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Re: Magnetic Field Stabalization




Hi Bob,

A little late in responding here but check out:

http://ssdl.stanford.edu/opal/WeeklyUpdate20000211PM.html

Opal is a free flyer with no stabilization mechanisms onboard.  Opal just
tumbles.  The URL above shows (check out the temp graph) that Opal indeed
stopped spinning for about a day and got awefully hot.  The batteries
reached 70+C (they're specified max temp is 30C).

We're not exactly sure what caused that event and we haven't seen it
again.

Also, when Opal was first launched we spun at several RPM.  It is spinning
much slower now and it affects our communications.  There are nulls in the
antenna pattern and we now see them longer because of decreased spin
rate.  Sometimes they last several minutes and can render a pass
useless.  We wish we had something on their just to spin it up abit but so
far having nothing has worked.  And the cost was right!

Hope that helps.

--Jamie
jwc@stanford.edu



On Wed, 26 Jul 2000, Bob Bruninga wrote:

> Satellite Designers,
> 
> I had wanted to add bar magnets to our satellite (a cube) to give us a
> predictable oreintation.   The alternative is nothing and just letting it
> be random.  I dont like this. since I fear it could stay in one
> orientation for long periods and overheat on one side.
> 
> The proponent of this laisse faire approach says that if you wanted to
> keep it oriented one way, you couldnt, so he concludes that it will
> therefore always be moving.   But he cannot tell me how much.
> 
> Where is the best report on the spin/tumble of the microsats and even
> better, how can I prove to this person that there is a risk of temporary
> stabilities that can overheat one side.  Or are my fears unfounded and
> random forces will assure even heating of a 10 inch symetric cube with
> only a few asymetric tape measure whips?
> 
> de WB4APR, Bob
> 
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