On 8/3/11 8:39 PM, g0mrf@aol.com wrote:
Apx. 6 second spin period puts deep nulls in transmitted signal. - Not sure if this is due to linear polarisation of my receive antenna or blockage from spacecraft.
Since we don't have video of the actual deployment we don't know how it was turning at release.
But remember the physics of this. Any body that isn't absolutely rigid will eventually settle down to a stable spin about the axis with the greatest moment of inertia. That configuration minimizes kinetic energy while still conserving angular momentum.
Although ARISSat-1 doesn't have any nutation dampers that I'm aware of, the slightest flexing of the structure, the antenna (singular), even tiny movements of the cables inside, will dissipate energy and convert any complex tumbling motion into a smooth spin about the preferred axis. That axis includes the antenna, so it shouldn't fade due to spinning.
So it may simply take some time to settle down into a stable spin without frequent deep fading.
Phil