This type of protein could become a key food source for astronauts on long-duration missions to the moon, Mars, and beyond. Image credits: Solar Foods.

Food is ridiculously expensive in space. Every meal astronauts eat is freeze-dried, vacuum-packed, and launched at enormous cost — sometimes over a thousand dollars per pound. It works for short missions, but if we ever go to Mars, that model simply won’t hold up.

So, what if instead of shipping food, we grow it in space?

Astronauts have already been experimenting with growing crops for over a decade. But the European Space Agency (ESA) believes there’s a better way: with a box full of bacteria.

Their new project, called HOBI-WAN, aims to build a bioreactor that takes the air astronauts exhale, the water they recycle, and even the nitrogen they excrete, and turn it all into edible protein.

A Bacteria Cocktail for Space Food

Feeding astronauts sustainably is one of the biggest challenges in long-duration spaceflight. ESA’s solution looks like a high-tech miniature brewery vat. Instead of yeast, though, it contains a non-toxic bacterium called Xanthobacter.

These microbes don’t need sunlight or sugar; they eat hydrogen. You feed them carbon dioxide (which astronauts constantly exhale) and a mix of hydrogen and oxygen you obtain by splitting water through a process called electrolysis. This energy could come from solar panels, for instance.

Feeding a handful of astronauts in space is no easy task. Image credits: NASA.

You feed this cocktail, along with some nitrogen, to bacteria. They feast and multiply, producing a sludge. When this sludge is dried, it becomes a nutritious, protein-rich powder.

Solar Foods, the company that invented it, says it’s about 65-70% protein, with a composition similar to soy or beef. It’s a “B-vitamin-packed, neutral-tasting powder” that can be added to pasta, baked into bread, or turned into a shake. It is, quite literally, protein made from air and electricity… and pee.

Here on Earth, the company uses ammonia for its bioreactor; but in space, you can’t just get ammonia. So, they’ll have to use urea, a replacement which can be obtained from the astronauts’ urine.

“This project aims at developing a key resource which will allow us to improve human spaceflight’s autonomy, resilience and also the well-being of our astronauts,” says Angelique Van Ombergen, ESA’s Chief exploration scientist. “For human beings to be able to implement long duration missions on the Moon, or even one day, to go to Mars, will require innovative and sustainable solutions to be able to survive with limited supplies. With this project, we the European Space Agency is developing a key capability for the future of space exploration.”

It Already Works on Earth… But There’s a Catch

A spread made from this type of bacteria-made protein could soon feed astronauts. Image credits: Solar Foods.

Solar Foods already makes this protein on Earth. But in space, things get complicated, mainly because there’s no gravity.

Gas fermentation depends on dissolving gases like hydrogen, oxygen, and carbon dioxide into a liquid so bacteria can “eat” them. On Earth, this is easy: you bubble gas through a liquid and let buoyancy do the mixing. In microgravity, there’s no “up,” and bubbles don’t rise.

“The aim of the project is to confirm that our organism grows in the space environment as it does on the ground, and to develop the fundamentals of gas fermentation technology to be used in space — something that has never been done before in the history of humankind,” Arttu Luukanen, senior vice president of space and defence at Solar Foods, said in a statement.

“The behavior of gases and liquids in microgravity is vastly different due to lack of buoyancy,” Luukanen added.

How do you get the gas into the liquid and to the microbes, uniformly and efficiently, when the basic physics you rely on don’t exist? Turns out, this is a safety nightmare.

The core ingredients, hydrogen and oxygen, can make a mixture we commonly call “rocket fuel”. Working with these gases is, to put it mildly, explosive. The HOBI-WAN experiment box, destined for the ISS, has to be extremely safe to ensure the gases don’t mix or escape into the cabin. And the ESA says it is.

If This Works, It’s Pretty Big

The experiment will be housed in a standard “middeck locker” (about the size of a microwave) and will contain three separate experiments. Astronauts will have to draw samples from it during the mission to see if the bacteria are growing as they should. They’ll firstly check that the physics works as expected before moving on to actually using the food.

The so-called *bioeconomy *(using renewable energy and microorganisms to generate useful products) is taking off both on Earth and in space. Here on Earth, the problem is scale. Plenty of remarkable processes have been demonstrated in a vat, but for them to make a sizeable difference, you need industrial scale activity, and that part is different. For space, the challenge is getting it to work in a challenging environment without gravity.

ESA’s project will help both sides. By showing how the process can be contained and how it behaves in microgravity, it will offer important clues for scaling the technology. Ultimately, this approach could make our food system more sustainable.

People sometimes look at the cost of space missions and ask, “Why bother? Why spend billions up there when we have so many problems down here?”

This is a good example. It shows how the extreme, unforgiving constraints of space act as a high-pressure forge for human innovation. We are forced to invent radical, hyper-efficient ways to manage air, water, and waste simply to keep a handful of astronauts alive. In doing so, we accidentally create the very tools we need to support billions of people on an increasingly stressed planet.