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Farming the Final Frontier

19 June 201607:10AMcoursework

In a glowing pink cabinet 400 kilometres above the surface of the Earth lives the loneliest lettuce alive.

Don Pettit's space zucchini, grown in nothing but a ziplock bag and a few drops of water. If only it were so easy. Image credit: Don Pettit / NASA

Plants in the International Space Station’s VEGGIE experiment grow in fibrous nutrient-rich pillows with water delivered from below. Light shines from racks of LEDs above, bathing the plants in a distinctive pink hue. By dropping the green light, which plants can’t use, VEGGIE saves valuable power but makes the plants inside look pitch black. The entire system is regulated by computer and monitored constantly from mission control.

It’s a long way from Earth, but this could be the future of farming.

Sowing the seeds

As with most space science, the craft of growing plants in orbit was pioneered by the Soviet Union. Cosmonauts tended wheat, peas and maize aboard the Salyut and Mir space stations in the 1970s and 80s. They were the first to grow an entire generation of plants in space, growing some cress-like weeds from seeds until they produced seeds of their own. NASA eventually caught up, but after the fall of Skylab in 1979 they were limited to short tests aboard the Space Shuttle.

Even today the Russians are ahead. While NASA astronauts ate their first lettuce with much fanfare earlier this year, Russian cosmonauts have been eating half their crop from their own greenhouse for years, with the other half sent home for more rigorous testing.

Putting down roots

Astronauts mostly still eat canned or dried food. Their atmosphere is still maintained not by photosynthesis, but by electrolysing oxygen from water, then scrubbing carbon dioxide away with canisters of lithium. Both the water and the canisters are supplied, like their food, from Earth.

As we explore further into the solar system, those supply runs are going to get harder, and the costs of failure higher. Right now losing a spacecraft, as both SpaceX and Orbital Sciences did last year, means a return to dehydrated food. During a Mars mission it might mean famine.

Taking plants up with us seems like the obvious solution, but it’s trickier than it looks.

Lettuce leave

Plants evolved to live on Earth under the steady pull of gravity. Without it soil simply doesn’t drain. Instead, water clings to plants’ roots and stays there, cutting them off from vital nutrients. The same happens to air around leaves: without ventilation plants quickly use up all the carbon dioxide nearby and starve in a stagnant pool of photosynthesised oxygen.

VEGGIE is the latest attempt at solving these problems, but introduces some of its own. The pillows keep roots nourished and well-drained but are quickly depleted and need replacing from Earth. Plants are exposed to the space station’s atmosphere for ventilation but then have to be sanitised to ensure that lettuce, and not microbes from the air, is all the astronauts are eating. And sometimes, for an exciting new reason every time, the plants just refuse to grow.

These problems will be solved too, but at the cost of complexity. Just how much of Earth’s environment are we able, and willing, to re-engineer in orbit?

Further afield

Farming might never be worthwhile in low Earth orbit. For the rest of the solar system, especially Mars, it makes a little more sense. Thanks to a series of robotic explorers, we know quite a bit about Mars’ soils. Enough, in fact, that we know we can find very similar ones near volcanoes here on Earth. Just like their Martian cousins, they’re rich in trace elements, poor in nitrogen and very slightly alkaline.

A team of Dutch scientists, not NASA or Russia, are leading this particular field. They are well into their second attempt at testing these soils, growing carrots, tomatoes, cress and rye in painstakingly prepared pots of Mars-like dirt. And the almost-Martian soil, statistical glitches aside, seemed to work just as well as earth from Earth.

“That was a real surprise to us”, said Dr Wieger Wamelink, lead researcher on the project at the University of Wageningen in the Netherlands. “It shows that the Mars soil simulant has great potential when properly prepared and watered.”

The team plan to crowdfund a third experiment to start in April 2016.

“If the crops prove to be safe enough to eat, the funders will be invited for dinner where a ‘Martian meal’ will be served that includes the harvested crops; at least for those who dare!” Wamelink said.

And yes, potatoes will be on the menu.

Down to earth

Mark Watney wannabes aside, the real result of this research might end up closer to home. The Space Station is testing plants in the most hostile artificial environment imaginable. Simulated Martian soils are showing how to farm the most barren parts of our own planet. With increasing populations, growing urban sprawls and an erratic climate, it’s easy to see why this might be useful stuff to know.

Perhaps, rather than pink glowing cushions or bitter Martian grit, the future of astro-agriculture lies right here on Earth.

This article was originally written for SCOM2208 Science Writing at UWA in Semester 1 of 2016. As far as I can tell, the marker's favourite thing about it was the headline...

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