“The Mars Exploration Rover Opportunity found evidence at a place called Meridiani Planum on Mars that liquid water once soaked the ground there...”

It provides the first evidence collected on the surface of Mars that suggests that the planet once had surface conditions that would have been suitable for some primitive forms of life.

The Mars Exploration Rover Opportunity found evidence at a place called Meridiani Planum on Mars that liquid water once soaked the ground there, and that it occasionally rose to the surface and flowed across the surface. This finding helps us understand what Mars was like in the distant past, and suggests that it was once a more suitable place for life than it is today.

I became involved in this research by writing proposals to NASA for the funding to do it. There were many obstacles along the way: several unsuccessful proposals, two failed Mars missions that preceded ours, technical problems during our spacecraft development that almost prevented us from launching the rovers, and flight to a planet where historically two-thirds of the missions that preceded ours had failed.

I think that our findings make Mars a more attractive target for exploration by robots and, eventually, by humans.

Steven W. Squyres 
Goldwin Smith Professor of Astronomy
Department of Astronomy
Cornell University
Ithaca, NY, USA