Inside ESA’s HOBI-WAN Project

Our Bureau - : Dec 19, 2025 - : 3:05 am

For more than twenty years, astronauts on the International Space Station have relied on meals packed on Earth, food that has travelled by truck, ship and rocket before reaching their trays in orbit. It is a system that works as...

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But as Europe prepares for longer human missions to the Moon and eventually Mars, a simple, uncomfortable question has emerged: what happens when resupply is no longer an option?

That question now sits at the heart of a new European Space Agency (ESA) project with a playful name and a serious purpose. HOBI-WAN, short for Hydrogen Oxidising Bacteria in Weightlessness as a source of Nutrition aims to see whether a protein-rich food, produced from gases and a special bacterial culture, can be made in microgravity. If successful, it could offer astronauts a new way to feed themselves far from Earth.

A Food System that Starts with Thin Air

The core ingredient in the experiment is Solein, a powder created by Finnish company Solar Foods. It looks much like flour but is made using a completely different process. The bacteria behind Solein feed on hydrogen, oxygen and carbon dioxide rather than sunlight or soil. On Earth, the mix includes a small amount of ammonia for nitrogen. In space, urea, something humans produce naturally, will take its place.

ESA is funding the work through its Terrae Novae exploration programme, which supports technologies needed for future missions to low Earth orbit, the Moon and Mars. OHB System AG, a German aerospace contractor with decades of experience designing hardware for the ISS, has been chosen as the prime contractor. The company will work with Solar Foods to adapt Solein’s production process for space.

Inside the Experiment: A Bioreactor the Size of a Suitcase

The entire HOBI-WAN experiment is planned to fit inside a standard ISS middeck locker, a small metal cabinet astronauts can lift by hand. Inside it will sit a bioreactor containing a nutrient solution and bacteria. Tanks of hydrogen, oxygen and carbon dioxide will feed the system, and sensors will monitor temperature, pressure, pH levels and gas flow.

One of the biggest engineering challenges is ensuring that gases can be injected safely. Hydrogen and oxygen are highly reactive, and microgravity causes liquids to move unpredictably. For this reason, the hardware must be built with special cartridges and containment systems to prevent leaks or sudden bursts. The experimental box will host three separate test environments, and astronauts will occasionally extract samples during the mission.

“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 survive with limited supplies.”

A Partnership Shaped by Expertise

OHB System AG’s experience working with life-support systems and ISS payloads made it a natural fit. “Since the European Columbus module was commissioned, OHB has been developing, operating and maintaining scientific payloads for the ISS for over two decades,” says Jürgen Kempf, the HOBI-WAN Project Manager at OHB. “The insights we gain here could also help address global challenges on Earth such as resource scarcity and food security.”

Solar Foods brings the biological know-how behind Solein. For the company, adapting a terrestrial food technology for orbit requires a different mindset. “Their expertise in evaluation and certification, especially with respect to mandatory safety requirements, will help us design a system that is suitable for the space environment,” explains Arttu Luukanen, the company’s Senior Vice President for Space & Defence.

First Earth, Then Orbit, and One day, the Moon

The first eight months of the programme will focus on developing a ground-based scientific model. Only once the process is stable on Earth will engineers begin building a flight unit for launch to the ISS. If it performs well, the technology could become part of future life-support systems, recycling gases produced by astronauts into food with minimal waste.

And beyond space, HOBI-WAN’s technology could play a role on Earth. Regions with poor soil, unstable supply chains or water scarcity could eventually benefit from a food source that does not need farmland or sunlight.

For now, though, the experiment remains the size of a suitcase, sitting in a laboratory on the ground. But if it works, future astronauts on the Moon or Mars could one day sit down to a meal whose ingredients began as thin air, a reminder that survival in space relies as much on biology and ingenuity as it does on rockets.

Hobi-wan / Solein / Solar-foods / European-space-agency-esa /

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