Thanks to Lego City Space for supporting this episode of SciShow.  Lego wants to inspire the next generation of space explorers through building and play.

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With the way things are looking in space exploration these days, it's not impossible to believe that in the future, we'll send humans to live on Mars.  If we do, I'm sure it'll be amazing.  People will feel inspired and we'll learn so much about the solar system.  But those aren't the only things we would get out of this.  To live, sleep, eat, and breathe on Mars, these astronauts will need some of the very best tech we can dream up, but as a bonus, that tech could actually help us tackle challenges on Earth, too.

Here are three ways that living on Mars could also improve our lives here at home.  One thing future explorers will need is molecular oxygen, or O2.  After all, the Martian atmosphere is mostly carbon dioxide, which is very different from what we can breathe.  Astronauts will need some way to create a habitable atmosphere, and the cool thing is the tech they might use to do that could help us fight climate change here on Earth.

To breathe on Mars, most engineers agree that the best solution isn't to haul gigantic cannisters of oxygen from Earth, so instead, they're looking at ways to turn some of the CO2 in the Martin atmosphere into O2, and that's harder that it sounds.  CO2 is a pretty stable molecule and generally you have to put in energy of some kind to persuade it to give up its oxygen atoms, but we have found some ways to do it.  

One way is to use electricity to split CO2 into carbon monoxide and oxygen, and that method is scheduled to be tested as part of NASA's Mars 2020 mission, in an experiment known as MOXIE, but another method was published in 2019 in the journal Nature Communications, and it uses even more extreme chemistry.  In this study, the authors smashed CO2 molecules into gold foil.  CO2 molecules are normally shaped like a straight line with the oxygens at either end, but this method bent them out of shape.  That brought the two oxygens closer together and made it easier for them to react to form O2 and an atom of carbon.

The yield was pretty poor with only around 1% of the CO2 molecules producing proper O2, but hey, this strategy's in its early days.  This kind of science would be game-changing for future Martians, but here on Earth, CO2 is more of a problem than a resource.  We're adding more of it to our atmosphere every day, and it's warming the planet, something we can't afford to ignore, so removing excess CO2 from our atmosphere is a long-term priority for scientists and reactions like the ones they might use on Mars could help with that.  After all, things like MOXIE or that gold foil reaction don't just make O2, they also destroy carbon dioxide, and the authors of the 2019 study have suggested their methods could be applied here on Earth to get some of that extra CO2 out of our atmosphere.

Now the next thing astronauts will need to live on Mars is some good clean soil, both for potentially growing food and just for general day-to-day safety.  The biggest problem here is that scientists believe Martian soil is full of a chemical called perchlorate, which is toxic to humans.  It interferes with the thyroid gland which normally regulates our metabolisms, so in the short term, it would be necessary to protect astronauts from direct exposure to Martian dust, since they could track it into their habitat whenever they ventured out to explore, and over longer time scales, any crops grown in that dirt could pick up perchlorate, meaning they'd be at risk of getting people sick, but perchlorate isn't just a problem on Mars.  Here at home, it can also contaminate our drinking water, so figuring out how to clean soil on the red planet wouldn't just be good for astronauts.  It would be important for everyone.

Right now, there are some ways to chemically degrade perchlorate in ground water, but it can be hard to get perchlorate to react with cleaning agents, so the solutions proposed for Mars could be really useful.  So far, some research groups have proposed that we could clean Martian soil by growing certain bacteria in it.  These microbes produce enzymes that can break down perchlorate into less toxic chlorite, and as a byproduct, the process would also give off molecular oxygen, which is a nice bonus.  In fact, in a 2013 article, scientists propose we could even incorporate these enzymes into a portable emergency oxygen system that astronauts could use on the fly.  They'd just have to scoop up some dirt, mix it with water and some of the enzymes and let their suit feed them fresh O2.  So not only would we get cleaner soil and a simpler way to treat groundwater on Earth, but we'd also get an emergency oxygen mechanism.

Finally, if we're gonna stay on Mars for any significant length of time, we'll need to build habitats, because at some point we'll probably run out of room in our spacecraft.  On Mars, traditional building materials like concrete and steel bars probably won't be an option, since they're not exactly abundant there and they're way too heavy and expensive to launch on rockets, so engineers are turning to other solutions, and on Earth, those ideas could help us build more sustainable buildings and decrease the impact we have on our beautiful green planet.

Recently, NASA challenged engineers to come up with a way to 3D print whole buildings on Mars, and in May 2019, they awarded half a million dollars to the winner of that challenge, a company called AI Space Factory.  Their design uses a telescoping 3D printer arm mounted on a rover.  It can build entire structures autonomously and it uses materials that can be found or made on the red planet.  Specifically, the design calls for basalt derived from Martian rocks mixed with PLA, a kind of plastic that can be made from plants, plants that would be grown on Mars.

In NASA's competition, a 1/3 scale model of the habitat withstood a battery of tests for things like durability and water leakage, but the company behind this technology also intends to deploy it closer to home.  See, basalt and PLA are readily available on Earth.  Basalt is just a kind of rock and PLA is a form of plastic that's actually compostable, so according to AI Space Factory, this technology can produce totally recyclable homes and they're already crowdfunding efforts to build some.

It might not seem like we need something like this here on Earth, but the reality is the concrete and steel industries produce a lot of waste, and those materials aren't exactly reuseable.  It would be a lot nicer for our planet if we could make our homes and buildings out of something that could ultimately be recycled.  At the end of the day, it will take clever strategies like these and many more to help astronauts live and work on Mars, but from fighting climate change to building more sustainable homes, they have a lot to offer the rest of us here at home as well, and it's never too early for the next generation of engineers to start learning to innovate and build tech just like this, and Lego City Space wants to help with that.

These sets were inspired by real tech challenges like the ones we talked about today.  50 years ago, we went to the Moon, and the explosion of innovation that accompanied that giant leap was unparalleled.  What will we make when we go to Mars?  There's no way to know yet, all the more reason to inspire our young future engineers to get playing and creating.  We used kits like the Space Research and Development People Pack, Rover Testing Drive, and a Lunar Space Station to help make this video.  Click the link in the description to start building your next interplanatary adventure with Lego City Space.  Let's go!

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