It’s time for the next Brains On debate! Our listeners sent in over 100 possible matchups and we whittled the list down to ten. You voted and chose this intense matchup from the depths of darkness, under the water and beyond our earth’s atmosphere. Who will prevail?

This epic episode includes three rounds of heated debate, two mystery sounds, and one winner.

More on deep sea exploration

More on space exploration

• Find out more about NASA’s Space Launch System here.

Audio Transcript

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HARPER: You're listening to Brains On! And we're serious about being curious.

MOLLY BLOOM: It's time.

MARK SANCHEZ: It's time.

SUBJECT: It's time.

MOLLY BLOOM: For the next Brains On! Debate. Our listeners sent in over 100 possible matchups.




MOLLY BLOOM: We whittled the list down to 10, right brain versus left brain.

SUBJECT: Dolphins versus octopuses.

MARK SANCHEZ: Day versus night.

MOLLY BLOOM: You voted and chose deep sea versus outer space.


HARPER: Which do you think is cooler?

SUBJECT: I think that outer space is better because there's much more potential to discover new things in outer space because space has no known limits, whereas the deep sea does.

SUBJECT: Deep in the sea is more interesting since it has not been explored much.

SUBJECT: I think space is cooler because the big bang was so cool.

SUBJECT: I like deep sea better than outer space because it has anglerfish. And I like anglerfish. They have a fishing pole and a light nose and [INAUDIBLE].

SUBJECT: There are strange animals that look cool.

SUBJECT: I think outer space is the best because of all the really cool things to explore out there like the Space Station and other planets.

SUBJECT: It has really cool planets, and suns, and galaxies.

SUBJECT: I like deep sea more than outer space because it has animals.

SUBJECT: There are plants and animals and other living things.

SUBJECT: I think outer space is cooler because in space, you can basically fly. And you can see better than underwater.

SUBJECT: I think deep sea is cooler because there is lots of weird things and big fish. And there might be some new animals and some parts of the ocean are not discovered.

MOLLY BLOOM: The listeners holding those strong opinions were Oscar from Minnesota, Nichi-kun from Vermont, Wesley from California, Matthew from Washington, Evan from California, Penelope from North Dakota, Rose and Jane from California, Alex from Colorado, Axer from Pittsburgh, and Jasper from Banff National Park.

Today we're going to take this heated debate into the depths of darkness under the water and beyond our Earth's atmosphere. Who will prevail?

HARPER: Let's get started.


MOLLY BLOOM: You're listening to Brains On! from American Public Media. I'm Molly Bloom. Here with me today is eight-year-old Harper from Palm Desert, California. Hello, Harper.


MOLLY BLOOM: Harper is the one who sent in the winning debate match-up of deep sea versus outer space. So Harper, how did you come up with this match-up?

HARPER: Well, first of all, I really like dolphins. So that gave me the deep sea side of the debate. And for the outer space, I really like aliens.

MOLLY BLOOM: Tell me about your love of aliens. Where does that come from?

HARPER: It came from listening to your show about life on other planets.

MOLLY BLOOM: Oh, cool. What is your favorite thing about space?

HARPER: My favorite thing about space is that it's so vast and we know so little about it.

MOLLY BLOOM: And how about the ocean? What's your favorite thing about the ocean?

HARPER: Dolphins.

MOLLY BLOOM: Dolphins.

HARPER: Dolphins are my favorite thing in the universe other than cats.

MOLLY BLOOM: Whoa. So why? Why are dolphins so cool?

HARPER: I like the little squeak sounds that they make when they're communicating with each other.

MOLLY BLOOM: Well, I think you are the perfect judge for today's debate. And I know even though you love dolphins, you also love aliens. So we're counting on you to be fair and impartial when considering the arguments. Are you ready to get started?

HARPER: I'm ready to get started.

MOLLY BLOOM: Arguing in favor of deep sea, we have Brains On! Producer Mark Sanchez.

MARC SANCHEZ: Hello, everybody. And Harper, I have a special message for you. I hope this works.


That's just a little dolphin noise. They're saying hello to not to sway the vote or anything.


MARC SANCHEZ: But there's some dolphins.

MOLLY BLOOM: And arguing in favor of outer space, we have Brains On! Producer Sanden Totten.

SANDEN TOTTEN: Hey. Space is the place that's going to win this race. And if you love dolphins, space is so vast. We could conceptualize that maybe there's an entire planet just dolphins. Think on that.

MOLLY BLOOM: Wow. So we're going to start with opening statements. We're going to flip a coin to see who goes first. Sanden, you can call it. Heads or tails?


MOLLY BLOOM: It's tails. So Sanden, that means you get to choose. Do you want to go first or second for your opening statement?

SANDEN TOTTEN: I'll go first.

MOLLY BLOOM: OK, take it away.

SANDEN TOTTEN: The beautiful thing about space is that anyone can explore it. You don't need to hold your breath, or plug your nose, you don't need a submarine. You don't even have to get wet. All you need is a dark sky, and your eyes, your peepers, in your face. That's how early astronomers like Aristotle and Copernicus did it. And if you want to get more advanced, we've got cool telescopes. We've got satellites, probes, and even spaceships.

And yeah, exploring space isn't easy. It's really far away. It's cold. It is deadly. But those obstacles, they push us to be better, to be smarter, to come up with greater and greater technology. In fact, space pushed us to invent rockets, and spaceships, and robots that can explore other planets by themselves. Well, mostly. We do program them. And space technology has led to things that all of us use, not just in space, but here on Earth, like scratch-resistant glasses, comfy tennis shoes, cordless vacuum cleaners, cell phone cameras, and even baby food.

All that stuff came from things we're inventing to help explore space. Plus space is just cool. You can have planets with two suns, black holes that warp space and time, places where it could rain diamonds. Space is full of surprise and wonder. Long after we've plumbed the depths of the oceans and we've seen all the coral and jelly whatevers, we'll still be exploring space finding crazier planets, bigger stars, and maybe one day, alien life. Choose team space because with team space, the sky isn't the limit. It's just the beginning.

MOLLY BLOOM: Thank you, Sanden. Marc, your opening statement.

MARC SANCHEZ: Thanks. We can all admire what's above us in space. The unfortunate fact is very few of us will ever get the chance to explore another planet or moon. But my friends, the ocean is here for everyone. Dive into the ocean and gain firsthand knowledge of different ecosystems, completely different worlds that are held right here on Earth. I'm talking about worlds that are almost entirely unexplored. Oceans cover 71% of the Earth. And yet, we have only explored 1% of those waters.

New creatures, real life forms, are being discovered all the time. With each dive, we can learn about life, where we came from, and how life got started on this planet in the first place. Of course, we have a lot to learn from looking up and dreaming about the stars. But right now, we have the opportunity to take our heads out of the clouds and touch the water. The virtually unexplored waters of the deep sea are here and waiting to share their secrets.

MOLLY BLOOM: Two very compelling opening statements. Harper, you do not have to say it out loud right now, but please mark down a point for whomever you think had the most compelling, interesting, coolest opening statement. And listeners, you can do this on your own as well. Who had the best opening statement? All right. Did you mark it down, Harper?


MOLLY BLOOM: Was it a hard decision?


MOLLY BLOOM: OK, so we're on to round one. This time, Marc, we will start with you.

MARC SANCHEZ: We've been jumping into the ocean longer than recorded history. Hold your breath, swim around a little bit, and come up for air. But we can only go so deep on our own. A recent scuba diving record was set at just over 1,000 feet. But the Professional Association for Diving Instructors suggests we should only venture about 130 feet down to be safe. And that has a lot to do with hydrostatic pressure. Let's talk about that for a minute.

Hydrostatic pressure is the weight you feel from water when you're submerged. As you go deeper, you put more water between you and the surface. More water means more weight. And that weight is pushing at you from all sides. If you've ever jumped into a pool and felt your ears hurt on the way to touching the bottom, that's hydrostatic pressure pushing up against your eardrum. And be careful. It can burst it. We've figured out ways to help our bodies adjust to hydrostatic pressure, but only to limited depths, depths nowhere near the deep sea.

The deepest known spot on Earth is in the Pacific Ocean. It's called the Mariana Trench. It bottoms out at 35,814 feet. That's about 7 miles below sea level. The tallest mountain on Earth, Mount Everest, is only 29,029 feet. So tiny. If Mount Everest were placed in the Mariana Trench, it would still be over a mile below the sea.

The Mariana Trench was first hinted at on a mission by the HMS Challenger. The ship set out in 1872 and was the first ship equipped for scientific research. Its missions are often referred to as the beginning of modern oceanography. Part of the research being done on the HMS Challenger was to take measurements at the bottom of the ocean. Every 140 miles, they would throw a big lead weight over the side. It was attached to a long piece of rope called a sounding rope.

Once the weight hit the bottom, they measured the length of rope and calculated the depth. In 1875, that weight kept dropping, and dropping, and dropping, and still dropping. The crew recorded a depth of 4,475 fathoms. A fathom is equal to 6 feet. So 4,475 fathoms is almost 5 miles deep.

And to get that far down, or even remotely close, we need the help of submersibles. Like submarines, submersibles let people go underwater without the need of special breathing equipment. Submarines operate under their own power to get from place to place. And they provide a steady stream of air to breathe. Submersibles, however, need the help of another vessel to take them to a spot and drop them in the water.

Unlike most submarines, submersibles are built to go down. They're made of extremely thick materials to withstand enormous hydrostatic pressure. And key for scientific research, submersibles have windows, and lights, and cameras to help observe deep sea life. An early submersible pioneer was William Beebe. In the 1920s, he was already a famous ecologist, naturalist, and explorer.

He found himself on the Galapagos Islands following in Charles Darwin's footsteps. Surrounded by all sorts of new species on land and in the sea, Beebe actually invented helmet diving. And he was the first coral reef ecologist.

WILLIAM BEEBE: Oh, well, this coral is beautiful. But say, what else is down here? Well, there has to be more.

MARC SANCHEZ: Beebe tried to come up with a design for a sea craft that could go underwater and withstand the pressure of the deep sea. But unsurprisingly, this proved difficult.

OTIS BARTON: Hello. Hello.

MARC SANCHEZ: Enter engineer Otis Barton.

OTIS BARTON: Need some help with your design, Beebe? How about making it spherical?

WILLIAM BEEBE: A sphere, eh? You mean like a ball or something?

OTIS BARTON: Naturally. A sphere will help distribute the ocean's weight evenly so that this submersible won't get crushed by hydrostatic pressure. And we'll make it of really, really thick steel. Uncrushable.

MARC SANCHEZ: Otis Barton's uncrushable sphere measured only about 4 feet in diameter, so 4 feet from one side to the other. It looked like a giant cannonball with three small porthole windows to observe the sea. It was connected to ships on the surface by cables, which were also used for electricity and a phone line. Otis Barton dubbed his creation the bathysphere.

Barton said he would design and pay for the construction of the bathysphere on one condition.

OTIS BARTON: I get to go down with you in the bathysphere.


OTIS BARTON: Well, that's the dealio.

WILLIAM BEEBE: Are you positive?

OTIS BARTON: I'm an excellent sailor. And I love the company of marine life much more than people actually.

MARC SANCHEZ: Barton wasn't the friendliest guy. He was kind of a loner who was more interested in making underwater movies than actually getting along with people. And to top it off, Barton got seasick. During more than one test dive, the bathysphere had to be hauled up out of the water because, ugh, Barton had hurled.

WILLIAM BEEBE: Barton, are you kidding me?

OTIS BARTON: I'm an, ugh, excellent sailor.

MARC SANCHEZ: And remember, this thing is tiny. Barton and Beebe were both in there sitting on these little mats with their legs all scrunched up. But even with all these problems, this unlikely duo managed to stick it out.

On August 15, 1934, the hatch was shut for their deepest dive. After a few years of trial and error, Beebe and Barton were bolted into the bathysphere and dropped in the waters off the Nonsuch Islands in Bermuda.

WILLIAM BEEBE: Not feeling too seasick today, Otis?

OTIS BARTON: I'm an excellent sailor.

MARC SANCHEZ: The pair descended to over 1/2 mile down, 3,028 feet. They shattered the previous record, which stood at only 383 feet. They could have kept going too. But 3,028 feet was the length of their cable. At that depth, the pressure is 120 times greater than it is here on Earth, which means a leak in the bathysphere could have sent water shooting into the submersible with enough force to cut right through a body. One of their windows did actually start to crack. But the bathysphere held up.

Beebe eventually wrote a book about his adventure called Half Mile Down. It was wildly popular and helped get others to think about the deep sea.


Another significant voyage happened about 25 years later when Jacques Piccard and Don Walsh descended into the deepest part of the Mariana Trench. In January of 1960, both men squeezed into a submersible they called the Bathyscaphe Trieste. They dove 35,800 feet into an area of the trench called Challenger Deep. Once they reached the bottom, they couldn't see much because when they landed, the ocean kicked up a huge cloud of debris, making it so they couldn't see outside their window.

And thanks to our old frenemy hydrostatic pressure, a crack began to form in the window. Not something you want to see 7 miles below the sea. So Walsh and Piccard had to ascend back out of the Mariana Trench after only having spent about 20 minutes on the bottom. We've sent more people to the moon than we've ever sent down to the Mariana Trench. It took more than half a century after the Trieste's dive for somebody to go down again.

In 2012, filmmaker James Cameron decided to take the plunge. Cameron has had a long fascination with the deep sea. He's the guy responsible for underwater blockbuster movies like Titanic and The Abyss. He crammed himself into a submersible called Deep Sea Challenger and descended into the Mariana Trench. He made it down 35,756, feet the deepest solo trip ever.

He spent a few hours hovering in Challenger Deep, collecting samples, and he even made a movie about it. Hopefully, we won't have to wait another 50 years for the next mission down. I mean, the moon is cool and everything. But the trench, it's right here.

MOLLY BLOOM: Thank you, Marc. Harper, what was the most fascinating fact in Marc's first round?

HARPER: I've heard about the first trip down to the Mariana Trench. But I did not know that they could not see out the windows. I thought that they could see out the windows because that's what I heard. But I guess I was wrong.

MARC SANCHEZ: Don Walsh describes it as a milky soup, I think. So it's just like-- looked like a big cloud of fog that he couldn't see out at all.

MOLLY BLOOM: OK, so let's see if Sanden can top that fascinating fact. You ready, Sanden?


MOLLY BLOOM: Here you go.

SANDEN TOTTEN: Very well done, Marc. That was super cool. And yeah, exploring the deep sea has taught us some pretty cool things. But space gave us rockets. And rockets may have actually helped us get a little closer to peace right here on Earth. Let me explain.

Rockets aren't that old. In fact, less than a hundred years ago, if you told somebody you were trying to build a rocket, they'd straight up laugh in your face.

TODD BARBER: The word rocket in the 1930s had a giggle factor. You would never get your mission funded if you said I was working on a rocket because rocket was science fiction. It was Buck Rogers stuff. It could never happen.

SANDEN TOTTEN: That's Todd Barber, an actual rocket scientist for NASA's Jet Propulsion Laboratory here in California. He says the reason people thought rockets were impossible was simple, a little thing called gravity.

TODD BARBER: If you've ever tried to get out of bed when you're really tired, or try to dunk a 10-foot basketball goal-- my only hope for that is to go to Mars by the way with it's 3/8 gravity. But the Earth's gravity is really strong. As hard as I try, I can't jump more than a foot or 2 off the ground. So just think of a heavy rocket, how much energy it has to expend to be able to get to low-Earth orbit, or outside of Earth.

SANDEN TOTTEN: Lucky for us, people didn't let this stop them. In fact, the founders of Todd's workplace, the Jet Propulsion Lab, helped invent some of the first rockets. The key is to create fuels that burn up fast and push out a lot of exhaust when they do. Rockets channel that exhaust out their base. That's where the giant plumes you see during a rocket launch come from. Todd says these plumes are actually what's pushing the rocket up. It's Thanks to Newton's third law. That's Isaac Newton, by the way. For every action, there is an equal and opposite reaction.

TODD BARBER: The thrust you throw out-- the material you throw out of the back of a rocket engine, you get a recoil that essentially, the shuttle itself recoils from all that stuff flowing out. And the recoil pushes it up. You just keep flowing material out the back at very high speed. And that equal and opposite reaction forces your vehicle up and away.

SANDEN TOTTEN: OK, so that's how a rocket works. But how does that lead to more peace? Well, in the 1950s, the United States and the Soviet Union, today known as Russia, they were locked in something called a Cold War. They weren't fighting directly. But things were tense and both sides were afraid the other was going to attack. It was not good.

During this time, both countries were obsessed with sending things to space. NASA's spaceship expert Nujoud Merancy says the Soviets got there first on October 4, 1957 by launching something called Sputnik.

NUJOUD MERANCY: And that was just a very small satellite. It went around the world and it beeped. But what that did is with the Sputnik satellite, it made space possible.

SUBJECT: Today, a new moon is in the sky, a 23-inch metal sphere placed in orbit by a Russian rocket. You are hearing the actual signals transmitted by the Earth-circling satellite, one of the great scientific feats of the age.

NUJOUD MERANCY: So the whole point of Sputnik was to show that you could have something to orbit the Earth. And that's what it did. And you could go outside anywhere in the world. And when Sputnik passed overhead, with a hand-held radio listen to the beeps it was putting out. So that's all Sputnik actually did.

SANDEN TOTTEN: After Sputnik, the US and Soviet Russia space race was on. Both sides were competing to be the best at exploring outer space. Shortly after Sputnik, the US launched their own satellite called Explorer 1. And next, both sides started working on sending people into space. The Russians were faster once again. Both sides were eager to win the space race. And in the process, they started using existing technology, specifically rockets built for the military.

NUJOUD MERANCY: They were actually converted intercontinental ballistic missiles. So what had been used essentially as a weapon of war was being converted into more or less a weapon of peace, which is human space exploration.

SANDEN TOTTEN: So that's pretty cool. And so far, if you're worried that Team America has really been behind in this space race, well, get ready. We caught up in a big way. The United States was the first to land a man on the moon.

NEIL ARMSTRONG: It's one small step for man, one giant leap for mankind.

SANDEN TOTTEN: As the years went on, both the US and the Soviet Union started realizing they could learn from each other and help each other get better at this space stuff. In fact, in 1975, the two countries did something amazing. They both sent up ships around the same time and had them link up in space. Once the two ships were connected, the astronauts inside could actually reach through a portal to greet each other. There, surrounded by cold darkness far above the Earth, Russian astronauts and American astronauts actually shook hands.

SUBJECT: Around the world, millions watch and listen as the two spacecraft become one. Now, they wait for the next dramatic event, the meeting of Soviet and American crews.

SANDEN TOTTEN: It was a huge moment. And over time, things only got more and more cooperative between the two space programs. The Cold War eventually ended. And today, US and Russian scientists work together regularly on the International Space Station. In fact, US astronauts get rides to the Space Station on Russian rockets. So even though we started as competitors, thanks to space, we learned to work together. Space really does bring out the best in all of us. And this story is just one example of that.

MOLLY BLOOM: Thank you, Sanden. And Harper, are you-- would you ever want to visit space do you think?

HARPER: If I got to bring my dog, then I would. If I didn't get to bring my dog, then I wouldn't.

SANDEN TOTTEN: Imagine zero-G fetch. How cool would that be?

HARPER: That would be crazy just watching him floating around trying to run in zero gravity. And he would just be spinning around in circles. Where's my ball? Where's my ball?

MOLLY BLOOM: OK, you heard Marc's first round, and you heard Sanden's first round. I want you to think about what you thought was cooler. And I want you to give one of them a point on your sheet there. And if you need a little more time to think it over, we'll be right back after these messages.

SUBJECT: Space, think it's great? Think again. Space isn't exactly hospitable to human bodies. First off, you can't breathe in space. The low atmospheric pressure forces the air out of your lungs and you'll suffocate. And if that weren't enough, the moisture on your eyes, tongue, and body would begin to boil and cause your skin to inflate like a balloon. And don't think about wandering too far from Earth. If you're within a few million miles of the sun, you'll cook at 248 degrees Fahrenheit.

Or if you're between galaxies, minus 454 degrees Fahrenheit will freeze your toes off faster than a popsicle dipped in liquid nitrogen. You can get zapped by cosmic radiation, crushed by the gravitational pull of a gas giant, or spaghettified as your body gets strung into a single string of atoms along the event horizon of a black hole. Better to leave space to the aliens and asteroids and go to the beach instead. Paid for by The Oceans Are Way Better Than Space League.


SUBJECT: Only one place has the courage, nay the audacity, to be completely unboring all the time, outer space. Space has been working tirelessly to blow your mind since the big bang, 13.8 billion years ago. With planets like Mars, which has a volcano 2 and 1/2 times bigger than Mount Everest and blue sunsets, or Venus, where it snows metal, or Saturn with 150 moons. Like shiny things? Space had more stars than there are grains of sand on Earth. Ga-bling.

Like the dark? Space has black holes so dense, even light can't escape. Totally goth. Like working out? Try benching a neutron star? A single spoonful weighs roughly a billion tons. Pump that, bro. When it comes time to pick sides, choose space. It's the coolest. Literally. I mean, like it's negative 454 degrees Fahrenheit up there. Brrr. Paid for by Team Space and probably some aliens because they think space rules too.

MOLLY BLOOM: Wait a minute. You guys bought ad time in our own show?

SANDEN TOTTEN: Well, Marc started it. I had to defend myself.

MARC SANCHEZ: This is the versus episode, you guys. We'll do whatever it takes. Besides, you heard for yourself, I didn't pay for mine.

MOLLY BLOOM: Guys, guys, can we focus on the issues please?

MARC SANCHEZ: All right. I guess.

MOLLY BLOOM: The next issue at hand can earn you both a point. It's time for the mystery sound.

SUBJECT: Mystery sound.

MOLLY BLOOM: I have one for each of you. Marc, here is your mystery sound.


Any guesses, Marc?

MARC SANCHEZ: I know it's underwater because I'm deep--

MOLLY BLOOM: You're the ocean.

MARC SANCHEZ: Team Deep Sea. So yes. It's underwater. But I also heard something percussive, something kind of rhythmic. It's not a rock. It's an animal in the ocean. And I'm going to say it's-- I don't know the name of it, like a clapping shrimp.

MOLLY BLOOM: A clapping shrimp. Harper, this is not a point for you. But I think you should get to guess too. What do you think it is?

HARPER: I think it's someone pouring water out of one of those-- out of a bucket into the ocean.

MARC SANCHEZ: Ooh, maybe I should change my guess.

MOLLY BLOOM: Those are both good guess. So we have a clapping shrimp and water out of a bucket into the ocean. OK, so we'll keep that in mind. We'll find out the answer in a little bit. Sanden, here is your mystery sound.

SANDEN TOTTEN: Lay it on me.


MOLLY BLOOM: OK, Sanden. Any guesses?

SANDEN TOTTEN: OK, so that was really percussive. It sounds like rapid fire popcorn popping.

MOLLY BLOOM: Space popcorn.

SANDEN TOTTEN: It could be space popcorn being heated by microwave rays from space. But I think maybe that is radio waves. And so my thought is maybe that "brrr" sound is these waves getting picked up by a radio or something, or some kind of telescope of some distant cosmic event like a star exploding, or like a galaxy farting, or something.

MOLLY BLOOM: Excellent guess, Sanden. Harper, do you have any thoughts about what that might be?

HARPER: I think it might be maybe three small asteroids tumbling around together.

MOLLY BLOOM: Excellent guess.

HARPER: Maybe a black hole.

SANDEN TOTTEN: Like an asteroid kind of like crashing, like asteroid traffic or something.

MOLLY BLOOM: OK, those are all good guesses guys. We will be back with the answers right after this.

SANDEN TOTTEN: Psst. Guys. Don't tell Marc I'm doing this. I'm not doing it to gain your sympathy. I promise. But we are giving away a super cool book. It's called The Seven Wonders of the Solar System. And it's full of fascinating facts about the patch of space we call home. You can enter to win your copy by visiting You have to be 18 or older to enter and to pick five lucky winners and send them the book. Go, space. Space rules.

MARC SANCHEZ: Sanden, I'm literally right here listening to you. And you may be giving away an awesome book about space, but do you know what doesn't exist in space? Farts. There are lots of farts here on Earth, both on land and in the sea. And we're having lots of fun hearing about them as we prepare for our upcoming episode about animal farts.

We want to hear what you think those farts sound like. Make a recording of your best fart guess. Here are a couple awesome fart recordings we've gotten so far.

SUBJECT: This is a bear fart sound, I think. [FART SOUND]

SUBJECT: This is how I think a T-rex fart sounds like.


MARC SANCHEZ: Get creative with your farts, people. And send your fart recordings to

SANDEN TOTTEN: I just want to say, Marc, while I agree there are probably no farts in the vacuum of space, I'm sure astronauts fart up there. And I would love to hear someone give us a rendition of what an astronaut fart would sound like. I kind of imagine a heroic fart.

MOLLY BLOOM: We started the Brains honor roll to thank all the kids who send us fart sounds, and mystery sounds, and drawings, and high fives, and questions. We'll announce the most recent group to be added to the brain's honor roll at the end of the show.

HARPER: You're listening to Brains On! From American Public Media. I'm Harper.

MOLLY BLOOM: And I'm Molly. We are in the midst of a heated debate here at Brains On! Headquarters between deep sea and outer space. Harper, how do you think it's going so far?

HARPER: So far, space is winning.


SANDEN TOTTEN: Yes. Whoo. Where my asteroids at?

MARC SANCHEZ: Where are my dolphins? Please. Dolphins, save me.

MOLLY BLOOM: Well, we'll see who gets a point with these mystery sounds. Let's hear them one more time. Marc, you first.


Any new thoughts, Marc?

MARC SANCHEZ: I'm pretty stumped. I think I said clapping shrimp before. And I have a feeling that's wrong. But I'll stick with it.

MOLLY BLOOM: Here with the answer is Craig Radford. He works in bio acoustics at Auckland University in New Zealand.

CRAIG RADFORD: This is the feeding sound of a sea urchin. It's a sound that they don't make on purpose. It's just a result of the animal's anatomy and how it feeds on algae or on rocks.

MOLLY BLOOM: OK, you were close. It was an animal--

MARC SANCHEZ: It was an animal.

MOLLY BLOOM: In the ocean. But I don't think you get a point for it. What do you think, Harper? Does he get a point for that?

HARPER: I think we should give him at least half a point.

MOLLY BLOOM: Harper, you're the scorekeeper. So if you give him half a point, he gets half a point.

MARC SANCHEZ: Shrimps and sea urchin, they're pretty much the same thing, right? Am I right?

MOLLY BLOOM: I mean, you can eat both of them.

SANDEN TOTTEN: I think one costs a lot more on a sushi menu though.

MARC SANCHEZ: That's true. That's true. Thank you for half a point.

SANDEN TOTTEN: People at home, you don't have to give Marc the half point if you don't want to. It's up to you. The power is yours.

MOLLY BLOOM: OK. So sea urchins, or kina, which is the native name for these animals in New Zealand, are super cool. They can be found in all climates in a super wide range of depths, including the deep sea. The sea urchins you might be most familiar with basically look like dark balls covered in spikes. Now this sound we just played for you was detected in the ocean before scientists knew what it was. It was a true mystery sound.

CRAIG RADFORD: It was a sound in the ocean first described in the late '60s, early '70s, around Australia and New Zealand. And no one really knew what it was.

MOLLY BLOOM: A physicist theorized that it could possibly be a sea urchin given the sea urchin's anatomy, that somehow, their bodies were functioning as resonators for sound. It took decades, but Craig and his team were the first to prove that this sound was, in fact, coming from sea urchins. They first heard the sound while doing unrelated underwater recordings.

CRAIG RADFORD: We were getting the same sounds on the recordings here in North Eastern New Zealand. And one of my sites had a lot of urchins at it. So we basically went and collected a whole lot of urchins, put single urchins of different size classes in tanks by themselves, and put underwater microphones in these tanks. And we recorded their feeding sounds.

MOLLY BLOOM: So the mystery was solved.

SUBJECT: Brains On!

MOLLY BLOOM: Sanden, let's hear your mystery sound again.


OK, Sanden. Any new guesses?

SANDEN TOTTEN: Did you ever see one of those little kid lawnmower toys that had the balls pop up?


SANDEN TOTTEN: Is it one of those but with an alien pushing it?

MOLLY BLOOM: Yes. Oh my gosh. How did you guess?

SANDEN TOTTEN: I think I'm going to stick with my idea that this is some form of radio waves from some distant space event that we've picked up and it translates into these kind of bursts of energy that we hear a sound.

MOLLY BLOOM: And Harper thought it was asteroids tumbling around and hitting each other. So here with the answer is Jay Melosh. He's a geophysicist from Purdue University.

JAY MELOSH: That sound that you just heard was the sound of dust flying off comet Tempel 1 as the Stardust spacecraft passed about 60 miles away from it in 2010.

MOLLY BLOOM: So Sanden, you were not right. But actually, Harper was pretty close.

SANDEN TOTTEN: That's awesome. Way to go, Harper.

MOLLY BLOOM: So I guess, Harper, I guess you could decide if your points get to go to Sanden.

HARPER: I think I'm going to give Sanden half a point.

SANDEN TOTTEN: I get your half a point?


SANDEN TOTTEN: You played-- you played on our teams when you get-- that's awesome. Thank you.

MOLLY BLOOM: That's excellent. Jay was one of the investigators in the mission that actually recorded this. Stardust was unmanned. But Jay was one of the earthlings who helped to design, and execute the mission, and analyze the data collected. And Jay was part of this mission because he studies collisions.

JAY MELOSH: My specialty is impact violence in the solar system. I'm interested in collisions of planets, in comets, and in other phenomena that involve collisions between solid bodies in the solar system.

MOLLY BLOOM: One of the cool bonuses of his work is that Jay has an asteroid named after him. Not too shabby. So anyway, this Stardust spacecraft had very sensitive impact detector on it. And as bits of dust flew off the comet, it hit the spacecraft.

JAY MELOSH: We listened to that recording many times over. When you listen to it, you hear kind of bang, bang, bang, bang, it's quiet for a bit, and another bang, bang, bang, bang, bang, bang, then a bit of quiet, and then a bang. And then it picks up again. And that already tells us that the dust is not distributed uniformly around the comet. It comes in clumps.

MOLLY BLOOM: Comets are made up of ice, dust, and frozen gases.

JAY MELOSH: As it gets close to the sun, the ice is-- that evaporates. And as it evaporates, it streams away from the comet. That's what makes the cometary tail. The word coma in Latin means hair. And when these things were observed back in history, people called them hairy stars. The cometary tail, the hair of the comet, is actually made up of mainly dust. There's also another tail that's generally fainter that's made of gas that is streaming away from the sun as well. If you catch a comet right, you can actually see two tails, the gas tail, and the dust tail.

MOLLY BLOOM: So as the ice evaporated on Tempel 1, bits broke off the comet. And those bits hit the Stardust spacecraft, allowing Jay and his team to analyze its makeup. OK, so each of you got half a point for your mystery sounds, thanks to Harper's generosity.

SANDEN TOTTEN: Not bad. Thank you, Harper.

MARC SANCHEZ: Thank you. Thank you.

MOLLY BLOOM: All right. So while we bask in that knowledge, we're going to play some more messages. Wait, more messages?

SUBJECT: Team Deep Sea doesn't want you to know the truth about hydrostatic pressure. Sure, submersibles can explore the depths of the deep sea. But humans can't bear the weight. And you, guess what, are a human. So my friends, if you want to frolic in the Mariana Trench, tough crabs.

At a mere 33 feet below sea level, you'd double the weight of Earth's atmosphere. A leak in William Beebe's bathysphere, a 1/2 mile down could shoot a jet of water with enough force to saw off your hand. And at the depths of the Mariana Trench, 7 miles below sea level, hydrostatic pressure would reduce you to pulp before you could say rubber ducky. A vote for outer space is the perfect way to take some pressure off. Paid for by the Space Superiority Society.

SUBJECT: The deep sea is the clear and obvious choice for exploration. Oceans are accessible to everyone and full of life, life we know about and life still to be discovered. Between the years 2000 and 2010, the Census of Marine Life counted nearly 250,000 different species living in the oceans of the world. That's about 250,000 more than we found in space ever.

And there's still so much about the ocean that we don't know. It's estimated that for every one ocean life we know about, there are four yet to be discovered. Go on. What are you waiting for? That water is fine. Dive in and vote for the deep sea.

SUBJECT: Possibly paid for by all the fish in the sea, including those cute ones in the Nemo movies. Marine biologists and oceanographers everywhere.

MARC SANCHEZ: I'm Marc Sanchez and I approve this message.

MOLLY BLOOM: And we're back. Really pulling out all the stops, guys, this time around. Very impressive. But now, it's time for the lightning round. Three fascinating facts from each of you. We'll go back and forth. We will start with Sanden. On your mark, get set, go.

SUBJECT: Lightning.

SANDEN TOTTEN: Ever hear of exoplanets? These are planets in other solar systems that we've observed with telescopes. Some are just plain amazing. There's one that seems to be covered in burning ice. Think on that for a minute, burning ice. Extreme pressure and heat caused this phenomenon. We think another has winds blowing 7 times faster than the speed of sound. And it possibly rains silicate particles, which is like glass rain. Then there's even one that's suspected to have a surface made up of graphite and diamonds. Exoplanets are awesome.

SUBJECT: Lightning.

MARC SANCHEZ: OK, I want to talk about bioluminescence. The farther you go down in the sea, the fewer colors of light you'll see. Reds go first, then yellows, then greens, dark blues, and deep violets lead to pitch black. And what would you want in an environment that was dark all day and night? A light, right? Bioluminescence is the ability for animals to produce their own light. A few creatures do it on land. Hello, fireflies. But there are lots of bioluminescent creatures in the deep sea.

Some animals have the ability to make their own light while others rely on bioluminescent bacteria to light the way. The bacteria will live in fish, for example, and light up as either a way to attract prey or defend being eaten. Bioluminescence, it's quite a light show.

SUBJECT: Lightning.

SANDEN TOTTEN: There may be aliens in our midst in our very own solar system. Jupiter's moon Europa is covered in ice. But there's good evidence that under that ice, there's a vast, wait for it, ocean. Beneath that ocean is a rocky surface that could very well have hot spots. These are thermal vents that release energy into the water. Scientists think these same elements help form life here on Earth. That's rocky materials, liquid water, and a source of energy.

So if life developed here on Earth from those ingredients, could it have also developed under the ice crust of Europa? Maybe. Scientists are actually working on a mission right now to learn more. It's called the Europa Clipper. And maybe they'll find out that we're not alone in our own solar system. Maybe there's an entire deep sea moon.

SUBJECT: Lightning.

MARC SANCHEZ: There are so many fascinating creatures down in the deep sea. But I want to focus in on just one, the anglerfish. The deep sea anglerfish has a gigantic mouth full of these long, spiky teeth. It looks vicious. And these teeth mean business. The anglerfish has a small golf club-shaped protrusion sticking out of its head. And this golf club glows thanks to bioluminescence. The glow lures the other fish over to investigate. They're like, bright light. What's that? Can I eat it? And before you can say fish fail, the deep sea anglerfish chomps down for a tasty snack.

SUBJECT: Lightning.

SANDEN TOTTEN: So if you think you've had a lot of birthdays, get this. The universe has had 13.8 billion birthdays. That's how old we think the universe is. Current estimates are that it is at least 46 billion light years across. That means it would take something traveling at the speed of light 46 billion years to cross it. Talk about a really long road trip. I hope you went to the bathroom first.

And it's expanding. There's so much universe out there that chances are there are things we haven't even dreamt of waiting to be discovered. Could there be a planet of gold? Moons that zigzag through the sky? Wormholes that allow you to jump from one galaxy to another? Who knows what we'll find? And you can't compete with that in terms of sheer wonder.

SUBJECT: Lightning.

MARC SANCHEZ: I'm going to give you five names and I want you to tell me how they are related. Ready? Atlantis. Challenger. Columbia. Discovery. And endeavor.

HARPER: I've heard of two of them.

MARC SANCHEZ: And what would you say they have in common?

HARPER: They're all spacecrafts?

MARC SANCHEZ: That's right. They are famous space shuttles. But first, first, they were famous ships, ships that explored the ocean. With this marine tribute, it's clear even NASA knows there would be no space exploration without the sea.

SUBJECT: Lightning.

MOLLY BLOOM: Excellent lightning round battle, you guys. OK, Harper, and all of our listeners out there, think about who had the three more fascinating facts. And I want you to reward a point.

SUBJECT: Ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, Brains On!

MOLLY BLOOM: We have one final round before the closing statements. Marc, we will start with you.

MARC SANCHEZ: It's always fun to hear about new creatures being discovered in the ocean. The water is close to freezing down there, there's little oxygen, and hydrostatic pressure. And there's one type of organism that's being discovered at a faster rate than any other, the tiny microbe. Bacteria. It wasn't until very recently in the last 40 years that we learn bacteria could live and thrive without the sun. They were found in the dark, deep sea. And that's where Nicole Dubilier studies them.

NICOLE DUBILIER: I'm a marine biologist. And I work at the Max Planck Institute for Marine Microbiology in Bremen, Germany.

MARC SANCHEZ: The bacteria that Nicole studies take part in what's called symbiosis. That's when two different organisms live in or near each other. And at least one of them gets some sort of benefit from the other. Maybe you've seen a cattle egret perched on the back of a cow. While that white bird gets a free ride, it also pecks at the ticks in a cow's ears. Win-win. Symbiosis.

NICOLE DUBILIER: The type of bacteria that I work on are able to feed their animal hosts, they provide them with food, because they can fix CO2--

MARC SANCHEZ: Carbon dioxide.

NICOLE DUBILIER: Into carbon compounds like sugars and carbohydrates and pass that on to their hosts.

MARC SANCHEZ: These tiny microscopic organisms are the first link in a deep sea food chain. In sunlight, the first link might be plants or algae. They take energy from the sun, combine it with carbon dioxide from the air, and produce sugars and carbohydrates to help it or other animals live. We know this process as photosynthesis. What Nicole is describing is pretty much the same thing, except--

NICOLE DUBILIER: In the deep sea, there is no light. The bacteria there that are at the base of the food chain are chemosynthetic bacteria.

MARC SANCHEZ: Aha, chemosynthesis.

NICOLE DUBILIER: Chemo stands for chemicals. So they're using chemicals as an energy source to fix CO2 instead of light. And they're coming from hot vents at the bottom of the ocean floor.

MARC SANCHEZ: Those hot vents were first discovered in 1977. They're called hydrothermal vents. When ocean water seeps into cracks in the Earth's surface, it mixes with hot magma. The newly heated water then rises back up through hydrothermal vents to begin that food chain. Hot meal coming through.

NICOLE DUBILIER: So if you go to a hydrothermal vent, then most of the community that you see there is based on symbiosis between the animals and these chemosynthetic bacteria. And they harbor them, depending on what kind of animal they are, in different organs of their bodies.

MARC SANCHEZ: Nicole has recently been looking at the bacteria that live in the thick fleshy gills of mussels.

NICOLE DUBILIER: The mussels are pretty amazing because they're incredibly flexible. What they seem to be doing is depending on which energy source is present in their environment, they hook up with the bacteria that can provide them with energy.

MARC SANCHEZ: For mussels at hydrothermal vents, that means bacteria with energy from hydrogen sulfide or methane. Nicole looked at those same types of mussels in a different part of the sea where oil and tar seep up from the ocean floor.

NICOLE DUBILIER: And the big surprise for us was that the mussels there have formed a symbiosis with bacteria that can use compounds of the oil as energy sources.

MARC SANCHEZ: OK, you know how giant pandas are totally crazy for bamboo? It's like all they eat. Well, imagine we just figured out that giant pandas eat tires too. That's what Nicole is finding out about these mussels she's studying. And if you think about all we don't know about life in the deep sea, Nicole's findings could be the beginnings of something huge.

NICOLE DUBILIER: There's so much we have to still discover in the deep sea. And it is so biologically rich and diverse, and has so many more different types of environments than outer space that certainly if we want to learn more about life, and how life evolved, then the deep sea is the place to go.

MARC SANCHEZ: Nicole Dubilier, I couldn't have said it better myself. Some of you astute listeners might remember that we talked about hydrothermal vents in our episode, "Why Is The Ocean Salty"? You can go explore that episode on our website And while you're there, why not just follow Nicole's lead and vote for team deep sea?

MOLLY BLOOM: Good stuff there. Sanden.

SANDEN TOTTEN: All right. Let me tell you a story about massive rockets, floating bases in space, and the first humans on Mars. Sounds like science fiction, right? But within your lifetime, Harper, this could become science fact. You or someone you know could be the first person to walk on Mars. Remember Nujoud Merancy from early in the show? She's the spaceship expert from NASA. She's now working on a spaceship called Orion. And it'll launch on top of the Space Launch System, which will be the most powerful one that NASA's ever built.

NUJOUD MERANCY: So the big rocket gets us away from the Earth, and then Orion can actually keep four crew members safe and sound for up to 21 days all by itself.

SANDEN TOTTEN: And these two are designed to take humans past low Earth orbit into parts of space we haven't reached since the days of the moon landings back in the 1970s. But this isn't just a mission to do some epic sightseeing from way up there. The Space Launch System is what's called a heavy lift rocket because, well, it can lift a lot of heavy things obviously. One of its main goals is to help build a, wait for it, a base in space. NASA hopes to use this base to help us go to Mars.

NUJOUD MERANCY: It's going to take a lot of stuff to go to Mars. So when we go to Mars, it's going to be a two-year mission. So you need a big habitat, you need all the food for the crew, you need all the resources, you need all the spare parts in case something breaks. You need all of that on your spaceship before you go because it takes nine months just to get to Mars. And then you're there for six months. And then it takes nine months to come home again. So two years of stuff has to go to Mars.

SANDEN TOTTEN: But here's the thing. If you wanted to send up two years worth of supplies and gear in one trip, you'd need a rocket so big that it'd basically be too heavy to launch.

NUJOUD MERANCY: Yeah, I mean, the scale of the rocket you would need to send that up on one trip would be astronomical.

SANDEN TOTTEN: Nice space joke there, Nujoud. So NASA is taking it one step at a time. The Space Launch System will send stuff up piece by piece. Once the stuff's up in space, it's weightless. So getting it to Mars will be a lot easier. In fact, you could send up pieces for a Mars spaceship and build it in space so you have a second feel for long distance travel. It doesn't have to also escape Earth's gravity first. Clever plan, right? So Nujoud says the current goal is to build this space base, and then start working on the rest of the pieces for the first crewed mission to Mars.

NUJOUD MERANCY: We can start putting it together around the moon and use that as sort of a deep space gateway, a launching pad, onto bigger missions. Orion will fly in two years for the first uncrewed flight. And then a few years later, we'll do the first crewed flight. And we'll start sending elements to the moon in the 2020s. So hopefully, we've built up this Mars vehicle by the mid 2030s to actually start sending people to Mars. These programs take years to put together.

So the kids growing up today, and their interest in science, I need them to go get their schooling, and get degrees. Because we need to hand this off to them to keep it going. So I hope these kids get really interested.

SANDEN TOTTEN: So that's where it comes back to you, Harper, and you listeners at home. Space is great, but it takes a lot of people. And it takes decades to explore. And that means that even by the time you're out of school well on your way to being a scientist yourself, there will still be plenty to discover. And in fact, you could be part of that first crew to Mars. So pick team space. Because one day, you could be the one exploring it, or sharing your findings with the rest of the world, or just finding out about cool stuff that your friends have done when they went up into space.


MOLLY BLOOM: Thank you, Sanden. OK, Harper, and listeners at home, I want you to think about those two final rounds. Think which is cooler, deep sea or outer space. All right. And now, it's time for closing statements. These are very short. Your last chance, Marc and Sanden, to win over Harper and all of our listeners.

MARC SANCHEZ: All right. I've got one word for deep sea, life. Cephalopods, sharks, bioluminescent jellyfish, not to mention all those microbes down there that are waiting to be discovered. The ocean is full of life. Space, it's out there. But the deep sea is here. We can touch it. It's a dream that we can live. So dive in and vote for team deep sea.

MOLLY BLOOM: Thank you, Marc. Sanden.

SANDEN TOTTEN: OK, so a lot of people think space is just distant and frivolous. But the thing about it that's really amazing is that it helps explain where we came from. And I don't just mean like us, people. I mean, like everything. By understanding things like the big bang and the expanding universe, we're really learning about how everything came to be and the story of our existence as a species, as a planet, as a universe.

And that's pretty cool. And we talk about Earth, and we talk about deep sea as if it's different from space, as if it's a separate thing. But in reality, everything on this planet, this planet included, all came from space at some point. It's thanks to space that we had suns burning up, exploding, and shooting out all sorts of elements that later recombined and formed things like planets, and minerals, and elements that eventually became life here on Earth.

So in a way, space is all of us. It is the deep sea and it is the great beyond. And to understand all those things, and how they all work together, and the universal rules controlling everything, we really need to look out into space and study it, and learn about crazy things happening and interesting things happening so that we can understand where we come from and the stuff happening here on our planet even better.

MOLLY BLOOM: Two excellent rousing closing statements. Harper, please award one final point to whichever closing statement you found most compelling. And now take a look at your score sheet, Harper.

SANDEN TOTTEN: Oh, I'm so nervous.

MOLLY BLOOM: Count up the points. And tell us, who won the debate? Deep sea? Or outer space?

HARPER: Outer space.



MARC SANCHEZ: Well, congratulations.

SANDEN TOTTEN: Yeah, doing my dance. Being real happy.


I haven't won in so long. Thank you, Harper.

MOLLY BLOOM: This is a well--

SANDEN TOTTEN: I'd like to thank Galileo, I'd like to thank Edwin Hubble, I'd like to think Einstein for his theory of relativity.

MOLLY BLOOM: This was a very well-fought debate. Good work to both of you. And thank you, Harper, for being our fair and impartial judge.

SANDEN TOTTEN: Thanks a lot. Hey, Marc, put her there. Great-- you did great arguing.

MARC SANCHEZ: You too, sir. Until we meet again.


MOLLY BLOOM: And we would love to hear if our listeners agree with Harper's decision. You can head to our website to vote in our poll. Who won the debate, deep sea or outer space? Share your opinion at for our last debate, lasers versus fire. Fire one on the show. But lasers one online. So we'll see what happens this time.

Now before we go it's time to read the most recent group of names to be added to the brain's honor roll.


SUBJECT: Brains honor roll. High five.

MOLLY BLOOM: That's it for this episode of Brains On!

HARPER: Brains On! is produced by Marc Sanchez, Sanden Totten, and Molly Bloom.

MOLLY BLOOM: Brains On! is made possible in part by a grant from the National Science Foundation.

SANDEN TOTTEN: We had engineering help this week from Jon McMullen, Corey Sharapova, Veronica Rodriguez, and Dan Kearns.

MARC SANCHEZ: And production help from Lauren Dee and John Lambert.

MOLLY BLOOM: Special thanks to Leslie Price, Jim Gould, Carroll Graves-Gould, Tom Crann, Lynne Warfel, Eric Wrangham, Hans Buetow, John Moe, Tracy Mumford, and Max Nesterak.

HARPER: Looking for ways to keep the fun going after this episode? Sign up for our newsletter.

MOLLY BLOOM: It features cool experiments, fun videos, and so many ways to show off to your parents just how smart you are. You can also find links to our book giveaway and how to submit questions and recordings to us. Sign up at

HARPER: Don't forget to send them as animal farts.

MOLLY BLOOM: Can you get smells over email? I hope not.

HARPER: You can check out all things Brains On! at our website,

MOLLY BLOOM: We're on Instagram and Twitter @brains_on. And you can search for us on Facebook and Pinterest too.

HARPER: Thanks for listening.

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