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Are we alone in the Universe? It’s one of the biggest scientific questions we can possibly ask. And yet, with rovers on Mars, missions planned to visit Europa and Ganymede. Powerful telescopes able to detect the atmospheres of exoplanets, we’re closer than ever to finding out the answer.
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Extreme Heat (Ready.gov)
Heat Wave Safety (American Red Cross)
Dragonfly (NASA JPL)
Mars 2020 Perseverance Rover (NASA)
Huygens probe (NASA)
Galileo (NASA JPL)
Juno (NASA JPL)
NASA’s Hubble Observations Suggest Underground Ocean on Jupiter’s Largest Moon (NASA)
Surprise! Pluto May Have Possessed a Subsurface Ocean at Birth (Scientific American)
Possible Life Signs In The Clouds Of Venus (EarthSky)
Viking 1 & 2 (NASA)
PODCAST: Craters in Northern Canada Offer Clues to Titan (CosmoQuest)
TWITTER: Mars Analogues on Earth
PDF: The paleoenvironmental significance of trace fossils in Devonian sediments (Taylor Group), Darwin Mountains to the Dry Valleys, southern Victoria Land (USGS)
Mars Sample Return (NASA JPL)
PODCAST: Ep. 588: Lunar Resources: Lava Tubes (Astronomy Cast)
Planetary Cave Exploration Progresses (Eos)
Narusawa Ice Cave (Japan Travel)
Crystal Ice Cave Tours (National Park Service)
What Are Extremophiles? (Los Cumbres Observatory)
The Microbes That Keep Hydrothermal Vents Pumping (Smithsonian)
The Use of Oxygen as a Biosignature in the Search for Extraterrestrial Life (LPI)
Evolution Of The Atmosphere: Composition, Structure And Energy (University of Michigan)
Exoplanet atmospheres (Uppsala University)
Transcriptions provided by GMR Transcription Services
Fraser Cain: Astronomy Cast episode 610 Confirming Alien Life. Welcome to Astronomy Cast our weekly facts based journey through the cosmos. We help you understand not only what we know but how we know what we know. I’m Fraser Cain, publisher of Universe Today and with me as always is Dr. Pamela Gay, a senior scientist for the Planetary Science Institute and the director of CosmoQuest. Hey, Pamela. How you doing?
Dr. Pamela Gay: I am doing well. How are you doing?
Fraser Cain: Good although it sounds like your being baked, steamed broiled there.
Dr. Pamela Gay: It is steamed. According to my sensors down here in the basement, it is currently 96% humidity, and it’s 102 degrees outside. Yeah. We’re not used to this here. And this is, as so many people here in the North American continent are experiencing, an unusually hot spring. And stay safe people. Get fans. Check on your neighbors. When I lived in Austin, Texas, it was normal that everyone had cooling stations that they could go to if they needed to and couldn’t afford AC. A lot of places aren’t designed for that right now and in these still COVID times, I know people are avoiding crowded situations like air conditioned shopping malls and movie theaters. So, take care of each other.
Fraser Cain: Yeah. That’s interesting.
Dr. Pamela Gay: Yeah. We’ll get through this.
Fraser Cain: We’re having another Junuary, which is a very cold, wet June. Temperatures got low. And so, we’re experiencing the opposite although we’re coming out the other side of it. And we should hit the mid-80s says my wife speaking in American. I don’t really know what that means. But –
Dr. Pamela Gay: Thirties.
Fraser Cain: – it’s apparently warm. So, yeah, it’s gonna finally hit us.
Dr. Pamela Gay: Yeah. We are getting your weather late next week when our nighttime temperatures are gonna get back into the teens and Celsius into the 50s in Fahrenheit. And our daytime temperatures will drop down where they belong in the 80s Fahrenheit, high 20s, lows 30s Celsius. And I’m looking forward to that and I suspect my garden is as well.
Fraser Cain: Yeah, yeah. All right. So, are we alone in the universe? It’s one of the biggest scientific questions that we can possibly ask and yet, with rovers on Mars, missions planned to visit Europa and Ganymede, powerful telescopes able to detect the atmospheres exoplanets, we’re closer than ever to finding out the answer. I got to admit this topic, it’s interesting, if there’s one part of my thinking that I feel has become really nice and nuanced, delving into shades of gray over the decades as my beard has turned shades of gray, I’ve really come to a deep understanding of how difficult it’s going to be for us to actually find life out there in the universe. Obviously, if there’s a big fish skeleton or even just like a bunny hopping around the rover on mars, then done, life confirmed. Let’s move on. But it’s gonna be tricky there. How difficult is it gonna be for us to find life in the universe?
Dr. Pamela Gay: I honestly feel like this is a two-part question where question one is how hard is it to make the needed detections, and part two is how hard is it to convince ourselves of that what we’re seeing is the result of life and not of some other crazy thing that’s going on out there.
Fraser Cain: Okay. Well, I think that’s great. Let’s break this into two pieces then. First, when we think about all of the vast array of scientific instruments that are deployed across the solar system and looking at the universe, what are the techniques that we’re trying to use to try to figure out if there’s any life anywhere else but earth.
Dr. Pamela Gay: Well, except with Mars, currently our primary, perhaps our only way of looking, is to look at the chemistry. We look at worlds like Titan and say that methane might mean there’s either geological processes or life processes that are creating this gas that we know breaks down in the ultraviolet light of the sun. And researchers like Chris McKay have studied other chemical signatures in the atmosphere and found things don’t balance out the way they make you balance equations in high school. And that means there’s something else out there throwing the everyday chemistry into something else. And that something else doing it could be life, or geology as we do not know, or chemistry as we do not know it.
Fraser Cain: But it’s funny, you said apart from Mars, and we’ll talk about that in a second, but nobody is looking at Titan right now in any meaningful way trying to see if there’s anything that’s pushing Titan out of balance.
Dr. Pamela Gay: Well, that’s a lack of spacecraft issue. Dragonfly will be looking.
Fraser Cain: Well, yes. Yes, exactly. Yes. Dragonfly will be looking. Perseverance will be looking. When you think about like right now, we haven’t even gotten to the point that we can look yet.
Dr. Pamela Gay: Yeah and this is a frustration that comes from a combination of the people who control the money saying scientists you’re not allowed to go looking for life. Just stop. Just stop. And when you don’t allow people the finances they need to build the instrumentation necessary, you don’t find the signatures of life. And the other thing is, this is just hard and until we have surveyed the different space systems, the moons of Saturn, the moons of Jupiter to identify where the places there could be life, it’s not worth building the expensive equipment necessary to go out and find that life. Cassini taught us that Enceladus sprays liquid into space that we can sample. That’s something. The Huygens probe taught us that Titan exists at the triple point of methane. That’s something. And Galileo, well it showed us in so many different ways how all these different worlds are icy and now Juno is continuing that mission showing us Ganymede it has its own subsurface water just like Pluto does.
Fraser Cain: And so, again, you’re showing that these are worlds and they have atmospheres but not any kind of sort of deep attempt to try sense if there is some kind of chemical imbalance that’s going on. When I think about what has actually been attempted, there’s like the analysis of methane at Mars. There was the Viking experiment where they fed soil nutrients and water and tried to see if produced some kind of chemicals. There was the discovery of phosphine on Venus, which is a weird chemical in the atmosphere. I’m out. I’m out of experiments that have been attempted so far.
Dr. Pamela Gay: And I think the Viking mission was an unfortunate life lesson for a lot of scientists because there were the researchers who looked at the data and said yes. There is life on Mars. And that was the hill they were willing to die upon and still are to a certain degree. And because of the collective yeah, we’re not going to repeat this experiment that came from NASA because of the near universal outcry of now just stop and be quiet, you can’t be right, anyone else is going to think not just twice but 20 times before they consider potentially risking their career and their reputation as a researchers on looking to replicate those experiments because if they replicate them and find those same potential sources of life, they don’t want to be forced to die on that hill alongside the Viking researchers.
Fraser Cain: All right. So, we’ve talked about just a few just halting attempts so far where the evidence has not been overwhelming. It has been inconclusive, the worst kind of evidence. But let’s talk about sort of the next steps then. What are some of the more serious strategies that have been proposed to attempt to find these chemicals out of whack, imbalance in a planetary system?
Dr. Pamela Gay: So, my favorite is Dragonfly and this is an exception to my normal never learn anything about a mission before it launches. And the reason it’s an exception is because of all of the work they’re doing in artic environments. With Dragonfly, they’re going to have a lander and I don’t know if you wanna call it a drone or a helicopter. They have a robot that can flit around and fly.
Fraser Cain: A rotary craft.
Dr. Pamela Gay: Yeah and they’re gonna be landing it near a fairly large crater on Titan. While Titan itself doesn’t get a whole lot of sunlight and is a pretty frozen world, when it gets hit by incoming space rocks, the energy of that impact will melt everything in the vicinity and allow all the kinds of chemical reactions normally tied to warmer places to take place. And right now, there are teams that are exploring a crater on Devon Island in northern Canada, the Haughton crater. And they’re trying to figure in this icy crater on earth that was formed in the permafrost what kinds of melt structures occurred? What kinds of organic chemistry took place in the ice, and where do they need to send Dragonfly to go looking for similar kinds of events on Titan? And they’re finding life can exist in this kind of crazy environment. The other thing that I’m looking forward to is Perseverance at some point is going to get out of the helicopter babysitting phase of its exploration.
Fraser Cain: Right. It’s started. It’s already mostly over. It’s moved into its actual science mission now.
Dr. Pamela Gay: Slowly.
Fraser Cain: That helicopter’s on its own.
Dr. Pamela Gay: But at some point, it’s gonna start digging up samples that can be looked at to see what is possibly in the samples. And there are what are called earth analogs, places on earth where the environment is not as deaf as the surface as Mars but is inhospitable in its own way. And there is a sandstone outcrop in Antarctica, Beacon sandstone outcrop. I don’t know why it has that name. Anyway, there’s sandstone in Antarctica. And if you go knock out chunks of it and study it correctly under florescent light and tearing it apart and looking at the chemistry of it, you find that there’s an entire ecosystem in the sandstone, not just one microbe but a bunch of life living off of each other’s byproducts. And there’s sandstone on Mars. And if you can get life living inside the rock, you can get samples of the rock with Perseverance and someday bring it back.
Fraser Cain: Right, which you just answered my next question, which was that perseverance doesn’t have sophisticated enough instruments on board to detect that complex web of biological interactions. It has some tools but nothing that sensitive. So, we need to bring those samples home and that’s like forever, like 2030s before we get some of those samples but fine. We’re moving forward. So, you’re gonna be able to take a direct sample, look through it, and actually hopefully see these kinds of really complicated sophisticated biological webs going on inside. That would be amazing. What else do you think is gonna be a way forward?
Dr. Pamela Gay: So, there has been talk, and this was actually part of the original Google Lunar XPRIZE, to develop robots that it’s possible to drop into cave systems. Any world that has had volcanos probably has volcanic tunnels, which we have talked about many times.
Fraser Cain: Mm-hmm. Yep, lava tubes.
Dr. Pamela Gay: And once you’re able to drop robots into those systems, they can go exploring in places that may be warmer due to geothermal effects that are protected from radiation by the rock around them, that are chemically interesting because they’re part of a volcanic system. And to go back to those earth analogs, here on earth we have high altitude caves in volcanic systems that support life. There’s some at Fuji in Japan, amazing ice caves. There’s the crystal caves in Lava Beds national monument here in the United States. And these systems have stalactites and stalagmites that are made out of water instead of out of limestone. And they have their own biology. Hopefully, we will get to the point that we can sterilize the bejesus out of a probe and tether it down into one of these caves and let it do the exploring and look in these safer places, these potentially warmer places to see does life find a way.
Fraser Cain: It’s interesting like with the field of astrobiology how much of the discoveries of the extreme places that life is finding a way to life here on earth is helping to really inform the plans for say these missions to other world. And a lot of those discoveries have been really recent, these discoveries as you say of life living within sandstone, of life living within these caves, the life around the hydrothermal vents at the bottoms of the ocean. We’ve only learned about these within the last couple of decades. And so, it’s almost as if we got too far ahead of ourselves wondering if there’s life on Mars when we haven’t even done an acceptable job of figuring out where there’s life on earth and by finding more life on earth, it will inform out ability to think about life on other worlds. So, yeah, we’ve talked about searching for life and kind of getting your robot hands on samples.
Dr. Pamela Gay: Hopefully, your clean robot hands.
Fraser Cain: Yeah, your clean, your bacteria infested robot grippers. But hopefully, clean and brining samples back so that we can study them here on earth. But I think one of the most exciting ways we could find life is out there in space with our powerful space telescopes. What’s that gonna take?
Dr. Pamela Gay: It’s gonna take two different things I suspect. 1.) We have to convince people that life forms regularly. We have already been able to prove because of all of the crazy place on our own planet that life keeps finding a way to exist that a lot of places are habitable that we didn’t think were habitable. Now, if we can go and look at those places in our own solar system and find why, yes. There’s life here. There’s life there. There’s life anywhere that life is capable of being, that will tell us that it’s easy for life to form. Now, if we don’t find life anywhere else in solar system given the fullness of time and exploration, it’s going to become significantly harder to convince people of what we find out there among the stars. Now, when we’re looking out there, we’re looking for things that are chemically out of balance and have chemical signatures that are undeniably related to life.
Fraser Cain: And that’s the tricky part.
Dr. Pamela Gay: Now, if you’re looking at a civilization, this is super easy. You go looking for all of their pollution. You go looking for the IR excess due to space equipment. There’s lots of little giveaways especially radio signals and things like that. If you have too advanced a civilization, that all goes away when they hopefully stop polluting and filling space with junk. But saying that world out there is starting to have life, this gets more complicated. And folks have done some really good models of how the earth’s atmosphere would’ve appeared at various stages in the evolution of life.
Fraser Cain: Yeah. I saw that paper.
Dr. Pamela Gay: And so, here we can say early on you’re going to have a methane rich atmosphere due to all the methanogens. You can say at some point you’re going to have a boom in oxygen, and then you start looking at all of the chemicals that are unstable and hard to create. And this is where phosphine was such an amazing potential result at Venus and right now, we’re at the point of not knowing whether or not phosphine was actually detected. Phosphine is one of those chemicals that is an easy thing for life to create but generally doesn’t spring into existence on its own in the pressures and temperatures that we see at Venus. So, we’re gonna be looking for these chemistries, these biosignatures.
Fraser Cain: Yeah. And I mentioned sort of my increasingly nuanced view of this whole situation that back in the day, we just thought if we look at another world and if we see the presence of molecular oxygen in the atmosphere of a world, that tells us there’s life. Oh, well, actually there’s lot of ways that natural processes can make oxygen. Fine, if we see methane, then there’s life there. Oh, well, turns out volcanism can make methane. Okay, fine. If we see ozone, no. There’s ways that natural processes can make ozone, sunlight, ultraviolet radiation. And so, you go down this list of chemicals, and they get more and more complicated, and more and more obscure, and you start to require combinations of chemicals out of balance with each other.
And if you went and talked to an astrobiologist right now and said okay fine, what is the thing that we need to be looking for? They wouldn’t be able to tell you. They haven’t really agreed upon a set of chemicals that if seen, give you this smoking gun proof of life. And they probably are still decades away of having this definitive answer. And so, once again, I think it comes back to what you mentioned earlier that once again, at earth, and considering the history of earth, and seeing what the earth looked like holistically, tells you what to be looking for out there in the universe as well not just one chemical.
Dr. Pamela Gay: And one of the things that makes it even harder is what we want to do is take high resolution spectroscopy of the atmosphere’s of planets. And what this means is we are able to shine light through a planetary atmosphere, and divide that light out into the biggest rainbow possible, and then look at the bright and dark pattern in that rainbow in the highest amount of detail possible, and look for all the individual lines that represent different isotopic ratios that represent different molecules, different atoms. We know that plants preferentially pick out more of one isotope of carbon than another. And to get all of this detail, however, you need to have a planet that passes directly in front of its star and isn’t completely drowned out by the light of its star. And to get that kind of situation, you ideally want to have a fairly big planet in front of a fairly small star. But small stars have more complicated atmospheres. So, the measurements we want are incredibly difficult. In an ideal world, you have a star that doesn’t have any of its own fancy banding. But stars that hot, they’re probably not gonna have life. We don’t actually know any of these things. That’s my gut speaking, but it’s a hard set of measurements to make.
Fraser Cain: Yeah and so, this feels like a theme. It feels like a book or something to me that finding how interesting life is here on earth and how all of the different nooks and crannies that it’s found its way into, all the times that it’s found a way, at all the different times in its history, that is the story that needs to be investigated, and we won’t be able to recognize the story of life on other worlds until we more deeply understand the story of life here on earth. And we’ve barely cracked the cover.
Dr. Pamela Gay: And it’s a really long book.
Fraser Cain: Yeah, it’s a really long book. Yeah, yeah. So, I think take a page from me on this one, be patient that the answer to this question isn’t going to be revealed instantaneously, that it’s gonna be like this gradual unfolding over decades as we gain more and more evidence to try to move towards what is one of the most important scientific questions we can possibly ask. So, it’s worth the wait.
Dr. Pamela Gay: And let’s just hope they find it while we’re still around. We’ll be bringing –
Fraser Cain: Yeah, exactly.
Dr. Pamela Gay: – it to you from our wheelchairs from the old folks’ home right here on Astronomy Cast.
Fraser Cain: Bit by bit. Yep, awesome. All right. Thank you, Pamela.
Dr. Pamela Gay: Thank you.
Fraser Cain: You got some names for us.
Dr. Pamela Gay: I do. So, as always, we are brought to you by you. It is your contributions through Patreon that allows us to keep our website going, to produce show notes, to produce transcripts, to pay our audio and video editors. There is an entire team that herd Fraser and I because we are not to be trusted. And it is that team that gets the show out the door every week. And allowing us to pay our team, is Abraham Cottrill, David Gates, Daniel Loosli, Gabriel Gauffin, Shannon Humber, Kimberly Rieck, The Air Major, Blixa the cat, Corinne Dmitruk, Glenn McDavid, Nial Bruce, Tim McMackin, Matthias Heyden, Dean, Naila, john ölseth, Antony Burgess, Steven Coffey, Bart Flaherty, planetar, Benjamin Davies, Janelle Duncan, Dean McDaniel, Kenneth Ryan, The Lonely Sand Person, Steven Shewalter, Andrew Stephenson, Don Mundis, Jen Greenwald, Rachel Fry, Anitusar, Lew Zealand, Paul D Disney, Chris Scherhaufer, Cooper, Karthik Venkatraman, Gregory Singleton, Phillip Walker, Elad Avron, Nate Detwiler, David, Matt Rucker, Mark Van Kooy, Allen M Price, and Rayvening. Thank you all.
Fraser Cain: Thanks everyone, and we’ll see you next week.
Dr. Pamela Gay: Bye-bye.
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