Abstract <p>At present, the mechanisms of human adaptation to the action of weightlessness, which humans, as a biological species, have encountered only recently, continue to be intensively studied. Understanding the mechanisms of human adaptation to weightlessness allows us to propose ways of modulating this process with preservation of useful adaptive reactions against the background of suppression of negative syndromes characteristic of space flight and inhibition of mechanisms preventing favorable functioning of physiological systems after returning to the conditions of gravity. One of the integral components of the system of countermeasure of the negative influence of weightlessness is artificial reproduction of the effects of gravity, i.e., imitation of the impact on the human body of the weight load characteristic of Earth’s conditions. The article considers the role of artificial reproduction of the effects of the weight load corresponding in value to the weight of the human body before the space flight. The article tests the hypothesis about the possibility of modulation of adaptation processes to weightlessness conditions by providing the necessary sensory inflow to the receptors of gravity-dependent physiological systems and its influence on the processes of re-adaptation to Earth conditions. The “weight” loading used during the flight was analyzed, as well as the data of pre-flight, flight, and post-flight tests on the performance of ten cosmonauts who performed long space flights with an average duration of 173 ± 33 days. It is shown that regular reproduction of the effects of weight load corresponding to the human body mass on Earth allows one to modulate the process of human adaptation to weightlessness.</p>