[amsat-bb] Magnetic Sail

Mike Lemons motie at mindspring.com
Sat Dec 29 14:56:45 PST 2007

I was trying to think of an inexpensive way to get from LEO to HEO when 
I came up with the idea of  using electricity to move the satellite like 
an electric motor.  The satellite is moving through the Earth's magnetic 
field, so if you put a big coil on it, you should be able to time the 
current through the coil in order to get the satellite to move in 
whatever direction that you want.

Then, I found that some one had already thought of it: 

Quoting: "By varying the magnetic sail's field strength over the course 
of its orbit, a magnetic sail can give itself a "perigee kick" raising 
the altitude of its orbit's apogee."

In the simplest mode, you would energize the field to repel from the 
earth's pole as you pass over it.  In this form of magnetic levitation, 
the satellite is going to want to flip over.  You could compensate for 
this by having two coils extended on moment arms in a shallow "V" 
angle.  See http://en.wikipedia.org/wiki/Dihedral  This would prevent 
roll.  You would need two more "wings" at a 90 degree angle to control 
for yaw.  You might be able to get away with only three wings 120 
degrees apart.

I don't know how long it would take to get to HEO.  That would depend on 
how strong of a field you could produce over how big of an area.  It 
would work better with a lighter craft.

This method of propulsion has the potential for reducing the cost of 
getting commercial satellites into higher orbits.  Another advantage is 
that you can reverse the process to de-orbit your satellite at end of 
life.  This method of propulsion might work to take you to another 
planet, too.

It seems to me that NASA would be interested in seeing if this works.  I 
for one wish that NASA would do more proof of concept experiments like 
this with alternate methods of spacecraft propulsion.

More information about the AMSAT-BB mailing list