Japan to launch solar-powered spacecraft

Visionaries have dreamed of using light as a form of space propulsion at least since Jules Verne broached the idea in an 1865 novel. Japan will seek to make the idea a reality in the coming days with the launch of a “space yacht” powered by a solar sail.

Other nations have tested solar sails in orbit but the Japanese mission – dubbed Ikaros, an acronym for interplanetary kite-craft accelerated by radiation of the sun – is expected to become the first spacecraft fully propelled by sunlight.

The Japan Aerospace Exploration Agency (Jaxa) originally planned to launch Ikaros on Tuesday, but postponed lift off because of poor weather.

When it is fired into orbit on a conventional rocket, the spacecraft will unfurl a 20m-wide super-thin sail that will harness the force of light from the sun to propel the craft towards Venus while generating electricity from embedded solar cells.

While the choice of acronym could be considered inauspicious – Ikaros, or Icarus, was the mythological Greek who plunged to his death after the sun melted his wings made from wax and feathers – Jaxa has high hopes for what it calls its first space yacht.

Spacecraft with sails, one of which is featured in Avatar, James Cameron’s blockbuster film, have for decades been seen as the most likely way of realising the hopes expressed in Verne’s From the Earth to the Moon that light could be the “mechanical agent” of rapid flight through the void.

A solar sail works by capturing the gentle but constant force exerted by photons from the sun bouncing off its surface. While acceleration is slow, it is not restricted to the amount of fuel a spacecraft carries and could eventually result in much higher speeds than would be possible with a chemical rocket.

Such a spacecraft could even travel towards the sun simply by using its sail to slow its orbit, while future versions of the sort imagined by Mr Cameron’s film could be “pushed” out of the solar system at vast speeds with the help of laser beams.

Jaxa hopes that by demonstrating a sail can also be used to generate electricity using solar panels, the Ikaros mission could pave the way for a solar-powered mission to Jupiter this decade. That spacecraft would use a hybrid propulsion system combining a sail with an electricity-powered ion drive.

A successful flight of the solar yacht, which is piggybacking on a Jaxa mission to send a weather monitoring satellite to orbit Venus, could help to burnish the lustre of a national space programme under heavy budgetary pressure.

In spite of the successful maiden launch of a heavy- lift rocket and unmanned cargo spaceship last year, Jaxa is under scrutiny from the Democratic party-led government. There were calls last year called for funding cuts to the agency’s cargo programme and satellite launches and demands this month for the abolition of its public relations operation in Tokyo.