Concept art by Rick Guidice for the NASA Ames Research Center

Beer is the oldest human-made alcoholic beverage that we know about. People living in the Yellow River Valley (now in China) were brewing some sort of fermented grain alcohol around 9,000 B.C.E., and the first barley beer was probably made in the Zagros Mountains of Iran around 3,400 B.C.E. We’ve been drinking it, in all its ethanol-and-carbonation-filled glory, for pretty much as long as we’ve been people. Some of our earliest writing is even about beer: the Hymn to Ninkasi, the Mesopotamian goddess of beer, was not only a praise song but also a way of remembering the standard beer recipe. It stands to reason that, if humans manage to get off of earth and head for the vast reaches of the galaxy, we’d want to have some beer to drink along the way.

Which brings us to a conundrum: beer requires many ingredients that really grow best on a nice, healthy, soil-and-oxygen-rich planet. Spacefarers—particularly those on a generation ship or a self-sufficient space station, i.e. people who live in space—are going to have an interesting and difficult time making something that we’d recognize as beer, in the quantities humans tend to like to consume beer in. I recently had the pleasure, if that’s the right word for it, of trying to solve this problem for Lsel Station, a self-sufficient completely non-planetary location in my novel A Memory Called Empire, which is why I am now duty-bound to bring you the answer to how to make beer with only what you can grow on a generation ship.

Ingredients necessary for beer: water, yeast, and a starch that the yeast can work upon.

Ingredients you want if you’d like your beer to taste vaguely like the beer we know: malted barley, hops.

Let’s start with yeast. The usual yeast is a brewer’s yeast, most often Saccharomyces cerevisiae, which happens—helpfully—to be the same species as the yeast that makes bread rise. Yeasts are little live creatures—single-celled microorganisms that love to eat sugars and transform them into carbon dioxide and alcohol. They need to be kept alive. A generation ship would have had to bring a yeast colony, perhaps in the form of a sourdough starter, and feed it regularly with starches and sugars, in order to be able to have a steady supply of small organisms to brew beer with. As the generation ship matured as an ecosystem of its own, it might develop airborne yeast strains that could be harvested—but it also might not, as the usual air-purifying filters of a spaceship would kill those off. So, to have beer (and bread), the dwellers on our hypothetical ship probably have to keep their yeasts going generation after generation, in some sort of Yeast Vat. Okay. Plausible.

Next: water. If our generation ship isn’t producing adequate water supplies, we have bigger problems than a lack of beer. Let’s assume there’s enough water.

Now the hard part: starches. This is hard because even a large generation ship—let alone a permanently parked mining-and-refinery city-in-space like my Lsel Station—doesn’t have that much square footage to grow anything. There also is, well. A lack of soil. Now, traditionally in science fiction generation ships and space stations solve this problem by growing their crops hydroponically—essentially, in water. (That is, when they don’t solve this problem by having everyone eat Food Cubes, or get perfect steak dinners out of the local replicator.) And it turns out that you can grow barley hydroponically…but only to the point of getting it to the ‘fodder’ stage, where it’s useful for feeding animals, but not so much for harvesting the seeds for malting and brewing. To get the barley that far, you need some soil, at least for any barley variety we currently have. (This is one of the reasons that beer prices will rise as climate change reduces the acreage available for barley to grow here on earth—we haven’t yet been able to optimize it for growth in greenhouse conditions.) So our generation ship won’t be growing barley for beer.

But!, you say. People brew beer with all sorts of grains! And this is true. Beers are made of sorghum, millet, and agave. Sometimes they are even made of rice. And rice, it turns out, is our solution here: rice is a brilliant hydroponic crop. However, rice grains lack the enzymes that naturally convert starches into sugars for the yeasts to feast upon. Traditionally, this is dealt with by introducing koji, a Japanese strain of Aspergillus mold, which provides the missing enzymes. It is possible that our enterprising generation-ship brewers could have brought along mold colonies—in fact it’s quite likely, as another major generation-ship crop is almost certainly funguses of all kinds. Another option is to add kelp to the rice mash—particularly a variety called ‘sugar kelp’, Saccharina latissima, which has plenty of the enzymes that convert its starches into sugars.

Even better, sugar kelp is a crop that helps keep hydroponic ecosystems healthy—it’s easy to grow, its byproducts stimulate other plant growth, and it even filters the hydroponic tanks.

So now we’ve got rice, kelp, yeast, and mold. How do we make this taste like beer? Hops. And, remarkably enough, hops do grow hydroponically. They’re a specialty crop, certainly, and our generation ship bioengineers are unlikely to devote an enormous amount of resources to growing it when they could be using that space for actual food… but it is possible to have occasional hop crops, as a luxury item.

And thus: space beer. It’ll be cloudy and not that alcoholic (from all the rice), it’ll be a luxury not a staple (because of the hops), and it will taste like the ocean if the ocean were fermented (because of the kelp). But it’s beer.

Probably. It’s beer enough.

Originally published in December 2018.

Arkady Martine writes speculative fiction when she isn’t writing Byzantine history. She is overly fond of borders, rhetoric, and liminal spaces. Her novel A Memory Called Empire is published by Tor Books. Find her on Twitter as @ArkadyMartine.