If you want to start a space farm, head for an asteroid. It seems there's enough fertiliser zipping around the solar system to grow veg for generations of space colonisers – and researchers are already beginning to grow viable, edible plants in space.

Asteroids are a hot topic with the 3 December launch of Japan's Hayabusa 2 spacecraft, which aims to return a sample from carbon-rich asteroid 1999 JU3. And astronauts are spending longer and longer in space, with the first crew to spend a full year aboard the International Space Station due to launch in 2015.

"Longer human missions will require the company of plants, in terms of providing both food and psychological comfort," says Bratislav Stankovic at the University of Information Science and Technology in Ohrid, Macedonia. His team is one of many running experimental mini farms on the ISS, and one of the first to grow plants successfully.

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