STS-103 PAYLOADS
Servicing Mission 3A Configuration
 | | Discovery's
payload bay with Hubble servicing cargo. |
Centered
in Discovery's cargo bay is the Orbital Replacement Unit Carrier.
The carrier is a modified Spacelab pallet that contains the tools
and replacement parts (see below) necessary to service the Hubble
Space Telescope. Also, inside the cargo bay is the Flight Support
System that will hold the telescope during servicing. Once the
Hubble is attached to the support system, the system can rotate
the telescope for appropriate access during spacewalks.
Rate Sensor
Units (Gyroscopes)
The Rate
Sensor Units allow the Telescope to point at stars, planets
and other celestial targets. There are three aboard Hubble, and
each unit contains two gyroscopes. Hubble needs three of these six
gyroscopes to meet its very precise pointing requirements, and the
other three are spares. Astronauts will replace all three units,
leaving Hubble with six fresh gyroscopes. (MPEG
Video Format - 1.5 M)
Fine Guidance
Sensor
This is the second in a "round-robin" series of changeouts and refurbishments
of the three fine guidance sensors, which allow fine pointing and
keep Hubble stable. The SM3A refurbished Fine
Guidance Sensor is the same unit that was returned from Servicing
Mission 2. The Fine Guidance Sensor returned from this mission will
be refurbished and upgraded for re-use on Hubble's fourth Servicing
Mission. (MPEG
Video Format - 1.5 M)
New Spacecraft
Computer
The radiation-rugged computer will replace Hubble's original, outdated
main computer. The new
computer will dramatically increase operational capabilities,
reduce the burden of flight software maintenance, and significantly
lower operational costs. (MPEG
Video Format - 1.0 M)
Voltage/Temperature
Improvement Kits
As Hubble's batteries age, they become more susceptible to overheating
if overcharged. The Voltage/Temperature
Improvement Kit compensates for this by lowering the battery's
charge termination voltage. Astronauts will install one kit for
each of Hubble's six batteries.
Spare S-Band
Single Access Transmitter
The transmitter
replaces an aged and failed unit. That unit will be removed, returned
to Earth and refurbished for a later flight. (MPEG
Video Format - 1.0 M)
Spare Solid
State Recorder
The digital
data recorder will serve as a high capacity backup to the Solid
State Recorder that replaced a mechanical tape recorder in 1997.
It is essential for efficiently handling the high volumes of data
from Hubble's newest instruments and for maintaining high science
productivity.
New Outer Blanket
Layer
Stainless
steel sheets will be installed in various locations on the telescope
to help control Hubble's internal temperature. Covered with a protective
thermal coating, these sheets will fit over existing insulation
that has degraded. The following three tasks below will be performed
on SM3A, time permitting. If there is insufficient time, these tasks
will be completed on SM3B. (MPEG
Video Format - 1.5 M)
Shell/Shield
Replacement Fabric
Flexible aluminized
Teflon sheets will be added to the exterior
surfaces of Hubble's forward shell and light shield. This protective
covering provides additional insulation against the harsh space
environment. (MPEG
Video Format - 0.7 M)
Aft
Shroud Latch Repair Kit
During Servicing
Mission 2 on STS-61,
astronauts observed galling on latches caused by high torque.
The STS-103 astronauts will replace these latches on Hubble's
bay door.
Handrail
Covers
Fiberglass cloth, called beta cloth, will be
fitted like sleeves around the handrails above the Fine Guidance Sensors bay to prevent
contamination to the Aft Shroud area. Flaking paint was observed
on these handrails during Servicing Mission 2. | 
