Dream Chaser is an American reusable lifting-body spaceplane being developed by Sierra Nevada Corporation (SNC) Space Systems. Originally intended as a crewed vehicle, the Dream Chaser Space System is set to be produced after the cargo variant, Dream Chaser Cargo System, is operational. The crewed variant is planned to carry up to seven people and cargo to and from low Earth orbit. The cargo Dream Chaser is designed to resupply the International Space Station with both pressurized and unpressurized cargo. It is intended to launch vertically on the Vulcan Centaur rocket and autonomously land horizontally on conventional runways. A proposed version to be operated by ESA would launch on an Arianespace vehicle. Spacecraft The Dream Chaser design is derived from NASA's HL-20 Personnel Launch System spaceplane concept, which in turn is descended from a series of test vehicles, including the X-20 Dyna-Soar, Northrop M2-F2, Northrop M2-F3, Northrop HL-10, Martin X-24A and X-24B, and Martin X-23 PRIME. Technology partners In 2010, the following organizations were named as technology partners for the original passenger Dream Chaser: Aerojet – reaction control system technology AdamWorks – composites Charles Stark Draper Laboratory – guidance, navigation, and control Lockheed Martin – airframe construction and human rating of the spaceplane MDA – systems engineering University of Colorado – human-rating Propulsion On-orbit propulsion of the Dream Chaser was originally proposed to be provided by twin hybrid rocket engines capable of repeated starts and throttling. At the time, SNC Space Systems was also developing a similar hybrid rocket for Virgin Galactic's SpaceShipTwo. In May 2014, SNC involvement in the SpaceShipTwo program ended. After the acquisition of Orbitec LLC in July 2014, Sierra Nevada Corporation announced a major change to the propulsion system. The hybrid rocket engine design was dropped in favor of a cluster of Orbitec's Vortex engines. The new engines would use propane and nitrous oxide as propellants. Thermal protection system Its thermal protection system (TPS) is made up of silica-based tiles (for most of the belly and upper portion of the heat shield), and a new composite material called Toughened Unipiece Fibrous Reusable Oxidation Resistant Ceramic (TUFROC) to cover the nose and leading edges. Crewed version The originally planned Dream Chaser Space System is a human-rated version designed to carry from three to seven people and cargo to orbital destinations such as the International Space Station. It was to have a built-in launch escape system and could