How did SpaceX relaunch and land a used rocket?
Elon Musk-led space exploration startup SpaceX on Friday successfully launched and landed its pre-used Falcon 9 rocket, marking the first reuse of an orbital class rocket. SpaceX used a technique which involves firing the rocket's engines in the opposite direction at speeds greater than sound. Fuel leftover from launch is used to reignite the engine to make a landing.