Mars is and has long been a popular choice for human colonization should we want or need to leave Earth. But Amanda Hendrix and Charles Wohlforth say that if we’re going to go live somewhere else in the solar system, then Saturn’s moon Titan is the best choice.
Hendrix, a planetary scientist who works for the Planetary Science Institute, and Wohlforth, an award-winning science writer, have just come out with a book, Beyond Earth: Our Path to a New Home in the Planets (Pantheon, 2016). They talked about Titan and the book last week at Town Hall Seattle.
“We don’t, as human beings, normally do big expensive things for no reason at all,” Wohlforth said. “That led us to thinking about what would we want on another planet, or what we would be getting away from here on Earth, that would drive us to want to move to another planet.”
While humans have long had a case of wanderlust, Wohlforth said the reasons to colonize another planet go beyond that.
“Environment drives colonization; it has in the past, and we don’t always call it environment,” he said. “We call it overcrowding or we call it wealth seeking, but really in our society economics is how we talk about environment a lot of the time.”
A key to colonization, he said, is having the resources to do it and to keep it going.
“Making colonies requires technology and it also requires wealth and the ability to make money, and in our world that’s often meant that government gives private industry the money to get started,” Wohlforth said. “Colonies need a reason to exist environmentally or economically, they need major government investment to happen, and ultimately they need a way to support themselves without help from home.”
Hendrix said they developed five main criteria they considered when evaluating a place as a possible site for a human colony. It should have an atmosphere, a magnetosphere, manageable temperatures, a decent amount of gravity, and a hospitable landscape. Among those, she said the first two are most important, as the atmosphere and magnetosphere could shield colonists from harmful radiation.
It was easy to winnow the list. Venus was rejected out of hand as a super hot hellhole with a poisonous atmosphere that may well be volcanically active.
“It’s really not the greatest environment for a human settlement,” Hendrix understated, “but what’s interesting about Venus is that in that thick atmosphere there is an altitude at which air that we like to breathe is stable. You could, in theory, have a floating city of balloons that are filled with air and where humans could live.”
On Mercury, Mars, or the Moon people would likely have to live underground to avoid radiation. That’s not very appealing, either.
“It’s not really what we’re going for,” Hendrix said. “We’d like to find a place in the solar system, if possible, where we can live on the ground and have a decent amount of radiation shielding.”
Jupiter has a lot of interesting moons, but the king of planets churns out huge doses of radiation and is not a very hospitable place. When you get out to Saturn, though, Titan catches the eye.
“One of the number-one reasons is that it has an Earth-like atmosphere,” Hendrix said. It’s mostly nitrogen with some methane, and is at about 1.5 times the pressure of our atmosphere on Earth. Titan has no magnetosphere of its own, but for much of its orbit it lies inside Saturn’s magnetosphere, so they can share.
“We think that for our key points of shielding from radiation by either an atmosphere or a magnetosphere, Titan is a very good place,” Hendrix said. “This really sets Titan apart from the other places that we looked at in the solar system for a long-term human colony.”
More positive features
We know a lot about Titan through data gathered on 124 fly-bys of this moon by the Cassini spacecraft. Titan has a lot of Earth-like features. It has clouds, rain, swamps, wind, and sand dunes. It has surface liquid—lakes and seas of methane and ethane. (Water would freeze.) It’s cold there, but Titan has pretty constant temperatures across seasons and latitudes.
There’s also a virtually limitless energy source on Titan. Reactions between its atmosphere, sunlight, and energy from Saturn create hydrocarbons that cover the moon’s surface. Colonists could drill down and get water from Titan’s liquid subsurface ocean, separate out the hydrogen and oxygen, giving them the chemistry needed to burn the hydrocarbons.
“You can imagine settlers on Titan having a power plant that takes in methane and water, and the output is energy and breathable oxygen,” Hendrix said. “So it could work out quite well for our colonists—plenty of energy.”
Don’t pack your bags yet
Setting up a colony on Titan would not exactly be a piece of cake, especially if you didn’t survive the trip. NASA has compiled a long list of potential health risks for astronauts, many of them related to radiation exposure, and concluded that space flights of more than a year are too risky for humans. It would take seven years to get to Titan with current technology.
“These are risks that, without some technology leaps,” Wohlforth cautioned, “we’re not going to Saturn. We simply can’t get there and have the astronauts be safe.”
The key to the trip is finding a way to go faster. Wohlforth said the commercial space sector is making some headway on this, and a NASA scientist named Sonny White is actually working on a propulsion system that uses quantum virtual particles and is also tinkering with a warp drive. That notion drew applause from the Trekkies at the talk, but Wohlforth noted that there’s a pretty good dose of skepticism out there. While warp drive may be “poppycock” as one headline writer opined, it’s not unreasonable to think that some smart engineer is out there cooking up a way to make space ships really zip.
Challenges aside, the urge to go and explore and colonize is strong. Hendrix and Wohlforth touched briefly on a lot of topics that are covered in more depth in the book—such considerations as how society might develop elsewhere, how reproduction might change in a Titan colony, and other challenges and opportunities.
“We really like Titan as a potential human colony location,” Hendrix concluded. “We think it has a lot to offer.”
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