Life Sciences: Space Science in the Twenty-First Century -- Imperatives for the Decades 1995 to 2015 (1988)

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INSTRUMENTATION AND TECHNOLOGY 134 8 Instrumentation and Technology INTRODUCTION The ultimate success of the research described in the preceding chapters will depend upon (1) the appropriate applications of existing technologies, (2) the development of new ones, (3) a refined understanding of the interactions between humans, computers, and machines, and (4) the optimal reduction, archiving, and retrieval of data. Many life sciences disciplines (and probably others as well) would benefit from a ''return capsule'' with capabilities similar to the Soviet "Progress" capsule. Such a craft would have the ability to deliver expendable systems and return samples, specimens, wastes, and experimental materials. For clarity, the task group addresses each of the five disciplines— exobiology, global biology, space biology, space medicine, and CELSS— separately. However, many of the needs, especially those of computation and robotics, are common to more than one discipline. 

INSTRUMENTATION AND TECHNOLOGY 135 EXOBIOLOGY General The requirements for special instrumentation and technologies for exobiological investigations cover a very wide spectrum, from unique ground- based laboratory facilities and techniques to dedicated space missions to other objects in the solar system. Specific Needs • Microchemical techniques for the identification of materials in individual microfossils. • Highly sensitive mass spectrometric techniques for the identification of compounds and isotopes. • RNA synthesizers, similar to those already available for the synthesis of DNA. • Laboratory simulators: Several kinds of simulators would be useful for trying to understand the course of chemical evolution. These range from devices to suspend one or more particles (to simulate interstellar grains), to large simulators to study the formation and evolution of organic compounds over long periods of time. • Collectors for cosmic dust particles: methods need to be developed for use in space that would provide for the nondestructive capture of interstellar and interplanetary particles. • Rover technology with special emphasis on optimizing interactions with remote human operators. • Technologies for the collection and subsequent handling of extraterrestrial samples. • Hubble Space Telescope (HST): This new tool could yield substantial information for exobiology. It could be used to inventory biogenic elements in external galaxies, to image Titan in the ultraviolet and visible range, to search for organic molecules in Titan's atmosphere in the ultraviolet, and to study tenuous atmospheres in the outer solar system. • Space Infrared Telescope Facility (SIRTF): This instrument could also provide an enormous amount of new data for the exobiologists, especially if its spectral and spatial resolutions could be improved over those currently being planned. SIRTF could be used to identify and quantify the molecular constituents of the 

INSTRUMENTATION AND TECHNOLOGY 136 jovian planets and their satellites and to study the composition of intersteller grains, comets, asteroids, and external galaxies. • Large Deployable Reflector (LDR): This instrument could give information in the far infrared and millimeter regions of the spectrum. Its utility would be for study of protostellar objects, novae and supernovae, and the interstellar medium. GLOBAL BIOLOGY General Remote sensing is essential for research in global biology. In order for the results from sensitive spectrometers and other sensors to be interpreted accurately, they must be standardized against ground-based measurements. Sensing capacities must be developed to determine the biome distribution and productivity over the entire surface of our planet. Passive reflectance spectrophotometry in the ultraviolet, visible, and infrared, can supply much of this information. Specific Needs • Spectrometers in the visible and near-infrared with high spectral and spatial resolution. • Color imagers with high spatial resolution. • Laser fluorescence sensors for use in aircraft and spacecraft. • A synthetic aperture radar device for spacecraft studies of surface water and plant structure. • "Close probes" or penetrators: Instruments designed to make specific global measurements at remote or otherwise inaccessible sites on Earth. • Polarization photometers. SPACE BIOLOGY General Experiments in space biology and in space medicine will be expensive; opportunities will be limited. They must be preceded by thorough evaluation of ground-based model studies, for example by the clinostat or by bed rest. When eventually performed at 

INSTRUMENTATION AND TECHNOLOGY 137 microgravity, these experiments will require one-g controls in order to be reliably interpreted. Whenever possible, humans should be the subjects for the experiments for reasons both of economy and relevance. Even so, holding facilities specifically designed for a few species of plants, animals, and microorganisms must be provided. Specific Needs Solution of the interrelated problems of phototropism and geotropism requires the development of sophisticated plant growth chambers similar to those of CELSS. A range of variables must be monitored and, in some instances, regulated. These include: light intensity; period and spectrum; oxygen, water, carbon dioxide, and ethylene concentrations; and evolution of trace gases, some of which are not yet identified. Similar gas monitors are required to monitor the air of cabins to detect leaks or outgassing. They are also invaluable as research tools—applied to breath, sweat, urine, and feces of animals and humans—to monitor physiological state and general health. Provision must be made for freezing or lyophilizing specimens as appropriate for return to Earth for definitive analysis. Facilities to house experimental animals, including primates, for long periods of time on spacecraft will also be necessary. These facilities should be designed so as to provide structural isolation from humans but to permit functional interactions when necessary for animal care and for experimental purposes. For many investigations, including growth of crystals of proteins and of nucleic acids, it will be necessary to conduct experiments in an environment with approximately 10-6 g and <1 Hz. Such a locus is theoretically achievable at the center of the currently conceived Space Station. However, with projected growth (and activity) on the station, changes in the center of mass could pose significant problems. For these reasons, consideration should be given to the design of free flyers to provide the required low-g environment. Sensorimotor experiments, especially as they focus on the complex integration of sensory information from the inner ear, the eyes, and proprioceptors throughout the body, require access to a centrifuge and a linear accelerator that will accommodate humans 

INSTRUMENTATION AND TECHNOLOGY 138 and primates. These experiments also require a range of electro-physiological equipment, including the placement of semipermanent electrodes in the brains of rodents and primates. In order to distinguish the effects of linear acceleration as it affects the otolith, and of rotation as it affects the semicircular canals, it is also essential to have a linear accelerator large enough to seat human subjects. Several additional types of variable-force centrifuges will be necessary to conduct life sciences research in space. The centrifuge to be used for vestibular / neurosensory research might serve as an operational device to prevent and treat spaceflight "deconditioning" in humans. For these, it may be necessary to consider a long-radius tether design. For centrifugation of smaller animals, a short-radius machine may suffice. In addition, consideration should be given to the design of a large-capacity, continuously running centrifuge at (or near) one-g to maintain plants and animals until they are chosen for weightlessness studies. Most importantly, a centrifuge designed to run inflight controls is essential for reliable interpretation of both plant and animal experiments. Prosaic as it may seem, the task group emphasizes the importance of binocular low-power and high-power microscopes for observing tissues and cells. These should have dark-field and fluorescence capability and be equipped with video for documentation and for direct transmission to sponsoring laboratories on Earth. Quality microscopy demands quality sample preparation— preservation, sectioning, and staining—as well as maintaining living cells. SPACE MEDICINE General Most of the proposed experiments, as well as monitoring of astronaut welfare, rely heavily on noninvasive and microchemical techniques. They also require an extensive data base to define "normalcy" at one-g and "normalcy" at zero-g. Consistent with her or his privacy, dignity, and function, every crew member should, as a condition of accepting the assignment, participate in establishing this data base. Their participation is much less expensive than maintaining an extensive colony of primates or than failing to detect the first signs of illness. 

INSTRUMENTATION AND TECHNOLOGY 139 The psychology of group interactions will contribute to the assignment of crew, design of living and work spaces, and scheduling of activities. The unique circumstances of extended spaceflight will also contribute to the study of behavior. Again, consistent with established guidelines of medical ethics, the documentation and monitoring of behavior should be anticipated. Innovations might include correlation of various physiological and metabolic measurements and correlation of these, in turn, with composite indices such as activity, frequency of talking, and voice inflections. Specific Needs Noninvasive imaging techniques are required for research in all areas and will be valuable for health care. Echocardiography has been used in Shuttle flights to assess cardiac chamber size and function. Future ultrasound developments will include improved resolution, incorporation of function into the anatomical picture, and perhaps even the ability to measure not only internal anatomy and flow, but also, indirectly, pressure. Ultrasound will be important in bone work and in muscle studies. Newer ultrasound techniques may be developed to image discrete muscle groups and correlate images with muscle tone and elasticity. Lightweight photon spectrometers can improve the scope of bone research. New methods that merit exploration include: electron spin resonance (possible after ingestion of bone-specific dyes containing free radicals) and piezoelectricity (of teeth). Computerized axial tomographic (CAT) scanning could have great utility in bone and muscle research if smaller, lightweight instruments are developed. The same is true for nuclear magnetic resonance (NMR) techniques, which have the additional virtue of being able to monitor biochemical changes in cells. These imaging techniques should be complemented by the development of several minimally invasive or noninvasive physical monitors and chemical techniques. Important measurements include temperature, heart rate, blood pressure, oxygen tension, pH, electrolytes, osmolality of perspiration, and muscle tone. The possibility of wearing a simple "smart band-aid" or wristwatch that could measure and even process some of these data from skin should be pursued. Microchemical analyses should be developed for urine, saliva, sweat, and small volumes (0.01 ml) of blood. Measurements should 

INSTRUMENTATION AND TECHNOLOGY 140 be made of standard metabolites, byproducts of drugs, various hormones, antibody titers, and enzymes. Various of these reactions can be performed "dry," that is, with reagent-impregnated papers and with extremely sensitive and specific antibody-coupled reagents. These physical and chemical procedures will serve onboard health care as well as primary research functions. Recent and projected advances in immunochemistry and cell culture should be utilized. The task group anticipates the need for a miniaturized laser- cytofluorograph for the analysis of lymphocytes and other cell types. Automated instrumentation incorporating monoclonal antibodies and antibiotic sensitivity should be developed for microbial identification. Several general monitoring systems are required as integral components of health maintenance and safety. Cabin air should be routinely monitored for particulates, aerosols, bacterial count, and various trace gases. Radiation, especially heavy ion particles, must be measured. A protected multipurpose area to be used to counter radiation and toxicological exposures, fires, and loss of cabin pressure and for quarantine of communicable disease should be designed. This combination of analyses and monitors is required both for research and for improvement of astronaut safety, health, and performance. These data must be integrated to help understand the whole person; the final monitor is behavior and performance. The task group recommends the development of objective and predictive monitors of behavior such as frequency and type of activity, and voice pattern analyses. CONTROLLED ECOLOGICAL LIFE SUPPORT SYSTEM (CELSS) General There is considerable overlap between the technology and instrumentation required for space-and ground-based research in CELSS, and that required for space biology and space medicine. Therefore, the task group focuses here on those facilities that need to be developed. 

INSTRUMENTATION AND TECHNOLOGY 141 Specific Needs Essential to the development of a Controlled Life Support System is a growth chamber for higher plants (a "phytotron" or "biotron"). The building of such a facility, with its control systems for lighting, gas sensing, and nutrient and water delivery in space, would be a major undertaking. Since it is unlikely that this system will also satisfy the needs of plant researchers interested in gravitational biology, additional plant growth chambers will need to be developed. The task group cannot yet specify a controlled ecological system that would be adequate to supply portions of the astronauts' food, water, and oxygen, and to recycle their wastes. Many ground-based studies must be initiated now and completed well in advance of even preliminary designs for a space vehicle that could recycle a significant portion of its water and organic compounds. As noted earlier, we cannot yet choose the most appropriate plants, algae, or yeast, nor make reliable estimates of the quantity and quality of their edible products. These plants and cultures of algae or of genetically engineered cells are continuously operating chemical factories and require automatic controls and sophisticated external monitors. These include: measurement of pH, conductivity, spectra (absorbance and fluorescence), dissolved molecules such as urea, glucose, and plant hormones, and evolved gases such as water vapor; oxygen, and ethylene. Human observation of higher plants may be the best monitor. An examination of individual cells or squashes for karyotype changes and chromosome staining patterns will be required to monitor mutations and transpositions, especially in artificially created cells. The optimal use of these cultures and higher plants requires not only a better insight into the photosynthetic organisms themselves, but also a refined understanding of human nutrition under flight conditions and of the food technology that will process and supplement the products of photosynthesis. Methods need to be developed for the harvesting, milling, mixing, and preparation of foodstuffs. Fluid handling technologies need to be developed for use in a weightless environment. This applies both to liquids (e.g., how to best deliver water to plants) and to gases (e.g., how to separate and store biologically produced oxygen and carbon dioxide). Control system methodology must be designed for CELSS that 

INSTRUMENTATION AND TECHNOLOGY 142 will maintain an essentially constant environment even though the elements of the system have different time constants for generation and uptake. Waste disposal and waste utilization techniques for the conversion of inedible plant products into recyclable materials need to be developed. COMPUTATION, INTEGRATION, AND ROBOTICS The experiments described, especially remote sensing for global biology, will generate up to 109 bits of data per day. It is imperative that the appropriate strategies for formats, data reduction, onboard computations, data transmission, and data archiving be determined well in advance. In general, precedents of other disciplines should be honored. Biological experiments and health maintenance pose several unique problems. Much of the work is interactive in that a subsequent step cannot be decided on until an initial result has been analyzed and discussed with an earth-based laboratory or clinic. In particular, microscope images or physiological monitors may have to be transmitted in real time, anticipating a prompt response. This may require interactive graphics with mutual manipulation of "drawn" objects. Organisms—humans included—are complex; the evaluation of experiments on them requires the integration of much information. Humans, ground-based, or as crew members, must interact with instruments and pieces of equipment that contain complex mechanical components and powerful computers executing complex algorithms. Although in principle this situation is hardly novel, the extreme conditions of space research and construction dictate a major investment now in robotics. It is inappropriate for this task group to address the political, emotional, or ethical aspects of manned spaceflight. Nevertheless, any rational analysis of man's role in space must include an analysis of robotics. The issue is not man versus machine. Inevitably, both are involved; this task group seeks to optimize their interactions. A simple mechanical hand can grasp with strength under extremes of temperature and radiation. The human eye and brain can recognize instantly an unanticipated signal hidden in a noisy image. How best to transmit tactile information from a distant "hand?" How to correlate these with video images? What response times can be tolerated—seconds or days—in the sensation or the command sequence? In 

INSTRUMENTATION AND TECHNOLOGY 143 addition, work is needed in the area of teleoperations—the creation of a real- time interaction by radio / TV link between the ground-based investigator and the on-board experiment or surrogate experimenter. This capability will allow experiment revision or modification in much the same fashion as on the Earth. The answers to these questions should have profound effects on the future of all the space sciences.