Space Agriculture
Corinne Moore, Technical Business Development Associate
4 minute read
If you’re anything like me, with lists and plans galore, the weekly grocery trip can often feel like a planned mission. Between scanning for coupons and optimizing my aisle routes, I don’t often stop to think about where exactly my food comes from or how much is grown every year. Working in the space industry changed all of that, as now everything mundane has a new spice to it (pun intended) when viewed through the lens of space travel. What kinds of foods will our future space colonizers be farming and how much will they actually need? Are extended stays on other planets actually sustainable or will they be inherently limited by the resources available? Without further ado, let’s dive into those questions and more in this latest KMI Column!
Whether you’re enjoying a casual dinner with friends or carefully crafting your post-workout snack, humans go through a lot of food in a single year. The average American adult consumes on average one ton of food, or 1,996 pounds, every year. For us, attaining that food is as simple as heading to our local grocery store. The future colonizers of Mars and beyond, however, will have a far different experience. As we’ve discussed in other columns, shipping items to space is expensive, the cost largely determined by weight. While routine shipments of food and supplies go to the ISS over the course of a year, the same will not be possible for longer-distance missions. Human Martians will have to cautiously monitor supply use and find creative ways to maintain a food source without relying on frequent shipments.
An important aspect of agriculture on Mars or other planets is understanding how plants grow differently in a microgravity or reduced-gravity environment. Studies aboard the ISS in the Columbus module, dubbed Veggie, started in 2014 with the planting and harvest of red romaine lettuce and continue to this day. Other plants successfully grown on the ISS for human consumption include Tokyo Bekana Chinese cabbage, Mizuna mustard, Waldmann’s Green leaf lettuce, Red Russian kale, Dragoon lettuce, Wasabi mustard, Extra Dwarf pak choi, radishes, lentils, and dwarf wheat, to name a few.
Through these experiments, many factors have been identified that have significant impacts on not just what grows well in microgravity, but how microgravity impacts growth. For example, in the ISS PESTO experiment, the crew found that wheat plants grew 10% taller than they would on Earth, while mustard experienced smaller seed production. Microgravity plays a role in every part of plant development, from root structures to how the water flows from soil to stem, and even the level of calcium produced by the plant’s cells.
While the experiments aboard the ISS provide invaluable insight into how plants grow in microgravity, growing plants on Mars will be quite different. Contrary to popular belief, and as we’ve discussed in previous columns, microgravity is not the same as zero gravity. On Earth, we are all subject to a gravitational force of 9.8 m/s2. Astronauts and everything else aboard the ISS are subject to 90% of the Earth’s gravity, but this is perceived as weightlessness due to the constant state of free-fall during orbit. In comparison, the surface of Mars has even less gravity at 3.71 m/s2, which is about 38% of Earth’s. Current experimentation provides an excellent baseline for what we can expect from plant growth on Mars, but results in that lower gravity environment could easily prove more extreme, for better or worse.
Another key difference between the ISS and Mars is distance. Regular shipments to the ISS occur throughout the year, bringing everything the astronauts need for daily life, maintenance, and onboard science experiments. Mars will be an entirely different story. From liftoff to landing, Perseverance’s journey to Mars took nearly 7 months. In contrast, the record-breaking fastest crew flight from Earth to the ISS was achieved in 3 hours and 48 minutes aboard Progress 70 in 2018. What this means is that anything that can be utilized from resources already on Mars absolutely must be used. Thankfully, soil on the Red Planet does contain many of the nutrients necessary for plant growth, such as nitrogen, potassium, and phosphorus, but fertilizers and additives will likely be necessary. Carbon dioxide is also available in abundance on Mars (96% of the atmosphere to be exact), which is great for the plants, and will contribute to the oxygen the people caring for them will need.
Given all of those needs, we can’t forget about water, and plants need a lot of it. To grow enough wheat for a single loaf of bread, you need an astounding 154 gallons of water. Flying all of the water needed for crop production, without accounting for human consumption, just isn’t feasible due to astronomical costs and weight. Mars, overall, is mostly desert, but imagery studies theorize that, due to the existence of channels and valley networks along the surface, there was once flowing liquid water. While the atmosphere does contain traces of water in the form of vapor, the icy polar caps hold the greatest promise for usable H2O. Between the water available on Mars and the water reclamation systems we already use on the ISS to recycle and purify water from sweat, breath condensation, and urine, Mars agriculture remains a viable endeavor.
Bringing humans to Mars and growing crops will be a challenge, to say the least, but the experiments of the past, present, and future will set our future Martians up for success. It wouldn’t be a KMI Column if I didn’t at least briefly touch on the problem of space debris and how it pertains to space agriculture. Right now there is a lot of debris up there (33,340 objects that are large enough to track at the moment), but one day the mission of KMI and other similar companies will reduce that number and alleviate the problem of orbital debris. When that wonderful day arrives, KMI and our competitors will have to find another purpose for our technology, and transporting shipments of agricultural products could be one of them. Whether hauling fertilizers to barren outposts, or food products from production centers to research stations, the capability to remove debris is one we need to perfect in order to also complete our space-based shopping lists.
Recommended column to read next: A Meal with a View: Space Food