A night sky full of living worlds
A conversation with Astera Resident Edwin Kite on applied planetary science, applied astrobiology, and what it would take to terraform Mars
What does it take to make — and keep — a planet habitable?
For over 50 years, humans have explored space, seeking new homes for life. Life on Mars is the stuff of great science fiction. And the work of actually creating sustainable habitats and ecosystems beyond Earth has, by extension, been a far-flung future. Now, that may be changing.
Edwin Kite is a planetary scientist and current resident at Astera who, together with his team and collaborators, is working on defining a contemporary Mars terraforming research agenda. We spoke with him about what it would take to warm Mars up enough for life to thrive, how open source tools and datasets help research communities build towards the future, and what drives a scientist to investigate how people might create ecosystems beyond Earth.
You’ve been working on Mars science for years. Why this planet?
The biggest unanswered question in Earth science is how and why our planet stayed habitable for life.
For example, for nine-tenths of Earth history, our planet has been uninhabitable for humans: we don’t know why oxygen levels rose.
These are especially interesting questions when you consider that Mars was once habitable, but lost its ability to sustain life. Mars holds a record of that environmental catastrophe, and may hold traces of life that established itself there before that natural disaster. We are in a golden age of Mars science today, with two plutonium-powered rovers on the surface and an international fleet of spacecraft in orbit. We can deeply explore the planet for signs of this record and seek answers to our questions about what happened. It’s a great time to be doing Mars science.
The biggest unanswered question in Earth science is how and why our planet stayed habitable for life.
Understanding what made and what ended Mars’s early habitability can also help us better understand Earth’s history of life and explore the possibility of re-making Mars habitable. Mars has plenty of water and carbon, and its surface receives about as much sunlight as does all of Earth’s land. Sunlight powers almost all of our biosphere, so it’s tantalizing to think of what kind of biosphere sunlight might support in the future on Mars. It’s by coevolution with photosynthetic life that people built cities.
Our ancestors were, in Darwin’s words, hairy forest-dwellers. They moved outwards and built tools like spacesuits and sealskin coats to allow human life in the face of once-unimaginable hazards, like hard vacuum and winter snow. But this approach can only take us so far. Throughout time, space has been forbidding to life, with radiation, micrometeoroids, and cold. If we are going to have an adventure that’s endless, we’ll need to adapt the environment to ourselves. I don’t know how we’ll do this, but the bigger rocky and icy worlds of our solar system seem like a logical place to start. Many are rich in life-essential-volatile elements, all can offer radiation protection, and all have enough gravity to hold onto a stable atmosphere.
What’s the scope of your current project at Astera, focused on terraforming?
It’s been understood for over 50 years that there would be two steps to making Mars more Earth-like: first warm the planet up to allow photosynthesis, which is relatively quick and easy, then build up the oxygen level using photosynthesis. We’re looking at the first step, surface warming.
Mars is too cold for stable liquid water — the average temperature is around 210 K (about -60º C), and atmospheric pressure is only ~6 millibars. Warming the planet by 30 – 50°C could melt near-surface ice, enabling surface habitability and photosynthesis. There are lots of ways to warm Mars, including greenhouse gases and orbiting mirrors. Our team at Astera is investigating a warming approach based on engineered aerosols — specifically, nanoparticles that can forward-scatter sunlight and block thermal infrared. Compared to greenhouse gases, they’re four orders of magnitude more mass-efficient. That kind of efficiency matters — you want to get the biggest radiative payoff. If we want to make progress in this century, we need to use the materials that are already readily available on Mars, rather than shipping them in.
Along with the simulation work and delivery prototyping that we’re doing at Astera, we are working with collaborators at Northwestern University to batch-manufacture and test the most promising particles. This work is part of an extended collaboration involving scientists from Aeolis Research, JPL, the University of Central Florida, MIT Haystack Observatory, and the University of Chicago Climate Systems Engineering Initiative, among other institutions.
What properties of aerosols lead to warming the planet, rather than cooling it?
On a clear-sky night when we can see the stars, it's typically cooler than on a cloudy night. So clouds (a form of aerosol) act as a warm blanket. Clouds also bounce sunlight back to space (cooling effect). For any aerosol, the net effect (warming minus cooling) depends on the size, shape, and composition of the aerosol. To warm Mars, we need to choose/design a combination of size, shape, and composition that gives a strong warming effect.
We also need to pay attention to particle mass. In our recent Science Advances paper, we showed that certain nanoparticle designs can achieve the same warming effect as fluorocarbon gases (a particularly potent greenhouse gas), but with ~50,000 times less mass. That matters, because even with the improved launch economics we’re seeing, getting mass to Mars is still expensive, so we need to keep the particle factory as lightweight as possible.
How would these nanoparticles be made?
The current concept involves dispersing nanoparticles into Mars’ atmosphere, where they remain aloft for long periods. These particles — which could include graphene disks or metal ribbons or even natural salts — selectively scatter shortwave solar radiation while blocking outgoing infrared. This alters the radiative balance, raising surface temperatures.
We’re exploring multiple production pathways. For example, it may be possible to fabricate aerosols using materials from Mars regolith, or using Mars’ CO2-rich air as the feedstock for making graphene disks as a byproduct of oxygen production. For a solar-powered graphene production, the basic ingredients for warming Mars could be Mars’ air and sunlight.
Particles also have another advantage: they start working within months and stop working when removed. That makes the system controllable and potentially reversible. So we could switch off or adjust a well-designed intervention as warming proceeds.
We hear your team has already made advances on researching particles 👀
Yes! One of our researchers, Alex Kling, developed an open-source screening tool to assess the warming efficiency of different particle types. It’s motivated in part by a conversation at the Tenth Mars conference, where Mars climate researchers agreed we needed something like this for natural aerosols as well. And I hope it will also be used by exoplanet researchers. Natural aerosols can be really important in extending the habitable zone, in both warming and cooling directions (for example, the type of high altitude organic haze found on Saturn's moon Titan can be really effective in cooling a world's surface).
Our tool is already available on GitHub, and it’s forming the basis for our next set of experiments. You can find it here:
We’re also going to batch-manufacture and test particle interactions and production protocols — essentially, answer questions like, how hard is it to make these materials from scratch? What kinds of impurities or degradation modes do we need to model? And we’ll continue sharing our results openly through preprints, on Zenodo, and on Substack.
Why is it important to do this work as open science?
Making all our findings public is necessary for informing a spacefarer’s consensus about what to do with those findings. The Outer Space Treaty says, “The exploration and use of outer space [...] shall be the province of all humankind,” and every country has signed up to that.
Because we’re starting a new field, we have to work in a way that others can plug into. We have to seed open standards, protocols, and cultural momentum now, to create infrastructure that enables many organizations to work on terraforming in parallel. We’re building tools, datasets, and protocols that others can test, benchmark against, and improve. That includes publishing aerosol designs, experimental methods, and model inter-comparison frameworks — both the successes and the failures. We need to create a foundation that the whole research community can build on. And culturally, this aligns with NASA’s approach — raw rover images are public as soon as they arrive — and it’s a model that’s worked well for decades.
How do you think about the ethical questions that arise from a proposal to terraform Mars?
Perhaps Mars should remain untouched, as a planet-sized wilderness park that people bypass on our way to the stars? Or we could see Mars as an environmental restoration problem: undoing the collapse of a once-habitable planet?
Personally, I think a night sky full of living worlds is better than one that’s dead. Mars is Galactic gardening for beginners. If Mars is lifeless, then there’s no ecosystem to protect, and creating a new one might be the most meaningful thing we could do with it. But more work is needed to search for life on Mars, and decisions about Mars’ future should be made within a democratic framework. Any serious terraforming effort would take decades, if not centuries. On those long timescales, our politics and our worldviews will change. What won’t change are the basic scientific constraints, and it’s the science that we propose to study.
How can people learn more?
You can read the essay with Robin Wordsworth or check out our latest technical study. And keep an eye out for our forthcoming technical Substack!