[The adaptive-compensatory reactions in adjusting to space flights].

In this paper an evolutionary approach is used to substantiate the steps of life evolution on Earth towards overcoming the gravitational forces with the formation of metabolic cycles controlling the energetic of anti-G processes. The step of an adaptation to hypogravity was similar to return of surface animals to an aquatic environment. The impossibility of coming back to land was the "price" of adaptation to the aquatic environment. This phenomenon was used by the author as a logical model of human adaptation to a weightless environment. The concept of adaptation is examined from two points of view: adaptation and compensation. The scheme contains 4 steps of adaptation to space mission environments: Step I-preadaptation (phase of primary reactions); Step II-compensation of body structures not being in line with the conditions of a novel environment; Step III-the formation of parameters of an organism corresponding to the norm of adaptation to weightlessness; Step IV-the return of cosmonauts to Earth under hypergravity conditions. In compliance with these steps we consider the tasks of supporting space missions to facilitate body readaptation after return to Earth, i.e., to decrease the "price" of adaptation.