X-37 space plane. Computer artwork of the robotic X-37 space plane glowing as it re-enters the Earth's atmosphere. This reusable launch vehicle (RLV) will test various technologies for space vehicles, with the goal of greatly reducing the cost of putting payloads into space. After being carried into space by a space shuttle, the X-37 will be launched from the shuttle's cargo bay. It will orbit for up to 21 days as it carries out experiments, before entering the Earth's atmosph- ere and landing. The X-37, which is over 8 metres in length and weighs about 6 tonnes, will be able to travel at up to 25 times the speed of sound. It is being co-developed by Boeing and NASA, USA.