This SciShow video is supported by Linode!

Go to linode.com/scishow for a $100 60-day credit on a new Linode account. [ ♪ INTRO ♪ ] If we want to grow food in space, we’re gonna need to start with bacteria. Among other things.

Because anyone can stick a plant in some dirt and hope it’ll grow, but not only does space not have dirt – it also doesn’t have the entire interdependent community of organisms that make that dirt productive. That means researchers who want to feed astronauts on long-term missions are thinking about everything – absolutely everything – hat agriculture needs to work, from why their plants might need fish, to how we can digest those plants better by feeding our gut microbes. Sound simple?

No, I didn’t think so either. Let’s look at some of these big ideas. The average human consumes just under two kilograms of food per day.

Launching a kilogram into orbit can cost anywhere from under $5,000 to $100,000! You don’t need an accountant to tell you that’s not going to work for long-term missions. For that, astronauts will need food autonomy, which is the ability to produce food independently without relying on Earth.

This has, to put it mildly, a lot of considerations on many scales. The first bit of good news is that, just like here on Earth, well-designed food systems can help sustain life beyond just the calories they contain. They can be part of a bio-regenerative life support system.

These are the systems that can supply our basic needs. For example, they can make oxygen to breathe or recycle waste back into useful material, sort of like a miniature version of our own food web down here on Earth. Deciding which organisms to send as part of these systems is more complex than just picking out some seed packets.

Researchers need to ask questions like: Which species reproduce easily? How much space do they take up? What’s their growth rate?

How do they tolerate fractional gravity or microgravity, and what resources do they need to sustain growth? Finally there’s the question of how much of it is edible, and how many nights in a row you can actually stand to eat it. Let’s start with options for produce.

A common science fiction trope is space stations with giant forests, but we’ll have to start on a smaller scale. We can’t eat whole trees, so we need to think a little more agriculture-y. That doesn’t mean we’re going to have cornfields in space, but plants will have to be a foundational component.

For example, duckweed is a tiny aquatic plant, and it’s attractive in this context for several reasons. It reproduces by budding, so it’ll multiply rapidly and easily. It takes up very little space as it grows, and it’s a very good source of protein for a plant.

We can also turn to algae. In addition to having many of the same advantages that duckweed has, a single-celled species in the genus Chlorella was the subject of a German study on board the International Space Station in 2019. This study showed that algae might be a viable alternative or supplement to more traditional plant options.

But while algae and duckweed are efficient, they need to be highly processed and are not exactly what most astronauts would consider comfort foods. It’s just not going to replace Grandma’s mac and cheese. But more traditional crops have a waste problem - space is notoriously limited on spaceships, and something like a delicious tomato comes with inedible vines and leaves.

It took a lot of precious resources to grow those vines, so we don’t want to just eject them into space. So NASA-backed researchers have been investigating solutions. They have genetically engineered a tomato variety that makes bigger fruits with less foliage than traditional plants.

But, if we want to mimic the efficiency of natural systems as much as possible, we will need to include more than just plants. Maybe someday we’ll have huge starships or lunar colonies that can hold more traditional farm animals, but right now, we’ve got to think a little smaller and a lot wetter. Aquaculture systems are a sustainable and space-efficient way to provide protein and fat-rich dietary requirements for spacefaring humans while making sure that resources get recycled over and over.

These systems might focus on aquatic invertebrates like mollusks or shrimp, which grow quickly, use up little space, and can eat those extra plant bits we discussed earlier. And waste from aquatic animals can be used to feed algae. A French team interested in food autonomy for the European Space Agency’s planned Moon Village looked into using sea bass and the meagre fish.

These species could provide nutrients essential for human brain health, while their waste could be fed to algae. The whole thing loops like a satisfying TikTok. In our constructed ecosystem, we even want to consider insects.

They’re a great source of bio-available fats and proteins. But even insects are not our smallest consideration. For something as crucial as food, you need to scale down even further and think about the microbiome.

Microbiomes are tiny ecosystems of bacteria, fungi, single-celled eukaryotes, and a whole host of other critters that help break down food elements that otherwise don’t get consumed. We can maximize the food output by designing and curating our selections of microbes in our food production systems. But microbiomes aren’t just in soil and water.

They are in the guts of animals, including humans. The diversity and abundance of gut microbes influence what nutrients we extract from our food. A better understanding of the human microbiome may help us select bacteria species that allow us to get the most out of the food we do eat.

The idea is, astronauts may one day be able to take personalized prebiotics - basically bacteria food - that support desired species. Researchers are working to understand our microbes and learn what we can do to support them. That way, we could allow astronaut bellies to do more with less, and decrease the amount they would actually have to grow.

Living systems can be incredibly complex, and food production is already complicated before you add space to the equation. But an astronaut’s gotta eat, so these challenges must be solved before any real long-term space exploration can occur. So you know, if you ever wanted to don a pair of space overalls and take advantage of the most rural living possible, space farmer just might be the future career for you!

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