In a groundbreaking study, researchers propose using carbon-rich asteroids as a source of edible biomass for long-term space travelers. By converting the hydrocarbons present in asteroids into edible biomass, future space missions could theoretically produce enough food to sustain astronauts without relying on Earth-based supply chains. At least, that’s the theory.

We don’t really have a viable plan for long-term space travel.

Currently, missions to the International Space Station and potential missions to Mars depend heavily on resupply from Earth, which is costly and logistically complicated. For a mission on Mars, food alone could weigh about 12 tons — an immense burden considering the cost of launching supplies into space. SpaceX, for instance, estimates a cost of around $2,720 per kilogram for sending payloads into orbit, let alone more distant shipping.

“Farming in space, on an external base, may be possible but is extremely complex,” write the researchers, led by Eric Pilles from the Institute for Earth and Space Exploration. Some options exist (like the hydroponic plant systems on the ISS), but they are not mature and require significant initial input from Earth. If we want a long-term space mission, we need better ways to get food.

A new study suggests an unexpected alternative: space rocks.

Organic substances in asteroids

The researchers based their study on a specific type of asteroid called carbonaceous chondrites, which contain large quantities of organic compounds, including hydrocarbons.

These asteroids contain complex organic compounds. By exposing these compounds to specific microbial communities, we could potentially convert them into human-edible food. The pyrolysis process — using high heat to break down these materials — could produce hydrocarbons that microbes can consume, which would, in turn, produce food.

There’s no shortage of these asteroids in the solar system. They’re abundant in the outer reaches of the asteroid belt, and many of them hold both water and organic molecules — resources crucial for both life and propulsion in space. Carbonaceous chondrites, like the asteroid Bennu, contain up to 10.5% water and substantial amounts of organic matter.

How would this work?

The central idea is to break down hydrocarbons on these asteroids into simpler, edible compounds through microbial processes. Essentially, special bacteria would consume the asteroids and produce edible biomass.

This method draws inspiration from Earth-based technologies designed to recycle plastic waste into food. In fact, groups of anaerobic bacteria (groups of bacteria that can break down compounds in oxygen-free environments) could be employed to metabolize the organic materials found on asteroids.

The idea is not entirely new. DARPA researchers have been working on something similar. They have tested plastic containers as food for microbes that grow biomass. The new work estimates how much food we could derive from an asteroid like Bennu (which has been extensively studied). The researchers propose two scenarios: a minimum scenario where only aliphatic hydrocarbons are converted into food, and a maximum scenario where all insoluble organic matter is used.

Their estimates found that such an asteroid could provide anywhere between 600 and 17,000 astronaut life years. The lower estimates suggest around 50 metric tons of food, while the higher ones add up to 6,550 metric tons of edible biomass. This is a game changer for long-term space travel (with the big caveat of how this asteroid can actually be mined).

Can this actually work?

The implications of this research are profound. If asteroid mining for food becomes a reality, it could revolutionize how we think about long-term space missions. Instead of sending enormous quantities of food from Earth, astronauts could rely on locally sourced food from asteroids. It would open the door to more ambitious missions, such as establishing permanent human outposts on other planets or moons, where asteroid mining could be a key part of the life support system. But it’s unlikely to happen anytime soon.

For now, we’re pretty far from this level of technology. But, researchers are working on it.

Mining asteroids for food would also dovetail with other in-situ resource utilization (ISRU) technologies under development for space exploration. ISRU focuses on using local materials to meet human needs in space, from creating breathable oxygen and water to manufacturing fuel and building materials. Adding food production to the ISRU toolkit could be the final piece in making long-duration space missions truly self-sufficient.

Another challenge is developing the necessary infrastructure to mine asteroids and process the organic materials. Mining asteroids would require sophisticated robotics. Then, processing the materials into food would involve bioreactors capable of supporting microbial life in space. The cost of developing and deploying these technologies could be significant, though the potential benefits make it a worthwhile pursuit.

Future research will also need to address the scalability of the process. While the theoretical calculations suggest that significant amounts of food could be produced from a single asteroid, practical considerations such as production rate and energy requirements for the process will need some careful evaluation. And then, the resulting food also has to be tested extensively to ensure it’s fit for consumption and palatable.

Despite these challenges, the prospect of mining asteroids for food represents a bold and exciting frontier in space exploration. You may think there’s nothing we can use out there, in space, but scientists are increasingly showing that our solar system is rich in all sorts of resources. Whether we can use these resources, however, is a different challenge.

Journal Reference: More information: Eric Pilles et al, How we can mine asteroids for space food, International Journal of Astrobiology (2024). DOI: 10.1017/S1473550424000119