Before NASA sends astronauts to live on the moon in 2020, per presidential mandate, the agency must first figure out what resources the lunar neighborhood has to offer. Are there stores of ice that could be melted and processed to provide oxygen to breathe and hydrogen for rocket fuel? Or is the potential fuel locked up inside rocks?

Aerospace engineer David Graham and his three colleagues had a deadline, and a little brown tortoise was putting it in jeopardy. In a few hours, as the sun rose over the Mojave Desert on an August morning last year, two Northrop Grumman F-5E fighter jets would come racing over the horizon. Flying 30,000 feet above Harper Dry Lake and traveling at 920 mph, the airplanes would be trailing long sonic boomsthe distinctive aural signatures of supersonic flight that ordinarily make high-speed passages over land impossible.