Satgen 110   STS 39's Odd UHF , Mir Visuals   by GM4IHJ 6th May 91

There have been 5 or 6 Shuttle flights in range of Scotland in recent
years but as far as I am aware, none of them made a bleep on UHF. So this
last weeks flight STS 39 with its sporadic UHF cover was both interesting
and unusual. Firstly there was no pattern to the signal timing. Some
complete orbits were silent , others were not. Second , when signals did
occur they were too short to be classed as communications. One short " Is
that OK Fred ",in an 8 minute pass is not communications. When heard
Shuttle signals were S9 plus, and they were clearly coming from Discovery
and going to either Ground Control or someone in the Shuttle cargo bay (
although the latter is unlikely as no one called Fred was in the crew).
So what was actually going on ?? My guess is that UHF was being put on the
air , now and again, by mistake. If anyone else has a clearer picture of
what was going on I would like to hear from them. Unfortunately the NASA
14.925 rebroadcast channel was not much use. It could be heard but heavy
QRM from Continental Europeans made it unreadable most of the time. So it
provided no clues to the odd behaviour on UHF.

Have temporarily lost RS12 , but RS 10 is providing both beacon and
transponder signals. Unfortunately however RS 10 is not well placed in
respect of the Right Ascension of its ascending node, noting that its
ascending south/north equator crossings are more than an hour west of the
suset grey line that produces good long range sub horizon DX. Unlike the
Salyut Cosmos signals which quickly changed RAAN every 60 days or so, we
get no such change from RS 10 or RS 12. Both take many months to
substantially alter RAAN. So while some good DX exists as shown by South
African 28MHz terrestrial beacons, this is not helping RS10 users.

The Mir Space Station should start giving some good visual tracking passes
this week and next, noting that at this time of year the midnight Sun is
not far below the UK northern horizon at midnight. Mir up at 380kms sees
the midnight Sun over the other side of the north pole when the Sun is
near Hawaii in the North Pacific. So Mir coming north towards UK over
Spain or Southern France gets up to about the latitude of Paris and
suddenly sees the Sun over the pole.  Please note that this means that on
most clear sky visual passes of Mir either side of midnight you do not see
Mir until it is someway above the UK horizon . Then as it suddenly sees
the Sun over the north pole it reflects the sunlight back to observers on
the ground appearing as bright as the Magnitude 1 star Aldebaran and it
stays brightly sunlit until its orbit carries it back down below the
latitude of Paris.
Be aware also that this midnight sun effect allows visual tracking of lots
of other satellites. If you simply look east at about 30 degrees elevation
you should see at least one navigation satellite cross your field of view
going north south, or , south north every 4 minutes or so. Even more
obvious are the monster photo recon sats which pass over UK heading , if
American just west of the Pole, if Russian just east of the Pole. Good
hunting and 73 de John GM4IHJ @ GB7SAN. ( Nice to see you at Kelso, Dave,
John, Derrick and all ,especially those from south of the border).