What if we could turn the Red Planet green?

The idea of Mars made verdant with grasses, trees and other Earthly life-forms may sound like science fiction, but at least one small group of scientists and engineers is working to make it a reality. Pioneer Labs, a nonprofit research organization led by CEO Erika DeBenedictis, recently announced what it calls “the first microbe for Mars”: a microorganism adapted to Martian conditions that might someday help humans survive there, too.

Such bioengineered bugs could, in principle, allow astronauts to better “live off the land” on Mars by converting the planet’s raw resources into building materials for habitats, fertilizers for crops, and other products. But the broader vision of Pioneer Labs is far more audacious and fraught: to use biology to help transform Mars into a more habitable and Earth-like world. Terraforming remains a distant and deeply speculative prospect beset by enormous scientific and engineering challenges. It also raises fundamental questions about whether and how humans should ever deliberately unleash Earth life on an alien world.

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Scientific American sat down with DeBenedictis to explore the scientific promise, technical hurdles and ethical dilemmas of sending bioengineered terrestrial microorganisms to Mars. What could such organisms realistically accomplish? How close are we to deploying them beyond Earth? And what obligations do we have to preserve a world where the past or present existence of indigenous life remains uncertain? The answers to these questions could ultimately help shape a larger debate about humanity’s extraterrestrial future—and whether the impulse to make other worlds more like our own should be tempered by any obligation to leave them undisturbed.

[An edited transcript of the interview follows.]

Hey Erika, thanks so much for taking the time to talk. I know you’ve been busy!

Hey! And, yeah, you could say that. On September 22 we announced the first microbe we made for Mars, which was a really cool milestone. It’s a useful and safe thing for us to send to Mars and to use to prepare for the first human mission. It’s the very first step toward this bigger picture—this really inspiring vision of terraforming Mars and making it a habitable, beautiful place.

So this microbe—what’s so special about it, and what exactly is it supposed to do?

What’s cool about it is that we’ve engineered it so that it can directly use the nutrients in Martian regolith, water and processed atmosphere—which is really useful! The idea is that you can go to Mars, and you can feed it dirt, water and air, and use it to build bioplastic houses for astronauts.

Bioplastic?

Yeah. This is a derivative of a terrestrial bacterium called Cupriavidus necator, which naturally produces bioplastic kind of for the same reason that when you eat too many doughnuts, you put on weight in your hips. When this organism has too much carbon around, it creates these big vacuoles of bioplastics, which is a class of materials we’re all familiar with in everyday life. We use them to make everything from compostable cups to 3D printing filament—and that’s essentially how we’d like to make houses on Mars.

So the astronaut houses would have these 3D-printed panels that hold up the structure, and then it would have this plastic lining that holds in the pressure so that you can breathe and that also shields you from radiation.

We’re calling this engineered microbe sPL.001—a special strain made by Pioneer Labs, and the very first of several, in fact. We’ve got plans for four more.

Something to help you build houses seems like a pretty good first step. You mentioned there are more microbes in the works. Presumably they’d do other things—because if we’re trying to build some kind of self-sustaining habitat on Mars, we need obviously more than just big domes made of bioplastic, right?

Absolutely. So let me give you some context first: we’re called Pioneer Labs, and that name is referring to this ecological idea of a pioneer species. On Earth, nature is really good at taking hostile environments—like after a volcanic eruption or a forest fire—and rebuilding a complex ecosystem one step at a time, and the very first steps are executed by really hardy organisms called pioneer species.

They’re often lichens. My favorite, though, is dandelions. They can grow in these really harsh environments, and their presence makes that environment more hospitable for a wider diversity of organisms.

I need to be clear, though: this very first microbe, sPL.001, can’t grow outside on its own on Mars, and that’s important because we don’t want to contaminate Mars accidentally. Yet it’s useful for making these habitats that more stuff can grow in. We think there are four other microorganisms that could complement this first one; altogether we think this could scale up to let us make arable land that’s suitable for agriculture—growing beautiful green plants and making food.

So we’ve talked about this first one for helping to build shelters on Mars. What about the others?

We have candidates for the others now, so nothing is finalized yet, but the idea is each additional microbe type can be another step in this ecological succession for Mars. So consider this a sneak peek.

About half the team is now working on windows. Because if you want to make greenhouses, for instance, you need transparent materials to let the sunlight in. And ideally you’d be able to manufacture those at scale with biology. Imagine growing microbes in a pond that secrete something that floats to the surface, and then you can peel what will become a nice big greenhouse panel right off the top.

And the other half of our team is working on getting rid of the perchlorate in Martian regolith. Perchlorate is a compound that’s poisonous to humans, and there’s so much of it there that Mars dirt can be poisonous to humans, too, as it is now. But there are microbes we’ve found that are able to eat that toxin and degrade it. We’ve found some actually that can eat it directly out of simulated Mars dirt—just add water! So now we just have to push the concentrations up, because Mars has more perchlorate than any organism on Earth has ever experienced naturally. And just like with all our other work, we’re using evolution to try to make an organism that can tolerate it.

Okay. And so the whole idea is that by growing these things locally—by living off the land, so to speak—you’re able to be more efficient and cost-effective, and ultimately self-sustaining, because you don’t have to bring everything from Earth?

Yeah. The reason we haven’t already done a human mission is that humans, with all our radiation shielding and food and so on, are just so heavy. And it’s just so hard to get that much mass to Mars to allow people live for a period of time, and then it’s even harder to bring them back. So it’s incredibly helpful to use resources that are on-site. And indeed, that’s what frontier civilizations have always done.

I want to be upfront about my own biases here: I think this is such a cool idea. But as with pretty much every other aspirational project related to human spaceflight, let alone otherworldly settlement, this one has its critics, too. And I think if I could summarize the sorts of criticisms I’ve seen, it would be three interlinked questions: Why terraforming? Why Mars? And why now?

That is, assuming these bioengineered bugs could also be really useful on Earth, why not just focus your efforts here?

You and I and everyone who’s ever lived is really lucky to live on the one planet we know of that has a functional biosphere. That’s why we’re here breathing, right, because we have a whole planet worth of photosynthesis that’s cranking out oxygen for us all the time. We just call it “nature” and tend to take it for granted.

When we go to space, nature is the one thing that we’re missing. It’s the thing we leave behind when we go away from Earth. Well, I love the biosphere, and I think we should bring it with us. I would love for any future humanity that ventures off into the stars to have more interaction with all sorts of delightful types of life rather than less.

This runs counter to typical visions for the future, I think, where there’s this tendency to think that progress means less nature and fewer trees and we all live in cities with big skyscrapers. That makes me sad, and I don’t think it has to be that way, and so I’m trying to fix it.

Mars specifically is this fascinating world in part because it’s almost like a long-lost twin of Earth. Four billion years ago, both planets had liquid water. And Mars, to this day, even after its climate has been substantially altered, still has all the raw materials for life in abundance in a way that the moon doesn’t and that even Venus doesn’t. Venus doesn’t have a lot of water left, and Mars does—it’s got a whole northern hemisphere that’s permafrost, with huge amounts of buried ice. If only we could warm it up, Mars might become a pretty nice place to live.

And I think that the instinct to go searching outward is just a thing people have. Not everyone wants to be an explorer, but for people who do, Mars is this incredibly intriguing target. And whoever goes first, I’d love for them to have flowers when they live somewhere that’s not Earth.

Flowers on Mars! Maybe it’ll be a dandelion, even.

That would be Pioneer species number six, ha.

Your announcement of sPL.001 made quite a splash, of course. I’m wondering, though, outside of the millions of people who saw your social media post or watched the slick promotional video introducing Pioneer Labs, what the reactions have been from some of your peers in bioengineering, planetary science, astrobiology, and so on. Has it been mixed?

So far, the reaction has been overwhelmingly positive. And I think that’s partially because we took our time preparing for this. We didn’t just announce that we’d engineered the first organism for Mars. We also released a paper showing how we did it, a second paper about a proposed planetary protection framework for thinking about the risks of actually sending such things to Mars and a third paper offering a complete techno-economic analysis for the use cases.

We’ve shown sPL.001 would be extremely dead if it gets outside on Mars, so, in many ways, this is less risky than sending a human complete with a diverse and complex microbiome on her skin and in her gut. And we’ve shown how this could actually be useful, right—not just how to grow the organism but all of the equipment that has to surround it in order to feed it, heat it, purify products from it and actually build houses. We’ve quantified how much all that mass is, how many launches you’d need to get it to Mars and the total footprint it would have.

So we really put our best work into trying to introduce this idea to people in a way that shows why it’s so cool and valuable but also is thoughtful about the ethics. This work has value even if we never terraform Mars. Practically speaking, this is just a good thing to do for the first human mission.

And so—especially on X, where this really went viral—I think there were more people who applauded the fact that we had also released a paper about the ethics than there were people who were like, “Er, we should never go to Mars.”

You’d have to go over on Bluesky to see more of those reactions, I think.

Yeah, exactly.

Let me try to “both sides” this a bit. I want to double down on the very valid point you’re making: if we’re trying to weigh risk and potential impact, landing a single human—or even a single piece of human excrement, let’s say—on Mars, that’s an orders-of-magnitude bigger deal than landing an enclosed bioreactor.

But I also inquired about the reactions of your peers because peer review is important in science, and it’s not clearly something that’s happened for any of those three papers you mentioned. There’s a disclaimer near the end of each one that basically says this has not and will not be submitted for peer-reviewed publication because that goes against the “open science” policy of the Astera Institute, a billionaire-backed nonprofit for incubating transformative science and technology that partly funded the work.

So with that in mind, I have to ask: Who is independently evaluating this stuff? You’re saying that it’s safe to send sPL.001 to Mars, and in the second paper that you mentioned, yes, you’re proposing a protocol for ensuring that nothing bad can happen in terms of biocontamination. But who’s validating these assertions? That seems like a pretty important step in the process, so I’m wondering why you’re skipping it.

My hope is for us to get to share the science we’re doing openly and very quickly. And I should say that we at Pioneer Labs don’t make NASA policy—and that NASA, in fact, isn’t the only organization that makes policy for the whole world, either. There are a lot of discussions that have already been happening about how to update things like planetary protection frameworks for the upcoming new era of human interplanetary spaceflight.

We clearly need new frameworks. Historically, NASA policy has been to stringently sterilize everything that goes to Mars, and you obviously can’t do that for a living human! So we’ve decided to throw our hat in the ring and make suggestions about what that new framework could look like. The goal of the Planetary Protection paper we released is for it to be discussed by COSPAR [the Committee on Space Research], which is the main body that makes policy suggestions to the world. My co-founder Una Nattermann will also be on NASA’s newly convened M-FORCE tiger team, which will make recommendations to COSPAR. Our goal here is to participate in the discussion.

And similarly, we’ve made suggestions about what it could look like to do the first biomanufacturing on Mars. We call this a “reference architecture,” which is a type of paper or engineering document that the space science community often uses. These aren’t usually published in a traditional science journal. I think space science is a discipline that certainly sometimes uses peer review to great effect, but not all of the science happens specifically through journals.

We do currently have funding from the Astera Institute, which believes very strongly that the current peer review journal system is incredibly toxic for science and for innovation. I don’t think anyone really disagrees with that. But as you say, there is this downside to being forced not to participate in traditional journals, which is getting this question about who certifies it. We have, ahead of time, already shared these papers with various colleagues, some of whom are acknowledged in them for the feedback they provided.

Also, there’s no stamp of approval, including from a journal, that means something is definitely right, which means even if we did send it to a journal, that doesn’t mean it’s better. We’re just trying to do the best science we can, and part of the challenge is we have to chart new territory about what it looks like to do this without this kind of crutch of journals dictating what is correct—which we all know to not be true anyway.

I should say the question doesn’t necessarily come from an adversarial place. You’ve stated elsewhere that Pioneer Labs is hopeful to hit the 2031 launch window for Mars. And that’s practically tomorrow, as far as developing a payload and securing a rocket ride is concerned, right? So it would seem in your best interest to try to bring everybody on board, so to speak, as quickly and fully as possible by addressing any significant concerns that exist.

Relatedly, maybe, I wonder if there’s anything you could tell me about what that 2031 mission would notionally look like?

Yeah, I agree. Flight testing is incredibly difficult in terms of the amount of prep that needs to go into it and the magnitude of engineering that needs to go right. That’s even more true for a Mars mission because Mars is so far away. So we’ve released that third paper, the reference architecture, in part because we’re interested to see how the space science community reacts, especially to different possibilities for what the first flight test could look like.

Here’s one example of what the first flight test could be. Wouldn’t it be so cool to go to Mars and do a search-for-life experiment there, where you take a scoop of Mars dirt, you add water, and you incubate it and see if anything grows? Because Mars had nice liquid water back when there was very nascent life on Earth, and there seem to have been giant impacts ping-ponging around the solar system—so maybe one of those impacts sent something to Mars, and maybe today it’s not growing because Mars is too harsh. Maybe it’s dormant in the soil or the ice. One way to find it would be an “enrichment”-type search-for-life experiment. You could sample some dirt or ice, see if it grows anything under more hospitable conditions and do the same after adding fertilizers to see if it’s nutrient-limited.

Now in order to do that experiment correctly, you do need a positive control, so you need to know that your device worked and that stuff can grow in it, and here is where the first microbe we engineered comes in. You could bring sPL.001 as your positive control and confirm that, yes, this organism that’s been carefully selected to die if it gets outside on Mars can in fact grow in a sealed container using the nutrients in Mars dirt.

I think this would be great for everyone. Like, the best-case scenario is you find life on Mars—but even if you don’t, by testing this organism’s growth on Mars you’ve now derisked this big thing that would allow you in the next test to actually use it for engineering and biomanufacturing.

So this is one possible example of a pretty small first step toward deliberately sending terrestrial life to Mars. It’s safer than sending a human. It has some basic science benefit. And it can be scaled up to do things like testing a larger bioreactor—depending on how big a step the space science community feels comfortable taking and which scientific risks we want to address and eliminate.

Speaking of scientific risks, the loudest critics I’ve seen of this work are astrobiologists interested in finding life on Mars who worry that something like sPL.001, if sent there, still poses unacceptable chances for contaminating the planet and irreparably sabotaging the search. Then there’s the more extreme ethical criticism of possible terraforming, perhaps best summarized by the late, great Carl Sagan: “If there is life on Mars…, Mars then belongs to the Martians, even if the Martians are only microbes.”

Yeah, I don’t agree with that second one.

In general, human astronauts on Mars would massively expand our ability and flexibility to search for life. The search for life doesn’t end because you’ve sent humans. Here on Earth, we still go out and look for dinosaur bones even though we already know they’re there. On Mars, the search could and would continue, which reflects something good about humans. We’re curious about our surroundings and we want to know more, and I think that’s something we should encourage.

It’s really complicated, of course, but here are some simple facts to think about. Here on Earth, we have a word for being vegetarian. But we don’t even have a word for trying not to eat microbes, because it’s totally infeasible! There are many different types of life deserving of our respect, but that doesn’t mean a very simple life-form on Mars should unduly eliminate any possible benefit humans could gain by going there.

I think we’re overdue for a big-picture shift in our approach to Mars, which we’ve been treating solely as this object of scientific study, with incredibly strict protocols for what you can send there and how sterile it needs to be—because this isn’t the only relationship that we could have with Mars, right? Like, humanity could live on Mars, and in that scenario, you then have to weigh the potential value of the scientific knowledge of the planet’s history and its former or extant life against the value of humanity having another home.

And just practically speaking, I do think humans are gonna go to Mars someday, so we have to figure out how to do it in a thoughtful way that sets us up for success in living there, as well as in understanding the planet and its history. I don’t think the answer is to get totally tied in knots and paralyzed by the ethics.

That brings me to my final question. You’ve stated in various places that you hope within your lifetime to look up at the little red dot of Mars in Earth’s sky and see that it’s slightly tinged with green—presumably from imported terrestrial life. What do you think is the biggest hurdle to overcome for that? Would it be scientific, technical, political, ethical?

If you had asked me this question two years ago when we began, I would say the biggest hurdle is a technical one. That’s why I was excited to work on sPL.001—because I perceived myself as someone who knows how to solve science problems, and I was looking for a big juicy target to sink my teeth into.

And now when you ask me, I actually do think maybe the hurdle is more social and political in a similar way to how on Earth we struggle to figure out the collective action puzzle of who pays for addressing climate change. Part of why I like working on the Mars case is that I think in some ways it’s much simpler. There’s no NIMBYism on Mars. And I’m hopeful that together, both the technical and the social things that need doing to make humans on Mars happen could be useful right here on Earth, too.