How can we protect humans on Mars from radiation from solar storms?

[Admin]

As space agencies and private companies look toward sending human crews to Mars, they'll have to find ways to mitigate the dangers posed by high-energy radiation from solar storms.

How can we protect humans on Mars from radiation from solar storms? : Read more

 

[Coinneach]

You do wonder if settlers on Mars are going to spend a lot of time hiding from radiation.

Won't it also affect crops?

Maybe the farm chambers will have radiation proof shutters which can be quickly closed, but I can't think of what they'd be made of.

 

[billslugg]

Solar storms are only part of the problem. Galactic cosmic rays are far more powerful and are not stopped by heavy nuclei very well, they just bounce their way on through. It takes about 50 feet of rock to equal the protection given by our atmosphere, which is equivalent to 40 feet of water. Water is comprised of light nuclei which are more effective at stopping high energy particles.

No amount of any protective material that one could carry about with them, even at lesser gravity, will protect against cosmic rays. All you can do is to make sure you are spending most of your time underground and you monitor your total dose from being outdoors. Also consider the trip to Mars. There is no way to shield a spacecraft with protection in the form of mass. Only a magnetic field might help.

 

[Coinneach]

Thanks for your reply

I had read that water and polythene are the least bad materials for radiation protection. Something to do with the bound hydrogen.

Could a Martian colony be protected by an artificial, local magnetic field; or would that require phenomenal amounts of energy?

Sorry if that's a daft question. I'm out of my depth here.

 

[billslugg]

The lighter the nuclei, the more it recoils when hit by a massive particle. This is how energy is removed from the big particle. Hydrogen is best at slowing them down.

Using fields to protect has an inherent problem in that no energy is removed from the cosmic ray, the ray is simply deflected sideways. Someone else is going to get it. No arrangement of magnetic fields could protect a given volume from particles arriving from all directions. At each pole, the particles would simply spiral around the magnetic field lines and land at the poles unabated. This is not an option for cosmic rays.

 

[Coinneach]

Cheers!

In my next life I will study more physics.

 

[Unclear Engineer]

FWIW, we are talking about radiation from particles that have mass, such as electrons ("beta rays"), protons, helium nuclei ("alpha particles") and neutrons, which mainly transfer energy by giving it to whole atoms with "collisions. That is completely true for neutrons, because they have no net electric charge, so those are collisions with atomic nuclei. But for those other particles that do have a charge, they will interact with the electrons bound to atoms, kicking them off and "ionizing" the atoms. So, charged particles have a specific distance they can travel in specific materials, depending on the mass of the radiation particle and the density of electrons in the material. For instance, the low energy electrons (beta particles) released by Tritium (double- heavy hydrogen) are so low energy that they don't even penetrate human skin. But cosmic ray electrons have so much energy that they can go much deeper. And he more massive cosmic ray particles will even act like the CERN "atom smasher" and break apart the nuclei of atoms that they hit, making a splatter of all sorts of other particles.

On the other hand, very high energy photons (e.g., x-rays and gamma rays) that do not have "rest mass" interact (almost) exclusively with the electrons in shielding atoms, and it a probabilistic way, So, they don't have a specific finite range in shielding, but get absorbed by a fraction of what is remaining per unit distance in the shielding. So, heavy material like lead does provide the best shielding for photon type radiation.

When a solar flare occurs, the photon radiation gets to us without any significant warning time, because those photons travel at the same speed as the photons of visible light that our eyes can see and the radio waves that any instruments near the Sun can send us. But, the particle type radiation is much slower, taking days instead of minutes to get to us from the Sun. So, there is warning time for the particle radiation

How to use that info to best shield astronauts in-transit is what NASA is looking for ideas about.

 

[Coinneach]

You see these artists impressions of proposed early Mars settlements which look like a string of portacabins. It sounds as if anyone trying to live in these will soon end up looking like something out of a Ready Brek advert. ("Do you want your kids to glow in the dark?!")

Reality seems more likely to be a lead-lined underground bunker; except that there won't be any lead.

All in all, space travel clearly won't suit anyone who suffers from claustrophobia.

 

[billslugg]

The best way around the whole problem is to have sleeping/cooking/working quarters underground. No easily constructed surface habitat is going to be able to support the needed shielding on its roof. There needs to be an overburden of 40 feet of water, 53 feet of solid rock or 100 feet of loose soil, by my estimates.

 

[Pogo]

If they pick the right location to land, there should be plenty of water, just need sufficient energy to melt it. Maybe live in one of those lava tubes they’ve seen, build a big water tank overhead. Voila! Shielding. I’m sure it’s easier said than done.

 

[Classical Motion]

No matter where we go we need to learn to bore holes.

 

[billslugg]

A tunnel could be bored with a tiny machine, by itself, just monitored from Earth. It would be a wheeled robot which would simply ablade the rock with a big laser. It would cool and capture the vaporized rock dust and pile it outside for further use. It might take it a long time but it could be done before humans get there.