Stanford_torus_under_constructionDon Davis (image released into public domain)An artist's rendering of a generation ship.

Note: This essay contains thematic spoilers, but does not reveal key plot turns or surprises.

"I have to hold my breath underwater!" a character discovers in Kim Stanley Robinson's 2015 book "Aurora."

The science fiction master's interstellar journey begins and ends at sea, and is suffused throughout with awe at its beauty and danger.

Robinson's metaphor is willfully obvious. Water stands in for life's fantastically complex, dynamic mosaics. It lends drama to his characters' adventures and foils their technological hubris.

2015 was the year the literary versus genre war ended au body image 1451612265 size_1000Hatchett Book Group

At its core, "Aurora" is a coming-of-age story. But, in the tradition of much speculative science fiction, it has an argument: the human project to expand past our own solar system is doomed before it begins.

Robinson sets the journey on a generation ship, a closed environment built to sustain centuries of explorers, animals, and plant life on the long trek to a nearby star.

This is more than just a fictional invention — I wrote in 2014 about the DARPA-funded, astronaut-led project to build such an ark. But "Aurora" takes the opposite tack of most spaceward sci-fi. Page by page it unspools the uncountable problems of star travel, showing that in aggregate they exceed our capacity to solve.

It's a credible and surprisingly hopeful point of view.

There's an old joke in science: Applied physics is called chemistry, applied chemistry is called biology, and applied biology is called sociology. Each is more complex, vague, and unpredictable than the last. The problems Robinson lays out proceed neatly along that ladder of intricacy.

Like any good spacefaring science fiction story, "Aurora" neatly deals with the physical problems of moving a ship from one star to another: lots of energy, lots of shielding, lots of time. But in the book's early pages more difficult chemistry problems arise.

A closed ecosystem is in constant flux, and even small unbalances threaten to tip it into an unsustainable spiral. That's why carbon emissions pose such a danger on Earth. In smaller systems, such instabilities are further amplified. One character, Devi, explains the problem to a child in the first chapter. Maintaining balance becomes the central and all-consuming activity of the explorers' lives:

'Oh, I’ve told you before. It’s always the same. Everything in here has to cycle in a balance. It’s like the teeter-totters at the playground ... You don’t have to keep it perfectly level, but when one side hits the ground you have to have some legs to push it back up again. And there are so many teeter-totters, all going at different speeds up and down. So you can’t have any accidental moments when they all go down at once ... And our ability to figure out how to do that depends on our models, and really, it’s too complex to model.' This thought makes her grimace. 'So we try to do everything by little bits and watch what happens. Because we don’t really understand.'

On Robinson's ship, centuries of life have produced slightly too much salt and depleted slightly too much phosphorous — and this imbalance, however minor, threatens the entire craft into an ecological death spiral.

Still, humans are ingenious. Spit and duct tape jerry-rig one fix, and then another. Soon a whole chain of temporary solutions to the chemical deficiency approaches a permanent one. But deeper problems arise at the next rung of the complexity ladder. Bacteria on board are breeding and evolving faster than the small human population can adapt. Each generation lives less time and develops more poorly than the last. This dilemma is more to be endured than resolved. At the sociological level, they struggle with the violence and selfishness of human nature.

Given the surface gloom of his thesis, Robinson's greatest feat may be that the vision in "Aurora" is ultimately hopeful. Even as it advances a radically environmentalist and anti-expansionist vision of the future, the book revels in technological possibility. Robinson imagines a third millennium of human ingenuity, focused not on evacuating our cradle planet but achieving a sort of communion with all the teeming richness it offers. The best human life, he argues, takes place not out in the void, but under the glare of our own sun and astride our home planet's waters.

Kim Stanley Robinson has an excellent essay about interstellar travel on Boing Boing that's definitely worth a read. You can find it here.