[amsat-bb] Nuclear Powered Birds

["Al copland" <allan_gm1sxx@xxxxxxxxxxx>]

Hi,

There seems to be some sort of idea doing the rounds on the BB that apart 
from COSMOS-954, RTG's were only used in missions to other solar system 
bodies.   This is not the case.

Cosmos-954 was only one of 16 Radar Occean Reconnaissance SATS launched into 
LEO by the former Soviet Union.

The RTG's of these birds used liquid sodium coolant which had a tendency to 
leak out into space as minute droplets.  This is actually quite well 
documented by various sources and is a major source of irritation to gamma 
ray astronomers.

After the 954 accident, the spacecraft design was altered to enable the 
reactor core to be lofted into a higher 'parking orbit' with the intention 
that the radioactivity would decay naturally as the core aged, hopefully 
before it re-entered earth's atmosphere.

You will be reassured to know that the system appears to have worked 
properly in the post Cosmos-954 launches.

The modified RTG was also designed  with the intention that the radioactive 
material would be dispersed widely in the event that the motor used to loft 
the core did not work properly.  The core would be ejected anyway, and would 
disperse the radioactive contents far more widely than the unintentional 
decay of Cosmos-954 did.
That way, the debris from a failed boost would not come down on a single 
narrow 'footprint' but be dispersed very widely as the core disintegrated 
during re-entry.  In a worst case scenario, this does make some sort of 
sense.

The following URL makes quite a good starting point for those with an 
interest in this matter.

http://apollo.cnuce.cnr.it/~rossi/publications/iaf97/node2.html#SECTION00020000000000000000

There is also a very good book covering the decay and clean-up operation in 
the aftermath of the 954 accident. Unfortunately, I cannot remember the 
authour's name... I donated the book some time ago to our local observatory. 
The Book is called 'Operation Morning Light' and is recommended reading 
material for those with an interest in the Cosmos-954 incident.

Regards,
Allan Copland
GM1SXX

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