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The Question
(Submitted September 27, 1998)
I was rather interested in the new type of propulsion mentioned on
television. Please e-mail me about the subject.
The Answer
Hello!
Thank you for writing to "Ask a High-Energy Astronomer." It is great that you are
interested in astronomy and in space travel; the technology you are
probably referring to is an "ion thruster." From a web page on a
course in Plasma and Electric Thrusters given at the University of
Wisconsin comes this definition of Electrostatic or Ion Thrusters:
This class has a single member, the ion thruster. Its key principle is
that a voltage difference between two conductors sets up an electrostatic
potential difference that can accelerate ions to produce thrust. The ions
must, of course, be neutralized--often by electrons emitted from a hot
filament. The three main stages of an ion-thruster design are ion
production, acceleration, and neutralization.
(http://elvis.neep.wisc.edu/~jfs/neep602.lecture30.plasmaProp.96/neep602.lecture30.plasmaProp.96.html
This page appears to have disappeared.)
An ion thruster is being used by Deep Space 1, which uses solar panels as
a source of energy to build up the necessary electrostatic potential to
accelerate the ions:
http://nmp.jpl.nasa.gov/ds1/tech/sep.html
They are also used for some new commercial communications satellites
(Hughes offers this option) for altitude and station keeping.
Cheers,
J. Allie Hajian
John Cannizzo
for the "Ask a High-Energy Astronomer" Team
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