: SpaceX's next resupply mission to the International Space Station will test a system designed to safely return the booster stage to Earth. If the test is successful, it will be a major step forward in the company's plan to develop reusable rockets. The company estimates that reusable rockets could reduce the cost of spaceflight by a factor of 100. In this test, the company's Falcon 9
rocket booster will be equipped with a set of four extendable legs. After second stage separation, the booster will reignite three of its nine engines and extend the legs to control its descent. Because this is the first live test of the system, the rocket will "land" in the ocean for safety purposes.