WPenner's Blog

Using satellite imagery to improve terrestrial results readily springs to mind when thinking of agriculture and space. Companies like Metaspectral, SpaceAlpha Insights, and Wyvern are just a few of the Canadian companies attempting to improve agriculture through the application of artificial intelligence (AI) and imagery captured by satellites. Science and Economic Development Canada's space strategy for Canada (2019), claimed "Fewer than 10 per cent of Canadian farms currently use satellite imagery to support activities. Increasing this rate to 25 per cent by 2027 could lead to cost savings to farmers in the range of \(650M to\)1.3B, depending on crop type. In addition, greater use of satellite navigation in precision agriculture could lead to cost savings of $800M per year by 2027." ¹

Reading papers from Wheeler² and Katayama, et al.³, though I appreciated the work being done to set up agriculture in space. Developing agriculture in space provides multiple benefits. Human consumption of plant-based nutrition is a significant consideration. Since the 1950s, experiments have also held out promise for bioremediation of environmental factors like CO\(_2\) and O\(_2\).

Algae Experimentation Leads to Plants

Early experiments with algae and cyanobacteria showed initial positive results with great light absorption. Ultimately, the systems didn't produce enough O\(_2\) and compromised closed life support systems. Finally, when they resisted being made tasty, the line of research was abandoned.

After abandoning algae cultivation, research turned to plants which could grow under low light intensities, have a compact size and high productivity, and tolerate urine recycling (especially sodium stress from NaCl). Researchers from around the world created lists of crops which met the requirements. An interesting aspect of all the lists of plants showing the most promise because of nutritional or bioregeneration properties is that they always include sweet potato.

Other plants that regularly made the American lists included wheat, soybean, potato, rice, sweet potato, lettuce, and peanut. Plants tested over the years included: wheat, lettuce, potato, sweet potato, rice, cowpea, peanut, tomato, and alliums. Wheat usage is interesting.

NASA scientists at Johnson Space Center showed that an 11 m\(^2\) plot of wheat was enough to scrub CO\(_2\) and produce O\(_2\) for a single human for 91 consecutive days. This experiment took place in a terrestrial test bed, as 11 m\(^2\) in space still comes at a premium. On the other side of the planet, Japanese research progressed in similar but distinct directions.

JAXA Goes Beyond Plants

JAXA recommended just four plants to provide the average person a balanced nutritional diet: rice, soybean, green-yellow vegetable, and sweet potato. These leave nutritional deficiencies, being low in sodium, lipids and some amino acids. Something more than plants would be required to meet all human nutritional requirements.

Animal (especially insect) protein supplementation could address plant deficiencies. Adding loach fish to the in-space rice paddies is one such possibility. Loach fish already inhabit terrestrial paddies, tolerate poor water quality and can survive partial paddy drying by gulping air and absorbing it in the digestive tract. The Japanese consider its nutritional value high. There are other things than fish on the menu, though.

Besides fish, Japanese researchers explore using silkworm, hawkmoth, drugstore beetles, and termites as food. In some Asian countries, these insects have a long history as culinary ingredients. None of these insects compete with humans for the same food, preferring plants which humans find inedible. Research suggests insects have other uses in space, too.

Beyond food, there are good reasons to include insects in space agricultural systems. These systems improve their functional performance when insects upgrade inedible or low-grade biomass for animal or human consumption. Careful selection of insects can avoid competition with humans and provide useful complements. For example, insects degrade the inedible parts of vegetables or allow faster degradation of waste for use by plants. In space systems, scientists must also consider the possibility of lower atmospheric pressures or even a total loss of pressures.

While pressure at roughly sea level (101 kPa) is most common for terrestrial agriculture, Canadians explore the possibility of plants growing at lower pressures. Researchers at the University of Guelph used low pressure chambers, demonstrating radish plants' ability, for exampl e, to grow at 10 kPa pressures. Rapid decompression of 1.5 - 2.0 kPa for up to 30 minutes also produced no apparent damage. Which means plants can withstand pressures far lower than humans.

While far from exhaustive, the ideas from these papers paint a picture of space agriculture far richer than the application of satellite imagery. ⁴