Elon Musk made it pretty clear than anyone hoping to colonise the Red Planet has made a tactic agreement to be a blood sacrifice to SpaceX. Fine, no one said space travel was safe. But the survivors have a new danger to consider: Space brain. Space madness
In a study published in Nature's Scientific Reports, scientists at the University of California, Irvine bombarded rats and mice with ionised oxygen and titanium, the types of charged particles found in galactic cosmic rays that are mostly likely to pass right through the shielding on most spacecraft — the stuff astronauts on long-haul missions would expect to experience. Their results were less than heartening.
The mock-cosmic rays caused damage to neurons and brain inflammation which was still present six months after these rodents were zapped. In such a state, astronauts might experience poor decision-making and trouble performing tasks, as well as a variety of mood issues. Of particular note was the radiation's deleterious effect on a brain process called fear extinction — essentially our ability to forget prior stressors so we don't live in a constant state of anxiety.
Studies of this nature have been carried out before, with similarly alarming results. NASA-funded studies have demonstrated similar neurological damage in rodents, though this is the first to show how prolonged that damage is. Thought they'd appear to make good case studies, ISS astronauts don't undergo issues with galactic cosmic rays because the space station is still within Earth's protective magnetosphere.
Everyone knows a manned flight to Mars would be dangerous. The new concern is what sort of state future colonisers will be in once they land.