Cancer Risk for a Human Mars Mission Just Got a Lot Worse

Article written: 7 Jun , 2017
Updated: 8 Jun , 2017
by

Astronauts hoping to take part in a crewed mission to Mars might want to pack some additional rad tablets! Long before NASA announced their proposal for a “Journey to Mars“, which envisions putting boots on the Red Planet by the 2030s, mission planners have been aware that one of the greatest risks for such a mission has to do with the threat posed by cosmic and solar radiation.

But according to a new study from the University of Nevada, Las Vegas, this threat is even worse than previously thought. Using a predictive model, this study indicates that astronauts that are the surface of Mars for extended periods of time could experience cell damage from cosmic rays, and that this damage will extend to other healthy cells – effectively doubling the risk of cancer!

The study, which was led by UNLV scientist Dr. Francis Cucinotta, was published in the May issue of Scientific Reports – under the title of Non-Targeted Effects Models Predict Significantly Higher Mars Mission Cancer Risk than Targeted Effects Models“. Building on conventional models that predict that DNA damage caused by radiation leads to cancer, their model looked at how such damage could spread throughout the body.

At one time, Mars had a magnetic field similar to Earth, which prevented its atmosphere from being stripped away. Credit: NASA

Galactic cosmic rays (GCRs) are one of the greatest hazards posed by space exploration. These particles, which originate from beyond our Solar System, are basically atomic nuclei that have been stripped of their surrounding electrons, thanks to their high-speed journey through space. In the cases of iron and titanium atoms, these have been known to cause heavy damage to cells because of their very high rates of ionization.

Here on Earth, we are protected from these rays and other sources of radiation thanks to our protective magnetosphere. But with missions that would take astronauts well beyond Earth, they become a much greater threat. And given the long-term nature of a mission to Mars, mitigation procedures and shielding are being investigated quite thoroughly. As Cucinotta explained in a UNLV press statement:

“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 heavy ions are unavoidable. Current levels of radiation shielding would, at best, modestly decrease the exposure risks.”

Previous studies have indicated that the effects of prolonged exposure to cosmic rays include cancer, central nervous system effects, cataracts, circulatory diseases and acute radiation syndromes. However, until now, the damage these rays cause was thought to be confined to those cells that they actually traverse – which was based on models that deal with the targeted effects of radiation. 

Artist’s impression of astronauts exploring the surface of Mars. Credit: NASA/JSC/Pat Rawlings, SAIC

For the sake of their study, Dr. Cucinotta and Dr. Eliedonna Cacao (a Chemical Engineer at UNLV) consulted the mouse Harderian gland tumor experiment. This is the only extensive data-set to date that deals with the non-targeted effects (NTEs) of radiation for a variety of particles. Using this model, they tracked the effects of chronic exposure to GCRs, and determined that the risks would be twice as high as those predicted by targeted effects models.

“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 cells to mutate, thereby causing additional tumors or cancers.”

Naturally, any indication that there could be an elevated risk calls for additional research. As Cucinotta and Cacao indicated in their study, “The scarcity of data with animal models for tissues that dominate human radiation cancer risk, including lung, colon, breast, liver, and stomach, suggest that studies of NTEs in other tissues are urgently needed prior to long-term space missions outside the protection of the Earth’s geomagnetic sphere.”

These studies will of course need to happen before any long-term space missions are mounted beyond Earth’s magnetosphere. In addition, the findings also raise undeniable ethical issues, such as whether or not these risks could (or should) be waived by space agencies and astronauts. If in fact we cannot mitigate or protect against the hazards associated with long-term missions, is it even right to ask or allow astronauts to take part in them?

In the meantime, NASA may want to have another look at the mission components for the Journey to Mars, and maybe contemplate adding an additional layer or two of lead shielding. Better to be prepared for the worst, right?

Further Reading: UNLV, Nature

Matt Williams is the Curator of Universe Today’s Guide to Space. He is also a freelance writer, a science fiction author and a Taekwon-Do instructor. He lives with his family on Vancouver Island in beautiful British Columbia.

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7 Responses

  1. Member
    stuartajc says

    “In the cases of as iron and titanium atoms, these have been known to cause heavily damage to cells because of their very high rates of ionization.”

    Good article, spoiled by a bit of sloppy writing.

    “of as” ?
    “cause heavily damage” ?

    • Pvt.Pantzov says

      Don’t sweat it too hard. It’s classic Matt Williams. More importantly, this is yet another reminder of how fragile we are. Space (or planets with weak magnetospheres) is not a place that we were meant to be and if that is ever to change, we will need significant improvements in tech.

    • bazbsg says

      Agreed

  2. cferonberg says

    This would be a great article if the grammar was fixed.

  3. ProfMOZ says

    Not really any news… we knew all this for a very long time. No protective atmosphere, no magnetic shield… bla bla
    Such articles serve only one purpose. to slow down development. If we don’t go to Mars, we don’t have to face the problems associated with such an endeavor…
    Best is to stay below ground at home, and wrap ourselves in aluminum foil!
    We have to tackle the problems while we’re at it, and SOLVE them. Otherwise we all die on earth, from those problems described plus those created by us.
    I’ll go anyway 😉

    • Member

      No, such articles serve to raise awareness of the actual challenges we will face. Certainly that is important if we actually intend to send people or let volunteers go, hmm? Also, we did not know, prior to this study, that damage caused by cosmic rays could extend to healthy cells.

      • gopher65 says

        This is exactly the reason why no one plans to have a habitat on the surface of Mars. All plans call for either underground dwellings, habitats on the surfaced that are then buried in a couple meters of regolith, or putting habitats inside shielded lava tubes.

        Literally no one wants to do what this article is built upon. This is a classic example of the Strawman Logical Fallacy.

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