Thanks to our friends at Minute Earth  for supporting this episode of SciShow.

You can click the link in the  description to check out their new book, it is absolutely wonderful; MinuteEarth  Explains: How Did Whales Get So Big? And Other Curious Questions about Animals,  Nature, Geology, and Planet Earth. [♪ INTRO] The Apollo missions of the sixties and  seventies inspired millions of people to become scientists and engineers, but  the astronauts who landed on the Moon also came home with something far more tangible: 382 kilograms of Moon soil,  also known as regolith.

Some of those samples have  been lost or stolen since then, but most were studied with the  best technology of the time. And a few untouched samples  were locked away so that the scientists of the future, with new  methods and new instruments, could learn from those pieces of the Moon what  scientists of the seventies could not. And, well, welcome to the future.

It  is time to look at some Moon rocks. Most of the samples brought  home by the Apollo astronauts were studied decades ago,  answering countless questions about the Moon’s age, origins, and history. Questions like why do we have  a Moon in the first place?

Scientists found that the oldest  Moon rocks were a little younger than the oldest stuff in the Solar  System, and that they looked a lot like what’s in the Earth’s mantle. These observations helped lead  to the Giant Impact Hypothesis: The idea that a young, moonless Earth collided with something about the size of Mars. That crash launched a whole bunch  of the crust and mantle into space, which clumped together into  what we know today as the Moon.

Other scientists discovered lots of  natural glass in the Moon rocks that are billions of years old, something  that cannot happen on Earth because the water in our rocks tends to break  down glass in those rocks over time. This made scientists think that the  Moon rocks had almost no water in them. And when they checked,  those rocks looked bone dry.

So everything seemed to fit together. Now, water is a good example of why we  held some samples back from testing. Before Apollo, many scientists  believed the Moon would be pretty wet.

But by 1984, a NASA report confidently stated: “We now know that hypothesis  to be completely false.” Except, within the next 15 years, radar  signals from two separate satellites revealed evidence of at least some ice trapped in the rocks near the Moon’s south pole. Other evidence from satellites  and telescopes has only gotten stronger over the past almost thirty years. Today, everyone still agrees:  The Moon is way dryer than Earth.

But the picture is definitely  muddier than it used to be. Which naturally makes scientists wonder  whether the original samples were just super-dry or the instruments  in the seventies weren’t sensitive enough to see the water in them. The good news is that these sealed samples give us new ways of answering those kinds of questions.

In 2019, scientists from the Apollo  Next Generation Sample Analysis Program, or ANGSA, got ready to study untouched Moon rocks for the first time in over forty years. So the ANGSA group looked at a tube of material collected on Apollo 17 by astronaut Gene Cernan. He stuck the tube into the ground,  so the Moon’s surface is at the top, followed by about twenty centimeters  of whatever was underneath.

That tube was sealed and brought back to Earth, X-rayed, and then stored for decades, until 2019. The hope is that scientists can use  this sample to see how the surface has changed over time, just  like geologists on Earth study rock layers to learn  about an area’s history. Now, back when the tube was first X-rayed,  we got this picture of what’s inside.

Then, in 2019, scientists imaged  the sealed tube again with X-ray computed tomography,  where a lot of X-ray images from different directions were  stitched together into this 3D model. So that’s the kind of improvement  we’re talking about here. Then, the tube was opened, and the sample was split up so that it could be studied  in a bunch of different ways.

That was late 2019. Just like the rest of us, ANGSA had big  plans for 2020, including opening another sample that might have some of the Moon’s  super-thin atmosphere trapped inside. But like the rest of us, those plans were…delayed.

So far, we know that the material in  this tube starts looking a lot different once you get past the surface, going from  less soil to more rock and mineral-like. This means that the Moon’s  surface here was layered, possibly because of some sort of landslide  after an asteroid hit the surface. They'll also be looking for evidence  of amino acids in the samples, to try to figure out if previous  results of amino acids in regolith are original to the moon, or an  example of cross-contamination.

Opening that second sample was also delayed, but other groups are hard at work  understanding what’s going on in there, too. It’s the same core as the  other one, but from lower down, so it should let scientists investigate  even farther into the Moon’s past. And if there really is some atmosphere  trapped in there, scientists may learn a lot about how the Moon’s surface  interacts with the solar wind, micrometeoroids, and the  other ravages of outer space.

But, you may be asking yourself, why open it now? Yes, our technology is better  than it was in the seventies, but it’ll probably be even better in the 2040s. Well, it’s partly because  between China’s robotic missions and NASA’s Artemis program, there’s  a lot of interest in the Moon lately.

And knowing whether there’s water on the Moon would help us know how to sustain  a colony up there someday. Because water isn’t just water. It’s also hydrogen and oxygen:  Breathable air and rocket fuel.

So now is as good a time as  any to open those samples up and learn whether water, and  any other exciting discoveries, that can tell us about the Moon’s  past, or our future, are up there. Now is also a great time to buy a  book for the young one in your family and our friends at Minute  Earth can help with just that! This book answers children’s  most curious questions like “Where Earth’s water came from” and  “Why leaves change color in the fall.” And all of it is accompanied  with gorgeous illustrations.

You don’t have to inspire curiosity in a child. They are naturally curious. All you have to do is respond to it  with great resources like this one.

And often times you can find  yourself learning along side them; not just about the world, but also about the kid. If you like what you see and you’d  like to snatch a copy of this book, you can head to dftba.com/collections/minuteearth or you can just click on  the link in the description. [♪ OUTRO]