Taking the field out of the farm: Growing produce in space is closer than we think

Images from the 1950s show the people of the future — that's us — travelling in flying cars and living in biodomes, lush with fruits and vegetables for the taking. While that's not the case, it's not for lack of trying.

In reality, our ability to grow food in space is limited to a few plants on the International Space Station (ISS). NASA, along with many other space agencies around the world, has been trying to change that for almost 70 years, and the advances keep coming.  

A new paper published in the journal Open Agriculture has traced the history of growing food in space from its beginnings in the 1950s to today, and paves the way for colonizing even the distant reaches of space with autonomous food supply.

Why is it so hard to grow food in space?

There are really lots of reasons, but the biggest reason is actually light. Even though the sun is burning bright out there in outer space, there are places that don't experience the same diurnal daylight like we do here on Earth. Plants are a lot like people: they're used to the typical 24-hour days of alternating light and dark; in fact, they have a molecular clock timed to it. If you were to find yourself on the moon, with almost two straight weeks of daylight and no night at all, followed by two straight weeks of darkness with no light, your body wouldn't know how to react. It's the same for plants.

That was the first problem facing scientists looking to grow food off Earth, which led to an invention that we use every single day: LEDs. I spoke with Ray Wheeler, a NASA Exploration Research and Technology scientist at the Kennedy Space Center and the author of the paper.

"The patent for using LEDs to grow plants was developed through NASA-funded research, and this was in 1990, quite a while ago," he said. "At that time LEDs weren't all that efficient, but they fit a niche for use in space plant chambers that are typically very small. LEDs have continued to improve remarkably as a technology, but it was really their use for space application to grow plants that kind of brought this up to the forefront."

So, just when you think "what has space research done for me?" they go and make LEDs the invention they are today.

Once the light is figured out, what do the various space agencies want to grow?

The goal is to give the astronauts and cosmonauts fresh foods with more bio-available nutrients to keep them healthier longer. They could and do take supplements for their nutrition, but there is something about biting into a nice ripe tomato to get your vitamin C instead of just taking a pill. Plus, you absorb a lot more nutrients coming from something living than something compressed down into a pill.

It's also more than just nutrients: there is a need to keep some level of normalcy or Earth-like living out there in space: tending, caring and rearing food for yourself, and the pleasure taken by the simple act of eating, is positive for anyone's mental health, let alone someone stranded on Mars. 

For shorter missions, small supplemental fruit and vegetables are the goal, but obviously longer missions and more permanent space settlements will require staple crops like wheat, other grains and legumes.

What do growth chambers for space look like?

Generally pretty small at this point. The ISS has a 0.15-square-metre growth chamber. Clearly not enough to feed them, but enough to look at the feasibility of upscaling it.

The reality is the growth chambers that may one day exist on the moon or on Mars aren't that much different from what we already see on Earth. In particular, hydroponics have been a huge focus of space-farmers.

Wheeler explains: "The use of re-circulating hydroponics to conserve your water and nutrients so you don't discharge them into the environment — and you save water and you recycle the nutrients very efficiently — this is something that we have to do in space systems when we'll be setting them up. But it's very applicable to Earth settings as well. We're always under pressure to preserve water and nutrients and minimize environmental impacts."

So farming in space is going to have the same limitations as hydroponic operations here on land, complete with the need for power, closed air systems and the space to grow. Movies like The Martian really didn't do a bad job showing what space agriculture will likely look like one day.

How tough will space be on plants?

That's one thing that is going to be really important to understand, and there simply hasn't been enough work done on it yet. Low-gravity experiments have been done on Earth, and certain plants — like tomatoes — tolerate low-gravity situations quite well. However, the bigger problem up in space is the radiation. Plants are living organisms with DNA just like ours, and we know that radiation is problematic for DNA: it can cause all sorts of mutations very quickly and do all kinds of damage to the cells. 

A question is: Can we conventionally breed or genetically engineer staple crops for resistance or tolerance for radiation without losing yields?

The next frontier in space agriculture is really not improving the tech, but improving the life that will live in that tech.

I'll give the last word to NASA scientist Ray Wheeler:

"The approach to date has been largely to try and continue to improve the engineering and the environmental management to accommodate the biology, and we're kind of getting to some limits here in terms of how far you can go with the engineering and the hardware. Now we really need to think about can we adapt the biology to fit the constraints of the environment, and I think the answer to that is yes."