yee@trident.arc.nasa.gov (Peter E. Yee) (05/22/91)
[I will be on travel, vacation, and other leave until 17 June 1991, so during
that period there will be no status reports in sci.space and sci.space.shuttle
from NASA. I will save the reports and post them upon my return. -PEY]
KSC SHUTTLE STATUS REPORT - TUESDAY, MAY 21, 1991 - 1 PM
STS-40/SPACELAB LIFE SCIENCES 1 - COLUMBIA (OV 102) - PAD 39-B
LAUNCH - POSTPONED UNTIL LATE NEXT WEEK
WORK IN PROGRESS:
- Preparations to replace the multiplexer demultiplexer, 9
cryogenic propellant temperature transducers and general purpose
computer no. 4.
- Access to the aft compartment.
- Reconnection of the orbiter midbody umbilical to the orbiter.
This unit was used to deliver reactants to the orbiter's fuel
cell storage tanks and will be used to offload propellants.
- Preparations to disconnect ordnance devices.
WORK COMPLETED:
- Activation of the orbiter's communications systems.
- Preparing the tail service masts on the launch platform for
launch. Liquid oxygen and liquid hydrogen propellants are loaded
into the external tank through these masts.
FLIGHT CREW:
- STS-40 crew will be leaving for Houston early tomorrow morning.
CONCERNS:
Officals decided to postpone the launch until late next week
while the launch team replaces and retests the 9 temperature
transducers, the multiplexer demultiplexer and general purpose
computer no. 4.
After failure analysis recently conducted by the vendor in
New Hampshire, officials decided to replace the nine cryogenic
temperature transducers in the main propulsion system. There is a
concern they could break off as the propellant is flowing through
the main propulsion system and wind up in the main engines.
The multiplexer demultiplexer (MDM) is one of 23 and is lo-
cated in the orbiter's aft compartment bay 5. MDMs receive and
translate data from the orbiter's general purpose computers to
critical systems. This particular MDM FA 2 controls functions for
solid rocket boosters, orbiter hydraulic systems, ordnance
devices and the orbital maneuvering system and reaction control
system.
General purpose computer No. 4 is one of 5 and is located in
the orbiter's crew cabin.