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Introduction
OVERVIEW
The life sciences have been and will continue to be an in-
tegral part of our space program. As anticipated in the legend
of Icarus, flight can expose us to anoxia and extremes of tem-
perature, and spaceflight adds microgravity and radiation. We
cannot adapt to these conditions or protect ourselves from their
effects without a sophisticated understanding of the underlying
physiological responses. On spaceflights lasting for months, recy-
cling wastes becomes economically attractive; on flights lasting for
years, controlled ecological life support systems are imperative.
Research into several fundamental problems in biology plant
growth, biomineralization, vestibular function, and development-
will also benefit from access to microgravity laboratories.
We are seeing the birth of a new science that combines the
global perspective of the earth sciences with the principles of
ecology. NASA has the expertise and the organization to be a
major contributor to a global study of the interactions of the
biota with the atmosphere, hydrosphere, and geosphere. A greater
understanding of our biosphere will have a profound unp act on our
international relations and on our economy.
Speculations on how life began have occupied some of the
1
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best minds for millennia. The task group believes this is now a
soluble scientific problem. NASA can take a lead in the integration
of planetary sciences, molecular biology, and prebiotic chemistry.
The result will be a new understanding of our own origin and
evolution, and a more reliable estimate of the possibility of life
outside our solar system. The intellectual impact of exobiology
and global biology will probably equal that of molecular biology.
The four disciplines treated in this report exobiology, global
biology, space biology, and space medicine—span an extremely
broad range of intellectual subject matter and technology. Their
parent disciplines- ecology, molecular biology, chemistry, astron-
omy, and medicine—are well established. But there have been so
few flight opportunities for studies in these fields, especially space
biology and medicine, that they have yet to develop into mature
space sciences. They are all young disciplines, still defining their
basic questions and strategies. They are united by the study of
life, and especially its evolution.
EXOBIOLOGY
Understanding the origin, early evolution, and distribution of
life is the focus of a major scientific effort in NASA. The early
environment of the Earth is being deciphered through the study
of biological and chemical fossils in 3- to ~billion-year-old rocks.
Within our own solar system there are strong indications of organic
reactions on the surfaces and in the atmospheres of several plan-
ets, on the satellite Titan, and in comets and asteroids. Organic
molecules, many of which are constituents of living organisms,
have been detected in meteorites as well as in interstellar space.
Exciting discoveries of molecules synthesized in the laboratory un-
der conditions presumed to exist on the primitive Earth have led
to theoretical pathways concerning the origin of life on Earth.
The current view, which ~ gradually being confirmed, is that
the chemicals of life abound in the universe and that the conditions
that gave rise to life on Earth may exist in other places. We do not
yet know the detain of this chemistry, nor do we know whether life
has actually arisen elsewhere in our own solar system or beyond.
We do not even know for certain whether planets exist outside of
our own solar system, although there is good reason to believe they
do. This is an area of research that ~ tractable to both laboratory
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experimentation and space exploration and involves a broad range
of interdisciplinary collaborations.
By 1995, the task group expects that our capabilities in the
field of exobiology will have expanded markedly. By then we
should be able to probe comets directly through chemical analysis
and to identify and quantify the organic molecules in these bodies
and their relationship to early planetary history. We should also
be in a position to determine with some confidence the presence (or
absence) of other planetary systems. We should be able to collect
cosmic dust particles in space for detailed physical and chemical
analysis, particularly for organic content. At the same time, we
should be able to extend the search for clues to the history of life to
other planets, particularly Mars, where only preliminary studies
were done by Viking, and to Titan, Europa, and perhaps other
satellites of other planets. Studies of these bodies should include
a search for evidence of life forms that once existed, but are no
longer present. By ,995, we should also have the ability to search
our galaxy by means of radiotelescopes for signs of intelligent
· · . -
c~v~ ,~zat~ons.
GLOBAL BIOLOGY/BIOSPHE1lIC SCIENCE
The ability to travel in space has revolutionized our perception
of the universe and our place within it. Humans can now view
their planet from afar and contemplate its entirety while at the
same time applying their scientific armamentarium to an array of
problems not approachable by any other means.
Earth Is essential to human existence; it is the only planet
known to harbor life. Our understanding of the evolutionary rela-
tionships between living organisms and the planet is limited and
based on local or regional data gathered over the years by ground-
based observations. Spacecraft provide the means of obtaining
a global perspective, that is, of looking at and measuring key
phenomena globally and continuously.
Fundamental to understanding the biosphere is deciphering
the interrelationships between biological processes and geochemi-
cal-geophysical processes. For example, study of biogeochemical
cycles through study of changes in atmospheric carbon dioxide
and periodic measurements of global biomass and productivity is
now both possible and timely. Monitoring biosphere-climate inter-
actions, measuring biogenic aerosols, monitoring surface changes
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induced by phenomena such as deforestation, desertification, and
agriculture, and measuring oceanic productivity are all activi-
ties that can be carried out from space. Interactions between
the biosphere and the atmosphere can also be measured from
space. These include the exchange of trace gases between the
biosphere and atmosphere, the effects of biomass burning, tropo-
spheric chemical cycling, and stratospheric contamination.
Earth-orbiting spacecraft offer the exciting prospect of mon-
itoring environmental conditions relevant to certain disease out-
breaks, such as malaria. By global monitoring of important vari-
ables such as seasonal rainfall and temperature, predictions of
outbreaks of mosquito populations can be made. Such studies will
allow much more effective modeling of global ecology. This, in
turn, will permit a recognition and understanding of threatening
trends.
The surface of the Earth, viewed in terms of temperature,
water content, sediments, and atmospheric composition, is com-
pletely different from that predicted as intermediate between
Venus and Mars. To understand our planet we must understand
the cumulative impact of 4 billion years of life.
CONTROLLED ECOLOGICAL LIFE SUPPORT SYSTEM
(CELSS)
Human exploration of our solar system will require missions of
long duration. These, in turn, require not only our understanding
of human tolerance and limitations, they also present extremely
complex technical and theoretical problems of providing the air,
water, and food for a livable environment. Eventually we will no
longer be able to carry from Earth sufficient supplies to support
extended space travel. The mere weight and volume of these
expendables will be beyond the carrying capacity of the spacecraft.
We will be forced to recycle ever more of these materiab. Air must
be cleaned and humidified or dehumidified, water purified and
reused, and food produced, consumed, and the wastes processed
and recycled. Virtually nothing can be discarded in the tightly
closed systems required for explorations of several years' duration.
These systems must be thoroughly evaluated in flight prior to
planning Tong missions.
As formidable as these engineering problems are, the biolog-
ical problems of such a life support system may prove even more
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s
difficult, especially if the human palate and psyche demand the
presence of higher plants. The effects of ~rucrogravity on plant re-
production, development, and growth especially when coupled
with those of artificial lighting are not understood. Success
in this endeavor demands imaginative cooperation between en-
gineers, chern~sts, nutritionists, and ecologists. Aside from the
utility of a Controlled Ecological Life Support System (CELSS)
as a life support aid, the concept of closing, at least partially,
an artifical ecosystem is of interest to the science of ecology and
may offer a research too! of considerable value for study of the
principles by which nature's ecosystems function.
SPACE BIOLOGY
Throughout its evolution, life on Earth has experienced only a
one-g environment. The influence of this omnipresent force is not
well understood, except that there is clearly a biological response
to gravity in the structure and functioning of living organisms.
The plant world has evolved gravity sensors; roots grow ~down"
and shoots ~up." Animals have gravity sensors in the inner ear.
Many fertilized eggs and developing embryos orient their cleavage
planes relative to the gravity vector. Access to a rn~crogravity
space station laboratory will facilitate research on the cellular and
molecular mechanisms involved in sensing forces as low as 0.001-g
and subsequently transducing this signal to a neural or hormonal
signal. A major challenge-to our understanding and mastery of
these biological responses is to propagate selected species of higher
plants and mammals through several generations at microgravity.
As was amply demonstrated by Pasteur, as well as countless
successors, investigations in medicine and in agriculture contribute
to and benefit from basic research. Understanding the responses
of humans and of plants to m~crogravity has enormous practical
significance for manned spaceflight. The use of m~crogravity to
eliminate microconvection in crystal growth, in electrophoresis,
and in biochemical reactions should continue to be evaluated for
both research and commercial application. Conversely, the urgent
need to moderate the debilitating effects of bone and muscle wast-
ing may lead to fundamentally new insights into biomineraliza-
tion and controls of gene transcription and translation. Although
serendipity is hardly the basis of a research strategy, we emphasize
the value to science in general and to biology in particular of
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creating a research environment in which a creative scientist can
observe unanticipated phenomena. These questions then become
the stud of logical analysis and formal reports.
HUMAN BIOLOGY AND SPACE MEDICINE
Our space program should develop the capability for manned
space missions of several years. So few data are available that
any projection is tentative. The physiological effects of short-
duration spaceflight will probably be tolerated or compensated
for, if not well understood and solved, by the middle of the Space
Station era (approximately 2005~. However, the long-term effects
of microgravity, or even the reduced gravity of the Moon, on
bone and muscle metabolism and on cardiovascular function will
probably remain poorly understood.
Crew members are protected from ion radiation by the Earth's
magnetic field while in the low-inclination, low-altitude orbits of
the Shuttle and the Space Station. However, they would be ex-
posed to significant heavy ion radiation during interplanetary m~s-
sions or while inhabiting a lunar or martian base. This exposure
could have disastrous effects on the central nervous system, be-
cause heavy ion radiation has recently been shown to inflict "single
hit" damage, even death, on nondividing cells.
The more general problem of the ability of human beings to
thrive in a closed, stressful environment assumes novel impor-
tance and exigency with extended spaceflights. In addition to the
problems of weightlessness and heavy ion radiation, the crew may
have to deal with increased microbial density in the cabin air, or-
ganic and inorganic toxins (outgassing products), nutritional lim-
itations, and the problems of health care delivery in space. These
physical stresses will exacerbate the sever_ emotional stresses as-
sociated with working and living in confined quarters. Many of
these problems have no terrestrial analog and must be understood
in much greater depth before we can permit a manned mission to
Mars.
Some of the research in space biology and medicine is con-
cerned with the health and welfare of the astronauts. Other com-
ponents are of basic scientific interest and deal with fundamental
questions concerning the role of gravity in life processes. The task
group believes that these two objectives complement one another.
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D!~LlDM1 :NTATION
The following chapters discuss the status and goad of these
five areas of research—exobiology, global biology, controlled ex-
ological life support systems, space biology, and space medicine.
Chapter 8 discusses the instrumentation and technologies required
to achieve these goals. The task group emphasizes that research
on tiering organisms, including humans, imposes constraints not
encountered in the other space sciences. On the other hand, many
of the instruments, as well as the strategies, of the global biologists
are common to the earth scientists. Similarly, the section treat-
ing exobiology contains numerous cross-references to the field of
planetary exploration.
Representative terms from entire chapter:
space biology
