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 |  | Rocket Engines of the Future
By Ray Villard
Special to space.com
posted: 06:56 am ET
28 September 1999
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NASA
engineers are developing a radically new type or rocket engine that
harnesses the power of stars to cut travel time to Mars, for example,
from the current nine months down to three months. Called the
gas-dynamic mirror engine, it traps and heats gas to temperatures as
sizzling hot as those found at the core of the sun. That's hot enough
to allow for nuclear fusion by combining lighter atomic nuclei into
heavier nuclei.
Within
a few months, a six-foot long model of the engine will be fired-up by
injecting a superheated gas confined between powerful magnets at either
end of the engine. Within a couple of years, the engineers hope to
achieve a sustained nuclear fusion reaction in the hot plasma.
Attempts
to build fusion reactors on earth for generating electricity have been
bedeviled by the fact that some of the plasma always leaks out. But
this becomes an advantage for fusion-powered rocket engines. The plasma
that leaks out produces a thrust that propels the spacecraft. The trick
is to sustain a fusion reaction while tapping a little of the gas for
thrust.
A
second engine under development uses a different method to achieve
fusion. Powerful laser beams zap BB-sized fuel pellets to create hot
plasma contained in a metal shell.
The
fuel pellets would be zapped by antimatter inside an even more advanced
engine imagined. This would eliminate the need for a bulky laser
apparatus the spacecraft would otherwise need to carry. Antiprotons,
which contain the opposite electrical charge of normal protons, can be
manufactured today in particle accelerators and stored as fuel inside
powerful magnetic fields.
Such
engines could catapult a robotic probe to the nearest star to our sun,
Alpha Centauri, with a travel time of only 200 years. Though that
sounds long, it is a quick hop relative to the 168,000-year journey it
would take for a conventional chemical-rocket engine.
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