Life support systems and optimal isotope composition in cosmonaut habitatsfor longterm missions

Differences in the isotope content of the biogenous chemicals of cosmonaut habitats are given a theoretical consideration. Rationale is given to the h ypothesis according to which the biochemical and biophysical processes in p lants, animals, and humans must be impacted by the isotopes of all the biog enous chemicals in cosmonaut habitats. Organisms were found to persistently make preference of lighter fractions of stable isotopes from the biogenous chemicals. In most of the compounds the light fraction of stable isotopes constitutes the greater portion by mass. However, the optimal isotope compo sition of biogenous chemicals is still unknown and necessitates biochemical , toxicological, biological and other kinds of research. The functions of a life support system should also include production and maintenance of an o ptimal isotope composition for habitats, i.e. water, oxygen, food stuffs in order to improve metabolism in and performance of cosmonauts. (C) 1998 Pub lished by Elsevier Science Ltd. All rights reserved.