Greg
Popular Science, July 1998
( US $2.99, Canada $3.99 )
Flying on a Beam
[this article will eventually show
up on http://www.popsci.com/ after the next issue comes out.]
Tests performed at teh White Sands Missile Range
in New Mexico have demonstrated the feasibility of "lightcraft",
vehicles powered by laser beams from sources stationed on the ground or
in orbit. The rear section of a lightcraft forms an elongated, parabolic
mirror that focuses laser beams onto the craft's rim. There the
concentrated energy produces a flash of hot, blue-white plasma that
propels the craft forward.
Leik Myrabo of the Rensselaer Polytechnic Institute and Franklin Mead of
the Propulsion Directorate of the United States Air Force Research
Laboratory claim that within five years a lightcraft weighing 1 kilogram
could be launched into orbit for $250 worth of electricity. By using
its mirror as either a transmitter or telescope, a lightcraft could be
adapted for a variety of telecommunications or remote sensing
applications.
In a series of experiments conducted over the pas year at the High
Energy Laser Systems Test Faacility at White Sands, a 10-kilowatt pulsed
infrared carbon-dioxide laser has launched small lightcraft weighing 30
to 40 grams as high as 23 meters into the air. In tests planned for
later this year, Myabo and Mead hope to reach an altitude of 600 meters.
To reach even higher altitudes, the researchers would need a more
powerful laser. Such and instrument exists, but lies in mothballs at
the test facility. Known ad Driver, it is a 100-kilowatt laser that
packs enough wallop to boost a lightcraft to an[sic] height of at
least 100 kilometers [if it doesn't melt the thing!]. However
rebuilding it and modifying it for experiments with lightcraft would
cost roughtly $500,000.
If Myrabo and Mead can secure the funds necessary to rebuild and test
Driver, people could one day fly on highways o flight beamed from
solar-powered transmitters in space. Lightcraft offer environmental
benefits as well as cost savings, says Myrabo. A lightcraft emits
nothing more than hot air, and its energy comes from above the
atmosphere. -- Will Cooper