Will we genetically modify astronauts to reach the Moon and Mars?

A few days ago, humanity returned to the Moon fifty years later and broke the record for the longest crewed journey into space. NASA's Artemis II mission successfully took four astronauts, three men and one woman, to the far side of our satellite. The next major milestone will be a new human landing, which, if all goes as planned, will take place at the beginning of 2028. From that moment on, with missions every six months, a permanent lunar base will be built, which should be completed around 2029-2030.

The conquest of the Moon will be joined by that of Mars. Several space agencies have announced that they have plans to send crewed missions there and at some point, also, to establish permanent habitable human communities.

For this to really happen, one of the main challenges we will have to face and resolve is human fragility. In deep space we face very high doses of highly energetic cosmic radiation, which shatters our DNA and causes cancer and neurodegenerative diseases, among an endless number of health problems. In fact, being continuously exposed to these ultra-energetic rays, such as alpha or gamma, seriously endangers life.

“We will reach the Moon or Mars, but living there will not be feasible, at least in the short term”, assures Aleix Bayona, head of the cancer biology and chromatin laboratory at the Faculty of Biology of the University of Barcelona (UB), and an expert in chromosomal instability.

“Cosmic radiation will literally fry the DNA of our cells and there are already scientific articles that have shown that this will cause an increase in cancer and neurodegeneration in astronauts”, adds Gemma Marfany, a genetics professor also from the UB Gemma Marfany.On Earth –and even a little on the International Space Station– the magnetosphere and atmosphere act as protective shields and largely prevent this DNA breakdown. Furthermore, the cells of the organism have repair mechanisms. In space, however, continuously exposed to radiation, they would be unable to repair the damage.

For this reason, some scientists, like Bayona, already defend: "We must look for mechanisms that allow astronauts to survive or adapt to these hostile environments." And they put forward an option: genetic modification.

Editing the genome to make humans more resistant

“We could edit the genome of astronauts or transfer genes from other organisms to them, like tardigrades, which are microscopic creatures highly resistant to radiation”, points out this researcher. And Marfany elaborates: “The only way to survive in space is external protection or increasing DNA repair mechanisms within each of our body's cells. And this could only be done with genetic editing in embryos”.

These ideas align with what Christopher Mason, a professor and researcher at Weill Cornell University in the US, who has worked with NASA to assess the impact of space travel on astronaut health, advocates for. One of the most famous scientific studies he has participated in is that of the twin brothers, both astronauts, Mark and Scott Kelly. One of them, Scott, spent a year on the International Space Station, and upon his return, scientists were able to compare what had happened to the genes of both. In a controversial book, and based on the results of studying the twins, Mason argued that humans need to be improved, made into a new species adapted to the hostile conditions of space. This would involve editing embryos to achieve generations of radiation-resistant humans.

 “In Europe and other countries around the world, for now, genetic editing on human embryos is totally prohibited”, emphasizes Marfany, who is also an expert in bioethics. Furthermore, she points out, this modification would not be therapeutic, but rather to improve human genetics. And this, for now, is not acceptable. At least in the West. “Other Asian countries are not so categorical and consider genetic editing in embryos potentially feasible”, she notes.

In fact, there have already been cases in China of embryo modification. And this Asian power competes with the United States in the space race to see which of the two will first establish itself on the Moon and exploit its resources. “It's not a question of if we can modify ourselves, but how we will do it”, Mason argues.

Heritable modifications

With this premise of how to modify humans to survive on Mars and the Moon, the UB research group led by Bayona will participate in iGEM, an international interuniversity competition, the most important in the world, focused on synthetic biology and which will be held in Paris this year.

“We will explore human genetic editing by incorporating genes from tardigrades, and also from planarians and axolotls, which have a very high cell regeneration capacity. We will see if embryonically this modification could be transmitted to all cells of the organism and if they would be heritable, thinking about future human colonies on the red planet”, explains to l’ARA this researcher who, in his laboratory, precisely investigates the accumulation of damage in the genome in the context of cancer, in which genomic instability, such as that caused by space radiation, plays a key role in tumor development.

“We will evaluate if a genetic screening of astronaut candidates could be carried out to determine who has a higher genomic predisposition to suffer problems from radiation, and who, on the other hand, has more resistance. And we will investigate biomaterials that work by absorbing radiation and attenuating the genomic impact”, he summarizes.

Modifying astronauts to confer them protection to go and live in space currently opens a Pandora's box, bioethically speaking. Marfany recalls that we do not know what effect the mutations we add to the human genome could have in the long term. “Heritable genetic editing in humans collides with all conventional bioethical principles of “maleficence”, “beneficence”, “justice”, and “personal autonomy”. Although, he acknowledges, “it could be that what now seems unacceptable to us, in less than twenty years, seems reasonable to us in some circumstances, for example, to generate humans who can travel to space for extended periods”.