yee@trident.arc.nasa.gov (Peter E. Yee) (04/23/91)
SPACE SHUTTLE MISSION STS-39 COUNTDOWN STATUS --- April 21, 1991
LAUNCH MINUS TWO DAYS
Everything at pad 39-A is continuing on schedule today as
launch team members work toward the launch of the Space Shuttle
Discovery at 7:05 a.m. Tuesday, April 23. The launch window
extends through 10:31 a.m.
The countdown clock came out of the T-27 hour planned eight-
hour built-in hold on time this morning at 8:45. The clock will
continue to count down until 4:45 p.m. today at which time it
will enter another planned built in hold.
Last night, final servicing of the STS-39 payloads was
completed and the payload bay doors were closed today at 8:30
a.m.
At the pad today, the Power Reactant and Storage
Distribution System on-board storage tanks are being serviced
with liquid hydrogen and liquid oxygen reactants. The pad clear
for this hazardous operation was given shortly after 9:00 a.m.
today.
Following PRSD loading operations, the orbiter midbody
umbilical unit is scheduled to be retracted at about 4:45 p.m.
today. Communication activation checks are then targeted to
commence at about 9:00 p.m. this evening. The Rotating Service
Structure is scheduled to be moved away from the vehicle at 11:45
a.m. Monday.
The STS-39 flight crew arrived at Kennedy Space Center at
about 6:30 p.m. Saturday. Today, the seven member crew, already
split into two teams to accommodate a 24-hour in-flight work
schedule, had their final medical exams and flew training
missions in the Shuttle Training Aircraft and T-38 trainer
aircraft.
Weather for Tuesday's liftoff is forecast to be less than
favorable with 70 percent chance of violating launch constraints
at the opening of the windown. There is a 60 percent chance of
violating constraints throughout the entire three-hour, 26-minute
window. A front located through western Florida and into the Gulf
will probably produce low clouds and favorable conditions for
showers.
Wednesday's forecast calls for a 60 percent chance of
violating launch constraints; Thursday's forecast calls for a 40
percent chance of violation.