Trips into space could become much more affordable and popular, bringing in a new era of space tourism, two US scientists say.

According to their calculations, reported in the magazine New Scientist, blasting into orbit could eventually cost as little as $15,000 - a fraction of the current price.

The ISS has hosted only two space tourists so far

So far only two men have paid to go into space.

The trips cost Dennis Tito and Mark Shuttleworth $20m each for just a few days aboard the International Space Station (ISS).

But Jay Penn and Charles Lindley, from the Aerospace Corporation in California believe a ticket into orbit could come substantially down in price.

They say that by using a two-part craft, space travel would become much cheaper.

Pioneering design

A reusable rocket would carry a smaller winged capsule to the edge of the atmosphere, then glide back to Earth for refuelling, while the capsule would carry on towards an orbiting space station.

Here passengers would disembark and others would board for the return journey.

Russia sells ISS tickets because it is short of space funds

Using this method, the scientists estimate the craft would make 9,500 flights a year compared with just 10 by the shuttle.

At $15,000 per passenger the venture would become profitable within six years of launching.

The new craft would be much cheaper to run, as they would only require a few dozen engineers and not the thousands needed to maintain the shuttle, which is often pushed beyond its design limits.

They also suggest that changing the fuel source from liquid hydrogen to paraffin would reduce costs significantly.

The new system, the scientists estimate, would take at least seven years to develop.