SpaceX's secondary mission is to reuse rockets, similarly to a plane. It first began to test reusability with a prototype called Grasshopper in 2012, as well as controlled soft landings into the water during Falcon 9 launches. In 2014, Grasshopper was replaced by F9R, which was an upgraded version of grasshopper included retractable landing gear and 3 engines, compared to Grasshopper's single engine. Falcon 9 was landed in December on a ground pad, followed by a landing on a drone ship the next year. Currently, SpaceX has landed successfully 48 boosters. Dragon capsules, as well as farings, are also being reused. Reusing parts of rockets greatly reduce costs.