/ 4 August 2003

Unique sails pitch bids to cut space flight costs

A huge sheet of mirror-plated fabric on show in New York for the next two weeks could herald a new adventure in space later this year and add new depth to the word ”spaceship”.

Cosmos 1 — to be launched from a Russian nuclear submarine — will be the first sailing ship in space. Its eight silvery blades, each 14 metres long but thinner than a supermarket plastic bag, will unfurl in high orbit and provide lightweight sails which are driven by the pressure of sunlight.

Scientific theory dictates that spacecraft fabric pounded by photons or particles of light from the sun would accelerate very slowly but would go on accelerating under constant bombardment to speeds faster than any existing rocket. A space lobby group called the Planetary Society, a media company called Cosmos Studios and the Babakin space centre near Moscow plan to launch the Cosmos 1 prototype to an altitude of almost 960 kilometres, and test the theory by tilting its sails towards the sun.

Launches into earth-orbit are hugely expensive. The space shuttle’s booster rockets alone burn the energy equivalent of 2-million family cars during each second of launch. The fuel needed to change course or accelerate towards distant planets — or to make possible a return journey — is just so much extra luggage in the boot. So for two decades, researchers have been looking for new, low-cost ways to push spaceships across the vastness of space. One of these is solar sailing, first proposed by dreamers in 1924.

The experimental sail blade, now at New York’s Rockefeller Centre, is part of an exhibition to celebrate the centennial of flight.

Cosmos 1 had its first sub-orbital test launch from the intercontinental ballistic missile tubes of the Russian submarine in the Barents Sea in 2001. Because of a computer problem, the sails were never deployed and the prototype came down in Kamchatka, the Russian peninsula north of Japan.

However, Louis Friedman, head of the Cosmos 1 project and the co-founder of the Planetary Society with the late astronomer-writer Carl Sagan, hopes to see eight silver petal-shaped sails of the 100kg experiment circling the planet by the 100th anniversary of the Wright Brothers first powered flight in a heavier-than-air machine this December.

”During the early 20th century humanity found its wings above the sands of Kitty Hawk. Cosmos 1 represents the next centennial of flight, which will take us and our robotic emissaries from Earth to Mars, Pluto and beyond,” he said.

Ann Druyan, head of Cosmos Studios and widow of Professor Sagan, said: ”Our launch vehicle, a Russian ICBM, has been converted from a weapon of mass destruction into a means of advancing the dream of exploring the universe. In this way, we need to honour the inspiration of Carl Sagan and give our kids a critically needed vision of a hopeful future.”

If all goes well, the 720 square metres of Cosmos 1’s sails will be shifted to collect full sunlight, and then moved edge on to stop acceleration.

In theory, such a spaceship could ”tack” across the heavens at least within the orbit of Jupiter. At greater distances, sunlight would be too weak to make much difference to velocity.

But theorists argue that Earth-based lasers could fire a tight beam of energy to keep the spacecraft accelerating beyond the orbit of Pluto to the distant stars. The Cosmos team will test the idea by firing microwave pulses from an Earth-based radar to measure acceleration on the sails. – Guardian Unlimited Â