A mission to Mars will benefit from a mini-magnetosphere (NASA)

Radiation Sickness, Cellular Damage and Increased Cancer Risk for Long-term Missions to Mars

Article Updated: 24 Dec , 2015

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There is a nagging problem under the surface of the excitement surrounding the future of long-term missions into space. Human exposure to the high amounts of solar radiation and other sources of cosmic rays is likely to be the main factor that could curtail mankind’s dreams for future manned settlements on other planets. The effects of radiation exposure to astronauts is not fully understood, but could range from acute radiation sickness (perhaps after being caught in an intense solar storm during interplanetary transit) to gradual cellular damage, greatly increasing the risk of cancer in long-term missions. So what can we do about it? Mankind is highly adaptive and some countermeasures are gradually being realized. (And yes, the Russian Space Monkeys might be able to help…)

The problem comes when humans leave the protective blanket of the Earth’s magnetic field. Acting like a huge, invisible force field, the magnetosphere deflects most of the harmful high energy particles being fired from the Sun. Anything that penetrates this barrier is quickly absorbed by our thick atmosphere. Even at high altitudes, in low Earth orbit, some protection to astronauts can be provided (although the ambient radiation is far higher up there than down here). So when we talk about colonizing other planets and sending astronauts further and further into deep space, radiation exposure becomes a bigger risk.

Solar flares will be a problem for future colonists (SOHO/EIT)

An immediate concern is that astronauts may get caught in a solar storm, where the Sun (usually around solar maximum) ejects huge clouds of highly energetic protons. If the storm is intense enough, huge doses of radiation could be inflicted on the men and women in space. Roughly, a dose of 500 rads or more will kill a human in two to three hours, and a smaller dose could cause acute radiation sickness. Radiation sickness could be fatal in weeks should the astronaut not receive urgent medical care. How about the long-term, gradual impact of prolonged exposure to higher-than-normal doses of radiation? This is an area of space medicine that we do not completely understand as yet.

In new research by the Lombardi Comprehensive Cancer Center at Georgetown University Medical Center, the high-energy nature of radiation in space may lead to premature aging and prolonged oxidative stress in cells. This also suggests that astronauts risk a higher than normal risk of cancers, such as colon cancer, through exposure to “high linear energy transfer” (LET) radiation. LET radiation consists of the high energy protons emitted by the Sun and cause a huge amount of damage to small areas of tissue.

Radiation exposure, either intentional or accidental, is inevitable during our lifetimes, but with plans for a mission to Mars, we need to understand more about the nature of radiation in space. There is currently no conclusive information for estimating the risk that astronauts may experience.” – Kamal Datta, M.D., assistant professor at Lombardi and lead author.

With NASA’s Project Constellation on the horizon, there has been a focus on the long-term effects of interplanetary radiation. Ultimately, this project aims to send humans to the Moon and Mars, but there are strong indicators that astronauts will face in increased cancer risk and lifespan reduction, a massive hindrance to a mission spanning several months or a thriving proto-settlement.

This is where the lab mice help us out. The amount of “free radicals” (highly reactive molecules often linked with cancer and cell aging) were measured and found that the mice developed highly oxidative (i.e. full of free radical molecules) gastrointestinal tracts when exposed to space-like high-LET radiation. The Lombardi group concluded that the mice had developed a high risk to various cancers, particularly gastrointestinal cancers. They also noticed that after exposure (even after two months), the mice prematurely aged, signifying that the effect of radiation damage can persist long after exposure to a high-LET environment.

So what can we do? There are several plans in motion to further test the effects of radiation on humans and to predict when astronauts will be at risk. This week, Russia announced (controversial) plans to send monkeys back into space, possibly as far as Mars. Once the shock of this “outdated” proposal wore off (the previous Russian space monkey program ran out of funding in the 1990’s), it became very clear as to what the Russian space agency is hoping to achieve: to have a better understanding of the long-term exposure to a high-LET environment on the human physiology. Many will argue that this practice is cruel and unnecessary, but others will say monkeys are used in experiments every day, why shouldn’t they help us in the ultra-modern world of space travel? The jury is still out on this debate, but there are many ways to investigate and counteract the radiation effect on humans.

Energetic particle tracks in a bubble chamber (NASA)

There are also many systems in place to protect mankind from the onslaught of solar storms. Using the Solar and Heliospheric Observatory (SOHO) and other craft located between the Earth and Sun, an early warning system has been set up to provide astronauts on orbit with some time to take cover should a solar flare be launched Earth-bound. This system is fully operational and has already proven itself. Recently, I toyed with the idea of a similar Mars-based early warning system, providing future Mars colonies with about 40 minutes advanced notice of an incoming solar storm.

Shielding is another obvious protective measure. Lunar and Mars colonies are most likely going to use large amounts of regolith to block the incoming particles. Only a few meters of locally dug-up regolith will provide excellent protection. But what about the journey to Mars? How will the astronauts of projects such as Constellation be protected? Perhaps an advanced “Ion Shield” might work?

Whatever the effect of radiation on humans in space, it seems obvious that we are in the infancy of space flight and we are already addressing some of the most difficult problems. Over the next few years, much effort will be focused on the health of astronauts, hopefully finding some answers to the space radiation problem.

Original source: Georgetown University Medical Center


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www.actionforspace.com
Guest
April 16, 2008 9:06 AM

Forget sending Monkeys to Mars. Send humans from the get go. It is so politically unacceptable to put humans life in danger in such a high profile venture, but it wasts money and time unnecessarily. Going to mars isn’t supposed to be a walk in the park, and this venture, as in all of the great exploratory movements of the past, will turn up plenty of qualified people willing to risk a 10-20% increased risk of Cancer.

Spoodle58
Member
April 16, 2008 11:55 AM

Case studys have already shown an extra 1% increase in radiation exposure as to what we get on earth by going to Mars. (see Case For Mars, By R. Zubrin)

This radiation ‘problem’ is just more time wasting nonsense.

In terms of risk, anyone going there would gladly accept any risk, for example in everyday life, I accept the risk when I cross a street that a car may hit me.
But that does not stop me crossing the street, why should the risk of radiation stop us going to Mars?

Its about time mankind and their repective goverments ‘grow a pair’ and go to Mars.

Spoodle58
Member
April 16, 2008 1:21 PM
“I have more concern for the psychological problems facing us humans after many months in space.” In answer to that one Ian, man has endured worst. Zubrin probably said this also in one of his papers or books. It took half a year to sail to Australia from Europe when Europeans where settling there, and in worst conditions than in a space craft, thats about the time it would take to get to Mars presently. Also many people have survived wars without seeing home for years and not even spoke to loved ones and receiving nothing but terrible conditions as well as the enemy looking to kill you. At least on the way to Mars they can comunicate… Read more »
MrBill
Guest
MrBill
April 16, 2008 3:32 PM

I’m with cheech on this one.

100% opposed to manned (or monkey) space flight.

From Someone
Guest
From Someone
April 16, 2008 10:33 AM

Very interesting.But wait humans already went to the Moon…. or THEY DID NOT.

Richard Kirk
Member
Richard Kirk
April 16, 2008 10:45 AM
If you try and stop high energy protons with conventional shielding, you risk creating a shower of other more strongly ionizing particles and making things worse. The ion shield might be a solution. However, a simpler solution might be to have a plastic low-Z shield on the sun side of the living quarters. The protons would be coming from the sun. Compton scattering would send them off in some other direction. The sun only subtends half a degree, so we would have to make the thing about 1 cm larger for every 1 m it is behind the living quarters. Make it 1 m larger and stick it 100 on the sun side of the living quarters, and… Read more »
tacitus
Member
April 16, 2008 11:47 AM

We certainly have to fully solve this problem before space travel beyond Earth’s orbit becomes commonplace. Until then, as a previous commenter says, there will be a level of risk that is acceptable to the astronauts and the taxpaying public. If offered the chance to be one of the first people on Mars at the possible cost of five years of life-expectancy (ignoring the danger of not coming back at all) then I would be willing to bet that the vast majority of the qualified people would jump at the chance.

leafguy
Member
April 16, 2008 12:42 PM

I don’t think i is exactly 1%, had heard it was at least that and possibly .5% higher in some quotes. However, I don’t think the increased cancer rate is a big deal given the ever increasing rates of it here on earth. The biggest problem is the lack of treatment available to them.

cheech
Guest
cheech
April 16, 2008 3:26 PM

whatever

David R.
Member
David R.
April 16, 2008 4:41 PM

Opponents to manned space flight underestimate the “imagination factor.” Photos sent from the lunar surface captured the attention and imagination of nearly two generations. Similar phenomena happened when colonists sent back reports about a “New World.” We need a spark to provide a long term commitment of resources and agenda to space exploration. I don’t think there would be any shortage of people willing to subject their bodies to radiation in exchange to the among the first to set foot on new soil…

Jorge
Guest
April 16, 2008 5:06 PM
OK, I get the thrill, I get the imagination factor, I get all the politics behind such an undertaking (if the kind of politics pushing it is the right one, at least), I get all that, but I still think it’s early to seriously think about putting humans on Mars. We need a lot more experience in Earth orbit first, we need to have a presence in space that is quite a bit more routinary than the one we have now, we need to perfect the techniques to build and repair in micro and low gravity, which means we may need a moon base before we go to Mars. AND we need to explore the planet a whole… Read more »
agesilaus
Member
agesilaus
April 16, 2008 5:25 PM

I believe your numbers are off, 5000 rad will be lethal in hours. 500 rads, rapidly delivered, is fatal to some of the population but only after a long course of radiation sickness.

Spoodle58
Member
April 17, 2008 1:28 AM

If humans didn’t go and explore themselves most of the people leaving comments here would be doing so from Europe and not from America.

We’d still be in the dark ages huddled together in dark box.

Its in our nature to explore and to do it ourselves.

Joel Raupe
Guest
Joel Raupe
April 16, 2008 11:33 PM
Having approached the report from the National Academy in Washington with skepticism, after finishing their latest report, I’ve concluded it is not, as I’d believed, simply JPL budgetary propaganda. The Academy spelled out knowledge gaps, for example, and was more than useful and certainly a scholarly and serious work. Among their many conclusions is that we do not yet have sufficient shielding from Galactic Cosmic Rays, particularly from the heaviest and most energetic nucleons, Lunar travel, the Board concluded also, fell well within the 3 percent probablity of REID (Radiation Exposure Induced Death) but all estimates of missions to Mars fell outside this minimum probability that stands as a proven standard for NASA safety protocols, particularly for what… Read more »
FrankG99
Member
FrankG99
April 16, 2008 9:46 PM
I expect, in the next decades, we’ll go to Mars on a 6 month ballistic trajectory just to do it. It will be on the razor’s edge of our technology, much like Apollo, and we may or may not get there and return much like the engineering gamble that was Apollo. While Apollo only had to keep all the technology running perfectly for 2 weeks or so, a mission to Mars is an engineering nightmare because we’re looking at 2 years of perfection for a Mars mission. One hiccup and it could be all over. Apollo 13 illustrated all to well how close to failure each mission to the moon actually was. More than radiation (though not to… Read more »
Polaris93
Member
April 17, 2008 8:46 AM
Mr. LAME
Guest
Mr. LAME
April 17, 2008 2:15 AM

ok . sooo
moon mission is all fake smile
oh…you bastard , ian !!!

PHWilson
Guest
PHWilson
April 17, 2008 5:27 AM

The answer will probably be a radically adapted outer skin of carbon fiber, just as a stealth plane uses. The internal sandwiching construction actually refracts/radiates the probe impulse around the craft to see the empty sky on the other side.

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