ivy@ihuxt.UUCP (08/07/84)
Loss of orbital energy (altitude) to stratospheric friction is a real problem. Using an orbiting tether as a generator winding, sweeping through a planet's magnetic field, and using that to replace the orbital energy lost to friction is an excellent idea. Now, having solved the problem of energy lost to friction, how shall we replace the orbital energy lost (converted) to electricity? How about a bicycle with a generator on the front wheel, and an electric motor on the back? Wiring them into each other won't make up for wind resistance... without adding a step-up transformer in between! ;-) D Iverson
eder@ssc-vax.UUCP (Dani Eder) (08/08/84)
[7 August 1984]
The way you make up frictional drag losses in LEO with a conductive
tether is to use a solar array to force current up the tether. By reversing
the 'generator effect', you now have a motor. The system now gains
orbital energy at the expense of electricity.
Force on a current-carrying wire in a magnetic field is
IL x B
where I=current in Amperes, L=length of wire(meters),x= cross product (math
function that tells which way force is directed), and B is magnetic field in
Teslas. In order to have a one way current, you have to collect electrons
at one end (a large sheet of aluminum), and get rid of them at the other
(an electron gun). Losses in the system are parasitic power to run the
electron gun (10-20%), and I*I*R resistance losses in the wire.
Although this propulsion system only works well in the ionosphere,
it gets lots better thrust per watt than ion propulsion, and consumes
no fuel to boot. It can also be scaled arbitrarily small, i.e.
1 Ampere, 100 meter wire, television type electron gun, = 1/300 newton.
Dani Eder / Boeing Aerospace Company / ssc-vax!ederandrew@parallel.UUCP (Andrew Knutsen) (08/10/84)
If there was energy lost due to stratospheric friction, Id be more concerned with atmosperic heating than slowing down the day. I dont think it would take more than a few seconds of increased revolutional period to boil us all to vapor... What a pleasant thought eh? Such are the pitfalls of large scale projects. Andrew
ix241@sdccs6.UUCP (08/13/84)
David Brin has used this idea in a short story that appeared in Analog magazine in Oct or Nov 1983. The idea has also been discussed at the California Space Institute over the last couple of years. John Testa UCSD Chem sdccs6!ix241