- However, the US space agency’s replacement for this vehicle, Orion, returned to the conical capsule design familiar from the Apollo missions.
- This was because Nasa intended that this newer craft be used for exploring targets in deep space, such as the Moon.
- A runway also allows ground support crews and infrastructure to be ready at the landing location.
Cost and complexity
But spaceplanes are more complex and heavier than an equivalent capsule. The winged body shape poses a particular challenge for designing thermal protection systems (TPS) – the heat-resistant materials that protect the craft from scorching temperatures on re-entry. These additional costs mean it’s impractical to design a spaceplane for a single flight. They need to be used again and again to be viable.
- A military spaceplane project called Dyna-Soar was started in the US in 1957, then cancelled just after construction started.
- Other space agencies invested in the 1980s and 1990s, in Europe, with the Hermes spaceplane, and Japan, with the HOPE vehicle.
- Both programmes were cancelled in large part because of cost.
Feeling the heat
- Spaceplanes have specific requirements for the final part of their journeys – as they return from space.
- A blunt nose design (where the edge of the spacecraft is rounded) is an ideal shape because it reduces build-up of heat at the foremost part of the vehicle.
- The space shuttle TPS included ceramic tiles that were especially heat resistant and a reinforced carbon-carbon matrix that was capable of withstanding temperatures as high as 2400°C.
- This resulted from a piece of insulating foam flying off the shuttle’s external tank during Columbia’s launch and hitting the wing.
Current vehicles
- Little information is available on China’s Shenlong, but the US military’s X-37B is better known.
- The ability to return comparatively fragile cargo to the surface because of a softer landing is a key capability.
Future developments
- However, concepts such as the Skylon vehicle are leading to technical developments that could eventually support development of an SSTO craft.
- For the foreseeable future, spaceplanes look promising for the following reasons: new design techniques, improved materials for the TPS, advanced computer modelling and simulation tools for optimising different aspects of design and flight parameters and continuous improvements in propulsion systems.
- Given that several governments, space agencies, and private companies worldwide are investing heavily in spaceplane research and development, we could see a future where flights with these vehicles become routine.
The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.