Riding on microwave
spaceplanes of the future can be put into orbit by firing microwave beams from satellites to help them cut their way through the air. The satellites would generate the microwaves by gathering and converting solar energy.
After eight years of research, engineers at Rensselaer Polytechnic, New York, have successfully tested the new propulsion system in a tunnel that can recreate the shock wave effect caused by focusing microwaves. Shock waves are created by an abrupt change in pressure caused by an object moving faster than sound. They have established that microwave beams can be focused to blast away the air in front of the craft like an invisible nose cone.
It may also be possible to use microwave beams to drive a fan-jet engine, propelling the ship forward. This means future crafts would no longer need to carry heavy tanks of rocket fuel.Scientists have realised that spacecrafts which carry their own fuel are too heavy and expensive and may never offer an affordable option for routine access to space.
Leik Myrabo, associate professor at Rensselaer's mechanical engineering department, says that a vehicle can travel in the slipstream (current of air driven back by a moving object) of the shock wave at speeds of up to 19,000 miles per hour, 25 times the speed of sound. Myrabo says, "We are a step closer to proving that affordable, hypersonic aviation and space travel by individuals for business or pleasure could become a reality."
The test was successful at 10 times the speed of sound. This is less than the speed needed to take a spacecraft into orbit but fast enough to show that the concept works. The futuristic craft, shaped like a lens, would weigh less than a small car 544.8 kg but, being about 30 ft in diameter, it would cover one side of a tennis court.
Such a craft could fly people from the uk to Australia in 45 minutes or take visitors to the moon in less than six hours. Myrabo believes that this technology will be ready for the next generation of travelers.