Long-term exposure to radioactive cosmic rays in space would likely permanently damage human brains, according to new research.
As a result, space travelers could have trouble multi-tasking or making quick decisions.
"For an astronaut, this might translate to a reduced ability to problem-solve, react to unanticipated situations, etcetera," said Charles Limoli, a professor of radiation oncology in UC Irvine’s School of Medicine.
This news adds another obstacle for those seeking to send humans to Mars and beyond.
Space is full of highly energetic, charged particles left over from past supernova events. These can penetrate ships and even human bodies, resulting in damage to cells.
Neuroscientists at UCI wanted to know what effect these cosmic rays might have on the mind.
At the NASA Space Radiation Laboratory in Long Island, New York, a group of mice were exposed to charged particles similar to those in space for less than two minutes.
The mice returned to UCI where, six weeks later, they were given a series of memory and learning tests.
"They showed a loss of curiosity or a reduction of the tendency to explore novelty," said Charles Limoli.
Researchers found the exposed mice became confused more easily and were less curious about changes in their environment, as compared to to unexposed mice.
Furthermore, the exposed mice had inflamed brains and disrupted neural communication networks.
Limoli said it would likely take months for any similar changes to manifest in an astronaut's brain, but given that a round trip to Mars might take several years, this could be a problem over time.
However, he stressed, the effects would likely be subtle, and he doesn't think they'd stop astronauts from carrying out operations critical to their mission.
"So I don't think these are deal breakers for long-term deep space missions."
Here on Earth, we are shielded from cosmic radiation by our planet's naturally occurring powerful magnetic field. The International Space Station is also within this protective magnetosphere.
However, Mars is lacking such a strong protective shield so any future colonizers would need to find ways to protect themselves from cosmic rays.
"We're going to have to have some shielding and probably go underground to a certain extent," Limoli remarked.
This research is related of Limoli's work with brain cancer patients who are often exposed to various photon-based radiation treatments. Such treatments can also impact cognition.
Next, his team hopes to study the longer-term effects of space radiation on the brain, and he says they are researching drugs that might help prevent some of the damage from cosmic rays.