Another observed decay over S Africa

Alan Pickup (alan@wingar.demon.co.uk)
Tue, 10 Nov 1998 23:57:32 +0000

Dr Ray Wolstencroft of the Royal Observatory Edinburgh has returned from a
recent observing trip to S Africa with reports of what I have today
identified as the re-entry of the Molniya 1T rocket, #25486 = 98- 54 B.

This decayed on October 14 when my (then) final SeeSat-L posting on this
object said...

>...
> Moln 1T? Moln r1                                 133 x 120 km
> 1 25486U 98054B   98287.10325464  .54623595  90106-5  28513-3 0   847
> 2 25486  62.8047 253.0740 0010038 151.2770 209.2142 16.54923183  2431
>
> These prove that it survived a bit longer than my final SatEvo
> prediction suggested, though this comes as no surprise. The elset at
> 98287.04 shows it running 6 seconds late against the prediction at
> that time.
>
> I suspect that decay was most likely near the following southbound
> equator crossing at October 14 03:12 UTC near 2 deg E longitude.


Dr Wolstencroft sent his initial report to the Johnson Space Center on
October 16, but they have not been forthcoming with an ID...

> I am an astronomer currently observing at the South African Astronomical
> Observatory in the Karoo desert near the small town of Sutherland. We have
> had reports from local residents of what appears to be the burn up of
> orbital debris. This occurred at 0525 SA Standard Time (I hr ahead of UT)
> on Wednesday October 14 and comprised what was described as an orange or
> red fiery object which broke up into many separate pieces. It was
> travelling about twice the speed of the Joburg/Capetown planes which are
> often seen here at ~35Kft and much slower than meteors, and the debris was
> reported to be travelling roughly parallel to the horizon. The three
> reports appear to tally and the event was apparently quite a shock to
> those who saw it.
>
> Our observing had finished at all 4 telescopes and so none of the
> astronomers here saw anything as we were in bed!


Dr Wolstencroft has provided the following additional information to me
today:

> I have checked the notes I took when I spoke to these people and can add
> the following useful info:
> (1)The lights were seen low in the sky
> (2)The individual with a clear view of the entire sky (John Wolfaard,a
>    farmer from Ceres) saw about "50 separate pieces of red luminous
>    material" which were travelling in the direction from Ceres towards
>    Worcester
> (3)Rudi Blum and his son from Sutherland were driving towards
>    Makiesfontein passing thro a "kloof" which restricted their view to the
>    horizon,when they saw this bright orange light. They stopped their
>    vehicle and saw it break up into several pieces and from their vantage
>    point without a clear view down to the horizon they counted 7 pieces of
>    debris.The angular speed they reckoned to be 2 to 3 times faster than
>    the speed at which the Joburg/Capetown jets fly over but much slower
>    than meteors with which they are very familiar.
> (4)My recollection (but I didnt note it down) is that the "event" was 
>    said to have lasted for "a few" or "several" minutes but this may be
>    unreliable. The above observation of the angular speed seems to suggest
>    that the event was somewhat shorter, perhaps more like 90 sec or less.
> (5)On the timing, Wolfaard reported 0530 and Blum and son 0520: this
>    difference has presumably more to do with watches being a little fast
>    or slow than with the length of the event!   
> (6)There were "numerous" other witnesses in Sutherland.


I had a little difficulty with my analysis at first. Until, that is, I
realised that South Africa is two hours ahead of UTC, rather than one. The
local time was, indeed, one hour ahead of British Summer Time which was in
force at the time.

In fact, the Molniya rocket decay fits perfectly if it occurred only a few
minutes later than the October 14 03:12 UTC time I gave in my earlier
SeeSat-L posting (above).  If it had remained in orbit that bit longer, the
track would have taken it down the western edge of S Africa and over the
Western Cape. The following track is probably accurate to within 5 seconds
and 0.1 deg (table adapted from output of Mike McCants' LATLONG program):

    UTC   Latitude Longitude
  h  m  s   deg S   deg E
  3 19  0    25.8    15.0     SW corner of Namibia
  3 19 15    26.7    15.5
  3 19 30    27.6    16.0
  3 19 45    28.5    16.6
  3 20  0    29.4    17.1
  3 20 15    30.3    17.7
  3 20 30    31.1    18.3
  3 20 45    32.0    18.9
  3 21  0    32.9    19.5     Between Ceres and Sutherland
  3 21 15    33.8    20.1
  3 21 30    34.6    20.7
  3 21 45    35.5    21.4
  3 22  0    36.4    22.0
  3 22 15    37.2    22.7
  3 22 30    38.1    23.4

For comparison, Ceres is at 33.35S/19.30E and Sutherland at 32.40S/20.67E
according to my atlas. It passed between the two (closer to Ceres) at 03:21
UTC (ie 05:21 local time). As viewed from Sutherland. at a range of ~100 km,
and perhaps 40-80 km high if it was re-entering, it would have been in the
lower part of the SW sky moving from right to left.

The rocket had been launched on September 28 and did part of the job of
placing what appears to be a Russian Molniya communications satellite into
orbit. The satellite was announced as Cosmos 2361, but USSPACECOM calls it
Molniya 1-91 and its orbit is indeed what you'd expect for a Molniya - two
revolutions per day in a 69 deg inclination orbit. There is speculation that
the payload failed after launch and that that is why it was given a boring
generic Cosmos number rather than being called a Molniya.

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
 Scotland    | SatEvo page:     http://www.wingar.demon.co.uk/satevo/