Shuttles could soon be launched into space by 'beaming' power to them using microwaves.

The radical engine has completed its first tests, and found to provide enough power to launch a spacecraft.

By not having to carry fuel, craft can be far lighter at launch, and could be reused far more easily, the firm behind the concept says.

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The radical craft would be powered by microwave energy delivered wirelessly to a heat exchanger on the spaceplane, via a phased array of microwave antennas located on the ground.

HOW IT WORKS It plans to use microwave energy delivered wirelessly to a heat exchanger on the spaceplane during the entire ascent via a phased array of microwave antennas located on the ground. Instead of chemical combustion, Escape Dynamics' spaceplane will be propelled by ejecting hydrogen, heated with the microwave energy, as it flows through the heat exchanger and will be exhausted through the nozzle creating thrust. Advertisement

Escape Dynamics says it has successfully tested a thruster powered by beamed high power microwave energy, with performance greatly surpassing the limit of chemical combustion rockets.

It plans to use microwave energy delivered wirelessly to a heat exchanger on the spaceplane during the entire ascent via a phased array of microwave antennas located on the ground.

Instead of chemical combustion, Escape Dynamics' spaceplane will be propelled by ejecting hydrogen, heated with the microwave energy, as it flows through the heat exchanger and will be exhausted through the nozzle creating thrust.

After the spaceplane reaches orbit and deploys the payload, it will glide back to the launch pad, refuel, and will be ready for its next flight.

'With this technology, we can uniquely bring to market reusable, single-stage-to-orbit spaceplanes, and aircraft-like operations to orbit, and significantly decrease the cost of access to space for payloads up to 200 kg', said Laetitia Garriott, the president of the firm.

Specific Impulse (or Isp) is a measure of rocket or jet engine efficiency, much like miles-per-gallon for cars.

While chemical rockets top out at around 460 seconds Isp, static thrust tests conducted in the company's lab in Colorado using helium demonstrated an Isp above 500 seconds.

BEAMING POWER TO SPACECRAFT The externally powered launch vehicles represent a revolutionary improvement in efficiency compared to chemical rockets used today. In a typical chemical rocket powered with combustion, approximately 90% of the initial mass is allocated to propellant and only 10% is split between useful payload and structure. The small percentage of mass dedicated to structure makes chemical rockets very risky, with ~4% failure rate, and renders reusability extremely challenging. The fundamental limitation of chemical combustion makes rockets prohibitively expensive with prices ranging from $5,000-50,000 per kg of payload delivered into orbit and significantly limits the opportunities for large scale exploration of space. EDI's external propulsion launch system will operate at a specific impulse above 750 s and this breakthrough increase in efficiency reduces the fraction of mass dedicated to propellant to less than 72%. The increase of 3x in the mass fraction dedicated to structure and payload for the first time opens doors for reusability and single-stage-to-orbit flight. The firm says its first generation vehicle is optimized for 100-200 kg payloads and is designed to operate like an airplane: the vehicle flies into orbit, delivers the payload, re-enters the atmosphere after completing one or more orbits around Earth and lands back at the spaceport. Advertisement

Had hydrogen been used instead of helium, the specific impulse achieved would have been above the 600 seconds threshold required for single-stage-to-orbit operations of a launch vehicle, which is not possible with chemical rockets.

'Our recent tests are a major step forward in the continued advancement of our externally-powered high Isp thruster and validation of our efforts to change the manner of orbital launches' said Richard F. Schaden, co-founder and Chairman of the Board of Escape Dynamics. Dr. Dmitriy Tseliakhovich, CEO/CTO said.

'We, for the first time, conclusively demonstrated that a new propulsion technology that goes beyond chemical rockets and that can be used for orbital launch works on a lab scale, and we are confident that we can take it to multi-megawatt scales and eventually introduce it into single-stage-to-orbit spaceplanes that will change the way we reach orbit.'

Will Marshall, CEO of Planet Labs, said: 'Currently, small satellite payloads cost approx. $25,000-50,000 per kilo to launch, and must share a launcher with other satellites.

'I'm very supportive of efforts to create lower cost and more regular access to space. Escape Dynamics is pursuing a radical technology — one I fundamentally think is a good idea — which could massively reduce the costs for small satellite payloads.'

Escape Dynamics' recent tests demonstrated a full sequence of operation of an externally-powered propulsion system.

Energy was drawn from the electric grid, converted into microwaves using a gyrotron, guided through a system of beam shaping mirrors, and beamed from an antenna to a thruster. Conversion of the microwave energy into thrust was performed using a thermal thruster with a highly efficient microwave-absorbing heat exchanger.