Mars-bound astronauts could develop 'space brain' from exposure to galactic cosmic rays

As business moguls and politicians tout plans to put humans on Mars within our lifetimes, a new study warns that astronauts who experience prolonged exposure to space radiation could suffer from a long-term cognitive impairment dubbed "space brain."

U.S. President Barack Obama on Wednesday vowed to help send people to Mars within the next 15 years, pledging to work with private companies "to build new habitats that can sustain and transport astronauts on long-duration missions in deep space." SpaceX CEO Elon Musk, meanwhile, has been trickling out details of his even more ambitious plan to get to the Red Planet within a decade.

The technological and financial obstacles of such a mission are vast, but new research sheds light on the physical effects a lengthy space journey could take on the astronauts themselves.

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The further from Earth astronauts get, the more likely they are to be exposed to galactic cosmic rays, which are fully ionized, or charged, particles capable of penetrating spacecraft and human bodies.

'The remnants of ancient supernovae'

"They're coming from the remnants of ancient supernovae and they're coming from all directions," Dr. Charles Limoli, a professor of radiation oncology at the University of California Irvine's School of Medicine, told Quirks and Quarks host Bob McDonald of cosmic rays. Listen to the full interview on Saturday.

Those rays break down the structural complexity of neurons in the brain's pre-frontal cortex, which is associated complex cognitive behaviour like decision making. Limoni compared it to stripping the branches off a tree.

"It may impact the ability of astronauts to undertake multitasking, executive function, decision-making, or respond to unanticipated events," he said.

In earlier research, Limoli's team exposed rodents to space-like levels of radiation for six weeks and observed significant cognitive damage. The rodents performed badly on memory and learning tests, and showed elevated levels of anxiety.

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In their latest study, published last week in the journal Scientific Reports, the scientists delve into the long-term consequences. Mice and rats were exposed to ionized oxygen and titanium particles at the NASA Space Radiation Laboratory at Brookhaven National Laboratory in New York and then sent to Limoli's lab for follow-up observation.

Six months later, the rodents were still suffering from neural damage.

What's more, Limoli says the team's latest unpublished data shows the damage is still present one year later, which he called "a cause for concern."

While there's no evidence a trip to Mars would cause "something that you would recognize as full-blown Alzheimer's," it could affect the participants' memory and ability to adapt to changing situations and make spur-of-the-moment decisions — important stuff for an astronaut on a dangerous space mission.

"A slight impairment in their performance may be more consequential," he said.

Not a 'deal-breaker' for Mars

So is there any way to move past this obstacle and achieve the goal of reaching the Red Planet?

"I don't think this radiation exposure is by any means a deal-breaker," Limoli said.

It's all about brainstorming ways to protect the astronauts from exposure.  

There'll be a point in time when we want to engage in really deep space travel, and this continual exposure to the galactic cosmic rays is going to represent a problem we have to overcome.- Dr. Charles Limoli, Irvine School of Medicine 

"The only thing that stops these particles is mass — putting material and nuclei and atoms in between an astronaut and this bombardment from galactic cosmic rays,"  Limoli said. 

The cost of shielding an entire spacecraft would be astronomical and unpractical, he admitted, but it could be possible to a build radiation-safe zone within a ship.

Another possibility is that astronauts could wear helmets when they sleep as an added layer of protection.

There's also the potential to develop drugs to protect the brain's neurons from the radiation's effects.

But these, he says, are short-term solutions. 

"Let's think beyond Mars," he said. "In a few millennia, if the human race is still around, if we haven't done ourselves in, there'll be a point in time when we want to engage in really deep space travel, and this continual exposure to the galactic cosmic rays is going to represent a problem we have to overcome."