Elon Musk
Scientist Scott Solomon believes that humans could reach Mars within 10 years. However, creating entire self-sustainable cities on the Moon or Mars is still a big challenge.
It’s an old debate in space circles: humanity’s first city on another world should be built on the Moon or Mars?
Until last year, SpaceX founder Elon Musk considered missions to the Moon a “distraction”. In a post on his social media platform, SpaceX, he stated: “Let’s go directly to Mars“.
But last week, Musk said he changed his mind: “For those who don’t know, the SpaceX has already changed focus for building a self-sustainable city on the Moon, as we can potentially achieve this in less than 10 years, while Mars would take more than 20 years,” he wrote in SpaceX.
How realistic is either option, particularly over a 10 to 20 year time frame? In a new book titled “Becoming Martian,” Rice University evolutionary biologist, Scott Solomonexposes the possibilities as well as the dangers that could make Musk’s job more challenging than he imagines.
“The more I researched the subject, the more laboratories I visited, the more articles I read and the more experts I talked to, the clearer it became to me that we had considerable gaps in our knowledge and our understanding of what reality would be like”, says Solomon in the latest episode of the Fiction Science podcast.
It is true that humans have been traveling to space for 65 years and an entire library has been researched on the effects of space flights on health. But there have been very few opportunities to study what prolonged exposure to the space environment does to the human body. One of the most ambitious projects focused on how 340 days on the International Space Stationbetween 2015 and 2016, affected NASA astronaut Scott Kelly, who wrote the foreword to “Becoming Martian”.
“Long duration space flights take their toll, physically and psychologically“, acknowledges Kelly in his preface. One of the biggest concerns has to do with space radiation. Kelly’s level of exposure caused small mutations in his chromosomes, but colonists living on the surface of the Moon or Mars would face much more serious levels of exposure.
Extraterrestrial city planners could deal with the radiation problem by placing their populations in habitats protected by a thick layer of soil or built inside a lava tube. Solomon notes that in ancient times, thousands of people inhabited an underground city near the present-day Turkish city of Derinkuyu. But these residents managed to get out of their holes and circling the surface — an option that would be potentially dangerous for colonists on the Moon or Mars.
“I really don’t want to go to Mars if you always have to stay underground”says Solomon. “It would be a huge disappointment to get to Mars and not be able to explore the surface.”
Would it be possible for space colonists to modify the Martian environment to the make it more like Earth? In the book, Solomon describes the possibilities of terraforming Mars and concludes that “it would be an uphill battle, requiring constant maintenance.”
Provide food and water to extraterrestrial inhabitants would be another great challenge. Although the surfaces of the Moon and Mars are extremely dry and cold, both environments appear to have enough ice reserves to support settlements. But the colonists would likely have to grow their own food instead of relying on shipments from Earth. And they would probably have to discard the idea of taking animals.
“I suggest that we consider do not take animals with usspecifically mammals and birds”, says Solomon. He gives two reasons: firstly, these animals would compete with the colonists for scarce resources. “Perhaps the most practical way to create a settlement on Mars would be for everyone to be vegan”, he says.
Animals could also represent a threat to public health. “Most of the infectious diseases we face… come from infections that once affected animals, and then changed hosts and started infecting humans,” says Solomon. “If we left Earth and chose not to take birds and mammals with us, we could minimize the chances of new infectious diseases emerging.”
Humans will not be the only creatures living in extraterrestrial cities. Each colonist will carry trillions of gut microbes that play an essential role in human health. Gut microbiomes can even be genetically modified to perform optimally in the space environment. “We know that these microbes evolve in the same way that any of us will evolve when we leave Earth,” says Solomon.
How can humans evolve
In the book, Solomon deeply explores how life in Space will change the human species. For example, the inhabitants of extraterrestrial cities could evolve to become more tolerant to space radiation. Some researchers are even talking about using genetic engineering to give humans a greater ability to resist radiation damage to DNA.
“They have already had success, for example, in extract genes from tardigradeswhich are notoriously very resilient and even able to tolerate some of the conditions in Space,” Solom said. “They can take some of the genes that help tardigrades do this and implant them into human cells grown in vitro… and those human cells will express the same proteins that tardigrades use to suppress radiation damage.”
Another concern concerns the bone density. Over the years, studies have shown that astronauts tend to lose bone mass in microgravity, and it’s possible that people who get used to the reduced-gravity environment on the Moon or Mars have thinner and weaker bones than their earthly ancestors.
This could be a big problem for the second generation of an extraterrestrial city. “By the time a woman reaches childbearing age, her bones are already considerably weaker than they would be on Earth,” says Solomon. “And that’s when childbirth becomes a much riskier prospect.”
Solomon believes the safest way to give birth on Mars will be by cesarean section — which would have implications for future generations in these alien cities. “It means the head is no longer limited by the need to pass through the vaginal canal,” he says. “This has been a limitation that has existed throughout human evolution, and even before. So, if the head is no longer limited, it can get bigger. We can even imagine a scenario in which Martians have bigger heads… Then it starts to look a little more like science fiction depictions of aliens.”
People who grow up in the reduced gravity of the Moon or Mars may find it difficult, if not impossible, to spend an extended period of time returning to Earth. The issue of the microbiome may also contribute to the fragmentation of the human species, says Solomon.
“If I return to Earth, the microbes on Earth will be dangerous to you“, he says. “I think this is a potential challenge of an interplanetary future. If we want people to live on different planets, they may not be able to move easily between these planets due to the risk of disease.”
Why do this?
Considering all the challenges, is it worth taking the risk of building a city on the Moon or Mars? Solomon states that the risks are not as high for lunar colonization as for Martian colonization, mainly because it would be easier to travel frequently between Earth and the Moon. This is one of the reasons why, at least for now, the Moon surpasses Mars.
The potential for trade between Earth and the Moon is an important factor behind interest in lunar colonization. Commercial ventures, including Seattle-based Interlune, are already looking for ways to extract helium-3 and other resources from lunar soil and send them back to Earth. And Musk had another business idea: building a mass launcher on the Moon to catapult satellites into space.
“I can’t imagine anything more epic than a mass launcher on the Moon, a self-sustaining city on the Moon, and then going beyond the Moon to Mars, all the way through our Solar System, and finally being out there among the stars,” Musk said at an xAI all-hands meeting.
Anyone who has read Robert Heinlein’s classic science fiction novel, “The Moon is a Cruel Mistress“, you know that a lunar mass launcher can also be used as a deadly weapon. This brings us to another motivation for missions to the Moon: geopolitics.
NASA Administrator Jared Isaacman mentioned the space race between the US and China last year during his second Senate confirmation hearing. “This is not the time for delay, but for action, because if we fall behind, if we make a mistake, we can never reach China’s level againand the consequences could alter the balance of power here on Earth,” said Isaacman.
Solomon notes that the link between geopolitics and the space program goes back decades, to the space race between the US and the Soviet Union in the 1960s. “I would say I want to make sure that if we are moving quickly, regardless of the motivations, we continue to give priority to human well-being — and we don’t put people in danger just to get there first,” he says. So what will it be? A city on the Moon? A city on Mars? Or neither? Solomon believes it’s possible to have troops on lunar soil within a few years and on Mars within a decade. But that’s different from building a self-sustaining city.
“I hope that we are not very close to building a city seriously on the Moon or Mars, because I worry about what would happen to the kids who would have to live in that city,” Solomon says. “If adults are willing to take the risks of going to work there and spending as much time as they want, that’s fine… But I have serious concerns about the idea of taking a child to that environment, especially if there’s a possibility that that child could never return to Earth — which I think is possible.”
