George W. Bush’s NASA chief, Sean O’Keefe, came into office with some serious problems to solve. The International Space Station had a cost overrun of billions. O’Keefe brought an accounting eye to the agency; in a previous job at the Defense Department, he’d been known as the “Grim Reaper.” Several years after cutting costs at NASA, O’Keefe received another directive from the President: restructure further to prioritize a mission to Mars.