Planetary Radio: Space Exploration, Astronomy and Science - Is Anybody Home? Assessing A Planet's Habitability

Episode Date: January 9, 2012

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Assessing the habitability of other worlds, this week on Planetary Radio. Welcome to the travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. Planets, they are everywhere, but can they support life? And as Star Trek's data might say, how can we narrow the search pattern? Life forms, you tiny little life forms, you precious little life forms, where are you? Astrobiologist Dirk Schultz-Hemakek and his colleagues have come up with the analytical tools data may need. Our moon may not be teeming with life, but we're still learning about it, as you'll hear from Bill Nye.

And stay tuned for What's Up with Bruce Betts. We've got a great new contest and a great prize for the winner, along with Bruce's usual cosmic goodies. A quick visit with Emily Lakdawalla will get us started. Emily, Happy New Year. Welcome back from vacation. I guess we're going to start seeing some new blog entries. Yeah, I had a nice break, learned how to ski, and it was excellent, and now I'm raring to go for 2012. Good. Didn't break your typing fingers. So let's jump right into it with a couple of older entries that you had. The most recent of these, December 30th, What is Space Exploration Worth? Nice essay, a bit of a departure for you. Yeah, I don't know. I guess the end of the year caught me

in a philosophical mood, and somebody had asked me during Curiosity's launch, which was of course last month, why are we spending $2.5 billion to send a rover to Mars? And it is a lot of money, and so I reflected on that and wrote down what I thought, and I hope my readers liked it. I highly recommend it. It's a very even-handed piece so I reflected on that and wrote down what I thought, and I hope my readers liked it. I highly recommend it. It's a very even-handed piece from someone who obviously has a bias, but, you know, we're the Planetary Society people. What do you expect? You also, the day before that, December 29th, had a look at what's up in the solar system in January, but you kind of looked across the whole upcoming year.

Yeah, in January, I like to look ahead and see what's going to happen. And this is an interesting year, especially in comparison to last year when there were four spacecraft launches. This year, there's no new planetary launches. The main events, I think, are going to be Curiosity's landing on Mars in August and Dawn completing its mission at Vesta and departing for Ceres also this summer. But really, I think the main news is that we've got 12 spacecraft currently sending data back from planets across the solar system from Messenger and Mercury,

Venus Express from Venus. Cassini is going to be flying close by Enceladus three times in March, April and May. There's an awful lot to look forward to also opportunity exploring a new rim of a crater at Mars that is just, it's like it's a whole new mission for that rover. All in all, it's going to be a very active year, just maybe not quite as eventful as last year was. You also have a section called Cruising From Here to There, Lots of Things in Transit. That's right. There's New Horizons on the way to Pluto, Juno on the way to Jupiter. Deep Impact is actually retargeted for a 2020 encounter for a near-Earth object that could be a future target for human exploration.

So there's also a lot to look forward to in the years to come. That is a December 29 entry in the blog from Emily. New stuff coming up now that she's back from vacation for the new year. And Emily, I look forward to talking to you all throughout this year. And I'll have plenty of news this week, I promise. Emily Lakdawallis, the Science and Technology Coordinator for the Planetary Society and a contributing editor to Sky and Telescope Magazine. Time for our first conversation actually recorded in the new year with Bill Nye, the Science and Planetary guy, CEO of the Planetary Society. And I take it, Bill, that you want to talk about

the new moon. Not the new moon, but the new moon. The moon part that we're just discovering about our own satellite, the Earth's moon. It is a remarkable time. So these people in Australia, digging around, they're geologists, who wouldn't be, and they found Tranquillite, Tranquilityite, named after the Tranquility Basin where the first humans landed on the moon back in 1969. And everybody thought that this Tranquilityite was unique to the moon. The only place you would find this is on the moon because that's where they had a volcano happening at the right time, at the right temperature, compressing the rock to just a certain amount. at the right temperature, compressing the rock to just a certain amount.

And so they found this same stuff for the first time in the Pibara region, which if you're into Australia is way in the west, north of the big city of Perth. What it means is that the Earth and the Moon have a little more in common than people thought. And by the end of this year, we're going to know even more because there are two spacecraft, the GRAIL spacecraft, the Gravity Recovery Interior Laboratory spacecraft, and they're going to figure out what was going on inside the moon in ancient times. And so we'll learn more about how planets form, and we will learn more, ultimately, Matt, about where we all came from. And I remind us that the GRAIL spacecraft are derivative or part of the same big idea as the GRACE spacecraft, which were Gravity Recovery and Climate Experiment, which orbit the Earth. And Matt,

I'm excited about this. It just shows you how connected we all are. These planetary bodies in our solar system orbiting the Earth, it all came from the same thing. And the more we know about this stuff, I guarantee you we are going to make discoveries about our past that will astonish us. That's not one I would want to bet against. Thank you, Bill. Thank you, Matt. Tranquility-ite. And these spacecraft are only 25 kilometers above the surface. I mean, it's 15 miles. When you look, if you're in an airplane, you can see 10 times that far. Yeah. This thing's coming right over your head. And then the Lunar Reconnaissance Orbiter, which is part of the whole big picture, it's coming right over your head

if you were standing on the moon. I should pull back. It's an exciting time, Matt. We are exploring the moon while we do this radio broadcast here on Earth. I've got to fly. Bill Nye, the planetary guy. Who is the CEO of the Planetary Society. I'll be right back to talk about the habitability and evaluating the habitability of other places around our solar system and elsewhere in the universe. Hundreds and hundreds of world-circling distant stars.

Soon we will have found thousands. Which among them can support life as we know it, or otherwise? What we need is a scoring system that considers all of the known and some of the speculative factors. That's exactly what a group of scientists has just done. Astrobiologist Dirk Schultze-Mackach of Washington State University is lead author of the paper describing their proposal. Dirk is also the co-author of Cosmic Biology, How Life Could Evolve on Other Worlds.

I got him on the Skype line a few weeks ago so that he could tell us about what this international collaboration calls a two-tiered approach to assessing the habitability of exoplanets. Dirk, thanks so much for joining us on Planetary Radio. It was just this morning that, as we speak, there were these announcements from the Kepler team, including this confirmation of Kepler-22b, this planet that circles a star that is very much like our own, that is only 2.4 Earth masses,

and is smack dab in the middle of the Goldilocks zone. I don't know. Is this exciting news for someone in your business? Yeah, absolutely. And thank you for having me on your program. Yeah, that is actually extremely exciting. And it was really only a matter of time until we catch really an Earth-type planet in a kind of Earth-type of an orbit as well. So you certainly have considered, you and this team that recently, well, actually this month is having this paper published in Astrobiology,

you considered Earth-like planets, but you didn't want to limit it to that, did you? No, of course not, because what we learned from our own solar system is there's so many different various scenarios where we can imagine life. Like, for example, in the ocean of Europa, Europa being one of Jupiter's moons, that there below could be a subsurface ocean, and you could very much imagine, like on Earth, at the hydrothermal vents, life being there located, or Titan even being more exotic with hydrocarbons and organic compounds on Titan. So we really want to be open-minded. And, of course, there is speculation about life that would be very unlike what we know on Earth. I know your colleague Chris McKay likes to speculate about life on that incredibly

frigid moon, Titan. Yes, absolutely. And we bounce regularly ideas to and fro us, and especially about Titan, because Titan is really the only other body in the solar system other than Earth that has liquids stable on its surface. And in that case, it's hydrocarbons with methane, ethane oceans. You have methane rain on Titan. You have compounds like acetylene, which give you a lot of energy. If we understand the building blocks of life right, so we very much could have their life. And the most exciting thing about Titan is it would be very different than the type of

life that we have on Earth. I'd like to talk more about this very foreign possibility of life, completely unlike Earth. But let's talk first about the first of these two indexes or indices that your team has come up with, the Earth Similarity Index. Well, the Earth Similarity Index is really giving the physical parameters of Earth, being the size at the distance from the sun. It doesn't say anything about habitability, really, because the moon is a pretty big object and ranks pretty highly on the Earth similarity index. So this is really very narrowly focused on finding, if you want, a second Earth.

You consider a lot of other bodies. In fact, the paper, which is titled A Two-Tiered Approach to Assessing the Habitability of Exoplanets You have tables, and there are some charts in here, that put Earth up at the most habitable. Not surprising, because it's obviously the only place that we know as well. Yes, that was the case, but basically because of the bias that we're starting off Earth, and we say, okay, at the very least, we know that on a planet like

Earth there can be life via the proof of that. So this is the first really conservative approach in going, okay, let's look for an Earth-type planet, consider those measurements that we actually can get nowadays. For habitability assessments, you usually need more sophisticated measurements that we don't necessarily have. So we really focus at the beginning just on the Earth's simulatory index. Let's talk about this other index, the PHI. What does that stand for? The Planetary Habitability Index. And this considers many other factors, but it's the algorithm that combines those factors that I think I find the most interesting. Yes, we came out with a scheme where we started out to be very open-minded. In order to score high on the Planetary Habitability Index,

for example, you don't need necessarily water on the surface, but you do need a liquid on the planetary habitability index, for example, you don't need necessarily water on the surface, but you do need a liquid on the surface that could act as a solvent. Then what we consider too as advantageous for the planetary habitability index is, for example, a magnetic field that could protect from cosmic radiation. Another thing is an atmosphere, a relatively thick atmosphere that can protect the surface of that planet or moon. And in the case of Europa, you have an ice layer above it. So that would be another permutation of that parameter. So we put all this different kind of parameters together and then develop, yes, like you say, an algorithm or an equation and come up then

with indices, with 1 being the highest and 0 being the lowest. And so Earth, being the only planet we absolutely know to be not just habitable but inhabited, gets a perfect score, basically. Actually not. Oh. And it's kind of funny because you have to see it a little bit in the time dependency. Early Earth gets a perfect score of 1 because there was a lot of tidal interactions.

Our moon was much closer, and with that additional energy. Current Earth actually only gets a 0.96 on that habitability index. Well, I don't know. I feel like I should speak up for our home planet, but I find that fascinating that you actually, in this scale of consideration, that you can actually imagine planets that may be more habitable than our own. Right. One example is Mars, and it shows really the limitations of the approach because what we look at it right now is what we get. We don't know what has happened to that planet billions of years ago. And the best example for that is Mars, because early Mars was actually relatively habitable.

I mean, you had liquid surface bodies of water on Mars. We don't know exactly for how long, but they were there. You had running water. You had a thicker atmosphere. You had a magnetic field. So early Mars would score relatively high on the PHI. But current Mars comes out not really that great because the atmosphere is thin. There's no magnetic field anymore.

So it comes out, I mean, still with Mars and Titan in our solar system, Titan slightly higher than Mars. It still comes out pretty high. But early Mars would have scored very high. And this, when we observe planets in other solar systems, mostly now exoplanets, we have no idea about the history of that planet. There's more ahead from Dirk Schultz-Semacher as we begin scanning for life in our solar system and beyond. This is Planetary Radio. I'm Sally Ride.

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Planetary Radio listeners who aren't yet members can join and receive a Planetary Radio t-shirt. Members receive the internationally acclaimed Planetary Report magazine. That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. My guest is astrobiologist Dirk Schultz-Imacher of Washington State University. He is lead author of a paper titled, A Two-Tiered Approach to Assessing

the Habitability of Exoplanets. It's in the December issue of the journal Astrobiology. We have a direct link to the abstract at planetary.org slash radio. Dirk has been telling us about the two indexes proposed in the article. One is the Planetary Habitability Index, or PHI. Can you say something about another of the factors that the PHI takes into account, and that is a solid surface or substrate, which surprised me a bit because obviously there are so many planets that we've already found around the galaxy that probably are like Jupiter and

Saturn and don't really have a solid surface unless you go down really deep. Right. The idea is basically that in order for organism to function, microbial organism, even a more complex organism, you need liquids because only liquids do release a nutrient exchange. And the organism itself is partially solid and partially liquid. And we know that on those interfaces between a solid and liquid, there's the most exchanges happening. If you only have gas, things are just simply to dilute. I mean, we don't want to say it's impossible because we really don't know that. That would stretching it. But to us, it seems to be pretty unlikely that life could just exist in a cloud

form because there would not be enough interactions. And it would be really difficult to have a kind of a boundary, the boundary that membranes on Earth take in, like for microbes also. Why did you and your team feel that it was important to develop these indices as we discover more and more exoplanets? Well, as you said at the beginning, we have now Kepler just made a new press release and have discovered many more planets. We're getting more and more of those. And at that time when we developed the index, we had between 500, around 500 exoplanets. At the time it was published, it was more than 700, with being another 1500 or so unconfirmed.

And so we will in a few years we will have several thousand at the very least. And we do have to have some kind of an idea how to prioritize it and say okay this and this planet we really want to take a closer look. As you know there's a limited budgets around and limited time of researchers as well. So we have to focus on those really, where we have a higher chance of the extraterrestrial life on Earth, but also for habitability and pool our resources into those. We wanted to have an index that's really objective, that it's not Earth-centric, where we only say, okay, it has to be exactly like Earth, but we wanted to be

that it's relatively open-minded. And will the work of refining these indices, is this going to continue? And what tools are going to be useful as you do this? Yes, I mean, the refinement will continue, and we made a very strong point in the paper like that, that as more and more information becomes available, the index of especially the exoplanets will have to be revised. It usually probably will go up as we get more. If we, for example, know only, okay, that is a planet that is similar to Earth, but now we find out it has an atmosphere, or a thick atmosphere, so that would mean, okay, the index has to be revised, it goes a little bit up. If we find out, oh, we detected a magnetic field as well, then it would go further up. If we now find that

this planet is barren, that there's no liquids on it, it would go down. If we find that it has oceans on it, it would go really up. So basically, as more and more new information becomes available, it would be updated. There's a couple of missions in the workings or in the planning that would really give us more information. What we really need to know is we have to get the spectra of the atmosphere on that planet and, you know, higher resolution, and we'll see how far we can get.

Dirk, it's exciting work. It's an exciting time that we live in, and your team has probably given us a way to better evaluate these planets as we discover and become better able to investigate them. And I bet you're like me, hoping that we actually find life, not just that one of these planets is habitable, but that we've finally found life elsewhere in the universe. Yes, that would be very nice. That would be my wish, too. Thanks so much for joining us on Planetary Radio. Thank you for having me. My guest has been Dirk Schulze-Mackert, whose name I have been trying to get correct, but I'm sure I still did not.

He is a professor in the School of Earth and Environmental Sciences at Washington State University, but he is also the lead author of this new paper in Astrobiology, a two-tiered approach to assessing the habitability of exoplanets. And you might want to also look into his science fiction book, Voids of Eternity, Alien Encounter. I happen to know it's available on Amazon, and that's where I think I'll be checking it out. Well, we're going to check out the night sky next. That'll be during our regular visit with Bruce Betts for this week's edition of What's Up. Back in Bruce Betts' office for this week's edition of What's Up. No live audience,

so tell us about the night sky. Okay, we still got Venus dominating over in the west in the early evening. Jupiter high in the south also in the early evening. Super, super bright. Mars starting to get fun, festive, and bright as it approaches its March 3rd opposition. And nearly closest point to Earth at that time. So right now it is getting bright. It is rising around 10 p.m. in the east. And you can see it high overhead in the pre-dawn,

looking not surprisingly reddish. But it will keep brightening. I'll keep you posted over the next couple months. Was this second week of 2012 a big week in past years? Yes, it was, Matt. Some very interesting things happened. In fact, if we go back to 1610, Galileo, that wacky guy, discovered G ganymede largest moon of the solar system not

that he knew that at the time not bad 400 uh two years ago i'm quick you are quick even more recently six years ago hoyen's probe landed well went through the atmosphere and actually ended up landing successfully on titan and then five years ago, also this week, we had the Stardust spacecraft return samples from a comet down to Earth. That was five years ago? Good Lord. Time flies when, well, time just flies. Stardust flew.

Stardust flew, still flew, went off and did a whole other mission afterwards and flew by Comet Temple 1. Alright, let us go on to Random Space Effect. Had that pizza for lunch, huh? I see if I try to do it, it'll

I just I have this impairment my children make fun of me for, which is my accents just change from one to another. And they're all terrible. And it's just not good. So let's go on to the random space fact. Ganymede, that moon, discovered 402 years ago.

Largest moon, also not surprisingly perhaps, has the highest mass of all the moons in the solar system. It has about twice, almost exactly twice the mass of the Earth's moon. That is big. Why, yes, it is in the land of moons. But bigger than some planets, right? Things that we still call planets. It is. It's larger than Mercury by quite a bit, but not as massive as dense Mercury. And we may even come back to that in some future Random Space Fact. But in the meantime, let us go on to the trivia contest. And we asked you, how far did the Mars Exploration Rover Spirit drive on Mars? How'd we do, Matt? A respectable post-holiday response here.

Some very good ones. Here's my favorite response. Not the winner, I'm sorry to say. Ed Lupin, he said that Spirit's odometer may have been rolled back by some shifty Martians to increase the resale value, but it did read basically 7.73 kilometers, which is about 4.8 miles. Yeah, before the Martians put it up on blocks. That's right. That's what it measured. Who was our winner, Matt? The winner, I think a first-time winner,

Valdeck Bednarczyk. I didn't get a pronunciation guide here, so you get what you get. In Poland, one of our Polish listeners, we have a bunch who, in fact, did come up with that figure of 7.73 kilometers. So, Valdeck, congratulations. We're going to send you a Planetary Radio t-shirt,

but an even better prize this week. Wait, wait, wait. Stop knocking the Planetary Radio t-shirt. It is the greatest prize in the universe, but a close second would be our new prize. Tell us about it, man. We've gotten some things from these guys in the past, but this is the coolest thing yet from Livio Radio, our friends at Livio Radio, who now have this new device called the kit, the Bluetooth Internet Radio Car Kit. And it's this very cool thing. I'll show it to you. There it is. It's up on a stock. Yeah. And it plugs right into the cigarette lighter,

but it's self-supporting. You don't need to mount it on the dashboard or anything like that. And it's got a cute little dial and it pulls in over 45,000 internet radio stations, sends them wirelessly by Bluetooth to your iPod Touch or your later model iPhone, but it's also a hands-free Bluetooth phone kit for the car. So not only does it give you cool tunes, but it keeps you legal. And we got how many of those for staff? Exactly one, and not for staff, for the winner of this new contest, which we're going to describe right now.

We talked in the last couple weeks about the message encoded in Morse code on the wheels of the Mars Science Laboratory rover Curiosity, and that it says in Mars code JPL, a tribute to its builders, to its home. And this was actually a Matt-inspired contest, I must say. A cool concept. We're going to open it up for all of you. What if you had the opportunity to encode... No, no, if you had the curiosity.

If you had the curiosity and opportunity and spirit to encode a message on wheels of a Martian rover, for example curiosity, and you had only three letters to do it, what three letters would you use?

And assuming they're an acronym, let us know what they mean, what they say. Did I get it right, Matt? Yeah, you did very well. Okay, and we will judge that in our scientific way based upon some combination of humor, inspiration, and randomness, of course. Yeah, if you inspire us, that's great.

We tend toward humor because it's just how we roll. It's just how we roll. So, yeah, probably more chance on the humor. So send that. Go to planetary.org slash radio to find out how to enter. And we will happily read off the, as many as we have time for, the best of these entries. Your three letters to be left in the sands of Mars. That's cool. And a very cool prize. Alright, everybody, go out there, look up the night sky, and think, if you had everybody, go out there, look up the night sky

and think, if you had a radio in your head what channel would you tune it to? What do you mean, if? He's Bruce Betts, the Director of Projects for the Planetary Society He joins us every week here for What's Up That explains so much Get those contest entries to us

by 2pm on Monday, January 16. Planetary Radio is produced by the Planetary Society in Pasadena, California and made possible by a grant from the Kenneth T. and Eileen L. Norris Foundation and by the members of the Planetary Society. Clear skies. Thank you.