Algae transformed Earth. Next stop: Mars?

Tiny Matters

Since the very beginning of the space age, people have been wondering if algae could provide a life support system beyond our planet. From dozens of studies over the last 60 years, we’ve figured out that algae probably can thrive for up to a year in space. But what if we wanted to live permanently on another planet, like Mars? This episode is all about algae: how it shaped early Earth, how we might use it to terraform planets in the future, and how it’s being used in biomanufacturing to hopefully get us away from relying on fossil fuels.

Transcript of this Episode

Sam Jones: Since the very beginning of the space age, people have been wondering if algae could provide a life support system beyond our planet, pulling CO2 from the air, helping with water recycling and even food production. In 1960, algae was flown into space for the first time, aboard a Soviet spacecraft, which was only the fifth satellite to ever be launched into space. And over the last 60 years, we’ve continued to run experiments in space and on Earth to figure out how likely it is that algae could sustain us.

Deboki Chakravarti: And from dozens of studies we’ve figured out that algae probably can thrive for up to a year in space. But we’re talking about space crafts. What if we wanted to live permanently on another planet, like Mars?

Deboki: Welcome to Tiny Matters. I’m Deboki Chakravarti and I’m joined by my cohost Sam Jones. Today’s episode is all about algae: how it played an essential role in early Earth, how we might be able to use it to terraform planets in the future, and how it’s already being used in the biotech space to hopefully help us make the present, as well as future, more sustainable. This episode idea was suggested by one of our listeners, Chris Fisher, so thank you Chris.

Sam: So, like we often do on Tiny Matters, we’ll start with the basics. Algae are plant-like organisms that are primarily found in aquatic ecosystems and are super diverse. Some algae are single-celled and others are multicellular, like seaweeds and kelp. They are very, very important primary producers at the base of the food web. By using the process of photosynthesis, they convert carbon dioxide and water into oxygen and glucose—or food—all by absorbing light energy from the sun using the pigment chlorophyll.

Algae are essential for the survival of many marine ecosystems and those marine ecosystems are important for the survival of many terrestrial ecosystems and… you probably get where I’m going: on this planet, we are very reliant on algae. And if we’re hoping to survive on other planets, it’s looking like we’ll probably need algae—or something very similar to algae—as well.  

Deboki: Current life support systems, such as the Life Support Rack on the International Space Station, capture carbon dioxide from the cabin air but they only recover about 50% of its oxygen for the astronauts to use. And that’s not a problem because the ISS is quite close to Earth so we can replenish. But as humans travel farther away from Earth for longer periods of time, or possibly forever, we will need to have an ongoing source of food and fresh water and oxygen.

Sam: So let’s say humans do make it to Mars and now we’re gonna try to get algae to grow and sustain us. Is that a totally ridiculous plan? We reached out to geochemist Jochen Brocks at Australian National University, and he told us no, it’s not completely ridiculous.

Jochen Brocks: We know that the soil on Mars has all the nutrients that they need. So we know we have created artificial mars soil and cyanobacteria and algae grow just fine on it. The sun is also there. So what's really missing is the atmosphere. Mars has more than 95% CO2 and 3% nitrogen, but the total pressure is 100 times lower than on Earth.

Sam: So Mars’s soil composition: check. The elements in the atmosphere: semi-check, not ideal because algae’s used to our atmosphere which is around 78% nitrogen. But the biggest issue is the atmospheric pressure. Because it makes it hard for the algae and other oxygen-producing microbes we’re interested in called cyanobacteria to fix nitrogen.

Nitrogen fixation is a process where nitrogen in the atmosphere is converted into other nitrogen compounds that are super important for a bunch of biological processes and even to the structure of DNA itself. Under really low pressure, algae has trouble fixing nitrogen and it can’t grow. Plus, Jochen pointed out, Mars doesn’t have water. That’s a big problem for aquatic organisms like algae. But, he said, if you could create a lake on Mars and have a station with a higher pressure atmosphere that’s a bit more similar to Earth’s then you could probably get algae and cyanobacteria to grow anywhere.

Deboki: The idea of bringing cyanobacteria and algae to space is very cool, although we don’t know yet how to make that happen or what it will look like if we do bring these organisms to Mars. But we don’t have to look far to find a planet that’s been transformed by them. We’ve got Earth. So, although we started off the episode by looking toward the future, now let’s look back. Way, way back.

Sam: And as we travel back to early Earth, we want to make an important clarification about cyanobacteria right up front. You’ve likely seen them referred to as “blue green algae.” They are not algae, they are bacteria. The term is very misleading. We’re bringing them up because cyanobacteria, along with algae, were such an important part of transforming Earth.

Deboki: Ok so. Our planet—Earth—is around 4.6 billion years old. And it looked very different back then from how it looks now.

Jochen Brocks: The atmosphere was mostly nitrogen, there was CO2, there was probably methane. And then we get the first signals in the geological record that oxygen appeared around 2.4 billion years ago. You can recognize this most nicely in red rocks appearing, rusted rocks, sediments with a red color. Rust is iron III, it was formed by the oxidation of iron II. Before 2.4 we don't see these types of red colored rocks. And suddenly they start appearing. And the only way to make that oxygen is photosynthetic bacteria, cyanobacteria.

Deboki: When oxygen started filling the atmosphere, it allowed for tons of new life forms—eventually us—to exist. But that shift was at the expense of organisms that didn’t use oxygen, called anaerobic organisms.

Jochen Brocks: Oxygen, although we need it, is extremely toxic to everything that's anaerobic, extremely toxic. One of the most toxic gasses. And it was probably one of the biggest mass extinctions in Earth’s history when cyanobacteria started making oxygen,  probably causing a huge extermination of organisms on the surface.

Deboki: Those organisms on the surface were probably things like bacteria that had been living without oxygen or with very little oxygen for millions, maybe over a billion years. And when we talk about cyanobacteria and algae creating oxygen in the atmosphere it’s not that they physically produce tons of oxygen, it’s that they’re splitting the CO2 in our atmosphere into its parts—carbon and oxygen—and then absorbing the carbon, leaving us with oxygen.

Sam: Jochen told us that cyanobacteria coming in and oxygenating the atmosphere billions of years ago was kind of like if an organism showed up today that could take up the chlorine in the ocean and release it as chlorine gas. Chlorine is a component of salt, aka sodium chloride, so you can imagine if there were an organism that could grab that chlorine and then shoot it into the air as chlorine gas it would be very bad for us humans and a lot of other organisms.

Jochen Brocks:
So the oxygen created by the cyanobacteria did a lot of amazing things that changed the surface of the planet that changed the rocks that we find. The most important thing they did is they started to oxidize methane in the atmosphere.

Deboki: Methane, like CO2, is a greenhouse gas. Having a bunch of methane in the atmosphere was keeping Earth quite warm. Once oxygen started replacing methane, things began to cool off. And that became a big problem, because billions of years ago the sun wasn’t as strong as it is today.

Jochen Brocks:
If you go back three and a half billion years, or two and a half billion years, the sun was so cold that actually the entire planet should have been frozen over already in the beginning, but it did not. And the best explanation for that is that there was a lot of methane gas in the atmosphere because methane is about 30 times more potent as a greenhouse gas than CO2. So we believe that before 2.4 billion, there was a lot of methane in the atmosphere. And then the greenhouse gas levels start dropping, dropping, dropping, and it's getting colder and colder and colder and the planet plunged into an ice age. So that’s the first snowball earth that happened around 2.3 billion years ago.

And the entire planet was presumably frozen over. There's not many rocks left of that time, so we can't be really sure where the glaciers were, but the most extreme idea is the glaciers reached all the way to the equator, the entire planet was frozen over and the water at the equator was frozen two kilometers deep. So it was really like the Moon Europa. It was just a snowball of frozen ice, and that's a direct consequence of cyanobacteria making oxygen.

Deboki: So now let’s shift gears slightly to talk a bit more about the very important thing that algae do: photosynthesis. We briefly summarized it earlier, but it’s not as simple as using light to convert carbon dioxide and water to oxygen and food. To find out more, we chatted with molecular biologist Tanai Cardona at Imperial College London who has spent his career thinking about photosynthesis and its early beginnings, which brought him to study algae as well as cyanobacteria.

Tanai Cardona: When I was an undergrad student maybe 20 years ago, I learned about the molecular complexes inside the algae that enabled the photosynthetic process. They're very complex. They're loaded with chlorophylls and they are very unique in many ways.

Sam: To illustrate that complexity, Tanai told us that when some cyanobacteria find themselves in an environment where there’s no visible light, only far red light at the extreme end of the visible spectrum, these cyanobacteria are able to produce a different type of chlorophyll so that they can continue to use photosynthesis.

Tanai Cardona: and there are many other types of adaptations that bacteria has, but then in more complex algae and plants, there are also interesting adaptations of their own that specialize to different types of environment as well.

Tanai Cardona: the diversity of what photosynthesis can do, particularly in cyanobacteria, is something that we are only just starting to understand.

Deboki to Tanai: So a lot of times I think when people think about photosynthesis, a lot of us think about trees, we think about plants, we think about the things we could see all the time. So if you were trying to explain to someone the importance of algae in all of this, in our life and in our world, what would you tell them?

Tanai Cardona: Algae, and bacteria as well, contribute substantially to primary production. In terrestrial environments, but also in aquatic environments and in the oceans, both cyanobacteria and the microbial algae that we are perhaps less familiar with, could produce half or more of the oxygen that we breathe.

Sam: So we asked Tanai, what would happen if all of a sudden algae ceased to exist? He told us it would be catastrophic. But then he took that mental exercise one step further and asked, what if there were no photosynthetic organisms at all?

Tanai Cardona: Society would collapse very quickly because there would be no food, there would be no crops. And eventually, most animals will not have anything to eat. All of the complex life on Earth will be the first to go.

More than 99% of the entire biosphere depends on photosynthesis, oxygenic photosynthesis. So if w e eliminate photosynthesis, eventually we will have a barren world, where only there will be perhaps clusters of life representing perhaps less than 1% of what we have now in some very unique environments, perhaps in hydrothermal vents, deep in the ocean.

But then all of the beauty of the world will disappear eventually, and all of the oxygen will go away. And so earth will kind of return to its primordial state perhaps of 4 billion years ago.

Deboki to Tanai: I'm so curious, based on what you're describing, you're talking about us returning to this primordial state of Earth. Do you have an idea or a guess about how long you would think it would take to evolve photosynthesis again from that?

Tanai Cardona: Well, that's interesting because it links to my research. I spent a great deal of my career as a scientist trying to understand how photosynthesis evolved and originated. And from my research, I would argue that it does not necessarily need to take a long time. So I think it could be surprisingly fast. The current paradigm is that life emerges in the absence of photosynthesis. There could be hundreds of millions of years, if not a billion years before the first type of photosynthetic organisms emerge. And they would not have the capacity to produce oxygen.

So this is what we call anoxygenic photosynthesis. And it is usually thought to be a type of primitive photosynthesis, and it only occurs in some types of bacteria. And then it could be hundreds of millions of years more for oxygenic photosynthesis to appear. But I have challenged this timeline, and I've been arguing that actually when we look at the photosynthetic machinery, the one that is doing oxygen production seems to retain many, many, primordial characteristics. It leads me to think that it may have originated very early on in the history of life.

Sam: Tanai is arguing that oxygenic photosynthesis—photosynthesis that we know and love where oxygen is produced—may have originated first, that it’s the most ancestral version. And then photosynthesis where oxygen is not produced followed.

After that around 2.3 billion years ago there’s a huge increase in the concentration of oxygen, which can be detected in the geological record, meaning in layers of rocks from way, way back in the day. Something was delaying the oxygenation of the atmosphere until then, maybe certain conditions on Earth that made some nutrients unavailable … we don’t really know. This is still an active field of research.

Deboki to Tanai: We've talked a lot about the past of algae. I'm curious what you think the future is gonna be like, you know, a lot of people get excited about eating algae or using it to make food or terraforming planets. Where do you think it'll go?

Tanai Cardona: A lot of the potential that we see with algae is with regards to what we can do with them, in the sense of coupling new processes to photosynthesis to power biotechnological processes that will be of importance to society using light as the sole input of energy. So that would be fossil fuel free technologies. Both algae and cyanobacteria, because they are relatively simple, and because we have tools to engineer their genomes, they have become attractive targets for biotechnology.

Sam: To learn more about how algae might be used in this way, we chatted with Nusqe Spanton who is the founder and CEO of Provectus Algae in Australia. We started by asking him about what biomanufacturing is, because I find it’s a term that just gets thrown around a lot and I didn’t really have a clear idea of what it meant.

Nusqe Spanton: Biomanufacturing from a really simplistic point of view is taking a microbe and making that microbe produce an ingredient or a material or a compound that's commercially valuable and doing that in a closed system. So think about this in like a big warehouse factory, in big stainless steel tanks or other vessels that these microbes can be produced in. Biomanufacturing allows you to really precisely control these microbes and the products in which they can produce. It allows us to transition from chemical synthetics of fossil fuel-based products to a bio-based product that is better for the environment. So it provides a huge opportunity for us to transition ourselves to a more sustainable manufacturing system.

Sam: Why on Earth would we want to move away from our current manufacturing system? Yeah I’m not being serious. Our current system is based on using fossil fuels like coal, oil, and natural gas that we all know shoot greenhouse gasses into the air. We think about fossil fuels in the context of heating and providing electricity to homes or keeping your car running. But fossil-fuel based ingredients like petroleum are also used in cosmetics and a huge range of other products.

Nusqe Spanton: Over the last hundred years, 200 years, of the industrial revolution, one of the key components that's allowed us to get to a point in which we are now where we have advanced materials, we have products on demand for ingredients in food products such as flavorings or fragrances, colorings, moisturizers, a lot of these chemicals aren't actually derived from natural based production systems.

So what we as human beings have developed over the last hundred years is chemical synthesis. And this is the ability to take fossil fuel based carbon chains and clip those carbon chains apart to basically make anything that we want. And what we're looking to do now with biomanufacturing is transition back to instead of taking those fossil fuels out of the earth to produce everything that we now know and love and, and essentially are addicted to in our daily lives, is converting that across to the living organism in algae and being able to harvest carbon dioxide out of the atmosphere instead of pumping it back into the atmosphere with fossil fuels and produce all of the products and ingredients that we know and love.

Nusqe Spanton: we're building something much bigger than a single product. What we're building here is an entirely new biomanufacturing platform.

We do have demonstration products that prove the platform and our capabilities across many different formats. Some of those that we're focused on include specialty ingredients for the alternative protein market, such as unique colorings that perform the same way as animal blood that aren't any heme based product. These are natural algae strains that have the ability to perform and cook and taste and, and look the same as a raw meat product would without having any genetic engineering.

These products you'll be seeing coming to market this year. We also have additional bioactive cosmetic ingredients for collagen induction and moisturizing and UV blocking.

Deboki: Nusqe told us that another product they’ve worked on to prove the platform works is an algae-produced alternative to palm oil, which is used in cooking and tons of different packaged products. Palm oil production is a massive cause of deforestation in the tropics, so getting algae to produce a comparable oil on a large scale would be incredible.

So instead of burning and breaking down fossil fuels to make products, algae use light and capture carbon dioxide. That seems like a pretty great swap. So why haven’t we been using algae instead of fossil fuels for decades at this point?

Nusqe Spanton: there's a reason why algae hasn't been used at any global scale before. It's extremely tricky to work with, because we've never really had the technology or the understanding of what it requires to grow. And that’s the fundamental basis. How light works in water is very different to how it works when coming into our atmosphere and shining on us. The understanding of light is a very complex thing. And here we've got an organism that essentially requires converting light energy into chemical energy.

And these organisms are moving around in this aquatic environment and they've needed to evolve mechanisms to harvest that light in different ways and repel the light in different ways.

So in our manufacturing systems, we've built hardware, a software platform with machine learning and artificial intelligence, but all of this technology has now allowed us to look deeper inside of algae and understand what it requires to grow and more importantly, what we need to give it to be able to produce the materials and the chemical compounds that we desire for commercial applications.

Sam: At the end of the day, the way we humans are doing things, and have been doing things since the beginning of the Industrial Revolution, needs to change immediately if we want to survive and if we want our planet to still look like our planet.

Nusqe Stanton: We can't continue down the pathway that we currently see. And if we think about the basics of existence on planet Earth, algae was the reason essentially for us to be here on planet Earth without algae pulling that carbon dioxide and the greenhouse gasses out of the atmosphere. We wouldn't be here on a habitable planet today. And so whether we like it or not, whether we're still here or not, algae will colonize this planet and it will convert it back to something that's livable if we decide to go down a pathway that we're seeing now.

Sam: Should we Tiny Show and Tell?

Deboki: Yeah. Let's do our Tiny Show and Tell.

Sam: Let's do it.

Deboki: We should really get a theme song for a Tiny Show and Tell.

Sam: Like a jingle?

Deboki: Yeah.

Sam: That'd be fun. Any listeners good at making jingles, let us know.

Today I'm talking about… kind of the moon, kind of earth. It feels relevant to this episode, but it feels maybe even more relevant to the episode that's coming out after this one. So, this is a little preview. It will be a space-themed episode.

Okay. Let's talk about the leading theory for the origin of the moon. The idea behind how we got the moon, and I think it's pretty well accepted, is that a Mars-sized planet, which has been dubbed Theia or Theia, T-H-E-I-A, struck early earth, which ejected this cloud of debris into space that later coalesced. It's how we got our moon.

And now, there's this new computer simulation that this group has done to suggest that the remains of Theia are actually deep inside our planet and might have triggered the onset of subduction, which is a feature of modern plate tectonics.

Of all the worlds that have been discovered, ours is the only one that seems to have plate tectonics. Earth's plates have been shifting around for billions of years, lifting up mountain ranges, creating volcanoes. Yeah, the plate tectonics are really, really important. So, apparently there are these two continent-sized blobs of material in earth's lower mantle. And they seem to have been involved in a bunch of the subduction that happened right after the moon formed. And now, using a computer simulation, researchers have come to this conclusion that these masses probably came from Theia. The take-home is that this collision event that happened not only gave us our moon, but maybe also led to these moving tectonic plates.

It's cool to think that, if that is the case, then there might be something about these tectonic plates themselves that would help in the search for other earth-like worlds, is one of the arguments where this could be cool. However, this is something that scientists just published about. This is the early days. So it's still quite controversial, as a lot of these big theories are.

Deboki: That is so wild. That is so cool.

Sam: Yeah.

Deboki: I understand that, for the scientists who are doing this work, maybe a lot of this becomes intuition, but it's just so weird to me that we can see these things and draw conclusions about everything from the moon to our tectonics. That's so cool.

Yeah. And I will also say, in chatting with Jochen, one of the things that he said that wasn't included in the episode was that the scientists who study things that happened so, so long ago, they have to be comfortable taking big swings, because there's so little information. Of course, you need to have research behind the claim that you are making. But you have to, if you are working in that space, you have to be ready to make big claims, take big swings.

Deboki: I know why this ties into our next episode, but I like that it also still ties into this episode.

Sam: Me, too.

Deboki: Well, for my tiny show and tell, I want to bring us back home. I want to talk about this battle that could be happening in your home, right now, and you probably wouldn't know about it. And this is the battle between Black Widow Spiders and Brown Widow Spiders.

Sam: I did not know there were Brown Widow Spiders. Please continue.

Deboki: Oh. Oh, yeah. There are. Most of us are probably pretty familiar with Black Widow Spiders. They live in homes. They've got that distinctive red mark. And they're venomous. They're a little bit scary in that regard.

If you get bitten, you should definitely get that taken care of, though apparently not that many people die from a Black Widow bite. The thing is, Black Widows, they don't actually like to bite people. They prefer to run away or to play dead, maybe throw some webbing, apparently. That's another technique they do. They're just shy spiders, in general.

Now, the Brown Widow Spiders, on the other hand, they're not as venomous as Black Widow Spiders, but they're also not as shy. Apparently they might have come to the US around 1935, probably from South Africa. And they're not just curious about their surroundings. They're aggressive about it.

So, there was this science tutor named Louis Caticio. He started to notice that, when he was looking at different homes, that if Black Widows lived in that home, but they ended up overlapping with the territory of Brown Widows, the Black Widows would just eventually not be there anymore. They would just vanish. And it didn't seem like this was an issue of two species competing for food. So, scientists were suspecting that there was actually some kind of aggression going on between these species, and they decided to see what would happen then if you put Brown and Black Widow spiders in the same enclosure along with some other related species.

And they found that the Brown Widow Spiders would target the Black Widows, and kill them, around 6.6 times more than they would target any other species.

Sam: Oh, my god.

Deboki: And, in general, Brown Widows were more aggressive. As they got older, they seemed to be a little less likely to go after the Black Widow Spiders.

And the thing is, also, the Black Widows were never provoking the fight. Again, they're shy. It's the Brown Widows who were starting this. The scientists think that what might be happening is that, because there were these other species, and the Brown Widows didn't seem to go after them, it just might be that those species put up more of a fight. The Black Widows, they don't really fight back that much. They just run away. So, maybe they were just easier targets in that regard.

The good news, hopefully maybe, for Black Widow spiders, and I never thought I would say the good news for Black Widow Spiders, the good news for them is that Brown Widow Spiders tend to stick to urban areas, but Black Widows, they can actually branch out and survive in the wilderness. Maybe if they get kicked out of our homes, they'll find a place somewhere else so that Brown Widow Spiders can't find them. But yeah, that is the tragic story of the Black Widow Spider.

Being someone who grew up on the east coast, I did live in San Diego for five years. But other than that, I have never lived in a range for really any spiders that are scary or potentially venomous.

Deboki: I know people really hate spiders, but I don't mind them. I'm definitely a person where if I see a spider, I just let it hang out where it is.

Sam: I don't like seeing a spider in my shower stall, but otherwise, I'm also usually okay with it.

Deboki: I didn't expect to come out of this sympathizing with the Black Widow Spiders, but, yeah.

Sam: You never know.

Thanks for tuning in to this week’s episode of Tiny Matters, a production of the American Chemical Society.

Deboki: This week’s script was written by Sam and was edited by me and by Michael David. It was fact-checked by Michelle Boucher. The Tiny Matters theme and episode sound design are by Michael Simonelli and the Charts & Leisure team. Our artwork was created by Derek Bressler.

This episode was edited by Russell Silber. Thanks so much to Jochen Brocks, Tanai Cardona, and Nusqe Spanton for joining us. If you have thoughts, questions, ideas about future Tiny Matters episodes, send us an email at You can find me on social at samjscience.

Oh and we’re selling Tiny Matters coffee mugs! I’ll put a link to those in the episode’s description.

See you next time.