James Wray is an assistant professor of Earth and atmospheric sciences at the Georgia Institute of Technology in Atlanta. He is a collaborator on the Curiosity rover and the Mars Reconnaissance Orbiter science teams. His research explores the chemistry, mineralogy and geology of Martian rocks as records of environmental conditions throughout the planet’s history.

In less than a month, the Opportunity rover will begin her 10th year on the surface of Mars. She has already outlived her 90-day warranty 35 times over, like a human living 2,500 years instead of 70 – an astonishing engineering achievement.

But how has Mars science advanced during this period?

Opportunity and her twin sister, Spirit, went to Mars to determine whether, where, and how liquid water ever flowed across the Martian surface. Before their missions, we knew Mars had dry river valleys, but how could we be sure that water carved them? Where were the minerals that liquid water leaves behind: the clays that dominate our tropical soils on Earth, or salts deposited after evaporation?

Opportunity landed on Mars and opened her robotic eyes to a paradise of salt-rich rocks, with the frozen ripples of 3-billion-year-old ponds confirming that water once was there. But as the years passed on, like any Eden, the paradise felt more like a prison, and a heretical plan emerged to journey a seemingly impossible distance in pursuit of new knowledge.
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