NASA/JPL-Caltech/Univ. of Arizona

Elon Musk dreams of creating a million-person city on Mars. But first, the SpaceX and Tesla founder is going to need a small group of people with an unusual genetic trait in common; resistance to radiation.

Radiation resistance in humans and animals is something we know little about, although we know it exists. At the moment, resistance tests are used to try and predict how much radiation cancer patients can survive, but one day this could be an important decider of who gets to venture into space.


Our Earth is protected from the harmful radiation from the Sun by our magnetic field, but astronauts that leave the planet will be bombarded with the dangerous particles.

Norman Kleiman, from Columbia University's Mailman School of Public Health, has spent his career using eyes as a way to study the effects of exposure to radiation. We know more about individuals, human or animals, that have genetic defects in certain genes or groups of genes and therefore exhibit radiosensitivity, than those who are more resistant to the effects of radiation, he explains.

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However, it's not impossible that in the future, humans could be gene-edited to better withstand the harshness of space; not limited to the radiation. There are many other new factors people will have to cope with when venturing to space, and we might be able to achieve those using gene editing.

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“Gene editing can build a new type of innate, biological defense for astronauts on long-duration missions, along with physical, electrical, and pharmacological methods for protecting them,” says professor Christopher Mason, from Weill Cornell Medicine.

“Gene editing done in organisms like plants and bacteria so that they better survive non-native environments would certainly help space-faring humans by constructing familiar habitats and providing sustainable sources of food and medicine,” says Lisa Nip, from the Massachusetts Institute of Technology. Its a promising field of research, but a breakthrough remains a long way off.

“Gene editing in living humans, on the other hand, is still in its infancy,” says Nip. “There hasn't been much in the way of human trials to demonstrate that gene editing is indisputably effective or safe, not to mention the ethical questions that come into play once human gene editing is scientifically validated in human trials.”

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There are a number of ways researchers are looking into protecting humans from the effects of radiation.


“Melanin in humans helps to dampen the effect of UV radiation from the Sun, but some of the radiation in space can't really be tackled simply by amplifying melanin production in the skin,” Nip explains. “Cosmic rays are higher in energy than UV, so such melanin-producing genes may help a little, but not by much, especially if the exposure is constant like it is in space.”

This could be one of the routes we go down to prepare humans for long-term space exploration. “Such research could, in theory, help make humans more radiation-resistant, but it will be a long way off from making humans radiation-proof,” Nip adds.

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Another route could be found by looking into our eyes.

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The lenses in our eyes are one of the most sensitive parts of the body when it comes to exposure to radiation. Astronauts, who are exposed to dangerous levels of space radiation, and survivors of atomic bombs and accidents such as Chernobyl, have been shown to be much more susceptible to a condition called radiation cataracts.

This special type of cataract, which was seen for the first time in a rabbit in 1897, is easy to detect because it grows from the back of the lens. Exactly what causes it is unknown, but the current best explanation is that it forms because of DNA damage.

In a paper published last year, Kleiman and colleagues the Netherlands Cancer Institute identified a class of ‘radioprotector’ molecules, which are much more effective in much smaller doses than anything used before.

However, this research is also in its infancy, and Kleiman says more work needs to be done on the topic before we can properly understand what makes some humans more prone to suffering from the effects of radiation than others.


If radiation-resistant humans are sent to Mars, this would make an interesting pot of humans from which new traits could evolve separately from those on Earth.

“Within the first generation they would be evolving, and since they would be under such strong constraints in terms of radiation they might evolve to be more radiation-resistant” says Mason. “But the gravity is lower there, so their bones would likely become less dense, they might be taller, and they would adapt to some of the differences in soil and atmosphere.”

There will be different, more short-term adaptive responses too, adds Nip, like how you adapt to a cold swimming pool after a few minutes in it. “But whether or not these short-term adaptations take a few years, decades, or millennia to be passed down to the next generation of humans is anyone's guess right now,” he says.