How do you grow food in space?

The importance of circadian rhythm in keeping astronauts happy extends beyond the astronaut themselves. Because we all need to eat, and the food grown in space will be from plants that, again, are in no way used to having their internal clock and gravity thrown out of whack. So what’s the deal with space food? Jennifer Bromley is a fellow at Churchill College, Cambridge, and chief scientific officer at Vertical Future...

Jen - Vertical Future are an agritech technology and data company. And our mission is to improve planetary and human health by building a better food system. But the way how our technology has evolved means that it's now equally applicable off Earth as well as on Earth. And we are now leading a UK space agency funded project called Autonomous Agriculture for Space Exploration.

Will - What kind of crops are you finding work best up in space?

Jen - There's a variety of different crops that have been grown in space. So NASA has a very active crop science group who have two different growing facilities on the International Space Station. They're called Veggie and the Advanced Plant Habitat. And they've grown a number of different crops from things like lettuce through to peas. They've done radishes and I think my personal favourite is they've grown chilies and the astronauts particularly enjoyed eating those.

Will - When I think of growing plants as a humble earthling, I think of plants being buried deep in nice thick soil as a nutrient delivering mechanism. I assume that is probably a bit tricky.

Jen - Yeah. With no gravity, it's kind of difficult to deliver water and nutrients to plants in space, but it is completely possible and has been very much done already. So typically on Earth, when we're looking at vertical farming, we'll be typically using no soil, but we use substrates like jute. We use recycled matting, we use coco coir, but that all requires water and nutrients dissolved in the water to be delivered to them in liquid form, either by hydroponics or aeroponics. Now that's going to be a problem in space because the water will bubble up and float around the space station, which is really not what you want in an environment with a lot of electronics. And so what has been pioneered are these little plant growing pods that are known as pillows. And these pillows are essentially little watertight units that contain a water absorbent material. The plant grows through a small opening on the pillow, and then there is a port which if anybody's had any sort of interventions at hospital, you may recognise the sort of port that they will be injecting you with. And then what's happening at the moment is the astronauts who are running the experiments are manually injecting nutrients dissolved in water into the port, which then delivers it to the absorbent material around the plant root. So very much a soil like scenario, but the nutrients are provided externally through the water that's provided rather than it being sort of ingrained in the soil already.

Will - And as Matt Bothwell was speaking about just a moment ago, one of the biggest challenges about moving into space and onto other planetary bodies is going to be the shake up to our circadian system. Plants, very much the same and perhaps even more driven by the presence and position of light. How are you going to deal with that?

Jen - So the joy of growing in a controlled environment means that we can fully control when the lights turn on and when the lights turn off, the intensity of the light that we give them and the wavelength of the light that we give them. And so we can just play tunes with that to our heart's content. You can grow plants under a 24 hour constant light. They can start to look a bit funky. I'll be quite frank, they're not big fans of it. But it is possible to do it. But if you can essentially replicate the kind of conditions that you see on Earth, the sort of environment that the plant has evolved in, that's typically going to be the best environment and lighting condition that you can give to the plant in space. And so with the lights that we've developed at Vertical Future, we're able to do that and that's what we are putting on board the space station. We started to work on the ISS. The ISS works on GMT, it's working on a 24 hour cycle, so keep going on that. But you can start to shift plants away from the typical 24 hour cycle. There was some very interesting work that was carried out by Professor Alex Webb and his lab at Cambridge where they looked at what the optimum day length was for a variety of different accessions of one particular species. And they showed that most plants do not have a bang on 24 hour period. So you can shift away and you can make a plant more productive. If you do shift too much away from their optimal period, then they will start to reduce their yield volumes as well. So by being able to turn the lights on and off when we want to though, it means that we can keep the day to work for the plant and we can create the environment that the plant needs rather than try and sort of shift a plant onto the environment that we want to inhabit.