Airplanes in Space?

A vehicle that can take off, fly and land like an airplane, but also travel in space is "the holy grail" of aeronautics.

THE GIST

- A British company is working on a spaceplane that can carry cargo or a pod for passengers to orbit.

- A critical piece of technology for the spaceplane's engines is currently under development.

- The spaceplane could ferry cargo and passengers into space more cheaply than current alternatives.

A British firm is upping the ante in a long-held dream to build an airplane that also can fly in space.

With support from the U.K. Space Agency, Reaction Engines is building a prototype of a critical piece of its spaceplane's technology, which will be tested on a conventional jet engine.

The ultimate goal is Skylon, an unpiloted, air-breathing vehicle that takes off and lands on a runway, and can travel beyond Earth's atmosphere.

Rather than using expensive rocket motors that have to be discarded or refurbished after every flight, Skylon is powered by two hybrid engines that can use oxygen from the air when available or liquid oxygen when there is no air. Its propellant is liquid hydrogen.

"It's the holy grail of aeronautics," said Richard Varvill, Reaction Engines technical director and a company co-founder.

The company figures a launch would cost about $10 million, compared to about $150 million for a rocket launch today. Skylon is being designed to carry cargo and satellites into orbit, but it can be adapted to fly a pod for passengers as well.

So far, seven private citizens have flown in space aboard Russian Soyuz capsules at a cost of $25 million to $40 million per seat. A commercial suborbital spaceship owned by Virgin Galactic is under development, with service expected to begin in late 2011 or 2012. Tickets for suborbital rides, which will put people above the atmosphere for about five minutes, sell for $200,000.

"If you're able to access space cheaply and safely, there are a lot of applications that will flow back. But at the moment, it's completely impractical," Varvill told Discovery News.

Reaction Engines is focusing on a critical piece of technology called a heat exchanger, needed to rapidly cool the air before it can be used by the spaceplane's engines.

"It allows the air to be compressed to higher pressures than what has been done previously," Varvill told Discovery News.

"They've already built subscale pieces and tested it in the lab, so now they're moving on to a demonstration at a very large scale. The key is making it light enough to be on an engine," added Dave Parker, director of space science and exploration at the U.K. Space Agency.

The project is far enough along that last month the British space agency hosted a workshop to introduce Skylon to engineers and managers from the United States, Japan, Russia, Europe and elsewhere.

Skylon's founders were part of a British Aerospace-Rolls Royce spaceplane project in the 1980s called HOTOL -- short for Horizontal Take Off and Landing, which was to be completely reusable.

"These are not people who started this last week," Parker told Discovery News. "They've been gnawing away at the problem for 20 years now. These are serious engineers."