Satgen93   Salyut 7 and NASA Keplerian Elements - Use with Care    7Jan91

Several enquiries asking about Cosmos 1686 ,the Space Tug attached to the
Salyut 7 space station for the last 4 years , have questioned whether it
is still attached. Answer - I do not know.

Since Salyut's engine failed in 1984, the Russians have used several other
vehicles to push the station up when it dragged down to a dangerously low
altitude. Cosmos 1686 has been doing the job for over 4 years and it was
probably still attached to Salyut , when the station went out of control
in 1990. At which point it became clear that Soviet controllers could no
longer use 1686 to control Salyut.

Salyut and 1686 have clearly been hard docked together for a long time,
but NASA elements have always shown them to be on slightly different
orbits. This is because they launched separately and NASA have continued
to calculate their individual orbits separately , rather than
rationalising them to the same figures once they docked. You can see the
application of this rather odd approach if you look at the Keplerian
elements for Mir, Kvant I, Kvant II, and Kristall , 4 large lumps all hard
docked together , each of which gets different NASA Keps.

So please be aware that NASA publication of different Keps for Salyut 7
and, 1686 , does not mean they have separated. NASA always warn that their
Keps must not be used for serious work. This is clearly a situation where
that comment applies, so we cannot use the Keps to tell whether the two
units have in fact been separated.

Trying to use a different approach to this question , I had dug out all my
photos of Mir and Salyut passes over Scotland looking for something useful
to describe visual tracking in the forth coming Mir handbook. I found I
had photos of Salyut both before and after the arrival of 1686. When the
two are together Salyut + 1686 has a sunlight reflection trail slightly
brighter than a 1.52 magnitude star. When alone Salyut was much less
bright being about magnitude 2.5 So for the last month I have tried
looking on suitable orbits. Unfortunately none of these orbits have been
blessed with clear skies. So unless we get suitable orbits and clear skies
before Salyut re enters, the question will remain unanswered.

UA3CR indicates some doubt now as to the chance of RM-1 launching on 7th
Jan . None the less it should go soon.

I hope U of Surrey are successful in improving the through put of
broadcast bulletins on the Uosat3 and other Pacsats. The present situation
is rather dissappointing, as is the news that Dove is unlikely to get
Digital voice before spring 91 and the AREM experiment in Mir is likely to
slip several months and will certainly not now start in February.

Please note that if you want to send me any packet queries my home BBs is
now GB7SAN following a reorganisation of the Central Scotland network
consequent on a need to reduce mutual QRM. 73 de GM4IHJ @ GB7SAN