(meteorobs) Administrative decay of Cosmos 2495

[Matson, Rob D.]

Hi Marco,

Agree with everything you've posted, with the exception of one minor correction:

"This reentry happened some 5 minutes after the satellite passed its descending node at 4:27 UT"

I'm sure you meant its ascending node.

Personally, I find it suspicious (if not a little amusing) that the reentry track occurred so close to
Colorado Springs. If this wasn't a failed administrative decay deorbit burn, given the current
somewhat testy geopolitical situation, one wonders if the decay location was completely
accidental. ;-)  --Rob

-----Original Message-----
From: meteorobs-bounces at meteorobs.org [mailto:meteorobs-bounces at meteorobs.org] On Behalf Of Marco Langbroek
Sent: Tuesday, September 09, 2014 7:32 AM
To: Meteor science and meteor observing
Subject: Re: (meteorobs) Sat re-entry - New Mexico - of possible interest to meteor observers

dfischer at astro.uni-bonn.de schreef op 9-9-2014 14:58:
>> I think I captured a satellite re-entry on the evening of September 
>> 02, 2014, from 2231 MDT to 2233 MDT.  COSMOS 2495 -  as it passed 
>> over New Mexico just before it turned into a fireball over Colorado.
>
> More on the - unusual - context of this observation in this detailled
> write-up: http://www.spaceflight101.com/kosmos-2495-re-entry.html


This part is simply wrong:


"While the ground track is in good agreement with reported observations, the timing of the event shows a significant discrepancy. Propagating the orbit of Kosmos 2945 puts the satellite over the decay location at approximately 4:50 UTC instead of 4:31-4:33 UTC. This 17-minute difference can only be explained by a propulsive event causing the satellite to reduce its orbital period several hours before decay. With a lower orbital period, the satellite would arrive several minutes earlier at a given location"

In fact, the timing of the observations matches Kosmos 2945 much better and I have no idea where they got that 4:50 from (it is wrong). On the last available, pre-reentry orbit it would become visible over the US at about 4:32 UT. As it likely already was lower at the time of observation, it would have been slightly earlier.

Their 4:50 UT is for the pass a day earlier - so a date mistake, they used 2 Sep instead of 3 Sep. Probably confusing the UT date with the local date (3 Sep 4:32 UT is 2 Sep locally).

The relatively minor discrepancy between observed pass during reentry and predicted pass based on pre- re-entry elements, suggest that the satellite orbit was lowered rather suddenly very shortly before the pass over the US started.

This reentry happened some 5 minutes after the satellite passed its descending node at 4:27 UT. So I wonder whether for example an intended orbital plane change (which you normally do by firing a booster in one of the nodes) went wrong and it was sent plummeting down instead. I hardly can't believe the Russians wanted this one to come down over the USA.

- Marco

-----
Dr Marco Langbroek  -  SatTrackCam Leiden, the Netherlands.
e-mail: sattrackcam at langbroek.org

Station (b)log: http://sattrackcam.blogspot.com
Twitter: @Marco_Langbroek
-----
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