According to the proposal, some of these tests will require fast, vertical takeoffs and landings (we’re looking at you, SpaceX and Blue Origin). Others can have a slower ascent—perhaps that’s a job for Sierra Nevada’s spaceplane. Up until now, NASA experiments would travel into space on sounding rockets or space balloons, and then float aimlessly back to Earth on parachutes–the space agency was more concerned with getting stuff up into space than getting it back to Earth. Now that SpaceX and Blue Origin have proven reusable rockets are possible, NASA is interested to see how the experiments fare during controlled landings. Although there isn’t exactly a glut of companies providing reusable rides to space, NASA puts out these calls for proposals so that everyone gets a fair shot and so that contractors can compete to provide the lowest prices for their services. [NASA via Gizmodo]