Sticking with Mars trip theme.

Key to the ambitious endeavor, however, is ensuring the astronauts' safety, which may be difficult, according to a NASA-funded study published yesterday (Oct. 10) in the journal Scientific Reports.
This could be an issue.

The new study, in rodents, shows that astronauts could suffer from a phenomenon called "space brain" during the long trip to Mars, as cosmic radiation bombards their bodies and damages their brain cells.

Researchers exposed the laboratory-bound rodents to a level of radiation similar to that expected on a six-month one-way trip to Mars. They found that the radiation caused significant long-term brain damage, including cognitive impairments and dementia, a result of brain inflammation and damage to the rodents' neurons.
Train all your life, risk that very life, all to get to Mars. And then damage one's mind enough that you don't remember it? Nature can be cruel.