ARISsAT-1

[Bob Bruninga]

> (about the fading) saying that no stabilization was
> designed in to the satellite, so that it would
> freely tumble, and cause even distribution of
> heating/cooling. I can't believe that was a
> deliberate design feature...

Yep, I imagine it was.  That is what we did on PCSAT and with a rotation of about 1 RPM  and the resulting temps inside were about room temperature with only a 2 degree or so variation with the rotation.

Imagine my shock when we did the solar analysis on our next PSAT which is designed to point one side at the sun.  The temps on that side get to 95C (that's over 200F) and the temps on the non-sun side get to -60, that is nearly as cold as dry ice.

So, yes a spin is required unless one goes to other extrordinary schemes to transfer heat.  Of course the 9 RPM is quite high and does interfere with communications, but as noted before, it will slow down and will get to where it rotates only about the antenna axis giving very little RPM fading.

1RPM would have been fine.  Maybe the cosmonaut did not calibrate his throw?

Bob, Wb4APR