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Poop shield could protect Mars space tourists

The interplanetary tourists who aim to fly by Mars on a private space mission may be protected from dangerous cosmic rays by a poop shield.

Taber MacCallum, part of the team planning the Mars mission, which is partially funded by the multimillionaire Dennis Tito, recently told the New Scientist about the gross-but-practical plan.

"It's a little queasy sounding, but there's no place for that material to go, and it makes great radiation shielding," McCallum told the magazine.

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Cosmic rays, radiation that travels throughout the universe and is caused by exploding stars, are a major source of danger for astronauts.

But human waste is an excellent shield, MacCallum said, so it makes sense to dehydrate the material and lay it against the walls of the space capsule as protection.

Because space is so precious aboard the flight, the system would line the walls with water bags that would be replaced with waste bags as the water is used. 

Food could also be a source of protection and serve to block cosmic rays.

But as the New Scientist reports, details of the plan remain to be ironed out: when a system that dehydrates waste was tested on the last space shuttle flight, it didn't work as well in microgravity as was hoped.

The proposed mission wouldn't launch until January 2018; the couple would fly by Mars in August, and spend 16 months total in space. 

Kate Allen is the Star's science and technology reporter. Find her on Twitter at @katecallen.


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If they intend the water in those bags to be drank or used, won't that water become irradiated and therefore be hazardous?

Lots of technical challenges to overcome for this trip! It'll be interesting to see what they come up with!

Water exposed to cosmic radiation would not become irratiated.

Cosmic radiation is actually not particulate-based (i.e., not particle decay from a radioactive substance like uranium, etc,), but rather electromagnetic (e.g., waves of energy) in nature.

Think of cosmic rays as an "extreme" X-ray.

Electromagnetic radiation cannot "irradiate" other substances; instead, if the "wave" is fast enough, what it does is potentially damage cells/molecules by knocking out electrons from their orbits (which we call "ionizing"). It's dangerous to humans because damaged living cells can lead to cancer.

But while "particle"-based radiation can actually leave a "deposit" of a radioactive particle when it comes into contact with a non-radioactive substance, electromagnetic radiation will either pass through the substance or hit/bounce off of it. If it hits something, the damage is a one-time thing -- just like if I threw a baseball at you and hit your arm. The baseball doesn't stay on your arm, but the damage from the hit (transfer of kinetic energy from ball to arm) will remain, and a bruise will form.

Throw enough baseballs at the same spot, and chances are you can eventually make that arm fall right off.

So, long story short -- water exposed to cosmic radiation would not become irratiated.

Hope that helps!

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