Sabre rocket engine could open up access to space as never before


An artist
The Skylon spaceplane would operate from a normal runway, just like any other aircraft. Photograph: Reaction Engines Ltd





By building reusable spaceplanes, the cost of reaching orbit could be reduced to a twentieth current levels. That makes spaceplanes a game changer both for taking astronauts into space and for deploying satellites and space probes.

If all goes to plan, the first test flights could happen in 2019, and Skylon – Reaction Engines' spaceplane – could be visiting the International Space Station by 2022. It will carry 15 tonnes of cargo on each trip. That's almost twice the amount of cargo that the European Space Agency's ATV vehicle can carry.

Traditional rockets can only reach orbit by dropping off empty fuel tanks as they go. This makes them virtually impossible to re-use because even if you could collect all the parts, they would need so much refurbishment and reassembly that it's usually quicker, easier and cheaper to build new ones.

Rockets are cumbersome because not only must they carry fuel, they also need an oxidising agent to make it burn. This is usually oxygen, which is stored as a liquid in separate tanks. Spaceplanes do away with the need for carrying most of the oxidiser by using air from the atmosphere during the initial stages of their flight.

This is how a traditional jet engine works, and making a super-efficient version has been engineer Alan Bond's goal for decades. In 1989, he founded Reaction Engines and has painstakingly developed the Sabre engine, which stands for Synergetic Air-Breathing Rocket Engines.

In late 2012, tests managed by the European Space Agency showed that the key pieces of technology needed for Sabre worked. No one else has managed to successfully develop such a technology.

This makes Sabre a world-leading technology and the new money will allow a full-size prototype to be made as a final test before commercial production can begin.

To reach orbit, Skylon will use Sabre to boost it to Mach 5. It will then close the air intakes and use a small amount of onboard oxidiser to turn the jets into rockets and boost itself to Mach 22. At this speed, roughly 7.5km/s, the craft will reach low earth orbit.

Used terrestrially, an aeroplane powered by Sabre engines could whiz you from the UK to Australia in just four hours, the same time it takes holidaying Brits to reach the Canary Islands.

The aeroplane version of Skylon in flight.
Using Sabre engine in an aeroplane could slash travel times around the world. Photograph: Reaction Engines Ltd

Spaceplanes should not to be confused with space tourism vehicles such as Virgin Galactic's Space Ship Two. The highest altitude this vehicle will reach is about 110km, giving passengers about six minutes of weightlessness as the craft plummets back to Earth before the controlled landing.

Although there is no fully agreed definition, space starts at around 100km in altitude. To have any hope of staying in orbit, you would have to reach twice that altitude. The International Space Station orbits at 340 kilometres, whereas the Hubble Space Telescope sits at 595 kilometres.

On the Reaction Engines recruitment web page, the company offers potential employees the chance to "join the organisation that will conceivably have the biggest impact on the aerospace propulsion industry since [inventor of the jet engine] Sir Frank Whittle's original design."

I think that might actually be an understatement. The Sabre engine could open up our access to space as never before.

Stuart Clark is the author of The Day Without Yesterday (Polygon). Find him on Twitter as @DrStuClark