Brain damage. Memory deterioration. Intelligence loss. This could be your brain on a trip to Mars.
It’s all thanks to the onslaught of galactic cosmic rays, the remnants of supernova explosions. These highly charged particles travel near the speed of light and can zoom through the hull of a spacecraft and human skin without a problem. Even though astronauts aren’t exposed to the rays at levels high enough to kill them, consistent bombardment with low levels of radiation can cause enough brain damage to impair their cognitive function. Astronauts would find themselves suddenly forgetful or unable to focus on a problem. Which, in the context of a complex and difficult space mission, has the potential to be deadly in its own way.
The finding, published in the open-source journal Science Advances this month, could throw a wrench in the many ambitious missions aimed at sending humans to Earth’s nearest neighboring planet: the controversial “one-way trip” proposed by Dutch nonprofit Mars One and NASA’s “Journey to Mars” program.
“The exquisite susceptibility of neuronal architecture” — in other words, brain structure — “to the effects of charged particles reported here has important implications for human exploration in space,” the authors wrote.
The first part of the study took place at the NASA Space Radiation Laboratory in New York, where the mice were exposed to the kind of radiation that astronauts experience in space. Once back in their own labs, the researchers then ran the mice through a series of cognitive tests to see how they responded to new situations.
The results were not encouraging. The exposed mice were much less able to cope with new experiences or differentiate between new and familiar objects, suggesting that the rays had damaged the parts of their brains that deal with memory and learning. When they took a look at the mice’s brains, they found that branches of cells in their brain had weakened and become less dense — a sign that those cells were less able to transmit signals.
Possible brain impairment is hardly the only health issue astronauts face. NASA is still working out ways to combat the effects of low gravity, which causes muscles to weaken and bones to decay. Not to mention the inevitable impact of sleeplessness, cramped quarters and freeze-dried food.
But a decline in brain function is especially problematic for anyone traveling to Mars, since the 100 million or so miles a message must travel to reach Earth causes a 20-minute delay in communication. Astronauts need to be able to figure things out quickly and on their own, the researchers argue — they can’t afford to suddenly forget how to deal with new experiences, as the mice did.
This problem is hard to handle, too, because any attempt at shielding the spacecraft from cosmic rays would make it bulkier and heavier, which would in turn require more funds and fuel. Instead, the study’s authors argue, NASA needs to figure out ways to counteract the effects of exposure. For example, a drug treatment that reverses radiation’s effects, co-author Charles Limoli, a neuroscientist at the University of California at Irvine, suggested to the Los Angeles Times.
But aerospace engineer Robert Zubrin, president of the Mars Society and an adviser to Mars One, says that the study’s findings have been blown way out of proportion. Rather than administer small amounts of radiation slowly over the course of many months, the researchers in the mouse study bombarded their subjects with 30 months’ worth of radiation in the course of about 30 seconds.
And although Limoli compared the mice’s exposure level to what an astronaut might experience during a 10- to 30-day mission when speaking with Pacific Standard, Zubrin said that the cumulative dose the mice received is 50 percent above what Mars astronauts would endure during a 2½-year mission.
“The irradiation doses inflicted on the researchers’ unfortunate subjects has no relationship to what would be experienced by astronauts on their way to Mars,” he wrote on the Mars Society Web site, adding “galactic cosmic radiation is not a show stopper for human Mars exploration, and should not be used as an excuse for delay.”
To be fair, Limoli isn’t calling his finding a “show stopper” either, he told Science magazine. It’s just “something NASA needs to consider,” he said.
More from Morning Mix: