-
An artists rendering of a Light Sail solar powered sail - Source: Reuters
Backers of a failed mission to launch the world's first
solar-sail spacecraft unveiled plans to try again five years later
with a smaller, swifter satellite to test the limits of sunlight
propulsion.
The privately funded venture, organized by the Pasadena,
California-based Planetary Society, is based on the premise of
spaceflight powered not by rocket fuel or chemical propellants but
by streams of photons - light particles - pushing against a sail in
the vacuum of space.
Some space enthusiasts see solar sailing as a first step in
light-powered propulsion technology that may prove the most
feasible mode of travel to distant stars.
But experts say the technology has nearer-term applications in
establishing permanent solar weather stations for monitoring
magnetic storms on the sun that can wreak havoc on Earth-bound
communication networks and electrical grids.
The project grew out of an idea imagined by the society's
co-founders - executive director Louis Friedman and late astronomer
and author Carl Sagan - to send a solar sail craft to rendezvous
with Halley's Comet in the 1970s.
The first attempt to launch such a space vehicle, dubbed Cosmos 1,
ended in disaster when a Russian rocket that was supposed to carry
it into orbit malfunctioned shortly after lift-off from a submarine
in the Barents Sea in June 2005.
Organizers have since redesigned the spacecraft.
The new LightSail vehicle, the size of a loaf of bread, is
smaller and 20 times more lightweight than Cosmos but built to
accelerate more quickly once its aluminum Mylar sail is unfurled in
high orbit, 800 km or more above Earth.
That's about twice as high as the usual orbit of NASA's space
shuttle, said the Planetary Society's Bruce Betts.
The sail consists of four triangular blades that combine into one
large square about five metres wide and five microns thick -
one-quarter the thickness of a plastic trash bag.
No launch date has been set. But backers plan to have the
LightSail-1 ready to go as early as the end of 2010.
They are looking at various US or Russian launch options, Betts
said.
Once LightSail reaches its initial orbit, mission controllers will
test its novel propulsion system by trying to use the force of
sunlight exerted against the craft's sail to push the satellite
higher above Earth, Betts said.
Subsequent missions of LightSail-2 and LightSail-3 will seek to
demonstrate longer-duration flights to even higher orbits, and
ultimately to a point beyond Earth orbit that affords better
observation of the sun.
Ultimately, for voyages deep into space away from the sun, the
spacecraft would need additional propulsion supplied by a laser
beam directed at its sail from Earth to supplement fading sunlight
reaching the vehicle, Betts said.
