Study: Collateral damage from cosmic rays increases cancer risks for Mars astronauts

June 5, 2017 by Kevin Dunegan, University of Nevada, Las Vegas
Credit: CC0 Public Domain

The cancer risk for a human mission to Mars has effectively doubled following a UNLV study predicting a dramatic increase in the disease for astronauts traveling to the red planet or on long-term missions outside the protection of Earth's magnetic field.

The findings appeared in the May issue of Scientific Reports and were presented by UNLV scientist Francis Cucinotta, a leading scholar on radiation and space physics.

Previous studies have shown the health risks from galactic cosmic ray exposure to astronauts include , central nervous system effects, cataracts, circulatory diseases and acute radiation syndromes. Cosmic rays, such as iron and titanium atoms, heavily damage the cells they traverse because of their very high rates of ionization.

Conventional risk models used by NASA and others assume DNA damage and mutation are the cause of radiation cancers. This is based on studies at high doses where all cells are traversed by heavy ions one or more times within much shorter-time periods than will occur during space missions.

"Exploring Mars will require missions of 900 days or longer and includes more than one year in deep space where exposures to all energies of galactic cosmic ray are unavoidable," Cucinotta explained. "Current levels of radiation shielding would, at best, modestly decrease the exposure risks."

In these new findings, a non-targeted effect —where arises in bystander cells close to heavily damaged cells—is shown to lead to a two-fold or more increase in cancer risk compared to the conventional risk model for a Mars .

"Galactic cosmic ray exposure can devastate a cell's nucleus and cause mutations that can result in cancers," Cucinotta explained. "We learned the damaged cells send signals to the surrounding, unaffected cells and likely modify the tissues' microenvironments. Those signals seem to inspire the healthy to mutate, thereby causing additional tumors or cancers."

Cucinotta said the findings show a tremendous need for additional studies focused on cosmic ray exposures to tissues that dominate human cancer risks, and that these should begin prior to long-term space missions outside the Earth's geomagnetic sphere.

"Non-Targeted Effects Models Predict Significantly Higher Mars Mission Cancer Risk than Targeted Effects Models," appeared online May 12 in the journal Scientific Reports

Explore further: Research uncovers potential health risks of travel to Mars

More information: Francis A. Cucinotta et al, Non-Targeted Effects Models Predict Significantly Higher Mars Mission Cancer Risk than Targeted Effects Models, Scientific Reports (2017). DOI: 10.1038/s41598-017-02087-3

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eachus
4 / 5 (1) Jun 05, 2017
There are two (relatively) safe ways to get to Mars. The first is to go very fast, and we don't know how to do that. The other is to pick an asteroid that will pass near Earth, then near Mars. Send robots to explore, and if it is a good candidate, dig a hole.

When the asteroid passes near Earth the astronauts can board, and use the mass of the asteroid to cut down the radiation. A nice side effect is that if there is water, CO2 or other CHON compounds present, they can be converted into fuel for the Mars landing.

As for the way home, if you planned to spend over an Earth year on Mars, you could pick up the same asteroid for the return trip. Or use a new asteroid. But IMNSHO, a asteroid converted into a spaceship is worth holding onto. The asteroid could be worth more than all the science from the mission. Steering the asteroid can be done by burning fuel deep in the gravity well of Earth or Mars. Hmmm. Maybe the best choice is a short-period asteroid.
Parsec
not rated yet Jun 05, 2017
Actually, these studies are quite valuable to show what cells are damaged and by how much.

I believe one possibly acceptable approach would be to use drugs that cause cells that have been moderately damaged to destroy themselves at increased rates. While this will increase the short term effects of radiation exposure, such an approach could be used to mitigate accumulated damage effects leading to cancer and the like.

It is quite likely that as long as cells are actually destroyed and absorbed by the body, they will be replaced as a normal consequence of human healing with new healthy ones as long as the radiation isn't too intense. Its an open question if brain cells will be as easily replaced as in most other organs, but that's what research is for, after all.
ShotmanMaslo
1 / 5 (1) Jun 06, 2017
Artificial magnetosphere (nuclear powered superconducting coils?) may be required for long term stays in deep space.
antialias_physorg
5 / 5 (1) Jun 06, 2017
There are two (relatively) safe ways to get to Mars. The first is to go very fast, and we don't know how to do that. The other is to pick an asteroid that will pass near Earth, then near Mars. Send robots to explore, and if it is a good candidate, dig a hole.

The second idea has the same problem. To put such an asteroid into orbit you have to slow it down (impart a lot of additional impulse). Then you have to reaccelerate it to get it to Mars.

A way to manufacture shielding would be to go via the Moon and print a shell out of lunar dust
https://phys.org/...als.html

Taking off from the Moon is also a lot less energy intensive.

I believe one possibly acceptable approach would be to use drugs that cause cells that have been moderately damaged to destroy themselves at increased rates.
That would effectively aggravate radiation sickness.
baudrunner
not rated yet Jun 09, 2017
Here's a link to a refutation of this paper titled "Radiation Hucksters Strike Again", by Robert Zubrin, Mars Society President..: http://mailchi.mp...75b22de2

Given that cataracts are a far more serious issue in space than they are here, it follows that the absence of the Earth's magnetic field and atmosphere will play into a greater risk of cancers out there.

However, there's good science and there's bad science, and there are people down here who, for some reason or other, don't want us to venture into space. Of course, they come from out of the same box as those who don't want us to contaminate space. Really..? Plan on taking a walk in space without an overcoat any time soon?
jonesdave
not rated yet Jun 09, 2017

However, there's good science and there's bad science, and there are people down here who, for some reason or other, don't want us to venture into space. Of course, they come from out of the same box as those who don't want us to contaminate space. Really..? Plan on taking a walk in space without an overcoat any time soon?


I don't see any reference to not wanting people to go into space in that paper. It seems to be a reasonable study to assess the risks, prior to any long exposure mission. I'm sure NASA will take it on board (pun not intended), and assess it in a rational manner. TBH Zubrin is a bit of a cheerleader for Mars exploration, but wouldn't be the one taking the flak if Mars Astronauts started dying young some time in the future, due to NASA not fully assessing the possible risks.

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