The Mars Exploration Rover (MER) mission has sent back groundbreaking information about the history of Mars. The most important result is the discovery of salt deposits that indicate that some regions of the planet were once “drenched” in water. These findings bolster the notion that, at least in its distant past, Mars was a habitable world. But preparing the rovers for launch was an arduous and exhausting marathon. In a recent talk given at a NASA symposium on risk management in Monterey, California, MER Principal Investigator Steve Squyres explained how the mission team made it to the finish line.