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III
Other Critical Technologies for the
Human Exploration Initiative
Ongoing development of certain specific technologies is essential to the
HEI and offers potentially high payoffs in capabilities and long-term cost
savings. The committee assumes that HEI technology development will
complement rather than displace the NASA program of basic research and
technology development in such areas as materials and structures, sensors,
air-breathing engines, and data processing.
THE NASA 90-DAY STUDY
The Technology Assessment section (Chapter 8) of the 90-lDay Study
lists seven technologies (regenerative life support systems, aerobraking,
advanced space engine, surface nuclear power, in-situ resource utilization,
radiation protection, and nuclear thermal rocket propulsion). It continues
with "other technology needs, briefly sketched" under titles like "humans
in space." Although the NASA Figure 8-1 envisions focused research that
does not continue after five years, ongoing advanced technology research
will clearly be characteristic of the HEI for many years.
The committee agrees that these technologies are important, but be-
lieves that strategies for development of technologies should take account
of the lead times required and incorporate priorities according to whether
the technologies are essential to the HEI, or serve to enhance capabili-
ties. For example, provision of radiation protection, life support, and crew
safety are survival imperatives for all human space-based modes, and must
be addressed as major architectural considerations. Research on artificial
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HUAL4N EXPLORATION OF SPACE
gravity should be added to this list. On the other hand, aerobraking, ~n-situ
resource utilization, and nuclear thermal rocket propulsion technologies
may offer significant advantages In certain mission scenarios, but are not
essential for human missions in general.
There are other specific new technologies, not in NASAs list of seven
critical technologies, that can profoundly simplify and enhance opera-
tions In every mission scenario. Into clear examples are (1) advanced
human/machine systems for tasks in space, in order to improve the ef-
ficiency of humans, and (2) far more capable information management
systems for mission decision making. While the 90-Day Study recognizes
advances in information systems and automation and robotics as being im-
portant to the success of the HEI, the emphasis should be on technologies
that go one step farther, to greatly advanced computer-aided mechanical
extensions of human performance, i.e., human/machine systems.
ARTIFICIAL GRAVITY
Artificial gravity was not included in the NASA list of critical tech-
nologies. With the current state of knowledge, a multiyear exposure to
weightlessness, even with on-board exercise and countermeasures and an
intermediate stay on the surface of Mars, presents unacceptable risks to
the crew. Adaptation to microgravity makes return to a gravity environ-
ment dangerous and renders human performance on the surface of Mars
problematical. The questions of whether artificial gravity will be required
and, if so, how it will be provided are critical. The nation has no strategy
for research to determine the need for or provide artificial gravity.
Several alternative approaches to addressing the problem can be con-
sidered. In one, an early commitment could be made to provide artificial
gravity in the transfer vehicle to Mars. This option is not included in the
90-Day Study, but has been reviewed by NASA in the past and found to
increase the mass of a Mars transit vehicle by no more than 20 percent,
under the most conservative assumptions.
Another alternative is to determine the requirements for artificial
gravity by testing humans in a variable-gravity research facility in LEO. Such
a facility should permit research on human physiological Reconditioning
and countermeasures, including different artificial gravity radii and rotation
rates, in order to determine the optimal combination of gravity levels and
exposure times. Because of time considerations in human Reconditioning
phenomena, an operational research period lasting two to six years must be
anticipated before definitive answers about artificial gravity can be expected.
Short of undertaking long-duration research on human performance
in space, any research strategy for minimizing human risk of irreversible
or incapacitating Reconditioning should make maximum use of ground and
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OTHER CRITICAL TECHNOLOGIES
19
space station facilities for relevant life science research. Ground bed-rest
studies and incremental duration exposure of subjects in a space station
must be integrated with animal research in orbit, including use of the
SSF on-board centrifuge. In parallel with these tests, the effectiveness of
several candidate countermeasures to Reconditioning should be evaluated
in controlled experiments. If the Reconditioning is unacceptable and the
simpler countermeasures are ineffective or onerous, full-scale space-based
artificial gravity evaluation and facility development become imperative.
Another alternative approach, which is less thorough than the use of a
variable-gravity research facility but which could be carried out in parallel
with a lunar base development, is an investigation of the effectiveness of
lunar gravity as a long-term countermeasure. This approach would provide
Reconditioning data at three levels: O. 1/6, and 1 g. It would not, however,
help with the question of gravity gradient or contribute to any of the
engineering issues regarding a spinning spacecraft for Mars transit.This
approach is the most limited and time consuming. It also carries with it
the risk of negative results that would require the eventual, but delayed,
artificial gravity investigations described above.
ADVANCED HUMAN/MACHINE SYSTEMS
Mechanical and computer-aided extensions of human (astronaut) man-
agers can provide enhanced efficiency in inspection, assembly, maintenance,
repair, and exploration tasks. The most powerful approaches to human ex-
ploration will integrate humans with machine systems to accomplish more
than either can do alone. These approaches can range from low-level,
hand-in-glove teleoperation, through higher-level object-motion commands,
to planned task commands by a distant astronaut. Application of the many
automation and robotic systems needed to integrate humans and machines
can range from some of the early systems developed for space station man-
agement and operations, to precursor nonhuman missions, to advanced
synergistic systems of humans and machines operating on another planet.
Advanced human/machine systems are not merely an enabling tech-
nology, but a requirement for practical HEI operations. Technical advances
can extend profoundly the human role as master of highly flexible human
surrogates, but obtaining such potential benefits will require more than
complex robotry and automation. NASA presentations based on the 90-
Day Study implicitly recognize this by grouping operations in functional
categories. Systems that integrate automation and robotics with humans
permeate the arenas of vehicle maneuvering; vehicle servicing in space;
in-space and surface assembly and construction; planetary rovers; surface
operations; extravehicular activity and exploration; sample acquisition, anal-
ysis, and preservation; and scientific probes and penetrators. Reduction of
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HUA~1N EXPLORATION OF SPACE
EVA time alone probably will lead to increased efficiency and will increase
safety.
Most of the technologies discussed above and in the NASA plan
require long lead times. In many cases the basic research has barely begun.
make the HEI possible, the research foundation will have to be laid in
the areas listed in the NASA report and in such fields as artificial gravity,
more capable information systems, and human/machine systems.
The time at which these technologies are successfully developed is
important to the pacing of the progression from the Moon to Mars.
Representative terms from entire chapter:
critical technologies
