Suborbital spaceplanes fly lower energy trajectories that do not put as much stress on the spacecraft thermal protection system. For example, the Space Shuttle thermal protection system (TPS) protects the orbiter's interior structure from surface temperatures that reach as high as 1,650 ☌ (3,000 ☏), well above the melting point of steel. Orbital spacecraft reentering the Earth's atmosphere must shed significant velocity, resulting in extreme heating. Various gases, including helium for pressurization and nitrogen for life support, were stored under high pressure in composite overwrapped pressure vessels.īuran spaceplane rear showing rocket engine nozzles, attitude control thrusters, aerodynamic surfaces, and heat shielding These engines used toxic hypergolic propellants that required special handling precautions. The Space Shuttle used dedicated engines to accomplish orbital maneuvers. This is in addition to accomplishing the task the spaceplane was launched to complete, such as satellite deployment or science experiments. On-orbit thermal and radiological environments impose additional stresses. Once on-orbit, a spaceplane must be supplied with power by solar panels and batteries or fuel cells, maneuvered in space, kept in thermal equilibrium, oriented, and communicated with. In any case, the Challenger disaster demonstrated that the Space Shuttle lacked survivability on ascent.

The Space Shuttle was far too big and heavy for this approach to be viable, resulting in a number of abort modes that may or may not have been survivable. If the launch vehicle suffers a catastrophic malfunction, a conventional capsule spacecraft is propelled to safety by a launch escape system. The flight trajectory required to reach orbit results in significant aerodynamic loads, vibrations, and accelerations, all of which have to be withstood by the vehicle structure. The following sections will draw heavily on the US Space Shuttle as the biggest, deadliest, most complex, most expensive, most flown, and only crewed orbital spaceplane, but other designs have been successfully flown. These requirements drive up the complexity, risk, dry mass, and cost of spaceplane designs. Spaceplanes must operate in space, like traditional spacecraft, but also must be capable of atmospheric flight, like an aircraft. Landing of Space Shuttle Atlantis, a crewed orbital spaceplane Many more spaceplanes have been proposed, but none have reached flight status.Īt least two suborbital rocket-powered aircraft have been launched horizontally into sub-orbital spaceflight from an airborne carrier aircraft before rocketing beyond the Kármán line: the X-15 and SpaceShipOne. Consequently, heavy heat shielding is required during reentry as this kinetic energy is shed in the form of heat. Orbital spaceflight takes place at high velocities, with orbital kinetic energies typically at least 50 times greater than suborbital trajectories. As of 2019 all past, current, and planned orbital vehicles launch vertically on a separate rocket. Another, Dream Chaser, is under development in the U.S. All spaceplanes to date have been rocket-powered but then landed as unpowered gliders.įour types of spaceplanes have successfully launched to orbit, reentered Earth's atmosphere, and landed: the U.S. Orbital spaceplanes tend to be more similar to conventional spacecraft, while sub-orbital spaceplanes tend to be more similar to fixed-wing aircraft. To do so, spaceplanes must incorporate features of both aircraft and spacecraft. A spaceplane is a vehicle that can fly and glide like an aircraft in Earth's atmosphere and maneuver like a spacecraft in outer space.

Planes skipper