What are extremophiles?

0:46 Welcome to Science Is Not Boring by kidopoly.com. I'm Mira! And I'm Finn! Before we blast off, we have a massive shout-out to brothers Aidan, who is nine, and Dallan, who is six, in Rollsville, North Carolina.

1:02 And a huge shout out to five-year-old Laclan in Nova Scotia, Canada.

1:07 Aidan, Dallan and Laclan all ask for an episode about aliens and where life comes from. Great pics! This one is for all of you.

1:17 If you haven't already, tap follow wherever you're listening so you never miss an episode.

1:22 So today we're asking the biggest question ever. Could life exist in the universe that is completely different from us?

1:30 Wait, you mean like real aliens? Not just in movies.

1:35 Exactly! Our Milky Way galaxy has hundreds of billions of stars, and there are trillions of galaxies out there. There has to be life somewhere. But what are we looking for?

1:47 An alien made of jelly that eats rocks?

1:51 Maybe. To find them, we have to look in the most extreme places. Did you know there is a lake in our solar system bigger than all the great lakes combined? But it's filled with liquid methane at minus 179 degrees Celsius. No way! You turn into a popsicle instantly! You would, but some scientists think bizarre creatures could be swimming in it right now.

2:17 To understand alien life, we first have to look at life on Earth. Every living thing we know of, from a tiny ant to a giant blue whale, depends on three main things.

2:31 Let me guess. Water, oxygen, and snacks?

2:36 Close. Liquid water, a chemical element called carbon, and DNA, which is like the instruction manual inside your cells. Why does everything need water and carbon? Well, water is the perfect liquid to dissolve nutrients and move them around a living body. Without it, the chemical reactions that make life happen would just freeze or dry up.

3:01 Oh, so blood is mostly water, and sap in trees is mostly water.

3:05 Exactly. And carbon is like nature's ultimate Lego block. It can connect to other elements in four different directions at once to build really complicated shapes. So it's the perfect building block for making life. Yes. For decades, scientists thought that if a planet didn't have liquid water and carbon, it would just be a dead, empty rock.

3:30 But they were wrong, weren't they? They were so wrong! They eventually discovered creatures called extremophiles. Living things that survive in places where life should be totally impossible. Where exactly did they find these extremophiles? In space. The first massive discovery was right here on Earth, in 1977.

3:51 Scientists took a tiny, deep-sea submersible named Alvin down to the bottom of the Pacific Ocean. How deep did they go? How big was the submarine? Alvin was a tiny titanium sphere, barely big enough for three people. They dove to a place called the Galapagos Rift, about 2,500 metres deep. That's like stacking seven Empire State buildings straight down.

4:18 It must have been pitch black down there. Sunlight can't reach that deep. It was completely dark and freezing cold. The scientists didn't even bring a biologist with them because they expected to just map empty, dead, volcanic rocks.

4:34 What happened next? Did they crash into something?

4:37 No, they saw shimmering water. They found underwater volcanoes called hydrothermal vents shooting out black, superheated water. The water coming out of those chimneys was 350 degrees Celsius.

4:53 Wait, 350 degrees? That's hotter than an oven. Wouldn't the water instantly boil into steam?

5:01 Normally, yes, but the massive weight of all that ocean water above them creates so much pressure that it physically stops the water from boiling. But the craziest part wasn't the heat, it was the life. Life?

5:16 In boiling toxic water in pitch darkness.

5:20 Yes, they saw giant tube worms up to eight feet long with bright red plumes waving in the currents, and swarms of pale isla shrimp and strange white crabs.

5:32 But if there's no sunlight, how do they get energy? Plants need the sun to grow, right?

5:38 Exactly. These extremophiles use a wild process called chemosynthesis. Bacteria inside the tubeworms literally eat the toxic hydrogen sulfide spewing from the vents and turn it into energy.

5:54 Whoa! So they eat toxic chemicals instead of sunlight? That's basically alien life right here on Earth.

6:01 It totally is! And if life can survive on toxic chemicals at the bottom of the ocean, astrobiologists realized it might survive in even weirder environments in space.

6:14 Like where? On Mars.

6:17 Mars is a great target, but let's go a billion miles away from the Sun, to Saturn's largest moon, Titan. In 2004, NASA's Cassini spacecraft arrived to study it. A billion miles? How long did that take? It took Cassini seven whole years flying through space just to get there. When it arrived, it found Titan wrapped in a thick, dense, golden haze of nitrogen gas.

6:46 Did it have special cameras to see through the clouds?

6:49 Yes. Cassini bounced its special radar through those thick clouds, and it saw an incredibly Earth-like landscape, with coastlines, rivers, and giant lakes.

7:02 Lakes?

7:03 You mean there's liquid water on Titan? Not water. The surface of Titan is minus 179 degrees Celsius. That's minus 290 degrees Fahrenheit. At that temperature, water is frozen harder than granite. Then what's filling up those lakes? Liquid methane and ethane. On Earth, methane is a gas we use for fuel.

7:27 But on Titan, it's so incredibly cold that the methane gas turns into a liquid. It actually rains liquid methane from the sky, carving rivers into the mountains. How big are these lakes? Cassini measured the depth at the largest sea, called Kraken Mare. They found it is about 300 meters or 1,000 feet deep and covers an area larger than all five of our great lakes combined.

7:55 A thousand-foot deep sea of liquid fuel?

7:58 Could there be methane monsters swimming in there?

8:02 Scientists have actually run complex computer models. They think a weird, methane-breathing cell could potentially exist. It wouldn't use water at all, and its cell walls would be completely different from ours. But what about the carbon part? If they don't have water, do they still have carbon? Maybe.

8:22 But some scientists think alien life could be built out of a completely different element, like silicon. Silicon?

8:30 Like the stuff we use to make computer chips.

8:32 Yes. On the periodic table of elements, silicon sits right below carbon. It can also form four chemical bonds at once, making it another perfect Lego block for building complex alien molecules.

8:47 Wow, silicon-based aliens? Are we looking for them right now?

8:51 We're looking everywhere. The James Webb Space Telescope, which is the most powerful telescope ever built, is currently scanning exoplanets looking for weird chemical biosignatures.

9:04 What's an exoplanet? And have they found anything yet?

9:07 An exoplanet is a planet orbiting another star. Recently, they pointed the telescope at a super-Earth planet called K218B. It orbits a red dwarf star about 124 light years away.

9:23 124 light years? That is so incredibly far.

9:27 What did the telescope see? By looking at the starlight passing through the planet's atmosphere, they found lots of methane and carbon dioxide. But they also spotted a faint chemical fingerprint of a gas called dimethyl sulfide, or DMS for short. What's so special about DMS? This is the mind-blowing part.

9:48 On Earth, DMS is only produced by living things. Specifically, it's made by marine phytoplankton, which are tiny microscopic ocean algae.

10:00 Wait, are you saying they found space algae on an alien planet?

10:04 Haha, we don't know for sure yet. The signal is weak, and scientists need to do more follow-up observations to confirm it. But finding that exact chemical means our search for weird, wonderful life in the universe is finally getting real.

10:20 That is the coolest thing I've ever heard. I want to be an astrobiologist. Alright, Finn, time for the quiz.

10:27 Are you ready? Okay, I'm ready. First question. In what year did scientists first discover the weird deep sea life at the Galapagos Rift? Next one. What is the name of the deep sea submersible that made that discovery? Question three. What is the name of Saturn's largest moon where it rains liquid methane?

11:01 Here's number four. How cold is the surface of Titan in degrees Celsius? Last question. What kind of chemical gas did the James Webb Space Telescope spot on exoplanet K2-18B? Great job! Let's see how you did. The first answer is it was 1977. For question 2, the submersible was named Alvin. Number 3. The answer is it's Saturn's moon Titan.

11:40 Question 4. It is a freezing minus 179 degrees Celsius. And the final answer is, it spotted dimethyl sulfide, or DMS. That was so mind-blowing! I'm just glad our lakes are made of water and not freezing liquid methane.

11:59 Haha, yeah, me too. If you guys liked learning about giant tube worms and weird alien planets, please leave us a five-star review.

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12:27 And if you want a shout out on the show or just want to say hi, email us at hello at kidopoly.com.

12:34 See you next time on Science Is Not Boring. Bye everyone!