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"6_10_2.TXT" (13431 bytes) was created on 12-07-87
WORK PACKAGE 1
Marshall Space Flight Center is responsible for Space
Station Program Work Package 1, including responsibility for the
laboratory module, habitation module, logistics elements and
fabrication of the primary structure for the resource nodes.
Marshall also is responsible for development of the environmental
control and life support system, internal components of the
audio/visual and thermal control systems, as well as for
operational capability development for users in the laboratory
module. The Johnson Space Center, through special provisions
within the Work Package 1 contact, will exercise technical
direction for the manned space subsystems.
LABORATORY MODULE
The U.S. laboratory module will be cylindrical, measuring
approximately 44 feet long and 14 feet in diameter and will
provide a shirt-sleeve environment for performing laboratory
functions. The laboratory module will be capable of supporting
multi-discipline payloads including materials research and
development activities, materials processing demonstrations, life
sciences research and other space science investigations
requiring a pressurized area. User-provided equipment that can
be housed in the laboratory module include furnaces for growing
semiconductor crystals, electrokinetic devices for separating
pharmaceuticals, support equipment needed to carry out a wide
spectrum of low-gravity experiments and applications, and a
centrifuge for variable gravity experiments in life sciences.
HABITATION MODULE
Facilities for eating, sleeping, personal hygiene, waste
management, recreation, health maintenance and other functions
requiring pressurized space will be provided in the habitation
module. The module will be the same size as the laboratory
module and will accommodate up to 8 astronauts.
Using the health maintenance facility, astronauts will be
able to monitor their health through vital signs, X-rays and
blood samples. There also will be exercise equipment for daily
physical conditioning.
LOGISTICS ELEMENTS
These include elements required for transporting cargo to or
from the Space Station for the resupply of items required for the
crew, station, and payloads; and for on-orbit storage of these
cargos. A key element will be the pressurized logistics carrier,
which will carry items used inside the Space Station modules.
The other elements include unpressurized logistics carriers used
for transporting spares used external to the Space Station
modules, fluids and propellants.
ENVIRONMENTAL CONTROL AND LIFE SUPPORT SYSTEM (ECLSS)
The ECLSS will provide a shirt-sleeve environment for the
astronauts in all pressurized modules on the Space Station. A
key feature is the regenerative design employed in the air
revitalization and water reclamation systems.
RESOURCE NODE STRUCTURE
The resource nodes are required to interconnect the primary
pressurized elements of the manned portion of the Space Station
and also will house certain key control functions. The equipment
provided by Work Package 1 consists of the resource node
structures, berthing mechanisms, racks, ECLSS, internal thermal
control, and internal audio and video communication systems.
WORK PACKAGE 2
NASA's Johnson Space Center is responsible for the design,
development, verification, assembly and delivery of the Work
Package 2 Space Station flight elements and systems, which
include the integrated truss assembly, propulsion assembly,
mobile servicing system transporter, resource node design and
outfitting, external thermal control, data management, operations
management, communication and tracking, extravehicular systems
and guidance, navigation and control systems, and the airlocks.
JSC also is responsible for the attachment systems to the STS for
its periodic visits. Additionally, JSC is responsible for flight
crews, crew training and crew emergency return definition, and
for operational capability development associated with operations
planning. JSC will provide technical direction to the contractor
for the design and development of all manned space subsystems.
INTEGRATED TRUSS ASSEMBLY
The integrated truss assembly is the Space Station
structural framework to which the modules, solar power arrays,
external experiments, Earth- and astronomical-viewing
instruments, and mobile transporter will be attached.
PROPULSION ASSEMBLY
The propulsion assembly will be used to adjust or maintain
the orbit of the Space Station to keep it at the required
altitude. Work package 2 has responsibility for the overall
propulsion system. Technical direction for the thruster assembly
elements of the propulsion system will be provided by MSFC.
MOBILE TRANSPORTER SYSTEM
The mobile servicing system will be a multi-purpose
mechanism equipped with robotic arms to help assemble and
maintain the Space Station. The contractor will build the mobile
base; Canada will provide the mobile servicing system which
includes robotic arms and special purpose dextrous manipulators.
RESOURCE NODES
The resource nodes house most of the command and control
systems for the Space Station as well as being the connecting
passageways for the habitation and laboratory modules. Work
Package 2 will outfit the node structures provided by Work
Package 1 to accomplish the objectives of each node.
EVA SYSTEMS
Extravehicular activity (EVA) systems includes equipment
such as the extravehicular mobility unit (EMU) or spacesuit,
provisions for communication, physiological monitoring, and data
transmission, EVA crew rescue and equipment retrieval provision,
and EVA procedures. Airlocks for crewmember extravehicular
activity also will be designed as part of Work Package 2.
EXTERNAL THERMAL CONTROL
The external thermal system provides cooling and heat
rejection to control temperatures of electronics and other Space
Station hardware located outside the modules and nodes.
ATTACHMENT SYSTEMS
In addition to devices permitting Space Station docking by
the Space Shuttle and logistics resupply modules, this includes
systems for attaching experiment packages and other external
hardware to the truss structure.
GUIDANCE, NAVIGATION AND CONTROL SYSTEM (GN&C)
The guidance, navigation and control system is composed of a
core system and traffic management functions. The core system
function provides attitude and orbital state maintenance,
supports the pointing of the power system and thermal radiators,
accomplishes periodic reboost maneuvers, and provides Space
Station attitude information to other systems and users.
The traffic management function provides for controlling all
traffic in the area around the Space Station, including docking
and berthing operations and trajectories determination of
vehicles and objects which may intersect the orbit of the Space
Station.
COMMUNICATIONS AND TRACKING SYSTEM (C&T)
The communications and tracking system is composed of six
subsystems: space-to-space communications with crew members
during extravehicular activity, aboard the Space Shuttle, and
with the Orbital Maneuvering Vehicle; space-to-ground
communications through the Tracking and Data Relay Satellite
System to ground data networks; internal and external voice
communication through the audio subsystem; internal and external
video requirements through the video subsystem; management of C&T
resources and data distribution through the control and monitor
subsystem; and navigation data through the tracking subsystem.
DATA MANAGEMENT SYSTEM (DMS)
The data management system provides the hardware and
software resources that interconnect onboard systems, payloads,
and operations to perform data and information management.
Functional services provided by DMS include data processing, data
acquistion and distribution, data storage, and the user interface
to permit control and monitoring of systems and experiments.
Crew safety is an essential consideration in the development
of the Space Station. A major system failure aboard the Space
Station, injuries or illness may require the return of crew
members to Earth during a period when the Space Shuttle is
unavailable. NASA's Johnson Space Center has responsibility for
conducting definition-phase studies of a Crew Emergency Return
Vehicle which could be used to supplement the Shuttle in such
circumstances.
WORK PACKAGE 3
NASA'S Goddard Space Flight Center is responsible for
development of several of the Station's elements including the
free-flying platforms and attached payload accommodations, and
for planning NASA's role in satellite servicing. Goddard also
has responsibility for developing the Flight Telerobotic Servicer
which is being procured through a separate competition.
FREE-FLYING PLATFORMS
Goddard will manage the detailed design, development, test
and evaluation of the automated free-flying polar platform. This
unmanned platform will feature modular construction to permit on-
orbit ease of serviceability and flexibility for accommodating a
variety of scientific observations.
ATTACHED PAYLOAD ACCOMMODATIONS
The Space Station attached payloads are the instruments and
experiments designed to gather scientific data while attached
directly to the truss framework of the Space Station. Goddard is
responsible for providing utilities such as power, thermal
control, data handling, pointing stability and other equipment
needed to operate the payloads and for insuring that the
instruments are pointed at the intended targets. Two attachment
points are provided, one of the attach points is fixed and the
other has an articulated pointing system.
FLIGHT TELEROBOTIC SERVICER
Goddard is responsible for building the Flight Telerobotic
Servicer. This system will be capable of in-space assembly of
Station elements and payload servicing.
As the system is evolved, it will perform telerobotic
servicing and repair of spacecraft visiting the Space Station.
In the future, a telerobotic servicer-equipped Orbital
Maneuvering Vehicle could retrieve, as well as service,
spacecraft beyond the Space Station's orbit.
WORK PACKAGE 4
Lewis Research Center is responsible for the end-to-end
electric power system architecture for the Space Station and for
providing the solar arrays, batteries, and common power
distribution components to the platforms.
The power system includes power generation and storage, and
the management and distribution of power to the final user
interface. The electric power system is required to have the
capability to deliver 75 kW of electric power with a growth
potential to 300 kW.
POWER GENERATION
Initially, Space Station power will be provided by eight
flexible, deployable solar array wings. This configuration
minimizes the complexity of the assembly process by taking
advantage of the technology demonstrated on Space Shuttle
flights. Each 32- by 96-foot wing consists of two blanket
assemblies covered with solar cells. These are stowed in blanket
boxes which are attached to a deployment canister. Each pair of
blankets is to be deployed and supported on a coilable,
continuous longeron mast. A tension mechanism will supply
tension to the blanket as it reaches complete extension. The
entire wing will be tied structurally to the transverse boom by
means of the beta gimbal assembly.
To provide the power needed during the period of Space
Station assembly, two solar wings and other elements of the power
system are scheduled to be carried up on each of the first two
Space Station assembly flights. These four wings will provide
37.5 kw of power. The remaining four panels will be delivered on
orbit after the permanently-manned configuration is reached.
Lewis also is responsible for developing and testing proof
of concept hardware for the solar dynamic power module to prepare
for the growth phase of the Station. In addition, sufficient
preliminary design efforts will be performed to insure that the
Space Station can accommodate the solar dynamic modules.
POWER STORAGE
Ni-H2 batteries will store the energy produced by the solar
arrays. A battery pack is made up of 23 Ni-H2 cells, wiring
harness and mechanical/thermal support components. On
discharge, this operates near 28 v which allows the flexibility
to connect several packs in series to obtain a high voltage
system for the Space Station and platforms or use of single
packs as a candidate for other low voltage applications. Ni-H2
batteries offer minimum weight and high reliability with minimum
redundancy required for the polar platform. During the eclipse
periods, power is supplied by the energy storage systems.
POWER MANAGEMENT AND DISTRIBUTION (PMAD)
The 20 kHz PMAD system is designed specifically to meet
aerospace requirements. It is based upon rapid semiconductor
switching, low stored reactive energy, and cycle-by-cycle control
of energy flow, allowing tailoring of voltage levels. It is user
friendly and can easily accommodate all types of user loads.
The PMAD system will deliver controlled power to many
scattered loads. The high frequency ac power system was selected
to provide higher efficiency, lower cost and improved safety.
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