StarTalk Podcast
Hosted by Neil deGrasse Tyson
Take a tour of the solar system with Mars Exploration Rover scientist Steve Squyres and planetary scientist Heidi Hammel.
8,884 words · 5 speakers
Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.
Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now.
Welcome back to StarTalk Radio. I'm Neil deGrasse Tyson. I'm an astrophysicist and director of New York City's Hayden Planetarium. And joining me this week as my guest co-host, Chuck Nice. Chuck.
Thanks for having me back Neil.
I will not soon forget the Super Bowl show, the football show. You were on fire.
Dude, that was great fun.
You were out of control.
That was great fun, man. Ready to get back into it today and get high on science.
We're gonna get really high on science. Today's show is a tour of the solar system.
Sweet.
A tour of the solar system. I think every now and then you gotta take a tour of your backyard.
Fantastic.
That's what you gotta do.
Will you be our tour guide?
I will be your tour guide, but I have some help from two very competent colleagues of mine. One of them, Steve Squyres. He's the scientist behind the Mars Rovers.
Wow.
You know, we all read about the rovers and he saw pictures of the terrain. He's in charge.
And?
These are his babies.
Did they blame him when they broke down?
No, they blame him when they save. You know, these things should have broken down long ago.
Oh, really?
Way long ago. So he's been saving them. He's their savior, as it were.
We're also will be hearing from Heidi Hammel. She's a senior research scientist at the Space Sciences Institute in Boulder, Colorado. Colorado, yeah, yeah. So that should be fun. But you know, you know who's a friend of StarTalk Radio?
Ah, I do know. Bill Nye, the science guy.
So are you, were you influenced by him when you were a kid?
Absolutely, absolutely. And by kid, if you mean 20, yes.
So I got ahold of Bill Nye. By the way, lately, he's the executive director of the Planetary Society. He finally has like a real job, you know?
Gets a paycheck and everything.
Honestly, I always wonder, what else does he do?
What does he do?
Except show up on TV and talk to kids.
Exactly. No, no, he's actually talking to grownups now, including Congress.
Okay.
So he's gonna start us off and give us, put us in a good way, getting us to think about where we are in the solar system and where we might one day go.
The most recognizable image to anyone on Earth is the Earth as seen from space. When you look above you at night these days, I hope you notice occasional very bright objects among the stars, other planets. Humans have spent centuries trying to know all about them. By exploring the solar system, first with our eyes, then telescopes, and these days with extraordinary spacecraft, we have come to know that Mars is cold, Venus is hellishly hot, Saturn would float if it could, and our Earth is but one world among thousands of objects whirling about a common star. Between and beyond the planets are all manner of objects: comets, moons, asteroids, distant icy plutoids, and dust. Often as a young scientist, I'd be given a textbook with a place to write my name inside
the cover, below that, my street, my city and state. But I'd go on: United States, North American continent, Earth, and Sun. Because we've explored our solar system, I could have added the third rocky ball from the medium-sized star. Have a look around. Your life is changed every day by explorers who've pondered our place in space. For StarTalk Radio, I'm Bill Nye the Science Guy.
That's my boy, Bill Nye.
Nice. Okay, I just gotta ask you, man.
What's that?
Plutoids?
Plutoids.
Is that like a cosmic mint?
A plutoid?
What a, that's a great, great product name there, right there.
That would be.
We should start that out. But what would your breath smell like? That's the question.
Hopefully not cosmic dust.
It's cosmic, yeah, you know, gotta watch out what stuff smells like out there.
So the solar system, its formation was four and a half billion years ago from a huge giant gas cloud, and right in the middle of that gas cloud, where it's densest and hottest, that's where you get the Sun. And that's what forms first, and then you get planets and other stuff forming around it. There was a day when if you learned about the solar system, it would be like an enumeration of the planets one after another. But, excuse me, the solar system is so much more than that. From the moons around planets to the dust in the plane of the solar system, to asteroids, some of which hit the Earth, comets. It's a very rich, dynamic place. And in case you really want to geek out on the Sun, the Sun has an actual official classification code.
It's a G, capital letter G. Arabic numeral two.
Roman numeral five.
So G two five.
Yes.
In three different, uh, languages and letters and alphabets and number systems.
Each one means something different.
If you want to geek out on the sun, that's what it would, that's what it is.
Now, why G two five? Cause that really, I don't get it.
Okay, so G.
G two five.
G tells you what the temperature is, okay?
Which is a gazillion degrees.
That's what G stands for.
Really, that's it?
For a moment, I almost felt smart. I was like, I got it right.
So, the stars in order of decreasing, uh, temperatures, O B A F G K M. So, the sun is one of the cooler of the stars.
Oh, yeah. You know it is, baby, because it's here in our solar system.
It's cool, but it's actually white hot. And the sun is often portrayed as yellow, but it's actually white. Just go outside and look. It's white. In broad daylight, it's white.
Right.
What happens when it gets low on the horizon? Then you can look at it without burning out your eyes. Hey, look, the sun is yellow orange. Cause the atmosphere just changed its color.
So those are particles in our atmosphere that actually change the color.
That actually, what the particles do is scatter the blue light out of the rainbow, leaving behind the red and the orange.
So basically, if you were in space, you would look at the sun.
And be white no matter what angle.
And be white no matter what.
No matter how you put your head.
Burn your eyes out and that'd be the end of it.
That'd be the end. The last experiment you did. So what I've got is, let's go to my, let's go to my colleagues. Uh, they've visited me in New York, in my office. Steve Squyres, Principal Investigator of the Mars Rovers, Professor of Astronomy at Cornell University, and Heidi Hammel, who is, who is total planet babe. This is, she's all about planets. And so, let's find out what we all have to talk about.
So Steve, I keep thinking of you as like Mr. Mars. Anytime I look up in the sky and Mars is there, I'm thinking of your two rovers there. When you look up at Mars in the night sky, is that what, do you think that too?
You know, Mars.
Would you just wish you were there?
Mars looks different to me than it used to. It used to be, I I can remember before we launched them, looking at Mars in the night sky and it just looked impossibly far away.
So now it's your backyard.
And I look at it now and I think I know this place.
You're a kid playing in your backyard.
It's a sandbox.
Yeah. It just, it feels totally different to to look at Mars now than it did a long time ago, yeah.
Do you see it, though, do you, when you see it in the sky, do the pictures from the rovers, is that what you see?
Ah, kind of, except I don't think in terms of pictures. I I sort of feel like I know what would it, what it would be like to be there. You know, not just the pictures of the surface, but I know what the clouds in the sky look like. I know the seasons.
The rovers are his avatar.
It's kind of feels like that, yeah, it does. And I I, we've experienced Mars through those rovers for so long. I I kind of feel like I know what the place is like now.
Yeah, but are you now sort of, do you have Mars on the brain so that you, it's hard to think about the rest of the solar system?
No.
Heidi, Heidi, you get around the solar system, right?
I sure do, yeah, I look at a lot of other planets besides just Mars.
So you're not just-
We don't have that, we don't have those images, we don't have those rovers on the surface, so I still think a lot in pictures.
Plus, half your planets don't have surfaces.
Well, that's true, yeah, they've got, but they've got-
I have to ask, what's your favorite?
You know, it changes with time.
Ah, it's just like picking your children, right?
Yeah, exactly, I don't, I don't play favorites.
Uh huh.
You know, at different times, different planets do different things.
Mm-hmm.
And so if you were looking at, you know, Uranus at equinox and it's busted out with clouds-
And that's the official, it's not Uranus, right, it's Uranus.
Yeah, you know, I kind of gave up on that whole thing.
I gave up on that.
You were sure-
For a while, I was on a mission to educate people about Uranus. And then my own hometown paper wrote a story about those yellow lights, you know, that they were trying for, to cost efficiency. And the headline-
Oh, for the nighttime, for the streetlights?
Yeah, yeah, yeah, for the streetlights, right, streetlights at the night, so that it would be darker, um, less light pollution. And and some people didn't like it, and they ran a headline about the Uranus-colored lights. And that's when I gave up. Yeah, I would call it Uranus, um, that's more traditional. But, you know, when Voyager flew by Uranus in 1986, it was dead. There was like maybe ten clouds, if you really stretched the contrast of the atmosphere.
So Uranus was a big ball of gas with no surface features.
Basically, yeah, I mean, that's right. If you and I were on a spaceship outside it- When Voyager flew by, when Voyager flew by, it didn't see anything. And so everyone thought it's dull and boring. Well, that's not what it's like right now. It's in a completely different season. And the atmosphere is turning on, and there's bright clouds, and there's dark spots, and there's all kinds of activity on this planet. And this is my favorite right now, because flies in the face of what we were taught in school about Uranus, you know, we were taught that...
I remember the books. It's, it, it, Uranus was an example of a boring...
It's the boring one, yeah.
Well, that's right, which is just absolutely not true right now. And the books are starting to finally catch up with reality.
Now, Mars, of course, is a dynamic place.
Yeah, it's changing all the time. I mean, it's got seasons, very much like the Earth does, uh, very different at different times of year, it's...
It's not only very much like, it's like, almost exactly like the Earth does, right?
Yeah, yeah.
I mean, it's tipped how many?
Twenty-five degrees.
Twenty-five, and we're twenty-three.
Twenty-three and a half, yeah. So it's, it's almost the same, the year is longer, of course.
Rotates once in how many?
Twenty-four hours and thirty-nine minutes. And let me tell you, if you're operating rovers on Mars, that just plays havoc with your life.
Okay, next time that happens to me, I'll keep that in mind.
Uh, you know, you would think it'd be...
Listeners, when you're operating rovers, just, just get, get ready for this.
You know, you would think it'd be nice to be able to sleep in an extra thirty-nine minutes each day, but it, it, it kind of adds up in weird ways.
It gets out of sync, doesn't it?
It gets out of sync.
Well, you think it's like a, in, a slow jet lag that eats away at you.
We lived on Mars time for months. We had Mars alarm clocks, Mars stopwatches. Uh, we had food service on Mars time, maid service in our apartment on Mars time. We had blackout curtains on the windows, so you couldn't tell if it was daytime or nighttime.
But did you adjust, or did you adjust to it, or did you really feel human and terrestrial?
We...
Because your bodies couldn't adjust to it.
Our bodies could adjust to it just fine as long as Earth did not interfere in our lives.
In other words, the blinds on the windows were absolutely...
That was fine, and if you have to live a day that's twenty-four, thirty-nine, it's perfectly easy to lead unless you have to interact with real human beings in the real world on Earth.
You were basic... Like a spouse, or you walk your dog or something, that sort of thing. So what you're saying is you were basically in a Mars habitat here on Earth?
Yeah, we kind, we kind of were, but then there would be events, you know, somebody would decide there had to be a meeting at eight o'clock in the morning, Pacific time. And if it's in the middle of my night, I would still expect it to show up. And that was when it got difficult.
Wait, I thought you were in charge.
Not when it came to interacting with the press. When we had press conferences, they were at 8 a.m. Pacific and that was it. And, uh, yeah, that telling CNN that we want to have our press conference at 3 a.m. just didn't work real well.
So the press likes your rovers?
I think they do.
Geekin' out on the planets.
Dude, that was like Geek-a-palooza.
Geek-a-palooza. Isn't it great? Everybody has a favorite planet? How many people in the street, you know, just, well, that's my favorite planet for these 11 reasons?
Yeah, well, most people you ask, what's your favorite planet? They're gonna be like, the one I'm standing on.
Not the one, well, this one used to have no surface features and then cloud layer. There's a whole analysis of what they follow and why and it keeps them pumped every single day.
Yeah, I'm just, I'm just glad to know that Mars has seasons.
Yes, yes, and polar ice caps. This, this accounts for its allure in the history of science fiction writing. Why people have chosen Mars as a target for life, more so than other planets.
Oh darling, I can't wait until we take spring in Mars.
Not only that, what, what we have on Mars is not only the rovers, they're orbiters as well. So that we can know where we might send the rovers next. Otherwise, you're kind of driving blind. And what's good about rovers is it's a mobile geologist and you don't have to go there. Plus, the rover doesn't have to come back. So if you send a human being, they probably, they usually want to come back.
Normally.
You gotta feed them, you know?
You gotta send a misanthrope. I hate you guys.
Yeah, yeah, get, get out of here, go to Mars. So one of the things we found recently in Mars is methane emanating from the sides of ravines in Mars.
Really?
Yeah, and methane is the kind of gas that is produced within the anaerobic digestion of food.
Okay, so actually Mars is a big giant fart, is what you're saying?
Did I say, did I?
I did.
Chuck, that's why we have you on the show.
That actually sounds more like Uranus. Or should I say Uranus?
No, Uranus, yes, we just got schooled on that one.
Uranus, that's what it, Uranus.
So, uh, after the break, we'll talk about the search for life and how the search for water is driving the search for life. Cause everywhere on Earth where you find liquid water, you find life. Any place, including places like the Dead Sea. The reason why they call it the Dead Sea? They didn't have a microscope to tell what would do the backstroke in the-
But there are, there are things alive in the Dead Sea.
Not fishes, but there's other stuff that's alive for sure.
We've gotta take a quick break, but more StarTalk when we return.
Welcome back to StarTalk Radio. I'm Neil deGrasse Tyson with Chuck Nice, comedian and TV host and all-around good funny guy. And I got him here just to, just to chew the fat.
And I appreciate it.
Well, it's, it is a pleasure and an honor to have you onboard.
Thank you, sir.
And we're talking about the solar system today, a tour of the solar system, basically. We have two of the world's experts to serve that up. One is Steve Squyres, who runs the Mars Rovers, which we've all heard about. Everyone's heard about the rovers, even if you didn't know he was the man in charge. And there's a whole team, of course, but he's the, he's, he's the main-
He's the top banana.
The top banana.
There you go.
And Heidi Hammel, who's an all-around planet geek-ress. I mean, is that the word?
Geek-ress, that like, you just made it up. I like it.
We make it right on the spot.
That's how we roll.
And so the solar system is full of a lot of sort of alien worlds. There are moons and planets and comets and asteroids and, and one planet is different from the next. One moon is different from the next.
These are, these are exotic places.
Is any place you, one of these you might want to visit one day?
Pandora. I just love those blue people. They're so adorable with their little tails and I love them.
And they're, and they're so, they're so nimble on tree limbs.
Exactly.
You worry about me sometimes, Chuck. You know, because there's so much going on in the solar system, not everything has a perfectly circular orbit around the sun. A circular orbit is the only orbit you can have and not hit something else. Okay?
If you do not have a circular orbit, there's a chance you're gonna get hit, you're gonna hit something, something's gonna hit you.
Now, from what I understand, aren't there planets here in our solar system that have an elliptical orbit?
Yes, it, uh, no, not anymore.
Pluto, don't get me started on Pluto, cause we'll take it outside.
Let's go, let's go back to Steve Squyres and Heidi Hammel. They're gonna tell us how, what kind of a shooting gallery the solar system actually is. Now Heidi, you go way back with the press. My first encounters with you, as I think with many, were with the comet impact on Jupiter. You were like the face of the comet.
The first, the first impact on Jupiter.
Yeah, there's more than one?
We just had another one in July.
Oh, I know about that. I forgot all about that. I just, I've been busy. I'm sorry. I'm sorry, okay?
It's an impact. It's, you know, it's the size of the Earth kinda thing. Big explosion.
So Jupiter's kinda asking for it, right?
Yeah, well, yeah.
Well, it's a big target.
Well, it's there to take one on the chin for us, you know?
It's a big target.
That's really true. Really true. It's protecting us.
It's protecting us.
It's our big brother protecting us.
Yeah. But yeah, my first interactions with the press on any large scale were back in 94 when we were doing weather broadcasting from Jupiter.
What, so the, what, what was going on every day on Jupiter?
Absolutely. It was pretty exciting stuff.
Yeah. So if that happens just in the last couple of decades, this must be going on all the time, right?
I would think so.
Living in some special time when Jupiter's getting hit.
We thought we might have been lucky the first time. And when it happened just exactly 15 years later, we realized, hmm, maybe we aren't so lucky.
All right. Now, here's a question. Now that you know what to look for, now that you know what an impact on Jupiter looks like, is there data mining you can do? Can you go back to old pictures?
Data mining. So it's like looking back in an old, yeah.
Even after the 94 impact, some folks went and did do that. They went back and looked. We had the planetary patrol telescopes. I don't know if you're aware of that. Network of 24-inch telescopes that were just studying Jupiter. You know?
Creating an archive of data.
Exactly. And there's nothing like Shoemaker-Levy 9. You know, the big one in 94 was there.
So you would've seen it. The pictures are good enough that you'd know.
Absolutely. That's right. And people, you know, do talk about the historical record. There's reports of Cassini himself, not Cassini the spacecraft, but Mr. Cassini.
Cassini the guy.
Cassini the guy, who did these drawings.
It's weird to think there are people with names after spacecraft. What a coincidence.
When you said Galileo, you know, we're talking about Galilei, the guy, or Galileo, the spacecraft. Cassini drew pictures of.
Or the European Navigation System, Galileo.
That's right.
Their counterpart to our GPS.
You gotta get some more astronomers' names in play, like, you know, Neil deGrasse Tyson.
Yeah, named, mission named after you.
You have to die.
Yeah, yeah. That's right, these are named after dead people, yes, okay.
But people did go back and look, and they haven't seen conclusive evidence in the past of any big events like this. But I'll tell you, nowadays, these amateurs have terrific telescopes, they have amazing CCD systems.
Allow me to clarify, in most professions, if you accuse them of being an amateur, it would be an insult. Whereas in astronomy, amateur is a badge of pride and courage.
Well, and also, they do terrific science now. There's synergy between the professional astronomy community that basically has the really huge telescopes, and the amateurs who have smaller telescopes, but they're terrific, and they have tons of time, because the amateur just goes out at night and spends all night looking, whereas.
And they're in every time zone.
Every time zone, all around the world. With these big telescopes like Hubble or the Keck ten-meter, you might get half an hour a year. And that's all the time you have to look at your objects. So they rely on the amateur community to feed us information about things like impacts on Jupiter. It was an amateur who spotted that and alerted the professional community.
This later, the second impact, yeah.
The second one, that's right.
So I'm sitting between two very different kinds of scientists now. One who, you, Heidi, who are still using telescopes.
She's kind of behind the times.
No, I'm looking at things that are far away.
And Steve, you're just there, you know? You don't worry about the optics, you don't worry about bad weather.
Oh, we worry about both of those, my friend. First of all, we got optics all over these rovers. Second, we are very, very sensitive to the weather on Mars.
But it is true that he can send spacecraft to his object and get them there within, you know, a reasonable funding cycle.
Before he dies.
Yeah.
If we want to start talking about planets around other stars.
We are gonna be sending spacecraft.
Or even, even some of the, uh, you know, some of the, the planets in the outer solar system, if you're talking about a Neptune, uh, a mission to Neptune, the time scales for pulling that off are very long.
Well, so that's why the Pluto mission, the New Horizons, that's on, there was like a light payload with some really huge engines.
To get it there.
That's right, yeah.
Yeah, yeah, that one was, that, that was booking.
And it's still on its way and we got years to go.
Yeah. Another five, yeah. So it's, it's humans attack the solar system. That's what this is about, Jack.
That's, I've learned some things, man.
Well, this is what we're, this is at the point of the show.
The, the thing I learned, uh, that most stuck out was that in astronomy, size matters.
Yes, it does.
Everybody has telescope envy.
Yeah, so, whatever size is your, in fact, you go to astronomy conventions, how big is yours?
You know? It's true, but here's the problem, at some point you gotta carry the thing to the observing site and above a certain size, you just can't carry it.
You can't do it.
Yeah, you can't even do it, so it's.
Yeah, I know what you mean.
There's more, it's not. Chuck. Chuck out of control.
Okay, let me shut up.
So what we have, so what we have going on in the solar system is that planets are no longer just dots of light with pretty atmospheric conditions that photographed through a telescope, we can actually go there and look at surface features. And so there's a whole frontier of planetary science called comparative planetology. And if there's a mountain on one planet, look for a mountain on the other, there's craters, valleys, uh, riverbeds, you compare one object to another. And, and especially for the terrestrial planets, Mercury, Venus, Earth and Mars, they're small, they're rocky.
And so we can learn about one by studying another. For example, so we can ask, well, while we've been going to Mars for the past thirty years, guess where the Soviet Union back in the old days, well, guess where they went the most?
Venus.
Yes, and they had a whole series of Venera. Venera spacecraft.
Venera spacecraft.
That's what they're called. That's right, Venera. So that's the genitive.
Kinda sounds like a medical condition. That's all I'm saying.
I'm just saying, well, well, it's funny that you should ask. Because in-
Man, I got a bad case of Venera, man.
That's what I'm, let me tell you.
Go ahead.
So, what happened was astronomers, when we figured, you try to come up with words of, for names for where you come, if you're from Earth, Earthling.
If you're from Jupiter, you're Jovian. If you're-
I did not know that.
You didn't know that? You didn't buy Joe.
No, well, you were, buy Jove comes from-
Jupiter, of course. Of course, yes. And so, and Venus would be Venusian.
Venusian.
If you're, if you're come from Venus, you're Venusian. And so, the reason why we came up with Venusian is because the proper genitive form of Venus-
Is venereal. And the medical doctors got to that word before we did.
I am so pissed off.
That is so cool.
I am so angry about that. And now, they took the word right out-
Right out from under you guys.
And, and so they, and, and why name it after Venus? Because it's the diseases common to love and beauty and all that go with it.
That makes sense.
Venus, the goddess of love and beauty.
Oh my God. I'm just happy to know that, you know, this little condition I have that it needs antibiotics is so romantic.
TMI right there. TMI. So-
Oh, it'll clear up. Don't worry.
Now, here's the problem on Venus. Yeah, if we sent you to Venus, it would all be cleared up. Because it's 900 degrees Fahrenheit there.
Oh, sweet.
There's a runaway greenhouse effect going on there. And that's, makes it very hard to investigate because your metals melt, it'll melt lead, for example. You can't have lead- Lead solder or anything.
Only Superman could do that. So that's hot.
Is that right?
Yeah, his laser vision.
Okay, you know, we should do it-
Which is, what's funny, he couldn't see through lead, but yet he could melt it with his heat vision.
Interesting.
How crazy is that?
That's crazy. You know, we're gonna do a special show on the physics of superheroes.
Get out.
Should we invite, should I get you back for that?
Aw, man, if you don't, I will never speak to you again.
All right. That's not, we'll work that one out. And so of these destinations Pluto is on our targets. The ex-planet Pluto. It's got what's called the New Horizons mission. It's booking. It's the fastest hunk of hardware we have ever sent anywhere. It's on its way to Pluto right now. Get there in 2015. And that's, we're headed there. And so.
That's one hell of a road trip, man.
It's one hell of a road trip. And it's on hugely powerful rockets because the principal investigator of that mission wants to make sure you get to Pluto before he dies. See, that's how that works. This is the number one rule.
It's like a trip to my mother-in-law's house.
Scientific investigation. And so they're all, we have spacecraft going to comets, to asteroids. And so we're all over the solar system now. It's a, it's a fun time to be alive because the solar system is no longer this distant place.
And when we come back after the break, as I promised before, we're going to talk about life, the search for life in the universe. What are the conditions that a planet or an object have to have in order for there to have life as we know it?
Because maybe this could be some stuff that life as you don't know.
StarTalk Radio, we're back. You know, over the break Chuck Nice and I were talking about this mission to Pluto and he was bugging out the whole time.
Yeah, well, first of all, you told me that this thing starts in 2006.
Yeah, it was launched in 2006.
And then you said when you, when we were talking on the air, 2015.
Yeah, it took 10, it's 10-year mission, yeah.
So what do you do in the 10 years?
Oh, so the PI is.
You shoot the thing up there and now you got 10 years.
You go to the Bahamas for 10 years. No, I think they're, I'm told that they're working hard trying to make sure. No, you actually can take images, you test the equipment along the way.
You get data, this, it passes other planets, it needs a gravity assist.
Okay, gotcha.
You know, it's, it's doing thing, it's, it's not just a...
But see, the thing is Pluto is moving.
Yes, it is.
So...
Not very fast, but it is moving.
But yeah, so now you're, you're, you're shooting a rocket at a moving target.
Yeah, you're not shooting where it is, you're shooting where it will be when you get there.
Or at least you hope.
Well, that's when, laws of physics, you don't have to hope.
Oh, really? Is that, I'm, so, okay, good. So it's not like, you know...
So there.
Hey, man, uh, we got here, Pluto's not home.
Yeah, that would be bad.
It's like, yeah, it was here three days ago.
Yeah. Okay, so cool, actually.
Newton's laws of physics allow you to hit it where it will be, when it will be there.
Hence the gravitational adjustments. Is that what you're saying?
Uh, no, we know the gravity fully and advance the whole route.
Aw, man.
We have the capacity to make tiny mid-course adjustments if it's something we hadn't figured.
But lately, these things have been going without hardly any use of fuel.
Oh, yeah, yeah. It's, it's a, it's a, it's a lob shot, basically.
So what, now, we're not going to Pluto to look for life. It's too cold, it's too far, it's too dark, it's too everything that we can imagine that could serve life. But there are other places in the solar system that could serve this need. And we talked to two of my favorite colleagues, Steve Squyres and Heidi Hammel, two sol- we had a geek fest in my office.
Geeking out.
We were geeking out on the solar system.
They're just giddy, I can hear the giggling now.
We were giddy. Let's, let's find out what they say about a search for life in the solar system.
We love the planets, but the real goal is we want to find life. Mars has been a seductive prospect for life since the begin- since Lowell. Yep. Okay, Percival Lowell. Yep. Thought he saw Martian.
A little misled, but you know, he had the, he had the right idea.
His heart was in the right place.
Yeah, his heart was in the right place.
You know, he's the one who invented the canal story.
You'll quickly tell us that, the canal story, real quick?
Well, basically, what happened was that people looked through a telescope and they saw...
Hundred years ago.
Yeah, a hundred years ago, in moments of brief atmospheric clarity, they could see what looked like a fine network of straight lines on the planet's surface. And they were so straight and so regular that the people looking at these concluded that not only were they evidence of life, they were evidence of intelligent life. Now, they were correct, but the life was at the wrong end of the telescope. What they were seeing was an optical illusion.
And didn't know enough about illusions to.
Yeah, and in fact, there's nothing of the sort on the surface of Mars, but as we've learned in recent decades, Mars is very interesting in other ways.
Nonetheless, nonetheless, with possible evidence of running water. So the two water places that I know of is Europa, one of Jupiter's moons. One of my favorite places just to think about, to dream about, because I want to go ice fishing on Europa one day. And of course Mars, possibly under, under surface aquifers. And Heidi, how has Europa kept warm?
No, it's really kind of a gravitational tidal pumping with the other moons around Jupiter that kind of bend it. You know, the analogy I use is if you take a credit card, you bend it back and forth.
I try not to do that.
With old credit cards.
He's a co-hanger.
A co-hanger, a paperclip, how's that? You bend the paperclip back and forth a whole bunch and you touch it, you feel it gets warm. Right? Same thing is happening with this moon, you know, Europa and Io, they're kind of getting flexed and bent, flexed and bent, and it heats them up. And you know what? Don't forget about Enceladus when you're talking about water worlds. Enceladus, we now know is just blast, moon of Saturn.
Little tiny one too. It's also tidally heated.
Tidally heated, the same flexing to heat it up, but it's just blasting water out of its southern pole.
Geysers, basically.
Are these not ice volcanoes or, or what are, I don't know, it's liquid water coming out?
It, it's water.
Yeah, you can think of it as volcanoes, it's just that the magma is water instead of being molten rock.
I mean, you could, if you.
It's pressure that builds up and it spews forth.
It's water. I mean, you could, if you flew a spacecraft through it and collected it and you were able at a room temperature, you could drink it.
And of course, every place on Earth, we have liquid water, we have life, so therein is the temptation.
That's where the temptation.
What would you bet on Mars or Europa as a, the place, if there's life other than Earth in the solar system, that we would find it?
Today.
Today. Yeah, see, that's the question, is that you're talking about life today or life ever existed? Because it's a different question.
I would say Europa. If I knew how to do Europa not Mars. If I, if I knew how to If I knew how to do submarines on Europa, I wouldn't be screwing around with rovers on Mars. Ooh, ooh.
What if you dug down into Mars? Doesn't it get warmer?
Yeah, it does.
Yeah, you got, you got water as you get further.
Yeah, I don't know how, I don't know how to drill down hundreds of meters on Mars either.
Well, you don't know, you know, if you don't know how to drill on Europa.
But if they're really, if they're, yeah, I mean, they're both huge technological challenges, but if there truly is. Wait, just, how thick is the ice on Europa approximately? We don't even know for sure that there's an ocean there. Well, I, I saw the picture.
Ten kilometers, a hundred kilometers.
It's unproving, it's likely, but it is unproven. I saw the ice, it looks like.
I can make a picture for you, Neil.
It looks like, but you're gonna spend tens of billions of dollars doing a submarine mission to an ocean that you don't know for sure exists? Okay, alright. We got work to do there still.
Yeah, we gotta learn a lot about the environment.
I want this to happen in my lifetime. Uh... I've got two key people here. Eat, eat healthy, get lots of exercise, okay?
Go on that low calorie diet.
Seventeen hundred calories a day, that'll get you an extra year per year or something.
Wear my seatbelt, too. Yeah, yeah.
But you know what, um, what might happen in your lifetime is we may find Earth-like planets around other stars in a distance from that star where water could be liquid.
Yep, I'll tell you another one that could happen in your lifetime, and that is bringing rock samples back from Mars that contain definitive evidence, one way or the other. Fossilized. On whether or not there was life at the location from which the rocks came. And ideally, you get to choose your own rocks. Yeah, see, I mean, we have rocks from, in fact, I'm sure you've got them in your museum here. We've got rocks from Mars here on Earth in the form of meteorites, but these are rocks that literally fell from the sky. We don't know where on Mars they came from, we didn't pick them, they just came here. They don't have the pedigree that you need to order them. Mars, Mars is a very, very complex place geologically, and to be perfectly honest, most of Mars is pretty boring. Most of Mars is just covered with lava, very dry, very desolate. Solid lava.
No evidence that water was there, solid lava, yeah. And, and, and you know, very ancient volcanic rocks and evidence for life, you're not going to find in a place like that. To find it, you gotta go to the special places where you have the right minerals, the right sediments, the kind of stuff that can preserve evidence of ancient habitable watery conditions. And those are few and far between.
Okay, so we have Mars as a good example of where to look for evidence of past life. Europa as a place to look for possible evidence of current life.
You could, you could look for evidence of current life on Mars as well, but you probably have to drill deep and that's hard.
Geek Fest continues.
Man, that was serious.
Now Chuck, you realize that interview in my office took place a few weeks before the announcement that we found Goldilocks planets orbiting, exo-planets orbiting distant stars.
Yeah, where they're close enough or far enough from the sun where they can have water.
At the right distance, not too close.
Not too close, not too far.
Evaporate too far.
Hence the Goldilocks, right?
The Goldilocks, exactly. And so for them to say, this will happen in your lifetime, then happen three weeks later, you know?
You ask, you receive.
Yeah, like they forked it up. We, we have a tweet that someone asked from a tweet, this is Trudvertite, that's the Twitter handle, is the thought of exploring and terraforming Mars even relevant if we can't even take care of our own planet?
Yes, it is. Let me just field this one.
Okay, this one goes to Chuck, apparently.
We're going to need a place to go.
After we mess up the earth.
Cause we're screwing this one up royally, buddy. So we need a place to go.
Okay, so you, you have the opposite sense of this question. This question is, we don't deserve another planet if we can't take care of our own. You're saying it's because we can't take care of our own that we gotta have the planet. My, my reply is if you're terra, if you have the power to terraform another planet, you have the power to fix your own planet.
Just think about that.
If you have that much control over geoengineering.
What's a, what's a, what's a few degrees warming? Just crank the knob that lowers the temperature back again.
Exactly, because you'll know what to do.
You know exactly what to do.
Basically, you'll be able to create a, a geothermal thermostat.
A thermostat, exactly. Awesome phrase.
Chuck.
Yeah. I just, I don't even know where that came from.
A geothermal thermal thermostat, awesome.
Dude, hanging out with you is rubbing off on me.
Ooh, that just smelled good.
I felt smart for a second. Still don't know what I said.
And so we got these.
And so, so you got these places, like, you know, Heidi raised an interesting point. And that if you're looking around for other solar systems, star systems, we don't know yet how common our star system is.
We've got these eight planets, get over it. We've got eight, we've got sort of Earth and Mars sort of in the Goldilocks zone, but we have these places outside of the Goldilocks zone kept warm. In the case of Jupiter, it's Jupiter's gravity stressing the moons. By the way, in the old days, people said, let's find a planet with life. But you can have a moon, if the moon is big enough, why not have life on a moon?
And if the host planet keeps the moon warm, you don't even have to be in the Goldilocks zone of the host star.
So now, when you guys were talking about this, wait a minute, tidal heat.
Oh, tidal heat, yes.
Is that when the gravity moves the planet back and forth or stretches?
It stretches.
And that creates the heat?
It's a stretching kind of gravity. And it does that to the, to the water, the oceans of the earth that stretches them and you, Earth turns inside and out of the stretched ocean on the earth.
Yeah, oh yeah. More about tidal heating when we get back on StarTalk Radio.
Welcome back to the show. You know, there's a mission up there right now getting data like gangbusters called Kepler.
Kepler.
Kepler, named after the famous mathematician, from the German mathematician, late 1500s, early 1600s. He was the first to write down an equation that told you how planets orbit the sun. They call Kepler's three laws of motion.
It was awesome. First, the first law of science in the universe was Kepler's three laws.
Kepler's three laws of motion.
So basically predictive physical science has only really been around for 400 years since he wrote down those equations.
So we're pretty new at this.
We're kind of new, yeah, compared to other stuff that humans have been doing. So, so Kepler is specially designed to find earth-sized planets orbiting sun-like stars. And there's a recent data that was released that had a set of a thousand stars. A thousand planets orbiting other stars. And so it tripled the number of total. So we went from 500 to now 1500 stars, 1500 planets.
1500 planets.
In orbit around stars that are not the sun.
And out of those, there's about 40 or 50 Goldilocks planets that were found.
So there's about 40 or 50 other Earths floating around out there.
That could sustain liquid water.
That could sustain our life or have water.
Or Jupiter-sized planets with moons that are outside the Goldilocks zone. So we're casting a pretty wide net in the search for this. Do you realize this whole field, the search for life in the universe? It's called astrobiology. That's a term, if you went 20 years ago, the term never, didn't even, no one knew how to use it.
Nobody even knew.
It was not really part of the parlance of scientific discourse. And it's a field essentially invented by NASA.
Right, so 15 years ago, that would have been just called BS.
Yeah. Well, you need data. Data converts BS to real, to real discourse. Carl Sagan was, of course, a very early proponent of the search for life in the universe. And we can say, we can call him the father of astrobiology in that sense.
Although there are other people who had done sort of earth-based bio experiments that preceded that. But you want to stay current on the frontier of astrobiology?
There's an online NASA magazine called AstroBio.
AstroBio.
Dot net.
The AstroBio.net.
For all of your astrobiology needs. It's AstroBio.net.
So now, one of the, one of the great frontiers here is where you have to ask, how are you going to explore? The nearby planets or the distant ones? Do you send a robot? Do you send a human?
Do you send a robot to do what a human can do? Or like, that's, this is the major issue, a major question. And I brought that up with Steve Squyres and Heidi Hammel. And let's see what, what their take is on it. One of them is a geologist and one of them is a telescope astronomer. Let's see where they take us on this issue.
Given the choice, because it costs more to send people than to send robots. If you had the choice of sending 30 robots to 30 different locations on Mars, or you going yourself? As a scientist, not as adventure explorer, Indiana Jones hat-wearing expedition head? I'm talking about... Well, how about we talk about sending you instead?
Yeah, wouldn't he be able to come back?
I forgot about whether we should bring him back.
Now, look, I see where you're going with this.
Where's the trade off?
The answer, my personal answer, is that I would send a human. Okay, and I'll give you two reasons for that. One reason is that what humans can do is so much greater than what robots are capable of now or for the foreseeable future.
Wait a minute, every time we send, every time we send a human, they bring out a black box that makes the measurement. Well, why not make the robot pull out the black box?
No, no, no, there's, there's much more to it than that. Okay, Neil, I have spent the last 20 years of my life trying to design and operate robots that can replicate what a human might be able to do on the Martian surface. What our rovers do in a day, you and I could do in about 30 seconds. That's one thing. The other thing is that humans have a capability to synthesize information, to digest it, to figure out the next thing to do, and to improvise. Robots can't improvise the way humans can.
It's not just that we're not there yet. I mean, Moore's law, get us a, you know, this ever increasing rate of.
I think you've got, you've got a couple of million years of evolution to go to that point.
We're, we're very, very far away from that. The other reason that I would send humans.
So the brain is still a pretty good device.
Terrific process.
Very, yeah. The other reason I would send humans is that humans have a capability to inspire that robots simply lack. Someone once famously said, nobody's ever gonna give a robot a tectrotape parade. And there is something to that. It's a little squishy, it's a little intangible, but I will tell you that our rovers were built by people like me who grew up in the 60s and 70s watching Mercury, and Gemini, and Apollo on TV, and dreaming of sending spaceships to Mars someday. And now we do that, okay? We were inspired by what we saw as kids, and I think sending humans does that in a way that robots never will. So I think there's a real value to it.
Where do you want to go? We could send you somewhere and bring you back.
You know, there's a lot of great stuff in the solar system to see. And just picking off the low hanging fruit, you know, I'd, I'd love to.
Where would you go?
Where would you go? The next place that I would go.
The fruit wouldn't have to be low hanging. Reach for it. Where would you go?
I'm so intrigued by the outer solar system because we know so little about it.
It's good scientific. Juice is flowing, yeah.
Yeah, we just know absolutely nothing about.
You're drawn to where you are most ignorant.
Yeah, because that's where you learn the most.
Most people are only comfortable where they know the most, but.
Oh, no, I, I, I wanna, I wanna, you know, uncover some of these, these things that we just don't know.
So give me a place.
I would like to go to Neptune.
Neptune, yeah. Neptune's a beautiful place. Orbit Neptune.
Yeah, because, you know, that planet system, not just the planet itself, but it's got an incredible ring system that's chunky and, and it's not smooth and beautiful like Saturn's. It's clumpy. It's very odd, very dynamic. It's changing with time. It's got a terrific moon called Triton, which was captured. It wasn't born with Neptune. It was some object that just got oops too close and Neptune.
Stolen.
Stolen, yeah.
Grabbed from interplanetary state.
This thing is like a twin to Pluto and it, we know that it has.
Triton is a twin.
Triton is a twin to Pluto. We know it has ice volcanoes. It's got geysers. We've seen them. And so this moon is dynamic and change. So the whole planetary system has something for everyone. I mean, we just learn so much.
So you're, you're attracted by the abject ignorance of what we know of the system? Of course, it's just really alien. It's a really alien place.
It's very different. I mean, these ice giants are, are just so different from Earth. I mean, they don't have surfaces. You couldn't land on it, but you could land on one of its moons and that would be.
See, since I'm fundamentally a, like a galactic person, not a, not a planet person, my destination within the solar system has nothing to do with how much we know. It's just what looks the coolest. So where, so where would you go? I would so go to Titan and just, and just watch Titan. The, that's the one with the rivers of methane.
It's got lakes, lakes in the holes.
Lakes of liquid methane and meanwhile you're orbiting Saturn. Well, I'll tell you, you, you, if you wanna go there, you really better eat healthy and get plenty of exercise. It's gonna take a while. All right. Thanks, guys, for being on StarTalk. Chuck, you know, if we find life on Europa, you know what we should call it?
What?
Europeans.
So Chuck, take us out of here. What do you?
You know, I was listening to that and I could just think, you know, if... The advantage of sending a robot is, you know, they're never going to ask, "Are we there yet?"
You've been listening to StarTalk. I'm Neil deGrasse Tyson, and as always, I bid you to keep looking up.
Page updated October 26, 2026 · transcript and summary are machine-generated
