Last month Erika DeBenedictis, CEO of the nonprofit start-up Pioneer Labs, delighted or shocked many space nerds with some big news: she and her colleagues had engineered “the first microbe for Mars.”
In a post on X that has garnered more than two million views, DeBenedictis claimed that her bacterium, a tweaked version of Cupriavidus necator, represents “the first step towards terraforming” the Red Planet. By seeding Mars with microbial life, she has argued, we can make the world more Earthlike from the ground up.
“Everything life needs to thrive is given to us by nature,” observed DeBenedictis, a synthetic biologist with a Ph.D. from the Massachusetts Institute of Technology, in a slick promotional video that was included with the post. “When humanity goes to space, we have to bring nature with us.” The clip teased a future Mars with green valleys and self-sufficient, see-through, domed habitats, all constructed with locally sourced materials, some of them courtesy of the microbe, which DeBenedictis and Pioneer Labs call “sPL.001.”
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It’s certainly a compelling story. And it’s backed up with a few recent preprint papers detailing Pioneer Labs’ research. But how much of it is fantasy?
Scientific American put that question to several researchers working at the intersection of planetary science, astrobiology, microbial ecology and bioengineering—and their responses are, on the whole, fairly positive. The most critical assessment comes from Chris McKay, a planetary scientist at NASA’s Ames Research Center, who has studied terraforming for decades. McKay is senior author of “The Case for Mars Terraforming Research,” a paper led by DeBenedictis that was published last year in Nature Astronomy. The engineered bacterium is “not very interesting, not very new yet,” he says. “I hope better is coming soon.” Paul Race, who studies industrial biotechnology at Newcastle University in England, offers the same impression, calling the announcement “rather over the top.”
Their core qualm is that this microbe alone can’t bring a dead planet to life. “This microorganism, sPL.001, is not for terraforming Mars—it’s for making feedstock for 3D-printed houses,” McKay says. “It can only be grown in a bioreactor,” an apparatus for incubating microbes, such as yeast, to yield useful by-products. DeBenedictis’s microbe would pump out a form of bioplastic by consuming Martian dirt, water and compressed carbon dioxide delivered to the bioreactor with autonomous machinery. To her credit, DeBenedictis has been clear on this point: sPL.001 “is the first of five organisms we will need to make Mars green,” she wrote in an post on Pioneer Labs’ Substack.
“Hopefully,” McKay says, “some of the other four are green and can actually grow on Mars!”
A workbench at Pioneer Labs’ headquarters in Emeryville, California. This equipment uses robotics for high-throughput characterization of evolved microbes in search of ones suitable for Martian environments.
Elijah Collins/Pioneer Labs
DeBenedictis founded Pioneer Labs in 2024, when she was a resident at the San Francisco Bay Area–based Astera Institute, a billionaire-backed nonprofit focused on incubating science and technology projects with ambitious long-term visions (and correspondingly ambitious needs for sustained funding). The company’s name, DeBenedictis says, comes from the ecological idea of “pioneer species” that colonize barren territory as a first step for the creation of complex ecosystems. And its stated goal is no small thing: to make the universe more friendly to life.
On Earth, pioneer species are usually organisms we think of as weeds or pests that can tolerate the harshest environments: molds that feast on decaying organic matter, lichens that thrive almost anywhere or dandelions that grow in and break up rock to make and enrich soil. They’re not glamorous, but they allow “fancier organisms and shrubs and trees and stuff to grow, and that’s exactly what we’re trying to do” for Mars, DeBenedictis tells Scientific American.
Bootstrapping a biosphere there isn’t easy, however. Biology is bedeviled on the planet, exposed as it is to unrelenting harmful radiation and given its paltry atmosphere, 1 percent as thick as Earth’s, and temperatures that, in a single Martian day, can swing violently by 100 degrees Celsius. The low levels of nitrogen in the atmosphere and in the ground add insult to injury—a 2025 review paper in Communications Biology noted that a lack of nitrogen is “a major limiting factor for establishing Earth-like organisms or supporting human agriculture, and limits our capacity to terraform the planet.” Plus, some samples of Martian soil contain high levels of perchlorates, toxic chemical compounds, also found in rocket fuel, that could potentially poison the planet’s supplies of water and food.
“We need to choose carefully” when we devise bioengineered microbes to overcome these immense challenges, DeBenedictis says.
Neveda Naz, an astrobiologist at Tufts University, who has grown microbes in material from Martian meteors, says Pioneer Labs had done just that with its focus on the bioplastic-producing version of C. necator. “They have picked an organism, adapted it to a defined Mars-relevant chemical environment and demonstrated improved production of a useful material,” Naz says. “If the goal is eventually to manufacture materials off-Earth using predominantly local resources rather than transporting everything from Earth, that’s a very worthwhile and smart direction to explore.”
Alexandre Rosado, a microbiologist who has studied terraforming and focuses on ultrahardy microbes called extremophiles, agrees. “I think the work is interesting, and there is certainly good science there,” he says. “I would not dismiss it. My view is that microbes will almost certainly be part of any serious attempt to use local Martian resources or, much further down the road, modify Martian environments.”
Both Naz and Rosado, however, quibble with Pioneer Labs’ declaration that this makes the modified C. necator a “microbe for Mars.” For Rosado, the company’s language around terraforming “goes quite a bit beyond what they have actually demonstrated.” And, Naz says, “there is an important distinction between showing that Martian regolith can provide biologically useful nutrients and showing that an organism can grow in the Martian environment.”
DeBenedictis is aware of the distinction—it’s the centerpiece of Pioneer Labs’ safety strategy for avoiding potentially ruinous interplanetary contamination, PRIM (Propagation Restricted, Inert on Mars). In her team’s experiments, the researchers found that C. necator failed to reproduce if it was starved of water and carbon. So, she says, if the microbe somehow escaped a bioreactor on Mars, its chances of survival and reproduction would be infinitesimal. “Even a full, catastrophic leak of an industrial-scale Mars bioreactor would still clear the planetary protection threshold by a factor of several hundred,” DeBenedictis says. “I’m genuinely not worried about it.”
Whether policymakers who set international standards for “planetary protection” protocols won’t worry about it, either, is another hazy aspect of Pioneer Labs’ hopeful aspirations. Without regulatory approval, DeBenedictis’s best-laid plans for helping to terraform Mars may literally fail to launch. As NASA administrator Jared Isaacman noted on X, however, his team has been working to revise the space agency’s protection policies to align them with what he calls the “common-sense principles” originally established in the “early days of planetary exploration and later reflected in Article IX of the Outer Space Treaty.” He thinks current protection policies needlessly add “extreme cost and time to robotic missions to Mars when the overarching goal is to send astronauts there as quickly and safely as possible.”
Ricard Solé, a biologist who heads the Complex Systems Lab at Pompeu Fabra University in Barcelona and studies, among other things, terraforming via bioengineered ecosystems, thinks PRIM is on point. “It separates useful biotechnology from uncontrolled ecological spread,” he says. “Pioneer Labs’ proposal is a very interesting and important step, but if the goal is eventually to build a stable, closed ecology on Mars, then a systems-level perspective will be essential.” Mars will need more than “a single engineered strain,” Solé says, envisioning a larger assemblage of multispecies communities that collectively recycle matter, turn one organism’s waste into another’s resource, regulate environmental conditions, and so on. “In that sense,” he says, “the challenge is not only to engineer organisms but to engineer the ecological interactions that allow the whole system to sustain itself.”
This is where DeBenedictis’s as-yet-unannounced four other microbes come in. They have yet to be revealed, she says, because Pioneer Labs hasn’t entirely settled on which organisms could do the job. Whichever ones win the day will have to offer “transparent building materials, perchlorate reduction, making fertile soil, and then food and oxygen,” she says. The transparent material, crucial for making windows, will be the hardest to find, she speculates. “We don’t have very many examples of biomaterials that are transparent when they’re dry, which is what you need on Mars because the atmosphere outside will dry anything out, so we’ll see what we come up with.”
If all goes to plan, she thinks, the effect will be to transform the night sky by a significant smidge. “You can see Mars outside with your naked eye, and it’s noticeably a little red relative to other stars in the background,” she says. “And I think, before I die, I’ll get to see it be a little bit green.”