- how an off-Earth base could quickly become self-sufficient -


Growing Food Growing enough food to support an Initial Crew had a lot of details. Bryce Meyer describes how hydroponics and aquaponics can be used to achieve this.

In order to achieve Earth independence, one would need to provide for all of the nutritional needs of the growing colony. How could this be done?

There are three major goals when it comes to figuring out how to grow food off Earth:

  • Meet the nutritional needs
  • Provide enough culinary variety
  • Minimize labor
Meeting the nutritional needs of the small colony is fairly well understood. We would need to provide sufficient calories, the macronutrients (carbs, fats, & proteins), and the micronutrients. There may need to be some adjustment due to the reduced gravity environment. For example, there may need to be more calcium in the diet to address the accelerated bone loss.

Many cultures around the world don't have as much culinary variety as the developed world. So culinary variety isn't necessary to survival. None-the-less, a variety of foods is highly valued and provides a nutritional buffer to ensure that the various nutritional needs are being met with redundancy.

One of the biggest time consumers for an Earth independent colony turns out to be the amount of time it would take every day producing and processing food as well as preparing food to be eaten. Any tools and equipment that would reduce the amount of time to do these tasks would be well worth it. Blenders, food processors, etc can be real time savers.

Plants need water, plant food, and fertilizers. Fortunately, we know where these things can be obtained on the Moon.

Water is present in large quantities in the permanently-shadowed craters at both poles of the Moon. It is tricky but apparently doable to have telerobots working in those craters to harvest and process the ice into distilled water. In addition to it being used for propellant, sanitation, and drinking, it would also be used to grow plants. The International Space Station is currently recycling its water at a rate of 93%. At this rate, one liter of water would last as long as 14.3 liters of water without recycling. So, recycling can significantly reduce the amount of water that needs to be harvested and processed. The water would have nutrients added to it and pumps would pump that solution to the top of sheets of wires holding troughs which would hold the plants. As the water comes down the troughs the plants would get the nutrients that they need.

Plants also need CO2 to grow. Fortunately, NASA's 2009 LCROSS mission demonstrated the presence of carbon when it struck and kicked up some icy lunar dirt into the sunlight for analysis. Some basic chemical processes would need to be employed to convert those carbon-containing chemicals into CO2 which the plants could use. It is true that plants grow more quickly if the CO2 levels are elevated. But then crew would likely need to be working in that environment so one would need to bear that in mind when designing the greenhouse portion of the habitats.

Plants also need fertilizers. The main fertilizer is called NPK standing for nitrogen, phosphorus, and potassium. Nitrogen was also found in the form of ammonia in the LCROSS results. Nitrogen would definitely need to be recycled. Phosphorus and potassium is in the form of KREEP rocks which the Apollo missions found and brought back for analysis. So, those rocks are fairly common on the Moon. Plants can pick up micronutrients through their roots. Composting is a way of recycling those.

The different types of food grown would include plants, animals, algae, and fungi. Which animals would be raised is discussed in the next page and algae is part of aquaponics which is discussed below. Fungi includes mushrooms which will be an important source of protein and a useful part in the waste processing system. Herbs and spices would play an important role in making the food palatable. Certain fibrous plants could be grown but organic fibers would probably mostly be synthetic due to their minimum waste and reprocessing requirements. Fibers would also be very important in the production of filters.

Hydroponics is the preferred way to start growing plants. One doesn't have to deal with processing the abrasive lunar regolith and dealing with the health hazards of the lunar dust. Hydroponics can be done in a very controlled manner maximizing the amount of food grown over time without concern for natural seasons.

The current concept for hydroponics would be that about 35% of the volume of habitat(s) would be dedicated to hydroponics. Rails attached to the habitat roof would have wires coming down with cross wires forming sheets upon which troughs could be attached. Like shower curtains, these sheets could be pushed aside to make way for the colonists as they plant and harvest the produce. LED lights with just the right frequency of light to optimize plant growth could be hung from the rails so that sheets of lights would shine on sheets of plants to the right and left.

The Achieving Earth Independence Project is itemizing what plants can be grown hydroponically, and what selection of food times would meet the nutritional and culinary needs of the colonists.

The first and easiest meat to be grown would probably be fish. Tilapia is, of course, a popular fish for consumption. Algae drapes as seen here could grow using LED lights. That algae would be provided to fish in tanks as a fairly efficient means of producing meat.

Trees mostly provide fruits and nuts. But trees typically need soil, take up large volumes, and take a long time to grow. Small, fruit-bearing trees could be transported and contained within pots of soil made from crushing lunar rock and adding organics. But initially, most of the fruits and nuts would need to be from non-tree sources such as strawberries, melons, berry bushes, and peanuts.

Everything will need to be recycled including plant waste. Herbivorous fish could consume some of the plant waste. Mushrooms are a productive way of dealing with organic waste. But perhaps the most efficient approach is the use of a bioreactor which uses microorganisms to break down molecules into reusable forms. Herbivorous insects can also be used to consume plant waste (e.g. leaves) and certain fish enjoy eating insects.

By necessity, the greenhouses will need to be under a significant layer of lunar dirt. This is because, the sun occasionally put out a large amount of radiation during solar particle events which can damage the plants. So, how to get solar power down into the covered greenhouse. Two solutions suggest themselves:

  • Solar panels with electrical wires coming in to power LEDs
  • Solar concentrators with fiber optics bringing light through the covering dirt
We take for granted the amount of power that we get from the sun for free to grow our crops. But, in an Earth independent colony, we would need to either have large solar drape farms and/or solar concentrators. This is not only to provide the light for the plant to grow but all of the pumps and other power demands of the colony.

To be truly Earth independent, one needs to ensure that the amount of labor needed to survive can be provided only by the colonists and their equipment. Fortunately hydroponically-grown plants don't require weeding so that saves a lot of time. Planting and harvesting aren't a major time consumer but maintenance is. Still, it is currently estimated that if would take no more than 17% of the man-hours available to provide sufficient food for the colonists. But, any piece of equipment that would help with the workload of handling plants would be very important.

We should note a very important project that has been going on for years at the University of Arizona - Tucson. They have the Lunar Greenhouse Project at their Controlled Environment Agriculture Center (CEAC). They are systematically doing the work necessary to figure out exactly how this can all be done and they've made good progress. In fact, their work has been applied to the base at the South Pole where fresh produce is provided to the staff there during the winter. It is from their work that the estimate of 35% of the volume being hydroponic greenhouse came from. Here is a video link describing their work.

After the initial UniHab, later habitats could be delivered and set up which would specialize in different aspects of growing food. In this way, the economies of scale and automated robotics could reduce the amount of labor needed to feed the growing colony. Specialized habitats could include: GrainHab, GardenHab, OrchardHab, DairyHab, & BarnHab.

With the proper design, enough food could be produced to support a growing colony.

Next: Nutrition