Today, SpaceX launched a rocket that had already been used once before, becoming only the second rocket ever to fly twice. Even more impressively, the rocket successfully landed again, after withstanding much higher heat than the first rocket.

　　According to CEO of SpaceX Elon Musk, this particular mission required an unusually high amount of thrust, meaning that the rocket was going fast. The first stage--the booster stage, and the part of the rocket that lands and is launched again--had to carry a satellite into geostationary transfer orbit, which required almost all of its fuel on the initial takeoff. Then, it had to flip over and navigate down onto a droneship in the Atlantic Ocean, off the coast of Florida.

　　The view from the droneship after the rocket's successful landing.Upon re-entry into the atmosphere, this rocket underwent the highest force and heat ever during a SpaceX landing attempt. It landed hard on the deck of the droneship, which used up most of its emergency crush core system--the structural system designed to withstand landing shock. But it was nonetheless successfully recovered, and Musk said that the core could be replaced in a couple of hours.

　　For the short history of spaceflight, it's been normal for rockets to be used once and then lost. Certain parts of rockets, like solid fuel boosters and capsules, have been recovered, but to relaunch an entire rocket was unthinkable only a few years ago. SpaceX achieved the first-ever relaunch of an orbital-class rocket last month, which you can watch here.