SPACE SCIENCE BOARD WG-5/9 National Academy of Sciences _ Friday 29 June 1962 SPACE SCIENCE SUMMER STUDY Working Group on Fundamental Biology and Exobiology A. Extraterrestrial life 1. Earth studies on origin of life (a) Systematic investigation of the effects of electron microbeam and ion beam irradiation on the viability of bacterial spores, certain micro-organisms, and induced mutations. Since it is now possible by means of low-temperature electron microscopy to simulate many of the conditions encountered in Allen belt regions, these studies on the viability of spores and certain micro-organisms may prove to be of special significance (e.g. in connection with the "Panspermia" hypothesis). With improved instrumental and prepara tion techniques the electron microscope can now be used as a powerful tool both for the controlled production and direct observation of radiation damage in preselected macromolecular regions of . ydrated biological systems. 2. Radiation aspects (a) Exobiological aspects of radiation. The radiation environment, including UV, of ostensible exobiota should be characterized and the bearing of space radiations on the plausibility of panspermia investigated. Experiments should be undertaken regarding the capability of standard preparations of microbiota to survive the space environment, both without shielding and under various | shielding conditions. Studies on the survival of terrestrial microorganisms trapped in hard deposits are also relevant. Simulated environmental studies should include the radiation environment. Consideration should be given to the use of radiation in combination with other methods for sterilization of equipment to be sent into space, in the hope of finding procedures less injurious to components than is heating alone, The general subject of exobiology is regarded by all members 3. -2- of the subcommittee as being of paramount importance among all biological programs in the space sciences, Radiation aspects of this subject are listed below the foregoing two priorities only because of the specialized character of radiation in relation to exobiology. Theoretical approaches In all of these investigations it should be borne in mind that the detection of life on Mars would be only the first step. Equally impor- tant is its characterization from a chemical and biological point of view. We want to know whether Martian life--if such exists--originated independently from terrestrial life. This knowledge can be obtained only from detaiied studies. If Martian organisms are fundamentally similar to.our own, the possidility of their common origin with terres- trial organisms, and of transfer of living matter from one planet to another, will have to be considered. Terrestrial studies related to exobiology should be supported, These include work on organic syntheses under simulated primicive earth conditions and investigation of organisms living under extreme conditions of temperature, pressure, humidity, etc. Many of the approaches proposed by other groups appear to be distinctly earth-centered. We recommend (a) a characterization, on the basis of our knowledge of ‘Mars, of a possible organism on that planet, and (b) theoretical consideration of possible kinds of "life" other than that known on earth, Expectations for specific regions in space (a) Moon. The moon's surface is not considered to be habitable, but the possibility that life of some kind occurs beneath the surface should be considered, (b) Venus. Although apparently inhospitable to life because of its high surface temperature, Venus should not be abandoned as a possible biological objective until definitive evidence is obtained regarding conditions on this planet. The possibility that life exists in the cloud layer should be considered, even if the surface is uninhabitable. (c) Mars. Mars is the most important arena for exobiologicai studies, since evidence already at hand suggests that the planet is the abode of life. Despite the extreme dryness of the Martian environment, we believe that life as we know it--i.e., life based on nucleic acis and proteins--can exist there. ~ an ae J™ 5. ~3~ (d) Interplanetary space, Tae biological exploration of interplane- tary space should be a major NASA program. Attempts should be made to collect micrometeorites under conditions which will preserve any living matter they may contain. Biological studies of such material would provide a test of the panspermia hypothesis. In addition, systematic attempts to obtain carbonaceous chondrites by tracking and by purchase from museums should be supported. Detectors to be sent into space (a) From a distance. Spectroscopic studies in the IR and UV from bat Toons, observatories, and flybys. Listening for radio signals —— 7. from outer space, (b) From landing spacecraft (1) Organic chemical and atmospheric analysis, with special regard. to biologically important substances such as water, oxygen, carbon dioxide, ammonia, methane, and hydrogen sulfide. Water of hydration in soil should not be neglected. Other ecological parameters such as temperature, pressure, UV flux, etc. are also biologically important and should have high priority. (2) Direct life-detection experiments Metabolic methods--e.g., as proposed in the Gulliver Biochemical investigations--e.g., detection of enzymes, as proposed in the rnultivator. Microscopy TV observations Microphone peta — Sample retrieval In order to obtain all the information we require, it may be necessary to retrieve samples of Martian soil for study in terrestrial laboratories. Many of us believe that this should be recognized as the ultimate objective of éexobiological missions, Sample retrieval may well require a manned expedition and will involve the most advanced engineering and life-support systems, One-way expeditions of colonists to Mars were discussed.. The colonists could study Martian life in situ and transmit the information back to earth. No recommendation on this point. Biochemical detectors Use of metabolic criteria to detect living organisms. Gulliver, as we understand, is designed to pick up heterotrophs, place them in -4- appropriate labelled. substrate, and detect labelled CO, which may be released. It seemed to us that the alternative of designing equipment to detect possible autotrophs mizht be considered, The bulk of the biomass on earth consists of autotrophs; the same might be true of another living system, Thinking of photosynthetic forms, collected samples might be presented with labelled CO, , and search be made for fixed COj. This might have the advantages of (a) a greater probability of finding organisms, (b) less dependence on the nature of the substrate and (c) the possibility of carrying a dark control on the experiment. Optical Detectors (a) Spectroscopic examination of light reflected from a planet. Reflection absorption spectra of the surface of a planet might be used to detect. possible biological pigments. The use of narrow band lasers for this purpose was suggested. os (b) Direct investigation of the chemistry, molecular and submolecular organization of extraterrestrial matter in the solar system (interplanetary dust, meteorites, interstellar matter (solid particles, submicroscopic grains of ca. 10 to 1000 A.U., including gas hydrates, ate.) as revealed by appropriate electron- optical and related analytical techniques at low temperatures and ultra-high vacuum, Electron microscopy and related electron- optical techniques are of unique operational value as basic tools for space (biology) investigations by virtue of: (1) The requisite conditions for electron microscopy: high vacuum, electron beam and ion irradiation, thin speciments, and recently introduced low-temperature electron microscopy and electron diffraction, are very similar to conditions encountered in outer space. (2) The special techniques that have already been developed for electron microscopy are readily applicable to examination of extraterrestrial matter. Thus, the use of thin graphite or single-crystal stable coherent films, replication, shadow-casting, etc., are suitable for this purpose. For example: By coating satellites and space probes with these thin films, and then stripping them off for direct examination by electron microscopy, it should be possible to obtain adequate samples from space, Lunar and planetary probes, It should be pointed out that most of this material (c) (d) -5- would be well below the resolving power of light- and x-ray microscopes, and that electron-optical techniques would permit us to examine the structure and chemistry of these specimens (i.e. by electron microscopy, electron diffraction, electron microprobe analysis, etc.) in a way that can not be achieved by any other known technique. With present adyances in the generation of stable superconducting electromagnetic fields, it is conceivable that the contemplated design of new types of high-resolution "Cryo-electron micro- scopes" operating at Liquid helium temperatures and using "in situ" examination of lunar and planetary matter by electron-optical techniques. In view of the available high-vacuum and low-temperature conditions already prevalent in outer space such a cryo-electron microscope could be miniaturized. By being of smaller size and invested with a far greater resolution, of the order of 200 to 1000 x, than a light microscope, as well as the fact that the magnified images can be directly transmitted by modified television techniques, euch a cryo-electron microscope would permit a far greater range of applicatiions, and thus supplement the present contemplated light microscope systems. Successful application and development of these techniques requires special training and bio~instrumentation facilities, fit is therefore necessary, that after working out the optimum conditions for application of these electron-optical techniques to existing svace vehicles, thorough training of specialized technicians in the different NASA Space Research Centers be carried out. In view of the key operational significance of electron microscopy for future developments in bicchemistry, biophysics, and the bio- medical sciences in general, intensive development and research work is currently under way in specially organized centers in Russia, England, France, Germany, Holland, Japan, etc. Most of these electron microscopy centers are equipped and supported on an unusually large scale and on a long-term basis which re- flects distinct awareness of the vast scientific and technologi- cal potential of this field and related electron-optical disciplines, B. Radiation 1. Thorough characterization of space radiation by appropriate physical measurements. This characterization should include not only the energy distribution and flux of the various particles and other radiations, but also the temporal and spatical changes during solar flares. This knowledge is basic to all of the biological problems involving radiation in space. L£. opportunities-should_arise, the use of tissue-equivalent dosimeters is advocated as a stop-gap measure to secure a preliminary guide to problems of shielding, but this technique does not provide the informa- tion ultimately required, and is not regarded as having an independently high priority. Theoretical radiation biology. Our accumulated knowledge in radiation biology and recent advances in molecular and cellular biology, together with an increased understanding of the in vitro action of radiation on biological macromolecules, suggest that it is time to attempt a theoret~ ical analysis of radiation action on micro-organisms, animal and plant cells and possibly also on multicellular organisms. It is specifically suggested that several groups be set up in universi- ties or National Laboratories to develop theories to explain and/or predict radiobiological responses at the molecular, cellular and organismal level. A conference should be held at least annually among the participants to discuss results, and proceedings should be published. It is estimated that about $300,000 annually would support the cost of the conference as well as the research in such a program. Interagency cooperation may be desirable. Heavy Particle Experiments. Serious doubts were expressed in the sub- committee of the practicability of studying the biological effects of heavy primaries (Z greater than 2) in the space environment. The in- formation provided the committee on the flux of these particles suggest that it is generally too small to permit reliable, interpretable biolo- gical experiments within the practicable flight times of recoverable capsules. Simulation by means of available facilities such as HILAC and other particle beams was regarded as a useful approach, especially when combined with theoretical studies on the role of LET in biological radiation effects. Radiation Studies. If experimmts-on—the-RBE-efthe-radiations avail- able_in-space—are—contemplated, Fhe advantages of using certain plant materials should be considered. Advantages of high sensitivity, and relative ease in the scoring of somatic mutations by proper choice of experimental material. Chemical protection against radiation. The question of chemical pro- tection against radiation was discussed. It was recognized that the known protection agents are much less effective against radiations of high LET, as expected in space, than against low LET radiations. The committee concluded that this approach would have a high priority only if a new idea is proposed and that it is a subject that may be profit- ably considered in a theoretical study of radiation biology. C. Weightlessness 1. Sensing aspects (a) Low gravity environments. "Weightlessness" or free-fall conditions are unique to space environments. Sensory deprivation in animals of the following inputs needs to be examined: vestibular and statocyst, kinesthetic, cardiovascular and microcirculatory. Threshold differences may be specific for different organisms. (a) For the circulatory categories fluid distribution, particularly in venous return in mam- mals, may well be altered in the low-gravity environment. (b) Much is known regarding crustaceans, fish and marmais which have been deprived of their equilibrium receptors but it is not possible surgically to remove all gravity input. (c) Long-term experience jn the low-gravity state may lead to unique behavioral changes, particularly in mammals; short- term exposure may be less significant. (b) Statolith response, function, and development as affected by gravity was proposed. . Ranging from the "'labyrinth!' inner_ear.., | . of the mammal to the unknown statolith“of the plant, they Fev evel Dente, appear well suited to satellite experiments, provided that adequate telemetering of elicited responses and modifications can be obtained. In view of the reported balance disturbances in astronauts, experiments of the above type might indicate correlations on the effects of sub-g on the CNS. The nature and biophysics of the plant sensors