From: Neil T. Clifford <>
Date: Mon, 8 May 1995 22:34:50 -0400

AA> Alphonse: the last I heard, Atlantis was scheduled for launch sometime
AA> between June 19th and June 24th. I'm hopeful that this is the case
AA> since Mir will be coming back into the skies of the late evening for
AA> west European observers about this time ..... things could be looking
AA> up!

Things aren't quite so rosy. The targeted date has been (up until the
today Monday) 24 June (with no earlier than 19 June launch). The actual
date is dependant upon the Spektr launch (and its impact on the EVA's
and activity needed to juggle the modules prior to the STS mission).
Each days delay puts the launch back some 24 minutes or so in order that
Mir's orbital plane can be intercepted (I figure a 19 June launch at
2243 UTC will will translate to about 2045 UTC by 24 June). Thus the
launch times occur nearer to sunset with each passing day, and the
number of viewable passes during the mission is reduced. For 24 June the
shuttle would be best seen around central Europe; passes would be
visible up to about mission day 7, whilst in NW Europe only a handful of
low elevation passes for the first (approx.) 4 days would be viewable
and the ascent pass would occur only a few minutes after sunset. If
Spektr arrives at Mir on time, NASA may exercise an option to shorten
STS-70 (from 7 to 5 days); maybe they can realistically aim for the 19
June date then? If so the viewing improves substantially.

The 'upside' to a delay is the increased 'viewability' of the STS and ET
during ascent. As the days pass the launch time is earlier, the pass
closer to sunset and so the Earth's shadow height at the observer's
location lower resulting in a potentially longer illumination time for
the orbiter and ET (They look like being visible for a short time during
a 19 June launch for observers in Western Europe).

These are of course constrained by local sunset - beyond (approx.) the
end of June virtually all passes would be lost in the sunset and the early
evening daylight.

Incidentally Mir's evening apparitions will begin around 8 June but will
have died off by around 25 June.

(Apologies to all non-European readers for my indulging in this
regionalised description; though a similar argument applies to N.
Amercian viwers on the East coast as regards viewing the powered ascent
during the night [and passes during the mission for those in more
Northerly American locations]).

best wishes,

Neil Clifford
Received on Mon May 08 1995 - 22:22:45 UTC

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