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THINKING SPACE NATURE

TOMATOES IN OUTER SPACE

Do plants really need soil and sunlight to grow? Not necessarily, as experiments in space have shown. The international EDEN ISS project, for example, might be able in the future to supply astronauts – and people living in very dry or cold regions – with fresh fruit and vegetables.

Mars. A place of longing – and the preparations for its conquest are in full swing. Would it really be possible for us humans to survive over a long period on the Red Planet? And what would our food supply look like? Perhaps like it does in the American movie “The Martian”, where astronaut Mark Watney (Matt Damon) grows potatoes – while wading through his own excrement that is being used to fertilise the spuds. Not the most pleasant of thoughts. But not unthinkable either.

VEGETABLE CULTIVATION ON THE ISS

Cultivating vegetables in outer space is not science fiction. Since 2002, astronauts on the International Space Station (ISS) have been experimenting with plant cultivation in space. In 2015, they were allowed for the first time to eat salad grown on the space station – in a live broadcast before the eyes of the entire world. Since then, NASA has been pushing ahead with its research programmes to provide astronauts on long-term expeditions with fresh fruit and vegetables.

Other space experts are also trying to grow plants under artificial conditions. An approach that we terrestrials will ultimately benefit from too, because in times of climate change and a growing world population, new solutions are needed more than ever to secure food production in regions with hostile climates. For example, in deserts – or in cold zones such as the Antarctic.

FRESH VEGETABLES FROM THE ETERNAL ICE

At the South Pole, one of the most inhospitable places on earth, the EU-funded project EDEN ISS has passed its field test: since 2018, the model greenhouse has been supplying the crew of the Antarctic station Neumayer III – run by Germany’s Alfred Wegener Institute for Polar and Marine Research (AWI) – with cucumbers, lettuce and the like. During the first year, a total of around 270 kilograms of vegetables were ripened in two converted shipping containers. The greenhouse was developed at the German Aerospace Center (DLR) in cooperation with international partners.

For their record harvest in the land of perpetual ice, the scientists created conditions that allowed the crops to grow even better and faster than in nature itself – regardless of weather, sun and season. And completely without soil, but with lots of technology: controlled by computers, the plants are sprayed with a water-nutrient mixture. Special filters and UV radiation clean the air of fungal spores and germs. Insecticides and pesticides are rendered thereby unnecessary.

LESS ENERGY CONSUMPTION THROUGH NEW LED TECHNOLOGIES

Just like a space station, the EDEN ISS greenhouse has a closed air cycle. The advantage is that the water given off by the plants can be collected and reused. A mixture of blue, red and white LED light lets the artificial sun shine for 16 hours a day. DLR experts estimate that increasingly powerful LEDs will eventually reduce energy consumption, which currently is relatively high.

DLR, together with AWI and other research partners, intends to further refine the EDEN ISS production processes by 2021. DLR’s small satellite Eu:CROPIS is currently rotating in space with two greenhouses on board in which tomatoes are supposed to ripen under Mars and Moon conditions – using fertiliser from artificial urine and energy from solar cells. In the meantime, the EDEN ISS greenhouse has also been made available to other research groups from around the globe who want to conduct plant breeding experiments in the Antarctic. According to DLR, NASA has been among the first new cooperation partners: the American space agency has sent its original NASA salad seeds, which also grow well on the International Space Station. The common goal is to further develop the greenhouse concept, which will in future supply Moon and Mars stations – and perhaps also terrestrial regions.

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