yee@trident.arc.nasa.gov (Peter E. Yee) (08/08/89)
Lisa Malone
Kennedy Space Center August 7, 1989
KSC Release No. 80-89
COLUMBIA MODIFICATIONS AND IMPROVEMENTS
About 258 modifications have been performed on Columbia
since it last flew in Jan. 1986 on mission 61-C, including the
list of critical return-to-flight vehicle improvements and about
16 that are unique to Columbia.
The return-to-flight modifications made to Columbia now
bring the vehicle up to par with the other two orbiters,
Discovery and Atlantis. These extensive improvements include the
crew escape system, a latch to hold the 17-inch disconnect valve
between the orbiter and external tank open during powered flight,
wiring improvements and new thrusters in the forward reaction
control system and orbital maneuvering system pods to prevent a
burn through of the thrusters.
To decrease brake wear, the axles were stiffened on the
landing gear. Instrumentation has been added to monitor the tire
pressure once the landing gear doors are closed. About a dozen
extra clamps were added to Columbia's hydraulic braking lines
which demonstrated a higher vibration than that of the other
ships.
Larger protective tiles have been installed in the elevon
leading edge and wing trailing edges to improve flight durability
and decrease turnaround maintenance. Columbia's payload bay doors
and fuselage were originally covered with small white diced
tiles. Since it last flew, technicians have replaced over 2,300
of these diced tiles with thermal protective blankets like those
on the other two ships. In addition, Columbia features the
reinforced carbon-carbon "chin panel." This panel replaces about
40 tiles between the nose cap and nose landing gear doors and is
designed to better withstand heat loads during reentry. A
significant amount of the worn interior thermal control blankets
was replaced.
Columbia, which flew the first five flights of the Shuttle
program, features more instrumentation than the other two ships
for research and development. Much of the instrumentation will be
hooked up during its eighth flight, including about 400 strain
gauges on the wings, payload bay doors and vertical stabilizer to
monitor loads, pressures and temperatures during flight. For
aerothermal analysis, about 140 sensors have been installed on
the wing area.
After STS-9 in Nov. 1983, Columbia was sent to Palmdale,
Calif. for about 18 months to reconfigure the ship from a
research and development mode to an operational orbiter. Five
major modifications were made during this timeframe: (1)
structural beefup of the wings and mid-fuselage; (2) addition of
a heads-up-display; (3) the replacement of the commander and
pilot's ejection seats with standard seats; (4) modification of
the orbital maneuvering system pods to make them compatible with
the other orbiters, including replacement of the pod's thermal
tiles with the advanced reusable surface insulation blankets; and
(5) addition of supplemental instrumentation to gather
developmental engineering data.
An infrared imaging device on Columbia's vertical
stabilizer, called the Shuttle Infrared Leeside Temperature
Sensing (SILTS) experiment, will be active on this flight. This
cylindrical housing atop the vertical tail was added in Palmdale
after STS-9, and is about 20-inches in diameter. It is designed
to obtain high-resolution infrared images of the upper (leeside)
surfaces of Columbia's port wing and fuselage as the orbiter
reenters Earth's atmosphere. These images will provide detailed
temperature maps of those surfaces to indicate the amount of
aerodynamic heating in flight.
Another experiment, called Shuttle Entry Air Data System
(SEADS), housed in the nosecap will also be active this flight.
The nose cap has 14 penetration assemblies distributed about its
surface, each containing a small hole through which local surface
air pressure will be measured during reentry. This experiment is
expected to provide aerodynamic flight characteristics.
Other improvements include upgrades to the electrical
system, upgraded cockpit computer keyboards, new fuel cells and
new auxiliary power unit controllers. A newly modified liquid
hydrogen recirculation pump package has been installed to prevent
electrical shorting.
The new modifications have added approximately 2,500 pounds
of extra weight since Columbia last flew. Columbia's dry inert
weight with three main engines (but no payload, experiments or
propellants) is approximately 179,833 pounds.