But other viruses that linger inside cells for years or even decades are not so limited. In microgravity, astronaut immunity is depressed, perhaps quite literally. Our immune systems behave much like separate brains, with their own chemical and biological senses, controlling the body s basic responses to the environment. Bacteria seem to flourish in weightless conditions, which is easy to understand, given the nature of their medium. Water at their scale is like a very thick gel, and all their motions and chemical processes have to deal with this gel before they deal with the much less formidable effect of gravity.
Bacteria are masters at adapting in unexpected ways to new environments.
Biofilms can form complex slime cities, both bacterial armor and architecture, that protect bacteria from detergents and antibiotics. Aerosols of bodily fluids in space could protect viruses and bacteria for hours, or even days in some cases. In microgravity, some pathogenic bacteria show a troublesome increase in resistance to antibiotics and detergents. Such bacteria, like latent viruses, may be more likely to attack and spread when their hosts are under stress. And of course, space exploration produces unique kinds of stress in astronauts.