Scientists Have Developed a Breakthrough Energy Source to Fuel the First Humans on Mars

5 min readResearchers proved that certain food-grade plastic can be broken down and fed to engineered yeast, which then produce nutrients such as protein and fats. Researchers turned the result into a protein-rich “cookie.”This cookie-making method might be headed for Mars missions, as NASA plans to send astronauts to the Moon and then farther into the Solar System.Other substances have been successfully made using yeast feeding on plastic, such as drugs for Parkinson’s. But many kinds of results are possible—even a plastic-derived beer.When the first humans set foot on Mars, no doubt they’ll have plenty of equipment for research projects. But every human endeavor requires food, and the Red Planet is seriously lacking. Unfortunately, astronauts can’t bring all of their food with them, because it would be too heavy; instead, they need to carry the means to make food themselves. In one scenario, they might set up bioreactors, bins of plastic waste, and genetically engineered yeast, then break down the plastic into its tiniest constituent pieces and feed it to the yeast. What comes next may sound bizarre, but it’s a proven food-making system that researchers at Southern Illinois University Carbondale have already designed.In a first, these scientists have demonstrated that plastic waste can be processed into edible, nutritious compounds for astronauts. One day, the breakthrough could also help feed people on Earth in situations where food is hard to find, such as after a natural disaster, or in remote areas, such as a polar research station or on a submarine.The solution starts with the 400 million tons of plastic waste that we create each year and ends with a protein-rich cookie that’s theoretically good enough to eat. The research team described its method in the peer-reviewed journal Trends in Biotechnology.Microbiologist Lahiru Jayakody, PhD, an associate professor and head of the plastic cookie research at Carbondale, says a lot of people misunderstand how food can be sourced from plastic. He likens the process he and his team engineered to drinking milk from a cow. Drinking milk doesn’t mean you’re also consuming grass, just because it’s what the cow ate; instead, grass was the raw material that helped the cow power its ability to make milk. While you can’t digest grass, you’re still benefiting from the natural biochemical process that the cow’s preferred food has already kick-started. In the same way, plastic compounds the yeast consume do not end up in the final cookie, so it’s safe to eat.To make an edible cookie using plastic and microbes, the team first had to deconstruct polyethylene terephthalate, or PET, which is widely used for water bottles and other food packaging. PET is an ideal plastic source because it avoids the dangers of toxins, such as heavy metals, and PFAS, or synthetic “forever” chemicals that can build up in our bodies. So, while it’s tempting to think we could eliminate all kinds of plastic waste, it wouldn’t be safe to, say, pick up random trash from a landfill to turn into protein cookies. Perhaps more types of plastic could be used in the future, but it would require a lot more research to get there, Jayakody says.Next, the PET waste is exposed to water and oxygen in an environment that’s like a toasty oven at about 482 to 536 degrees Fahrenheit, and that mimics the crushing pressure found more than one mile below sea level (about 2,000 psi). These conditions cause PET to fragment into carbon-rich, organic compounds. Unlike some other processes that break down plastics, this method doesn’t require an expensive catalyst or hazardous solvents, and there are no toxic byproducts.Then, the researchers added yeast cells and fed them a liquid combination made from broken-down PET compounds and agricultural byproducts, such as cornstalks. The yeast, genetically engineered to love this carbon feast, broke it down even more, metabolizing and rebuilding the compounds into simpler molecules such as lipids (which include fats), acids, proteins, and vitamins.The resulting stuff wasn’t appealing enough to eat, but the team took this mixture and added sweetener, fiber, and starch. “We’re introducing food additives, like vanillin [synthetic vanilla] and beta carotene to add color to this cookie, to make it more vibrant in texture, flavor, and appearance,” says Sandhya Jayasekara, a graduate research assistant and doctoral candidate at Carbondale. Using a 3D printer, researchers extruded the dough-like concoction into a round cookie with the Greek symbol “µ” in the center, to symbolize its name, the “µBite,” or microbite.Once early safety tests determined that the cookies were edible and safe to eat, researchers conducted a human sensory analysis—without physically tasting them—under the expert authority of SIU’s Fermentation Science Institute. Now the team is seeking clearance from the U.S. Food and Drug Administration for human taste trials.Russell Bailey, SIU CarbondaleA 3D printed “μBite” (microbite) cookie could be a protein-rich food source for astronauts on long missions. NASA hopes it will help feed people on Mars, and it could also supplement diets where food is scarce here on Earth.For space missions, a compact bioreactor and a 3D printer could fit on a spacecraft and provide three astronauts with their daily protein requirements, Jayakody says. For now, researchers are working to refine their process for NASA as part of its Deep Space Food Challenge in anticipation of sending humans to the moon by 2030 and then to Mars.While Jayakody’s team is the only one so far to turn plastic waste into edible substances, other researchers have been feeding plastic to bacteria and churning out valuable medicinal compounds. For example, scientists at the University of Edinburgh used genetically altered E. coli bacteria to turn PET into L-DOPA, an important medication that treats Parkinson’s disease.From a conservation standpoint, microbite cookies, drugs, and other products made of plastic will not put a significant dent in the 56 million tons of PET waste we produce annually, says Jason Hallett, PhD, a professor of sustainable chemical technology at Imperial College London, where he researches how to transform plastic into new materials as well as how to scale up laboratory designs for practical use. The bioreactor would need to be impractically large, he says, and engineering microbes to make food is expensive, he says. Hallett is not affiliated with the Southern Illinois University team’s work.To make it a real solution for feeding large groups of people on Earth wherever there’s a food shortage, the bioreactor would need to prove itself at 100 liters of volume—and later, its capacity would need to mushroom to 1,000 liters. Instead of producing enough material for just a few cookies, a scaled-up version could churn out about 220 pounds or more for each run of the reactor, Jayakody says.Still, investigating how to grow food in a laboratory is a great idea, Hallett says. If we make more protein in bioreactors, we won’t have to devote so much energy and land to large-scale animal farming. It’s also a potential ethical alternative to farming animals for food and for reducing carbon dioxide emissions tied to livestock farming, he says.Plastic garbage and global hunger are still massive problems, but with researchers looking at plastic waste from a microbe’s point of view, they might unlock unconventional solutions.And, if all else fails, microbes could be used to create something purely for fun: “One of my dreams is making beer with plastic,” Jayakody says, laughing. “It’s not impossible to do.”Before joining Popular Mechanics in 2022, Manasee Wagh worked as a science journalist, a newspaper reporter, a technical writer, and an engineer. She has a bachelor's degree in computer engineering and a master’s degree in journalism. Her favorite stories are about the discoveries that unearth even deeper mysteries, and she enjoys helping people understand the science behind the remarkable world we live in. She lives in the Northeast with her two favorite people and one curious, feisty feline, but always seeks to combine her love of food, nature, and travel into memorable journeys away from home.