And you'll never guess what is enabling this growth - urine. The German Space Agency is the prime actor in this movement. Visitors to the agency's offices can taste the tomatoes, which are not exactly the tastiest they've eaten. But they're fine for astronauts.
The tomatoes are grown atop of columns packed with pumice stone – solidified lava that is riddled with holes – home to rich colonies of bacteria. These microbes feed on the urine pumped through the pipes, some bacteria convert ammonia into nitrites and others convert this into nitrate salts, i.e. fertilizer.
This is just like the nitrogen cycle that takes place naturally in soils and watercourses on Earth. As well as urine, this closed-loop biological system could be used to process leftover food or leaves that drop from a plant.
The test in space is scheduled for later this year, The rocket will contain two miniature greenhouses, as well as tomato seeds, a tank of synthetic urine and bacterial colonies. The spacecraft will spin to simulate gravity and water the system. It is expected that the tomatoes will germinate and the urine will produce tomatoes.