A do-it-yourself spaceship which can be built in the back garden could be on the market within three years.

The Kitten is a rocket assembled from a kit that will soar its pilot and two passengers to a height of 200 kilometres at four times the speed of sound.

After making the hop into space - defined as 100 kilometres up - the 20ft craft will glide back to Earth, like Nasa's space shuttle.

At a projected price of only £312,000, it would be affordable to a large number of enterprising space enthusiasts.

The Kitten is being developed by the Cerulean Freight Forwarding Company, of Washington, US, which was established to promote space freight and tourism.

Its president, James Hill, said: "It should be as reliable as any other kit - a boat, a helicopter or a small private sub."

Amateurs already build and fly kits for all kinds of aircraft, including helicopters and jet planes.

The Kitten will be built from off-the-shelf components that already have safety approval from the US Federal Aviation Authority, New Scientist magazine reports.

The spacecraft, which has delta wings, a large tail fin, and a big glass cockpit window, is powered by a mixture of methane and oxygen. It takes off and lands on a traditional runway, and flies like a plane to a height of 40,000 feet.

At this point the craft accelerates rapidly into space.

After coasting for two minutes, the nose pitches down and the craft begins its descent. The whole round trip takes about two hours and includes four-and-a-half minutes of weightlessness