STS-92 Day 4 Highlights
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- On Saturday, October 14, 2000, 6:00 a.m. CDT, STS-92 MCC Status Report # 6
reports:
- Discovery^Òs crew is set to install the first of two major
components that it carried to the Space Station today ^Ö a unique
piece of hardware called the Z1 truss. The truss is an exterior
framework that houses gyroscopes and communications equipment and
later will serve as a mounting platform for large solar arrays that
will provide power to the International Space Station.
- Earlier this morning, space station flight controllers in Houston
successfully activated and checked out controllers and power sources
for Unity^Òs common berthing mechanism, preparing it for the Z1
installation. Discovery^Òs robot arm will be powered up at 7:37
a.m. by NASDA astronaut Koichi Wakata and Mission Specialist Mike
Lopez-Alegria. Wakata will maneuver the arm to the Z1 truss in
Discovery^Òs payload bay, grappling the box-like frame about 8:20
a.m.
- A series of capture latches that secures the truss in place will be
commanded open and Wakata will gently raise the Z1 out of the payload
bay. With the truss firmly in its grip, the arm will be maneuvered to
a position called low hover and will remain during a final inspection
to ensure that all seals and petals on the common berthing mechanism
are properly aligned for the final installation. Commander Brian Duffy
will maneuver Discovery into the proper orientation for installation
as the Z1 is moved to its capture position. A series of four
^Óready to latch^Ô indicators are the signal for Discovery^Òs
crew to issue the final capture command, and the Z1 truss should be
attached to the Space Station shortly after 10 a.m. today.
- Using a laptop computer, Pilot Pam Melroy will command 16 bolts to
tighten in a four-stage process to secure the Z1 truss to the Unity
module, as Wakata releases the Shuttle^Òs robot arm and moves it
back to its cradled position alongside the payload bay. Final
connections and outfitting work for the Z1 truss will be accomplished
by space-walking astronauts Bill McArthur, Leroy Chiao, Jeff Wisoff
and Mike Lopez-Alegria. Sunday, during the first of four scheduled
spacewalks for this flight, McArthur and Chiao will connect a series
of power cables, an S-band communications assembly, install a Space to
Ground Antenna and boom assembly and install an EVA tool stowage box
on the port side of the structure.
- With the Z1 installation complete, the astronauts will enter the
Zarya module to transfer equipment and supplies for the first resident
crew expected to arrive later this month. McArthur and Chiao will
configure Discovery^Òs middeck in preparation for Sunday^Òs
spacewalk, staging some of the tools, tether and hardware they will
use during their planned 6½-hour EVA.
- The next Mission Control Center status report will be issued at 7
p.m. CDT or as events warrant.
- On Saturday, October 14, 2000, 8:00 p.m. CDT, STS-92 MCC Status Report # 7
reports:
- The crew of Discovery added nine tons of critical equipment to the
International Space Station today, attaching a framework that holds
motion control gyroscopes and communications equipment and that will
serve as a support for a giant set of solar arrays to be launched on
the next Space Shuttle flight.
- Japanese Astronaut Koichi Wakata, at controls in the shuttle
cockpit, deftly maneuvered Discovery's robotic arm to lift the
framework, called the Z1 truss, out of the shuttle's payload bay and
berth it to a port on the station's Unity connecting module. The
berthing was the first time the U.S.-developed attachment system has
been used in orbit, and the equipment worked flawlessly. Over the
course of the station's future assembly, similar attachment systems
will be used over 100 times. Astronaut Mike Lopez-Alegria, looking out
of the berthing port's hatch window in Unity, provided Wakata with
visual cues as to the framework's alignment.
- The berthing occurred about two hours behind schedule due to a
short-circuit aboard the shuttle early in the crew's day that cut off
power to some equipment Wakata would need. The short cut power to
three pieces of equipment: an Orbiter Interface Unit that provides
data and commanding from the shuttle to station systems; an Orbiter
Space Vision System that provides a computerized alignment aid for
operating the robotic arm; and a television camera located at the
bottom, or keel, of the payload bay that faces upward to provide a
supplementary visual cue for maneuvering the truss structure. Flight
controllers and the crew quickly developed a plan to use backup
equipment and alternate power to regain all functions except the keel
camera, and Wakata began lifting the truss from the shuttle bay about
2 hours and 15 minutes later than originally planned.
- The backup arrangement worked perfectly. The electrical bus that
experienced the short will remain powered off and will have no impact
on the rest of the mission's activities. Wakata latched the truss to
the station at 1:20 p.m. as the complex flew 240 statute miles above
southern Russia.
- Because activities were behind schedule following the morning
workaround, flight controllers opted to defer the transfer of some
gear from the station's Unity module to the Zarya module until the
crew next enters the station, planned for day nine of the mission. In
Unity, Pilot Pam Melroy and crewmate Jeff Wisoff opened the hatch
where the new truss was attached and, inside a pressurized dome,
installed grounding connections between the framework and the
station. Afterward, the crew exited the station, and, at 5:57
p.m. CDT, Lopez-Alegria and Commander Brian Duffy sealed the station's
outermost hatch.
- Duffy and Melroy then lowered Discovery's cabin pressure in
preparation for a space walk by astronauts Leroy Chiao and Bill
McArthur planned to begin at 9:32 a.m. Sunday. Reducing the cabin
pressure from a sea-level pressure of 14.7 pounds per square inch
(psi) to a pressure of about 10.2 psi is part of a protocol that
purges nitrogen from the space walker's body to prevent decompression
sickness. Chiao and McArthur spent the last couple of hours of their
day preparing equipment in the shuttle's lower deck and airlock for
tomorrow's venture outside the cabin. During the space walking
construction work, the first of four space walks planned during
Discovery's mission, the two will connect electrical and computer data
cables between the newly attached truss and Unity and deploy two
communications antennas from the truss.
- The crew begins a sleep period at 9:17 p.m. today and will awaken at
5:17 a.m. Sunday to begin preparations for the six and a half-hour
space walk. The next Mission Control Center status report will be
issued at 6 a.m. CDT or as events warrant.
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