Launch from Cape Canaveral (
KSC); landing on Cape
Canaveral (
KSC). The
launch was originally set for July 23, 1991 but was moved to July 24, 1991 to
allow time to replace a faulty integrated electronics assembly that controls
orbiter/external tank separation. Mission postponed again about five hours
before liftoff on July 24, 1991 due to a faulty main engine controller on
number three main engine. The launch was reset for August 1, 1991. Due to cabin
pressure vent valve reading and due to unacceptable return-to-launch site
weather conditions the launch was postponed again.
Primary payload,
Tracking and Data Relay Satellite-5 (
TDRS-5 or
TDRS-E)
attached to an Inertial Upper Stage (IUS), deployed about six hours into
flight, and IUS propelled satellite into geosynchronous orbit;
TDRS-5
becomes fourth member of orbiting
TDRS
cluster.
Secondary payloads were Space Station Heat Pipe Advanced
Radiator Element II (SHARE II); Shuttle Solar Backscatter Ultra-Violet (SSBUV)
instrument; Tank Pressure Control Equipment (TPCE) and Optical Communications
Through Windows (OCTW). Other experiments included Auroral Photography
Experiment (APE-B) Protein Crystal Growth Ill (PCG Ill); Bioserve /
Instrumentation Technology Associates Materials Dispersion Apparatus (BIMDA);
Investigations Into Polymer Membrane Processing (IPMP); Space Acceleration
Measurement System (SAMS); Solid Surface Combustion Experiment (SSCE);
Ultraviolet Plume imager (UVPI); and the Air Force Maui Optical Site (AMOS)
experiment. The SHARE II experiment tested a natural cooling process for
transferring thermal energy that could serve as a cooling system for the future
Space Station.
The crew was kept busy with the operation of varied
experiments during the mission. The crew experienced some minor problems, none
of them critical to the safety or success of the mission. A cooling system for
Auxiliary Power Unit (APU) 2 failed to activate during an on-orbit test. APU 2
is one of three redundant systems which provide hydraulic pressurization to
orbiter steering systems during entry and landing. APU 2 was still available
for use in landing.