Read the full story in Science News for Students.
Pee on a spaceship seems like a problem, not a solution. But someday astronauts’ urine could become food for genetically engineered yeast. And the breaths these space travelers exhale could be used to help those yeast cells work like tiny factories. They might churn out the ingredients used to make plastics. Or they could become the raw materials for nutrient supplements that keep astronauts healthy. Each might help humans survive on a trip to Mars or beyond.