Why did we go back to the moon?

For the first time in over 50 years, humans have gone to the moon and back. And this time, NASA says we're going to stay. NASA's planning for more missions, a permanent moon base, and even a mission to Mars. But there's a pretty big question hanging over all these dreams: Can humans survive in space long enough to make them happen?(A version of this episode originally aired in 2022, with the launch of Artemis I.) Guests: Anne McClain, NASA Astronaut; Scott Kelly, former NASA Astronaut; Rebecca Boyle, science writer, Jonathan Jiang, NASA astrophysicist For show transcripts, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unxtranscripts⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ For more, go to ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/unexplainable⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ And please email us! ⁠⁠⁠[email protected]⁠⁠⁠ We read every email. Support Unexplainable (and get ad-free episodes) by becoming a Vox Member today: ⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠vox.com/members⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠⁠ Thank you! Learn more about your ad choices. Visit podcastchoices.com/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:01Noam Hassenfeld?

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• 1:24Speaker 02

  This is Victor. We are going for our families.

• 1:28Speaker 03

  This is Christina. We are going for our teammates.

• 1:32Speaker 02

  This is Jeremy. We are going for all humanity.

• 1:36Speaker 03

  Godspeed, Artemis II. Let's go.

• 1:41Speaker 04

  10, 9, 8, 7. RS 25, engines lit. 4, 3, 2, 1. Booster ignition. And liftoff! The crew of Artemis II now bound for the moon. Humanity's next great voyage begins.

• 2:02Noam Hassenfeld?

  Four astronauts on Artemis II just traveled further than anyone in history.

• 2:08Speaker 02

  We challenge this generation and the next to make sure this record is not long lived.

• 2:15Noam Hassenfeld?

  It's the first time in over 50 years. Humans have been so close to the moon.

• 2:19Speaker 02

  You know, I'm not one for hyperbole, but it's just absolutely unbelievable. This is incredible.

• 2:27Speaker 05

  Copy moon joy.

• 2:28Noam Hassenfeld?

  The vibes are so good that Mission Control just spontaneously went, "Copy moon joy." And now it's become this kind of catchphrase.

• 2:37Speaker 05

  Everyone is reporting full moon joy.

• 2:40Noam Hassenfeld?

  Scientists are even talking about putting it on T-shirts.

• 2:42Speaker 02

  Houston, if you could give me about 20 new superlatives in the mission summary for tomorrow, it'll help my vocabulary out a bit. Thank you.

• 2:50Noam Hassenfeld?

  The astronauts on Artemis 2 didn't land on the moon. They just orbited it. But the mission was a crucial step towards getting back to the surface again, which NASA is planning to do in 2028. And they've got a different goal this time.

• 3:02Speaker 04

  This time, we're going back to stay.

• 3:07Noam Hassenfeld?

  We ran a version of this episode a few years ago when Artemis 1 launched, and we wanted to share it again this week because it's easy to get lost in all these incredible photos of the moon and Earth and miss out on the larger context of just how big a step forward this all is. The entire Artemis program is just setting the stage. Eventually, NASA is hoping to build a permanent base on the moon.

• 3:31Speaker 04

  And our goal is to apply what we've learned, living and operating on the moon, and continue out into the solar system for humans to walk on Mars by 2040.

• 3:44Noam Hassenfeld?

  A moon base and a mission to Mars could be the first steps toward becoming a multi-planetary species where Earth isn't our only home. Eventually, we can imagine a solar system full of human life.

• 3:57Speaker 06

  Human settlements in space in which tens of thousands of people will live and work.

• 4:03Noam Hassenfeld?

  But there's a pretty basic thing standing in the way.

• 4:07Speaker 02

  Okay, you know, we've had a problem here.

• 4:09Speaker 01

  Space is terrible. It wants to kill us.

• 4:12Noam Hassenfeld?

  Science writer Rebecca Boyle.

• 4:14Speaker 01

  You know, we've evolved to live on this planet and this planet only.

• 4:18Speaker 02

  I tell you, if he gets pulled up in there.

• 4:21Noam Hassenfeld?

  Whether it's the weightlessness, the radiation, or even the isolation, space is trouble for lots of different kinds of life.

• 4:28Speaker 01

  It's hard to raise fish or rats or mice or any other kind of species that we've taken up there.

• 4:35Noam Hassenfeld?

  Three mice died in space, as did eight gerbils.

• 4:38Speaker 01

  It's hard to even grow plants in microgravity.

• 4:41Noam Hassenfeld?

  Which makes NASA's grand vision of a permanent presence far from Earth a pretty risky proposition.

• 4:47Speaker 01

  Space is really nasty and it's very hard to be there for any period of time, even with a spacesuit and a space station surrounding you.

• 4:56Noam Hassenfeld?

  Okay, everybody, look, we got a number of long-range problems right now. And we barely understand the dangers of space, especially when it comes to living far away from Earth for a long time. Like, over 600 people have been to space, but only 28 of them, just 4%, have been more than 1,000 miles from Earth.

• 5:14Speaker 02

  We'd like to confirm that the world is round.

• 5:18Noam Hassenfeld?

  And that tiny handful barely spent any time out there.

• 5:22Speaker 01

  I mean, the longest Apollo missions were just a few days. Odyssey, Houston. Welcome home, over.

• 5:30Noam Hassenfeld?

  That's where the Artemis program comes in. It's often presented as just the next logical step in space, but it's also an experiment to see just how possible NASA's grand vision really is.

• 5:42Speaker 01

  The real goal of all these programs is to learn how to live and work really far from Earth. How bad is it? How much can we handle?

• 5:53Noam Hassenfeld?

  I'm Noam Hassenfeld, and this week on Unexplainable, what does space do to the human body? And if we're planning to have a permanent presence on the moon or even Mars, are we sure we can actually live there?

• 6:20Noam Hassenfeld?

  Almost everything we know about the long-term effects of humans in space has come from low Earth orbit, this area of space just a couple hundred miles from Earth's surface. That's where astronauts like Anne McLean have spent significant time on the International Space Station.

• 6:35Speaker 03

  You wait your whole life to launch to space, and then suddenly it happens.

• 6:40Noam Hassenfeld?

  Anne first launched to the ISS in 2018.

• 6:43Speaker 03

  I just remember feeling the thrust and just kind of this realization that you're leaving the planet, and it's really hard to describe. But it's like you're processing something that your brain doesn't have the capacity to process because there just hasn't been anything like it before.

• 6:57Noam Hassenfeld?

  As she left the pull of gravity, she turned and she gazed out this little round window.

• 7:03Speaker 03

  It was all pitch black. And then I saw what looked like a little piece of like flame off of a Bunsen burner, you know, like a blue flame. And I thought to myself, well, that's, I wonder what that flame on our spacecraft is. And I realized that as it got larger, it was actually the sun coming up over the curvature of the earth. And I was watching my first sunrise.

• 7:26Noam Hassenfeld?

  In total, Anne spent over 300 days on the ISS, surrounded by the cold, dark vacuum of space.

• 7:34Speaker 03

  The walls of the space station are very thin, which is pretty surprising. You know, when you first get up there, you're like, oh, gosh, I don't want to accidentally punch a hole through the wall. It's not really going to happen, but these are the thoughts that cross your mind when you first get there.

• 7:46Noam Hassenfeld?

  And it didn't take long to notice the types of dangers those walls couldn't keep out. For one thing, there's the ionizing radiation, these tiny, fast-moving particles ejected from the sun or from distant supernova explosions.

• 8:00Speaker 03

  Just think about like if little atoms became bullets.

• 8:03Noam Hassenfeld?

  Many of these subatomic particles shoot right through the walls of the space station.

• 8:07Speaker 03

  When we shut our eyes at night up on space station, you can see what actually looks like a shooting star go by your eyes if you get hit by a piece of radiation.

• 8:15Noam Hassenfeld?

  It's not totally clear how this happens, but one theory is that these particles could be hitting astronauts' retinas and making their rods and cones fire, which would lead them to see a flash of light that isn't really there.

• 8:27Speaker 03

  And the first time you see it, you're like, wow. Because we hear about radiation on the ground, and then we go, oh, man, this like really fast atom moving through my head probably is not great for my body.

• 8:41Noam Hassenfeld?

  On top of the radiation, there's the issue of gravity.

• 8:44Speaker 03

  Gravity is an incredibly strong force. Well, when it leaves your body, your fluids shift up.

• 8:50Noam Hassenfeld?

  Your body is designed to constantly pump blood up from your feet, which makes sense as long as gravity is pushing down.

• 8:58Speaker 03

  It's like when you pick up the empty can of Coke that you think is full, and you kind of go, whoa, and you pick it up real fast.

• 9:03Noam Hassenfeld?

  And microgravity changes the pressure around astronauts' eyeballs.

• 9:06Speaker 03

  Some people experience a change in eyesight because you think about, maybe there's a little more pressure on the back of your eyeball. So instead of being shaped like almonds, they get to be a little more round.

• 9:15Noam Hassenfeld?

  Bone density is a problem, too.

• 9:17Speaker 03

  That's why now when you see astronauts on the space station, you see us lifting weights.

• 9:21Noam Hassenfeld?

  And because her spine wasn't constantly being compressed by gravity, the space between Anne's vertebrae actually expanded.

• 9:29Speaker 03

  I grew just under two inches in space.

• 9:31Noam Hassenfeld?

  Which was OK, except for her pants.

• 9:34Speaker 03

  I got up there and I put on the pair of pants and I thought, why did I choose these ones? They only go down to my ankles.

• 9:41Noam Hassenfeld?

  Until she came back to Earth.

• 9:42Speaker 03

  I shrunk right back down in a couple of painful days.

• 9:46Noam Hassenfeld?

  And finally, there's just the fact of being in space, confined to this tiny box for a long time.

• 9:52Speaker 03

  We do talk a little bit about space fog that just kind of makes you less likely to think quickly through things.

• 9:59Noam Hassenfeld?

  NASA itself acknowledges that the psychological impact from isolation is one of the most dangerous unknowns of long-term space missions.

• 10:07Speaker 03

  I mean, there was definitely days where I just, I felt like I never woke up, like I felt like I was half asleep all day long.

• 10:12Noam Hassenfeld?

  And for lots of astronauts, these changes, like cognitive troubles, bone problems, vision issues, they can last even after they get back to Earth.

• 10:24Noam Hassenfeld?

  But this is all just what space does to people in low Earth orbit. Things get significantly more difficult as astronauts get further from Earth. Take radiation, for example. Because the ISS is so close to Earth, it's actually shielded from most cosmic radiation by Earth's magnetic field. So even though there's enough radiation on the ISS to see these flashes, it gets way worse further out.

• 10:48Speaker 02

  I've got a series of random lines that are moving like a flashing horizon with thunderstorms on the horizon.

• 11:00Noam Hassenfeld?

  Have reported tons of these flashes.

• 11:03Speaker 02

  Oh, man, there's a good one. The left eye right in the middle. It starts out as a semicircle and then folds into a point like on a pencil and then it disappears.

• 11:13Noam Hassenfeld?

  Only 28 people have spent even a brief time exposed to this kind of radiation. And just from this limited sample, there's reason to worry. According to a 2016 study, these astronauts were four to five times more likely to die from heart disease than astronauts who stayed closer to Earth, just from being outside Earth's magnetic field for less than two weeks. And once NASA goes and builds a permanent moon base, astronauts are going to be spending potentially several months at a time there, which science writer Rebecca Boyle says is going to let them do two main things. One, they'll learn how to survive in an extreme environment, which will help NASA get ready for a mission to Mars.

• 11:51Speaker 03

  And eventually, people would just live there permanently, rotating in and out like the way we do on Antarctica or on the space station.

• 11:59Noam Hassenfeld?

  And two, they'll be near valuable resources on the moon, including water ice in its south pole.

• 12:04Speaker 03

  In theory, you could get that water and it could be used for rocket fuel.

• 12:09Noam Hassenfeld?

  If NASA can extract oxygen from this water ice, the moon can basically be a gas station for future missions to Mars. But despite all this potential, the moon isn't exactly a welcoming place. For starters, even though the pull of gravity is stronger on the moon than it is on the ISS, it's still six times weaker than it is on Earth.

• 12:30Speaker 03

  And turns out that's just at the threshold where it really starts to mess up your perception. People get kind of dizzy. There's actually a lot of videos of astronauts falling down on the moon.

• 12:41Speaker 02

  I fell down.

• 12:42Speaker 03

  Just like falling on their face.

• 12:45Speaker 02

  I just got my first initiation to getting very dirty. You sure did.

• 12:51Speaker 03

  They're just totally disoriented, like your vestibular system just can't kind of figure out where you are in space.

• 12:58Speaker 02

  Yeah, I look like an elephant stumbling around here.

• 13:01Noam Hassenfeld?

  On top of the weaker pull of gravity, astronauts who live on the moon will also have to deal with lunar night.

• 13:07Speaker 03

  That's another thing that makes the moon really unpleasant.

• 13:09Noam Hassenfeld?

  Any spot on the moon has two weeks per month where it faces away from the sun, which leads to some ridiculously cold temperatures.

• 13:17Speaker 03

  There's no atmosphere, there's no pressure, there's no, you know, warm sun or clouds overhead.

• 13:23Speaker 01

  It's really difficult for basic technology to survive that, let alone humans.

• 13:28Noam Hassenfeld?

  And then there's a danger that maybe even scarier than radiation, weak gravity, or the freezing cold, moon dust.

• 13:36Speaker 01

  So because there's no atmosphere to speak of, any dust that's moving around because of a spacecraft arriving or leaving is going to fly around like a scouring pad.

• 13:46Noam Hassenfeld?

  Apollo astronauts dealt with moon dust constantly.

• 13:49Speaker 02

  Man, I got so much dust over my visor already. I gotta wipe it off.

• 13:52Speaker 01

  There's kind of a constant stream of micrometeoroids hitting the moon, and that kicks up a bunch of dust.

• 13:59Speaker 02

  I tell you, it sure is easy to get dusty, but that's nothing to do with anybody.

• 14:03Speaker 01

  Some of it goes fast enough that it goes into orbit, essentially. And there's no air to absorb any of those particles or slow them down.

• 14:10Speaker 02

  Boy, you're gonna have to give me the dust of the year award after this.

• 14:14Noam Hassenfeld?

  I listened back to the tapes from Apollo 17, the last mission to the moon. And honestly, barely a few minutes went by without the two astronauts worrying about the dust.

• 14:23Speaker 02

  Man, I had it dusty.

• 14:26Noam Hassenfeld?

  But the moon doesn't have wind or waves like Earth does to make that dust softer.

• 14:32Speaker 01

  Every piece of moon dust is jagged and sharp. So it's just flying like bullets all over the place.

• 14:39Noam Hassenfeld?

  The dust would stick to astronauts' suits.

• 14:41Speaker 02

  Glad dust. Once you get it on there, you might as well forget it.

• 14:44Noam Hassenfeld?

  And then when they went inside the landing capsule, it just went everywhere.

• 14:49Speaker 01

  So there's no avoiding breathing it in.

• 14:51Speaker 02

  Glad dust. Get in there, buddy.

• 14:53Speaker 01

  And they all complained bitterly about it. And it hurt their throats, and it gave them a feeling like a head cold, like you were congested because there's so much crap you're breathing in.

• 15:02Speaker 02

  I have never seen so much dust in my whole life. Ever.

• 15:06Noam Hassenfeld?

  One of the astronauts actually got sick from all of it.

• 15:09Speaker 02

  It's come on pretty fast since I came back. I didn't know I had lunar dust, hey, Beaver?

• 15:15Noam Hassenfeld?

  In a post-flight debriefing, astronaut Jean Cernan said, quote, "I think dust is probably one of our greatest inhibitors." To a nominal operation on the moon. I think we can overcome other physiological or physical or mechanical problems, except dust.

• 15:31Speaker 02

  Man, I hate the dust.

• 15:33Noam Hassenfeld?

  That was his biggest worry after spending just a few days on the moon dealing with moon dust. All of these issues can pose acute problems, but long-term exposure is a whole different ballgame. Take moon dust, for example. We know what made astronauts sick on the moon, but studies have shown that longer exposure could lead to a higher risk of serious diseases like cancer down the line. So when you add that to the higher chance of dying from heart disease, from cosmic radiation, it might just be that spending a long time in deep space can't be perfectly safe. There's a real chance it can shorten your life. But even if living in space is always going to be dangerous, NASA isn't going to wait

• 16:16Noam Hassenfeld?

  till the long-term risks are zero, which they're fully open about with astronauts like Anne.

• 16:21Speaker 03

  I understand cognitively the dangers, but I can't say no. It's this passion that I just, I want to explore.

• 16:28Noam Hassenfeld?

  Rebecca says certain technologies could make long-term survival less risky, like NASA is researching drugs that could mitigate the effects of weak gravity, there are ideas to make space suits out of a type of plastic that would absorb more cosmic radiation. And when it comes to moon dust, NASA's experimenting with a kind of slick coating on space suits to keep it off. But there's one interesting solution that could potentially solve a bunch of these problems at once. There are actually some caves on the moon that are caused by lava flows that collapsed. And so in theory, like you could go under these domed kind of cave areas and burrow underneath the lunar soil. A lunar base inside a cave would be able to stay warmer during lunar night, and

• 17:13Noam Hassenfeld?

  it would be shielded from the constant stream of moon dust. You're also shielded from cosmic rays and solar rays if you're in a cave, like you're protected from being bombarded by any kind of micrometeoroids or radiation. And this isn't as far-fetched as it sounds. A couple of years ago, NASA found a series of deep pits or moon caves that hover at a constant temperature of 63 degrees Fahrenheit, which means there's a real possibility that the first permanent settlers on the moon could be cavemen, you know, go back to what worked for humans the first time around. Yeah, that's true.

• 17:46Speaker 01

  Go back to the caves and make their own art. And people in the future can talk about what they meant when they drew their rovers instead of bulls.

• 17:56Noam Hassenfeld?

  It's a fantastic thing to imagine. A moon base in a lunar cave, a mining operation at work in the background extracting material to power deep space rockets, an orbiting lunar space station serving as a staging point for these missions, and a rocket heading out toward Mars, slowly transforming into one of many tiny lights as it gets further and further away.

• 18:20Noam Hassenfeld?

  But at the end of the day, it's also worth asking, why? Given that we still only know just a tiny sliver of the risks of being far from Earth for a long period of time, is all of this worth it? Why do we want humans to be living in space to begin with?

• 18:37Speaker 01

  I mean, that's kind of the million dollar question for a lot of these programs is what's the point?

• 18:42Noam Hassenfeld?

  The million dollar answer after the break.

• 18:53Speaker 03

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• 22:14Speaker 02

  With the Artemis program, NASA's entered into a new era of space exploration. Artemis 2 just

• 22:20Noam Hassenfeld?

  Took humans around the moon and back for the first time in 50 years. And over the next three missions, NASA is going to test a lunar lander. They're going to put humans back on the surface of the moon. And they're going to start building a moon base. It's all going to teach us about living in space long term, far away from Earth. And ultimately, it's going to help us get ready for a mission to Mars. But it makes you wonder, if this is really about space exploration, why send humans into deep space at all? Why not just keep sending rovers? To start, there are some clear geopolitical reasons. China is planning to land people on the moon by 2030, and they're hoping to build a permanent moon base by 2035. So it might just be as simple as being first.

• 23:06Noam Hassenfeld?

  But to NASA astrophysicist Jonathan Jiang, living off-world feels a lot more urgent, something that isn't a choice as much as a necessity. I think any life like to spread, you know, and for the long-term survival, you need to move. If you stay one place, you're not going to survive long. For all we know, Earth could be the only planet in the universe with life. Suppose we are alone and we are precious. If we are destroyed, it means the life in the universe was gone. And it's not like this kind of destruction is so hard to imagine. There's a long list of apocalyptic events that could destroy us. Asteroids, pandemics, climate change, global nuclear war. People say, ah, nah, it's not going to happen.

• 23:51Noam Hassenfeld?

  But you check the Doomsday's Clock website, the chances have a global nuclear war right now. It's not zero. And when you start looking at longer and longer timeframes, this kind of destruction starts becoming more plausible. Suppose you buy a lottery ticket. The chances to win the lottery ticket is very low, but you buy a lottery ticket every day for millions of years, you're going to win. And zooming out even further, Jonathan says that it'll eventually be necessary to move way further out than just Mars, because the sun isn't going to be around forever. If we want to have a future for the humanities, even if our sun is dead, we got to become multi-planetary species.

• 24:33Noam Hassenfeld?

  To even think about the dangers of that far, far future, we need to survive long enough to make it there. For Jonathan, the best way to ensure the existence of humanity is to start learning how to live far from Earth right now, no matter how difficult it might be. But not everyone wants to think billions of years into the future.

• 24:55Speaker 03

  I don't want to give up that easily on Earth. You know, this is the planet that we evolved on.

• 25:00Noam Hassenfeld?

  Science writer Rebecca Boyle again.

• 25:02Speaker 03

  We have one home, and I think it's a little sad to imagine that, like, well, it's too late. This place sucks now because we messed up. We got to go somewhere else.

• 25:12Noam Hassenfeld?

  And look, something terrible really could happen to Earth. But Mars is pretty apocalyptic right now. It's already kind of like what Earth might end up being after some sort of catastrophic event. So yeah, eventually, like, very, very eventually, we're going to have to leave Earth to survive. But it's not exactly the greatest justification for a mission to Mars right now, or even in 2040.

• 25:40Noam Hassenfeld?

  Still, there are other compelling reasons to learn to live far from Earth.

• 25:44Speaker 03

  It's a difficult place to go. It's a difficult place to be. It requires a lot of energy and risk, both in terms of life and capital, to do that at all.

• 25:55Noam Hassenfeld?

  Tackling the dangers of space leads to innovation. New technologies from phone cameras to wireless headphones to athletic shoes, they've all got their roots in the Apollo program. Plus, studying these extreme environments can really help people on Earth.

• 26:10Speaker 03

  A lot of research on things like bone density loss and microgravity has a lot of impact for people with bone density issues on Earth, like osteoporosis.

• 26:20Noam Hassenfeld?

  And finally, when it comes to science, there are certain things that people can do that rovers just can't.

• 26:26Speaker 03

  To me, it's the concept of kind of the known unknowns and the unknown unknowns.

• 26:31Noam Hassenfeld?

  Astronaut Anne McLean again.

• 26:32Speaker 03

  Rovers and unmanned aerial vehicles, those are very good for answering questions that we know what the question is. We know where we want to look. We know what we want to look for. But when you put a person in a situation, they have the ability to look off to the side and go, hey, what was that? What just caught my eye? Why does that look different right there?

• 26:53Noam Hassenfeld?

  This exact thing actually happened on Apollo 15 when astronauts were looking for lunar rocks. Just had speculated that finding this specific kind of rock called basalt would indicate volcanic activity.

• 27:04Speaker 03

  And Houston had put together where they thought they were going to find these rocks and they had done this whole mission and they were going back.

• 27:09Noam Hassenfeld?

  But then, one of the astronauts noticed something off the planned route.

• 27:13Speaker 03

  Out of the corner of his eyes, he sees what he knows to be a basalt rock.

• 27:18Speaker 02

  Oh, man. Hey, hold on one second.

• 27:22Speaker 03

  And he said, "We've got to go get that."

• 27:24Noam Hassenfeld?

  But NASA had already told them to end the mission, and he knew they wouldn't give him extra time to go check out the rock.

• 27:30Speaker 03

  And so they said, "Okay, let's just tell them our seatbelt's broken, so that we have to stop and adjust it."

• 27:35Speaker 02

  Can you get my seatbelt? Roger, Martha, you stop. She's coming on. Why don't you hand me your seatbelt?

• 27:42Speaker 03

  And he gets out of the rover and he runs over and he picks up this rock. Well, the other astronauts, like, "I don't want Houston to ask us any questions, so I'm just going to talk." And so you just hear him go, "Houston, I just want to paint this picture for you."

• 27:53Speaker 02

  There's all these small, fresh craters that we've commented on.

• 27:57Speaker 03

  It's just a beautiful landscape.

• 27:58Speaker 02

  They're just a concentration of rocks.

• 28:01Speaker 03

  And he just kept on talking, so that he'd go pick up the rock.

• 28:03Speaker 02

  Oh, I'm talking about maybe a foot, three feet diameter.

• 28:08Speaker 03

  That rock was very, very scientifically interesting.

• 28:11Noam Hassenfeld?

  This rock became known as the Seatbelt Basalt. And along with other samples, it pointed to the fact that the moon once had volcanic activity, the same activity that shaped the caves that could house a potential moon base. And Anne says that this rock is the type of thing that only humans would likely be able to find.

• 28:30Speaker 03

  But if we had relied on rovers, we would never have it.

• 28:35Noam Hassenfeld?

  So, given all of this, the compelling reasons to send humans to space for long periods of time weighed against the very real risks to health and human survival, most of which are honestly pretty much unknown, I wanted to ask the people I spoke to if they would take part in this new era of living in space. Some people, like Jonathan, are so dedicated to this idea of a multi-planetary future that they'd be willing to make a permanent move. I think many people like me, we are not afraid of even death. We would like to explore, to find something new. Jonathan told me that if his daughter was up for the trip too, he'd actually sign up for a one-way ticket to Mars. If there's an opportunity to go to a completely new place, I-

• 29:18Speaker 03

  Start something new, I die there, it's fine with me.

• 29:22Noam Hassenfeld?

  Other people like Anne were less into the idea.

• 29:25Speaker 03

  It is all about responsible exploration. And for me personally and the team at NASA, responsible exploration means that it's a two-way ticket.

• 29:33Noam Hassenfeld?

  I also checked in with Scott Kelly, who until recently held the American record for the longest space mission at 340 days.

• 29:40Speaker 06

  I do stupid things sometimes.

• 29:42Noam Hassenfeld?

  Scott said he'd be willing to go back, but not if it were permanent.

• 29:46Speaker 06

  I understand that there are people out there, most of them have probably never spent any time in space, that say they would be okay with living the rest of their lives on the surface of Mars in some kind of habitat. I am not one of those people, but I would watch that reality show because I think after a couple of years, it'd get pretty interesting.

• 30:09Noam Hassenfeld?

  What kind of interesting?

• 30:11Speaker 06

  Have you ever read the book The Lord of the Flies?

• 30:14Noam Hassenfeld?

  Sure.

• 30:16Speaker 06

  Probably that kind of interesting.

• 30:19Noam Hassenfeld?

  But for other people, the idea of going on any kind of long-term mission outside low Earth orbit just feels too risky. Like even Rebecca, who spent her career writing about the moon, who knows everything there is to know about it, she's not sure she'd actually want to spend time there.

• 30:37Speaker 01

  I think I would do it if I could be promised that I would be safe, but as we've been talking about, that's not a promise anybody can make. And so I don't think I would do it. As much as I would love that and to see the curvature of the Earth, which I spent so much time imagining and trying to write about and trying to recreate for people, I don't think if it came down to it, that I would actually strap myself into a rocket to have that experience.

• 31:04Noam Hassenfeld?

  It's easy to compare space exploration with the history of migration and exploration on Earth. You know, we're born to explore, that life always expands, that Mars is just the next logical step on our journey toward this future Star Trek universe. But it's also worth remembering just how risky a proposition this all is and the humans that are involved. This isn't just migration or exploration. This is learning to live in an environment that's actively trying to kill us in a whole bunch of different ways, all the time, most of which we don't really understand yet.

• 31:40Speaker 01

  Sometimes we need to ground ourselves in the reality that we have this planet that gave birth to us all and.

• 31:47Speaker 05

  I think we should remember that, you know, we have a lot to still save here and that we're made for it. And, you know, keeping both of those things in mind keeps us a little bit more feet on the ground, even as we look to the heavens.

• 32:15Noam Hassenfeld?

  This episode was reported and produced by me, Noam Hassenfeld. It was edited by Catherine Wells, Brian Resnick, and Meredith Hotnot. Music from me, mixing and sound design from Christian Ayala, fact checking from Zoe Mullick, and production assistance from Bird Pinkerton, Manding Nguyen, and Neil Dinesha. If you want to hear more from Rebecca Boyle, you should check out her book. It's called Our Moon: How Earth's Celestial Companion Transformed the Planet, Guided Evolution, and Made Us Who We Are. Special thanks to Chris Lainhart, Anna Schneider, and Rachel Hoover for their help. Thanks, as always, to Brian Resnick for co-creating the show with me and Bird. And if you have thoughts about this episode or ideas for the show, please email us. We're at [email protected]. And of course,

• 32:58Noam Hassenfeld?

  we'd love it if you left us a review or a rating. And if you're into supporting the show and all of Vox in general, join our membership program. You can go to vox.com/members to sign up. Unexplainable is part of the Vox Media Podcast Network, and we'll be waiting right here for you next time.