Re: USA 40 debris storm

jvarney@quiknet.com
Mon, 5 Feb 1996 01:22:41 -0500

At 08:41 AM 2/4/96 -0800, Allen Thomson wrote:

>    I noticed that the November Satellite Situation Report from 
>NASA shows a debris storm associated with USA 40.   The NORAD 
>catalogue numbers associated with the E through J objects appear 
>to have been assigned in late 1992, K in mid 1993, L through W 
>in mid 1994, and the remainder in late 1994.  Does anyone know 
>if this fagmentation history is similar to any past events, or 
>have any suggestions as to its significance? 

For the last couple of months I've been (slowly) working on digitizing
a document called "History of On-Orbit Fragmentations."  I still
have got a ways to go before it's completed.  When finished, I'll mention
it's availability on SeeSat.

The copy I have does not mention USA 40.  It has data up to April 1992;
from your description it appears the USA 40 event occured after the document's completion.  The document lists USA 19 and USA 68 as having fragmented.

The authors did quite a bit of analysis of archived raw NORAD data.  They
had to do this because NORAD has historically been slow and erratic at
cataloging debris.  Although the cataloging sequence suggests three frag-
mentation events since 1992, I wouldn't rely on cataloging alone as an
indicator of what happened to USA 40.  There could have been only one event
and the cataloging has been slow to catch up.

If I had to draw a conclusion based on the cataloging pattern, I would say it's consistent with other explosive fragmentations.  The number of debris is 
far too high to be explained by operational debris or decomposition due to environmental wear.  Conversely, the quantity of debris for USA 40 is lower 
than that exhibited by one satellite thought to have suffered an on-orbit 
collision, Cosmos 1275.

The mechanisms by which payloads can fragment explosively are: explosive charge
detonation (intended or not), attitude control system failure, battery failure, 
range safety device.

 -- Jim

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Jim Varney          |  121^ 23' 54" W,  38^ 27' 28" N   |     Sacramento, CA
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