Re: Decay Forecast
Alan Pickup (alan@wingar.demon.co.uk)
Sat, 20 Feb 1999 18:21:15 +0000
Harro.Zimmer <Harro.Zimmer@t-online.de> writes
>Another candidate for the next days may be MOLNIYA 3-28 (1986-031A). At this
>time
>I can't predict a realistic decay data. The last released ELSET epoch was
>99041.536... In respect to the high solar activity at the last days I speculate
>he may come down not later then Feb 28.
>Alan: What's your opinion?
As you say, Harro, the last elset was:
Molniya 3-28 20484 x 100 km
1 16683U 86031A 99041.53659448 .07863936 00000-0 18459-2 0 5255
2 16683 61.4479 159.3921 6113565 260.3964 29.9480 4.03400129 94103
However, I believe that the perigee height (100 km) is wrong - it is
higher than given by all but one of its other elsets this year, during a
period when luni-solar effects were pushing the perigee lower. A more
realistic perigee height for that time might be 80-85 km and it is
probably 2-3 km lower now. My guess is that the mean motion is now
around 6 revs/day with ndot2, the drag term, about 0.12.
I do not think that the increased solar activity will have much impact
on the lifetime. In such an orbit, almost all the drag is felt at
perigee and, below about 125 km, there is little variation in
atmospheric density with solar activity.
It is still a hard decay to call, but I'm inclined to put "March 5?" in
my next SatEvo decay list, due tomorrow. Things will be much clearer
when it is recovered by SpaceCom, I expect within the next few days.
Alan
--
Alan Pickup | COSPAR 2707: 55d53m48.7s N 3d11m51.2s W 156m asl
Edinburgh | Home: alan@wingar.demon.co.uk +44 (0)131 477 9144
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