Elon Musk wants to go to Mars.
He has said, famously, that he wants to die on Mars, just not on impact. A technology that might help prevent such a mishap passed a crucial test one night last December, when a Falcon 9 rocket built by Musk’s company SpaceX lifted off from Cape Canaveral in Florida, carrying 11 communications satellites.
A few minutes into the flight the booster separated from the rest of the rocket, as thousands of spent boosters have done since the dawn of the space age; normally they burn up in the atmosphere, and their fragments rain into the ocean. But this booster wasn’t spent. Instead of falling, it flipped over, and its engines reignited to slow and guide its descent toward a nearby landing pad. Essentially it flew backward. From the ground it looked as if the launch movie were being rewound.