Satgen78   Shuttle ( and everything else ) experts ?  by GM4IHJ 24Sep 90

The recent confusion caused by silly bulletins about the Space Shuttle
suggest that a word about where and when the Shuttle might be found, might
appropriate at this time.

A typical Shuttle launch from Florida usually goes to an inclination of
about 28.4 degrees with respect to the equator. The Florida launch site is
at latitude 28.4N, so this makes for greatest fuel economy = greatest use
of the earth's eastward spin. By contrast a launch by ESA from Kourou at
5N can go to an inclination of about 5 degrees getting even better fuel
economy.

So most Shuttle flights go to 28.4 degree inclination which gives them an
orbital track which wanders from 28.4N at its most northerly , down to
28.4 S at its most southerly, once per orbit. When on this track the
Shuttle crew can see the horizon much further to the North, with just how
far they can see depending on the Shuttle height. Several recent missions
have chosen 240 kms altitude and it is easy to work out how far they can
see or be seen using the footprint formula :-
cosine of footprint angle= earth radius/ (earth radius+shuttle altitude )
                         = 6371 / (6371 + 240)
          footprint angle= 15.5 degrees.

So a shuttle at an altitude of 240 kms over 28.4 N latitude can see to the
north as far as 28.4 + 15.5 = 43.9 degrees. Eg a Shuttle over the Sahara
Desert in Africa can just see the South of France.

To be able to see UK from a 28.4 deg inclination orbit the Shuttle must
fly at a minimum altitude of 549 kms ie beyond Shuttles designed flight
envelope. Even the American Freedom Space Station , which will have a 28.4
deg inclination, will not fly high enough to see or be seen in UK , except
for that sunny little detached bit of UK called the Channel Islands where
there is a slight chance of having Freedom absolutely on the horizon once
each day.

Of all the Shuttle flights so far only 2 or 3 have actually overflow UK,
and a couple more have gone south of UK and been visible from UK. These
orbits had to have inclinations of about 40 degrees minimum, and this is
very expensive in launch fuel because you lose more than half of the one
thousand miles per hour assist from the earth's easterly spin. Worse still
orbits inclined above 50 degrees which launch from Florida, come
dangerously close to overflying the big cities of Americas Eastern
seaboard, during the dodgy early post launch part of the flight. So they
are not popular.

At present the Shuttle program is badly upset with a backlog of flights
built up because of hydrogen leaks. So it is not possible to predict when
the next high inclination flight will appear over UK. When it is due to
launch, be assured G3RWL of Amsat UK and others will give you plenty of
warning. Meanwhile in respect of the announcements /pronouncements from
the Republic of S Yorks, the old security advice of " Burn before reading
" is highly appropriate. 73 de John GM4IHJ@GB7MAC