The American space shuttle is at present the only operating spaceplane, a winged craft that is part rocket, part aircraft. It takes off like a rocket, but behaves as an aircraft when it returns to the Earth from space. The Russians have developed a similar craft, Buran, but as yet it has flown into orbit only once, and that flight was unmanned. By the end of the century, however, the shuttle might not be the only spaceplane shuttling back and forth into space and back. NASA itself is developing a national aerospace plane (NASP). The European Space Agency (ESA) has on the drawing board a spaceplane called Hermes; German designers have suggested another one, called Sanger. The Russians have a spaceplane called Max; and British Aerospace has one called Hotol. The development of the NASP was approved by President Reagan, who in his State of the Union address to Congress in 1986, referred to it as the 'Orient Express', capable of whisking passengers from New York to Tokyo is just two hours. The initial phase of development hinges on building a prototype craft, designated the X-30. NASA give the X designation to experimental rocket craft, such as the X-15, which pioneered hypersonic aerospace research in the 1950s and 1960s. The X-30 will be built of ultralightweight materials, but its most revolutionary feature will be its engines, known as scramjets (supersonic combustion ramjets). These engines will be dual purpose, able to act as jets during flight through the atmosphere and as rockets on the fringes of space. During launch, they scoop in air from the atmosphere which contains the oxygen to burn their hydrogen fuel. When they reach the fringes of space, where the air is too thin, they switch over to on-board liquid oxygen for the final thrust into orbit. The British Aerospace spaceplane (horizontal take-off and landing) spaceplane has a similar type of engine. Like the X-30, it is designed to take off on a runway like an ordinary plane. Alternatively, it could be air-launched, having been carried to high altitude by a conventional heavy aircraft. The Russian Antonov-225 heavy transport plane would be a likely candidate for the job. The AN-225 also features in the Russian plan for an alternative spaceplane, called Max (formerly, the multipurpose aerospace system). It takes the form of a mini shuttle with three engines, which takes its propellants from a bulbous tank, rather like the shuttle's external tank. The tank is jettisoned shortly before the craft reaches orbit. Uniquely, the engines use three propellants, liquid hydrogen, liquid oxygen and kerosene. ESA's Hermes, is an entirely different kind of craft, designed to be lifted into orbit by the Ariane 5 rocket, now under development. On a typical mission, it would ferry European astronauts to space station Freedom. Hermes is a type of craft known as a lifting body, similar to designs NASA tried out in the 1960s when researching high-speed re-entry conditions. It has delta wings with upturned winglets. Hermes rides into orbit mated with a resource module, which carries a docking hatch and an airlock. This module is jettisoned prior to re-entry, which is unpowered. Hermes would land on an ordinary runway. NASA is also currently researching a similar type of craft, called the HL-20. This craft is conceived as a space taxi, designed to ferry crews but not cargo to and from space station Freedom. It would also be available as a CERV (crew emergency return vehicle), also called an ACRV (assured crew return vehicle). The HL-20 would be launched, like Hermes, by an expendable launch vehicle, such as the Titan 4, or maybe by carrier aircraft followed by expendable booster.
