If you’re looking forward to start farming in space, head for an asteroid. Researchers are already beginning to grow viable, edible plants in space as there is enough fertiliser zipping around the solar system to grow veg for generations of space colonisers.
“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.
Space farmers have had a tough row to hoe. Nearly every space shuttle flight through the 1980s and 1990s carried experimental plant payloads. But just as human bodies seem to need Earth-like gravity to function, so plants seemed to struggle in Microgravity.
“It appears to influence cell biochemistry,” says Stankovic. The plants displayed strange genetic mutations, grew in unpredictable and undesirable shapes, and seeds did not germinate or grow well. They also had trouble producing a second generation of fertile seeds, a key milestone for sustainable space farming.
But now, Stankovic and his colleagues from the University of Wisconsin-Madison have made a capsule that enabled two generations of seeds to successfully grow on the ISS.
The capsule tightly controlled soil moisture, light, air temperature, humidity, and levels of carbon dioxide and ethylene – a hormone plants release into the air when they begin to ripen. A mesh held down a base of fertilised gravel in which the plants could spread their roots.
Once astronauts installed the system, it was remote-controlled and monitored from the University of Wisconsin. They grew Arabidopsis thaliana, a small, edible flowering plant that is often used as a model species.
Not only did the plants produce seeds, but 92 per cent then germinated successfully. Some were grown on the ISS and others back on Earth. There was little difference between the two, the team found. The space seeds had their protein stores packed a little differently and the plants’ branches grew in slightly different directions. But these are small details, Stankovic says. “It is likely that the previous failed attempts had to do with inadequate control of the growth environment,” he says.