Last week, the Mars rover Perseverance made it safely to the surface of Mars.

Over the two years or so, the car-sized rover will be driving around the red planet, looking for signs of ancient life. But, according to a new study in Frontiers in Microbiology, there’s a chance, albeit slim, of finding somewhat recently-dead microbes or even current life.

That’s because our missions to Mars could be carrying microscopic critters with them. And those microbes could survive for longer than you’d expect, even on the harsh surface of Mars! The surface of Mars is very different from the surface of Earth.

Its atmosphere is much drier than ours, and thinner. So the planet doesn’t have the thick barrier which helps protect us from much of the sun’s damaging, high-energy radiation. Plus, Earth has a layer of ozone adding to that radiation shielding — Mars doesn’t.

Oh, and did I mention it’s cold there? Like, it’s an average of -63 degrees Celsius! All of this could make it hard for anything from Earth to survive.

But microbes can be pretty tough. And if Earthly microbes can survive on Mars, then every mission we send could be a contamination risk — especially crewed missions where the environment inside the vessel would have to support life. this is not a simple thing to test, because it’s not easy to recreate that perfect mix of terribleness in the lab. So, in order to simulate a world without our thick atmosphere and ozone layer, the international team of researchers behind the recent paper went above it with a special microbe habitat they’ve dubbed the MARSBOx.

They put a strain of Aspergillus fungus and a couple strains of bacteria inside, and gave some of them UV shielding. Then, they filled it with a mix of gases similar to the atmosphere on Mars, and attached the whole thing to a scientific balloon that carried it high into the outer part of Earth’s atmosphere. After five hours, the balloon came back down, and the scientists were able to see what, if anything, survived.

And some of the microbes did, especially the Aspergillus spores — even without the UV shielding. So, any mission to Mars may need to consider microbial hitchhikers. After all, we wouldn’t want to accidentally contaminate Mars’ potential biosphere.

We also don’t want astronauts to get sick. Aspergillus is one of the fungi that causes “black mold”, and, on rare occasions, it can cause painful infections. And Aspergillus was previously found growing in the international space station, so it’s something that likely could live in a ship taking people to Mars.

On the flipside, some scientists are looking for ways to ensure microbes from Earth make it to and survive on Mars. That’s because we could harness those microbes to produce food or resources. And a separate study in Frontiers in Microbiology last week suggests that’s a real possibility.

Once we put humans on Mars, those people will need oxygen, water, and food. And Earth is a long ways off, so they’ll need them to be able to survive on their own. But we’re nowhere near figuring out how to grow entire gardens on the red planet.

Luckily, we don’t need potatoes to get the job done. We could grow microbes like cyanobacteria, which produce oxygen and can act as a protein source for us or other edible organisms. The problem is, cyanobacteria evolved here on Earth, and, like we said earlier, Mars is a very different place.

Even though it has some of the same gases, nutrients like phosphorus in its soil, and maybe even water — if locals could mine it from the planet’s ice — the air pressure is way too low. We’re talking only around one percent of the air pressure here on Earth! Now, we haven’t studied how bacteria grow in low atmospheric pressure all that much, but it seems like lower pressures can make it harder for microbes to take up the gases they need.

Also: it turns out that about one percent of Earth’s atmospheric pressure, plus a. Martian-plausible temperature of just above zero degrees C is water’s triple point. Meaning under those conditions it can exist as a liquid, gas, or solid. Imagine being a poor little cyanobacteria trying to grow in water that’s both freezing and vaporizing at the same time!

People might be able to get around this whole low-pressure issue by creating an enclosure that perfectly mimics Earth’s atmosphere — a kind of cyanobacteria pressure cooker, if you will. But a structure robust enough to pressurize the air that much would probably be too heavy to carry through space. So scientists have been trying to find some kind of middle ground, and they think they’ve hit on something that could work.

A research team from the University of Bremen has designed a proof-of-concept bioreactor they’re calling Atmos. It’s made up of nine one-liter vessels made of glass and steel, so it looks a bit like soda bottles in a very strange washing machine. But inside, cyanobacteria are bathed in an atmosphere that’s about one-tenth of Earth’s air pressure at sea level, but roughly ten times what they’d experience on Mars.

And that’s apparently enough for them. The scientists found that, using these conditions, colonies of cyanobacteria could grow just as big as those in Earth’s atmosphere — so, maybe, they could form the bottom of a Martian food chain. The best part, though, is that the light-weight, low-pressure enclosure could work with what’s available on Mars.

The nitrogen and other gases could be refined from the atmosphere with existing tech, and nutrients could come from the Martian soil. It won’t be Atmos specifically that goes to Mars one day, but this opens the door to further research and refinement. So all of this suggests that we really could, eventually, have a cyanobacteria farm on Mars, helping provide oxygen and nutrition with no support from Earth.

There’s more work to be done, of course, like optimizing everything so that the bacteria grow as fast as they can. And eventually, this kind of tech will need to be actually tested on Mars. Still, it’s a solid step towards the hope of a Martian colony.

Thanks for watching this episode of SciShow news! We’re here every Friday to cover some of the latest news from the world of science. So be sure to come back here next week for more!

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