This New Way to Make Protein Could Be What Feeds Astronauts on Long Space Journeys

There is no grocery store on Mars and restocking from Earth will take several months. No matter how much food future astronauts on the Red Planet can bring for the trip, they will inevitably have to create their own food in an inhospitable environment. Whether they’ll take the fancy farm-to-table route with locally sourced potatoes, as Matt Damon’s character did in the 2015 film The Martian, remains to be seen. But they might have an even more scientific option.

Create protein from scratch.

That’s the goal of a partnership between the European Space Agency and a company called Solar Foods, which emerged from a scientific research program less than a decade ago. Solar Foods opened its first large-scale production facility in 2024.

Don’t miss any of our unbiased technical content and lab reviews. Add CNET as your preferred Google source.

The project, called HOBI-WAN (for “hydrogen-oxidizing bacteria in zero gravity as a source of nutrition”) in a nod to the Star Wars films, is a space version of a process that Solar Foods is already working on here on Earth. This effort involves growing bacteria in a vat of water, air and nutrients, then drying and turning them into a protein powder called Soleine for human consumption.

A key next step will be to test Solein production on the International Space Station.

“Providing a sustainable and nutritious food supply that meets the energy needs of the crew is one of the greatest challenges in human spaceflight exploration beyond low Earth orbit,” the ESA said in a blog post. “In cases where pre-deployed food depots or continuous resupply missions from Earth are impractical, resource-intensive, or technically infeasible, cost-effective alternatives are needed.”

From bacteria to proteins

The central objective of the HOBI-WAN project is to determine whether the production of protein-rich powder can take place under microgravity conditions.

The process is complex, but it will essentially be about letting nature take its course.

“Solar Foods produces solein through a process called gas fermentation,” Arttu Luukanen, the company’s senior vice president of space and defense, told me. The gas fermentation process, he says, creates single-celled organisms that feed on hydrogen gas and use it to “sequester” carbon. From there, the bacteria are fed “life minerals” using ammonia as a source of nitrogen and hydrogen.

All the ingredients go into a bioreactor with water and gases that are pumped “kind of like a big SodaStream,” Luukanen says. This provides the bacteria with the appropriate environment to reproduce, which they do very quickly. Once the bacteria have reproduced in sufficient quantities, they are harvested. A portion is set aside to seed the next cycle in the bioreactor, while the rest is carefully dried and pasteurized.

These dried and pasteurized bacteria form the Solein product, composed of 78% protein, 6% fat (mainly unsaturated), 10% dietary fiber, 2% carbohydrates and 4% mineral nutrients. Luukanen says the powder can be flavored in different ways and imparts “a very mild umami flavor” on its own.

How to Make Protein in Space

Solenoid production will be more difficult to achieve in space. The weightless environment, along with the limited cargo capacity and reduced space for the bioreactor, add challenges that the ESA and Solar Foods believe they can solve.

“[The] The main difference for the experiment on board the ISS is the absence of gravity, which means there is no buoyancy, which significantly changes the behavior of liquids and gases,” explains Luukanen. The other challenge is limited physical space. Solar Foods uses bioreactors that can hold 20,000 liters or more, while the bioreactor heading to the ISS will be significantly smaller – “a few dozen liters”.

Additional measures will be required for gas safety, process monitoring, quality assurance and maintainability, as there will be no bioprocess engineers on board to monitor the process. Nor will the product made in space be ground into powder, at least not on the ISS. In the event of a leak, having a cloud of powder floating in a weightless environment would not be ideal.

So in space, Solein will likely be served in paste form.

Recycling in space

The last important factor is the ingredients. They will need to be modified to account for the lack of resources available during long-term spaceflight. Recycling has long been a key part of life in space, and this will be the case for Solein production as well.

This means using CO2 from crew breathing and recycling hydrogen gas produced when the ISS uses electrolysis to transform water into oxygen for the crew. On Earth, manufacturing Sun requires a lot of water.

There will also be substitutions, such as using urea instead of ammonia, because ammonia would be dangerous in the event of an accident. But that doesn’t mean astronauts will use urine like they do for “recycled coffee“.

“On Earth we use ammonia, but for the ESA project we decided to use synthetic urea instead, mainly because it is not potentially dangerous like ammonia is in the event of a spill,” says Luukanen. “Recovery of urea from urine is in principle possible, but given the small amount of urea needed, it may not make sense, especially if extracting urea from urine involves complex and heavy equipment.”

Feeding astronauts during long-duration missions

A trip to Mars requires much more time than an excursion to the Moon. NASA’s next Artemis II Mission will see astronauts circle the Moon for the first time in almost half a century, but the journey will only last 10 days. In terms of food, it’s not very serious. But March — observed by space agencies as well as by Elon Musk — is much, much further away, and travel time will last for months and months. En route to the Red Planet, astronauts will need to bring more than a picnic.

If Project Solein proves successful, the amount of food it generates could theoretically feed a team of astronauts for hundreds of days while using far less cargo space than current space meals. Luukanen says that, at the time the project was designed, the only thing the astronauts would need to carry would be mineral salts, and they wouldn’t need much of that.

“Even for five-[person] crew, 900 day mission to Mars, we are talking about [less than]100 kilos of mineral salts,” he explains.

Other technologies could also help recycle nitrogen and minerals, allowing astronauts to reuse these materials on site, further expanding the food supply.

Using the protein powder, astronauts could prepare all kinds of dishes with the right additional ingredients. Luukanen says Solar Foods has developed recipes ranging from ice cream to cream cheese ravioli. Some of these were showcased during NASA’s Deep Space Food Challenge, which highlighted methods for long-term food solutions, including a light-free food growing method called Nolux and a closed ecosystem capable of autonomously growing food and preserving insects for use in an astronaut’s diet.

It might not be what you’d expect from a Michelin-starred restaurant or even your neighborhood deli, but it’ll probably be better than a steady diet of baked potatoes grown on Mars.