'Space Brain': Mars Explorers May Risk Neural Damage, Study Finds (nbcnews.com)

An anonymous reader quotes a report from NBC News: Astronauts making a years-long voyage to Mars may get bombarded with enough cosmic radiation to seriously damage their brains, researchers reported Monday. The damage might be bad enough to affect memory and, worse, might heighten anxiety, the team at the University of California Irvine said. It's the second study the team has done to show that cosmic radiation causes permanent, and likely untreatable, brain damage. While their experiments involve mice, the brain structures that are damaged are similar, they write in the Nature journal Scientific Reports. NASA knows that astronauts risk physical damage from the radiation encountered in space. Earth is enveloped in a large, protective sheath called the magnetosphere, which deflects a lot of the ionizing radioactive particles that speed through space. Teams aboard the International Space Station are inside that envelope. But moon travelers were not, and this summer a study showed the cosmic radiation may have damaged the hearts of many of the Apollo program astronauts. A trip to Mars would expose astronauts to even more radiation -- enough to cause cancer, for sure, and now this research suggests brain damage, as well. They bombarded mice with the same type of radiation that would be encountered in space, and then looked at what happened to their brains. It did not look good. The changes were seen in the connections between brain cells and in the cells, as well. "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."

Comments

radiation is the big stumbling block

[Anonymous Coward]

for interplanetary space travel. time to research some magnetic shielding, asap.

Re:radiation is the big stumbling block

[Rei]

Magnetic shielding (on practical scales) is not effective against GCR, only solar. The article talks about GCR.

IMHO, SpaceX probably has the right solution to radiation: go fast. If you have to bring up extra mass anyway, you might as well make that mass be fuel to shorten the trip rather than inert shielding for a long coast (although there clearly is *some* balancing point; paper-thin walls won't do, even on a short-trip). Also, their solution of "go big" is probably right, as surface area to shield rises propotional to the radius squared but internal volume (and mass / payload capacity of boosters) rises proportional to the radius cubed (assuming proportions are kept roughly the same on all three axes). The bigger your crew transport vehicle, the lower the percentage of its mass that needs to be dedicated to shielding to achieve the same result.

But there's no question that radiation is one of those issues that we really don't have a good "magic bullet" for.

Re:radiation is the big stumbling block

[Joce640k]

Standard issue tinfoil helmets should work.

Re:radiation is the big stumbling block

[The Real Dr John]

Face it, until they figure out how to fully shield the spacecraft, this is not practical for humans. It will probably require actual physical shielding if you really want to stop all harmful exposure. That means lots of heavy metal, which is not good for spacecraft getting into orbit. So it would have to be built in orbit. That means we are talking a long time from now (like 50 or more years). Telepresence is the best we are going to be able to do in the near future, which is fine by me. I like being inside the earth's magnetic bubble. It's cozy.

Re:radiation is the big stumbling block

[Rei]

Not exactly. Ideal shielding is relatively thin metal followed by lots of hydrogen-rich material, plus a small amount of neutron absorbers (boron, etc). The hydrogen-rich material should make up the majority of the mass. This can be hydrogen-rich plastics (such as polyethylene), liquid hydrogen propellant (great ISP, although storage is difficult), methane propellant (what SpaceX plans to use, albeit they don't call for much during coast), ammonia (coolant, easy hydrogen store), water (need it anyway, even easier to store), hydrazine (commonly used for RCS thrusters), etc. NASA has been looking at trying to make structural composite materials out of hydrogenated boron nitride nanotubes, which would be killing two birds with one stone (since they're strong as well).

The reason you need lots of hydrogen is that a lot of your high energy impacts will often kick off neutrons, and these are much harder to block than ionized particles (this is particularly of concern with GCR and high-energy solar flare protons). The best way to eliminate neutrons is to moderate them down to the thermal spectrum so that they can be readily absorbed by high cross section absorbers. Hydrogen is by far the best neutron moderator per unit mass; nothing else really even comes close. It has a fairly high scattering cross section to begin with, and scatters far more per event than other compounds due to its low mass (more energy transfers from the neutron to the hydrogen), and presents far more nuclei to scatter from per unit mass than other elements. Liquid hydrogen is even better because you're thermalizing to a very cold temperature, which dramatically increases absorption cross sections (whether from hydrogen itself, or elements specifically used as absorbers such as boron). But again, liquid hydrogen is more difficult to store than other forms....

Re:radiation is the big stumbling block

[iris-n]

I think you are severely overestimating the danger of radiation. NASA measured the radiation dose received in 180 day trip to Mars to be about 330 mSv. This is probably enough to increase long-term cancer risk, but little else. Check the xkcd about radiation.

Re:radiation is the big stumbling block

[amiga3D]

That's about 15 times the annual exposure allowed for US Nuclear plant workers. And that's just one way not to mention the increased exposure on Mars. I suppose it wont kill them during the trip there and back but I'd bet it would take a couple of decades off their lifespan.

Re:radiation is the big stumbling block

[amiga3D]

Exploring the solar system is dangerous. At least if you want to do it in person. Rovers not so much.

Re:radiation is the big stumbling block

[The Real Dr John]

I thought boron was one of the best neutron absorbing materials.

Re:radiation is the big stumbling block

[iris-n]

According to the comic I linked, the allowed dosis for radiation workers in 50 mSv, making the trip to Mars about 7 times it. But this dosis is set to a level that is certainly safe, it doesn't mean that higher than it is certainly unsafe, just that we go into a gray zone where we can't guarantee it's safe, but we do not know whether it is actually dangerous either.

According to this table you need to be subjected to 1000 mSv in a short burst to have a 5% chance of developing a fatal cancer, which would make the 330 mSv over six months seem rather safe. I would be happy, however, if you could find a better source with more detailed information.

Re:radiation is the big stumbling block

[Rei]

Absorbing, not moderating. You have to moderate neutrons down from the MeV range to the thermal range in order to raise the absorption cross sections to reasonable levels - even with high cross section absorbers like boron.

Re:radiation is the big stumbling block

[The Real Dr John]

So maybe a double jacket would work. I am not an engineer, I am a neuroscientist, so I worry about the brain, and protecting that. I would never go to Mars myself unless there was full shielding against all significant radiation damage. I understand there are lots of people who wouldn't care because they think they can take it and survive, but the increased cancer risk and potential for brain damage should worry everyone.

Re:radiation is the big stumbling block

[Rei]

The estimated exposure for a 400 day round trip transit and 560 days on the surface with 5g/cm2 aluminum shielding is 1070mSv with a 4.2% increase in death rate for men / 5.1% for women, and for 20g/cm2 aluminum it's 960mSv with an increase of 3.4% for men and 4.1% for women. But there's caveats that make this effectively higher, see below. Additionally, both of these are for solar minimum with no solar storms. The big problems however come when you have major charged particle events. If you don't budget for the mass for it, then you're playing dice with your crews' lives, so you pretty much have to. Events that give enough dose to significantly increase the mortality rate (ex. the August 1972 event) are not rare. And while rare, some events are powerful enough to cause acute radiation poisoning and even death in short (30 day) timeframes (4x the August 1972 event). The probability of the former is estimated at 0.2% per week, while the latter is estimated at 0.01% per week.

Re: the comic: XKCD vastly oversimplifies the situation. Radiation risks are not limited to "100mSv: lowest one-year dose clearly proven to increase cancer risk" levels. Radiation is also tied to a wide range of other diseases beyond cancer (cataracts, cognitive decline, lung damage, heart disease, etc), and the level "clearly linked" to cancer does not mean "there is no cancer beyond this point". Specifically concerning cancer: The NCRP-98 / NCRP-132 recommended limits for blood-forming organs are 250mSv/mo, 500/yr, 400-2900/life (depends on age and sex; young and female = less, old and male = more). These limits are based around a calculated excess 3% risk of developing fatal cancer. However, they are misleading because the error bars are large, and the upper end of the error bars is much more likely to kill you than the lower end - so if you want a 95% confidence interval, the risks from such figures are about 3 times higher than the mean suggests. Additionally, wherein the odds of dying from cancer are 3%, the odds of contracting cancer are inherently higher, since - especially in the presence of modern medicine - not all cancer is fatal.

Furthermore, studies with astronauts and animal models keep suggesting more problems from radiation in space than had previously been assumed, and we know little of the effects of the radiation environment beyond LEO. Simplistic radiation models that treat all types of radiation damage from a certain category "grouping" as equivalent appear thusfar to be inaccurate.

You will not find any researchers working in the field of studying the radiation health risks to astronauts who feel that the case is overblown. It is very much considered a significant problem that remains to be solved. Unless you're fine with willingly compromising travelers health and risking their outright survival in the case of a severe solar event, wherein, there's no problem, you can go ahead and launch ;)

Re:radiation is the big stumbling block

[HangingChad]

The reason you need lots of hydrogen...

What about using water? They have to carry water as a consumable anyway, could you store in thin panels in the walls or as ice and get any decent shielding effect or is water not hydrogen dense enough?

Re:radiation is the big stumbling block

[Rei]

Indeed, most plans call for varying materials - and not just with respect to the inside/outside, but also with where they are on the spacecraft. Even the passengers' own bodies act as shielding for other other passengers and needs to be taken into account. Modeling radiation and health risks on interplanetary missions is not a simple task!

If anyone wants to get more of a sense of how cross sections of different elements / isotopes can vary with different types and energies of radiation, I strongly recommend the Sigma server. Start off with neutrons (although you can change that in the dropdown on the top right), pick an isotope, then look at the options on the right. You'll see lots of entries of the form (n, X). The first part in the parentheses is what the incoming particle is; the second part is what the heaviest outgoing particles are. (n,gamma) for example means that there are no nucleons that result from the collision, only gamma; this is a simple neutron-capture transmutation. (n, total) means the total of all cross sections; (n, elastic) is elastic scattering (the dominant method of moderation at low energies; follows the same sort of energy/angular momentum distribution as elastic collisions between objects on macroscopic scales); (n, inelastic) is inelastic scattering (an additional loss mechanism at high energies where the particle is absorbed and then re-emitted, with a more complex energy distribution), etc. Click on "plot" for any category and it'll show you the result.

For example, here's the (n,alpha) for 10B, a well known neutron absorber. And indeed, these are very high cross sections compared to, say, the odds of elemental carbon doing anything to get rid of the neutron. But note how vastly higher the cross sections are in the thermal (meV) spectrum than they are in the fast (MeV) spectrum. Even with boron, you're unlikely to capture fast neutrons (MeV range or higher) except with a great thickness of absorber. But if you moderate them down - moderation having a high cross section - then they become easy to capture. Remember when looking at these charts that 1H is also 1/10th the molar mass of 10B.

On the other hand, low-Z (light) materials aren't that great at blocking certain types of radiation - if you want to block EM radiation spectrum, for example, you want high-Z materials (that's why there's the standard "lead apron" for getting an x-ray). But the balance of effects in space turns out to favor the need for low-Z materials.

If the terms above like "cross sections" are unfamiliar... picture a particle of any type of radiation like a baseball pitched randomly toward an area where someone has hung a bunch of spheres. What's the odds that the baseball is going to hit one of them? Well, it depends on the cross section that they present to the ball. While a naive expectation might be that it would just simply be proportional to the size of the atoms, in practice different isotopes vary widely in their different effective cross sections to different particles and different reactions. Still, cross sections are measured in "barns", which is a unit scaled to be roughly the size of typical atomic physical cross sections for comparison purposes. Anyway, you can just read nuclear cross sections as "how likely a reaction is per unit traveled through the target".

Oh, and I forgot to mention one other thing: when picking shielding materials, neutron capture or other transmutation reactions alter the isotope that they hit. Often what they produce will be unstable and will decay - sometimes multiple times - releasing more radiation. So it's also important to look

Re:radiation is the big stumbling block

[amiga3D]

This is the quote I read....

"The Mars rover Curiosity has allowed us to finally calculate an average dose over the 180-day journey. It is approximately 300 mSv, the equivalent of 24 CAT scans. In just getting to Mars, an explorer would be exposed to more than 15 times an annual radiation limit for a worker in a nuclear power plant."

Sadly though, when I do the math the 15 times is obviously a mistake, they probably meant that figure for a round trip. I'm sure 50 isn't that big a deal as they would err on the safe side but 300 is not even close. And as I said that's for one way and not counting the stay on Mars itself which also has issues with GCR. I think the issue can be managed but I suspect it'll be 5 decades or more before we're up to anything on that scale. And that assumes we don't manage to blow ourselves up before it happens.

http://www.space.com/24731-mar...

Re:radiation is the big stumbling block

[Rei]

I checked the last three papers under "magnetic shielding papers" on that page. None of them say anything to suggest that active shielding is an effective means to shield from GCR. They're also all quite old, there's much more recent research on the topic.

They do mention what I wrote - that active shielding is probably mass effective against SCRs (but needs more research). But it's very doubtful that it could be mass effective against GCR. The gyroradius of a particle is proportional to its energy and inversely proportional to the magnetic field strength. GCR is very high energy (commonly hundreds of MeV, up into the tens of GeV range in relevant amounts, with virtually no limit on the extremes), so you have to scale up the size of your magnet proportionally. To oversimplify, if you wanted to take a magnetic shield for the solar wind (commonly a few keV, up to a few dozen) and scale that up to shielding from solar storms protons (hundreds of keV to a few MeV), you'd have to increase it's scale 100fold; and to go from there to GCR would be another hundred-fold increase.

That is of course an oversimplification (even on Earth you can't just scale magnet masses like that, and it's more complex in space because you're actually making a mini-magnetosphere), but you get the gist. It's really hard to shield from GCR-energy particles.

Re:radiation is the big stumbling block

[iris-n]

I said that The Real Dr John specifically was overestimating the danger. He said "until they figure out how to fully shield the spacecraft, this is not practical for humans". And I really don't agree that "~5% increase in death rate" equals "not practical for humans". You have to put things in perspective: just the launch itself has a ~5% probability of killing the astronauts, so while a further 5% increase in the death rate is certainly not welcome, it is one additional danger of an already quite dangerous task. I think you'll find very few astronauts that refuse to take this risk.

That said, of course we need to reduce the radiation exposure as much as we can, because having astronauts who are dead, or with cancer, or with cataracts, or stupid, or with lung problems, or with heart disease is clearly not desirable. Going for extra shielding, as The Real Dr John suggested, is a terrible idea. You need a crazy amount of shielding, on the order of 100 g/cm, to significantly reduce the exposure, so waiting for that to happen is to wait forever. So I think the only plausible solution in the near term is to go fast.

In this respect I find Musk's proposal quite reasonable. He intends to do the trip in 90 days, and rotate the spacecraft to use to fuel tank as a shield during solar flares. NASA calculates that 5% from the 330 mSv in the trip would come from solar flares, so cutting that out and using the shorter trip time already reduces your pessimistic 1070 mSv to 650 mSv, so about 325 mSv per year, already well below the recommended level you quote.

Re:radiation is the big stumbling block

[Grishnakh]

I agree about needing to build spacecraft in orbit (or at a Lagrange point), however 50 years is either too long or too short. If we'd actually get off our asses and start developing our asteroid capture and mining capabilities and doing refining in space or on the Moon, then we could probably start building large, heavy (and heavily shielded) things in space in a decade or two. But at the rate we're going now, I expect this won't happen for a few centuries at the very soonest, and probably never to be honest.

Re:radiation is the big stumbling block

[swamp_ig]

The bulk of humanity will never leave the Earth, ever. Just the energy cost of getting all that mass to orbit is prohibitive, and even if you send up a good fraction, the remainder will just keep breeding ensuring you'll never catch up.

Shields up!

[Anonymous Coward]

Sounds like they need to invest in a really big electromagnet to put on their space ship to divert radiation. And they are allowed to call it a 'shield'.

Re:Shields up!

[hcs_$reboot]

Make the spacecraft out of lead.

Re:Shields up!

[Nutria]

Because you need a hell of a lot thinner lead shield than mangetosphere.

Re:Shields up!

[Oligonicella]

Second sentence true, first sentence false.

Re:Shields up!

[Smidge204]

Mangetosphere has no mass. The generating equipment does, but it might be less than the mass of the lead (I haven't done the math of course) and likely much more compact.

OTOH you could shield the craft with a jacket of water, which you'll need anyway and is an excellent radiation shield.
=Smidge=

Re:Shields up!

[Nutria]

The generating equipment does

But requires energy.

It's all a balancing act that I don't think humans will solve until/if they master really compact fusion generators.

Re:Shields up!

[perpenso]

Human's can't make magnets. We don't even know how they work.

You never wrapped wire around a big-ass nail and connected it to a 6V battery?

I believe there are mechanical methods too, for example rubbing a sewing needle with silks/wool/etc to make a compass needle. Did that in scouts long ago.

I have some faint recollection of something involving hammering but it was never demonstrated or tried, just mentioned.

Re:Shields up!

[sg_oneill]

Maybe not lead (Lead is heavy!) but perhaps some sort of faraday cage might do the job?

Re:Shields up!

[jeillah]

Tin foil hats?

Re:Shields up!

[Joce640k]

You never wrapped wire around a big-ass nail and connected it to a 6V battery?

Where do I get a 6V battery?

Re:Shields up!

[NotAPK]

The magnetosphere does not shield against high energy cosmic rays. You need mass density, and on Earth that shielding is provided by the atmosphere.

There's no point burning fuel rushing to Mars to minimise exposure to cosmic rays, since the atmosphere on Mars is too thin to provide any protection. So the only safe option is to make the entire round trip as short as possible. It just seems so difficult to do with current rocket technology...

Re:Shields up!

[Anonymous Coward]

You never wrapped wire around a big-ass nail and connected it to a 6V battery?

Where do I get a 6V battery?

Amazon and most stores that have a camping/sports section carry them. They are called lantern batteries and are the large cube looking battery. We used them all the time for electronic/electrical experiments because one connector is a large spring and the other had a screw cap (I think, too many years ago) and did not require any special connectors or soldering to wire the project.

Re:Shields up!

[Rockoon]

Where do I get a 6V battery?

Walmart.

Frequently called a "Lantern Battery"

Re:Shields up!

[NotAPK]

You can hit a needle with a hammer and the shocks allow the randomly oriented domains to align, either to the largest domain in the material, or a weak external field, such as that from the Earth. It's not instant, and you won't get everything lining up as neatly as you would by applying a strong external field. But the resulting magnetism is measurable and may be useful, depending on what your needs are. Here's some more info.

Re:Shields up!

[thinkwaitfast]

What's heavier, a pound of lead or a pound of feathers?

You need less lead than feathers to shield from radiation. If you do the math, lead requires the least mass.

Re:Shields up!

[Applehu Akbar]

But when you reach Mars, there is soil available to pile up around your habitat. To minimize the amount of digging required, early explorers will make use of these:
https://www.google.com/search?...

Re:Shields up!

[Smidge204]

But requires energy.

You have options for that.

On the other hand, a ship with tons of lead shielding will need proportionally more fuel.
=Smidge=

Re:Shields up!

[amiga3D]

Actually for GCR water and fuel make better shielding. Since you have to take it with you anyway......

Re:Shields up!

[Grishnakh]

I don't know what kind of battery you're thinking of, but a standard 6V lantern battery has two spring contacts, and that's it, no "screw cap". Here's a Wikipedia article about them that shows a 6V lantern battery in the first picture. They use springs because they work well in a flashlight with poor manufacturing tolerances and which can be subject to a lot of bumping and jostling and being dropped. You might be thinking of the protective plastic caps that are normally found on top of the springs when you first buy the battery. Those are just there so it doesn't get shorted out.

Re:Shields up!

[Grishnakh]

This is merely the level of quality we can expect from Slashdot these days.

Honestly, I wish they'd just ban AC postings. They served a purpose in the past in case people wanted to inform about things without revealing their identity (which could be done by correlating with other posts under the same pseudonym). But no one really posts anything all that useful here these days, since most of the quality posters have abandoned this site. Banning ACs would help bring some semblance of quality back to the site by eliminating the numerous trolls.

Re:Shields up!

[Rei]

Just take a 9V battery and turn it upside down.

Re:Shields up!

[Grishnakh]

Ok, I just googled this and it appears to be untrue. Snopes even has a page about it. It might be true for certain brands, but I wouldn't count on it; the stuff I read said that most 6V lantern batteries have 4 "F" cells inside, which aren't very useful to most people.

Re:Shields up!

[david_thornley]

The ISS is above the atmosphere, so its only protection for the hemisphere away from Earth is the magnetic field, and we keep some people there for a year. They aren't in good shape then, but I haven't seen complaints about radiation.

Is there something I'm missing here, or is the ISS a good approximation to an interplanetary spaceship to within a factor of 2?

Re:Shields up!

[david_thornley]

Yeah, a kilogram of gold weighs as much as a kilogram of feathers, but that's not true of a pound of gold vs. a pound of feathers*. Another reason to go metric.

*Feathers use the normal pound, gold at least traditionally used the somewhat lighter troy pound.

Re:Shields up!

[Nutria]

Actually for GCR water and fuel make better shielding.

How thick a layer of water?

Re:Shields up!

[amiga3D]

That's a problem for engineering. However I have Google which leads to a site that tells me it'd need to be 1 meter thick. A lot of water requiring many rocket trips to get it to orbit since for the likely vehicle required to make the trip to Mars that'd be about 330 metric tons. To put into perspective a Saturn V, a very large booster, can put 120 of those metric tons into orbit in one trip so figure 3 trips just for the water required. Back in the early 70s the cost of launching a Saturn V to orbit was in the range of nearly 200 million dollars. I shudder to think what that would cost today. Most likely they would use many launches by smaller vehicles to save money but it'd be some expensive water. I'm sure they would have recycling to keep from losing their shielding.

Re:Shields up!

[Nutria]

Saturn V, a very large booster, can put 120 of those metric tons into orbit in one trip ...
I shudder to think what that would cost today.

That's why this problem won't be solved until small, cheap fusion reactors are created.

Re:Shields up!

[NotAPK]

No, I under-estimated the shielding effect of the Earth's magnetic field. It's a relatively weak field, but it's massive, and this is sufficient to bend cosmic rays away from the Earth. To use the same approach on an object the size of a spaceship is infeasible due to the high strength field required, which is why I made my original claim that you don't use magnets for shielding.

There's a good article on Wikipedia about health effects from cosmic rays. The human on the ISS for 6 months receives an order of magnitude more radiation than a human on the surface of the Earth, but on a round trip to Mars a human will receive an order of magnitude more radiation than 6 months aboard the ISS.

Re:Shields up!

[PlaynBass]

A mass like water could be accelerated using a rail gun, or perhaps in a beanstalk sort of straw of balloons, using solar powered evaporators to keep the H20 rising, at least to the top of the atmosphere, where specialized spacecraft could swoop down to take the load the rest of the way to orbit.

Re:Shields up!

[amiga3D]

Sure, sometime after 2150.

Re:Shields up!

[PlaynBass]

Once your craft is out of a planetary gravity well, most of the heavy lifting is done. Three or more transports would make the trips more of a routine, and would allow for scheduled return trips, trade and tourism. Water-fuel storage would be integrated into the shielding of the vessels, but once the transports are up to speed, they should make Rendezvous at suitable Solar or planetary LaGrange points for refueling and transfer personnel and cargo, rather than in orbit around a specific planet to reduce the fuel requirements. Water (and probably a lot more) will be mined from high-value asteroids, which have been nudged into more convenient orbits using the guided mass of tethered gravity-slings to maneuver the asteroids' mining operations to one of the LaGrange points. Long-term use of space requires a wider view of the time and distances required. Creating well-stocked Trading Posts can alleviate the need to go to the store on Earth for every little thing... the Trading Posts themselves can be Orbital, allowing for a rendezvous at any point along the route. Interplanetary orbital routes can make use of opportune gravity wells to conserve fuel, or reduce transit time. Not all cargo vessel need to be "man-rated"...

Its already been proven 20 + years ago

[future assassin]

https://www.youtube.com/watch?...

Re:Its already been proven 20 + years ago

[Anonymous Coward]

"This video contains content from B_Viacom, who has blocked it in your country on copyright grounds."

That's no proof!

Re:Its already been proven 20 + years ago

[hcs_$reboot]

Where do you live?

Re:Its already been proven 20 + years ago

[BESTouff]

France here, same problem. Thank you modern internet.

Re:Its already been proven 20 + years ago

[michelcolman]

Yep, same in Belgium.

And then some wonder why people have such a negative opinion on media conglomerates. Refusing legal access based on where you happen to be and then suing "pirates" if they get around the restrictions, way to go to create a nice brand image.

Re:Its already been proven 20 + years ago

[reboot246]

That was one of my favorite shows. I could watch it over and over and still laugh my ass off.

But a worse threat to long-term space travelers is that they might Start . . . Talking . . . Like . . . William . . . Shatner.
Perfect evidence of brain damage there!

If they think it's viable...

[goose-incarnated]

If they think it's viable then then already have neural damage. A little more won't make much of a difference.

Re:If they think it's viable...

[CrimsonAvenger]

Let's try a novel approach to the problem.

1. If you don't want to go to Mars, don't.

2. If someone else does, it's their problem. They're not asking you to be their Mommy and tell them what's good (or bad) for them, anymore than you're asking them to be your Mommy....

Done. Problem solved.

And as an extra bonus (for one group or the other), someone will get to tell someone else "See!? I Told You So!"

So a win-win situation, in general. Yeah, you lose the "I told Wilbur and I told Orville that that thing would never fly" parts which sooooo many people enjoy. But that's a minor loss, really....

Re:If they think it's viable...

[goose-incarnated]

Let's try a novel approach to the problem.

1. If you don't want to go to Mars, don't.

2. If someone else does, it's their problem. They're not asking you to be their Mommy and tell them what's good (or bad) for them, anymore than you're asking them to be your Mommy....

Wait, what? You want to silence those who mock others? Did you even read your sig?

"I do not agree with what you say, but I will defend to the death your right to say it"

Are you using that quote sarcastically? Making fun of stupid people (flat-earthers, creationists, people who want to go to Mars, etc) is a time-honoured tradition.

Done. Problem solved.

And as an extra bonus (for one group or the other), someone will get to tell someone else "See!? I Told You So!"

So a win-win situation, in general. Yeah, you lose the "I told Wilbur and I told Orville that that thing would never fly" parts which sooooo many people enjoy.

You appear to be missing the fact that throughout human history, the majority of the people who said "that will never fly" were correct. They may have laughed at the Wright brothers, but they also laughed at Bozo the clown. Just because someone says that your idea is stupid, that does not automatically make your idea any better.

The majority of ideas called stupid are, in fact, stupid. A few gems turn out to be smart, but there are so few of them that they are dwarfed by the stupid ideas out there.

Re:If they think it's viable...

[amiga3D]

Ah, but without the risk there is no reward.

Re:If they think it's viable...

[goose-incarnated]

Ah, but without the risk there is no reward.

Yes, and we need people to take those risks. Doesn't mean we can't mock 'em :-)

Re:If they think it's viable...

[110010001000]

How about you stop wasting MY taxpayer money on this boondoggle and join us back on Earth? You aren't going to Mars. No one is.

Re:If they think it's viable...

[HangingChad]

How about you stop wasting MY taxpayer money on this boondoggle...

With that mindset we never would have had railroads or the interstate highway system. We all contribute and then make a collective decision about the best use of the money. I'm one of the people who votes we spend the money to go to Mars. Not because I benefit, but because we all benefit.

That's life in a democracy. If you don't like it, move.

Re:If they think it's viable...

[erapert]

1. If you don't want to go to Mars, don't.

I won't.

2. If someone else does, it's their problem. They're not asking you to be their Mommy and tell them what's good (or bad) for them, anymore than you're asking them to be your Mommy....

Then they can pay for it themselves and stop forcing me to pay taxes for it. So SpaceX gets my approval assuming they don't use government grants and contracts to pay for their endeavor. NASA gets my disapproval.

Re:If they think it's viable...

[david_thornley]

I can defend someone's right to say things and exercise my right to make fun of them. There's no inconsistency here.

Not only a travel problem

[manu0601]

Once travelers get to mars the problem is not over, as Mars magnetic field is rather weak, because its dynamo was killed a long time ago

Re:Not only a travel problem

[JDeane]

I think they did a movie about that "The Core" or something like that... I just remember it had an underground train with lots of nukes and huge diamonds, also it seemed to ignore pretty much everything I think I know about physics... lol

Fake Edit: ahh here it is lol https://en.wikipedia.org/wiki/...

Re:Not only a travel problem

[meta-monkey]

God that was a stupid movie. Fun, though, but very stupid. I think it had the best "monuments blowing up" scene for a disaster movie ever. The Coliseum gets struck by lightning a bunch of times, and as everyone knows, stone struck by lightning enough times explodes. And then later the hole in the ozone layer opens over San Francisco and causes the Golden Gate bridge to melt in seconds.

Re:Not only a travel problem

[Whatsmynickname]

Live underground, perhaps?

Re:Not only a travel problem

[Ungrounded Lightning]

Live underground, perhaps?The

Also, the atmosphere provides SOME help.

It's a serious issue for settlers, though, if they ever want to do stuff on the surface. While the trip to Mars might take years, for settlers, life on Mars would take the rest of their lives (as well as the entire lives of of the bulk of their descendants.)

Re:Not only a travel problem

[Ungrounded Lightning]

3. High-temperature superconducting Helmholtz coils around the planet at about the equivalent of the Arctic and Antarctic circles should do nicely, and take a LOT less energy and resources.

Shields up Scotty

[MxMatrix]

So it seems space travel needs an artificial magnetosphere on spaceships.

This study is garbage

[iris-n]

They didn't expose the rats to anything similar to the radiation an astronaut would be subjected to in their travel to Mars: they fried the rats with a short, intense radiation dose, while the astronauts would be exposed to a low dose long term. In fact, in the study they don't even claim that this radiation is anything similar to what one would find in space, they just say it is "space relevant". So what they found out is only that if you fry rats with radiation it impairs their cognition, and this impairment is long-lasting.

Also, TFS says that Scientific Reports is a Nature journal. This is true, Nature the company (or more precisely Holtzbrinck Publishing Group) does own this journal, but it has nothing to do with the Nature journal, editorially or scientifically. This is just a lame attempt to bestow Nature's reputation on Scientific Reports, which is in fact a pretty crappy journal, that does not even try to select papers based on quality, but claims to check only for correctness.

Re:This study is garbage

[Required Snark]

So you don't like the message? Shoot the messinger!

This experiment was motivated by observations about moon mission astronauts. It's not like someone with an anti-manned space agenda pulled it out of their ass as an excuse.

The astronaut data is not definitive. The experiment is not definitive. No one is going to send more people outside the van Allen belts to see if their brains and hearts rot. But they are going to do more definitive tests to find out what is going on. Lots of tests, some of which will take a long time. It's not like the first manned Mars mission is lifting off next week, there is plenty of time to do the fundamental science. That is how science works. Trash talking a study and a publisher won't change anything.

Maybe the effect is not that bad. Maybe shielding will work, either physical shielding or electromagnetic shielding. Maybe drugs will need to be developed. Until the prerequisite experiments are done, and the science understood, it's premature to invest a lot of effort in solutions.

It's not that much different then building the rockets or designing and deploying a Mars base. It's equally nerdy, just in a another direction. One without explosions or dealing with the environment on Mars.

So why so hostile? No one said this was a show stopper. For example, it would be completely normal if biotechnology was as important for interplanetary travel as rocket motors.

You are reacting like a spoiled brat. No one is taking away your toy. Grow up.

Re:This study is garbage

[iris-n]

You clearly haven't read either my comment or TFA itself. If you have a substantive criticism of my position I'll be happy to respond.

Re:This study is garbage

[michelcolman]

But why do they perform such an irrelevant experiment and then claim that it is "space relevant"? (Knowing full well how the media are going to interpret it). Oh wait, I guess I just answered my own question.

Would it be so hard to subject the rats to a longer duration, lower intensity dose that actually resembles the conditions on a space mission? Oooh, but then they might find less spectacular results and wouldn't get any media attention... I guess I just answered my own question again.

Next up: headline in all major newspapers, scientists prove that cell phones may make your head explode. Critic on Slashdot says they just subjected a mouse to a short energy burst equivalent to a trillion cell phones and therefore the explosion was to be expected and does not say anything about the safety of cell phones. Pedant responds that this was clearly stated in the original report by the scientists and therefore the critics have no right to point it out.

Re:This study is garbage

[110010001000]

So basically you are saying that the NASA people (who actually have been in space) did the basic key concept of their study wrong, and you (who have never been in space) figured it out.

Re:This study is garbage

[iris-n]

You are writing an ad hominen attack in response to a comment where I complain that Required Snark was not making any substantive criticism. Isn't the absurdity of this situation too much for you? How about you make, hummm, some... substantive criticism?

But to not leave you completely without response, what makes you think that the researchers who did this study are "NASA people" who "have been in space"? And if I were to take their study seriously, being in space leads to cognitive impairment, so people who have been to space would be more likely to get the key concept in their study wrong.

Re:This study is garbage

[110010001000]

It isn't an attack. It is just a comment. Basically you are saying that the NASA scientists (you can look at their bios) didn't consider the core concept of their study (the radiation blast wasn't anything like what you would get from travelling to Mars)? So do you think they are incompetent? What is your explanation?

Re:This study is garbage

[stealth_finger]

So basically you are saying that the NASA people (who actually have been in space) did the basic key concept of their study wrong, and you (who have never been in space) figured it out.

Space nutters, eh? Don't they know that you have it all figured out already and the conclusion is fuck space.

Re:This study is garbage

[avandesande]

They discovered a long time ago that there is no difference between short bursts and long term exposure...

Re:This study is garbage

[iris-n]

I'm not going to look for their bios, the onus of proof is on you. I have checked the affiliations listed in the paper, and they are oncologists from the University of California. But this doesn't matter at all, as the radiation dose used in the paper is not anything like the radiation from interplanetary space. This is a simple fact, that does not depend on whether the study was made by random potheads, oncologists, NASA scientists, or the second coming of Feynman himself. And you would know this if you would look at the paper itself, where they don't even claim that radiation is similar to what you would experience on a trip to Mars, but instead that they just subjected the rats to a short intense burst.

If you want me to speculate on why they studied the wrong kind of radiation, I can think of two reasons:
1 - It is hard to build a source of low-intensity radiation with similar characteristics to galactic cosmic rays and keep the rats exposed to it for six months.
2 - A given amount of radiation is much more damaging when delivered in a quick burst than when delivered slowly over a period of months. Therefore if they had done the study properly the effects would be much less dramatic, and the news wouldn't make it to the first page of Slashdot.

Re:This study is garbage

[iris-n]

This is simply not true. Short bursts are much more damaging. And since you're the one claiming there is no difference, the onus of proof is on you.

Re:This study is garbage

[waveclaw]

The study is actually important. They showed that the brains didn't recover from the damage as expected. The radiation treatment did not trigger the plastic repair behavior expected from an injured brain.

Yes, the particles used don't resemble background Solar radiation. It doesn't even resemble the stream of lightweight charged particles from a Coronal Mass ejection. However, the model is similar to the burst of Cosmic Background Radiation (CBR). Like the kind you get on an unplanned spacewalk to fix something on the outside of your spaceship. Or if your shielding fails.

It is very hard to make a usable spacesuit for a human that shields against individual sometimes neutral particles with the energy of a fastball thrown by a world record setting baseball pitcher. It is also hard to build a light enough and thick enough shield against CBR when your astronauts insist on hanging out on the edges of your rotating spacecraft to avoid losing bone mass.

This lack of repair response is the kind of thing you have to learn about to be a space faring species. It's the science part of science and engineering.

Fixing it is the engineering part. You'll have to use better shielding. Or you can genetically engineer people to trigger the plastic response to damage like Water Bears use. Or just make all repairs outside the CBR shielding involve robots and drones.

Re:This study is garbage

[iris-n]

I think you are confusing the very rare very energetic cosmic rays with the constant background of low energy cosmic rays you have in space. Nobody cares about the first kind, because they are so rare, the second is what worries people planning manned missions. Both are very tough to shield against, anyway.

And their radiation source is not similar to either kind. They just used some very radioactive isotopes to expose the rats to a nice bath of gamma rays and alpha particles for a few seconds. This is much less energetic than the cosmic rays of the first kind, but much more energetic than the cosmic rays of the second kind.

Re:This study is garbage

[Reziac]

The info I've paid attention to on long-term symptoms experienced by astronauts has all pointed at one thing: low-level thyroid damage, probably due to cosmic bombardment making some of the body's iodine radioactive (which in turn kills bits of the thyroid gland). Probably worth testing a protective "collar", as well as shielding stuff like iodized salt and seafood.

Turn space ship into large magnet

[bongey]

I am pretty sure the best solution is to mimic what already works. The space ship needs to be one giant magnet , which I think could be done without losing the space ship part.

That's something every nerd knows

[Exitar]

How do you think the Fantastic Four got their powers?

Re:That's something every nerd knows

[meta-monkey]

They got drunk and decided to test out their interdimensional transportation device and then the green ooze from the other dimension planet caused them. And the producers said "holy shit this movie sucks!" and rushed out an ending in 2 days and released it.

That's why you need deflectors

[m76]

I thought it was obvious that you need some sort of radiation shielding for interplanetary space travel.

Re:Doesn't make much difference

[michelcolman]

Would certainly make a great reality show...

Re:Turn space ship into large magnet

[michelcolman]

Sure, the booster can be reused a thousand times, so they should have no problem sending up lots of little magnets.

Re:Scanners Live in Vain

[harlequinn]

I.

Its the photons

[perpenso]

Actually I think that they figured out that magnetic fields involve an exchange of photons.

Re:Its the photons

[Rockoon]

Sure, it "involves an exchange of photons" .. that doesnt explain it tho

Re:Doesn't make much difference

[Rei]

It's even worse because there's potential compounding factors on Mars that could make psychological issues even worse. For example, here's one that's little studied: deuterium. Mars's deuterium levels are 5-7 times higher than Earth's (nothing like Venus's 150-240x, but still..). Animals and plants certainly can survive rather high deuterium levels, up to 50% (and bacteria can survive 98% deuterated water); in terms of survival, it poses no threat. However, in terms of effects on long-term health effects, it's much less clear. For example, one study found a 1,8% increase in incidence of depression for every 10ppm increase in deuterium in water (Earth mean = ~155ppm). So when you're talking an ~800ppm increase... the issue of long-term deuterium health effects really warrants more study. Furthermore, microbial food sources that may be used on Mars (either for direct consumption or producing feed for, e.g. aquaponics) can concentrate deuterium even further.

Unlike most isotopes, hydrogen isotopes have rather different properties. Deuterated drugs are a new field of interest, for example, as they can have lifetimes in the body an order of magnitude higher than their non-deuterated equivalents. Deuterated plastics are often dramatically more transparent (and significantly more radiation resistant) than non-deuterated plastics. However, mixtures of deuterated and non-deuterated versions of the same plastic, melted together, often yield an opaque result because the two versions have different melting points and densities, yielding an inhomogenous result.

Oh my beloved ice cream bar

[zifn4b]

Ren: You're not like the others, you like the same things I do. Wax Papers. Boiled football leather. DOG BREATH! We're not hitchhiking anymore. We're riding
Stimpy: Stop it. You're talking crazy.

Re:Oh my beloved ice cream bar

[Jon Abbott]

Indeed. This effect was described 25 years ago by John Kricfalusi and dubbed Space Madness.

Well...

[Eric Wayte]

...I guess we're stuck here.

It's not like there aren't solutions

[transami]

http://www.nasa.gov/feature/goddard/real-martians-how-to-protect-astronauts-from-space-radiation-on-mars

Re:Turn space ship into large magnet

[NotAPK]

I'm sorry, but you're the 4th or 5th poster to claim that a magnetic field will shield high energy cosmic rays and this assertion is wrong. You need *mass* to shield them, and on Earth that mass is provided by the atmosphere. Adding mass to spaceships compounds the fundamental problem we have with getting anywhere in the solar system, namely the "rocket equation".

There are some alternatives but they are all highly speculative.

Re:We are made of meat

[thinkwaitfast]

Meat?

Re:Um....

[Anonymous Coward]

>>because we *still* don't know how to grow anything on the moon
Actually ...
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0103138

I'm not saying it's a solved problem. I am saying you are exaggerating a bit.

Cosmic radiation may

[ElizabethGreene]

>> This summer a study showed the cosmic radiation may have damaged the hearts of many of the Apollo program astronauts. You lose some credibility saying this, IMHO. The Apollo program was wrapping up when I was born, and half of them can still fog a mirror.

Re:Cosmic radiation may

[rubycodez]

a person can't be living with a damaged heart? tens of thousands of morbidly obese slashdotters prove you wrong

Re:Um....

[Anonymous Coward]

As has been pointed out elsewhere, the article is clickbait nonsense, because the experiment was nothing like the actual conditions that Mars astronauts would experience. Secondly, "These people are going to starve to death long before they suffer the effects of radiation, because we *still* don't know how to grow anything on the moon, nor could they carry enough with them even if we did."? How do you figure this, exactly? Humans require about 1 ton of food per year, and about 70% of that weight is water, and we do have the technology to recycle water (with some wastage, so it won't last forever, but we can do it well enough that we can effectively multiply the amount of water we have 10X at least). So that would be .37 tons of food/water per astronaut, per year. So, for a ten year mission, 3.7 tons. For an entire lifetime (let's say 80 years), about 30 tons. Most of the food could be launched separately from the astronauts and landed on Mars with just a parachute (foil-packed,freeze dried food can hit the ground at hundreds of miles per hour without damage). Based on Falcon Heavy launch costs, a lifetime supply of food for one astronaut would cost about $250 million to deliver. In situ food growing would obviously be preferable, but clearly isn't necessary.

Re:Turn space ship into large magnet

[Anonymous Coward]

So question, obviously the ISS has magnetic shielding from earth but no mass shielding where we have had Scott Kelly for 12 months at once. Similar for MIR where an astronaut stayed for 14 months. Although perhaps high energy radiation from planet side would not hit so it would be reduced to say 1/2? Would this not be the same as if artificial magnetic shielding was added to the ITS? Obviously they monitored Scott Kellys health very closely and he was up there for double an expected Mars one way trip. I would have expected a pretty sensational media story if something was medically wrong with him by now.

Shield (+Meds)

[DrYak]

First, Rei, RealDrJohn, it's nice to see a good discussion between specialists (Still one of the reasons why I keep hanging out on /. )

I also think that hyper massive ships are a good solution.
More possibility for shielding.
More fuel, bigger drives to accelerate to a higher top speed (and then again to decelerate to target orbit at the other end of the trip).

Also it fits better the *current* development of SpaceX and space programs in general :
cheap recyclable launchers.

When you want to build a giant inter-planetary vessel, you won't launch it into one single go (not like the new reboot StarTrek's Enterprise) because you're going to get hit hard by the Tsiolkovsky rocket equation.
You'll launch it piece by piece and build the vessel in space (like the ship harbour of older movies, or like the real-world ISS).
See the recent explanation video by SpaceX, showing the capsule and the giant freaking fuel tank (which doubles as a nice shield) being launched in 2 separate steps and then assembled in orbit before leaving for Mars.

That means trying to achieve cheaper multiple-launches which is also what the current needs are (launching sattelites and probes cheaply, instead of send huge masses away), and also what SpaceX is researching (cheap re-usable launchers).

---

Also, maybe by then we will have some medical approach to try to shave a few % of the cancer risk.
Taking some meds maybe...
Maybe under some circumstances, special regiments rich in antioxydant could provably drop the cancer incidence and brain/heart damage in the radiation-exposed mices by 1-2% ?

Re:Shield (+Meds)

[Grishnakh]

You'll launch it piece by piece and build the vessel in space (like the ship harbour of older movies, or like the real-world ISS).

No, if you want to build real interplanetary vessels, you'll build them in space, not on the Earth. Lifting the entire mass of a ship from the Earth's solution isn't economical or practical; all the major building materials we need are already in space.

Re:Shield (+Meds)

[The Real Dr John]

The best options for now in my opinion are for people to stay in Earth orbit most of the time, and enjoy the nice magnetic bubble shield. Robots with telepresence can do the work further out until scientists and engineers get a handle on being in interplanetary space for long periods. For very long distance travel they really will need the spinning ring around a central core to provide artificial gravity, and that is going to make a big ship. Without the gravity people will lose bone and muscle mass even with various exercise regimes. We evolved with gravity as an essential aspect of life, and you really can't live properly without it. So for long distances and long flight times we need artificial gravity and full shielding in at least the parts of the ship where people spend their time. Dosimeters of some type will probably be useful.

Space refineries

[DrYak]

No, if you want to build real interplanetary vessels, you'll build them in space, not on the Earth. Lifting the entire mass of a ship from the Earth's solution isn't economical or practical; all the major building materials we need are already in space.

One day, we'll maybe be there (once we have enough ore refineries in orbit ?)
For now we're still stuck with our industry on Earth, but at least we can already displace the assembly in space.

(but once space assembly is doable, further down the line you can start assembling an industry in-space).

Re:Space refineries

[Grishnakh]

Yeah, but we'd be better off launching missions to sample asteroids and start developing the ability to capture them for resource extraction (and maybe also on the Moon if we can find useful materials there; this would probably require more probes as well). We need to do this *before* we get grand ideas about building giant spacecraft and sending manned missions to other planets, complete with habitats. These asteroids are buzzing right by us here on Earth; there's no excuse for ignoring them while trying to jump directly to what is really just a PR stunt. We already have rovers on Mars doing science work safely and remotely; it's a much better use of our space exploration dollars to develop resource-extraction capabilities in space near the Earth than to send humans to Mars at such an early stage.

faulty premise

[micahraleigh]

Increased brain activity increases anxiety.

E.g: frontal lobotomy patients act like children. Little to no anxiety.

Re:Doesn't make much difference

[Rei]

It's not a question of energy; it's a question of hardware. Distillation plants tend to be very large indeed.

That said, there is a good option for offworld use. Namely, unless your power source is nuclear, you need nighttime energy storage. Fuel cells tend to be a rather compact way to do this in comparison to batteries. In particular, since you're providing both oxidizer and fuel rather than using atmospheric oxygen, you can avoid the use of oxygen (and its high overpotential) and use, for example, a reversible HCl fuel cell. Regardless of what type of fuel cell you're using, during the daytime you're performing electrolysis, which has an extremely high enrichment factor (you can also likely get a good enrichment factor operating in galvanic mode, but this isn't as well studied). Hence, if your fuel cell layers are plumbed in a cascade (since every fuel cell stack needs numerous layers to reach distribution voltage regardless, so it's not hard to break them down into groupings of varying size), you can get enrichment for "free".

I do put "free" in quotes for two reasons. One, you still do have some mass penalty - extra hydrogen and HCl tankage (but not Cl2), extra plumbing, extra compressors/pumps, etc. The exact amount depends on the details of your setup. And two, the enrichment factor varies depending on your overpotential (ideally in terms of generation/storage the hydrogen side operates at almost no overpotential). If you operate at a low overpotential, you get better efficiency but reduced enrichment, while if you operate at high overpotential, it's reversed. But that said, it remains a viable option, and certainly is more realistic than, say, bringing a whole GS plant ;) And the "waste" (enriched) stream is certainly valuable. On Earth D2 goes for nearly $1k/kg. And locally it has applications in industry (esp. plastics), medicine, etc.

it's viable...

[mrchew1982]

"Wilbur and Orville didn't *talk* about building an airplane for the better part of a century while simply making more and more hype artwork and articles." Instead humanity dreamed about flying since we stepped out of our caves Milena ago. Seriously, Greek legends about Icarus, Renaissance artist's renditions of helicopters, etc etc. Humanity has always been obsessed with flying. I'm sorry that you don't want to travel to the stars, but humanity needs something to fix our collective eye on and work for, else we devolve into smacking each other over the head with clubs for breeding rights, food and water. If the technology doesn't exist to make it viable let's invent it. Apollo did wonders for our world, I expect that if humanity got its act together and started working on a shared goal we'd all be much better off. Living just to be comfortable doesn't sound like living to me.

Here's a Solution - -

[hduff]

They could wear tinfoil hats.

Re:Named user accounts frequently not better

[Grishnakh]

I agree about the growing science illiteracy on Slashdot, however I disagree about the specialness of named accounts. With a named account, when someone shows that they're some kind of fruitcake, I can put them in my "foes" list, and then they're automatically down-modded to oblivion so that I can't see their posts without specifically clicking on them, so I can easily ignore them. I could, of course, do this for ACs (I'm considering it...), as there is a setting for this, but I hate the idea of filtering out the useful AC comments that way. So I'd rather see them move to banning ACs and forcing interested posters to sign up for an account. I know it'd suck for people who just don't want to be bothered, or who are afraid of being connected to their real identity, but really it's a small thing to ask to be able to post on a web forum. Most places don't allow anonymous commenting any more anyway; just look at Reddit: there's no anonymous posting there, only pseudo-anonymous (but there, signing up for new accounts is quite a bit faster and easier than here, which leads to a lot of throwaway accounts). HN doesn't allow anonymous comments either.

Re:Turn space ship into large magnet

[NotAPK]

Read the rest of the Wikipedia page, it's really interesting stuff. You are correct, the ISS is protected by the Earth's magnetic field to some extent. There is an order of magnitude more radiation exposure from 6 months on the ISS than the US average. That figure estimates almost another order of magnitude of exposure from a 6 month Mars mission.

Re:Turn space ship into large magnet

[NotAPK]

PS: It's not my figure, but it needs to be interpreted correctly: the first "Mars" bar is for the 6 month transit to Mars. The second "Mars" bar is for 500 days on the surface, and you can see it's the same dose. So a "slow" (6-month transit, 500 day surface time) mission to Mars will accumulate three times the radiation exposure as shown on the Figure, which is almost exactly an order of magnitude more than 6 months on the ISS. I don't know what they didn't include the compound bar on the chart.

I doubt cognition is the real risk

[Chalnoth]

The effects of radiation in humans have been studied pretty extensively. People tend to have many severe health effects of other kinds long before cognition is impacted. We should be worrying about the astronauts dying long before we worry about them having reduced cognition.