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.