Each of the initiatives described in the previous section is a worthwhile program. Although each has something different to offer, each falls within the framework of NASA’s vision, each builds on and extends existing capabilities, and each elicits the reaction, “America ought to be doing this.” In the absence of fiscal and resource constraints, the United States would undoubtedly adopt all four. In the presence of those very real constraints, and the additional constraints imposed by the current state of our civilian space program, this course of action is not possible.
In
its desire to revitalize the civilian space program, NASA must avoid the trap
identified by the Rogers Commission during its investigation of the Challenger
accident: “The attitude that enabled the agency to put men on the moon and
to build the Space Shuttle will not allow it to pass up an exciting challenge—even
though accepting the challenge may drain resources from the more mundane (but
necessary) aspects of the program.” The Commission further observed (in reference
to the Shuttle flight rates): “NASA must establish a realistic level of expectation,
then approach it carefully.”
To
establish a realistic level of expectation, NASA must consider the current
condition of the space program, its strengths and limitations, and its capabilities
for growth. Any bold initiative has to begin with and then build on today’s
space program, which unfortunately lacks some fundamental capabilities. For
example, our most critical commodity, Earth-to-orbit transportation, is essential
to each of the initiatives. But the Space Shuttle is grounded until at least
June of 1988, and when it does return to flight status, the flight rate will
be considerably lower than that projected before the Challenger accident (a
four-Shuttle fleet is estimated to be capable of 12 to 14 flights per year).
In
hindsight, it is easy to recognize that it was a crippling mistake to decree
that the Space Shuttle would be this country’s only launch vehicle. Several
studies since the Challenger accident have recommended that the civilian
space program include expendables in its fleet of launch vehicles. This
strategy relieves some of the burden from the Shuttle, gives the country a
broader, more flexible launch capability, and makes the space program less
vulnerable in the event of an accident.
The
problem of limited launch capability or availability will be magnified during
the assembly and operation of the Space Station. Currently, NASA plans to use
only the Space Shuttle to transport cargo and people to and from the Space
Station. This places a heavy demand on the Shuttle (six to eight flights per year),
but more important, it makes the Space Station absolutely dependent on the
Shuttle. If Shuttle launches should be interrupted again in the mid-1990s, this
nation must still have access to space and the means to transport cargo and
people to and from the Space Station. The importance of this capability was
emphasized by the National Commission on Space in its report, Pioneering the
Space Frontier: “Above all, it is imperative that the US maintain a
continuous ability to put both humans and cargo into orbit.”
TRANSPORTATION REQUIREMENTS
NASA transportation needs for the 1990s, and beyond received considerable attention from the task group and committees examining agency goals and future program thrusts. The consensus of their findings is that if the Nation is to open a "Highway to Space," we must regain regular and assured access to space and expand launch capacity based on expendable and reusable vehicles.
“NASA
should, on a most urgent basis, initiate a program to incorporate a diversified
family of expendable launchers into its space flight program, to include a
heavy-lift ELV. Payloads should be off-loaded from shuttle onto ELVs wherever
possible.” Report of the Task Force
on Issues of a Mixed Fleet, 1987
“The
U.S. should continue to expand its launch capacity based on a mixed fleet
of expendable and reusable launch vehicles to preclude total reliance on any
one launch system, so that the present manned and unmanned launchers will
remain operationally healthy until the next generation of vehicles is fully
developed.” U.S. Civil Space
Program: An AIAA Assessment, 1987
The use of a mixed launch fleet
will humans to fly when they are needed on a mission and allow unmanned vehicles
to be the carrier of choice for other missions... Diversity will also allow
a better matching of the scientific requirements of a mission with the launch
capability needed to meet those requirements, rather than forcing the mission
to meet the constraints of a single inflexible launch system.” The Crisis in Space and Earth Science, 1986
“The
shuttle fleet will become obsolescent by the turn of the century. Reliable,
economical launch vehicles will be needed to provide flexible, routine access
to orbit for cargo and passengers at reduced costs ... to reduce space operation
costs as soon as possible, the Commission recommends that three major space
transport needs be met in the next 15 years: cargo transport to low Earth
orbit; passenger transport to and from low Earth orbit; and round-trip transfer
beyond low Earth orbit.” Pioneering
the Space Frontier, 1986
From
now until the mid-1990s, Earth-to-orbit transportation is NASA’s most pressing
problem. A space program that can’t get to orbit has all the effectiveness
of a navy that can’t get to the sea. America must develop a cadre of launch
vehicles that can first meet the near-term commitments of the civilian space
program and then grow to support projected programs or initiatives.
Expendable
launch vehicles should be provided for payloads which are not unique to the
Space Shuttle—this is required just to implement current plans and to satisfy
fundamental requirements.
A
Shuttle-derived cargo vehicle should be developed immediately. A
Shuttle-derived vehicle is attractive because of its lift capacity, its
synergism with the Space Transportation System, and its potential to be
available for service in the early 1990s. This cargo vehicle would reduce the
payload requirements on the Shuttle for Space Station support and would
accelerate the Space Station assembly sequence.
The
United States should also seriously consider the advisability of a crew-rated
expendable to lift a crew capsule or a logistics capsule to the Space Station.
The logistics vehicle, for Space Station resupply and/or instrument return,
would be developed with autodocking and precision reentry capabilities. The
crew capsule would carry only crew members and supplies, would launch (with or
without a crew) on the expendable vehicle, would have autodocking capability,
and might also be used for crew rescue.
TECHNOLOGY
Rebuilding
the Nation’s technology essential for the successful achievement of any
long-tem space goal. It is widely that we are living off the interest of the
era technology investment, and that it is to replenish our technology reservoir
in to enhance our range of technical option.
“The
Nation has allowed its technology to erode, leaving it with little cap move out
in new directions should the arise.” Letter from Daniel J. Fink (Chairman, NASA
Advisory Council) to James Fletcher, dated August 14, 1986
“Space
technology advancement unlies any comprehensive future space activity. The
present course is a status-quo caretaker path with no potential growth. New
commitments are called for in key technologies such as propulsion, automation
and robotics, flight computers, information systems, sensors, power generation,
materials, structures, life support systems, and space processing. We support
the recommendation by the National Commission on Space for a three-fold increase
in this relatively low-budget but extremely important area of space technology.
advancement, especially in view of strong foreign commitments to such technology
development.” U.S. Civil Space Program: An AIAA Assessment, 1987
“Research must be pursued on a broad front,
to identify and quantify technical possibilities before their usefulness can be
judged. Such a research and technology program is therefore properly conceived
as opportunity generating, not directed toward applications.” Pioneering the
Space Frontier, 1986
These
transportation capabilities are required just to launch, assemble, operate, and
safely inhabit the Space Station, and to have some prospect of being able to
support future initiatives.
Without
sound, reliable Earth-to-orbit transportation available to lift sensors, spacecraft,
scientists, and explorers to orbit, we will not be in a position to aggressively
pursue either science or exploration. We have stated that transportation is
not our goal—but it is essential to the successful pursuit of whatever goals
we choose. If we do not make a commitment now to rebuild and broaden our launch
capability, we will not have the option of pursuing any of the four initiatives
described in the previous section.
The
same can be said for advanced technology. The National Commission on Space
observed that “NASA is still living on the investment made [during the Apollo
era], but cannot continue to do so if we are to maintain United States
leadership in space.” Several recent studies concur, concluding that our
technology base has eroded and technological research and development are
underfunded. The technology required for bold ventures beyond Earth's orbit has
not yet been developed, and until it is, human exploration of the inner solar
system will have to wait.
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Technologies explored by
Project Pathfinder.
Project
Pathfinder has been developed by NASA’s Office of Aeronautics and Space
Technology in conjunction with experts on the Lunar and Mars initiatives.
Pathfinder would provide the technologies to enable bold missions beyond
Earth’s orbit: technology for autonomous systems and robotics, for lunar and
planetary advanced propulsion systems, and for extraction of useful materials
from lunar or planetary sources. It also deals in a significant way with the
human ability to live and work in space, by developing technologies for
life-support systems and the human/machine interface. Until advanced technology
programs like Project Pathfinder are initiated, the exciting goals of human
exploration will always remain 10 to 20 years in the future.
Life
sciences research is also critical to any programs involving relatively long
periods of human habitation in space. Because the focus of our life sciences
research for the last several years has been on Space Shuttle flights, which
only last for five to ten days, there has been no immediate need for a program
to study the physiological problems associated with longer flights. Without an
understanding of the long-term effects of weightlessness on the human body, our
goal of human exploration of the solar system is severely constrained.
Before
astronauts are sent into space for long periods, research must be done to
understand the physiological effects of the microgravity and radiation
environments, to develop measures to counteract any adverse effects, and to
develop medical techniques to perform routine and emergency health care aboard
spacecraft.
Project
Pacer, developed by NASA’s Office of Space Science and Applications, is a
focused program designed to develop that understanding and provide the physiological
and medical foundation for extended spaceflight. This research would be conducted
in laboratories and on Space Shuttle missions in preparation for the critical
long-term experiments to be conducted on the Space Station.
Until
the Space Station is occupied, and actual long-duration testing is begun, we
will lack the knowledge necessary to design and conduct piloted interplanetary
flights or to inhabit lower-gravity surface bases. Although the research
conducted prior to the occupation of Space Station cannot provide definitive
answers to several key questions, it is an essential precursor to the research
and technology development on the Space Station.
LIFE SCEINCES RESEARCH
The
prospect of an extended human presence in space on the Space Station and tended
missions to the Moon or Mars requires a commitment to better understand and
respond to, biomedical, psychological, and human engineering challenges.
Although there is great confidence that we win eventually establish a presence
on other bodies in the solar system, there remains uncertainty in the medical
community about the implications of such journeys for human health, safety, and
productivity. A number of recent studies highlight concerns and identify areas
requiring additional research.
“Space
medicine is unique in the context of the other space sciences — primarily
because, in addition to questions of fundamental interest, there is a need to
address those issues that are more of a clinical or human health and safety nature
... if this country is committed to a future of humans in space, particularly
for long periods of time, it is essential that the vast number of uncertainties
about the effects of microgravity on humans and other living organisms be
recognized and vigorously addressed. Not to do so would be imprudent at best —
quite possibly, irresponsible.” A Strategy for Space Biology and Medical
Science, 1987
“Many
crucial issues in the three major areas of health, life support, and
operational capabilities remain to be resolved before the safety of humans
working in space over months and years can be assured. Certain aspects of
physiological adaption to microgravity may be life-threatening, especially over
the long-term … Areas such as medical care, radiation protection, environmental
maintenance, and human productivity are equally serious, but the research and
development activities associated with these areas have at least begun on a
modest scale. To neglect any of these areas could risky, and parallel research
activities commended.” Advanced Missions Humans in Space, 1987
“Of paramount practical importance are human safety
and performance. Long-duration flights on the Space Station will increase our
understanding of the effects of the space environment on people and other
living systems. Problems of bone demineralization and loss of muscle mass
persist, and effective empirical solutions are unlikely to be found soon … It
is imperative that basic research on this problem continue, both on the ground
and in space.” Pioneering the Space Frontier, 1986
Both technology
development and life sciences research are pacing elements in human
exploration.
The
four initiatives represent widely varying levels of complexity and commitment.
As part of the development and evaluation of the initiatives, an assessment was
performed to estimate their relative complexities and therefore their relative
impacts on the agency and its resources. The initiatives, and results from
related studies, were reviewed to identify the required technology,
transportation, on-orbit facilities, and precursor science. This assessment
yielded the elements comprising each initiative — the building blocks of that
initiative.
The
assessment sought to define the initiatives to a reasonable level of detail through
2010. At this time, the initiatives would be in different stages of
development. All Earth observing platforms would be in space with their
observing systems operating; they would be serviced periodically, and would
continue to transmit data to Earth for years. The final mission of the
Planetary initiative would be complete; this initiative is not defined past
2010. The Lunar outpost would be well established, with most surface elements
developed and delivered; it would receive continuing logistics support, but
would be somewhat self sustaining, and have considerable potential for growth
and for support of further exploration activities. In 2010, the nation's Mars
program would have just finished its human reconnaissance phase, and would be
prepared to embark on the establishment of an outpost.
To
provide a common starting point for each initiative, this analysis assumed the
currently planned NASA space program as a foundation. That is, each initiative
must be built from the foundation of a fleet of four Space Shuttles and a Phase
I Space Station; everything else that would have to be added to accomplish the
initiative, including additional Space Station modules, new transportation
elements, unscheduled precursor science missions, etc., was assumed to be part
of that initiative.
Some
of the elements of each initiative would be developed solely for that
initiative; many others could be common to other initiatives as well. An
example of the former is the lunar oxygen plant designed to extract oxygen from
the lunar soil. Although similar technologies might eventually be needed at a
Mars outpost, the element itself exists only in the Lunar initiative. An
example of an element which could be common to several programs is the space
transfer vehicle of the Earth initiative. Although it would lift geostationary
platforms from the Space Station to their final orbit, this vehicle could also
be used to deliver other cargo (unrelated to the Earth initiative) to
geosynchronous orbit, or it could be the basis of a lunar transfer vehicle.
Each initiative has elements which could be common to other programs, as well
as initiative specific elements.
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Table 1. Transportation Requirements
for the Initiatives
An
overview of the transportation elements required for the initiatives is shown
in Table 1. The Earth and Planetary initiatives make the most modest
demands on transportation, in terms of both essential new capabilities and
frequency of use. But each of the initiatives requires an Earth-to-orbit transportation
system comprised of more than just a Space Shuttle fleet.
A
heavy-lift launch vehicle is either enabling, or significantly enhancing, to
all the initiatives. A Shuttle-derived vehicle would have sufficient capacity
for the Earth and Planetary initiatives. It would also satisfy the requirements
of the Mars and Lunar initiatives through the 1990s, although shortly after the
turn of the century both would need a vehicle with a lift capacity of 150,000
to 200,000 pounds. This higher lift capacity is needed primarily to supply the
large amounts of propellant required for each initiative (about 2.2 million
pounds to low-Earth orbit for each Mars sprint mission; 200,000 pounds to
low-Earth orbit for each lunar trek).
SPACE STATION EVOLUTION
The
Phase 1 Space Station will be a permanently staffed “laboratory in space” by
1996. Other capabilities, such as an assembly station or a fueling depot, will
not be included in the initial phase, but could be accommodated later if a need
for those functions is clearly identified.
A
key question for the not-too-distant future is “How should the Space Station
evolve?” Since the Space Station is a means to pursue our goals, the answer
depends on what those goals are. It is important to understand what each
initiative demands of the Space Station. For example, the Planetary initiative
makes few demands on the Space Station; the Mars initiative makes substantial
demands.
NASA’s
Office of Space Station has set up a Strategic Plans and Programs Division
whose charter is to understand how the Space Station would be required to
evolve under a variety of scenarios for the future, and what provisions must be
made in the design of the Phase 1 Space Station to ensure that the evolution is
possible.
Space
Station evolution workshops, held in September 1985 and July 1986, laid the
foundation for understanding how to accommodate a variety of users whose
requirements may not be compatible. These workshops recognized, for example,
that a laboratory in space, featuring long-term access to the microgravity
environment, might not be compatible with an operational assembly and checkout
facility, as construction operations could disturb the scientific environment.
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Artist’s conception of the
Phase 1 Space Station.
Space
Station evolution planning will include an assessment of the implications of
each of the four initiatives. It is important to have specific scenarios, with
a level of technical definition behind them, to serve as a basis for these
assessments. It is also important that results from these assessments feed back
into the initiative scenarios. This iterative approach is required to establish
reasonable evolution scenarios and initiatives that are compatible with the
proposed evolution.
The
Lunar and Mars initiatives also have a critical need for the capability to
transport personnel to and from the Space Station. This need could be filled by
a personnel module added to the Shuttle, or by some other personnel carrier.
The additional crew members would perform on-orbit assembly of the cargo and
crew vehicles. Although there is currently no good estimate of the size of the
crew required to assemble and test a vehicle in orbit, it is likely that the
Lunar initiative, if it develops as projected in Phase III, would require more
than 30 people in low-Earth orbit by the year 2010. It builds to this peak
gradually, though, and the early assembly requirements (2000 to 2005) can be
phased in slowly.
All the initiatives have other needs as well. The
Planetary initiative's needs are limited to expendable stages, and possibly an
Orbital Maneuvering Vehicle for the recovery of a returned Mars sample. The
Earth initiative makes more substantial use of Earth-orbital transportation,
including a transfer vehicle to lift fully assembled observing platforms from
the Space Station to geosynchronous orbit, and sophisticated Orbital
Maneuvering Vehicles to aid in platform servicing. The Lunar and Mars
initiatives are more demanding. Both are likely to require Orbital Maneuvering
Vehicles to transport personnel from the Space Station to orbital assembly
sites. Most significant, both require substantial space transfer vehicles to
transport crews from low-Earth orbit to either the Moon or Mars. Although the
lunar transfer vehicle could be a derivative of a transfer vehicle to
geosynchronous orbit (or vice versa), at this time it appears that the Mars
transfer vehicle will demand a different design.
The
orbital facilities required for each initiative are shown in Table 2.
The Planetary initiative has limited requirements in this area; the other three
have extensive needs that begin with the Phase 1 Space Station. The Phase 1
Space Station includes polar platforms and attached payloads for the Earth
initiative; it serves as a technology and systems test bed for the Lunar
initiative; and it will be a crucial laboratory for life sciences research and
technology development for the Mars initiative.
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Table 2. Orbital Facilities Required
for the Initiatives
All
the initiatives require that the Space Station evolve additional capabilities,
but the needs of the Planetary initiative (a sample return module) and the
Earth initiative (servicing capability, operation of a space transfer vehicle)
are relatively modest. The Lunar initiative requires gradual evolution to
support the assembly, servicing, and checkout of lunar transfer vehicles. This
requires more people in orbit (and therefore more Space Station modules and
logistics traffic), spaceport facilities, and a propellant depot. The Mars
initiative also relies on those spaceport facilities and additional crew
accommodations, and although it will not occur quite as soon as in the Lunar
initiative, the assembly of the large Mars cargo and piloted vehicles will be a
significant task.
The Lunar initiative includes significant surface facilities such as habitation modules, laboratory modules, and an oxygen plant; the Mars initiative looks toward an eventual outpost (after 2015), but while similar surface facilities would be necessary at that time, they have not been included in the assessment to 2010. The Lunar and Mars initiatives both require landers, ascent vehicles, and rovers. These would most likely use some common technologies and subsystems, but they would not be identical.
The
initiatives also require investments in technology development, and investments
in institutional and human resources. This support early in the life of an
initiative is vital to its success. The level of investment required is
directly proportional to the magnitude and complexity of the initiative. The
Earth and Planetary initiatives would be expected to have relatively modest
needs; the Lunar and Mars initiatives would demand substantial technology
development programs, and significant increases in highly skilled personnel and
institutional facilities. The need for a dedicated, enthusiastic, and
technically competent workforce must not be minimized; the Lunar and Mars
initiatives would both require a significant increase in human resources.
The current level of definition of the initiatives, particularly the Lunar and Mars initiatives, is not adequate to reasonably estimate their costs. But while it was not appropriate to attempt to determine the absolute level of resources required by each, it was reasonable to estimate the relative levels through 2010. For each initiative, after the elements not included in current NASA plans were identified, the mass and size of each were estimated in order to determine the transportation requirements for that initiative. There was no attempt, at this early stage, to optimize the transportation system.
Figure
14 compares
the resources required by the four initiatives during the next five years. It
is important to understand the level of effort needed to support a new initiative
during this period, since the country will also be relying on the civilian
space program to return the Shuttle to flight, to reinvigorate its
transportation system, and to continue serious preparations for the Space
Station.
The
Lunar, Earth, and Planetary initiatives would take about the same level of
investment through 1992. The investment in the Lunar initiative would be primarily
in technology and in early transportation development; in the Earth initiative,
it would be largely in the development of the polar platforms, data handling
system, and transportation; in the Planetary initiative, it would be primarily
in technology, and in readying the Comet Rendezvous Asteroid Flyby
mission for a 1993 launch.
The
Mars initiative requires the largest commitment in the early years. This would
be primarily an investment in transportation elements and in life science
related additions to the Space Station. Transportation and Space Station use
have not been optimized, so some reduction might be possible. The message,
however, would not change: the country would have to make a major investment in
the next five years to land people on Mars in 2005.
The
complexity of both the Lunar and Mars initiatives in the year 2000 demands
technology developments early in the program. Thus, through 1992 the majority
of the Lunar initiative, and a significant portion of the Mars initiative,
would be comprised of those technology activities which lay the groundwork for
the initiative. Like early work in transportation, there is considerable
synergism in the early technology requirements of these two initiatives.
Figure
15 compares
the initiatives through 2010. The Lunar and Mars initiatives are nearly an
order of magnitude greater in programmatic scope than the Planetary and Earth
initiatives. The levels of investment in the Earth and Planetary initiatives
peak in the early-to-mid-1990s, and then decrease to levels which remain fairly
constant through the first decade of the next century. The Lunar initiative
does not require extraordinary resources through 1992, but the commitment
builds substantially in the mid1990s. It peaks in about 2000, at the time of
this initiative's first human landing, and stays high through 2010 as the
outpost is developed into a permanent base. The total level of effort through
2010 is large, and reflects the ambitious approach to the construction of the
lunar base. However, the nature of this initiative allows considerable
flexibility. For example, the outpost materials could be delivered to the surface
rapidly or at a more deliberate pace; certain capabilities of the outpost could
be emphasized and developed before others; or the transition from a temporarily
occupied outpost to a large permanently staffed base could be delayed. Any of
these options would significantly reduce the investment through 2010.
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Figure 14. Resources Required by
Initiatives through 1992
Figure 15. Resources Required by
Initiatives through 2010
Although
the Mars initiative offers the greatest amount of human and technological
drama, it also demands the greatest investment. The Mars initiative definition
included only those elements required for the three sprint missions, the last
in 2010, so the level of investment shown is artificially low between 2005 and 2010.
The magnitude of the initiative indicates a large commitment of resources, and
the timescale dictates that the investment peak in about 2000.
It
is possible to reduce the early investment to a level comparable to that of the
other three initiatives by allowing the first human landing to occur in 2010,
rather than in 2005. The 2005 landing was selected at the outset to achieve the
major milestone within two decades, but this analysis suggests that this ground
rule may not be appropriate for the Mars initiative.
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