Planetary Radio • Sep 16, 2020

Have We Found Evidence of Life on Venus?

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On This Episode

Jane greaves

Jane Greaves

Astronomer and professor, Cardiff University

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Sara Seager

Astrophysicist and Planetary Scientist for Massachusetts Institute of Technology

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Casey Dreier

Chief of Space Policy for The Planetary Society

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Javier Peralta

Science team member, Akatsuki Venus orbiter

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

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Mat Kaplan

Senior Communications Adviser and former Host of Planetary Radio for The Planetary Society

An international team has detected phosphine gas in the clouds above Venus. Naturally-produced phosphine on Earth is created by anaerobic bacteria. We’ll listen to portions of the media briefing at which this result was announced. Then we’ll get perspective on the find from the Planetary Society’s Casey Dreier. Astrophysicist and Venus atmosphere expert Javier Peralta will share his reaction and a big find of his own on our nearest planetary neighbor.

Phosphine and Venus
Phosphine and Venus Artist's impression of Venus, with an inset showing a representation of the phosphine molecules detected in the high cloud decks.Image: ESO / M. Kornmesser / L. Calçada & NASA / JPL / Caltech
Venus' Upper Clouds
Venus' Upper Clouds Just after it entered orbit, Akatsuki’s LIR camera spotted an enormous stationary wave running completely across the globe from north to south on Venus. The camera sees heat emanating from Venus’ uppermost clouds, day or night.Image: JAXA/DARTS/ISAS
Atmospheric disruption on Venus
Atmospheric disruption on Venus An enormous atmospheric disruption in the clouds of Venus has been rapidly propagating at around 50 kilometers above the hidden surface.Image: J. Peralta / JAXA

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Jane Greaves: There is a chance that we have detected some kind of living organisms in the clouds of Venus.

Mat Kaplan: And there was yet another exciting discovery on Venus that we'll explore this week on Planetary Radio. Welcome, I'm Mat Kaplan of The Planetary Society, with more of the human adventure across our solar system and beyond. In a few moments, I'll share with you highlights of the September 14 media briefing that came from the Royal Astronomical Society.

Mat Kaplan: As space fans, you've probably heard that news. A gas that on Earth is only produced naturally by living organisms has apparently been found in the clouds above Venus. We'll follow these excerpts with our own, Casey Dreier, who has written a brilliant article putting this finding in context. Then, we'll welcome back astrophysicist and Venusian Atmospheric Expert, Javier Peralta. Javier is also excited about this discovery, but he led research that has revealed another amazing feature on Venus. Yeah, all that.

Mat Kaplan: And we'll still have this week's What's Up to look forward to. How can there be rust on the moon? Good question, but it has been found there. That's the lead story in the September 11 edition of The Downlink, The Planetary Society's weekly newsletter. You can also read about engineers finishing their work to reshape and resurface the big mirror for NASA's Nancy Grace Roman Space Telescope, the one previously known as WFIRST. And there's a terrific accomplishment by China's Chang'e-3 lander. It is still returning data from the moon seven years after its arrival. Scientist just published new findings about the layers of rock the probe is sitting on. As always, there's much more waiting for you at

Mat Kaplan: There were so much buzz in the days leading up to that RAS briefing on Monday, the 14th. Some of our space journalism colleagues who had been tipped off could barely contain themselves. The big announcement did not disappoint. I've selected a few clips from the virtual gathering, beginning with one from the leader of the international team that has made this discovery. Here is astronomer, planetary scientist, and professor at Cardiff University, Jane Greaves.

Jane Greaves: So what have we done? We're here to tell you, we have detected a rare gas called phosphine in the atmosphere of our neighbor planet, Venus. And the reason for our excitement is that phosphine gas on Earth is made by microorganisms that live in oxygen-free environments. And so there is a chance that we have detected some kind of living organisms in the clouds of Venus. So, yeah. I really am talking about Venus. As you probably know, the surface conditions there today are really hostile. Temperature is enough to melt our landers, for example, but it's thought that much earlier in Venus' history, the surface was much cooler and wetter and life could possibly have originated.

Jane Greaves: But conditions turned very hostile and there is a longstanding theory that some of the smallest forms of life, these microorganisms, might've been able to evolve upwards into the high clouds. So, conditions there are certainly not nice. They're extremely acidic and it's very windy. But on the other hand, if you're talking about 50 to 60 kilometers up, then the pressure is much like it is the surface of the Earth, and the temperature's quite nice, maybe up to about 30 centigrade, or 85 degrees Fahrenheit. So, it's been hypothesized that this is a living habitat today.

Jane Greaves: So I originated a project in 2016 to see if we could look, deliberately look for phosphine as a possible signature of living organisms in the high clouds of Venus. So we started with the James Clerk Maxwell Telescope in Hawaii, which is operated by the East Asia Observatory, and the U.K. is a long-term member of the other partners there. We also then went on to use the ALMA network of telescopes down in Chile, that's operated by Europe, North America, Japan, and other partners.

Jane Greaves: So what were we looking for? So, Venus is a natural source of radio waves. So, the wavelengths we were looking at were approximately one millimeter, and the radio waves originate kind of in the middle cloud layer. So, if you've got a phosphine molecule above that, it can absorb that radio light and take some of it away. And that actually happens at a really specific wavelength, which is to do with essentially the quantum rotation of the molecule. So they like to take that particular wavelength of radio light and remove it from the spectrum of Venus.

Jane Greaves: So what we get is not an image, as you might like or hope, we just get a graph. So, if there was no phosphine there but you spread the radio light out by wavelength, you'd get a flat red line here. But if you've got the phosphine present that sits very specific wavelength, which is 1.123 millimeters, the phosphine molecules will have removed the radio light and so you'll see a dip. The signal strengths will go down at exactly that point. And so our colleague, Hideo Sagawa from Kyoto Sangyo University in Japan, has done the calculations, which tell us for a certain number of phosphine molecules, how deep this dip will be.

Jane Greaves: Okay. So, let's cut to the chase. We have detected the phosphine, and this is the data from the telescopes. The first one we got is the discovery spectrum from the James Clerk Maxwell Telescope in 2017, you can see the stick in the middle. And then we were able to turn the full power of the many ALMA telescopes onto this in 2019, two years later, and we got a more detailed view of the planet spectrum. And then you can also again see, we have recovered this V-shaped dip at the right wavelength. So given we did this for two completely independent observatories, what we can say is, with very high confidence, we have detected the phosphine on Venus. And this is very exciting and was really quite unexpected.

Jane Greaves: Well, my colleague, Paul Rimmer at Cambridge University in the U.K., then used his atmospheric models and he tried what would happen if you put a source of phosphine in this computer-simulated atmosphere and let the chemistry of Venus work a way at it. And he found that the original idea was probably not crazy. So, the organisms wouldn't actually need to be super efficient. They could be producing at about 10% of the peak efficiency we see for real organisms known on Earth, and that would make the 20 parts per billion we see.

Mat Kaplan: Jane Greaves of Cardiff University, leader of the international team. Jane was followed by William Bains of MIT. He took us through the many other ways phosphine might have been generated that have nothing to do with life. The conclusion, none of these other pathways could explain the amount of gas that has been found. William then introduced past Planetary Radio guest, Sara Seager, his colleague at MIT.

Sara Seagar: We are not claiming we have found life on Venus. We are claiming a confident detection of phosphine gas, whose existence is a mystery. And I just want to reiterate what William said that phosphine can be produced by some processes on Venus, but only in such incredibly tiny amounts. It's not enough to explain our observation. So we're left with this other exciting and enticing possibility that perhaps there is some kind of life in Venus' clouds.

Sara Seagar: On Earth, phosphine is only associated with life, either bacteria and oxygen-free environments, or as produced by humans. So, you should know that phosphine exists in Jupiter's and Saturn's atmosphere, because those atmospheres are dominated by hydrogen gas and also importantly, have the right temperatures and pressures lower down to create phosphine.

Sara Seagar: We have to continue, we'd like to see our phosphine measurement confirmed at other wavelengths. Some team members have or are proposing to observe phosphine in the infrared with ground based observatories, though that will be challenging because of the weak spectral features of phosphine in the infrared. We hope our work will motivate space missions that go to Venus and directly measure gases in the atmosphere.

Sara Seagar: People have speculated on life in the Venus atmosphere for decades, for over 50 years, actually, starting with Carl Sagan. And perhaps life originated when Venus was cooler with liquid water oceans. But as Venus heated up and underwent its catastrophic runaway greenhouse, the oceans evaporated and the surface became so hot that any life would have been killed. But life in the clouds, assuming life had been able to migrate to the clouds and live there, that life would have survived.

Sara Seagar: By the way, Earth has life in the clouds. Bacteria are upswept from the surface and they live freely, floating in the clouds or in liquid water droplets. And life stays up there only for about a week or so. Sometimes, it's transported across continents before being rained back down. Now, Earth's clouds don't last very long. But on Venus, the clouds are permanent. They cover the entire planet and they are very big in vertical extent. We argue that any life on Venus, like bacteria type particles, would have to reside inside the protective hydro sulfuric acid, even though the acid itself is incredibly harsh.

Sara Seagar: As humans, we have wondered about life beyond Earth for thousands of years. We now know that nearly all stars have planets and astronomers have found thousands of exoplanets orbiting nearby stars. We know that rocky planets are common. A generation of astronomers is now working to enable future telescopes, observations and theory, to be able to find signs of life on exoplanets far away by looking for gases in the atmosphere that don't belong. Our team has also studied phosphine gas, but it's very different than the Venus case because we would need a lot of observation time or a lot more phosphine, or both.

Sara Seagar: In our solar system, closer to home in our solar system, there were growing number of bodies of astrobiological interest for the search of life. We have NASA's Perseverance rover on its way to Mars to search for signs of ancient life. Jupiter's icy moon, Europa, is one of our best targets because of its liquid water oceans beneath its icy shell. Saturn's moon, Enceladus, like Europa, has water geysers that people match in [inaudible 00:10:33] Spacecraft 2 to fly through and look for organics. Saturn's moon, Titan, is actually even more interesting with liquid. Liquid is needed for all life, as we know it. But Titan has liquid hydrocarbon lakes of ethane and methane

Sara Seagar: Now, we have, by our phosphine gas discovery, we have raised Venus higher up on that ladder of interesting targets. And we hope that our discovery motivates focused space missions to go to Venus to look for other gases, more gases, signs of life, and even life itself.

Mat Kaplan: Reporters were then given the chance to ask questions of the scientist, mine won't surprise anyone who is familiar with The Planetary Society.

Mat Kaplan: Congratulations on, first of all, this marvelous discovery. This question is really for any of you or all of you. You talk about how you hope that this result will increase the interest in returning a mission to Venus. What sort of mission would you like to see that would be best capable of investigating further this layer of the atmosphere where this activity may be taking place?

Sara Seagar: Well, as you may know, there has been a lot of mission planning and mission thinking for many years, actually. And right now, there are two missions under the NASA Discovery class, they're under a phase A competition right now. So, we'd like to see really any kind of mission go back to Venus, something that's capable of measuring gases in the atmosphere, something that has a so called mass spectrometer that can identify larger complex molecules that could only be associated with life. We have a long list of things we'd like, actually. Perhaps, ultimately, we could send a microscope. This is tougher, actually, because cells are spherical or they may be confounded with hazes and other aerosols and atmosphere particles. So, it's like the missions that are being planned but focused on signs of life detection and life detection itself.

Jane Greaves: Just to add to that, I think it is very exciting. Japan have got an orbiter at the moment. India have plans to launch one. Europe has longer term plans. We're really hoping somebody or maybe private space industry, somebody might take this up.

Mat Kaplan: Would you like to see a balloon, as has been proposed in the past, that might actually reach in to this layer of the atmosphere?

Sara Seagar: A balloon is certainly the best way. And the Vega balloons did just that. They lasted a couple days. They were tens of kilograms, low tens of kilograms. And that's the kind of thing we'd like to see happen again, perhaps a super version of those that instead of lasting two days, could last weeks, months, even a couple years.

Mat Kaplan: Astronomer Sara Seager of MIT. For additional context, we turn to my Planetary Society colleague, Casey Dreier. Casey is the Society's Chief Advocate and Senior Space Policy Adviser, but he's also as big a space geek as any of us.

Mat Kaplan: Casey, thanks for jumping in on this literally at the last moment. Also, for very quickly turning out this terrific article, Did Scientists Just Find Life on Venus, Here's How to Interpret the Phosphine Discovery, which was published on our site on September 14th, just minutes, moments after the announcement was made. Before we get into your analysis, your thoughtful consideration of this, do you agree that this is something we can be excited about?

Casey Dreier: Mat, there's, occasionally, every now and then, times where my old grizzled space advocate heart goes aflutter at new information that reminds me in a sense why we do this, why we explore space, why we look outwards, because you just don't know what you're going to find sometimes.

Casey Dreier: Our boss, Bill, talks about the joy of discovery. I don't think, and I hope, maybe I hope that the case, that no scientist isn't feeling a little joy today at the idea, the possibility that we may have discovered something completely profound. This is the first step in a longer process. This is a data point in the support of a hypothesis, but it's not the end all and be all of this. But it's okay to be excited about that. That's why we do this. So, yes. It's an exciting announcement today.

Mat Kaplan: And you were the one who pointed me to the tweet from Jim Bridenstine, the Administrator of NASA, "Life on Venus? The discovery of phosphine, a byproduct of anerobic biology is the most significant development yet in building the case for life off Earth. About 10 years ago, NASA discovered microbial life at 120,000 feet in Earth's upper atmosphere. It's time to prioritize Venus." That last sentence is maybe the most significant to me. Do you agree that this strengthens the argument for more missions?

Casey Dreier: It absolutely does. I was thinking today, this could be a very similar moment to the ALH 84001 meteorite that had hints, again, similar to this hints of Martian life, but turned out to be disputed and now accepted. But we got the last 25 years of Mars exploration at NASA kind of from that discovery. In a similar way, when they discovered plumes of Europa that a spacecraft could fly through to help answer the life question there, that helped push the Europa Clipper over the edge. And this is the exact type of moment where a new discovery helps push a potential mission into reality.

Casey Dreier: And there are two missions right now being considered under the small program line on planetary science, DAVINCI and VERITAS, that wouldn't necessarily answer this question but maybe they could be adapted to do so. The discovery program line was designed to be responsive to new discoveries. And yes, I think one of the biggest results from this, regardless of the outcome of this claim, is seeing a renewed push to further understand and characterize our nearest neighbor to Earth.

Mat Kaplan: Nevertheless, in the words of distinguished Co-Founder of The Planetary Society, extraordinary claims require extraordinary evidence. And you lay out some of what needs to happen next, beginning with we need independent confirmation.

Casey Dreier: That's right. And I wrote this article for people like me, I think most of us who are not professional scientists, who maybe have some scientific background or just like to follow science, how do we evaluate claims like this as we're not in the field? And there's a number of things that we can do just in general when big claims like this are made to kind of evaluate the claim, how seriously to take it, and then again, where do we kind of stand and what needs to happen next. And so, yes, scientific process, if this is a real signal, then an independent team with a different type of equipment looking for the same signal should see it, right? That's the first thing that needs to happen, that'll be at the first, I'm certain.

Casey Dreier: A number of applications are being made to telescopes around the world right now and if they see that too using their own methods for data analysis and modeling to verify that signal, that needs to happen in order to say this is the real thing and not some cork of the model that they're using or a subtle flaw in their data analysis. So again, independent verification, that's a key process of science that'll be happening here in the next few months to years.

Mat Kaplan: And to be fair, you mentioned, it's right in the paper, published by these scientists. There may be other explanations or maybe, they made an error of some kind, then you make the point, just as was made with ALH 84001, bio signatures do not equal life.

Casey Dreier: That's true. And again, the only things that we know for sure, and to really clarify this, the claims made by the scientists in this paper are that we think we have detected a phosphine signature in the atmosphere of Venus and that we cannot explain it through the natural processes as we understand them now on Venus. That's the only claims being made here, right? So, that leaves us with a potential couple of outcomes. One, as we've already talked about, maybe there's a biological source of this chemical, or, as they point out, maybe there's another type of chemical reaction in this complex system of Venus' atmosphere that produces phosphine, and we just don't understand Venus that well.

Casey Dreier: Most other planets outside of Earth have not been explored that much, even Mars. We have very simplified models. It's because we do not have that much data. They also even pose another one, which is there could be another chemical that is unknown to us or some combination of chemicals that gives off a signal that's very similar to that of phosphine in this detection arena of sub millimeter astronomy. And it would be almost like a mimic signal and they would be getting confused at the scales they're looking at and see it as phosphines out of something else. That's less likely but it's still a possibility, and there are ways that they can do more observations to try to eliminate these other explanations. And that is the process of science. Now we get to work as a society, as a scientific society, to test this hypothesis from a number of different ways.

Mat Kaplan: And even the discovery of some other mechanism creating this phosphine or something that mimics it will still be a terrific product of good science. Casey, great job. Thank you for joining this important discussion. I join you in that excitement as well. But be careful what you read online, everybody. And something you should listen to online is the most recent Space Policy Edition of Planetary Radio, Casey's conversation with Scott Pace, the day-to-day leader of the National Space Council here in the United States, which is a great conversation, Casey, I'll say it again. Thank you again for doing this today too.

Casey Dreier: Oh, happy to talk about this, Mat. This is a privilege to be able to focus on this as the news in the world today. This is what I would prefer to be talking about and thinking about every day. It's like, oh no, another bio signature detection. Let's unpack this.

Mat Kaplan: That's Casey Dreier of The Planetary Society's Chief Advocate and Senior Space Policy Adviser. There's much more waiting for you on this week's show page at, including a link to that complete briefing that originated from the Royal Astronomical Society. When we return, I'll talk with Venusian Atmospheric Expert, Javier Peralta. Here's a message from a company that is helping us bring you Planetary Radio.

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Mat Kaplan: Welcome back to our extended coverage of the big news from Earth's solar system twin, Venus. Javier Peralta last joined us in November of 2019, that was shortly after he pinned a terrific article in the September Equinox Edition of The Planetary Report. He shared what we are learning about second rock's amazing and still mysterious atmosphere, especially from the Japanese space agency's Akatsuki. Javier is still a member of the orbiter science team, but he is back home in Spain after serving several years in Japan. I'm embarrassed to admit that I had some trouble with my microphone during our conversation, but no, I think you'll manage.

Mat Kaplan: Let's talk about your paper, first of all, which was published last May, actually, in the geophysical research letters of the American Geophysical Union, and it's titled A Long Lived Sharp Disruption on the Lower Clouds of Venus. Really though, what's wonderful about this is when you see the movies and you see this feature that looks like a line going across Venus, or at least in the atmosphere of Venus, it's really a pretty amazing thing to look at, and apparently, it's been there for many, many years?

Javier Peralta: Yes. Oh, that was a surprise. But everything depends on the point of view because when we first studied for several years the atmosphere of Venus with Venus Express, our spacecraft at polar orbit, we observed very well the polar region, the southern hemisphere out of the polar region of the north, but when the spacecraft passed over the equator, the velocity was very fast and we didn't have proper observations for watching what was happening at lower latitudes. The surprise was when we found this structure, this pattern in the clouds moving so fast, faster than the winds, that the winds of the super-rotation are already fast on Venus.

Javier Peralta: The other surprise came when we decided to check in the past, in past observations of the lower clouds in the mid of the '80s when they discovered this spectra windows for observing these deeper clouds and we have said that this structure was there. And then we go through other observations other years, and it was still there. So it was a surprise because we have been missed something that seems to have the impression of Venus several decades.

Mat Kaplan: It is a striking thing to see. I'm looking at the video in one of the articles that covered this find, and you are the lead author of this paper, I think I neglected to say that. It just looks like something... I mean, it reminds me of those things that we have seen on Jupiter, like the great red spot, which seems so persistent and so dramatic in their appearance on the planet. I mean, this is not a roughly circular red spot, it's a long line. But what in the world could account for something like this being so persistent in its atmosphere, which is incredibly dynamic?

Javier Peralta: Yeah. We had a lot of problems for interpreting this phenomenon. We don't know what to do while we're observing. One of the main hypothesis is that we have discovered a new type of wave, what we call a Kelvin wave, moving into the west, faster than the winds. But in the paper, we left a cleared idea that it is open to new interpretations. It was difficult to interpret this phenomenon because we cannot have a proper insight about how this structure is affecting other physical parameters of the atmosphere. What we see is that it is disturbing strongly the clouds, the deeper clouds of Venus. But the effect of disturbance of the clouds is not clear in terms of how it affects, for example, the aerosols, the temperature, the atmospheric density.

Javier Peralta: We suspect this structure is separating two big regions of the clouds. One on the east side, that is much denser, and it blocks the thermal emission from the surface. And on the other side, on the west side, it is less dense clouds, more transparent that allows to pass more heat from below. We also know that in some way, it is stimulating some kind of disabilities in the atmosphere because of this disruption. We see associated formation of, for example, vortices, that was also a big surprise to find on Venus.

Mat Kaplan: Yes, I think I could see some of those vortices in this animation that I'm watching. And we'll try to put this on this week's show page as well at How deep into Venus' atmosphere, or maybe I should say, how high above the surface is this feature?

Javier Peralta: It is between 38 kilometers, and let's say, 55 kilometers for the lower clouds, okay? On Venus, we have three levels of clouds, three different layers. The lower clouds, the middle clouds and the upper clouds. What we know also, thanks to Akatsuki, is that sometimes, we can see this structure also moving in the middle clouds that are located about 10 kilometers above these lower clouds.

Mat Kaplan: This feature crosses into that range of the Venusian atmosphere where the phosphine has been found. I'll come back to that. You mentioned super-rotation, which is the reference to the fact that Venus' clouds, its atmosphere, is rotating faster than the planet is. Is this feature that you found possibly related to that super-rotation? Is it somehow responsible for it?

Javier Peralta: It depends on what we are observing, of course. In case that this structure, for example, this wave, it might help to explain a new way of feeding the super-rotation from the deep atmosphere upwards. There was a recent paper also published the date close to ours in science with Akatsuki results. It was a paper by Takeshi Horinouchi. He examined the role of the solar tides to excite and to keep the super-rotation of Venus. In this case, we are talking about the source of energy for the motions of the atmosphere. That depends on the heating of the sun over the upper clouds, okay? So we are talking about the source of oxidation for the super-rotation that happens in the upper clouds and maybe a part in the middle clouds, but not coming from the deep atmosphere, okay, or from the surface.

Javier Peralta: For us, the lower clouds has been a big mystery because what we observed in the lower clouds did not correspond to what we observed on the upper clouds. For example, the lack of big waves, of giant waves. We observed also with Akatsuki for the first time is touching on the waves that were created on the surface by interaction of the slow winds, we saw came from the surface and then manifest in the upper clouds. But curiously, when we observe these lower clouds on the night sight, we don't observe this stationary wind, what is really striking and really weird.

Javier Peralta: For a long time, we didn't find big waves or we didn't find the waves that were propagating from below to the upper clouds in this intervening level of the atmosphere. We still don't understand why. So for us, it's a big surprise to find what can be a wave manifesting in these lower clouds for the first time. The idea that this is very interesting for explaining the super-rotation has to be with one of the discoveries of the pioneer Venus mission in the '80s where some of the probes went into the atmosphere, falling onto the surface. They were measuring the winds and [inaudible 00:30:56] Venus measurements, due to these entry probes, they have the chance of measuring in situ the winds of Venus.

Javier Peralta: And they discovered that most of the angular momentum, most of the energy of this super-rotation, if start not in the clouds but very deep in the atmosphere, at about 20 kilometers. This range of 20 kilometers above the surface is where we have the major density of angular momentum in the atmosphere. According to our simulations, what we are observing, this discontinuity seems to be a wave that is generating in that level, and then coming up to the clouds, and then, dissipating before arriving at the upper clouds, and then, transporting this energy from the deep atmosphere to the upper clouds.

Mat Kaplan: Fascinating. And point out that we still have a great deal to learn about Venus and the sky above its surface. Let me turn now to this announcement this morning from this international team of this discovery of the phosphine, which we've already heard a little bit about. I'm just curious, you've read a little bit about this as well, what do you think of this find of phosphine, which just happens to be in this middle layer of clouds at Venus?

Javier Peralta: This is fascinating because we have a very long time discussions on whether there is life on Venus or not. Some of our colleagues have the hypothesis that the reason why we cannot explain the real nature of the unknown absorber, you know that on Venus, on the upper clouds, we observed some markings and ultraviolet wavelengths, something that is absorbing the ultraviolet solar radiation, and we don't know. For decades, we have not known what is the absorber that is...

Mat Kaplan: I remember. Yeah, we talked about this previously and it's one of those mysteries.

Javier Peralta: Yes. Some of the hypothesis for this absorber were bacteria. I remember one of our colleagues, [inaudible 00:32:58], also published a paper a couple of years ago, revising the idea that some of the bacteria that can be studied here on the Earth have the property precisely to absorbing ultraviolet wavelengths. And why not? Maybe we have bacteria floating on the clouds. At the time, of course, it's kind of challenging hypothesis, difficult to confirm. But now, we found this really, really exciting work today, this morning. We are really excited because even though this cannot be yet considered definitive confirmation of life yet, but it opens the door again for trying to find out if there are bacteria that float within the clouds of Venus.

Javier Peralta: And I am pretty sure that because of this work, now, many people are going to try to make new observations, revising data from the spacecraft, and mainly because [inaudible 00:33:52], we have stored data where we have some an infrared sun absorption bands from the phosphine. I'm pretty sure that this discovery is going to stimulate a lot of work, additional works to try to confirm this result because it could be amazing to discover that the life in our solar system was precisely in the place where we didn't expect at all.

Mat Kaplan: That's so true. I'm going to bet also that just as we heard from the scientists involved in this newest research that you also see this as an even better argument or an additional argument for more missions to Venus, more planetary science missions.

Javier Peralta: Yeah. Some colleagues of mine that are working with Mars, they are telling, "Oh, you're making this up because you want to steal mission from Mars to Venus." Of course, I have the hopes that this will stimulate to some new spacecraft to Venus to make new observations. And of course, ground based observations, that will be the first step, of course. And I think, I read somewhere that the original authors of this paper, they wanted to try also some additional independent observation with SOFIA. They didn't have the chance, somebody else will have, I guess. But now is the time of course to try to look at Venus and try to confirm this amazing or promising result.

Mat Kaplan: SOFIA, of course, that wonderful infrared telescope mounted in the 747 airplane that I've actually flown on and covered that as part of this show. So, we still have a lot to learn but this certainly has been exciting news, both your own research and what we learned just this morning.

Javier Peralta: I am really excited also because the India mission that will be launched hopefully maybe in three or four years, I don't know when, they might include in their scientific goals the confirmation about the phosphine discovery.

Mat Kaplan: Excellent. Gosh, I sure hope that they can include that increments that will help them study that further. Javier, thank you again. As I said, what a wonderful coincidence that we were already going to be talking today. Congratulations on your own work, and thank you for adding to this exciting news that we learned about just this morning.

Javier Peralta: Oh, thanks to you. And I am really excited, I want to read more about this paper. And you can imagine how light on we are now in the scientific community of studying Venus.

Mat Kaplan: And that is exactly how we would like it to be at The Planetary Society. Thanks again.

Javier Peralta: Thank you so much.

Mat Kaplan: Astrophysicist and member of the Akatsuki Venus orbiter science team, Javier Peralta. Bruce Betts and What's Up are next.

Bill Nye: Perseverance is on its way to Mars. Bill Nye, the Planetary guy here. I'll be watching when this new Mars rover arrives at the red planet on 18 February 2021. Would you and a friend like to join me? We'll put you up in a four-star hotel, enjoy a great lunch conversation about space exploration and share our excitement as the rover descends the Martian surface. Then we'll send you home with a Mars MOVA Globe signed by me. Visit to enter and support The Planetary Society. That's I look forward to welcoming you as we return to Mars.

Mat Kaplan: Time for What's Up on Planetary Radio. This is... I'm distracted because I'm looking at pictures. We're doing live video as we do What's Up for the first time. I'm saying that even though I don't plan to share this with all of you, but we're testing a new version of our software of choice, [inaudible 00:37:36], and it's a beta and it offers video. And I'm going to be using this for some other stuff...

Bruce Betts: watch me sneeze.

Mat Kaplan: Wait. You're going to sneeze?

Bruce Betts: Yeah. Was that cool?

Mat Kaplan: Oh, that was outstanding.

Bruce Betts: It's all smoky over here.

Mat Kaplan: Oh, yeah. You are smack dab in the middle of the smoke zone near Pasadena, aren't you? I am so sorry about that. The air here has improved quite a bit, but I hear it's not great by you.

Bruce Betts: No, it is not. I mean, it could be worse, but it's pretty nasty.

Mat Kaplan: I hope that improves very soon. Let's look to the sky, that you may not be able to see very well through the smoke, can you tell the rest of us what's up?

Bruce Betts: Hi. If you don't have a bunch of smoke, then there are planets that are very easy to see. We've got Jupiter and Saturn still in the evening sky in the south. Looking super bright, Jupiter in particular. Saturn, dimmer, but still looking bright over to Jupiter's left. And the big star for the next few weeks is Mars coming up in the early evening in the east, approaching its closest approach to Earth this time around, which will be on October 6th. It will be an opposition, or opposite side of the Earth from the sun on October 13th. So, it's bright. It's almost as bright as Jupiter right now, will get as bright as Jupiter as it comes to a closest approach. And it's a spectacular evening sight in the east, and then moving over to the south. In the pre-dawn, Venus still just looking Venusy, all super bright and over in the east in the pre-dawn.

Mat Kaplan: Mars, not to be confused with an actual star.

Bruce Betts: Please continue. Mars? No, it's a planet. I know stuff. Onto this weekend's space history. It was 2014 that the NASA spacecraft, Maven, went in to orbit around Mars, studying its atmosphere, particularly upper outer atmosphere, and it's still working and partying in Mars' orbit.

Mat Kaplan: Another long lived, that one up there.

Bruce Betts: We move on to Random Space Fact.

Mat Kaplan: Oh, the video really magnifies the magnificence of that.

Bruce Betts: The glory. So a short one here today. It's all Venusy. The surface gravity of Venus is about 91% the surface gravity of Earth. So if you're looking to drop some weight without dropping mass, it's not the ideal place. But if you're looking to just take a little off, you might consider being a surface instead of liposuction, although you will get cooked. So, never mind. Bad idea.

Mat Kaplan: I've noticed that when you burn stuff, it gets a lot lighter.

Bruce Betts: That's true. You would be a desiccated version of yourself. Yummy. Okay. Let's move on to the trivia contest, and I asked you what was the only spacecraft to launch with solar system escape velocity. So when it launched, didn't have enough velocity that it would leave the solar system and never come back, unless aliens brought it back in a Star Trek movie. [inaudible 00:40:57], Mat.

Mat Kaplan: I'm just still thinking of V'ger, I guess. We got a huge response to this, surprisingly large, and that's always very gratifying. And thank you to all of you who talked about how much you're enjoying the show in your little comment field in the entry form. I'm going to let Dave Fairchild, the Poet Laureate, answer this for us. He has his usual rhyming response, but it ends with something really clever. "When New Horizons was launched from the pad, it flew in an Atlas V ship, a common core booster, they strapped on some more to give it the gravity slip. It sped by the moon in nine hours or so, its rocket fuel totally burned. Velocity set for a solar escape and leaving the sun in its stern."

Bruce Betts: Ah.

Mat Kaplan: That one's for you I guess, Alan. Well, to tip him off. Yeah, New Horizons, right?

Bruce Betts: New Horizons, indeed. Pioneer-10 and 11 of Voyager 1 and 2, also with solar system escape velocity, but were not launched with that. They picked up extra velocity from gravity assist, tested New Horizons, but less so. And so they're all heading away, but only New Horizons flew away without requiring any gravity assist. You never come back unless the aliens build a giant robotic structure to send... spoiler alert. Never mind.

Mat Kaplan: I love that movie. Here's our winner. And this is pretty cool. Longtime listener, friend of the show, past guest on the show, but a first time listener as chosen by It's Jon Cowart in Florida. Jon who is a leader of the now successful commercial crew program at NASA. He has moved to the human spaceflight program at Aerospace Corporation. He manages the human spaceflight program. And now, I'm sure this will be his crowning glory, the thing he will be most proud of in his life. He has won the contest and will receive Sarah Stewart Johnson's wonderful book, Sirens of Mars, which I still recommend very highly. It's quite a wonderful tribute to the red planet, the one that's a star but not a real star.

Mat Kaplan: He said, "Yeah, it's New Horizons 36,000 miles per hour, relative to Earth, but sun escape velocity, 94,175 miles per hour, with apologies to listeners who prefer KM per second, when New Horizons left Earth, it's popular to say it was going at 36,000. I'm still reading Jon's response here. But if you add in Earth's sun relative velocity of 67,108, you've got 103,108 miles per hour." He adds, "Apologies to orbital mechanics enthusiasts and Newtonian physicists everywhere for my gross approximating." Congrats, Jon.

Bruce Betts: Yeah. No, he makes an important point that it only has the true escape velocity from the solar system by taking advantage of leaping out with Earth's velocity around the sun.

Mat Kaplan: Several entrants, including Laura Dot, mentioned the Parker Solar Probe has become the fastest spacecraft, but Laura knew it didn't start out the fastest, which is what you were looking for, of course.

Bruce Betts: I also want to make a note that it's fastest because it's headed and being pulled in by the gravity of the sun and not being slowed down by the gravity of the sun as... I mean, it is turned part of its orbit, but not way out. All these spacecraft just keep getting slowed down more and more as they're moving away from us.

Mat Kaplan: So, I got more. [inaudible 00:44:44] in Ontario likes these speedy spacecraft, but he prefers Planetary Radio's waves traveling at the speed of light every Wednesday.

Bruce Betts: That's a really good point.

Mat Kaplan: Mark Dunning in Florida, "New Horizons continues the delivery, found footage of the launch and with those five strap-on solid rocket boosters," he said, "that thing all but leapt off the pad." Ian Gilroy, Australia, "At that speed, I could get from Sydney to Pasadena in under 15 minutes. Put the coffee on, Mat."

Bruce Betts: Nice.

Mat Kaplan: You can try our wonderful coffee machine that the boss, Bill Nye, mentioned last week. But you won't have much company, I'm afraid. Stephanie Delgado in Arizona, "14 years and more of passion, beauty and joy and inspiration for the entire planet. Thank you, New Horizons." It was launched in 2006, early 2006. Finally, another poem, which, you're a big fan of the TV show, Psych, right?

Bruce Betts: Oh, yeah, one of my favorites. Yup.

Mat Kaplan: I don't blame you because it's a great premise. I've watched a couple of episodes. Don't know why I never became a regular with it, but I know you are. So this from Jean Lewin, "A hasty exit from planet Earth, a launch that set a pace, achieving escape velocity to the far reaches of space, heading for a planet, then New Horizons stayed its course, arriving to find that its destination now is classified an icy dwarf. But Burton Guster utilizes this Kuiper belt line, 'Have you heard about Pluto?' As his go-to pickup line."

Bruce Betts: Heard about Pluto? That's messed up.

Mat Kaplan: So it's real?

Bruce Betts: Oh, yeah. I mean, yes. I mean, it's a TV show, but yes, that's an ongoing joke with Gus.

Mat Kaplan: We are ready to move on.

Bruce Betts: Who is the only man that has a feature on Venus named after him? That's it. Go to

Mat Kaplan: I'm going to guess Bruce Betts.

Bruce Betts: If there were justice in the world. Well, actually, I'm kind of glad because you almost, you pretty much have to be dead to have a feature named after you, so I'm willing to wait.

Mat Kaplan: Yeah. I think that's a great idea. Wait a long time. You've got until the 23rd, September 23rd at 8:00 AM Pacific time, to get us the answer to this one. And it is proven very popular, not surprising, as it has been in the past, so, we offer our winner, once again, a Planetary Radio Kick Asteroid! rubber asteroid. It could be yours. Got to enter though to win. And we're done.

Bruce Betts: All right, everybody. Go out there and look up the night sky and think about what I'm seeing, Mat Kaplan on video. Thank you, and good night.

Mat Kaplan: Yeah, on my Planetary Society eclipse t-shirt. I didn't think anybody'd see this. What have you got?

Bruce Betts: I got [inaudible 00:47:39].

Mat Kaplan: I think the shirt muffled your voice there. Must be good insulator.

Bruce Betts: [inaudible 00:47:44].

Mat Kaplan: He's the Chief Scientist for The Planetary Society and the LightSail Program Manager. He joins us every week here for What's Up.

Mat Kaplan: Planetary Radio is produced by The Planetary Society in Pasadena, California, and is made possible by its members who can't wait to find life elsewhere in the universe. You can join our quest at

Mat Kaplan: Mark Hilverda is our Associate Producer. Josh Doyle composed our theme, which is arranged and performed by Peter Schlosser. Ad astra.