globalbriefs
Starlight Traveler
Dreams of Sailing
Through Space
The National Aeronautics and Space
Administration has announced that
the Planetary Society, founded by
scientist and author Carl Sagan, is
set to build and fly a series of solar-
sail spacecraft, dubbed LightSails,
first in orbit around Earth and then
into deeper space, in the next three
years. The beauty of LightSails is
that they are powered by sunshine,
which carries both energy and
momentum; unlike rocket fuel, this
gentle force fires continuously.
Over time, a big enough sail,
perhaps a mile on each side, could
reach speeds of hundreds of thou-
sands of miles an hour, fast enough
to traverse the solar system in five
years. Riding the beam from a pow-
erful laser, a sail could even make
the journey to another star system in
100 years, a human lifespan.
Dr. Louis Friedman, director of
the Planetary Society, a worldwide
organization of space enthusiasts,
says eventual passengers will likely
be robots or human genomes en-
coded on a chip, due to the need
to keep the craft light, like a giant
cosmic kite. In principle, it could
tack like a sailboat. Japan is already
testing solar sails deployed from
satellites or rockets, although none
are traveling anywhere yet.
These are visions for the long
haul, advises Freeman Dyson of
the Institute for Advanced Study in
Princeton, New Jersey. He remarks:
“Think centuries or millennia, not
decades.”
natural awakenings February 2010
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