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AO-40 Low Perigee Question



Hi All,

I asked Viktor, OE1VKW, about the low perigee and if I should be concerned
about it, ... this is his reply to me. 

73 Paul, VP9MU

> Is it OK if I post your reply to the AMSAT-BB?

If people buy the proceedings from Martha, I have no problem !

	73, Viktor

paul.willmott@omsl.bm wrote:
 
> The tracking software indicates with Ken's #8 keps, that perigee will be
> around 550km, ... this is a bit low for my liking. What options do we have
> to increase this? Perhaps more importantly how long do we have before
> atmospheric effects start to drag us down?

Paul,

AO-40 (eccentricity .809 ) spends now only 22% of his time at altitudes 
below 825 km (1.5 height of perigee). The drag would have to circularize
the orbit first, before the drag can be effective over the whole orbit 
and bring the bird down. 

And for the inclination change we want a low perigee, since only 
then the speed at apogee is low enough. It makes not much sense to 
increase perigee now, it would just cost additional propellant.
Later the argument of perigee will be between 360 and 270 degrees,
where at high inclinations the perturbations from the moon and the
sun will automatically increase height of perigee, to 6000 or 8000 km.

Does this make sense ?

I tried to explain this all in a paper in the Toronto proceedings.
May be you find it on your bookshelf !? 

	Vy 73, Viktor, OE1VKW
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