99- 12 E = 25653 strange flashes

Kurt Jonckheere (kurtjonckheere@hotmail.com)
Thu, 13 May 1999 00:53:00 PDT

Subject: 99- 12 E = 25653

hello all,

last weekend, Tristan showed me some recent pictures he made.

One of the pictures was very surprising to me, it showed a tumbling
satellite (99- 12 E  =3D 25653 =3D A2 Soyuz Ikar third stage) with quite
a few short specular flashes during one tumbling period !!

You can find the pictures on my home page :

http:// bewoner.dma.be/kjon

Does anybody has some more info about these type of rocket ?


The photograph (+ detail) was made by Tristan Cools on
April 17, 1999 at 20h18m UT, from Rijckevelde, Belgium with a
Canon AE1, 135 mm F2.8 objective.  The rocket was at 630 km height,
flashing regularly to magnitude +2 with a 1.8 seconds period.
[measured by Leo Barhorst, Michel Jacquesson and Tristan Cools between
April 16 and 18]

Taking a look at the original photograph (and negative) and also on
these pictures (if your browser is set to high enough resolution) you
can clearly see the short sharp (specular?) flashes during some part
of the pass.

There are about 16 short flashes during one tumbling period, giving
a time of about 0.1 seconds between the sharp flashes, duration of the
flashes about 0.01 to 0.02 seconds, which might give a clue to the fact
that nobody has seen them visually till now.

Are these specular flashes caused by some additional stuff (engine
outlets ?) on one end of the stage ?
Why are they visible so long (during more than half of a tumble
of the rocket), is the rocket spinning and tumbling together ?
I can imagine having some short bright specular flashes during
one pass if the geometry is correct, but my imagination
isn't big enough to explain this...

hope somebody can solve this mistery,

Kurt Jonckheere and Tristan Cools

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