave its science team something valuable to inspect. The rover had not crossed a desert to find its first geological target. It had effectively landed beside one. Over the following fourteen years, that fortunate beginning became a much larger investigation.

The mission’s central question concerned water. Liquid water leaves traces in the minerals, textures and arrangement of rocks, even after the water itself has disappeared. Opportunity carried cameras and instruments that could examine those traces. Its job was not to photograph a present-day river or find an organism. It was to work out what kinds of conditions had existed in a place that now looked dry and hostile.