ESA's HOBI‑WAN project will test whether Solein, a microbial protein developed by Solar Foods, can be produced in microgravity using urea from human urine instead of ammonia. Solein is ~78% protein (with all nine essential amino acids), ~10% fiber and ~6% fat. The experiment will confirm if gas fermentation works reliably in orbit before trials on the ISS and wider adoption for long‑duration Moon or Mars missions.
ESA Will Test 'Solein' — A Protein Powder Made by Urine‑Fed Microbes — in Space
ESA's HOBI‑WAN project will test whether Solein, a microbial protein developed by Solar Foods, can be produced in microgravity using urea from human urine instead of ammonia. Solein is ~78% protein (with all nine essential amino acids), ~10% fiber and ~6% fat. The experiment will confirm if gas fermentation works reliably in orbit before trials on the ISS and wider adoption for long‑duration Moon or Mars missions.
10:21 PM, 11/11/2025Science
ESA to trial microbe‑made protein from urine in orbit
The European Space Agency (ESA) has launched the HOBI‑WAN project (Hydrogen Oxidizing Bacteria In Weightlessness As a source of Nutrition) to evaluate whether a powdered protein called Solein can be produced in microgravity using urea derived from human urine.
Developed by Finnish company Solar Foods, Solein is a microbial single‑cell protein that on Earth is about 78% usable protein (containing all nine essential amino acids), plus ~10% dietary fiber and ~6% fat, with the remainder being carbohydrates and minerals. On Earth the company makes Solein using ammonia as the nitrogen source; HOBI‑WAN will test whether the gas fermentation process works in orbit when urea replaces ammonia.
"This project aims to develop a critical resource that will increase human spaceflight autonomy, resilience and the well‑being of our crews," said Angelique Van Ombergen, ESA chief exploration scientist. If the in‑orbit experiment succeeds, Solar Foods plans to scale the demonstration to the International Space Station, according to Space.com.
"The aim is to confirm that our organism grows in space as it does on the ground, and to establish the fundamentals of gas fermentation technology for use in space — something never done before in human history," said Arttu Luukanen, senior vice president of space and defence at Solar Foods.
Microbial growth and gas behavior change in microgravity, so verifying that the fermentation process remains efficient, safe and reproducible off Earth is essential before Solein can be considered a practical, sustainable food source for long lunar or Mars missions. Producers say Solein can be flavored and incorporated into many foods — from spreads to pasta — making it potentially adaptable for astronaut menus.
Why it matters: producing nutritious food from waste streams like urine could reduce supply needs, increase mission autonomy and support longer human presence beyond Earth.