A study published in PLOS One on December 31 suggests that there may be unforeseen long term effects on spacefarers’ health. Long term exposure to heavily charged Galactic Cosmic Radiation (GCR) could increase the chances of incurring Alzheimers.
The study, which was conducted at the University of Rochester and Harvard Medical School with funding from NASA’s Space Radiobiology Research Program, exposed mice to doses of high energy, high charge (HZE) particles akin to those found in GCR. The mice received a dose of 100 cGy, equivalent to the total dose astronauts might experience on a trip to Mars. After six months, the mice experienced cognitive impairment and presented with plaques that have been correlated to Alzheimer’s disease.
It is very difficult to protect against powerful GCR radiation. “One would have to essentially wrap a spacecraft in a 6-foot (2 meters) block of lead or concrete,” explained corresponding author M. Kerry O’Banion, something that would be clearly prohibitive for mass-constrained launches. Unlike solar radiation, GCR is emitted isotropically throughout all points in space, making avoiding such radiation nearly impossible.
Unlike astronauts, the mice received their radiation dose all at once instead of gradually over time and were irradiated with only the heaviest ion - iron – rather than a range of ions that are present in GCR. The mice were also preselected for being genetically disposed to contract Alzheimer’s. It is not known how these factors could affect the results, but it is likely that this study represents a worst case scenario for the stated conditions. “I would add that there are at least three other laboratories pursuing similar studies,” said O’Banion, so some of these questions may be answered soon.
Although the radiation hazards of space travel have been known for sometime, this is the first indication of long term effects beyond typical radiation sickness. More such effects are likely to emerge as humans spend longer periods of time in space. One such discovery was made in 2012 when it was discovered that some male astronauts’ vision became apparently permanently impacted following cumulative long duration deployments on the International Space Station and Space Shuttle.