Benefits
of the International Space Station William
H.Gerstenmaier National Aeronautics and
Space Administration (NASA) The International Space
Station (ISS) is rapidly approaching completion of the assembly phase with all
core elements successfully integrated and functionally verified on-orbit. The
program will soon transition to its full utilization phase. This paper briefly
summarizes the intangible benefits brought about through this unprecedented
global partnership, and elaborates on the tangible benefits associated with ISS
operations and utilization. The future potential of the ISS is at least as
great as the engineering achievements already in hand. Introduction The ISS represents the culmination
of over two decades of dedicated effort by an international team spanning
Canada, Europe, Japan, Russia and the United States. Working in unison on
design, development, assembly and operations in space has set new standards for
international cooperation and engineering of human rated space systems. With
this leap forward in human space operations come many benefits. The intangible
benefits are quickly recognized but difficult to quantify with precision. Nonetheless, such benefits are
real and indeed at the very basis of the human drive to achieve ever-increasing
levels of performance. Alternatively, the tangible benefits are practical,
measurable and unambiguous. The tangibility of ISS is readily apparent when one
compares early concept designs with the physical reality of an approximately
500 metric ton permanently crewed, full-service space platform that is now
operating at an altitude of Benefits can also be viewed
retrospectively and prospectively. The benefits of the ISS to date are largely,
although not exclusively, in the realm of space systems engineering and
operations, while future benefits extend into the vast domains of science and
applications. This latter aspect was captured succinctly by prior NASA Administrator,
Michael Griffin, when he remarked ":it will be the most unique laboratory
anyone has ever created. If we use it properly, if funds are appropriated to
allow us to use it properly, we will not fail to make ground-breaking
discoveries. We do not know what those are, but we know that we will not fail
to make such discoveries." The path of science and applications can change
abruptly with the emergence of a disruptive technology. The ISS is
unquestionably a highly capable scientific laboratory and engineering
technology test bed operating in an extraordinarily unique natural environment.
The future is promising. Intangible
Benefits While the intangible benefits are
well established and frequently cited, it is useful to quickly review the full
scope. These can be generally characterized as: (1) exploring the unknown; (2)
human inspiration; (3) international cooperation; (4) global leadership; (5)
industrial growth, and; (6) educational stimulation. Each has unique features
that contribute to a collective benefit that could be attributed to all of
space exploration and development, but in this instance is focused on the most
recent plateau of achievement - the ISS. Since the emergence of
civilization, exploring the unknown has
been a hallmark of progressive societies. It has also been a hallmark of NASA,
and our global space agency partners, and is documented in detail in the NASA
history series of the same title. It's a rich history that spans human and
robotic exploration and discovery across half a century. The reward for
exploring the unknown lies in discovery and the awareness that each new finding
brings us one step closer to understanding our world and reaping the benefits
of new knowledge. In the case of ISS, exploration may be actually learning to
assemble, operate and maintain a large facility in space, since we are learning
what is required to live off our planet. Traveling and living in space has
consistently evoked a strong sense of public inspiration, because it offers hope in a future that
involves humankind's evolution outward into our universe. Young and old alike
aspire to this adventure and achievement. ISS crewpersons are among the most
sought after personalities for appearances at events ranging from elementary
schools to retirement homes. The hopes and aspirations of these public
audiences are embodied in their desire to live vicariously through the life
experiences of space explorers. The ISS program has been
undertaken by a global alliance that assesses international cooperation at the highest of values. Such an
assessment is justified because it recognizes that the efforts of many nations
acting together compound to multiply the performance achieved and benefits
derived. ISS partners have transcended geopolitical challenges through their cooperative
relations. Barriers in distance, language, culture, technological maturity,
engineering standards, economic competitiveness, industrial capacity, and
nationalism have been overcome, thus setting new standards for future
international cooperative endeavors in science and technology. ISS taught us
that we must be willing to compromise purely nationalist goals for the greater
goals of space exploration. This compromise provided a diversity in
capabilities that was not achievable as an individual country. In terms of technological leadership, the ISS
is among the greatest human achievements in history. Each global partner has
increased their national proficiency in the ability to live and work in the
remote and hostile environment of space. This was accomplished through mutual
education in an atmosphere of collective problem solving. As a result, leadership has been
unequivocally established in large scale space systems integration - a
technical aptitude that simply did not exist prior to the ISS program. The
magnitude of the space and ground systems involved in ISS operations, and
distributed across North America, Europe and Asia, far exceeds that of any
prior civil endeavor. The techniques employed in assembly of the ISS, and
supported by space vehicles from around the world, have been of an engineering
complexity heretofore never imagined. ISS required acceptance of technical
standards unique to each of the countries involved and allowed for different
approaches from each country. This required NASA to look at these standards and
to judge them equivalent to US standards, although very different. The completed ISS represents an
opportunity for industrial growth that
can be characterized by creation of economies involving unique applications. It
will be operated as an "industrial commons", where private firms can access a
new environment for R&D of products and services. This is evidenced by two
recent initiatives that foreshadow what is to come in the next decade. In one
instance, NASA has begun a transition to commercial cargo resupply services
(CRS) that involves procurement of services from entrepreneurial companies that
have undertaken private development of space vehicles. In another case, NASA
will procure commercial water supplies that are based on recycling of ISS waste
carbon dioxide through the Sabatier technique. We have already entered into
agreements with several private firms that will use the ISS for R&D
purposes, and have issued a public announcement-of-opportunity to remain
indefinitely open to further proposals. Finally, any endeavor of this
scope requires individuals with extensive training in science, technology,
engineering and math (STEM). By their very nature, programs of this magnitude stimulate education as they
provide career opportunities for students at the undergraduate, graduate and
post-doctoral levels. In parallel, for primary and secondary school levels,
younger students have the chance to participate in human space flight through
televised broadcasts, experiments and personal visits by program personnel. To
date, over 30 million students have had the opportunity to receive ISS
broadcasts. While the number of students stimulated to pursue STEM careers
cannot be reliably estimated, it is nonetheless obvious that interest levels are
high and widespread. Tangible
Benefits The tangible benefits of the ISS
program are too extensive to address in a summary fashion. The balance of this
paper thus turns to those outcomes in two general categories: (1) NASA
mission-driven research; and (2) research applied to US national needs. The
former includes those benefits that accrue directly to NASA while in pursuit of
its primary mission to explore space, while the latter encompasses US needs for
R&D to advance national goals in fields that, although not directly related
to space, stand to benefit from the advanced technologies and access to space
environments afforded by the ISS. NASA Mission-Driven Research Human
Biomedical Research The ISS is NASA's only long-duration
flight analog for future human missions involving long transit times. It
provides an invaluable laboratory for research with direct application to risks
associated with missions beyond low Earth orbit (LEO). The ISS is being used to
identify and quantify risks to human health and performance, identify and
validate potential risk mitigation techniques, and develop countermeasures for
future missions. The ISS crew is conducting research to develop knowledge in
areas of clinical medicine, human physiology, cardiovascular performance, bone
and muscle health, neurovestibular medicine, diagnostic instruments and
sensors, exercise and pharmacological countermeasures, food and nutrition,
immunology and infection, and human behavior. Engineering Technology Development The ISS provides a unique
opportunity to flight test components and systems in the space environment and
optimize subsystem performance. It is the only space-based test-bed available
for critical systems such as closed-loop life support, EVA suits, energy
storage, and automated rendezvous and docking. Characterizing and optimizing
system performance in space reduces mission risks and yields next-generation
capabilities for long distance and autonomous vehicle and systems management. As a direct result of the ISS
Program, the inventory of space qualified materials, piece-parts, components,
assemblies, subsystems, and systems is expanding rapidly. Developing confidence in systems
for water and waste recovery, oxygen generation, and environmental monitoring
is important as the distance and time away from Earth is extended. The ISS will
be used to demonstrate closed-loop life support for oxygen and water systems.
In Mission Operations Research Demonstration and validation of the human-machine interfaces
enable sustained spacecraft operations over long periods of time. Advances in
crew and robotic operations, on-orbit maintenance and repair, in-space
assembly, and demonstrations of crew and cargo transportation vehicles are
essential to venture beyond LEO. Assembling six major truss segments, eight
solar array wings, and four laboratory modules with interconnecting nodes
demonstrates the precision and coordination necessary for in-space assembly of
large structures. Autonomous rendezvous and docking capabilities, essential to
complex future space missions, are demonstrated through launch vehicles that
transport crew and cargo to ISS. These vehicles currently include the Space
Shuttle, Russian Soyuz and Progress spacecraft, and the new European Automated
Transfer Vehicle (ATV) and Japanese H-II Transfer Vehicle (HTV). In the future, U.S. Commercial Resupply Service (CRS) vehicles
are also anticipated. The ISS robotic arms provide the ability to assemble large
elements in flight, while ground control of robotic activities enables more
efficient use of valuable crew time. The 55-foot-long robotic arm can move Development of displays and controls is important for future
spacecraft system designs. Software tools play a role in helping crews
virtually practice EVA, or robotic tasks, before they ever don spacesuits. More
than 50 computers control on-board systems, and use some 2.5 million lines of ground
software code to support 1.5 million lines of flight software code. Standard
communication protocols control crew displays and software tools, while common
flight software products, tools, interfaces, and protocols enhance operational
practices. ISS provides a real-world laboratory for logistics management
and inflight maintenance and repair concepts for future spacecraft. These
techniques demonstrate an ability to evolve and adapt through daily operations.
Common component designs simplify sparing systems and are used to minimize the
number of spares stored on orbit (e.g., common valve design). Interoperable
hardware systems include the common berthing mechanism, utility operations
panel, international standard payload racks, orbital replacement units, crew
equipment, and robotic grapple fixtures. Through thousands of days of operating experience, the ISS is
demonstrating the maintainability and reliability of hardware components.
Models used to predict this reliability and maintainability are enhanced by
measuring the mean-time-between failure performance on hundreds of components,
including pumps, valves, sensors, actuators, solar arrays, and ammonia loops.
ISS crews have had to demonstrate repair capabilities on internal and external
systems and components, as well as hardware not originally designed for
on-orbit repair. Repairs have been performed on malfunctioning space suits,
computers, treadmill bearings, oxygen generators, carbon dioxide scrubbers,
solar arrays, beta gimbals, radiators and remote power control modules. The
crews and their ground maintenance counterparts have devised unique solutions
that have kept the ISS functioning, including remote maintenance and
sustainability procedures, and inspection and repair techniques. This
experience has helped identify design flaws and re-deploy improved systems to
orbit. The ISS provides valuable lessons for current and future
engineers and managers -- real-world examples of what works and what does not
work in space. Developing methods to work with our partners on the ground and
in space is critical to providing additional capabilities and solutions to
design challenges. Research Applied to U.S.
National Needs As we transition from the assembly phase to the full
utilization phase, the ISS will be operated as a US national laboratory and
thus made available to other US government agencies, academic institutions,
private firms and non-profit institutions. At that stage, the benefits will
extend beyond NASA and begin accruing in areas related to US national needs
for: (1) improvement in human health; (2) environmental research; (3) energy
systems research. Improvement in Human Health Improvement in human health is the mission of the US National
Institutes of Health (NIH). Consistent with this, the NIH entered into a
memorandum of understanding with NASA to use the ISS for research. In Spring
2009, NIH issued a three year rolling announcement for research grants in areas
including: (1) cancer; (2) heart, lung and blood disorders; (3) aging; (4)
arthritis and musculoskeletal and skin diseases; (5) biomedical imaging and
bioengineering; (6) child health and human development; and, (7) neurological
disorders and stroke. Research is scheduled to begin by the close of Environmental Research At the macro level, ISS began serving as an Earth observation
platform when the first crew arrived and began using handheld cameras to
photograph the Earth. The spatial resolution that can be achieved is comparable
to, or better, than many satellites and under certain conditions a spatial
resolution of These observations will be used to develop and test techniques
for remote sensing of the neutral atmosphere and ionosphere on a global scale.
The package is an array of eight limb-scanning optical instruments covering the
wavelength region 550 - 8700 Angstroms. The experiment scans the limb of the
Earth to measure profiles of airglow from major species in the upper
atmosphere. Measurements will be used to determine the composition and
temperature of the thermosphere and ionosphere. It will be the most
comprehensive survey of the ionosphere and thermosphere in over 20 years. At
the micro level, ISS represents among the most sophisticated engineering test
beds in the world for oxygen regeneration and water reclamation. A urine
processor assembly handles up to Energy Systems Research The ISS is a test bed for research on energy generation,
storage and distribution technologies. The continuing series of Materials on
ISS Experiments (MISSE) provides a way to test different solar cell materials
for accelerated exposure to radiation, atomic oxygen, extremes of heat and
cold, and other factors. The Forward Technology Solar Cell Experiment (FTSCE)
characterized 36 different solar cell types. A follow-on experiment is
scheduled to fly soon. The results will lead to more efficient and durable
solar cells for future applications. In the area of energy storage, ISS
currently employs nickel-hydrogen batteries that will wear out and need
replacement, so the ISS will convert to use of higher density lithium ion (Li+)
batteries. While Li+ batteries are currently used on the ground at very
low energy density levels (e.g., cell phones and calculators), the ISS program
will advance technology by demonstrating Li+ battery components capable of much
greater energy densities. In terms of power transmission, the ISS represents a
suitable platform for the demonstration of microwave, or laser optic,
transmission technologies. Space-to-space power relays have obvious
applications to future space missions, as well as to ground systems involving
power generation that is remote from urban loads. Conclusion The benefits afforded by the ISS are both intangible and
tangible. The intangibles are well known and quickly recognized. Since the
future course of science and applications is impossible to predict, the
complete range of tangible benefits will only emerge as R&D progresses, and
often many years after the initial discovery. Nonetheless, in the history of
science and engineering, new discoveries and subsequent applications have
inevitably followed the emergence of disruptive new technologies. As we begin the 21st century, the ISS represents an
extraordinary leap forward in civil space technology, and the future potential
is at least as great as the engineering achievements already in hand. |
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