Of interest in this connection are the problems which may be encountered during and following long-term exposure to weightlessness. Although there is no evidence of adverse effects on operative behavior, the possibility of biological disturbances on a cellular or subcellular level, which may cause a deterioration of the somatic basis, has been repeatedly stressed. Whether effects of this sort will occur or whether the organism will be able to adapt is still an open question. Since motion sensitivity based on vestibular stimulation differs widely among individuals, the selection of astronauts may solve the problem of zero-g vestibular disturbance. Reports from the MA-8 (Sigma 7) and Vostok III and IV flights seem to support this assumption. Moreover, experiments are being made in the slow rotation room at the Naval School of Aviation Medicine to study the Coriolis effects which arise when "artificial gravity" is produced by angular acceleration. Since man can adapt to wave motion on shipboard within a few days, a similar process may be expected to occur in the case of long-term weightlessness ([ref.150]).
[chapter 5]
Molecular Biology and Bioinstrumentation
To support biological investigations in space and to accumulate baseline data needed for manned space flight, NASA has conducted a program in laboratory research and theory. A multidisciplinary approach has included such fields as ecology, physiology, organic and biological chemistry, engineering, electronics, and optics. Emphasis in this program has been placed on qualitative and theoretical rather than purely descriptive research, and the investigation of fundamental biological phenomena at all levels, from the molecular to the total life form.
MOLECULAR BIOLOGY
Research in molecular biology has included chemical, physical, biological, and theoretical investigations of prebiological conditions on Earth and, possibly, on other planets; studies of cellular inclusions; genetic material (DNA and RNA) and coding; as well as energy transfer in biological systems.
The understanding of prebiological conditions on Earth, and possible conditions on other planets, depends upon the nature of the complex chemical species which might be encountered. Scientists have shown that biologically important compounds, such as amino acids, can be generated by applying an electrical discharge, ultraviolet radiation, or heat to a gaseous mixture. Biologically interesting compounds can be removed from such a system by condensation or absorption; however, in the limited time and space available in such experiments, many compounds are not produced in sufficient quantity to be measured.
The National Biomedical Research Foundation (NBRF) and the National Bureau of Standards (NBS) are conducting an investigation on equilibria in multielement systems. The distribution of molecular species at equilibrium is independent of the way equilibrium was reached and is dependent only on pressure, temperature, and elemental composition. Many of the conditions which might have arisen naturally can be approximated by thermodynamic equilibrium. Compounds which can be formed at equilibrium need no special mechanism to explain their presence. However, special mechanisms have to be sought for those compounds which could not be so produced and which would have been required for the structure and nutrition of the first living organisms.
In the absence of precise knowledge of the composition of the primitive planetary atmospheres, equilibrium concentrations with a wide range of temperatures, pressures, and elemental compositions are being investigated by NBRF and NBS. These investigators have postulated that the maximum atmospheric pressure may have approached 100 atm if the primitive Earth was sufficiently hot and if an appreciable portion of the water on Earth's surface today was present on primitive Earth. (If the present oceans were to evaporate, the surface pressure would be approximately 300 atm.) Low pressures of 10-6 atm and temperatures between 500° and 1000° K are being used.
A large range of N, O, C, and H compositions are being investigated for interesting and plausible combinations of factors. In these calculations an IBM 7090 computer is being used to obtain data on a very large number of combinations of chemicals. Other chemical species will be added as the research continues. Some results of this study give an insight into the variety of biologically significant chemicals which might have existed during Earth's primitive prebiological condition or may now exist on the surfaces and in the atmospheres of other planets (refs. [ref.151]-[ref.153]). The general method described by White et al. ([ref.152]), minimizing the free energy of the system, was used. The solution was approached by an iterative process, starting with an initial guess of concentrations of the compounds. At each step, M+1 linear equations are solved where M is the number of elements in the system.