3/21/91: SPACE STATION FREEDOM RESTRUCTURING PLAN COMPLETED
RELEASE: 91-45
NASA today delivered the "restructuring" report to the
Congress, outlining an extensive redesign of the Freedom space
station. The new design is cheaper, smaller, easier to assemble in
orbit and will require fewer Shuttle flights to build.
Major new features of the redesigned space station - shorter
U.S. laboratory and habitat modules that can be outfitted and
verified on the ground and a pre-integrated truss that can be
assembled on the ground and tested with all of its subsystems
intact - will significantly reduce intravehicular activity (IVA)
and on-orbit extravehicular activity (EVA) needed to build and
maintain Freedom.
"This new design for Space Station Freedom accomplishes every
major goal we set for ourselves when we kicked off this effort last
November," said William B. Lenoir, Associate Administrator for
Space Flight. "We took the directions from Congress and the
Augustine Commission recommendations to heart, and the program we
are announcing today addresses each and every one of their
requirements.
"We've cut costs, simplified the design and reduced the
complexity of the project. At the same time, Freedom will be a
quality facility, providing a research laboratory unsurpassed in
the world for life sciences and microgravity research, and a
stepping stone into the future, enabling NASA to conduct the
research and planning necessary for human exploration of the solar
system. And, we have maintained our international commitments," he
continued.
A 1991 fiscal year budget shortfall of more than $550
million, along with Congressional directions to significantly
reduce out-year spending, prompted NASA to begin the restructuring
of Freedom. Congress told NASA to expect no more than 8 to 10
percent growth over the next 5 years (FY 1992-1996), with peak
spending for Freedom not to exceed $2.5-2.6 billion. The budgetary
ground rules, including the cut for FY 1991, represent a $5.7
billion shortfall from what NASA had planned to spend for Freedom
over that same time period.
NASA directed the review in November 1990 with instructions
to the Freedom project team to: develop a phased approach with
quasi-independent phases; protect life and materials science;
maintain international agreements and capability; limit assembly
flights to no more than four annually; and achieve first element
launch, man-tended capability and permanently manned capability as
early as possible.
The restructured program calls for the first element launch
of the space station to be made in the second quarter of FY 1996
(January - March 1996), and man-tended capability to be achieved in
the third quarter of FY 1997 (April-June 1997).
In the man-tended phase, astronauts brought up to Freedom by
the Space Shuttle will be able to work inside the U.S. laboratory
for periods of 2 weeks. They will return to Earth with the
Shuttle. At this stage, one set of Freedom's solar arrays will
generate about 22 kw of power with a minimum of 11 kw available to
users. Six Shuttle flights will be required to achieve the
man-tended configuration.
Freedom will achieve a permanently manned configuration in
Fiscal Year 2000. This configuration will consist of the U.S.
laboratory and habitat, as well as the European and Japanese
laboratories; the Canadian Mobile Servicing System; accommodations
for a live-in crew of four; and three sets of solar arrays
furnishing 65 kw of electrical power, with a minimum of 30 kw going
to the users and the remainder to housekeeping chores.
A new requirement before permanently occupying the station
will be the availability of an Assured Crew Return Vehicle to
return space station crew members to the Earth in an emergency.
Seventeen Shuttle flights will be needed to build the permanently
manned configuration.
Provisions to expand the space station have been maintained.
The follow-on phase of the Freedom program will include another
solar array to achieve 75 kw, provisions for 4 additional crew
members and could include additional capabilities such as a second
preintegrated laboratory and additional nodes. This phase would
use the new launch system for launch and assembly if the launch
system is available.
The redesigned U.S. lab and hab modules are 27 feet long and
14.5 feet in diameter, about 40 percent shorter than the previous
design. The smaller size allows the modules to be fully outfitted
and tested on the ground prior to being launched into orbit. The
U.S. lab module will hold a total of 24 8-foot wide racks, 15 of
which initially are devoted to scientific work. At permanently
manned capability, 28 experiment racks will be available to U.S.
investigators: 12 in the U.S. lab, 11 in the ESA lab and 5 in the
Japanese lab.
The redesigned truss segments will be built, preassembled and
checked out on the ground. Formerly, the truss was to have been
assembled, like a massive erector set, by astronauts performing
space walks. NASA estimates the pre-integrated truss will cut
assembly EVA by more than 50 percent.
While work on the Attached Payload Accommodations Equipment
(APAE) suitable for large external payloads has been stopped,
utility ports for small external payloads will be placed along the
truss. The overall width of the station has been reduced from 493
feet to 353 feet.
Complexity of other station systems also has been reduced and
where possible, hardware already flying on the Space Shuttle will
be used in place of developing new hardware for the station. Also
called for in the plan is the transfer of the Flight Telerobotic
Servicer to NASA's Office of Aeronautics, Exploration and
Technology. This, together with the deferral of the APAE, has
eliminated the Goddard Space Flight Center's Work Package 3 from
the Freedom program.
In addition to changes to the flight hardware, a number of
changes to ground facilities are planned. The Space Station
Processing Facility to be built at the Kennedy Space Center will
not be fully outfitted, and a new hazardous processing facility
has been deleted in favor of using an existing facility. The size
of planned facilities at the Johnson Space Center - the control
center and crew training facilities - have been scaled back.
Payload facilities at Marshall Space Flight Center are being
deferred and existing facilities will be used in the interim.
Due to funding cutbacks and hardware changes in the program,
some layoffs of prime and subcontractor personal have already taken
place, and more are expected. At Work Package 1, no layoffs at the
prime contractor, Boeing, are expected, but more than 500 people
will be reduced from the subcontractor roles, some of which will be
accommodated through transfers and attrition.
At Work Package 2, prime contractor McDonnell Douglas has
already reduced its work force by about 160, with half that number
being layoffs. Major subcontractors to McDonnell Douglas will be
reduced by about 470, with layoffs accounting for approximately
half of that, and another 200 will be reduced from supporting
development, with about 65 of that total coming from terminations.
At Work Package 4, no layoffs are expected, but as many as 40
people in support jobs at Lewis Research Center will be reassigned.
Layoffs of about 30 percent of the work force at the Space Station
Engineering and Integration Contractor, Grumman, were announced
earlier this month.
SPACE STATION FACT SHEET
SPACE STATION FREEDOM WORK PACKAGES
SPACE STATION FREEDOM WORK PACKAGE ONE
NASA's Marshall Space Flight Center (Work Package 1) has
responsibility for: the design and construction of Space Station
Freedom's pressurized laboratory and habitation modules, the
working area and living quarters for Freedom's crew members; the
logistics modules, used for resupply and storage; node structures,
which connect the laboratory and habitation modules; and certain
subsystems internal to the pressurized modules, including the
environmental control and life support, thermal control, electrical
distribution, communcations and audio/video systems.
UNITED STATES LABORATORY AND HABITATION MODULES
The U.S. Laboratory Module and Habitation Module will each be
14.5 feet in diameter and 27 feet in length. These dimensions
allow the modules to be built, outfitted, integrated and tested on
the ground and then transported into Earth orbit in the Space
Shuttle cargo bay and connected to the nodes and other space
station structures.
The U.S. Lab will include 15 experiment racks and 13 systems
racks. During the station's Man-Tended Capability (MTC) phase,
this orbiting laboratory will serve as the site for microgravity
research and will be capable of conducting that science in both a
manned mode, when astronauts are visiting the station via the Space
Shuttle, and in an unmanned mode. When station construction
reaches Permanently Manned Capability (PMC) and four astronauts
remain onboard for extended periods, life sciences research will be
conducted to learn more about the affects of living in space and to
help prepare mankind for returning to the Moon and exploring the
planets.
With the addition of the Habitation and International
Laboratory modules, the station's module racks will expand to as
many as 45.
When station construction reaches PMC and the Hab Module is
added, Freedom's environmental control and lifes support systems
will provide closed-loop water recycling capability. The crew's
food and other supplies will be carried to the station via a
logistics module which is transported in the Space Shuttle's cargo
bay. During the Man-Tended Capability phase, astronauts visiting
Freedom will live on the Shuttle.
SPACE STATION FREEDOM WORK PACKAGE TWO
NASA's Johnson Space Center (Work Package 2) Space Station
Freedom Program Office (SSPO) is responsible for the design,
development, verification, assembly and delivery of the Work
Package 2 flight elements and systems, which include: the
pre-integrated truss assembly; propulsion assembly; Mobile
Servicing System transporter; resource node design and outfitting;
external thermal control; data management; communication and
tracking; extravehicular systems and guidance; navigation and
control systems, and the airlock.
JSC SSPO is also responsible for the attachment systems
required by the Space Shuttle for periodic visits. In addition,
JSC SSPO provides technical direction to the Work Package 1
contractor via the Marshall Space Flight Center for the design and
development of all manned space subsystems.
PRE-INTEGRATED TRUSS ASSEMBLY
The pre-integrated truss assembly is the Space Station
Freedom structural framework to which the modules, solar power
arrays and mobile transporter will be attached.
PROPULSION ASSEMBLY
The propulsion assembly will be used to adjust or maintain
the orbit of Space Station Freedom to ensure it remains at the
required altitude. Work Package 2 has responsibility for the
overall propulsion system.
MOBILE TRANSPORTER SYSTEM
The Mobile Servicing System will be a multi-purpose mechanism
equipped with a transportable robotic arm used to help assemble and
maintain Space Station Freedom. The Work Package 2 contractor will
build the mobile transporter; Canada will provide the robotic arm
and a special-purpose dexterous manipulator.
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.
EXTRAVEHICULAR ACTIVITY 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. An airlock for use by crew members performing EVA will
also be designed as part of Work Package 2.
EXTERNAL THERMAL CONTROL
The external thermal system provides primary cooling and heat
rejection to control temperatures of electronics and other Space
Station hardware located throughout the facility.
ATTACHMENT SYSTEMS
In concert with the Orbiter Projects Office, Work Package 2
is responsible for the development of systems which will permit
Space Shuttle mating with the Space Station.
GUIDANCE, NAVIGATION AND CONTROL SYSTEM
The GN&C system is composed of 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 orbiter mating operations and trajectories determination
of vehicles and objects which may intersect the orbit of the Space
Station.
COMMUNICATIONS AND TRACKING SYSTEM
The communications and tracking (C&T) system is composed of
six subsystems: space-to-space communications with crew members
during space walks (EVA); aboard the Space Shuttle, and with
visiting vehicles such as the European Space Agency man-tended
free-flyer; space-to-ground communications through the Tracking
and Data Relay Satellite System (TDRSS) to ground data networks;
internal and external voice communication through the audio
subsystem; internal and external video requirements through the
video subsystem; management of communication and tracking
resources and data distribution through the control and monitor
subsystem; and navigation data through the tracking subsystem.
DATA MANAGEMENT SYSTEM
The data management system (DMS) 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 acquisition
and distribution, data storage, and the user interface to permit
control and monitoring of systems and experiments.
ASSURED CREW RETURN CAPABILITY
Crew safety is an essential consideration in the development
of the Space Station to the permanently-manned configuration. 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 an Assured Crew Return Vehicle (ACRV) which would be used to
supplement the Space Shuttle in such circumstances.
WORK PACKAGE TWO CONTRACT
McDonnell Douglas Space Systems Company's Space Station
Division heads a team completing the work for Work Package 2.
Major subcontractors include GE Aerospace Government Communications
Systems Division, Honeywell Space Systems Group, IBM Federal Sector
Division, Lockheed Missiles and Space Company and Astro Aerospace.
GE is producing communications and tracking, Honeywell is working
on stabilization and controls, IBM is designing the data management
systems, Lockheed is developing thermal control, power management
and distribution, and extravehicular activity systems, and Astro is
responsible for the mobile transporter system.
SPACE STATION FREEDOM WORK PACKAGE FOUR
NASAUs Lewis Research Center, Cleveland, Ohio, is responsible
for the end-to- end electric power system for the Freedom space
station. This includes defining the system architecture and
providing the solar arrays, batteries, and power management and
distribution hardware and software. 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 22 kW of electric power
for a man-tended configuration, and 65 kW for a permanently manned
configuration with growth to 75.0 kW.
POWER GENERATION
Initially, power for Freedom will be provided by flexible,
deployable solar array wings. This configuration minimizes the
complexity of the assembly process by taking advantage of the
technology previously demonstrated on Space Shuttle flights. Each
39-by-122 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 deployable mast. A tension mechanism will
supply tension to the blanket as it reaches complete extension. The
entire wing will be tied structurally to the pre-integrated truss
by means of the beta gimbal assembly.
In order to provide the power needed during the period of
space station assembly, two solar wings, the energy storage system
and electronics components are assembled into a power module
scheduled to be carried up on the first space staion assembly
flight. These two wings along with engergy storage will provide 22
kW of power. The remaining power modules with two solar array
wings per module will be delivered on oribit after the man-tended
configuration is reached.
POWER STORAGE
Nickel Hydrogen (Ni-H2) batteries will store the energy
produced by the solar arrays. A battery pack is made up of 76
Ni-H2 cells, wiring harness, and mechanical/thermal. support
components. On discharge, the battery provides power to the
primary bus for eclipse periods. Ni-H2 batteries were selected for
low weight and high reliability.
POWER MANAGEMENT AND DISTRIBUTION (PMAD)
The 160/120 volt DC PMAD system is designed specifically to
meet the high electric power system requirements of the space
station. It is user friendly and can accommodate a wide variety of
user loads delivering controlled power to many scattered loads.
The high voltage DC power system was selected to provide high
efficiency, low cost, and safe operations.