Planetary Radio • Oct 21, 2020

Sampling an Asteroid and Searching for Life in Venus' Clouds

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20140914 Dante Lauretta thumbnail

Dante Lauretta

OSIRIS-REx Principal Investigator for University of Arizona

Jane greaves

Jane Greaves

Astronomer and professor, Cardiff University

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

Kaplan mat headshot 0114a print

Mat Kaplan

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

OSIRIS-REx has done it! We have special coverage of the spacecraft’s successful collection of a sample from asteroid Bennu. Then we talk with Jane Greaves, leader of the team that found evidence of phosphine gas in the atmosphere of Venus. Has this put us on the road to discovery of life above that hellish world? Bruce Betts and Mat Kaplan offer a copy of Beyond Earth’s Edge: The Poetry of Spaceflight in the new space trivia contest.

Asteroid Bennu
Asteroid Bennu This mosaic of asteroid Bennu was created using 12 separate images captured in December 2018 by NASA's OSIRIS-REx spacecraft.Image: NASA/Goddard/University of Arizona/Edited by The Planetary Society
OSIRIS-REx Sample Collection Location
OSIRIS-REx Sample Collection Location This mosaic of the primary sample collection site for NASA's OSIRIS-REx mission was created with 345 images captured by the spacecraft on 3 March 2020. OSIRIS-REx was 250 meters (820 feet) above the surface at the time. The specific collection site is the relatively rock-free area in the middle. The boulder in the upper-right is 13 meters (45 feet) wide on its longest axis.Image: NASA/Goddard/University of Arizona
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

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Trivia Contest

This week's prizes:

Beyond Earth’s Edge: The Poetry of Spaceflight, edited by Julie Swarstad Johnson and Christopher Cokinos.

This week's question:

How many robotic spacecraft have returned samples from the Moon and beyond?

To submit your answer:

Complete the contest entry form at or write to us at [email protected] no later than Wednesday, October 28th at 8am Pacific Time. Be sure to include your name and mailing address.

Last week's question:

Who was the original principal investigator on the OSIRIS-REx mission?


The winner will be revealed next week.

Question from the 7 October space trivia contest:

To celebrate its 40th anniversary, how many 25-meter dishes make up the Very Large Array in New Mexico? There could be 2 possible answers, either of which will be accepted.


The Jansky Very Large Array of radio telescopes consists of 28 25-meter dishes, with one of them usually undergoing maintenance.


Mat Kaplan: OSIRIS-REx says, "TAG. You're it." And the search for life above Venus this week on Planetary Radio.

Mat Kaplan: Welcome, I'm Mat Kaplan of the Planetary Society with more of the human adventure across our solar system and beyond. TAG, touch and go, that's what just happened at an asteroid. We have breaking news from Planetary Society editorial director, Jason Davis, about what the OSIRIS-REx spacecraft appears to have accomplished at asteroid Bennu. You'll also hear Dante Lauretta, the mission's principal investigator at the breathless moment of contact. Meanwhile, over at Venus, let's not jump to conclusions, astrophysicist Jane Greaves is the first to say we are a long way from determining if living organisms are responsible for the phosphine gas her team has discovered in the Venusian atmosphere. Stay with us for a fascinating and very enjoyable conversation with Jane.

Mat Kaplan: Jason, welcome back. We waited until nearly our production deadline, so we could include your report in this week's episode. Tell us what happened just minutes ago, more than 320 million kilometers from Earth.

Jason Davis: Yeah, hot off the press here. NASA's OSIRIS-REx spacecraft just touched down on asteroid Bennu. It's a near-earth asteroid, it launched in 2016. Took about four years to get there and survey the asteroid, find a place to land, and finally the big moment just happened where it touched down, fired this little bottle of gas into the surface that hopefully collected some good sample material that will eventually be brought back to Earth. So right now we know the spacecraft is safe and it did its job successfully. We'll have to wait to see exactly how much it got.

Mat Kaplan: We'll come back in a moment, but here is OSIRIS-REx principal investigator, Dante Lauretta, at the moment of contact with Bennu. He's at Lockheed Martin, I think, in Colorado, where they were controlling the mission, and then a few moments later as the spacecraft lifted off immediately after collecting the sample.

Dante Lauretta: O-REx has descended below the five meter mark. The hazard mass is go for TAG. Contact expected in 50 seconds.

Speaker 4: We're going in.

Speaker 5: We're going in.

Speaker 4: We're going in.

Dante Lauretta: Touchdown declared.

Speaker 6: All right.

Dante Lauretta: Sampling is in progress. O-REx MSA on O-REx off. Sample collection is complete. And the back away burn has executed.

Female: Backing away from the asteroid.

Male: All right, we're on our way back.

Mat Kaplan: Here's a program note, Dante will be my guest next week, the October 28th episode of Planetary Radio. Jason, what made this encounter so challenging for OSIRIS-REx and the team behind it?

Jason Davis: They designed the spacecraft to be able to sample from a relatively sandy surface. They anticipated different types of material on the surface, or least they weren't sure what they'd see. But they figured they have at least a lot of room to work with and some pretty fine-grain material. When they got to Bennu, it turned out the asteroid was rocky, much rockier than they expected. They had to narrow down, essentially, the size of the sample collection site.

Jason Davis: It took them a while to survey the asteroid, and carefully select a place they thought they could land. Luckily the spacecraft turned out to be performing exceptionally well at Bennu. It was much more accurate in its navigation than they'd even hoped. So they were able to select a much smaller sample site, and they found this area that does appear to have some fine-grain materials in it that they can collect. So hopefully they got some.

Mat Kaplan: Absolutely fantastic performance. Of course, everybody wants to know, where's the pictures? Where are the pictures? But I guess it may be a little while before we see those?

Jason Davis: Yeah, we're not sure whether we're going to see any later today or by the time this broadcasts airs tomorrow. But yeah, the spacecraft has to turn its high-gain antenna away from Earth to get into position to collect a sample, so the data rate just slows to a trickle as it's moving into the surface. They're only getting very basic telemetry data from the spacecraft. So they can tell, in kind of text form, what its doing, but beyond that they can't see anything. So we'll see those pictures very soon, hopefully.

Mat Kaplan: Can't wait, also for confirmation that there actually are little bits of Bennu inside that container that has just departed from the asteroid surface. Thank you, Jason, glad we could work this in. I look forward to talking again.

Jason Davis: Yeah, sounds good.

Mat Kaplan: Let's here from Dante Lauretta one more time before we go back to our regular programming with highlights of the most recent edition of the Downlink, and my conversation with Jane Greaves. Here is Dante summing up moments after the encounter.

Dante Lauretta: Little overwhelmed right now, I'm sure I'll have to say, it's been a pretty intense several minutes here. I can tell you that everything went just exactly perfect. Which is kind of the hallmark of this team, we have consistently beaten expectations over and over again. We have overcome the amazing challenges that this asteroid has thrown at us. And the spacecraft appears to have operated flawlessly. We made it down to the asteroid's surface. We were in contact, the gas bottles fired. We don't know how long we were in contact with yet, that's some reconstructed information that we're going to have to put together over the next few hours as the data come in. We backed away successfully from the asteroid's surface. The team is exuberant back there. Emotions are high, everybody is really proud, and we have some work to do.

Mat Kaplan: That was Dante Lauretta, principal investigator for OSIRIS-REx mission that appears to have successfully made its first collection of material from asteroid Bennu. And speaking of Bennu, a great image of that lonely space rock tops the October 16 edition of the Downlink. Looking at its boulder covered surface makes me even more impressed by what OSIRIS-REx has accomplished. Dante Lauretta and his team had already announced discovery of carbon containing organics scattered across the asteroid.

Mat Kaplan: In other news, Europe and Japan's BepiColombo probe has made its first close flyby of Venus. It will do this again before five flybys of Mercury, also that it can slow down enough to enter orbit around that small world in 2025. And three astronauts arrived at the International Space Station last week. Their Soyuz capsule had lifted off from Russia's spaceport just three hours earlier. Aboard was Kate Rubins, who is likely to be the last American to reach the ISS in a Soyuz before commercial flights by Crew Dragon spacecraft begin later this year. Much more is waiting for you at

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

Mat Kaplan: That is how we began our September 16th episode, astrophysicist Jane Greaves of Cardiff University led the team that had just announced its discovery of phosphine gas in the Venusian atmosphere. We shared excerpts from the Royal Astronomical Society media briefing that included Jane and several of her colleagues. Like many of you, I was thrilled, and I knew I'd want to make her our guest on Planetary Radio. And here she is, direct from the United Kingdom.

Mat Kaplan: Jane Greaves, thank you so much for joining us on Planetary Radio and congratulations on this ... I was going to say earth-shaking, I'll call it world-shaking, maybe neighboring world-shaking, discovery, or at least the data that indicates such interesting things happening in the atmosphere of Venus. Welcome to our show.

Jane Greaves: Thank you very much, it's a great pleasure to be here.

Mat Kaplan: It is hard to believe it's only been a bit more than a month since this big announcement was made, and the publication of your findings in Nature Astronomy. Where were you and what did you do when you first saw data that indicated this find? This big dip that you saw in the data coming back from the James Clerk Maxwell Radio Telescope?

Jane Greaves: Well, let's see. We didn't really get the data live, because they have to be taken at the telescope, and that's all done remotely. And then the data was sent to us and I spent ages thinking there was nothing there. And then I was actually making a research visit to Cambridge University in England. That gave me some extra time to do projects that were a little bit on the back burner, however exciting. And there was one evening, I was just kind of pushing the data around, and then suddenly I realized they came together and showed us this absorption line. They showed us at this particular wavelength, the light of Venus, had dipped at this particular part of our spectrum, and that just blew me away. I'm like, "There really is phosphine doing this."

Mat Kaplan: There's no missing it. I mean, it really is a pretty impressive result when you look at that graph.

Jane Greaves: Yeah, the first one from the James Clerk Maxwell telescope, you could kind of attack it in various ways and go, "Maybe it's not quite as good as it looks." Then we got follow up data with the network of telescopes down in Chile, the Atacama Large Millimeter Array. We had the power of 45 telescopes working for us then, then I think after we processed that, that really jumped out and hit us in the eye.

Mat Kaplan: One of the things we're going to link to is that overlapping of this data from these two great telescopes. And it really is very, very impressive as so many people have commented. I have no right to be, but I'm always a little bit proud when I see wonderful data coming from ALMA, because I was there for the dedication of the telescopes, and was actually up there at the high site among the dishes for a few oxygen-starved minutes.

Jane Greaves: Oh, wow.

Mat Kaplan: So I'm always [inaudible 00:10:15].

Jane Greaves: I'm really jealous of you, I've actually never traveled there. I've worked with several ALMA datasets they've taken for us. But I would love to go, it's amazing, right?

Mat Kaplan: I highly recommend it. It's such an amazing place to be, even if you don't go up to where the dishes are. But bring your little can of oxygen if you go up.

Jane Greaves: I'm used to that from working in Hawaii, which is a bit lower, it's 14,000 feet, but you're certainly wondering where the oxygen went.

Mat Kaplan: Yes. So I've heard. And I haven't made it there, someday I'll get up to the top of that mountain.

Jane Greaves: Oh, you should go there. That's a very special place.

Mat Kaplan: I'm looking forward to it. Someday I definitely will. Were you looking for phosphine when you started pointing this great radio telescope in Hawaii at Venus? I mean, you did have it in mind, didn't you?

Jane Greaves: Yeah, the observation was designed to do that. So you don't get very much bandwidth with typical radio telescopes. You can't just look for all sorts of chemicals whose transitions would be at a whole bunch of different wavelengths. So we have to request this, and we had to say why we wanted to do phosphine, this pretty much not thought about molecule. So I proposed that very much as a search for a biosignature. And I kind of admitted this sounds a bit crazy, you know, Venus?

Jane Greaves: You have this call out for people anywhere around the world, who say they've got a project that could be done in less than eight hours, and the staff can basically do it for you and send you the results. I said, "Under this thing that you offer, can we have a go at this? Because it looks technically feasible regardless of what you think about the likelihood of finding a biosignature." And pretty much in my mind was like, "We're going to get a limit. We're going to not see it, but we'll be able to rule out a few hypothesis about the cloud decks. That's interesting enough." So they agreed and gave it a go.

Mat Kaplan: Tell us about this odd, simple, little molecule. I watched a video on the Royal Astronomical Society site, interview with you, in which you called it ammonia's evil cousin.

Jane Greaves: Yeah. So the chemical formula for phosphine is PH₃. So that's one phosphorus atom, and if you think of it as those ball and stick models you played with as a kid, or did in chemistry lab at school, you've got three hydrogen atoms sticking off that phosphorus atom. So ammonia is something we're much more familiar with, it's a nitrogen atom with three hydrogens sticking off it. So if you think of things that produce ammonia on Earth, that's kind of stinky and toxic. But phosphine, with the heavier phosphorus atom is actually much worse. We're really lucky that there isn't a lot of it in our environment, because it's very poisonous to larger creatures like us.

Mat Kaplan: And yeah, it seems on Earth, it's produced industrially, like so many other toxic things. But it's also a biomarker on our planet, and that is the suspicion, right? On Venus or at least the possibility that it is serving the same purpose there?

Jane Greaves: That's why we did it, because it's such a distinct biomarker as we could call it on the Earth. I wondered if it might also be true on Venus. So on both planets there isn't a lot of free hydrogen around, so something that's PH₃ you're not going to naturally get a lot of. So it's been found on Earth, like you say, in factories for various reasons. It's used in fumigation, but it's found naturally in places like swamps which are fairly oxygen-free environments as well as hydrogen free. But there are bacteria there that don't need oxygen, and they don't like oxygen even.

Jane Greaves: So they have a completely different lifestyle to things that we normally think of, like plants and animals. And they out phosphine gas, possibly as a waste product. They're just kind of shedding something that's part of the way they operate. So you can detect their presence by looking for this phosphorus-bearing gas. So we thought, "Well, if there's these some kind of very distant analogs to such organisms floating in the high clouds of Venus, they might also put out phosphine. So why not use a very small amount of telescope time to look for it?"

Mat Kaplan: How much phosphine has actually been detected in this work by your team?

Jane Greaves: Fair and very low quantities. The number of phosphine molecules is about 20 for every billion other molecules in the atmosphere. And that would mostly be carbon dioxide and a few other things. So it's a really small amount.

Mat Kaplan: I absolutely marvel at our ability now, from tens of millions kilometers away, to point instruments at the atmosphere of another world and detect something in such small amounts. I mean, does it also, even though you do it for a living, does it also amaze you?

Jane Greaves: It does amaze me, yeah. And just kind of the amounts of energy we're talking about. So radio waves carry energy around as any kind of light or waves does, but it's pretty small. Radio technology is just really sensitive, so we can pick up these tiny signals. So Venus is like a radio object, a radio planet if you like. It's kind of bright as these objects go, compared to, I don't know, distant black holes in the universe or something. A planet next door to us is kind of a radio bright object. Because of the very small amount of phosphine, it was just producing this tiny deck in the light. It's about 1/10,000th at this narrow range of wavelengths. So we were looking for a very small effect. So it does amaze me we were able to detect it, yes.

Mat Kaplan: From what we know of Venusian atmosphere, how stable or long-lived would phosphine be in this hellish environment? I mean, even at the altitudes where you think this exists, which we should also talk about, it's a pretty nasty place.

Jane Greaves: Yeah, so we think the molecules, whatever their sources, eventually drift upwards. That's a reasonably quick process. And once they get really high in the atmosphere, like maybe 80 kilometers, 50 miles or so, above the surface, then they're subject to sunlight really strongly, and that probably splits them apart and they don't exist any more. So at that height, they probably only last, oh maybe, 15 minutes or something.

Jane Greaves: So we're still looking in detail about how long they'd last at the altitudes, and kind of the middle and upper clouds where we're thinking they originate. So that might be a bit of a longer lifetime, but not so long that they could be there because of some very long past event, millions of years ago or something. That won't work, because they will be destroyed. So we do need a reasonably active source of the phosphine for it to be there for us to observe it.

Mat Kaplan: This makes me think of the search for sources of methane on Mars, and those findings which are inconsistent, but it seems pretty clear that it would have to be produced on an ongoing basis. Do you see that parallel as well?

Jane Greaves: Yeah, the methane on Mars is a fasinating problem. So as I understand that if there is a biological source, it's probably also some kind of simple bacteria, microorganism. Probably below the surface where it's safe from radiation which comes rather easily through Mars' thin atmosphere. So different amounts could be bubbling out according to what some subsurface colony is up to. And then that does make it really hard to reconcile. Because some of the measurements are like you see the planet at once, and some of them, if it's got a sniffer experiment on a rover you're seeing only a tiny part of the picture as you trundle across the soil. So that's a really complicated problem to analyze, although it is fasinating.

Jane Greaves: And the Venus one is complicated in a similar way, because the clouds, even if microorganisms have anything to do with it, they're probably not packed with a solid volume of microorganisms. There might be colonies shifting, and evolving, and blowing with the winds. So in detail, a picture that's going to be quite hard to understand.

Mat Kaplan: By the way, I actually prefer the pronunciation of methane that you folks in the UK use. I really should get into that habit.

Jane Greaves: I have enough trouble with aluminium, aluminum. I just want to make sure I'm being understandable.

Mat Kaplan: Yes, fortunately, we speak more or less the same language.

Mat Kaplan: That's Jane Greaves. She'll be back with more about the exciting discovery of phosphine and Venus in moments. This is Planetary Radio.

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Mat Kaplan: How are you able to get an idea, or did the team get an idea of where you are detecting this phosphine? Even if it's not being created at that altitude above Venus?

Jane Greaves: We do have a rough idea, because we know at the wavelength we were observing at, which is radio waves with a length of about one millimeter. We know they don't get out from lower in the atmosphere, the atmosphere itself is opaque. So we've got this kind of opaque layer at about 55 kilometers up from the surface, so that's, I guess, about 30 miles. So any molecules we see doing this absorption, they have to be above that.

Jane Greaves: So that gives us an idea of what the temperature, and pressure, and so on are like where the detectable phosphine molecules are. And that's interesting, because the temperature is up to maybe 20 or 30 centigrade, so 30 centigrade, so I think is about 85 Fahrenheit, that kind of is a nice day. The pressure is something like maybe up to half that of the surface of the earth, half a bar. So this seems reasonably nice conditions that wouldn't be too hostile to organisms. It's everything else there that's hostile. So the very high winds, and the high level of acid.

Mat Kaplan: I want to follow up on that. You talked about the anerobic life, life that exists without oxygen, the fact that oxygen is toxic to here on Earth, and maybe some of it emits phosphine as a waste gas. Has there been speculation about why living organisms on Venus would also be emitting phosphine? I mean, also possibly as waste, is there other speculation?

Jane Greaves: Yeah, this is all so new, and we are trying to be really careful in saying like, "We really have no direct evidence it's life. It's just a fasinating possibility." And, as I said, a super challenging place. It might turn out to be a place that is totally sterilized and the phosphine comes from something else. And then one of the surprises to me in this project is that we don't really understand phosphine production on Earth, and that may be because it's not been a super interesting thing to study. I mean, you can use it to trace that there are organisms, but the idea as to why they produce phosphine is still pretty unclear.

Jane Greaves: And it's not sure if some of that is also chemicals, there has been a suggestion that phosphides, compounds dissolved in water, that some part of the origin in the swamps, say, might not be biological. As far as the organisms, you can certainly culture them in the lab and measure the phosphine coming off. It's still not really clear, because you can't really ask a microbe what it's up to.

Jane Greaves: So it might be a waste product, there have been some ideas it's kind of useful for what I believe is called signaling between microbes. And I don't quite know how that works. Also to do with some processes like capture of metals, chemically it could be useful. Or even, because it's toxic to a lot of other stuff, maybe you can poison your next-door neighbors who are some different kind of bacterium. It's something I really hope somebody's is out there in a swamp, bravely figuring this out.

Mat Kaplan: Why, I was about to ask, have you heard from any astrobiologist colleagues who now are putting together expeditions out into swamp with the incentive provided by your findings?

Jane Greaves: We actually haven't yet, but possibly they're in the swamp not doing anything. And some of the places you do this work are quite remote, so some of the places where anerobic bacteria and phosphine have been measured are places like deserts in Namibia, a very different environment, but apparently a very productive one. I believe those experiments, those field trips, are really tough. They take a long time in the planning to get to these very unique environments, and, of course, at the moment with coronavirus, that's really not something people are going to be doing. It's just not a safe activity.

Mat Kaplan: No. We talk periodically on this show about extremophiles, and we have heard about living organisms that manage to live in these places on our own planet where no human would want to be caught for very long, including ones that are very acidic. But really nothing that compares to the Venusian atmosphere, I mean, I've seen some speculation about how would something living manage to stay alive where there is so much more acid than anything we found on Earth where anything is living? I mean, don't you have some of your colleagues on your team who are thinking about this?

Jane Greaves: Yeah, we have been thinking about this. We fully recognize this seem like crazy in some ways, because nothing on Earth has ever needed to adapt to this kind of environment change. So we don't know if it can be done at all. So there are organisms on Earth living in up to about 5% acid and that's incredible. That's really acidic. That's if you're thinking of pH that you did in your school lab, and the number goes down to like one or maybe zero for acid. The numbers beyond that actually have to be negative, if it's a lot of acid. So we don't know if something could evolve if the proportion of acid kept getting higher and higher and higher. And in the clouds of Venus, which we're trying to point out, you are talking about 90% acid.

Jane Greaves: So the reason the pH scale doesn't work is because it was designed for a bit of acid in a lot of water. Not a little bit of water in a lot of acid which is the situation in droplets that are supposed to exist in Venus' clouds. So maybe that's just crazy much corrosion, it's not possible. We're not sure about this, so one of my colleagues went and found some pure sulfuric acid and we did a laboratory experiment where he poured it on a cactus, a succulent plant. And actually it shed it, because the leaves have a very waxy coating, but after an hour it wasn't entirely as good as it was to start with. But this does give us some ideas that there are some coatings that are naturally acid resistant.

Jane Greaves: So I believe graphite is one, elemental sulfur would be another one, and sulfur's pretty common, very common in the clouds of Venus, so it's possible an organism could hide, make itself a little sort of shell of sulfur, but we have no analogous organism on Earth that would have to do that. And so we don't really know the answers to the questions like, "Well, then how would it get its nutrients inside if it's sealed itself in a shell? And how would it get its waste products, like maybe phosphine gas out?" So yeah, I would love to hear from more people who are like real biologists out some ideas on that.

Mat Kaplan: Well, I probably have listeners who are tired of hearing me say this, but it's a quote from that great scientist, Jeff Goldblum, in the movie Jurassic Park, "Life finds a way."

Jane Greaves: Yes. Well, that was a bit scary, because they mostly got eaten after the dinosaurs found a way, but-

Mat Kaplan: Right.

Jane Greaves: ... I mean, we can certainly do experiments to show that life doesn't always find a way. So there was an experiment to see if microbes could travel on space rocks, and they did that by taking an impact experiment that was going to land a kind of large probe-type thing on the surface of the Earth and see what happened. And as part of that experiment, they were allowed to put a coating of microbes on the outside. And life did not find a way, because the temperatures were so great, the surface was essentially either crushed or turned into a kind of melted glass. So even if it had survived a little bit deeper down, how were you going to get your way out through the glass? So they found nothing had survived. So we do want to caution, we're not saying just because life can find a way, it's going to find a way in 90% acid. Maybe it can, but that's still a very open-ended question.

Mat Kaplan: Yes. And one which I certainly hope a lot of people are investigating. You know, I heard several other researchers since this announcement was made who have made skeptical comments in one breath, immediately followed by their admiration for your team's work and the elimination of other possible sources, like lightning, volcanoes. My Planetary Society colleague, Casey Dreier, wrote a great piece along these lines for our website, but it does ... It is impressive to see the respect that your work has gotten even as other scientists have brought to it the very appropriate skepticism. I mean, is that how you feel?

Jane Greaves: Yeah, we put the paper out and as openly as possible, we said we really want other people to work on that from different angles. We really did mean everybody, so we attached the spectral data to the paper in a format that anyone who can work an Excel spreadsheet or a table at home can look at, just members of the public. And we asked the journal Nature Astronomy if they would make it completely free to access. You don't have to be a subscriber, and they immediately did that.

Jane Greaves: So we really do want people to work on this. And generally, yeah, people have been really positive, we've had a few ... So we have a new term, instead of mansplaining, we have this term, chemsplaining, of people writing in and say, "I saw a chemical reaction on Wikipedia which would clearly work." And then we're like, "We clearly explained why this wouldn't work. We literally write this down." So, you know. But mostly people are really reading what we wrote and thinking about it. It's been great. Had some fasinating suggestions.

Mat Kaplan: I suspect some of that chemsplaining was also mansplaining, but speaking of your team, if I counted right, there were 19 investigators listed at the top of that Nature Astronomy paper. Kudos from me as well, for making that free to the public, because it meant I could look it over as well. I was impressed by how many members of your team really provided important key contributions to these findings. It really seemed that lacking any of these major contributions might have kept this discovery from being so startling. I mean, they brought diverse skills, talent, and knowledge to this, didn't they?

Jane Greaves: Yes, that very much true. And it would have been very much lesser without that. I mean, I am an astrobiologist coming from an astronomy background, but it's the first time, I think, I've really worked so closely with people who are biochemists, for example, or lab spectroscopists. You know, vital parts of it depended on knowing it was definitely phosphine, not some other molecule, and looking at how many other sources we could rule out. The chemistry of volcanoes or something, I wouldn't have any idea where to start. And we had to explain each other's language a lot. I was like, "What does that word even mean?" Back and forth.

Jane Greaves: And I think that really helped, because you have to say, "All right, this is how I would explain it to my 12-year-old cousin or something," you're like, "Oh, now I understand what you mean." So yeah, that was really exciting and powerful, I think.

Mat Kaplan: One of your co-authors is astrophysicist Clara Sousa-Silva, I hope I have her named right-

Jane Greaves: Yeah.

Mat Kaplan: ... of MIT. Was it her work that helped lead you towards this discovery?

Jane Greaves: Yeah, she was really vital. So she does work on phosphine as a biosignature, and that was actually completely parallel. Because I was familiar with her work on it as a molecule, doing all the quantum physics calculations, but I never had the good luck to attend one of the talks where she talked about it as a biosignature which is her more recent work. In a way, that's good, because it shows two people can work on an idea independently, and I think that gives it some extra validity. So we used more the spectroscopy part of her work and she's an expert on all kinds of quantum transitions and all kinds of compounds. So that was vital in particular, that we were able to rule out sulfur dioxide as a contaminant at the spectral feature that we saw. That was really important there.

Mat Kaplan: It's a very impressive team. I've only mentioned one other person, Sara Seager, because she has been my guest several times and participated in that media briefing that you did. Another MIT person, and seems to have been another important contributor as well.

Jane Greaves: Yeah, very much, because she has this great bigger picture view of what we're doing with astrobiology, the search for life. So she brought so much to that, and particular, letting members of her team spend time on this project. So several MIT people were involved in bringing very different and very valuable skills. And you know, astrobiology tends to be funded by institutions and maybe charities interested in these big questions, but they're funding somebody with specific skills to work on a specific project. So it was great that we were just able to tap into some of that, essentially for free, because we needed some of these answers real quick. And people were able to go, "I have a model for that. Let me just run it over night, and I'll freely give you the answer." And we couldn't have done it without that.

Mat Kaplan: Science at its best.

Jane Greaves: Yeah. It totally was. It's been so exciting.

Mat Kaplan: If you don't mind this, I'm going to repeat a question that asked during that media briefing-

Jane Greaves: Mm-hmm (affirmative).

Mat Kaplan: ... more than a month ago. And that is what are you up to now? I mean, what's ahead? More telescope time? I mean, where is this going?

Jane Greaves: Yeah, certainly more telescope time and observatories around the world got really excited about this. The main issue really is coronavirus at the moment, because obviously, everybody's got to stay safe and telescopes are sometimes in quite remote places that you don't want to carload of people, or even people going on a plane to get to it, to take your new spectra. So that's in a little bit of a quiet and planning phase at the moment. But that kind of gives us time to dream, so we're doing some more on the chemistry.

Jane Greaves: Seeing if we've missed something, a whole load of actually useful suggestions that have come in, little things that we haven't quite included in the chemistry so far. So we're updating that work and dreaming a bit ahead to maybe sending a new space probe to Venus. Something that could maybe even survive for a while in the clouds and take modern measurements. It always astonishes me that the last descent probes that made it down and brought data back were the 1970s and 1980s. So nothing has actually been in the clouds, although there have been telescopes observing from in orbit, which have been very valuable, too. But getting something into the clouds, I think that's the dream for the next years, decade maybe.

Mat Kaplan: What would you think of a balloon mission as has been proposed for many, many years at Venus?

Jane Greaves: Yeah, I'm not really up on the technology of that and how you'd acid-proof your balloon, and so on, but something ... I've seen some of the beautiful illustrations of these ideas. Something that could drift in the clouds for weeks or months and do a really serious experimentation. That would be amazing. I mean, I think that is a longer scale project, because you're talking about launching a very complex thing that has to operate as an airborne instrument. That would be fantastic.

Mat Kaplan: As we speak, NASA is at least considering two missions to Venus, both of them orbiters. And there's been speculation that there might be time to adapt their instrumentation to do a better job or make them more capable of investigating this phosphine layer. I mean, would there be value in orbiters, if they did carry the right instruments?

Jane Greaves: Very much so, because a spectrometer floating above the planet can gather an awful lot more signal than we can from Earth, and so could get a very detailed picture. For example, where exactly the phosphine is on the planet, whether it changes with time, or that kind of thing, yeah.

Mat Kaplan: I'm going to switch gears here, as we near the end of our conversation. This was far from your first major discovery, I read about work you've done that ranges from moons to galaxies. It was only a couple years ago that you led work that points to tiny diamonds as being behind previously unexplained phenomena. I mean, what in the world, or what in the cosmos, was that about?

Jane Greaves: I'm very easily distracted is what that mostly shows. I was supposed to be working on planet formation, which is my main area. And we had broadband radio signals from these protoplanetary disks around young stars, and there was an odd feature in that that I couldn't explain. And eventually I made this connection to anomalous microwave emission that occurs in other environments and it's due to spinning nanoparticles. And then I found the circumstellor disk, protoplanetary disk, that I was looking at was one of very few astronomical sources that has nanodiamonds. So that was another kind of put the pieces together in a way that hasn't been done before. So that was also a really exciting project. I've got an undergraduate student doing a research project on that at the moment, so we can do more of these spinning diamonds.

Mat Kaplan: And we could go through, if we had time, more of your work. I mean, as someone who obviously very much enjoys doing science, has it been a nuisance dealing with the notoriety that has been gained by this latest discovery? These findings? I mean, you're constantly being bothered by people like me.

Jane Greaves: It's a pleasure being bothered by people like you. No, it's not been a nuisance. It's been overwhelming. It's kind of surreal, the BBC told us they would probably livestream our media briefing, and I was thinking, "Like you do for the White House?" I mean, I'm not used to this kind of thing. So in a way I had to pretend it wasn't happening and just go with the flow, but there have been so many moments of great messages from members of the public, and the excitement has really kept us going.

Mat Kaplan: Well, as I told you, all of us at the Planetary Society, and I suspect all of our members around the world, are absolutely thrilled by this work, and we congratulate you again. I got just one more question, it said in your bio at the Cardiff University site, "That you used textile art for exploring and engaging in astrophysics," that's a quote. I couldn't find any examples of your artwork.

Jane Greaves: Oh, no. I think they're on Twitter. Yeah, sometimes when I'm trying to picture something I love making it. I tend to do crochet which is very adaptable, so I have crochet asteroids, crochet protoplanetary disks. I did the moons of Jupiter for AstroFest, which is a public UK event. Yeah, more on Twitter, I should probably do this a bit more.

Mat Kaplan: I should connect you with a geologist friend of mine and former colleague, Emily Lakdawalla, who also turns her science into craft.

Jane Greaves: I've seen some of her beautiful work, yes.

Mat Kaplan: She will be delighted to hear you've said that. I will let her know. Thank you, Jane, this has been absolutely delightful. And, once again, congratulations to you and your entire team. I look forward, all of us look forward, to continued discovery and how do I want to say? Widening of this fasinating discovery in the clouds above Venus.

Jane Greaves: Thank you so much. It's been a pleasure to talk about it.

Mat Kaplan: Cardiff University professor and astrophysicist, Jane Greaves. She led and still leads the team that announced last month its discovery of phosphine gas in the atmosphere of Venus. Bruce will tell us where to find Venus in the night sky when we return and you might win a copy of Beyond Earth's Edge.

Mat Kaplan: It is time again for What's Up? on Planetary Radio. Bruce Betts is the chief scientist of the Planetary Society. He joins me as he does for every episode of this show. But this, this very segment, this edition of What's Up? is the very first official use of my new microphone. My new Electro-Voice RE20, I know you're impressed.

Bruce Betts: I am. And you just sound amazing, Mat. You've always sounded pretty terrible before, but apparently it's the microphone.

Mat Kaplan: It was, all along it was. I mean, this is the real me that people are finally getting to hear. So I hope they feel the same way you did. No, I'm just retiring a 20-year-old Rode NT1-A for you other microphone microphiles out there, is that what you would call it? Anyway, but I do like this new one and I hope everyone else will, too.

Mat Kaplan: Do you remember when you asked people a couple weeks ago to suggest callsigns that I would use as I climb into my F-22 and print it on the side of the plane?

Bruce Betts: Yeah, I kind of forgotten that, but I'm kind of excited now that you mention it.

Mat Kaplan: From Ian Jackson in Germany, he said, "Why, Ad Astra, of course." Cameron Landers in Texas, "Perhaps Mat's callsign could be Space Jockey, a Radiohead, or Airwave. That last one would also work pretty well for Mat's second career as an American Gladiator."

Bruce Betts: You didn't tell us about that.

Mat Kaplan: Got to bring in a little income on the side. Hans Christian Nielsen in Norway said, "The Astronaut." I wish. And then, Gene Lou up in Washington, he actually gave us a fairly long piece about pilot callsigns. I'm going to read this, "In regards to the additional query on your F-22 Raptor pilot callsign, most callsigns are derived from a play on the pilot's name, first, middle, last. Specific traits, exploits, feature, or skill. This can be complimentary, obscure, or insulting. And the more someone complains about it, the more it tends to be used." By the way, I should have mentioned, Gene works at an Air Force base.

Mat Kaplan: "We had a member who was given the name, Ralph. His name was Dave, but someone said he looked like a Ralph and it stuck. After a while no one actually ever called him by his first name, and new personnel really thought his name was Ralph. If you were talking to someone and said, 'I went downtown with Dave.' They'd say, 'Who?' And you'd have to say, 'Ralph.' And they'd go, 'Oh, okay.'" So the callsign that Gene thinks he could see as mine would be Freq, as in F-R-E-Q. Not bad, but guess what? He's got one for you, too.

Mat Kaplan: "Dr. Betts would be Factoid." Roger that, Factoid.

Bruce Betts: Roger that, Freq. Freq, break left.

Mat Kaplan: Thank you everybody, we've better move on. What's up?

Bruce Betts: Well, Freq, sorry, I've been trying that too much. So it is time for once in a blue moon. On Halloween, October 31st, the full moon will be a so-called blue moon, the most common definition of that being the second full moon in a month which doesn't occur very often, hence the term, once in a blue moon. Also on October 31st, Uranus is at opposition. So it is on the opposite side of the Earth from the sun, it's still really hard to see, but it means that it'll be rising around sunset in the east and setting around sunrise in the west. If you want to go after it, you're going to want a dark site, or some binoculars, or a telescope, and a finder chart that you can find online. It doesn't really change that much from one time of year to another, but technically it is the brightest point for time around of the Earth.

Bruce Betts: Yeah, Jupiter looking super bright over in the west, southwest, in the early evening with Saturn looking yellowish to its left. And Mars coming up around sunset, still looking super bright over in the east and then high up in the middle of the night. Venus still looking really bright in the pre-dawn. It's good planet time, and you can even notch Uranus on your F-22, Freq.

Mat Kaplan: Just a gorgeous crescent moon not far from Saturn and Jupiter last night. It was a really beautiful sky.

Bruce Betts: You're welcome. On to this week in space history. 2001, dun, dun, dun, dun, dun, Mars Odyssey went into Mars' orbit, amazingly 19 years ago. Still doing good stuff.

Mat Kaplan: I think Mars Odyssey threw something at the Mars Global Surveyor, because it wanted to stand alone in this longevity record.

Bruce Betts: Oh my gosh. Suspicion, scandal, a possible spacecraft murder plot? Wow.

Mat Kaplan: Battles in the sky above Mars, yes.

Bruce Betts: Onto random space fact. I was just thinking the other day, if you take the H from the end of the word Earth, and move it to the beginning, it spells heart.

Mat Kaplan: Aww, how sweet.

Bruce Betts: But I'm not sure that's a good enough random space fact, so I got another one relevant to today's show. Phosphine gas, you may have heard of it, possibly discovered in Venus' atmosphere, you did a show on that, right?

Mat Kaplan: Yeah, minutes ago.

Bruce Betts: Okay, well on Earth, I don't know if you discussed it on Earth, it's used in fumigation and sometimes to kill insects and rodents.

Mat Kaplan: It actually did come up, Jane mentioned that and various other uses. Nasty, nasty stuff which is a good reason, I guess, not to stick your head under the water in swamp.

Bruce Betts: Yeah, that's a good reason.

Mat Kaplan: One of many.

Bruce Betts: You don't need another. Well, I'm sorry I didn't know that, not having heard the interview yet. Glad I gave you that all important Earth, heart connection. Maybe it's two half-random space facts make a whole. On to a trivia contest. I had a whole trivia question for you. How many 25 meter antennas are at the Very Large Array in New Mexico? Kind of tricky, how'd we do, Mat?

Mat Kaplan: How about this with a reference to our poet laureate, but actually came from Allan Weinberg in New Jersey, it is one of the two answers I suspect you would accept or will accept. "27 is the number I found, if I am wrong, please expound, I am not trying to become the next poet laureate, I think you can tell by the rhyme ending this limerick." He added, "Thanks for the show, and I'm very happy to be an official member now." Welcome, Allan. Welcome to the Society, we're glad to have you.

Mat Kaplan: Then the other answer in this little ditty from Martin [Hojoski 00:46:40], "With one held in reserve, 28 dishes make that Jansky Array large, very movie stars for fulfilling Ellie Arroway's wishes, they catch star signals as they go around, merry." And I think it's a reference to the fact that they crawl around on tracks.

Bruce Betts: They do indeed, on railroad tracks. Technically, the answer is 28, although only being mostly familiar with the VLA you'd say 27, because that how many 25 meter dishes they've got out at any given time. But it turns out there's always one rotating into maintenance, so there's a 28th that is in the barn.

Mat Kaplan: Kirk [Sorb 00:47:19] in Colorado, he supplied 28 dishes, including a single spare. So I suspect he is our winner this time around. Congratulations, Kirk.

Bruce Betts: [crosstalk 00:47:31].

Mat Kaplan: Yeah, first time winner. He's going to get a Planetary Society Kick Asteroid rubber asteroid. By the way, he also suggest a callsign for me, you're going to love this, you ready?

Bruce Betts: Yes.

Mat Kaplan: MC Yammer.

Bruce Betts: MC Yammer. I like that very much.

Mat Kaplan: I actually do, too. I shouldn't, but I do. I think we are ready to move onto another contest.

Bruce Betts: Don't touch this dial.

Mat Kaplan: Freq.

Bruce Betts: This is Factoid, I got your new question for you. As of October 2020, so now, how many robotic, emphasis on the word robotic, space craft have returned samples to Earth from the Moon or beyond? Go to This, of course, relevant and you'll be talking soon to the head of the OSIRIS-REx mission about their sampling of asteroid Bennu.

Mat Kaplan: We sure will. Next week we'll be bringing Dante Lauretta back to the show. You have until the 28th, that would be Wednesday, October 28th, at 8:00AM Pacific Time. And someone is going to win the prize that I should have offered last week. We should have offered Beyond Earth's Edge: The Poetry of Spaceflight last week. So now we are, somebody's going to win a copy of this wonderful poetry collection. Brought together, edited by Julie Swarstad Johnson and Christopher Cokinos. My guest last week who joined me along with those nine readers of various poems from this terrific collection which is published by the University of Arizona Press. Get those entries in. Now's the time.

Mat Kaplan: And now's the time to say goodbye.

Bruce Betts: All right everybody, go out there, look up in the night sky, and think about MC Yammer wearing Hammer pants. Thank you, goodbye.

Mat Kaplan: Bolter, bolter, bolter, Factoid. Come around.

Bruce Betts: Punch out, punch out.

Mat Kaplan: That's my wingman, that's Bruce Betts, the chief scientist of the Planetary Society who joins us every week here for What's Up?

Mat Kaplan: Planetary Radio is produced the Planetary Society in Pasadena, California. That is made possible by its life loving members, you can live it up with them at Mark Hilverda is our associate producer, Josh Doyle composed our theme, which is arranged and performed by Peter Schlosser. Ad astra.