[amsat-bb] Re: Could we raise orbit thru magnetorque?

[G0MRF@aol.com]

Hi all.
 
I think we have all had fun looking at ways to raise an orbit and the  answer 
seems to be, from the basic physics, that you will exert an extremely  small 
force the effectiveness of which is dependant on the distance between the  
poles and the strength of the magnet, and some other things too
 
However, to put this into perspective...........AO-51, which we all know  and 
love, uses a similar principle for attitude stabilisation.  Instead of  
repelling the space craft into outer space the magnet on board causes the  
spacecraft to rotate one turn per orbit. This ensures that over the northen  'pole' 
the antenna end of the spacecraft points straight down. Over the southern  pole 
the antennas point in the other direction. (sorry southern  hemisphere)
- for those of us living between 50N and 50S it also allows us to predict  
whether we will get better signals (particually on 2.4G) as the spacecraft  
approaches or moves away from us. By knowing the attitude we know if the  antennas 
are pointing towards us or not.
 
Of course, what does not happen with AO-51 is that force of attraction from  
its magnet does not cause any measurable deteroration in the orbit. i.e. AO-51 
 does not show any tendancy to dramtically spiral down and crash into the  
earth.
 
why? well imagine the forces involved.  
1) you have the kinetic energy of a 20kg (?) spacecraft travelling at  
18,000MPH.  That's a lot of energy. - difficult to imagine....OK Just  imagine 20kg 
hitting the side of your house at that speed....Yes, thats a lot of  energy!
 
compared to.
 
2) The force of a magnet with the poles 1 foot apart  1.5 million feet  from 
the ground.
 
Not sure if that helps. But it did make me understand how something with so  
much energy due to its velocity can be easily rotated on its own axis by a  
magnet, but not have its direction of motion changed by a that magnet.
 
tnx
 
David  G0MRF
 
 
 
 
 
 
In a message dated 22/02/2007 07:32:52 GMT Standard Time, ojwanga2 at asme.org  
writes:

The  craft could push-off the magnetic field of the planet, using it as a  
rail.

Andrew.
KI4LTH/5Z4FT.