Thermal
Protection System
Various materials applied
to the outer structure protect the orbiter from excessive heat.
- Overview
- Seven different materials,
chosen for their weight efficiency and stability at high temperatures,
are used.
- Reinforced
Carbon-Carbon
- RCC protects areas where
temperatures exceed 2,300 degrees F during entry.
- High-Temperature
Reusable Surface Insulation Tiles
- Black tiles are applied
on areas where temperatures do not exceed 2,300 degrees F.
- Fibrous
Refractory Composite Insulation Tiles
- Black tiles developed
later in the program replace some HRCI tiles.
- Low-Temperature
Reusable Surface Insulation Tiles
- White tiles are used in
areas where temperatures do not exceed 1,200 degrees F.
- Advanced
Flexible Reusable Surface Insulation Blankets
- Quilted composite fabric
replaced most of the LRSI tiles.
- Felt
Reusable Surface Insulation
- Nomex felt blankets are
used on the payload bay doors and other areas where temperatures
do not exceed 700 degrees F.
- Thermal
Barriers
- Various materials are
used to fill in gaps.
- Tile
Identification
- Each tile has a unique
ID code.
- Flags
and Letters
- Flags and letters are
painted on.
- Rewaterproofing
- After each flight the
orbiter is rewaterproofed.
- Contractors
- List of contractors for
the thermal protection system.
Main Propulsion
System
Along with SRBs, provides
velocity increment necessary to reach orbit.
- Overview
- The main propulsion system
includes three main engines, controllers and supporting equipment.
- Orbiter
Main Propulsion System Helium Subsystem
- Helium is used to purge
tanks and actuate valves.
- Main
Propulsion System Propellant Management Subsystem
- Liquid hydrogen and liquid
oxygen are fuels used by the system.
- External
Tank
- The external tank feeds
fuel to the main propulsion system.
- Space
Shuttle Main Engines
- The main engines are reusable,
high-performance, liquid-propellant rocket engines with variable
thrust.
- Pogo
Suppression System
- A pogo suppression system
prevents engine thrust oscillation.
- Space
Shuttle Main Engine Controllers
- Each controller operates
in conjunction with other components to provide a self-contained
system for engine control, checkout and monitoring.
- Malfunction
Detection
- There are three separate
means of detecting malfunctions within the main propulsion system.
- Orbiter
Hydraulic Systems
- Three hydraulic systems
supply pressure to the main propulsion system, providing thrust
vector control and actuating engine valves on each SSME.
- Thrust
Vector Control
- Ascent thrust vector control
directs thrust of the main engines and SRBs to control attitude
and trajectory from liftoff through second-stage ascent.
- Helium,
Oxidizer and Fuel Flow Sequence
- The complete sequence
begins several hours before launch and ends after main engine cutoff.
- Main
Propulsion System Contractors
- List of contractors.
Orbiter/External
Tank Separation System
Includes system components
on both sides of the separation.
- Overview
- When the external tank
separates from the orbiter, several components act at once for a
clean disconnect.
- 17-inch
Disconnect
- Mated pairs of disconnects
contain valves that allow propellant to flow until time for ET separation.
- External
Tank Separation System
- The external tank is separated
from the orbiter at three structural attach points.
- Orbiter
Umbilical Doors
- After external tank jettison,
doors close the umbilical cavities.
Orbital
Maneuvering System
The orbital maneuvering system
provides the thrust for orbit insertion, circularization, orbit transfer,
rendezvous, and deorbit.
- Overview
- The OMS is housed in two
independent pods located on each side of the orbiter's aft fuselage.
- Helium
Pressurization
- The OMS system uses helium
to pressurize fuel tanks.
- Propellant
Storage and Distribution
- OMS propellant tanks enable
the orbiter to reach a 1,000-foot-per-second velocity change.
- Engine
Bipropellant Valve Assembly
- Each OMS engine receives
pressure-fed propellants at its bipropellant valve assembly.
- Engine
Thrust Chamber Assembly
- The thrust chamber is
where the fuel and oxydizer react in the injector.
- OMS
Thrusting Sequence
- The OMS thrusting sequence
commands the OMS engines on or off and commands the engine purge
function.
- Engine
Thrust Vector Control System
- The engine TVC system
consists of a gimbal ring assembly, two gimbal actuator assemblies,
and two gimbal actuator controllers.
- Thermal
Control
- OMS thermal control is
achieved by insulation in the OMS pods and strip heaters.
- OMS-RCS
Interconnect
- OMS propellant can be
used to operate the Reaction Control System.
- OMS-to-RCS
Gauging Sequence
- The OMS-to-aft-RCS propellant
quantities are calculated by burn time integration.
- Abort
Control Sequences
- The abort control sequence
software manages OMS and RCS configuration and thrusting periods
during ascent aborts.
- OMS
Engine Fault Detection and Identification
- The OMS engine FDI function
detects and identifies off-nominal performance of the OMS engine.
- OMS
Gimbal Actuator FDI
- The OMS gimbal actuator
FDI detects and identifies off-nominal performance of the pitch
and yaw gimbal actuators of the OMS engines.
Reaction
Control System
The RCS units provide the
thrust for pitch, yaw and roll maneuvers and for small velocity changes
along the orbiter axis.
- Overview
- The forward and aft RCS
systems consist of helium storage tanks, pressure systems, propellant
systems, and thermal control.
- Pressurization
System
- Gaseous helium supplies
pressure to the fuel and oxidizer tanks.
- Propellant
System
- A system of tanks, lines
and valves distributes propellant to the RCS thrusters.
- RCS
Quantity Monitor
- Onboard computers calculate
the usable percent of fuel and oxidizer in each RCS module.
- Engine
Propellant Feed
- Isolation valves control
the amount of propellant being fed to each RCS module.
- RCS
Engines
- Each RCS engine contains
a fuel and oxidizer valve, injector head assembly, combustion chamber,
nozzle and electrical junction box.
- Heaters
- Heaters maintain propellant
and pod temperatures within safe operating ranges.
- RCS
Jet Selection
- Based on crew commands,
the onboard computers direct RCS burns.
Electrical
Power System
EPS subsystems work together
to provide electrical power to the vehicle during all mission phases.
- Overview
- The EPS consists of three
subsystems: power reactant storage and distribution, fuel cell power
plants, and electrical power distribution and control.
- Power
Reactant Storage and Distribution
- Cryogenic hydrogen and
oxygen are stored in specially-equipped tanks.
- Fuel
Cell Power Plants
- The fuel cells are located
under the payload bay area and in the forward portion of the orbiter's
midfuselage.
- Electrical
Power Distribution and Control
- The EPDC subsystem distributes
28-volt dc electrical power and generates and distributes 115-volt,
three-phase, 400-hertz ac electrical power to all of the space shuttle
systems' electrical equipment throughout all mission phases.
Environmental
Control and Life Support System
ECLSS systems interact to
provide a habitable environment for the flight crew and cooling or heating
for various orbiter systems and components.
- Overview
- The ECLSS consists of
atmosphere and water treatment and thermal systems.
- Crew
Compartment Cabin Pressurization
- The cabin is pressurized
to 14.7 psia and maintained at an average 80-percent nitrogen and
20-percent oxygen mixture by the air revitalization system.
- Cabin
Air Revitalization
- There are five independent
air loops in the cabin.
- Water
Coolant Loop System
- The WCLS provides thermal
conditioning of the crew cabin by collecting heat at a heat exchanger
and transferring it to the water coolant loops.
- Active
Thermal Control System
- The ATCS consists of Freon
interchangers, radiators and heat exchangers to control thermal
conditions.
- Supply
and Waste Water
- The supply and waste water
systems provide water for the flash evaporator, crew consumption
and hygiene.
- Waste
Collection System
- The waste collection system
is an integrated, multifunctional system used primarily to collect
and process biological wastes from crew members in a zero-gravity
environment.
- Waste
Water Tank
- A single waste water tank
receives waste water from the ARS humidity separator and the waste
collection system.
- Airlock
Support
- The airlock and airlock
hatches permit EVA flight crew members to transfer from the middeck
crew compartment into the payload bay in EMUs without depressurizing
the orbiter crew cabin.
- Extravehicular
Activity Mobility Units
- EMU space suits provide
the necessities for life support during space walks.
- Crew
Altitude Protection System
- The crew altitude protection
system is worn by the flight crew members during launch and entry.
- Radioisotope
Thermoelectric Generator Cooling and Gaseous Nitrogen Purge for
Payloads
- A cooling and purge system
is installed in Discovery and Atlantis to support those payloads
with RTGs or gaseous nitrogen purging requirements.
Auxiliary
Power Units
The orbiter has three APUs,
hydrazine-fueled, turbine driven power units produce pressure for the
vehicle's hydraulic systems.
Water Spray Boilers
The water spray boiler system
consists of three identical independent water spray boilers, one per
corresponding auxiliary power unit and hydraulic system.
Hydraulic
System
The hydraulic system consists
of three independent systems, each providing mechanical shaft power
to drive a hydraulic pump.
Landing
Gear System
Each landing gear includes
a shock strut with two wheel and tire assemblies.
- Overview
- The landing gear system
on the orbiter is a conventional aircraft tricycle configuration
consisting of a nose landing gear and a left and right main landing
gear.
- Main
Landing Gear Brakes
- Each of the orbiter's
four main landing gear wheels has electrohydraulic disc brakes and
an anti-skid system.
- Nose
Wheel Steering
- The orbiter nose wheel
is steerable after nose wheel touchdown at landing.
Caution and
Warning System
Designed to provide the crew
with both visual and aural cues when a system exceeds predefined operating
limits.
- Orbiter
Lighting System
- The orbiter lighting system
provides both interior and exterior lighting.
- Smoke
Detection and Fire Suppression
- Smoke detection and fire
suppression capabilities are provided in the crew cabin avionics
bays, the crew cabin and the Spacelab pressurized module.
- Payload
Deployment and Retrieval System
- The payload deployment
and retrieval system includes the electromechanical arm that maneuvers
a payload from the payload bay of the space shuttle orbiter to its
deployment position and then releases it.
- Payload
Retention Mechanisms
- Non-deployable payloads
are retained by passive retention devices, and deployable payloads
are secured by motor-driven, active retention devices.
Communications
Ground-based, orbiter and
satellite systems are employed to keep the crew in touch with Mission
Control.
- Space
Flight Tracking and Data Network
- Provides tracking, data
acquisition and associated support.
- Tracking
and Data Relay Satellite System
- Provides continuous global
coverage of Earth-orbiting satellites at altitudes from 750 miles
to about 3,100 miles.
- Orbiter
Communications
- Transfers telemetry information,
commands, documentation and voice communications.
- Overview
- Information is transferred
through hardline and radio frequency links.
- S-Band
System
- Operates in the S-band
portion of the RF spectrum of 1,700 to 2,300 MHz.
- Ku-Band
System
- Used only when the
orbiter is on orbit.
- Ku-Band
Rendezvous Radar
- Ku-Band system includes
a rendezvous radar that skin-tracks satellites and other rendezvous
targets.
- Payload
Communication System
- Used to transfer information
between orbiter and its payloads.
- Ultrahigh
Frequency System
- Used as a backup fro
S-Band PM and Ku-Band voice communications, primarily for EVAs.
- Audio
System
- Interfaces with caution/warning
system, UHF, S-Band, Ku-Band, and tacan systems.
- Instrumentation
- Several camera systems
are used by the flight crew to document activities during the mission.
- Overview
- Used to collect, route
and process information throughout the orbiter and its payloads.
- Pulse
Code Modulation Master Unit
- Receives data from
MDMs and formats them for transmission to the ground.
- Network
Signal Processor
- Responsible for processing
and routing commands, telemetry and voice between the orbiter
and the ground.
- Ground
Command Interface Logic
- Also referred to as
the ground command interface logic controller.
- General-Purpose
Computer and Communication Interface
- Computers process
communication controls and provide a command path between the
ground and orbiter subsystems.
- Master
Timing Unit
- A stable crystal-controlled
timing source for the orbiter.
- Operational
Recorders
- Used for serial recording
and dumping of digital voice and PCM data.
- Payload
Recorder
- Records and dumps
payload data through S-Band or Ku-Band transmitter.
- Teleprinter
- Interim system designed
tro transmit written data from the ground to the crew.
- Text
and Graphics System
- Fax scanner on the
ground that sends text and graphics to hard copier in orbiter.
- Close-Circuit
Television System
- Used to support on-orbit
activities that require visual feedback to the crew.
- Operational
Recorders
- Used for serial recording
and dumping of digital voice and PCM data.
- Orbiter
Experiments Support Systems for OV-102 (Columbia)
- Records data obtained
through OEX sensors.
- Shuttle
Infrared Leeside Temperature Sensing
- Obtains high-resolution
infrared imagery of orbiter surfaces during atmospheric entry.
- Shuttle
Entry Air Data System
- takes measurements
required for precise determination of air data during launch
and landing phases.
- Shuttle
Upper Atmosphere Mass Spectrometer
- Obtains measurements
of free-stream density during atmospheric entry.
- Aerodynamic
Coefficient Identification Package
- A group of sensors
palced on the orbiter to obtain experiment measurements unavailable
through the baseline system.
- High-Resolution
Accelerometer Package
- Measures low-level
aerodynamic accelerations along the orbiter's principal axed
during re-entry.
- Modular
Auxiliary Data System
- Measures and records
selected pressure, temperature, strain, vibration and event
data.
Avionics
Systems
Controls,
or assists in controlling, most of the shuttle systems.
Overview
Controls, or assists in
controlling, most of the shuttle systems.
Data
Processing System
The vehicle relies on
computerized control and monitoring for successful performance.
- Software
- DPS software is divided
into two major groups: system software and applications software.
- General-Purpose
Computers
- Five identical computers
aboard the orbiter control vehicle systems.
- Mass
Memory Units
- Computing functions
for all mission phases requires about 400,000 words of computer
memory.
- Multifunction
CRT Display System
- Displays on the flight
deck allow onboard monitoring of systems, software processing
and manual control for crew data and software manipulation.
- Master
Timing Unit
- The GPC complex requires
an accurate time source because its software uses GMT to schedule
processing.
- Computer
Data Bus Network
- Network is divided
into specific groups that perform specific functions.
- Multiplexers/Demultiplexers
- DPS MDMs convert and
format serial digital GPC commands into separate commands for
various vehicle system hardware.
- Master
Events Controllers
- Send signals to arm
and safe pyrotechnics during SRB/ET separation.
- Data
Bus Isolation Amplifiers
- Interfacing devices
for the GSE/LPS and SRB MDMs.
- Backup
Flight Control
- The fifth GPC, loaded
with different software, provides backup in case primary GPCs
fail.
Guidance,
Navigation and Control
GNC software commands
effect vehicle control and provide sensor data needed to compute
these commands.
- Flight
Control System Hardware
- Hard-wired to one
of eight flight-critical MDMs.
- Navigational
Aids
- Include IMUS, tacan
units, air data probe assemblies, and more.
- Inertial
Measurement Units
- Consist of an all-attitude,
four-gimbal, inertially stabilized platform.
- Star
Trackers
- Two star tracker units
are part of the navigation system.
- Crewman
Optical Alignment Sight
- Used if IMU alignment
is in error more than 1.4 degrees.
- TACAN
- Determine slant range
and magnetic bearing to ground station.
- Air
Data System
- Provides information
on the movement of the orbiter in the air mass.
- Microwave
Scan Beam Landing System
- Used during landing
phase to determine slant range, azimuth and elevation to landing
runway.
- Radar
Altimeter
- Measure absolute altitude
from the orbiter to nearest terrain within beamwidth of orbiter's
antennas.
- Accelerometer
Assemblies
- Sense vehicle acceleration
along lateral and vertical axes.
- Orbiter
Rate Gyro Assemblies
- Used by flight control
system to sense roll, pitch and yaw rates during ascent and
entry.
- Solid
Rocket Booster Rate Gyro Assemblies
- Used as feedback to
find rate errors from liftoff to SRB separation.
- Rotational
Hand Controller
- Used by flight crew
to gimbal engines and OMS/RCS systems.
- Translational
Hand Controller
- Used for manual control
of translation along the longitudinal, lateral, and vertical
axes to control RCS.
- Control
Stick Steering Push Button Light Indicators
- Indicate control stick
mode.
- Rudder
Pedals
- Command orbiter rotation
about the yaw axis by positioning the rudder during atmospheric
flight.
- Speed
Brake/Thrust Controller
- Used during ascent
to vary thrust level of main engines; used during entry to control
aerodynamic drag.
- Body
Flap Switches
- Provide manual control
for positioning body flap during entry.
- RHC/Panel
Enable/Inhibit
- Provide signals to
GPCs, prohibiting execution of related software commands while
RHC is active.
- Trim
Switches
- Used to move the aerosurfaces
in roll, pitch and yaw.
- Aerosurface
Servoamplifiers
- Receive commands during
atmospheric flight, causing aerosurface deflections.
- Digital
Autopilot
- Composed of several
software modules that interpret maneuver commands and generate
commands for the appropriate effectors.
- Rendezvous
Thrusting Maneuvers
- OMS/RCS thrusting
periods can be used to correct or modify the orbit as required.
- Component
Locations
- Black boxes are situated
in several locations around the orbiter.
Dedicated
Display Systems
Provide the flight crew
with data required to fly the vehicle manually or to monitor automatic
FCS performance.
- Attitude
Director Indicator
- Provide attitude data,
including attitude rates and errors.
- Horizontal
Situation Indicator
- Displays a pictorial
view of the vehicle's position.
- Alpha
Mach Indicator
- Display vehicle angle
of attack.
- Altitude/Vertical
Velocity Indicator
- Display vertical acceleration,
vertical velocity, barometric altitude and radar altitude.
- Surface
Position Indicator
- Displays actual and
commanded positions of elevons, body flap, rudder, aileron and
speed brake.
- Flight
Control System Push Button Indicators
- Transmit moding requests
to digital autopilot.
- RCS
Command Lights
- Indicate RCS jet comands
by axis and direction.
- G-Meter
- Senses linear acceleration
along the Z axis of the vehicle.
- Head-up
Display
- Optical miniprocessor
that cues the commander during final landing approach.
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