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The water on Mars probably doesn't have much oxygen, but new models show that life doesn't need as much O2 as we thought. And NASA is sending a claw machine to the red planet!

Thanks to Vlada Stamenković for his thoughtful answers to our questions!

Host: Hank Green

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[ ♪ Intro ].

We’ve added a lot to the classic picture of Mars in the last few years, especially where water is concerned. Between the pretty strong evidence of salty liquid water scattered across the surface, not to mention the giant lake that might be hidden deep under the south pole, it seems like there’s a surprising amount of liquid water over there.

And in a paper published this week in Nature Geoscience, researchers found that all this water we’ve been finding might actually contain enough oxygen for certain forms of life to survive there. Not just simple unicellular microbes, either. In some places, there might even be enough oxygen for more complex life to survive.

So water is super important to the search for life on other worlds, because as far as we know, life can’t survive without it. But of course, there’s a big difference between figuring out whether life could survive on Mars and actually finding life there. And even with the evidence of liquid water, we’re still working on that first one.

The main problem is that the water on Mars is full of a type of salt called perchlorates, which happen to be pretty toxic to life as we know it. But we know that life can adapt to all kinds of extreme conditions. And when we talked to Vlada Stamenković, one of the authors on the new paper, he noted in a place like Mars where there are perchlorates everywhere, adapting to them might just be normal.

Still, when scientists talk about life surviving on Mars, they’re pretty much always referring to anaerobic life, simple, unicellular life that doesn’t need oxygen to survive. More complex, aerobic life does require oxygen, and since there’s not much of it on Mars, most researchers assumed aerobic life wouldn’t be able to survive there. At least, until now.

Other recent studies have found that aerobic life doesn’t need quite as much dissolved oxygen to survive in water as we used to think, only 0.032 parts per billion for single-celled microbes, which is … not a lot. For comparison, oceans on Earth have about 200 thousand times that. So the authors of this week’s paper wanted to see if the oxygen content of Martian brines would be enough to support aerobic life.

When they put together a model of how oxygen would dissolve in the brine based on the conditions on Mars, they found that there were large areas of the planet where the brine would have enough oxygen to support aerobic life. And on about 7% of the surface, the model showed that there might even be enough oxygen to support more complex, multicellular life, like sponges, which need about 2000 times as much as single-celled aerobic life. The researchers focused on the small brine deposits close to the Martian surface, not the giant lake we think might exist about a kilometer and a half below the planet’s south pole.

But they said that according to their results, the lake would probably have lots of dissolved oxygen, too, as long as it has a reliable source of the stuff, like from the atmosphere or from radiation breaking down water molecules. Obviously, none of this means there is aerobic life on Mars, or that life exists there at all. But Stamenković also pointed out that oxygen was a huge factor in the evolution of complex life on Earth.

So finding enough oxygen to support aerobic life right next door opens up a lot of new possibilities in the search for life on Mars, and maybe on other worlds, too. Meanwhile, NASA’s InSight lander is on its way to Mars, set to touch down in late November. It’s not designed to study places where we think life might be able to survive, since it’s so hard to make sure we don’t contaminate those places with microbial hitchhikers from Earth.

Instead, InSight is going to study the planet’s interior to learn more about how rocky planets formed in the Solar System. And last week, NASA released a video with more details about how exactly that will work. It involves … the claw...

Did I do a good job of that? Seriously, though. Since InSight’s mission is to study the Martian interior, which we’ve never properly done before, its scientific instruments need to be in direct contact with the surface.

So the lander’s robotic arm has a claw attached to the end that it will use to pick up those instruments and place them on the ground. In other words, the highly-sophisticated robotic lander we’re sending to another planet is basically a glorified claw machine. Unlike the machines you dump money into at the arcade, though, the lander’s mechanism is designed to actually pick things up.

The mission team considered a few other options, but there were problems with all of them. A magnet, for example, might not work if too much dust got in the way. It’s actually a pretty cool bit of engineering, the mechanism opens up by heating up wax, which then expands, putting pressure on a rod that opens the claw.

Then you just lower the open claw onto whatever instrument you want to move. They all have hooks for the claw to grab onto. When the wax cools, a spring pushes the rod back into place, closing the claw.

And once it’s in place, it will stay closed even with the instrument pulling down on it, unlike the claws in arcade machines, which are designed to open when something pulls down on them. So if InSight happens to find any little three-eyed green aliens waiting for it on Mars, they won’t stand a chance. Thanks for watching this episode of SciShow Space News!

And thanks especially to our Patreon President of Space SR Foxley and our community on Patreon for supporting what we do. You might have seen our livestream extravaganza earlier this week, where we tested some fun experiments, did a live quiz show, and tried very hard to blow up a pumpkin. But most importantly, we got to connect with people who share our passion for spreading scientific knowledge to anyone who wants to learn.

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