Rich McEachran asks, “How feasible is it that we’ll be cultivating plants in space on a large scale by 2100? The science is there but the logistics isn’t… yet.”
Rich is right. We can grow plants in space, albeit it’s not necessarily the best environment to do so without some modification to those plants. While sunlight is plentiful, space is cold and dry. You’re more likely to be bathed in radiation than water. And there’s no gravity. Plants, like us, did not evolve to live and thrive in these conditions. But we can overcome them. Research is ongoing about how we best grow plants in this artificial environment, just as it is on Earth. But the principle is well proven.
The bigger question is why we would want to grow plants in space. There are three potential audiences for such a technology.
Feeding the astronauts
The first is astronauts. You can only store food so long before some of its nutrients start to break down. If astronauts are going to be spending a long time in space, and particularly if they are away from regular supply runs, then growing food in space would be vital. Whether we need to grow it on a large scale will be a question of how many astronauts we have up there.
My sense at the moment is that for all the enthusiastic talk of trips to Mars (some more realistic than others), we’re still a long way off mass scale human space travel (I don’t include short space-tourism hops in this). By 2100, it’s very likely we will have a lot more people in space, in national, international and commercial programmes. But most of these will be close to the Earth and undertaking short trips rather than extended stays where it would make sense to grow fresh food.
NASA certainly plans to have a well established moon base within the next decade, funding permitting. And I suspect other nations will be keen to establish their own footholds, given that the Moon will be a critical gateway for further travel. If you are spending tens of days in either lunar orbit or on Artemis station, then some fresh vegetables would doubtless be very welcome. But feeding a few astronauts could hardly be called large scale production.
So it doesn’t look to me like serving this audience would justify large scale agriculture in space.
Feeding the population
With climate disruption threatening agriculture around the world, it’s worth asking the question of whether we could grow food in space to feed Earth’s population. Sadly, the answer is a fairly quick ‘no’. While the logistical problems that Rich refers to are easier going from space to Earth than vice versa, the particular challenges of growing in space mean that it’s probably not a viable location for growing food to feed the planet. Quite apart from anything else there is the issue of water.
Plants need water to grow, in one form or another. We can bring water up from Earth but it is heavy and dense, and right now the cost per kilogram of payload is around £2200. That’s gonna be some expensive lettuce.
We can mine ice from asteroids or from the Moon to water our plants, but even this is far from cheap when compared to water literally falling from the sky onto your crops. It might be viable to support a few astronauts. It’s not viable for feeding the general population.
Feeding the machines
Perhaps one of the most practical reasons for growing plants in space at scale is for the raw materials they can produce. Plants are incredibly efficient at turning sunlight into sugars, for example – much more so than any human engineered process. With genetic engineering, it’s feasible that between now and 2100 we will be able to engineer species of plant or algae that create all sorts of valuable resources from a base stock of water and sunlight. And the additional advantages of zero-G manufacturing (for example, 3D-printing complex and even organic parts without scaffolding), might justify the cost of sourcing the water.
I’m still dubious as to whether this might be happening at large scale, even by 2100. But I think it will certainly be happening, and likely outside of a pure research framework.
Space farm 2100?
So, to answer Rich’s original question: “How feasible is it that we’ll be cultivating plants in space on a large scale by 2100? The science is there but the logistics isn’t… yet.” I think it’s entirely feasible. We could do it. It’s just not clear that the demand is there to support it.
I would dearly love to be proved wrong on this. I strongly believe humans should spread out from Earth, explore and yes, colonise, our solar system and beyond. We’re the only species we know of within an enormous range of Earth. Who else is going to see and catalogue the galaxy’s wonders? But right now, we’re a long way from a voyage to the final frontier.