Re: Orientation of discarded HST array

Tristan Cools (tcools@nic.INbe.net)
Mon, 10 Mar 1997 23:08:01 +0100 (MET)

>>One possible reason for it not doing so is that it has somehow managed
>>to settle into a stable low-drag orientation.

I too wondered why the HST array hasn't decayed yet.  I recall that the
press and other sources told us that the array would decay within one year.
In fact some books have already mentionned that it decayed in the Earth's
atmosphere.  Well, its orbit has been lowered but not that much as one
should expect.

Here are all the photometric period measurements found in PPAS6:

90- 37 C 93-12-24 00:44      RIK               23     mag +7->4(4.5)
90- 37 C 94-02-11 01:26      MM   15   0.5   1 15     3.5-7
90- 37 C 94-02-12 01:31:25   WJW                      flashes to mag 8
90- 37 C 94-02-14 01:39:22   WJW                      peak elevation 20 degrees
90- 37 C 94-02-15 01:43:16   WJW                      problem with stopwatch
90- 37 C 94-03-30 02:47:17   WJW                      visible continuously
90- 37 C 94-05-14 04:20:46   WJW                      twilight, flashes visible
90- 37 C 94-05-16 04:23:14   WJW  71.8 0.1   9  7.98  sm
90- 37 C 94-05-17 04:26:13   WJW  71.8 0.1   9  7.98  sm
90- 37 C 94-08-24 01:54      MM  103.9 0.5   6 17.3   5-7, flash to 2
90- 37 C 94-11-27 02:11:22   WJW  52.0 0.1   6  8.67  sm, shadow
90- 37 C 94-11-28 02:11:25   WJW  69.3 0.1   4 17.3   2 complete array notation
90- 37 C 95-10-27 00:36      MM   51.6 0.5   3 17.2   flash to 3

General conclusion would be that the solar array is still tumbling with a
period of about 17 seconds.  Its period didn't change much from 94-02-11
untill the last observation so I do not believe it has settled into a stable
position. 

Still it should be nice to have some new observations of it, at least to
know for sure.


Greetings,
Tristan Cools
tcools@nic.INbe.net
BWGS member(Belgian Working Group Satellites)

Damse Vaart:    3.2478E/51.2277N 3.75m
Rijckevelde:    3.2856E/51.2045N 6.25m
Brugge     :    3.2166E/51.2104N 5m