Overcoming challenges in Martian and Earth agriculture: a path to sustainable food production

Discover Mars' food future! Will pioneers depend on Earth provisions or grow crops for Martian meals? Dive into extraterrestrial agriculture's potential in this captivating article.

This article examines Mars food from a first principles perspective, focusing on the essentials for survival. However, when we discussed this article with Robert Zubrin, the president of the Mars Society, he shared his insightful perspective. He emphasized that while intrepid explorers may be satisfied with canned peanut butter or similar survival foods, attracting civilians for settlement requires a strategic approach that takes into account diverse dietary preferences from various cultures. Furthermore, to encourage procreation on Mars, it is crucial to make the environment appealing to women as well.

In the pursuit of establishing a sustainable human presence on Mars, one of the most critical aspects to consider is the development of a self-sufficient food production system. Martian agriculture must overcome numerous challenges, including energy requirements, security concerns, and the need for advanced controlled environment agriculture (CEA) techniques. This article explores these challenges and potential solutions, highlighting the importance of innovative research in the fields of genetic engineering, photosynthesis, and farm automation for both Martian settlers and Earth's growing population.

A colonist family having dinner on Mars by Mid-journey

Energy Requirements for Martian Agriculture

In our previous article, we discussed the current methods for feeding astronauts on orbital stations. Now, let's take a step further and explore the potential challenges of feeding the first Mars pioneers or even a full-fledged Martian colony. What will the nutritional requirements be, and what physical limitations will they face? Building on our earlier discussion of Martian habitats, we will delve deeper into this fascinating subject.

To start, let's consider two scenarios: 1) a pioneer mission with six people on a 12-month round trip, and 2) a colony consisting of 1,000 individuals living permanently on the Red Planet. In the event of a mission, we have considered the most optimistic mission duration achievable using nuclear rocket engines. If the mission, for instance, takes two years, the mass of food reserves should be multiplied by 2 accordingly.

Every astronaut will need approximately 2,500 calories daily. Assuming the food has a nutrient density like wheat (3,600 Cal/kg), this means each person needs a minimum of 700 grams of dry food daily, an equivalent to 250 kg/person/year. As a result, pioneers would require about 1,500 kg of dry food for the proposed 12-month trip, while a colony would need 250 metric tonnes of food each year.

Artistic representation of a kitchen inside a space ship By Midjourney

It's important to note that food will be combined with water during preparation. If we assume that water can be effectively recycled without loss, we can eliminate most of the water from the food weight to establish the minimum required food mass. Naturally, some water wastage will occur, and initially, food may be stored in more appealing forms than wheat flour or protein powder. For example, if the food was premixed with water, the requirement could rise up to 900 kg/person/year. Nevertheless, water content won’t affect the subsequent energy calculations.

Case 1: feeding the frontiers - food options for pioneer missions

Let's explore food production for a pioneer mission. We have two options: producing it onboard the spacecraft using Controlled Environment Agriculture (CEA), or bringing it from Earth, or a combination of both options. CEA allows precise control of growth conditions like temperature, humidity, fertilizers, and light duration, intensity, and spectrum. Photosynthesis is essential for converting energy into food, just like on Earth. Early NASA experiments favored LEDs in CEA, as sunlight cannot be effectively used in a closed environment of a spaceship.

Photosynthesis efficiency limits the energy conversion from electricity to crop calories. The highest leaf efficiency is currently 4.3%, even for highly productive algae. LED efficiency, at around 50%, also impacts energy demand. To produce food for the Martian crew onboard, they'll need to use 5.63 kW (2,500/0.043/0.5 Calories/day/person) of electricity per person for continuous plant lighting.

Futuristic vertical farm by Midjourney

Since the remaining 95.7% (100% -4.3%) of photons generate heat, a heat pump is needed to maintain a comfortable temperature for both crops and crew. In modern vertical farms, this adds 30% more electricity to the lighting costs, resulting in a 7.3 kW/person power requirement. For a pioneer mission, this means around 45 kW (7.3 x 6)  of power to produce the food only for 6 crew, roughly equivalent to the power consumed by 30 average American households.

To provide some perspective on the numbers: the International Space Station (ISS) can generate up to 240 kW of power at its peak (which means it theoretically can feed 5 Mars missions), but its Integrated Truss Structure (ITS) weighs about 134 metric tonnes, which is responsible for solar power generation as well as thermal and electrical power management.

Which option is more practical: supplying the crew with a potent electricity generator to grow sufficient food using LEDs in addition to other energy needs or equipping them with food reserves for the entire mission? The answer varies depending on the mission's scale.

Modifying the ISS solar power system to cater to the energy requirements of six Martian pioneers would lead to a 25-metric-tonne setup, adding extra weight to the mission. Comparatively, a 45 kWh nuclear power plant might weigh around 6 tonnes. Therefore, for shorter missions, supplying sufficient food reserves from the beginning (at 1.5 tonnes vs 6 tonnes) is more practical. Nonetheless, small-scale onboard farming could remain a feasible alternative for giving astronauts a pleasant experience and access to fresh, nutrient-rich additions to their diet.

Engineering concept of a plant growth module. Credits: NASA/Langley

Case 2: exploring culinary possibilities for a permanent Mars colony

Conversely, for a colony hosting thousands of residents on a continuous basis, it appears more advantageous to produce the majority of the food on-site. To supply the estimated 7.3 MW of electrical power needed for photosynthesis per person, a nuclear very Small Modular Reactor (vSMR) weighing as little as 40 metric tonnes could be utilized. Once delivered, this reactor could meet the colony's annual food demand, which is six times its own weight and could be in operation for decades.

Alternatevly, the colony could rely on solar energy for its power needs. Taking into account energy losses and assuming an insolation on Mars of 1,000 kWh/m2/year, we estimate that a solar power station dedicated to farming would need to occupy an area of at least 250,000 square meters for 1,000 colonists. This at least as large the estimated size of the colony itself, which is estimated to be from 50 000 to 290,000 square meters.

Besides energy, food cultivated in Martian indoor farms will necessitate water, oxygen, carbon dioxide, and an assortment of fertilizers. In the previous article, we outlined the process of extracting water, oxygen, and carbon dioxide from the Martian atmosphere and ice. However, producing fertilizers on Mars poses a greater challenge, as elements like nitrogen are considerably less abundant in Martian regolith and atmosphere compared to Earth. We anticipate that at least several generations of Martian settlers will rely on fertilizer supplies imported from Earth.

Photo by Markus Spiske on Unsplash

Addressing Security and Food Supply Concerns

In addition to energy considerations, the Martian food supply will be influenced by security concerns. While crop failures on Earth can be compensated for by importing agricultural products from other regions, this is not feasible on Mars. The consequences of crop failure due to plant pathogens, power plant malfunctions, or solar flares could lead to starvation among the colonists or necessitate an emergency evacuation. Consequently, even with adequate energy capacity, the transition from reliance on Earth-based supplies to self-sufficient food production will be gradual as the colony expands.

As demonstrated, the issues of energy, security, and food supply are interconnected and must be considered collectively. Presently, astronauts on the ISS are entirely dependent on resupply missions, and farming in orbit primarily serves scientific curiosity. The situation on Mars will be considerably more complex. Before establishing a colony, advanced CEA techniques must be developed on Earth to optimize energy consumption. Current indoor CEA methods, particularly vertical farming, are not capable of sustaining Earth's population due to their reliance on electrical energy.

There are innovative proposals aimed at enhancing efficiency by combining affordable sunlight with CEA, such as the German Space Agency (DLR) project or the Shockingly Fresh initiative. Nonetheless, these projects are tailored for terrestrial farming, and it remains uncertain whether utilizing sunlight on Mars will be viable since plants exposed to sunlight may be susceptible to radiation.

A green house on Mars by Midjourney

We need more advancements in Agricultural Technology for Mars and Earth

Numerous ongoing research efforts aim to boost agricultural productivity and enhance photosynthesis efficiency by up to eight times (for a comprehensive introduction to the subject, refer to Tidal Wave's article). Genetic engineering, for example, enables photosynthesis manipulation or the regulation of circadian rhythms to expedite desired plant growth. Although exotic technologies like cultivated meat or cellular agriculture might appear promising, they either demonstrate lower efficiency or depend on a source of organic materials that must be harvested through photosynthesis.

Unsurprisingly, NASA has backed research in CEA, inspiring numerous startups in the sector. CSS Farms, for instance, employs hydroponic nutrient film techniques in its greenhouses to cultivate seed potatoes for clients. Companies like Plenty and Bowery are also building their vertical farming businesses based on NASA's plant-growth research. In fact, several employees from Bowery, Eden Grow Systems, and Green Sense Farms have previously worked on NASA-funded projects.

Plenty's indoor vertical farming facilities utilize advanced hydroponic systems and LED lighting, which is informed by NASA's plant-growth research. Their technology allows for the efficient production of leafy greens in a controlled environment, providing a potential blueprint for food cultivation in Martian habitats.

Plenty's indoor vertical farming Source: Plenty

Similarly, Bowery has developed its own proprietary vertical farming system, which relies on machine learning algorithms and robotics to optimize plant growth. By employing a data-driven approach, Bowery's system can continuously improve crop yields and reduce the need for manual labor. This type of technology could be crucial in the establishment of Martian agriculture, where human resources may be limited and automation is key.

Both Plenty and Bowery showcase how existing terrestrial agricultural technologies, inspired by NASA's research, can be adapted and applied to the unique challenges of food production on Mars.

Recent advancements in LED technology have rendered vertical farming economically viable for cultivating leafy greens, much like how breakthroughs in lithium batteries facilitated the widespread adoption of smartphones. However, further progress in genetic engineering, photosynthesis, and farm automation is essential to sustainably feed both Earth's and Mars' inhabitants. A vital agricultural revolution is essential for the long-term sustainability of a Martian colony and to feed Earth's growing population in the upcoming decades. Ongoing research and collaboration among space agencies, private enterprises, and academic institutions are imperative for fostering the innovations required for the agricultural transformation that will nourish future generations on both planets.

If you are developing a Food/Agri-tech startup and require our assistance, please do not hesitate to contact us at alexandra@spaceambition.org.