If you've been paying attention lately, you've probably heard about the Denis Villeneuve adaptation of Frank Herbert's Dune, which is set to open in the US on October 22.
The film, like the book before it, is almost entirely set on the desert planet Arrakis, which is in a remote, inhospitable part of a sprawling, universe-spanning human empire.
An otherwise unremarkable planet, Arrakis is home to gigantic sandworms who excrete a substance known as the spice melange that makes faster than light travel possible, along with several physiological benefits like prolonged lifespan and parapsychological abilities like prophecy.
Naturally, this makes Arrakis a hotly contested planet among the political factions of the empire. These Great Houses vie for the chance to administer the planet's government and manufacture the lucrative substance for the empire — and take a healthy cut of that wealth for themselves — by bringing in heavy industry on a massive scale to keep an intergalactic empire running smoothly.
This conflict sits at the heart of Dune's story and its setting makes for one of the most fascinating worlds ever constructed in science fiction and one which has begged the question since the book's initial 1965 publication: Could humanity not just survive on a planet so devoid of water, but actually thrive in its absence?
The Geology of Dune's desert world Arrakis
Like most arid environments, the first thing to note is that Dune's Arrakis isn't completely lacking in water. Some limited oases exist at the planet's poles and deep within the mountains jutting up out of the desert.
The in-universe explanation for the lack of water on Arrakis is that the enormous sandworms, during their larval sandtrout stage, encysted all of the planet's water over a period of many millions of years, during their metamorphosis into adult sandworms.
This turned what was once a wet, lush planet into a barren wasteland of sand, dust, and the occasional rock outcropping that hasn't been sandblasted flat by the relentless march of time.
This isn't as unbelievable as it might appear at first blush, both in terms of the sandworms as well as their capacity to change the entire environment of the planet. For the latter case, human activity has been radically changing the climate of the planet over the course of a fraction of that same timescale, with our most dramatic impact occurring in just the last 500 years.
As for the sandworms, there are definitely enormous by any modern standard we could apply to an animal, with the books putting them at as long as 450 to 1,000 meters long and able to survive for millennia.
Again, this might seem farfetched (and it definitely is), but it's not as if Earth wasn't once populated with megafauna as recently as 65 million years ago. Certainly, nothing on Earth existed on the scale of Dune's sandworms, but biology — especially alien biology that might not operate under the same rules as our own — could allow for something as gargantuan as a kilometer long sandworm to exist.
As for age, we have living things on this planet that are thousands of years old, most notably trees. The oldest known tree, the Great Basin Bristlecone Pine, is estimated to be more than 5,000 years old.
Dune's anaerobic sandworms are also responsible for producing the oxygen in the planet's atmosphere, similar to the way cyanobacteria produced Earth's oxygen atmosphere over the course of about a billion years, starting around 2.45 billion years ago.
This last part is at least a boon for would-be settlers of Arrakis, like the book's protagonistic House Atreides, who at least would have an atmosphere that they could breathe.
In terms of weather, without an active water cycle, the only weather of any importance would be the enormous sandstorms akin to those we've seen on Mars, like the one that finally disabled NASA's Opportunity rover in June 2018 and which feature heavily in the narrative of the first book.
Unlike Mars though, Arrakis isn't a frigid wasteland, but rather a properly scorching hot desert more akin to the Sahara desert or the desert of the Arabian Peninsula (which served as inspiration for Dune in more ways than just its setting).
It isn't completely inhospitable to human life, however, and upwards of 10 million semi-indigenous Fremen bedouins live in the deserts of Arrakis while another 5 million live in the capital city Arrakeen, located at the north pole of the planet, where the climate is milder.
So how realistic is it for human beings to live on a planet like Arrakis, especially since it is such an obvious analog for the possible colonization of Mars in the future?
What It Would Take for Humans to Live on a planet like Dune's Arrakis
So even though Dune is one of the greatest works of science fiction of the 20th century, and the new movie by nearly all accounts is shaping up to be a blockbuster, how realistic is it for humans to live on a world with so little water?
First, we should take a look at how the humans in Dune manage to survive and, in the case of the Fremen, actually thrive on the planet.
The first thing to note is that while incredibly scarce, water isn't nonexistent on Arrakis. The humans on Arrakis in Dune live where the water is, much the same way humans on Earth do.
While "civilized" society lives in the polar capital of Arrakeen, where water isn't plentiful but is at least easier to access, the more nomadic Fremen tribes out in the desert congregate in and around mountain outcroppings where underground sources of water can be found. Few people, if anyone, lives out the desert proper, just as no one lives out in the middle of the Sahara Desert, even if they have to travel across it occasionally.
This is perfectly feasible since it's something we see here on Earth all the time. Humans have lived in the deserts of the world for millennia just fine by doing as the humans of Dune do; they stick to those rare places in the desert where water is at least accessible, if not plentiful.
Another source of water for the people of Arrakis is to literally suck the water out of the air mechanically. Using windtraps, the Fremen extract what moisture there is in the air as part of their survival strategy. Physically, this is a perfectly sound strategy, though it isn't likely to yield enough water to sustain anyone on its own.
But an important element of Fremen culture is the conservation of water by any means necessary, so this little bit of moisture pulled from the air adds something to the reservoir, so to speak, and every little bit of water is valuable.
This kind of cultural adaptation to scarcity is well within human experience, as many indigenous peoples around the world have long cultural histories around the responsible stewardship of resources. While something like the harsh environment of Arrakis might push human adaptation to the extreme, humanity has survived all manner of hardships, including at least one Ice Age, and come out the other side just fine.
One particular adaptation, the Fremen's stillsuit, is also one of those sci-fi touchstones that has resonated with people ever since the book was published.
The stillsuit is designed to capture all the wastewater produced by the human body — including sweat, urine, tears, and even the water vapor in your breath — and recycle it into fresh, drinkable water. In the book, the Fremen's stillsuit is said to be so efficient at recycling water that while wearing one you would lose only a "thimbleful" of water a day.
While this too sounds fantastical, we already do something similar right now at the International Space Station (ISS).
"The [ISS's] Water Recovery System provides clean water for astronaut use by recycling urine, cabin humidity condensate from crew sweat, respiration, and hygiene, and water recovered from the Air Revitalization System," according to NASA.
"The Urine Processor Assembly, part of the Water Recovery System, was designed for 85% water recovery from crew urine and has been improved over the last year to now recover 87% because of analysis that showed there was still a margin against calcium sulfate precipitation."
"That distillate is combined with the condensate and processed through the Water Processing Assembly (WPA), which recovers 100% of the water it processes,” said Layne Carter, ISS Water Subsystem Manager at Marshall Space Flight Center. “As a result, our overall water recovery is about 93.5%.”
What's more, bedouin peoples around the world have adapted all manners of clothing to help preserve water, if not as fully as a stillsuit, at least they help keep your body cool and reduces sweating, which is a major source of water loss in the human body (which is why you get thirstier much quicker on a hot day than in the winter).
One of the other more notable means of water preservation among the Fremenon on Arrakis is water reclamation from the remains of the recently deceased.
If not one drop of water can be wasted if one is to survive, water is useless to the dead who no longer need it. So it makes sense to recycle the physical remains of the recently deceased to reclaim their water to be shared with the living. Given the hardships and social bonds that arise in an environment like Arrakis, it's easy to see how such a ritual could be interpreted as a final act of love and sacrifice to ensure that loved ones live on after one's passing.
We May Be Putting This to the Test Sooner than We Think
With the ramp-up to NASA's Artemis mission, there is obviously quite a lot of talk about how human beings will manage to sustain themselves in an inhospitable environment like the Moon, and one day even Mars.
Mars is actually a pretty obvious comparison to make when talking about Arrakis, a fact that is lost on exactly nobody. The similarities between the two planets is pretty obvious at first glance, but there are some major differences that show how Mars is even more inhospitable than a planet like Arrakis.
For one, even though water is one of life's most essential requirements, it isn't the most essential one. You can survive for about three days without water in most cases, but without oxygen to breathe, you'll die in a matter of minutes.
Mars, famously, has a very thin atmosphere of mostly carbon dioxide, with less than 1% of its atmosphere comprising oxygen. At least you can breathe on Arrakis, which puts it well ahead of living on Mars.
Another major issue with Mars is that while Arrakis is certainly very hot, it isn't totally outside of human tolerance if care is taken.
The average temperature on Mars is about -81 degrees Fahrenheit (-62 deg C), with -220 degrees Fahrenheit (-140 deg C) in the wintertime at the poles, and a summertime high of about 70 degrees Fahrenheit at the equator (-21 deg C).
While the equatorial summertime temperature sounds rather pleasant, the problem you run into on Mars is the same one you run into on Arrakis; namely, the lack of any surface water at lower latitudes.
Any human settlement of Mars would need to have access to water, which you'd need to both drink and to break down into hydrogen for fuel and oxygen for breathing. That means finding a way to survive in a climate that is nearly 100 degrees Fahrenheit colder than the coldest temperature ever recorded in Antarctica during the winter (-128 degrees Fahrenheit, -88 deg C).
And while you're out there trying to survive, you're also going to have to be mining a Martian glacier for that water you so desperately need. At least swinging a pickaxe might keep you warm, right?
"While human Mars mission plans are still in the conceptual stage, accessing and utilizing that water will be a daunting challenge," Matthew Chojnacki, a research scientist at the Planetary Science Institute, told Gizmodo.
Still, it's one we'd have to overcome if we ever have any hope of colonizing Mars one day. It might not have voracious, colossal sandworms digging around underground, but Mars is no picnic, and in many ways makes living on Arrakis a stroll on the beach by comparison.