Mars-bound astronauts face chronic dementia risk from galactic cosmic ray exposure

October 10, 2016, University of California, Irvine
'The space environment poses unique hazards to astronauts,' says study leader Charles Limoli, UCI professor of radiation oncology. 'Exposure to these [highly energetic charged] particles can lead to a range of potential central nervous system complications that can occur during and persist long after actual space travel.' Credit: Steve Zylius / UCI

Will astronauts traveling to Mars remember much of it? That's the question concerning University of California, Irvine scientists probing a phenomenon called "space brain."

UCI's Charles Limoli and colleagues found that exposure to highly energetic charged particles - much like those found in the that will bombard astronauts during extended spaceflights - causes significant long-term brain damage in test rodents, resulting in cognitive impairments and dementia.

Their study appears today in Nature's Scientific Reports. It follows one last year showing somewhat shorter-term brain effects of galactic cosmic rays. The current findings, Limoli said, raise much greater alarm.

"This is not positive news for astronauts deployed on a two-to-three-year round trip to Mars," said the professor of radiation oncology in UCI's School of Medicine. "The space environment poses unique hazards to astronauts. Exposure to these particles can lead to a range of potential central nervous system complications that can occur during and persist long after actual space travel - such as various performance decrements, memory deficits, anxiety, depression and impaired decision-making. Many of these adverse consequences to cognition may continue and progress throughout life."

For the study, rodents were subjected to charged particle irradiation (fully ionized oxygen and titanium) at the NASA Space Radiation Laboratory at New York's Brookhaven National Laboratory and then sent to Limoli's UCI lab.

Six months after exposure, the researchers still found significant levels of brain inflammation and damage to neurons. Imaging revealed that the brain's neural network was impaired through the reduction of dendrites and spines on these neurons, which disrupts the transmission of signals among brain cells. These deficiencies were parallel to poor performance on behavioral tasks designed to test learning and memory.

In addition, the Limoli team discovered that the radiation affected "fear extinction," an active process in which the brain suppresses prior unpleasant and stressful associations, as when someone who nearly drowned learns to enjoy water again.

"Deficits in could make you prone to anxiety," Limoli said, "which could become problematic over the course of a three-year trip to and from Mars."

Most notably, he said, these six-month results mirror the six-week post-irradiation findings of a 2015 study he conducted that appeared in the May issue of Science Advances.

Similar types of more severe cognitive dysfunction are common in brain cancer patients who have received high-dose, photon-based radiation treatments. In other research, Limoli examines the impact of chemotherapy and cranial irradiation on cognition.

While dementia-like deficits in astronauts would take months to manifest, he said, the time required for a mission to Mars is sufficient for such impairments to develop. People working for extended periods on the International Space Station, however, do not face the same level of bombardment with galactic cosmic rays because they are still within the Earth's protective magnetosphere.

Limoli's work is part of NASA's Human Research Program. Investigating how space radiation affects and learning ways to mitigate those effects are critical to further human exploration of space, and NASA needs to consider these risks as it plans for missions to Mars and beyond.

Partial solutions are being explored, Limoli noted. Spacecraft could be designed to include areas of increased shielding, such as those used for rest and sleep. However, these highly energetic charged particles will traverse the ship nonetheless, he added, "and there is really no escaping them."

Preventive treatments offer some hope. Limoli's group is working on pharmacological strategies involving compounds that scavenge free radicals and protect neurotransmission.

Explore further: Long-term galactic cosmic ray exposure leads to dementia-like cognitive impairments

More information: Scientific Reports, DOI: 10.1038/srep34774

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TheGhostofOtto1923
5 / 5 (4) Oct 10, 2016
Mark Thomas
3.7 / 5 (3) Oct 10, 2016
One approach to cutting interplanetary radiation exposure in half is to go twice as fast on average. Nuclear rocket engines and adding in situ propellant for the return trip at Mars would enable that kind of performance until we eventually develop even better propulsion. Better still, less time in space means more time on Mars between opposition launch windows. Getting your crews to Mars with less radiation exposure in combination with months of additional time on the surface is a very attractive combination.

cantdrive85
1 / 5 (6) Oct 10, 2016
It would seem that astrophysicists merely studying these topics causes them to suffer from these afflictions.
jonesdave
5 / 5 (7) Oct 10, 2016
It would seem that astrophysicists merely studying these topics causes them to suffer from these afflictions.


Lol, from the people who believe Earth used to orbit Saturn, and that interplanetary lightning bolts blow mountains off of planets to become comets. Hypocrisy, much?
promytius1
not rated yet Oct 10, 2016
Thanks for article and also for the insights/details of regular aging, which I thought you covered well.
KelDude
4 / 5 (5) Oct 10, 2016
How about turning the "ship" into a large magnet like earth so the ship is contained inside the magnetic bubble thus protecting the inhabitants. Ever heard of "shields up" before. This is one "shield" that would be fairly straight forward and probably work. This is not out of the box thinking, star trek thought of it. We just need to explore and develop it.
jonesdave
5 / 5 (1) Oct 10, 2016
How about turning the "ship" into a large magnet like earth so the ship is contained inside the magnetic bubble thus protecting the inhabitants. Ever heard of "shields up" before. This is one "shield" that would be fairly straight forward and probably work. This is not out of the box thinking, star trek thought of it. We just need to explore and develop it.


Has actually been thought of: http://arc.aiaa.o...012-5114
I've only read the abstract, so don't know if that is for regular solar radiation, flares, CMEs, or whether it includes protection from cosmic rays as well.

A few more papers mentioned in this article:
http://space.stac...-require
Osiris1
not rated yet Oct 11, 2016
How about developing maybe first a compact high energy nuclear reactor maybe based on a pebble bed or thorium cycle to provide MW of power for electric or M2P2 or VASIMR thruster power, or wait for a focus fusion device that doubles as a rocket AND magnetoelectrohydradynamic power traveling conductor generator and produce 5 magnitudes more thrust and power, scalable for limiting space speeds to a few million miles per hour to allow for deceleration. Then we could make a ship, in space, big and bad as we want so we can drive whereever we want on our time. Hydrogen and boron are common in our system so refueling from asteroid mining possible. Slow rotation of large toroidal crew quarters provides artificial gravity without vertigo. Fuel storage around crew toroid =shielding. Use small focus fusion thruster in Mars shuttle craft for safe low V landings/take offs. Later HiOutput FF thrusters could shuttle on/off Earth too. All possible to Can Do minds.
antialias_physorg
5 / 5 (1) Oct 11, 2016
hether it includes protection from cosmic rays as well.

It doesn't. Magnetic fields only protect you from alphas and betas (charged forms of radiation). Gammas are photons and aren't affected by magnetic shields.

Much worse: gammas can create secondary radiation like betas on impact (e.g. when they impact the wall of your ship) and shower the crew with them. Betas are much more dangerous (in terms of causing cancer) than gammas.

A way around the long radiation exposure/weight issue might be to land on the Moon, print yourself a hull made out of moon rock and take back off for your trip to Mars. E.g. by this method:
http://www.space....ase.html
(or better: print just the hull, launch it into Moon orbit and rendezvous with it there).
Hull weight increases with thickness squared, but radiation exposure goes down exponentially with thickness. So there is a point when the added travel time (due to weight) would be worth it.
Sonhouse
5 / 5 (2) Oct 11, 2016
Like Osiris said, go faster, get there in one week, minimum rad damage. IF you could accelerate at one g halfway and decel the rest of the way, you get there with zero relative velocity and it takes only a few days and you don't worry about Hoffmann orbits and all that low velocity stuff, just go in more or less a straight line. You just aim to where the planet will be in a week or whatever time is involved.

The hard part of course, is getting that 1 g of constant accel. But if you do manage that, interplanetary travel will be more like ocean liner times to get to other planets and it doesn't take much longer to go ten times further because your velocity increases every second.

It would certainly work for our solar system, since it takes about one year at one g to get close to c so any voyage in the solar system would be way under c velocity.

Of course if you hit something doing 10,000 km/sec, you would be in trouble but you would get there fast!
antialias_physorg
3 / 5 (2) Oct 11, 2016
Of course if you hit something doing 10,000 km/sec, you would be in trouble but you would get there fast!

Rough calc shows me that a constant 1g acceleration would get you up to 1400km/sec until the average halfway point till Mars (roughly 10^11m distance)
...and you would have to accelerate for roughly 40 hours constant. While this means the flight time to Mars would be slightly more than 3 days any kind of fuel calculation will show that this is in no way feasible (Tsiolkovsky rocket equation gives me a ludicrously large number).

And no, strapping an ion engine to a nuclear reactor won't get you a 1g acceleration either, because ion drives - while having high specific impulse - have a very low thrust. And nuclear reactors are HEAVY.

Think about the Star Trek Enterprise. If that thing were to undock using its 'ion engines' the entire movie would probably be spent watching the thing move a couple of meters at best)
Mark Thomas
3 / 5 (2) Oct 11, 2016
AAP is correct that we don't have anything right now that can accelerate at 1g for 40 hours. Fusion is a great idea whose time is yet to come, as is ACMF.

Both Zubrin and Musk advocate using chemical rockets and Mars-produced fuels to return. However, both also acknowledged that nuclear thermal rocket (NTR) engines are preferable because of better performance. NTRs combine high thrust and high specific impulse with a potentially wider range of propellants.

Zubrin was a nuclear engineer and advocates use of NTR later on, but he fears its more lengthy development phase would entail greater political risk which might derail the whole Mars project. Zubrin may be right, but it might prove preferable to have a reusable NTR-powered interplanetary spacecraft in space when the next recession or political snafu occurs. That way the incremental cost of continuing a Mars program would be reduced because of the greater sums already spent (sunk cost).
Mark Thomas
3.7 / 5 (3) Oct 11, 2016
"Think about the Star Trek Enterprise. If that thing were to undock using its 'ion engines' the entire movie would probably be spent watching the thing move a couple of meters at best)"

NX-class Star Trek Enterprise has three forms of propulsion, 1. Thrusters; 2. Impulse Engines (not ion); and 3. Warp Drive.

Perhaps we should consider the Star Trek perspective on occasion, if for no other reason than it might give clues on the all-important public perspective. For example, Star Trek fans want an advanced spaceship that can travel very fast and safely deliver its crew to an alien world ready for action. We don't want our astronauts overly irradiated with weakened bones, etc., from spending too much time in a pathetically slow spacecraft using mostly outdated technology. Star Trek fans want to BOLDLY go where no one has gone before.
Zzzzzzzz
1 / 5 (1) Oct 11, 2016
Perhaps some sort of helmet?
https://www.amazo...141P8WHC


May as well go for the telepathic resistance while we're at it
dan42day
4.5 / 5 (2) Oct 11, 2016
Nuclear power would provide for both magnetic shielding and faster transits.
Mayday
1 / 5 (1) Oct 11, 2016
Would filling the ship with water reduce the radiation dose? If so, what thickness/depth of water shielding would be required to adequately reduce the danger? Yes, there would be a ludicrously massive weight penalty, but you might live, right?
TheGhostofOtto1923
5 / 5 (1) Oct 11, 2016
Rough calc shows me that a constant 1g acceleration would get you up to 1400km/sec until the average halfway point till Mars (roughly 10^11m distance)
...and you would have to accelerate for roughly 40 hours constant. While this means the flight time to Mars would be slightly more than 3 days any kind of fuel calculation will show that this is in no way feasible (Tsiolkovsky rocket equation gives me a ludicrously large number).
-Snore.

"Human interplanetary missions with the VASIMR® require power levels in the multi-megawatt for reasonably short transit times.. As we show in this paper, a 12 MW mission can take less than 4 months and a 200 MW mission less than 2 months. The nominal parameters for these missions are variable specific impulse, Isp, from 4,000 to 30,000 s with a total power efficiency, of 60%, and a specific mass, α (total), less than 4 kg/kW." Ad Astra Rocket

Osiris1
5 / 5 (1) Oct 11, 2016
I like input of using water as shielding. Like Stephen Hawking says, space is littered with water so we can get all the water we want in space and not have to pay the cost of lifting it off of deep gravity wells. Using a fusion power and propulsion system would yield infinite power as long as one scales the focus fusion reactor large enough to take enough fuel...hydrogen and boron. Boron is plentiful in asteroids and small objects. With focus fusion we can live in space and refuel in space. Agriculture is byproduct of energy so hydroponics bays a la Star Trek would sustain us here. We get a lot of boron, add it to the shield like a 'fuel tank'. Large enuf reactor with terawatts of power, a bussard collector, etc. and boundless fuel supply we can go anywhere. Take maglev shuttles powered by microwave beams from the ship and land in any gravity well and leave it as well.
optical
Oct 11, 2016
This comment has been removed by a moderator.
humy
not rated yet Oct 18, 2016
Sending a man to Mars is currently a very bad idea anyway and it will remain a bad idea for a very long time.
It is just to risky and of absolutely no practical benefit nor even to the benefit of science as it would be easier and better to develop and send unmanned probes or even A.I. there to study the planet. The MASSIVE costs of completely pointlessly sending a man there could always be better spent on other things such as ending world poverty etc.
We should wait until we ended all the world's serious life-or-death problems and global warming problem etc, however long that takes, before sending a man anywhere in space; only then might I agree with it.
humy
not rated yet Oct 18, 2016
The willingness for Mars travel already implies some level of dementia of people involved, so that it cannot make such a damage.

yes!
What possible rational reason could someone have to choose to leave the comparative paradise of Earth to a cold barren desert wasteland which doesn't even have a breathable atmosphere and with a massively dangerous journey there at that!?
Mars is more hostile than the center of Antarctica; at least the center of Antarctica has a breathable atmosphere so it would actually be LESS completely insane to pointlessly won't to go there than to Mars!
katesisco
1 / 5 (1) Oct 23, 2016
What conclusion should we draw from the continuous warfare here on planet Earth?
What caused the collapse of the Early Copper Age and its replacement with a dumbed-down population? Why did past societies created underground cities and make deep rock cutting for 40 foot below grade roads?
Is the experimentation with high energies at CERN a hope to discover a way to warp space/time?
Are we not experiencing massive bombardments of cosmic rays and dangerous UV levels? If the smarter us could not leave planet Earth, it is unlikely that we will. Einstein was wrong about world war producing a demented society; we have already become that thanks to our solar alignments past, present and pending.
Sonhouse
not rated yet Oct 24, 2016
Sending a man to Mars is currently a very bad idea anyway and it will remain a bad idea for a very long time.
It is just to risky and of absolutely no practical benefit nor even to the benefit of science as it would be easier and better to develop and send unmanned probes or even A.I. there to study the planet. The MASSIVE costs of completely pointlessly sending a man there could always be better spent on other things such as ending world poverty etc.
We should wait until we ended all the world's serious life-or-death problems and global warming problem etc, however long that takes, before sending a man anywhere in space; only then might I agree with it.

The benefits of going to Mars outweighs the downsides. For instance, if life is discovered there, just bacteria or some such, it completely changes the course of evolutionary science here on Earth, which you probably don't believe in anyway, but the technology that has to be developed to get the job done will benefit humans.
Sonhouse
not rated yet Oct 24, 2016
I think the first pioneers to Mars will accept the risks including dementia. There will be no one week trips or one month trips in the 21st century, they will ALL be months long with the associated risks till we get fusion or anti-matter rockets (which is further along engineering wise than fusion, the biggie is getting anti matter to fuel the thing, which may be solved in a hundred years or so). Eventually we will have week long trips to Mars and the next thing for Mars is an artificial magnetic field, a superconducting ring around the Martian equator can give a planet wide field that will protect the whole planet which will be absolutely needed if we want to grow crops on the surface, otherwise it will be tunnel city forever till the planet wide magnetic field is figured out. If we ever get 1 g rockets that runs for a month or so we will have the solar system in our back pockets. Get to 600 AU and we use sol as a lens.

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