EXPLORATION CLASS MISSIONS AND RETURN: EFFECTS ON THE IMMUNE SYSTEM
Immune responses have been shown to be altered when humans, animals and cell cultures are exposed to space flight conditions. It is clear that, although there have been some issues regarding infection on short-term space flights, alterations in the immune system have not been a “show-stopper” for space flight missions to date. However, as very long-term multi-year exploration class missions are contemplated, the potential for space flight-induced alterations of the immune system to have major impact on crew health and success of the mission increases. The increased concern is due to exposure to new conditions such as novel forms of radiation, and the isolation of the crew from the ability to obtain rapid relief and rescue due to health problems. If, during space flight, immune capacity is diminished while bacterial growth and virulence is enhanced, and antibody efficacy is altered, a difficult situation could arise. If an ineffective antibiotic is transported for use by the crew, there will be no replacement readily available during an exploration class mission. Additionally, radiation exposure combined with a suppressed immune system could facilitate tumor development after return to earth. In order to protect crews and assure the success of exploration class missions, studies must be undertaken in space, as well as on earth using ground-based analog models, to fully establish the risk and to develop countermeasures to prevent or minimized unwanted outcomes.