The Real Problem With a Human Trip to Mars: Radiation

By Eliza Strickland | September 17, 2009 3:02 pm

mars-orbitThe presidential panel that recently evaluated the U.S. plan for manned spaceflight declared that “Mars is the ultimate destination for human exploration,” but stressed the financial and technical difficulties that must be overcome before a boot can be planted on that red soil. Now, the New Scientist calls attention to the greatest technical hurdle: protecting astronauts from radiation during their trips to Mars.

The radiation comes in the form of cosmic rays, which are actually speeding protons and heavier atomic nuclei that rain onto our solar system from all directions. They can slice through DNA molecules when they pass through living cells and the resulting damage can lead to cancer [New Scientist]. The residents of Earth and the temporary lodgers at the International Space Station are protected from the rays by the Earth’s magnetic field, but astronauts heading to Mars would have no natural protection. Aluminum or plastic shielding on a spacecraft would have to be impractically thick to safeguard astronauts, and other solutions, like the creation of a miniature magnetic field around the spaceship, are still being developed.

Researchers say that a round-trip mission to Mars orbit (which would take about 750 days) could give astronauts a dose of radiation that’s four times more than the lifetime exposure limit spelled out in NASA’s safety rules. Still, the presidential panel didn’t rule out such missions, but instead asked NASA if it would consider simply accepting higher risks for the missions. Steven Lindsey, head of NASA’s astronaut office, thinks most astronauts would probably be open to the idea. “It depends on the individual,” he says. “I’ve got crew members that will fly on anything” [New Scientist].

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Image: NASA. Artist’s rendering of an experimental spacecraft in Mars orbit.

CATEGORIZED UNDER: Space, Technology
MORE ABOUT: cancer, Mars, space flight
  • Troy

    I would go! There’s no way you can take the risk out of something like this… but to be the first person (or persons) to step on Mars??? Sign me up!

  • Brian

    Didn’t I read, some years ago, that a Mission to Mars would require a substantial amount of water. There was a proposal to put this water in the walls of the spacecraft such that it surrounded the astronauts. That way you have a water container system doing double-duty as a radiation shield (come to think of it, it’s also a viable micrometeoroid shield).

    I don’t know if you can make it thick enough to make this workable. Also you have to wonder how complete the coverage can be (the doors and windows are likely to be challenging for sure). As a meteoroid shield you risk losing your water supply due to a strike, but it’s better than taking a hit directly to the occupants and I’m sure you can segment the containering system or take other mitigating steps.

  • Simon

    I’ve read enough Hugo winning stories to know that its the High Fast Fish that you really have to worry about.

  • Chrysoprase

    Wouldn’t advances in propulsion help with this problem? I seem to remember an article recently saying that advances in ion drives had made cut the theoretical travel time down significantly. Less time = less radiation.

  • John Wilkins

    The cost of getting water up there, and the propulsion mass involved in getting that mass to Mars, would be prohibitive. But then, if we could capture a comet, and set it in an orbit that crosses earth’s and Mars’ orbits, we could maybe just fly to the comet, insert the living quarters inside it, and detach when you get there…

  • Shaking head

    @ brian: 1 cubic meter/ m^2 is equal to one metric ton..if you were to use water as shielding you would simply not make it off the planet because we do not have a proplusion system that can carry that much weight. Not to mention that for the water shielding to work it must be 3 ft thick to successfully shield the astronauts.

  • scribbler

    There’s enough water on the moon…

    If it’s shielded from the sun, it would be a very cold ice and this should increase its efficasy…

    If the water and ship is put into orbit around the moon and the propulsion is done in stages, you could certainly get enough of it moving fast enough to make it to Mars. For that matter, you could blast the water free of the moons gravitational pull and then recapture it to make your shield.

    Factor in that escaping the moon’s orbit is roughly six times as easy as escaping the Earths, then even by conventional rockets, the trip to Mars is much more doable.

    Send your supplies and return vehicle ahead and then have them jump on it to come home…

    If you used even today’s ion drives and got the stuff accelerating on a path between the moon and Earth, say, and waited until it got to a speed where a conventionally fueled rocket could catch it, you could get it up to speed over months and then deposit the crew…

    This is why I personally believe that the first step into the rest of the solar system is the moon!

    As for exotic propulsion, if you set your sights on accelerating at one G, then ion drives don’t really have all that far to go. A one G acceleration then gives the same effect as conventional gravity on Earth and solves many problems involved with space.

    We can do this. It’s just a matter of being a little clever and spending time, money and effort now, for future endeavors.

  • Brian


    Re: “…at one G, then ion drives don’t really have all that far to go…”, I have doubts about this. All the ion drives I’ve heard about, that is built and successful, have paltry thrust values. Efficient yes, but powerful, no. Maybe it’s because they are new, or maybe the application didn’t require high power, but I suspect that it was more a case of making a virtue out of necessity.

    But I agree completely that the goal should be 1 G acceleration. Give that goal to the engine design teams and let them do their thing.

  • Brian

    @shaking head,

    OK, I can’t validate your numbers, but they seem reasonable enough. The one thing I’d say is that you don’t have to lift all your supplies off Earth in one go. In fact I’d seriously doubt anyone would try, not for a trip to Mars anyways. Once you think in terms of multiple supply lift missions new possibilities emerge.

    Also, while it would be ideal to have complete coverage, you might be able to cut shield coverage down a lot. If a major concern is radiation from the Sun (and I think it would be–for flares, CME’s and such), a large flat tank oriented sunwards would give partial coverage to the crew.

    I have to agree that accelerating all that mass towards Mars is going to be a big job. That’s where the rubber meets the road, so to speak!

  • Christina Viering

    Radiation is a bummer.

  • scribbler

    With the water on the moon and Mars, you can use electrolysis and break it down into hydrogen and oxygen which can then be used for conventional rocket fuel.

    As for the power of ion engines, my guess is that if you use nuclear reactors to generate the electricity, the thrust can be pushed up by a great deal.

    Catching comets? Why not? Still, I’d think that steering them into or into orbit around the moon would be both easier and safer.

    Pushing a huge block of ice ahead of the ship would act as a shield against particulates in space and wrapping the people in an ice envelope would protect them against radiation and micro meteors.

    Heck, as far as that goes, you could convert the ice into hydrogen and oxygen along the way and pour the hydrogen (and the oxygen too) into a reactor which would heat it and thrust it out the other side. The oxygen would be handy in many applications, I would think. Using such a model, acceleration at 1 G would be a breeze and I’m sure that a certain small but impressive percent of light speed could be reached…

  • seth

    Have a look at at vasimr and emdrives coupled to a small Sandia Gen 4 nuke. Trip would be damn fast.

    Convert the space station to a Vasimir powered slow boat space liner in a continuous Mars to Earth to Mars orbital path. Mars or Earth bound cargo or crew would match velocity in high power shuttle craft to catch the ride. Better still find a carbonaceous asteroid of a suitable size, and equip it as needs.

  • Shaking head

    @ brian: you are correct about multiple liftoffs being an option but, you are wrong of the origon of the radiation. It clearly states in the article that they are worried about cosmic rays with are created in supernovae ( giant star explosion and or implosion) and that they rain in from all sides off the solar system so a one sided shield would be no good. You need complete coverage of the astronauts for them to be safe, in literally tons of water.( metric tons which are slightly heavier than imperial tons) i personally think this will be a huge feat for humankind …if that is.. we can achive this goal before our ultimate self-destruction. Extinction.

  • Shaking head

    Not to mention the unearthly cost of doing all of this. I seriously doubt the human race will ever make it farther than the moon. Especially with all the funding getting cut off to nasa by the Americans’ president Obama.

  • Shaking head

    @ scribbler,
    An ion engine cannot take off from the ground. They are space based where you do not need a sufficient amount of thrust to gain lots of speed.

  • Frank Lipsky

    Re:Mars 1
    If you don’t have a good background in physics listen and LEARN FROM THOSE WHO DO
    2 If we can’t solve our energy shortage problems here on earth ;why would any one expect we can solve them anywhere in the universe ;let alone MARS?
    3 Unless and unless fantastic new sources of energy-mass are discovered humankind is stuck on the earth.Get over yourselves and the space lobbies!
    You will live here and die here unless you genetically re-engineered!
    4.Simple logic dictates we cannot get out off the earth in reasonable numbers and if someone can get here from out there they must be more intelligent (dangerous?)

  • Hmmm

    Shielding the passenger instead of the entire spacecraft might be more feasible.

    Perhaps the answer lies in genetic engineering like what Frank Lipsky said.

    Be it a biosuit or increased radiation resistance through genetic modification.

  • don

    plasma engine’s are being developed as we speak, meaning the trip would be 39 days. multiple launch point- the moon. as well as we would have to take the basic chemicals to produce 02, water ect… should be another 20 or so years, take for instance the fact that it was 65yrs after the Wright brothers flew that we reached the moon,so another 65yrs. is safe to assume that we will have advanced enough in science to make the trip happen.

  • amphiox

    I do not think we can build an ion engine with the kind of power necessary for what Scribbler has described, yet. And I am not certain if it is even possible for an ion engine to achieve that kind of power, as my understanding was that the high efficiency/low power tradeoff is inherent in the physics behind the engineering of the design of that type of engine.

    If we had an engine that could achieve continuous 1g acceleration for any length of time, such an engine would get us easily to mars in just a couple of weeks, a timespan during which radiation exposure shouldn’t be a problem. Such an engine would indeed get us pretty easily to almost any place in the solar system in very reasonable periods of time. If we had that engine, we’d have moon and Mars bases and Lagrange point colonies within a few years, in all likelihood.

    Frank Lipsky said: “Simple logic dictates we cannot get out off the earth in reasonable numbers”

    A reasonable number is only a couple hundred people or so, possibly split up into a few handfuls of 10s or 20s at a time. That’s all you need to establish a viable colony and allow for reasonable interchange of people and commerce. The rest of us who remain on earth will of course be responsible for keeping this planet an acceptable place to live, but the colony would be a nice insurance policy for the survival of the species if we should happen to fail.

    Granted the colony will take some time to become self-sufficient, and it won’t be a useful insurance policy until it gets to that point, and it is likely that at least some of the early colonies will fail, which is all the more reason to get going on this project.

    Genetic engineering will be a given, even if it just limited to sexual selection arising from local martian/lunar/whatever fads.

  • amphiox

    “a continuous Mars to Earth to Mars orbital path”

    Would such a orbit be stable? Each time it passes close to Earth or Mars its going to get its orbit gravitationally tweaked. If we’re going to use an asteroid of any substantial side we’re talking about a roughly biannual near-collision with an NEO.

    We’d probably want to stick with smaller asteroids. It’ll have to have engines of its own for the necessary orbital corrections.

    Perhaps it would be better if the asteroid cycled between gravitationally stable points far away from Earth and Mars, but from which a spacecraft could be launched to reach Earth and Mars with minimal energy expenditure.

  • scribbler

    Asteroids would, to me, prolly be better mined for there resources than used as space craft but then, they could be hollowed out and have a thruster shoved on them and they would work…

    I’m more for ice since it’s easier to obtain and manage…

    The thrust on ion systems now is limited by the amount of electrical charge that can be generated. Use a nuke reactor and you have plenty of power…

    The thrusters of even today put out about enough thrust to push a single piece of paper. If all you push is one piece of paper, they can get them up to speed mighty quickly. The reason it takes so long to get a ship up to speed is that it is many, many kilos and though the paper page thrust will move it, it will not move it to speed very quickly. The only reason to use them at all is that they will accelerate up to the speed of the particle being ejected, given enough time.

    So, even with this puny thruster, if you use a reactor, you can power literally THOUSANDS of them. This then gives you a thrust factor of thousands of pages…

    So, if, again, you set your sights on 1 G with a nuke for power, Mars (and yes, just about anywhere else in the solar system) gets doable with an ion thruster.

    Even without a nuke, you can use an unmanned ion thruster over even years to get a payload up to speed and then hop aboard with conventional chemical rockets.

    If you ram gases through a reactor, you’re limit then becomes the amount of material you can turn into gas. Yet, with even a smallish reactor you can get an enormous thrust return and it again, gets doable.

    As for time factors using a 1 G acceleration model, don’t forget that you spend half the trip accelerating at 1 G and the other half decelerating as 1 G…

    We all agree that this will take enormous amounts of money and effort which to me then raises the most insurmountable obstacle to Mars: What’s in it for us?


  • Shaking head

    The chance to say we colonized another planet.. How many other animals on earth could say they did that… None.. We don’t know if anything else has done it period.

  • http://none Mauric

    In my humble opinion, mankind is on self destruct mission and may be it is what is intended for the human race!! Otherwise, leaving well enough alone as nature intended might have saved humanity a great deal of agony. Endless pursuit of knowledge is unstoppable and has its consequences – good, bad and ugly.

  • http://none Mauric

    In my humble opinion, mankind is on self destruct mission and may be it is what is intended for the human race!! Otherwise, leaving well enough alone as nature intended might have saved humanity a great deal of agony. Endless pursuit of knowledge is unstoppable and has its consequences – good, bad and ugly.

  • Chris

    Wouldn’t be nice to know that you were able to prevent that to make just enough of a change to keep the human race going. Why would you want to just keep driving down the road and crash into the ravine when you could have stopped and took the detour that lead away from it. Sure the pursuit of knowledge has its consequences but you never know if you don’t try.

    The pursuit of knowledge is all that we have to look forward to as the human race. Why would we stop when it has already done us so much good. Healthcare and Medicine for example. If people didn’t try anything for the knowledge there would be no vaccines, and a lower age limit (people dieing younger). If you think about it if no-one ever tried the pursuit of knowledge there would have never been an evolution in the way of life it would be exactly like the cavemen all you can do is hope to survive.

    I personally think being able to live on the moon or mars would be an amazing idea. This would be exactly like the 1500s when we discover the “New World” but this time it really would be a new world.

  • Ron Bennett

    The whole thing about the radiation exposure is way out of line, it could be easily managed with current technology. A simple magnetic plasma bubble that NASA has been testing for years would protect the astronauts from most radiation on its trip to Mars, add a radiation compartment completely surrounded by water as proposed by some researchers to stop the fast and slow solar neutrons then you would have a very safe journey.

    The NASA estimate for the whole trip to Mars and back, 750 days in space and on Mars is a bit too long for the initial journey anyway. They could use Nuclear propulsion that would cut down their travel time to Mars at about 60 days which would give them 90 days on Mars before they had to return to earth which now would take another 75 days, so the round trip would be around 225 days drastically cutting down the astronauts exposure to radiation. Nuclear propulsion technology isn’t nothing new, NASA has been testing these types of advance technology for 55 years, the nuclear reactor can be activated in space and tethered way behind the mother spacecraft to reduce the amount of exposure they would get from that.

  • fb36

    I think we better wait at least a few more decades before attempting to go to Mars.
    Because w/ current tech it would be really hard to do and extremely expensive.

    We still need some critical new tech. like all electric drive, a (true) oxygen generator, better water recycling tech, magnetic shield against cosmic rays etc.

  • amphiox

    Mauric, the pursuit of knowledge began when the first proto-australopithecine looked down from the trees and wondered if there was anything good to eat down there on the grass, and decided to climb down and find out.

    It is the defining characteristic of the human lineage. Nature “intended” us to be slow, small-toothed, weak-muscled, blunt-nailed, meaty and juicy critters, but with a big brain with the capacity to pursue knowledge and use it to exploit the environment in order to survive. What would we be if we deny that last part of our natural heritage? Cat food.

  • Markus Demetrius

    I’d bet these technical problems would be solved quickly if the USA took just a tenth of it’s defense budget and spent it on basic research. Sure as hell would boost the economy.

    1. Why the hell does America need 11 aircraft carriers when no other nation has more than 2? Just how many countries do we have bases and/or troops in? Eisenhower was correct when he made that statement about how our military-industrial complex was too powerful for our own good.

    2. Why Mars? Just another short-term goal, like going to the moon was 40 years ago, although no one could argue it didn’t pay for itself many times over. Mars won’t give us much of a payback because it’s actually not much of a challenge, given our current technology level. The moons of Jupiter and Saturn are much more promising targets, and since they’re more difficult to achieve they’d provide many more spinoffs to our economy than a Mars mission. I challenge the first sentence of the story – “The presidential panel that recently evaluated the U.S. plan for manned spaceflight declared that ‘Mars is the ultimate destination for human exploration.” Why not espouse a philosophy of setting VERY difficult goals for our space program, and then fund it properly, so that our technology, economy and standard of living continue to advance?

    3. Take another tenth or so of that defense budget and make college free to anyone with a 3.0 grade average. Education is the cure for superstition. It’s the superstitious (religious) among us that are the ones who always fall for the fear-mongering tactics of the big corporations/Republicans. How many hundreds of years has superstition stalled science?

    Thanks to decades of opposition by Republicans and their Christian supporters global warming may actually have reached the tipping point – humanity’s time might be over (relatively) soon. If we’re to survive as a species we’d better start spending our money and resources on research instead of bombs and aircraft carriers. We may be wrong about climate change, but scientists around the world say it’s coming. Republicans and Christians are willing to gamble with our childrens’ future – that says volumes about their supposed moral superiority.

    I’m not saying that all Republicans are Christians, or that all Christians are Republicans – but the majority are, both ways. Evil is Evil, whether carrying a Bible or M16. I say this as a retired US Army soldier who loves his country but hates what its become – the bully of the planet.

    China is ahead of schedule in it’s 50 year plan. America never plans more than a decade ahead, and even those plans are timid, as accommodations must always be made for the average voter who happens to be uneducated. Stop allowing our kids to drop out of high school and give them free college. Raise the intelligence level of the average American. Our time may well be limited, and our pattern of short-term thinking is guaranteed to decrease whatever time we may have left.


  • Markus Demetrius

    Oops, I’ve proposed even longer trips and rad exposure times. Hmm, actually investing in research instead of guns would, in a matter of years, expand our space toolkit of ideas so much that rad exposure prevention might seem trivial compared to other solutions we’d come up with.

    Put a temporary hold on investing in research for radiation shielding and all other space research, instead go all out Manhattan Project or Apollo Project-style on propulsion technologies. The benefit of this long-term approach is that you’ll get more of a payback. Yes, it’ll probably take longer to produce tangible results, but faster and faster propulsion should be our main push because advances there will open up the entire Sol solar system to manned flight. Faster vehicles would also just plain make us think bigger, aim higher than simply planting a flag on the rock next door.

    Correction to previous post (29): may be misread as saying our loyal Troops are evil. Should read: Evil is Evil, whether carrying a Bible or starting wars – and if you don’t think Christianity is Evil then you know nothing of history or of the millions of people who’d been praying for the biblical Armageddon to occur in their lifetime but are now co-opting climate change as part of God’s Plan. They’ve co-opted Xmas and Easter, believe me when I say they’ve gotten quite good at the subtle methods of holding onto power over the past few millenia. ALL religions, not just Christianity, are Evil. Christianity just happens to have the worst track record.


  • Shaking head

    I agree with markus completely..

  • Hammers and Rakes

    So many tools posting, I feel like I am in an internet hardware store! If we faked the moon launch, how much of our money will be absconded for the fictitious trip to Mars?

    We have uncharted ocean depths, undersides of polar ice to explore, Rain forest secrets to reveal- before they are gone. Keep your fatuous sci-fi fencing to the teenie chat rooms you all usually cruise.

  • Markus Demetrius

    Hammers and Rakes – You should visit this site, it’s right up your alley:


  • Biggles

    Hi all, lets face the music shall we, the proposed return to the moon is proving very difficult despite over 40 yrs of advances in almost every field!

    The chances of making a manned mission to Mars this side of 2050 are very very slim.

    A successful moonbase should be tested first, thats about as likely as us getting back to the within the proposed decade – thats very very very unlikely at present.

    Costs are immaterial if the mission is a serious proposal, the good researched technology is not there to create a modern moon mission, it is possible only if the will is there, political posturing only agitates the problems. space exploration is a long term investment of peoples time, industries research & development , plus government and populace backing!!!

    Unless military black budget advances in recent years are released to shortcut some of these serious issues – then we have have a damp squib for a moon mission.
    Attempting a NASA Manned Mars Landing is many decades away either way.

    I would not be surprised if the military do not want anyone to return to the moon anytime in the near future – I think we all know why !

  • Markus Demetrius

    Biggles – Why?

  • Mkeller

    Why do we need to send people to Mars as a first step?

    Everything that we can possibly want to know about Mars as well as to bring back from Mars can be done with robotics. For the price of sending several humans to Mars (at a great risk of radiation poisoning) we could send several hundred remote controlled robotic rovers to Mars to scout out huge areas and possibly bring back fairly large amounts of minerals back to earth for analysis. Finally these advanced robotic surveys could provide us with locations where we could place equipment and powersources that could be used by possible far future travelers….

  • Markus Demetrius

    I agree with Mkeller – no human flights unil we actually have promising targets. Work SMART, not fast.

  • Fill

    It would be pretty huge if there was water on the Moon. It would mean rocket fuel could be produced there (hydrogen and oxygen from breaking apart the water by using solar energy).

    The big problem is budget. NASA’s is pathetic compared to, say, the national defense budget. I think I read it was less than 1% of the defense budget? For example, the New Horizons mission to Pluto costs about 1/4th of a single B-2 stealth bomber.

  • Markus Demitrius

    Fill – As long as America is a Christian Nation we will spend the vast bulk of our tax dollars on WAR and only a fraction of it on SCIENCE. Religion is ultimately about DEATH and it’s followers hate KNOWLEDGE.

    Why does America have eleven aircraft carriers when no other nation has more than two?


    Who are they?


    What are they?


  • Frank Lipsky

    This is to add clarity to my post 16 above.
    My complaint about the foolishness of manned exploration was directed at scientists and professors
    who are silent about the economics of manned spaced missions.That silence is partially caused due to the financial benefits they gain from government/industry grants; however my judgment can be labelled subjective!
    Here are some facts
    Factoid1:The two fundamental laws of physics are the same throughout the know universe ;e.g. Eisntein’s Theory of General Relatavity (Macroparticles )and Quantum Mechanic(micro particles)
    Factoid 2 Mass(man -equipment) can never travel anywhere near the velocity light c-it is a law a physics ;so the fastest sources of information are light sources (stars) gathered by Hubble telescope and radiotelescopes and analyzed by humans-not human space travel!!
    Factoid 3 the Mars Rovers and the Moon landings were interesting but produced no major discovery.Why ?Refer to Factoid 1
    Conclusion Most manned exploration is a waste of money and intellectual resources .Example name one major success of the manned spaced station other than the repair of Hubble telescope?


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