Human space adaptation helps us understand aging life on Earth evolved in the presence of gravity. For this reason, gravity plays a role in all life processes, and exposure to the microgravity environment of space affects living things significantly. Certain physiological changes that occur in space also occur with aging: for example, cardiovascular deconditioning, balance disorders, weakening bones and muscles, disturbed sleep, and depressed immune response. An important difference, however, is that these changes are reversible in astronauts.
Although humans have been traveling into space for three decades, and in increasing numbers of late, researchers have had limited opportunities thus far to carry out systematic biomedical research in space. The dedicated space biomedical research missions of Skylab in the early 1970s and recent Spacelab Life Sciences missions stand out as exceptions. An example is Neurolab, the joint mission with the National Institutes of Health, carried out in April of 1998. Future life sciences research missions, including research on the International Space Station, and continued collaboration with the National Institutes of Health will give researchers greater opportunities to solve the mysteries of space deconditioning and aging