Planetary Radio • Mar 29, 2023

Volcanic Venus? New insights from vintage data

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Robbie Herrick

Research Professor at the Geophysical Institute, University of Alaska Fairbanks

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Scott Hensley

Senior Research Scientist at NASA Jet Propulsion Laboratory

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Bruce Betts

Chief Scientist / LightSail Program Manager for The Planetary Society

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Sarah Al-Ahmed

Planetary Radio Host and Producer for The Planetary Society

Is Venus hiding volcanic secrets beneath its shroud of clouds? Robbie Herrick and Scott Hensley, the minds behind a new paper on recent potential volcanic activity on Venus, join Planetary Radio to discuss their discovery and what it means for the future of Venusian exploration. Then we turn to the night sky with our resident stargazer, Bruce Betts, for What's Up and our space trivia contest.

Changing volcanic vent on Venus
Changing volcanic vent on Venus These two images from NASA’s Magellan spacecraft, captured eight months apart in 1991, show a volcanic vent on Venus that has changed size and shape. In the left image, captured in February, the vent has a surface area of 2.2 square kilometers (0.8 square miles). In the right image, captured in October, the vent has a surface area of 4.0 square kilometers (1.5 square miles).Image: Images from Herrick & Hensley (2023)
Maat Mons persective view
Maat Mons persective view This 3D view of Maat Mons, the tallest volcano on Venus, was created using data from NASA's Magellan spacecraft. The vertical scale in this perspective has been exaggerated 10 times. Maat Mons, appearing at the center, rises almost 5 kilometers (3 miles) above the surrounding terrain.Image: NASA/JPL

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Sarah Al-Ahmed: A volcanic discovery sheds light on the mysteries of Venus. This week on Planetary Radio. I'm Sarah Al-Ahmed of The Planetary Society with more of the human adventure across our solar system and beyond. Is Venus hiding volcanic secrets beneath its shroud of clouds? Robbie Herrick and Scott Hensley, the mines behind a new paper on recent potential volcanic activity on Venus join us to discuss their discovery. Then we turn to the night sky with our resident star gazer Bruce Betts as he brings us the latest celestial updates and test your space knowledge and our ever popular space trivia contest. We have some exciting news from the world of space exploration. A recent analysis of a small sample from asteroid Ryugu, which is brought back to earth by Japan's Hayabusa2 mission in 2020 has revealed the presence of uracil, one of the four essential building blocks of RNA. The sample also contains complex organic molecules that are crucial for life as we understand it. This new data puts us closer to understanding the potential role that asteroids may have played in the origins of life on our planet. We'll learn even more later this year with the return of NASA's OSIRIS-REx spacecraft, which is currently on route back to earth from another asteroid carrying even more samples. The JJames Webb Space Telescope has made a really cool observation while studying the atmosphere of an exoplanet located 40 light years away from earth. This intriguing planet known as VHS1256B orbits not one but two stars. It orbits about four times further out from its stars than Pluto orbits around our sun. JWST detected an array of molecules in this planet's atmosphere, including silicate dust grains, water, methane, carbon monoxide, and carbon dioxide. This discovery marks the largest number of molecules ever identified simultaneously on a planet outside of our solar system. It's an extraordinary achievement that really underscores the potential of JWST to revolutionize our understanding of distant worlds. A recent study has created a detailed map of the water distribution near the Lunar South Pole. Thanks to data from the now retired Stratospheric Observatory for Infrared Astronomy or SOFIA Mission. RIP, SOFIA. Researchers have discovered that most of the water around the Moon South Pole exists as ice hiding in the shadows of craters where temperatures are even colder than the average lows on the lunar night side. It's going to get really interesting when the next generation of upcoming lunar rovers begins exploring that region in earnest. If yours excited about humans returning to the moon as we are, you'll be thrilled to hear that the Artemis 2 rocket is making significant progress. Teams at NASA's Michoud Assembly Facility in New Orleans have successfully integrated the major structures of the space launch system rockets core stage for the upcoming Artemis 2 mission. Scheduled for November 2024, Artemis 2 will send four astronauts on a journey around the moon. This mission is a precursor to the next series of crude moon landings. I know I've said this before, but I'm so excited that humans are returning to the moon in my lifetime. You can learn more about these and other stories in the March 24th edition of our weekly newsletter, the down link. Read it or subscribe to have it sent to your inbox for free every Friday at We have a truly fascinating interview lined up for you as we explore the recent discovery of potential signs of active vulcanism on Venus. If confirmed, this finding supports long-held suspicions that the volcanic activity on our neighboring planet is still ongoing today. Venus is about 80% covered in volcanic rock and bears the scars of past eruptions, so it wouldn't be too surprising. The evidence stems from data collected by NASA's Magellan spacecraft, the last NASA mission to visit that world. It orbited Venus from 1990 to 1994. Two radar images captured in 1991, just eight months apart show a volcanic vent transforming from a circular depression into a larger kidney shape, a change that researchers interpret as a sign of active volcanism. Our guests this week, Doctors Robbie Herrick and Scott Hensley recently published these findings in the Journal of Science in a paper called, Surface Changes Observed on a Venusian Volcano during the Magellan Mission. They join us this week to delve into the implications of this finding as scientists continue to unravel the mystery of how Venus transformed from a potentially habitable world into the inhospitable hellscape we see today. Robbie Herrick is a research professor at the Geophysical Institute at the University of Alaska Fairbanks in, you guessed it, Fairbank's, Alaska, USA. With a keen focus on planetary science, Robbie has dedicated his career to studying the geological processes shaping various celestial bodies including the mysterious planet of Venus. Our other guest, Scott Hensley, is a senior research scientist at NASA's Jet Propulsion Laboratory in Pasadena, California. His impressive background and radar, remote sensing and a deep understanding of earth and planetary sciences made him an excellent collaborator on this paper. Both Robbie and Scott have been crucial to past and future missions of Venus, including NASA's Magellan spacecraft. Hi Robbie and Scott. Thanks for joining me on Planetary Radio.

Robbie Herrick: Thank you for having us.

Scott Hensley: Nice to be here.

Sarah Al-Ahmed: So you've just released a new paper that's about Surface Changes on Venus and it's gotten a lot of attention among the planetary science community. Even our guest last week, Lindy Elkins-Tanton, who is the PI for the Psyche mission, brought up this research because she was so excited about it. So what has your experience been like since this finding was released to the world?

Robbie Herrick: Sure. I thought it was a pretty important result and that it would get some press. I've kind of been overwhelmed with how widespread the coverage is and trying to soak in my 15 minutes of fave so to speak, and it's been pretty thrilling. I got to do interviews live on TV and radio around the world and I'm glad that there's renewing some excitement about Venus. Of course, there was a lot of excitement when these upcoming missions were selected a year or so ago as well.

Sarah Al-Ahmed: How about you, Scott? What's the last week been like?

Scott Hensley: It's been very nice to see all the interest in the result, first of all, and that's both from professional colleagues and from the general public alike. It's been really great to hear the excitement overall in the community. It's been really great for me as being a member of both the two of the upcoming Venus missions to see them being brought back to the forefront again and the excitement about people going back to Venus. It's been really great from on all fronts in terms of the interest in the result itself and in the broader implications for Venus Exploration.

Sarah Al-Ahmed: What got you both into Venusian exploration? Of all the planets in the solar system, why Venus?

Scott Hensley: Well, for me it was the first thing I worked on at the Jet Propulsion Laboratory. I was a mathematician by training in school. I didn't have the same pedigree that Robbie had and my first planetary mission at JPL was Magellan, and I've been a lifelong aficionado since that very first introduction to Venus. So I'm a radar scientist in terms of the things I've done mostly professionally and being able to apply radar to Venus. It's the ideal planet for radar exploration, so to speak, and I've been excited about it ever since.

Robbie Herrick: For me, I'd always had an interest in the space program till I was 10 years old. My father had worked for one of the contractors on the Apollo missions. An interest in the space program had always been part of family life. My degrees were in physics and geophysics in Texas. I was getting a master's degree at night and cold called a place. I later ended up working the Lunar and Planetary Institute, which is outside of Houston, and asked if somebody could give me a master's thesis topic that was in planetary science. So I started my career working with Pioneer Venus Gravity and topography data. From there I decided to get a PhD and I just happened to end up working for one of the co-investigators on the Magellan mission and that's how I became an expert in Venus Science. Now I can tell you all the reasons why Venus is way better than all the other bodies in the solar system except for ...

Sarah Al-Ahmed: Then I'm excited to hear it. A lot of these planets get a lot of love and there have been many missions to Venus, but yeah, if that planet is really tricky, it's hiding a lot of secrets and there's so much that we just do not know. Scott, we've observed volcanic structures on the surface of Venus in the past and it's pretty clear that the surface is relatively young and we've even seen some evidence from orbiters like Venus Express and Akatsuki that maybe there's some evidence in the atmosphere of current volcanic activity. But in the context of all of that, why is your discovery so exciting?

Scott Hensley: Well, as you said, there's been some evidence and indications that Venus is still active but they're indirect. So there are ones that depend upon chemical reactions in the atmosphere. Usually there are multiple pathways that similar chemical reactions can occur. One of them would indicate vulcanism, other pathways would indicate something else. There have been thermal anomalies on the surface again, but some of these things, how recent they were is not as clear as with our result. Our result is a visual indication of something of actually changing on the surface and we can actually say within an eighth month period exactly when it occurred 30 years ago. So it is really the smoking gun evidence of activity on the surface or the other ones were indications. This is not just an indication it is. There is activity on Venus right now.

Sarah Al-Ahmed: Which is so exciting. If that planet is currently volcanically active, that could have a huge bearing on how we feel about that planet and how it's changed over time. People have been really curious about Venus for ages, but it continues to make our life really hard as we try to research it. There's so many secrets we can't get to. Why is Venus such a challenging place to research and why is there so much disagreement and predictions on volcanic activity on this planet?

Robbie Herrick: It's particularly challenging to study from the surface simply because the temperature is, I think around 850 Fahrenheit, 450 C. The former Soviet Union landed a handful of landers which lasted a maximum of a couple of hours and even then is still quite difficult to do things. So what that has meant is that the science that has been able to be done from the surface is very limited because of your time limit. Not only is it an issue of the time on your surface, but the nature of the conditions are such that even if you can deal with keeping your instruments cool or functioning, there's also the issue of the power source and that if you're trying to do things right now, we don't have a setup where you could use solar power from the surface and there's a whole other set of issues trying to use something like nuclear power. So even if you can get things to survive, you're still going to end up battery limited on doing things on the surface. From orbit, synthetic aperture radar can see through the clouds without a problem. So that's a great tool. A whole bunch of other stuff has a lot of problems seeing through the atmosphere. If you look at Venus through a telescope, it looks like a fairly featureless yellow blob and if you fly right and put yourself right in orbit around it, it will still look like a featureless yellow blob and visible light. Then even in shorter wavelengths than radar where you can partially see through the clouds, that very dense atmosphere is refracting a lot of the light and dispersing it. So even though for instance, there's a window where you can see through the atmosphere in the infrared that's scattering of light by the dense atmosphere makes the resolution that you can get very low. You do have some options for say, floating around in the clouds at maybe 30 or 40 kilometers up, other than having sulfuric acid in the atmosphere, which is not too terribly difficult to deal with, but getting a balloon into the clouds is still a major challenge. So that makes the challenges pretty acute in terms of getting there. What Magellan revealed in very short terms is that Venus, and it should be this way, Venus, because it's roughly the same size as Earth, it has a similar amount of diversity in terms of the volcanic and tectonic structures that you see. So much more so than say Mars or the moon. So there are true mountain ranges on the surface of Venus. There's a huge variety of volcanic land forms, there's gigantic rift systems, plenty of evidence of things erupting and moving around on the surface, but we don't see things like the organized system of mid-ocean ridges that we have on earth. There might be a few things that look like arcs of subduction zones and we also don't see something like on earth where you can take high standing land forms and piece them back together like say, Africa and South America and get the feeling that you have clear evidence that things have moved hundreds or thousands of kilometers around. So Venus is very complicated tectonically and volcanically, but it doesn't seem to currently have plate tectonics. So what it has instead now and in the past there's been a wide variety of big picture scenarios that have been put forth to try and explain what we're seeing now. Some of those scenarios involve Venus be remarkably earth-like through most of its history and then changing dramatically to the point where there's some people that think Venus had plate tectonics and had a habitual atmosphere until the last billion years ago. But there's other ideas in terms of one of the issues is that all of the things we associate with plate tectonics are really about a planet that is hotter than outer space cooling off. So when you come up with these scenarios, there are flavors where Venus is comparably active to earth now and backwards in time, but it's just doing things differently. Then there's other ideas where to get similar overall levels of heat coming out on Venus, just like the earth, what you do is you dramatically fluctuate up and down the volcanic and tectonic activity so that right now, you end up with a Venus that is remarkably less active than earth, but you balance that by having it way more active at some time in the past and you cycle through that. To bring it back to this particular discovery, there was a lot of evidence that everybody agreed that future volcanic eruptions are going to occur on Venus and that Venus is volcanically active in some sense, but how often those eruptions take place could be on time scales of every few months, every few years or every 10,000 years. We didn't really, there were ideas that you could make any of those options fit with what we had before, but now of course there's what data settle one. So there's the possibility we might have found the only thing that's happened on Venus in the last million years and we just got lucky. But realistically, I think this brings Venus into a comparable level of volcanic activity to at least earth's big basaltic shield volcanoes like Iceland, Hawaii, the Canary Islands, that sort of thing.

Sarah Al-Ahmed: You pointed this out, but Venus might have changed dramatically over time. So Scott, why is it that understanding volcanism on Venus can tell us more about how the planet has changed over time? What makes us think that Vulcanism could have played a serious role in changing Venus from this potentially habitable world into this lead melting face melting hell scape it is now?

Scott Hensley: First of all, I mean all planets evolve over time and for a planet this size, we always expect volcanism to play a role of one form or another. It's the question of how it's structured. I think Robbie went into great length in terms of how volcanism may be structured as a function of time. Is it organized around play tectonics? Is it organized as intense periods of activity followed by very quiescent periods? It's the spatial and temporal organization of the volcanism that's really in question, not that volcanism would be involved at all. So what we've seen on the surface of Venus of course is that it is extremely volcanically active or has been in the past and influenced a lot of the evolution of the planet. The question is then which one of these theories that has been put forward really best represents how that evolution occurred and in what timeframe it did? Maybe I can give a little bit of background how people determine the ages of surface and when things occurred is crater counting, basically looking at the size and distribution of impact craters on the surface. Unfortunately for Venus we have what's called basically a uniform distribution. So unlike places on the moon or Mars, we can't tell relative ages of elements very well on the surface of Venus. So we don't have one of our great key indicators of time or how things evolved in time. So that's one of the things that a lot of these theories still open on the table. And one of the things we might hope with these newer missions with the better resolution and additional tools that they have been to the table that we might get some better idea on the relative chronology and that will maybe help us separate some of how Venus evolved over time. Questions answered.

Sarah Al-Ahmed: Don't you love that when something just throws you for a loop that tells us that there's some interesting physics going on there that could tell us a lot about planets in our solar system, but maybe even beyond exoplanets as well?

Scott Hensley: That's certainly the case and it's one of the things that excites the community is what are the broader implications. Laboratory we have in our solar system is Venus, the earth, Mars and the moon. So we definitely have to understand that first before we have a chance of really understanding the broader implication of what's happening with rocky body evolution around the galaxy.

Sarah Al-Ahmed: This research just goes to show that past spacecraft, like Magellan still have a lot to teach us about our solar system, but as you said, Robbie, trying to find a feature like this on Venus is looking for a needle in a haystack. So how did you go about narrowing down your search for features like this?

Robbie Herrick: To give you a little bit of background, Magellan passed over every place on the surface of Venus during its imaging portion of its mission three times. But while it was doing that, the spacecraft was degrading, so the area that it actually imaged the second time around, it got about 35% of the planet or so and then about 15% the third time around and each of those was done with ... It wasn't designed to look for changes, it was done with a different imaging geometry. What I did in the search was I had a list compiled from various sources of top 50 prospects for change during the Magellan mission. Just started going through there some in terms of looking for changes with time, some of that repeat imaging is a lot easier to work with than others. Sort of the old story about the guy searching for his keys under a street lamp because that's where the light was good. I started in this one area that wasn't in my top 50 prospects, but it was the one area on Venus where two images were taken, separated in time with the exact same viewing geometry. Then I moved on from there to the prospects that were in the easier to work with data where I actually found something was in this area called Atla Regio narrowed in on the place where there were the two of the large largest volcano on the planet in terms of height and size and the number one place where you would expect to find a change is where we found a change. But it wasn't the first place I looked because it was somewhere where the images were particularly challenging to work with in terms of looking for changes. So that's how things went overall. Any funded scientist, once I found something, I stopped and wrote the paper. So there's a lot of other areas that still could be looked at and maybe have something found.

Sarah Al-Ahmed: But you bring up a really interesting topic, which is that as Magellan was going around this planet, it's taking images, but the viewing angle is very different as it's going around, which complicates this process. Scott, you were instrumental in taking this data and then figuring out how to glean information about it based on its different angles. So can you tell us a little bit about that process and what you did to make this data make more sense?

Scott Hensley: Robbie sent me the imagery in an email and saying, "Look, Scott, I think I found change on the surface of Venus," and I was cautious about that because people had sent me things like this in the past and every single time I was able to prove that there was nothing that changed. It was really just an imaging geometry difference from the way the sensor collected the data. But when I looked at Robbie's stuff, I was cautiously optimistic right away that he really found something, but I really wanted to make sure that this couldn't be confused with just, we just looked at this from two different perspectives and it just looked like something changed and something really did not. So what I did is I used some knowledge about how radar really works and one of the images, we could get a pretty good idea of the shape that was on the surface and we know what Venus looked like generally, so we could figure out basically what the topographic profile looked like. With those two pieces of information and knowing which direction the radar was looking at, the data is possible to simulate what the images should look like. So what we were able to do then is we took the two different imaging geometries plus our assumed shape of the crater, and then we made simulated look images that we could then compare to the real images and we did lots of different variations of the crater shape until we found things that matched the data. There was another vent that was nearby that we didn't think did change at all, and we could match that up on both images very, very nicely, but there's nothing that we could do that would match up the images up the first time and the second time for the vent that changed. Its shape was different. It was no longer round, it was kidney shaped. The way the backscatter, how bright it looked inside the vent was totally different than the models, so nothing looked right. So that gave us a lot of confidence that indeed the vent had really changed and we really found or Robbie's keen eye had really detected something that had changed on the surface.

Sarah Al-Ahmed: There are many different processes that can change the surface of a planet, but why is it that this specifically suggests volcanic activity?

Robbie Herrick: Morphologically, it's clearly a vent, although neither Scott and I are, what I would say true volcanologist. I in particular don't spend an enormous amount of time scrambling around on volcanoes collecting samples and things like that. So this vent, it is on top of a volcanic construct. That itself is off to the north of the main very tip-top of Maat Mons, which is this massive volcano that is I think nine kilometers high and covers an area that's over a thousand kilometers across. So it's clearly a product of lava erupting from that location. In the first image it looks like the eruptions, it's seized, so you've got a circular feature with a raised rim and inside, it looks like there's steep walls and it's few hundred meters deep. So that looks like what you would typically see is an evacuated vent where the eruption ceased. The magma that's underneath is withdrawn. In the next image. To me, it looks very similar, typical basalt shield volcanoes where then you get a new influx of magma and in the place where you erupted before something happens, you subsume part of this vent structure and you end up with a lava lake. We're careful in the paper though to put some caveats on there because through modeling we can demonstrate that the second image is not the same thing as the first image is different and not just attributed to the viewing geometry. We do not, however, have enough information to definitively get the shape before and after, especially in a volumetric sense. So we can't rule out the possibility that this first vent underwent some really bizarre spontaneous collapse that resulted in the second image. But on earth we have zero examples of a multi kilometer change in a feature on top of a big volcano where there's a change, but no eruption takes place anywhere. I feel quite confident that there wasn't a volcanic eruption somewhere in terms of my bets, and Scott may have a different set of bets based on his experience, but in my bet there's a 99.9% chance that some volcanic eruption took place in that location, but the things downhill are new flows. I don't know, you can ask Scott what his bets are, but that's my set of betting on what we found.

Scott Hensley: I'm highly confident that there was probably some volcanic origin for the change on the vent or the Caldera. I'm less confident about the new flow. I lean more toward, it can very well just be a difference in the scattering geometry on that particular area. I can't rule it out one way or the other. That one is one I just didn't have a strong feeling for as Robbie did. But the vent itself that we're both pretty confident about that one, I think the new missions that we've been talking about will go a long way to helping us understand what's really happening on the vent itself and on that potential new flow.

Sarah Al-Ahmed: We'll be right back with the rest of my interview with Scott Hensley and Robbie Herrick after this short message.

Casey Dreier: Hi, it's Casey Dreier. I'm the Chief of Space Policy here at The Planetary Society, and I just want to take a moment to thank you for being part of the world's largest and most influential nonprofit space organization. Together, we are on a remarkable journey to make a better future for humankind through space science and exploration. Your support in the United States enables our team, my team, to work to make sure every US representative and senator in our Congress understands why space exploration is a critical part of US national policy. From workforce technology to science to even international relations. Each year, we urge Congress to maintain robust funding for NASA's ongoing missions guaranteeing that they stay on course and achieve their scientific goals. Now look, there are 81 new faces in Congress and several returning members that are joining space related committees for the first time, all of these could influence NASA's future endeavors and already they have begun to discuss next year's NASA budget. The time to act is right now. So in addition to writing Congress yourself what you can do if you live in the United States, there's something you can do to bolster our advocacy work and anyone can do this anywhere in the world and that's to make a donation. Thanks to the generosity of a fellow Planetary Society member, your gift today will be matched up to $75,000. This ensures our advocacy efforts will continue to thrive. Now, to make your contribution, you can visit On behalf of everyone at The Planetary Society, thank you for your support and helping us champion the future exploration of space.

Sarah Al-Ahmed: I'll put this question to you, Scott. There are a lot of missions going to Venus right now. We've got the Indian Space Research Organization, the European Space Agency, NASA, all of them sending basically a fleet to Venus. We even have private missions on the way to Venus right now. So this finding comes at a really opportune time. Would you have any advice for the people that are planning these missions, which includes you to take this information into account that might change the way that the design or plan these missions?

Scott Hensley: Well, we should be very careful. These missions going to Venus, some of them have some of the same instrumentation and some of them have very different instrumentation. So the ones that have a chance of seeing the surface have radars because of the thick cloud surface. There's four missions that I'm aware of that are thinking about having radars. There's the ISA mission, the NASA mission, the Indian mission, and the Chinese have also proposed a mission to go to Venus all with synthetic aperture radars. If you really want to look for change on the surface, the number one piece of advice that I have is you have to have similar geometry as you can between the different observations because that's what makes the job a lot easier. I'm want to emphasize how hard the job Robbie had to do was. Looking for changes in the data where it's coming from these different viewing geometries from opposite look directions. The way we did is something that only can be done by a human. We can't even train a computer algorithm to do this reliably. A lot of the image looks different. There were a lot of things that looked different in that image, but only the one thing really changed. So in order for this process to potentially be automated, and so we can really look at the whole surface of Venus, you really want to change the sensor viewing geometry so that it's consistently the same and then you have a chance to automate that process and look at wide areas of Venus and look for changes in a systematic way.

Sarah Al-Ahmed: We did share in the last show that the recent presidential budget request for NASA has had some impacts on the VERITAS mission, which is going to Venus and it's currently on an indefinite hold due to budget and workforce issues. So if this mission did get the fund to get needed, how would it help further our understanding of volcanism on Venus?

Scott Hensley: First of all, I've been working on the design of this mission for a decade, more than a decade, and so of course I'm disappointed that we're not flying to Venus on our original schedule, but we're still working with NASA to try to get the schedule to get an earliest possible launch as we can. We're scientists, I try to be truly optimistic about the chances of getting there and getting the data that we really need. Now, VERITAS is going to do something that is really desperately needed in terms of understanding of volcanism and a lot of other geophysical processes on the surface. That is it's going to make a high resolution topographic map of Venus. So right now, the topography, the resolution we have is about 20 kilometers, meaning we have an elevation measurement spaced every 20 kilometers on the surface compared to earth maps with topography where we have an elevation measurement, say every 10 or 20 meters on the surface. On VERITAS, we will make a map that has a resolution of 250 meters with really good height accuracy about five meters, and that's going to be a game changer for understanding the geophysical processes on the surface. That coupled with high resolution imagery of either 30 meters for globally or 15 meters for about 25% of the surface, those two things are dramatically going to change our understanding of a lot of processes on the surface and allow us to look for changes at a much smaller scale than we could with Magellan. You have to remember, a single pixel in the Magellan images is as big as a football field, so it's a pretty large area. So getting down to these smaller things will help us understand processes at all sorts of scales going on on the surface.

Robbie Herrick: With both the VERITAS and the EnVision missions. Any mission that flies a synthetic aperture radar in the future will have the ability to try and look backward from Magellan and see changes over at least a three decade, maybe four decade interval. But the limiting factor in terms terms of the scale of the changes is going to be the resolution and the Magellan data.

Scott Hensley: VERITAS is also planning to do something called repeat pass interferometry, which is a technique that's used on the earth all the time to map centimeter scale changes from volcanoes, earthquakes, and other geophysical processes on the surface, having this great observation that was made here, this gives us one target where we won't be able to do that for a very large fraction of the surface with the VERITAS mission, but we will having a target in mind where we can go and do this, it would really help us. If we can make an observation where there's these changes going on, it's like an x-ray, it's telling us what's going on beneath the surface. So it provides us an idea of what the Venus volcanic plumbing is really like. That's been my area of research for most of my career and I would be really excited to go back and get repeat past imagery over this particular vent to see if we could see something that's going on in terms of the volcanic plumbing on Venus.

Sarah Al-Ahmed: Honestly, planets like Mars get so much love. They have so many missions going there and I am so ready for the decade of Venus. There's so much that we don't understand and whether or not these timings all fall out just the way we want them to, just the fact that there's an renewed interest in this planet just really makes me happy and I can't wait to see what happens next. So what's coming next for your team? You hinted at the fact that you found your result and you immediately went to go publish that, but what's coming up next? Is there more research to be had on the subject for you guys?

Robbie Herrick: Both Scott and I are involved with both EnVision and VERITAS, and even with the delay at VERITAS, both of those missions are doing a lot of forward planning to get ready for eventual data collection. Right now, one of the things coming up for VERitas is to do airborne imaging of Venus analog areas on the earth to help us better interpret the structures that we will be seeing under the particular viewing geometry of VERITAS.

Scott Hensley: Yeah, so this is one of those experiments. Our first experiment's going to be done in Iceland starting this summer. This is one of the things where our international collaborations really pay off. The German Space Agency is operating this airborne radar that we plan to use and it actually has the two frequencies, the Magellan frequency and the VERITAS frequency basically that it can collect simultaneously. So this will allow us to collect data on Venus like targets with both of the wavelengths or the frequencies that the two radars operated at, and allow the scientists to build this understanding of what we would expect for certain types of structures with both the two radars that will enable us to better understand the data when we finally arrive at Venus, hopefully in the not too distant future.

Sarah Al-Ahmed: Does that mean you both have an upcoming trip to Iceland?

Scott Hensley: I think so. That's planned for the summer for me.

Robbie Herrick: I am not as central to this particular Iceland campaign as Scott is. So if they needed some extra warm bodies, I'll get to go to Iceland.

Sarah Al-Ahmed: Sounds like an excellent time. Well, it's going to be really exciting. There's a lot of things coming out about Venus and it's just going to get better. So if you ever come up with some really excellent new data on this, if you find some really cool new Caldera or vent out there, please let me know because I would love to share it with everyone.

Scott Hensley: We would be happy to do so, Sarah.

Sarah Al-Ahmed: Well, thank you both so much for joining me on the show and I think you've blown a lot of people's minds with this one. So we've all got a lot to look forward to in the future and thanks for joining me.

Robbie Herrick: Thanks for having us.

Sarah Al-Ahmed: Every so often, I like to pull up the only images ever captured from the surface of Venus, which are taken by Russia's Venera missions in the 1970s and eighties. I try to imagine what it must be like to be there in this moment. That cracked ground, the acidic yellow sky. Not to mention the catastrophic pressures and face melting temperatures. There's so much that we don't know about that place despite it being so close cosmically speaking. It's exciting to think about what we might discover in the next decades as more missions from around the world visit our planetary neighbor. As we mentioned in the interview, NASA's upcoming VERITAS mission to Venus is currently on hold and needs our advocacy. No matter where you live, you can help by sharing the #saveveritas on your social media channels. If you live in the United States, we've created an easy form that lets you contact your representatives in Congress to support the mission in just a couple of minutes. Visit and click on, "Save the VERITAS mission to Venus." With our powers combined, we can help save VERITAS. Now let's check in with Bruce Betts. The chief scientist of The Planetary Society for what's up. Sup, Bruce?

Bruce Betts: Yes, that is the name of the segment, Sarah, although you seem to have conflated the words together. What's up?

Sarah Al-Ahmed: Sup? I stand by it. But I had all these grand plans to actually escape my gamer den after recovering from COVID. Go outside, take a look-up at Venus, maybe think about volcanoes or something, and then just torrential rain. So I've not been able to go outside and see the beautiful sky in quite a while, but if I do go out this week, hopefully it won't rain as hard.

Bruce Betts: There are probably people who can see the sky. For those people, Venus, easiest thing you can see over there in the West. Super bright looking, fun looking, fabulous. If you look up high, you can see Mars and Mars and Orion and Taurus, Rigel Star, Aldebaran, they've been hanging out for a few months together. Yeah, they're done. They're growing apart over the next few weeks.

Sarah Al-Ahmed: They're growing apart.

Bruce Betts: As a result, Mars is dimming. No, it's related, but that's not actually like ... Mars is getting farther away from the earth. So I've been saying it's been dimming, but it really will dim significantly. Right now, Aldebaran is brighter. This is for those who want to play with Rigel Stars in the sky and their brightness. Aldebaran has been the dimmer one, but now it's a little bit brighter. Mars will keep fading as it runs away. Don't worry everyone, it'll be back every 26 months clock worth whether we want it to or not. All right, I'm pretty done. Pretty done, people. Saturn, go out there, check it out in the [inaudible 00:42:09] East. Back to those constellations, we're we're going to have Orion and the gang running away pretty soon, so check them out. Getting lower in the sky, moving towards the west as the weeks go on.

Sarah Al-Ahmed: Yeah, it's that moment when winter up here in the north ends spring rolls on in and Orion just runs away.

Bruce Betts: If we move on to this weekend space history, it was 1974 that Mariner 10 did its first flyby Mercury giving us our first spacecraft view of Mercury, and it would do a couple more flybys and we'd image more than 50%, then wait till 2008 for messenger to capture the rest of it. Turns out, it's gray and covered in craters. Shall I move on?

Sarah Al-Ahmed: Let's do the thing.

Bruce Betts: Random space food.

Sarah Al-Ahmed: Did you catch? We did that chainsaw thing on you last week. That was super fun.

Bruce Betts: That was new. That was exciting.

Sarah Al-Ahmed: I know.

Bruce Betts: This one needs something. It was ... I don't know what it was, but maybe it's because I'm going into what's kind of not a normal random space fact. But then I thought about it and it's a fact and it happened in space and it is quite random. I just thought it was a neat story, which is from an article that astronaut Tom Jones wrote, interviewing Bob Stewart, the astronaut Bob Stewart, who is the second astronaut fly untethered in space. So you have the iconic Bruce McCandless picture floating over the earth in the man maneuvering unit, and we'll get back to that. Dun dun dah. But Bob Stewart then did the second flight. He thought, what would it be like to be the only person in the universe? So he turned himself to where he couldn't see the earth, the moon or the sun, only the blackness of space. I only lasted 15 seconds and I thought, "Well, let's just turn around and make sure everything's still there."

Sarah Al-Ahmed: That sounds horrifying. As much as I want to go to space like floating, untethered in space, staring into the darkness, the vast expanse. That's horrifying.

Bruce Betts: You conjured quite a vision. So I thought I would share, but now we will move on to the trivia contest. I asked you name all the countries whose national flag as some representation of the Southern Cross Asterism that is part of the Crux constellation. How'd we do with this one?

Sarah Al-Ahmed: Oh, the beautiful Southern Cross. Yeah, we got a lot of answers from all over the world on this one. The dice have spoken and Allison Benfield from Charleston, South Carolina, USA is our winner. The answer is Australia, New Zealand, Papua New Guinea, Samoa, and Brazil. So no surprise there. Countries that can actually see the Southern Cross.

Bruce Betts: Oh, oh, I get it now.

Sarah Al-Ahmed: Yeah. But I loved, actually this made me really happy because every so often people say in the comments like, "I've never won. I wish I could win this contest." Well, Allison wrote in and said, I have terrible luck when it comes to winning this contest and perhaps the odds will be in her favor this time. So I would like to tell you, Allison, the odds are ever in your favor and you got it this time.

Bruce Betts: The dice have spoken.

Sarah Al-Ahmed: Yeah.

Bruce Betts: Oh, that's cool. Congratulations.

Sarah Al-Ahmed: We got a lot of wonderful comments on this one. I loved this comment from Joel Caliputre from North Middleton, New Jersey, USA, who said, "I wonder if Penguins in Antarctica would choose to put this Asterism on their flag if they created a country. I don't know what penguin eyes are like or if they even look up at the stars or can."

Bruce Betts: I'm stuck on forming a penguin country. Any who.

Sarah Al-Ahmed: Also got this really cool like trivia fact. Norman Kasun a regular listener, wrote in and said, "The Southern Cross has been part of Australia's first nations' cosmology for millennia. When European Voyager got there in the late 15 hundreds, they took it as a sign of their divine blessing for conquest. But then even after that, it was a symbol of rebellion for the Eureka stockade, which was part of the Eureka Rebellion. That was a series of events involving gold miners that revolted against the British administration in Victoria, Australia. So this Asterism apparently has a long history in Australia of having all kinds of meaning to different movements there. It's fascinating." Strangely too, Victoria is where I saw both penguins for the first time and the Southern Cross.

Bruce Betts: Whoa, going back to flying around tether list and space, who took the iconic picture of Bruce McCandless floating untethered over the earth during the first flight of the man maneuvering unit? Who was the photographer? Go to

Sarah Al-Ahmed: I imagine it was someone having a deep existential crisis because that image terrifies and amazes me. Everybody out there, you have until April 5th at 8:00 AM Pacific Time to get us your answer and whoever wins this will be the lucky winner of another Goodnight Oppy thermal mug. We keep getting people who want another chance to win that. So we'll be giving out another Goodnight Oppy thermal mug. Of course, Goodnight Oppy is a lovely documentary about the Opportunity Rover on Mars. So here's your chance fam. We got you.

Bruce Betts: Cool. All right, everybody go out there and look up for the night sky and think about looking out into the night sky and try not to have an existential crisis. Thank you and goodnight.

Sarah Al-Ahmed: We've reached the end of this week's episode of Planetary Radio, but we'll be back next week to celebrate two years of the Emirate's Hope mission to Mars with Mohsen Al Awadhi Director of the Space Missions Department of the UAE Space Agency. Planetary Radio is produced by The Planetary Society in Pasadena, California and is made possible by our Venusian Volcano loving members. You can join us as we continue to puzzle over Venus' strange history at Mark Hilverda and Rae Paoletta are our associate producers. Andrew Lucas is our audio editor. Josh Doyle composed our theme, which was arranged and performed by Pieter Schlosser. Until next week, ad astra.