The SyFy miniseries Ascension has reminded me of the biggest—really, the absolute biggest problem facing missions to other planets and isolated human colonies (and the real reason why the Ascension mission would never have worked in 1963).
It’s the fact that we don’t know how to create and maintain a closed, sustainable ecosystem. And if you don’t have one of those, I don’t care what else your long-range mission has… it’s doomed to fail.
In Ascension, hundreds of colonists are (supposedly) on a 100-year mission to Proxima Centauri. This means that the ship is supposed to provide its own recyclable atmosphere, its own food, fuel and other supplies, from only the things they have on-board, for 100 years. This is a conceit that science fiction has been hawking for years, usually making it look easy to keep sealed environments going on their own. But the truth is not nearly so convenient: Maintaining sealed ecosystems is damned complicated and damned hard.
And though it’s rarely talked about outside of die-hard engineers, we’ve never managed to create such a closed and sustainable ecosystem. Not even today.
At present, any humans that want to work in space have to take all of their supplies with them. Even air. There is some ability to recycle some chemicals, including air and water; but it is limited and imperfect. Sooner or later, even the best-maintained mission is going to have to import supplies, from the most specialized and complex, down to air and water, in order to survive. Or they’ll have to come home.
Knowing this, scientists have attempted to create sealed and sustainable test environments, to make sure humans can survive over long periods. The idea is to use these as a guide for creating sustainable environments in places where we can’t simply ship fresh supplies to them every few months… like Mars, or other long-range destinations.
The most famous, Biosphere 2, created a sealed environment, with its own agriculture and supporting animals, and eight people attempting to live inside it on its first mission. (I repeat: Eight people. Look at the size of it.) But the experiment was considered a failure, owing primarily to wildly fluctuating CO2 levels, severely-dropping oxygen levels, and the death of most of the vertebrate species and all of the pollinating species. (A second mission was ended prematurely because of external management issues and vandalism by members of the first mission.)
BIOS-3, an experimental Russian facility, had some success with 2-3-man habitats that aggressively recycled materials, but it was not 100% sealed. Other experiments have also attempted to mimic sealed environments, but at less than 100% of actually being sealed.
So far, no one or group has found a way to generate a fully sealed and recyclable environment for long-term human use. The incredible chemical complexities of maintaining atmosphere and producing sustaining food and water are still beyond our abilities to master, or even fully understand.
All of that means that if we’d actually launched a ship like Ascension in 1963… it’s occupants would probably all be dead by 1965. So, in a way, it was clever of Ascension to admit to audiences that “we can’t send a sustainable community to space today, so we’ll just have to pretend in order to see what happens.”
But we will have to continue to experiment on sealed habitats and what it will take to maintain them; otherwise, our future space program will be forever limited to the reach of a live supply train of goods and essentials to keep our explorers alive.