jallred@bbn.com (John Allred) (12/02/88)
In case anyone missed it, the Atlantis launch was scrubbed because of bad weather. Reset those orbital predictions accordingly. ____ John Allred BBN Systems and Technologies Corp. (jallred@bbn.com) A truly wise man never plays leapfrog with a unicorn.
tif@cpe.UUCP (12/03/88)
In case anyone missed it, the Atlantis launch was successful THIS morning at about 0830 CST (0930 EST?) after a long wait for the weather. I didn't see any strange plumes this time either although the cameras weren't real helpful. That sure did look like a long roll though? Paul Chamberlain Computer Product Engineering, Tandy Corp. bellcore!motown!sys1!cpe!tif
karn@ka9q.bellcore.com (Phil Karn) (12/04/88)
> That sure did look like a long roll though?
As I predicted a few weeks ago, the roll maneuver was a good indication of
the launch azimuth, which in turn revealed the supposedly "secret" orbital
inclination.
The lowest inclination attainable from a given launch site is always
obtained by launching due east, and the resulting inclination is equal to
the site's latitude in degrees. For KSC this is 28.5 degrees. Any other
launch azimuth always results in a higher inclination.
The orbiter sits on the pad with the vertical stabilizer pointing due south,
but it must fly the ascent with the stabilizer pointing straight down.
Therefore a 28.5 degree inclination orbit (the minimum attainable) calls for
a roll maneuver of exactly 90 degrees so that the stabilizer will point down
as the shuttle pitches over to go downrange. However, a 57 degree
inclination orbit (the highest allowed from KSC for safety reasons) is
obtained with a launch azimuth of 35 degrees, so this calls for a roll angle
of 145 degrees -- 55 degrees more than usual.
Although the TV camera angles changed several times during the roll maneuver
(perhaps this was intentional? :-)) it was still obvious that the orbiter
was going into a high inclination orbit. The long duration of the roll, plus
sunlight angles before and after, were enough. An experienced observer at
the press site should also have been able to tell from the path of the SRB
exhaust plume -- a high inclination launch path would go more to the left as
seen from the site. An interesting exercise would be to compare a videotape
of yesterday's launch against that of an earlier low-inclination launch.
Phil