As commercial spaceflight becomes readily available, more and more people will have access to space. In decades past, only a few, elite pilots with specialized training could brave the harsh space environment. Now, anyone with enough money can hop on a rocket and fly into outer space.
With space travel becoming more accessible, scientists want to understand the long-term effects of simply being in outer space, especially with plans to colonize Mars in the near future. Researchers at the University of California, San Francisco, set out to answer this question.
Once outside of Earth’s magnetosphere (the region around the Earth dominated by the planet’s magnetic field), living things start to experience galactic cosmic radiation or GCR. GCR is made up of high-energy nuclei of stable elements. It is estimated that astronauts will experience 10x more GCR exposure on deep space missions than they would aboard the International Space Station.
There are very few humans that have been exposed to high levels of GCR, so these researchers used mice as a model. They modeled GCR in the lab by using a GCR simulation (produced and approved by NASA), then observed the cognitive and behavioral changes that occurred in the mice.
What they found proved interesting: there was a difference in cognitive defects between the male and female mice that were tested. Male mice had defects in spatial learning after being exposed to GCR, whereas female mice experienced little to no defects.
They also discovered a link between microglia and lasting defects in spatial learning. Microglial cells are found in the brain and spinal cord and make up about 10-15% of calls in the brain. GCR-induced learning deficiencies corresponded with microglia activation. Researchers found that when they depleted these microglia cells quickly after exposure to GCR, the spatial learning deficits of the male mice decreased. The depletion of the microglia was temporary, and after 15 days of treatment, microglia in the mice brains were able to return to normal levels.
Finally, researchers were able to identify some biological markers that correlated to the increase and decrease of cognitive functions in the male mice. Blood monocyte levels taken after one week of GCR exposure can predict the long-term spatial learning effects seen in male mice (5 months later). This has more significant implications for human space travel, where astronauts have limited personnel and monitor their vitals. Predicting cognitive defects early on will allow astronauts to take preventative measures before it’s too late.
Of course, these findings have only been shown in mice and need to be verified in human bodies before we start sending astronauts into deep space for long periods. It’s essential to do this research now— on the ground— to identify problems and solutions because the future of space travel is already upon us. We need to be prepared to meet it.
Source: Science Advances