The efforts to send a manned mission to Mars are gearing up, but there is a new problem on the horizon. While the astronauts selected will have the honour of being the first humans to set foot on the Red Planet, they may also be some of the first to experience cognitive impairment from exposure to galactic cosmic rays.
This issue has been unearthed in a new study by scientists at UC Irvine, which found that the charged particles found in space, left over from past supernovas, can cause major damage to the central nervous system, resulting in impairment similar to that experienced by dementia sufferers.
The effects of this exposure takes several months to take hold, so has not been an issue for previous manned missions, but with the Mars mission set to take more than six months each way plus significant time spent on the Red Planet, the effects could be serious.
“This is not positive news for astronauts deployed on a two to three-year round trip to Mars,” said Charles Limoli, a professor of radiation oncology in UCI’s School of Medicine.
“Performance decrements, memory deficits, and loss of awareness and focus during spaceflight may affect mission-critical activities, and exposure to these particles may have long-term adverse consequences to cognition throughout life.”
The study, which is published today in the journal Science Advances, saw the scientists expose rats to charged particle irradiation at NASA’s Space Radiation Laboratory at the Brookhaven National Laboratory.
The particles, fully ionized oxygen and titanium, are very similar to the highly energetic charged particles found in the galactic cosmic rays astronauts are exposed to once they leave the Earth’s atmosphere, and so provide a good model for the likely effects.
The irradiated rats suffered from brain inflammation, disrupting the way their neurons transmitted signals and resulting in them performing increasingly poorly on behavioural tasks.
Although in rats, the scientists believe the study provides a fair representation of the effects cosmic rays will have on astronauts, making this a worrying set of findings for those involved in planning manned Mars missions.
While NASA is currently undertaking a study of long-term spaceflight on the International Space Station, the astronauts there are largely protected by the Earth’s magnetosphere.
This means they are unlikely to be affected by such particles, which is why the agency drafted Limoli and his team in to investigate this issue.
However, having demonstrated the problem, Limoli is now faced with the challenge of figuring out how to protect astronauts from these charged particles.
One option is to put protective shielding around the areas the astronauts spend most of their time, in particular their sleeping areas, but he is skeptical about how effective this would be, saying “there is really no escaping them”.
The best option is likely to be to develop a protective medicine, but is very early days and far more work needs to be done for this to be effective.
“We are working on pharmacologic strategies involving compounds that scavenge free radicals and protect neurotransmission,” said Limoli.
“But these remain to be optimized and are under development.”
With such support for the eventual colonisation of Mars, we will need to wait and hope for a solution.