Space Exploration

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

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

Matt Williams is a space journalist and science communicator for Universe Today and Interesting Engineering. He's also a science fiction author, podcaster (Stories from Space), and Taekwon-Do instructor who lives on Vancouver Island with his wife and family.

Recent Posts

New Horizons is Funded Through the Decade. Enough to Explore Another Kuiper Belt Object

The ongoing saga of the New Horizons mission—will it get truncated and its science team…

8 hours ago

It's Confirmed. M87's Black Hole is Actually Spinning

The supermassive black hole at the heart of M87 was the target of the Event…

16 hours ago

What’s the Link Between Gamma Ray Bursts and Supernovae? It Might Be Binary Stars

Gamma-ray bursts (GRBs) are some of the most violent events in the universe. Some have…

1 day ago

Astronomers are Working to Put a Radio Telescope on the Far Side of the Moon by 2025

Technicians at Berkeley Lab are building an experiment that will conduct radio astronomy on the…

1 day ago

Supernovae Struck the Earth 3 Million and 7 Million Years Ago

A recent study examines how the Earth was hit by blasts from supernovae (plural form…

2 days ago

The World's Largest Radio Telescope has Scanned Barnard's Star for Extraterrestrial Signals

Barnard's Star is the second closest star system to Earth, at a distance of 5.96…

2 days ago