If there's one thing worse than getting sick, it's getting sick millions of miles from home. Unfortunately for Earth's vanguard of Martian explorers, that very well could be what's in store.
NASA researchers have just completed the first study of its kind on how the human immune system deals with a long-term stay in microgravity.
Ref: Alterations in adaptive immunity persist during long-duration spaceflight. NPJ Microgravity (2015) | DOI: 10.1038/npjmgrav.2015.13