Why a German lab is growing tomatoes in urine

A fish tank brimming with urine is the first thing you see when you enter Jens Hauslage’s cramped office at the German space agency, DLR, near Cologne. It sits on a shelf by his desk, surrounded by the usual academic clutter of books, charts and scientific papers.

Rising from the centre of the tank are two transparent plastic cylindrical columns – around a metre in height. Spreading from the top of each tube is a bushy, healthy-looking tomato plant with green leaves, flowers and even a few bright red tomatoes.

The plants have been specially bred to be grown in space. This experimental tank of urine, pipes and plants is the original prototype for a satellite designed to prove that tomatoes could be cultivated successfully on the Moon or Mars.

Right now, almost all the food on the International Space Station (ISS) is ferried up in cargo ships from Earth. The only exception is a few lettuce and cabbage leaves astronauts have managed to grow in a hydroponics solution. Most of the water on board the ISS, however, comes from astronaut urine. Liquid waste from washing, sweat and the toilet is almost totally recycled using a complex processing system. Today’s urine is tomorrow’s coffee.

But what if you could use the useful salts in astronaut urine to grow food? If humans are ever to live for long periods on the Moon or Mars, they will need a self-sustaining food supply. “You will need more than protein bars,” says Hauslage.

Read more at BBC Future