Cosmos 1 prepares to unfurl her sails in space

When 17th-century astronomers first dreamed of sending a craft into space they imagined a floating structure with sails. Now, some four centuries later, that image may be about to take shape.

When Cosmos 1 is launched at 7.46am on Wednesday NZ time (June 21 Tuesday at 7.46pm GMT), on an intercontinental ballistic missile fired from a Russian submarine, it will herald a new dawn in space travel.

As it reaches orbit, eight triangular sails, each 15 metres long and arranged in a windmill pattern, will unfurl, and the world's first "solar sail" will take place.

Scientists believe the new technology could replace rocket-fuelled missions and carry a spacecraft out of our solar system for the first time.

Solar sails, as the name suggests, harness the power of the sun. Instead of catching the wind, the sails catch photons of light which bounce off them.

Each photon gives the sails a tiny push, which slowly increases in speed, initially up to 100 miles per hour but ultimately it is possible for the craft to reach a speed of 10,000 miles per hour.

The solar sails eliminate the need for fuel and drastically reduce the ship's weight.

The further the sails get from the sun, the less effective they are. But in future it could be possible to propel the sails using laser beams propelled from satellites, or even placed on Earth.

Peter Bond, of the Royal Astronomical Society, said solar sails had several advantages over traditional rockets.

"The potential is quite dramatic," he said.

"Chemical propulsion is very heavy, it can blow up, and there is a problem of pollution. This is much lighter, cheaper and easier to use. In theory, you could send it out of the solar system into another star system."

The world's fastest spacecraft, Voyager 1, would take 70,000 years to reach Alpha Centauri - the closest star after the sun. Scientists hope solar sails could transport a spacecraft to another star within 1000 years.

This is the first time that anyone has tried to put solar sails into orbit.

The Japanese successfully unfurled two solar sails in 2004, but did not send them into orbit.

The Cosmos 1 project is privately funded. It has been organised by the Planetary Society, whose co-founder, the late astronomer Carl Sagan, came up with the idea.

The project's director, Louis Friedman, a former Nasa scientist, said he believed that Nasa and the European Space Agency (ESA) would launch their own solar sail spacecraft "within this decade".

"This is an exciting possibility for future solar system travel," he said.

"It is the only technology we know that leads to interstellar flight. All the major space agencies have programmes, but no flights yet. This will spur them on."

Space exploration has experienced something of a revival over the past few years, as Nasa and the ESA attempt to recreate the fervour that surrounded the first space missions in the 1950s and 1960s.

Much of the focus has been on Mars, where the Nasa robot, Rover, is still exploring the surface of the Red Planet after landing there in 2004.

Britain's effort ended in glorious failure at Christmas 2003 when scientists at the base in Milton Keynes were unable to make contact with their probe, Beagle 2.

President Bush last year said he hoped the US would one day be able to send a manned mission to Mars.

The use of solar sail technology could allow astronomers to set their sights further than the Red Planet, or indeed any planet in this solar system.

Mr Bond said solar sails could lead to a new level in space exploration.

"It could be a historic development. A lot of space agencies have been thinking of it. It just needs somebody to kick-start it. We have been using rockets for 50 years. It is time we started trying something different. This could be one of the ways to do it. I hope it works."

- INDEPENDENT