10-Extinctions: Showdown of the giant space rocks

Dani DellaGiustina is one of the youngest leaders of a NASA mission, and she was in charge of image processing for OSIRIS-REx before she even got her PhD. OSIRIS-REx is a spacecraft sent to study asteroid Bennu and scheduled to return a sample to Earth in 2023. Dani walks us through the difference between asteroids and comets—it turns out there’s some overlap! There’s even a thing called “extinct comets,” and some think Bennu might be one, but Dani isn’t so sure. Along the way, Dani tells us about her non-traditional career path and attempts to avoid polar bears in Greenland.

This episode was produced by Katrina Jackson and mixed by Collin Warren. Cover art, editing, and production assistance by Jace Steiner.


Shane Hanlon:              00:00                Hi Vicky.

Vicky Thompson:           00:00                Hi Shane.

Shane Hanlon:              00:02                So I wanted to ask you, have you ever seen a shooting star, or even got the opportunity to gaze up at a very dark and star filled night sky, and asking you this as folks, we both live in cities ish now and have a lot of light pollution.

Vicky Thompson:           00:19                Yeah. Yeah. So I’m sure I saw stars before this. I grew up in Northern New Jersey, which I’m sure I’ve mentioned, I mention it a lot, but so lots of light pollution. And I camped and everything when I was a kid, so I know I saw stars. But the first time it really, really clicked, I went to a science summer camp when I was in high school in the Adirondacks. Shout out to ESSYI, but we went camping for a few days in the Adirondacks to do some like sampling of water and things like that, and it was just so dark, and the stars were so bright. I feel like that’s my first real whoa moment.

Shane Hanlon:              01:04                Yeah. I grew up in very rural Pennsylvania, so I actually got to see a decent amount of night sky. But recently, and you and I will catch up on this, but my partner and I went to the Galapagos, and we were on a boat for like a week and a half and it was amazing. But one thing I was really looking forward to is just how dark it is there. I mean, the night sky is amazing.

Shane Hanlon:              01:26                It was cloudy the first or second night, I’d go up and just this beautiful, beautiful sky, and more stars than I’ve ever seen my entire life. While the boat was going through very choppy seas, and let’s just say that I enjoyed the night sky, but being on deck was more of a necessity than anything because the moment we’d get down in our cabin…. It took me a while to adjust to being on a boat. We won’t get into more than that, but the sky, absolutely lovely.

Vicky Thompson:           02:08                You just wrote a really good Yelp preview. Yeah.

Shane Hanlon:              02:11                I’ll make sure I include it.

Vicky Thompson:           02:13                Yeah.

Shane Hanlon:              02:19                Science is fascinating, but don’t just take my word for it. Join us as we hear stories from scientists, for everyone. I’m Shane Hanlon.

Vicky Thompson:           02:28                And I’m Vicky Thompson.

Shane Hanlon:              02:30                And this is Third Pod From the Sun.

Shane Hanlon:              02:34                So we got a little off topic in our introduction, as we do. But to bring us back on course, little bit of reeling us in, I’m going to bring in producer Katrina Jackson. Hi, Katrina.

Katrina Jackson:            02:48                Hi Shane.

Shane Hanlon:              02:49                Okay. What are we doing? What do you got for us?

Katrina Jackson:            02:51                Yeah. So I thought we’d start off with just a short pop quiz, if that’s okay.

Shane Hanlon:              02:55                Ooh. It’s not often that I get quizzed. I’m always asking Vicky questions.

Katrina Jackson:            03:01                Yeah.

Vicky Thompson:           03:02                I’m glad to have you on the carpet.

Shane Hanlon:              03:04                All right. Go for it.

Katrina Jackson:            03:06                Great. So can either of you tell me what is an asteroid?

Vicky Thompson:           03:10                It’s a rock.

Shane Hanlon:              03:13                Yeah, it’s a rock that is usually a world ending event.

Vicky Thompson:           03:19                That’s rock moving through space. Rock. Yeah.

Shane Hanlon:              03:23                Big rock.

Katrina Jackson:            03:24                Big rock. Okay. And, and what is a comet?

Shane Hanlon:              03:27                Big icy rock.

Vicky Thompson:           03:29                Oh yeah. I’m with Shane on that.

Katrina Jackson:            03:32                Okay. Yeah. Big rock, big icy rock. That’s pretty much about right.

Shane Hanlon:              03:38                I love being right. It brings me joy.

Katrina Jackson:            03:42                Right. So, and with a lot of things in nature, sometimes it’s a little hard to tell the difference, and it turns out there’s probably some degree of overlap between asteroids and comets. And there’s even a thing called extinct comets, where after a comet spends a lot of time near the sun and it loses some of that ice, it might look more like an asteroid. And so to help explain all of this, I talked with an expert on small solar system bodies from the OSIRIS-Rex mission.

Vicky Thompson:           04:10                OSIRIS-REx, is that an acronym?

Katrina Jackson:            04:12                It is. Yeah. So it’s a long acronym. I’ll see if I can remember it. So OSIRIS-REx is origin, spectral interpretation, resource identification, security, regulate, explore.

Shane Hanlon:              04:26                Yeah. We’ll clap for that. Very good. Very good.

Katrina Jackson:            04:31                I’m always a little proud when I can remember that whole thing. So OSIRIS-REx is a NASA mission that recently went to capture a sample from an asteroid named Bennu, and it’s currently on its way back to earth to return that sample. And so for this episode, I got to chat with the deputy principal investigator of that mission.

Dani DellaGuist…:         04:47                My name is Dani DellaGuistina, and I am the deputy principal investigator of NASA’s OSIRIS-REx mission. I’m also an assistant professor of planetary science at the University of Arizona.

Katrina Jackson:            05:11                What I’m hoping to learn about today is all about asteroids and comets. Can you explain what exactly is the difference between asteroids and comets?

Dani DellaGuist…:         05:22                Yeah, that is a really good question. So the difference between asteroids and comets in general is that asteroids tend to be small bodies, debris, in the solar system left over from the formation of the planets that is composed primarily of rock. And comets are pretty similar. They’re also debris leftover from the formation of the solar system, but they tend to be more icy. So they might have dust and rocks in them too, but predominantly they’re composed of ices and other volatiles. And when I say the word volatiles, I just mean a material that heats up and vaporizes really quickly compared to rocks, for example.

Katrina Jackson:            06:11                Is it easy to identify what is an asteroid and what is a comet, or is there a bit of overlap?

Dani DellaGuist…:         06:16                Yeah, so that is a really good question. There are things that we think of as being a little like asteroids and a little like comets at the same time. These are called transitionary objects. So they have characteristics of each. And when we think about the types of small bodies that exist in the solar system may probably exist more on a continuum between these two different classifications than in distinct boxes. So in some cases, it’s easy to tell the difference, but there’s some objects that leave a little bit of ambiguity.

Katrina Jackson:            06:51                Can a comet become an asteroid? I’m hearing about, quote, extinct comets, what is that?

Dani DellaGuist…:         07:00                That’s a really good question. So you could think of some extinct comets as comets that became asteroids, but what an extinct comet really is, is it’s a comet that’s expelled most of its icy material, those volatiles that I mentioned earlier. And that’s because comets that make their way into the inner solar system, every time they get close to the sun, that material will vaporize away.

Dani DellaGuist…:         07:28                So there are some objects that are, like I mentioned, transitionary, in the middle. But there are some differences as well. So we know that comets and asteroids formed in different parts of the solar system really early in its history, and that it makes sense because comets had to have formed far enough away from the sun that they could preserve those ices and volatiles. And they typically will have more, what we would say, eccentric orbits than most asteroids.

Dani DellaGuist…:         08:00                So their orbits have a slightly different shape versus asteroids. But there are some extinct comets that are out there, or some objects that we thought were asteroids, and then later after observing them further, we saw that they have some cometary-like activity, which just means that they might show a tale or a coma from time to time.

Shane Hanlon:              08:24                Okay. So it sounds like we were kind of right. So asteroids and comets, both small rocky bodies that formed in our early solar system. But in general, asteroids formed in the inner part closer to the sun, and don’t necessarily have much ice in them, whatever that ice might be made up of. And comets are from the outer solar system, so they may have ice. I get that that’s very simplistic, but I think that’s right. Right?

Vicky Thompson:           09:08                That sounds right, but there’s still some overlap. So there could be some that are in between an asteroid and a comet?.

Katrina Jackson:            09:16                Yeah. Yeah. So there’s some overlap. There might be some asteroids that have some more comet-like traits, or comets that have some more asteroid-like traits. And as we were discussing, there are extinct comets where the ices and volatiles in the comet have vaporized away.

Vicky Thompson:           09:32                Okay. So how does this tie into the OSIRIS-REx mission?

Katrina Jackson:            09:36                Yeah, so I didn’t realize that OSIRIS-REx had any direct connection to extinct comets until recently, but conveniently enough, as I was researching this story before the interview, I saw a paper from earlier this year that was proposing that maybe the asteroid OSIRIS-REx visited is actually an extinct comet. The paper was actually talking about different asteroid called Ryugu, which is the asteroid that Japan visited with their Hayabusa2 mission around the same time that NASA was visiting asteroid Bennu. But the asteroids Ryugu and Bennu are really similar, both in appearance and composition, so the paper was suggesting that they might have formed in the same way.

Shane Hanlon:              10:21                Does that mean that Bennu might have actually been an extinct comet?

Katrina Jackson:            10:26                Maybe. So I did ask Dani about this hypothesis, and she seemed skeptical.

Dani DellaGuist…:         10:37                I have seen that paper and I have some thoughts about it. So the idea, at least the idea that was proposed as part of Ryugu paper. So Ryugu is the dark top- shaped asteroid that looks a lot like Bennu that was visited by the Hayabusa2 mission. And this recent paper that came out suggesting that Ryugu is an extinct comet hypothesizes that the parent body of Ryugu was a comet, and over time as it made close excursions with the sun or migrated a little closer towards the sun, it’s icy and volatile material eventually evaporated. And what is left is the interstitial, or the in between, rocks and dust, and it’s almost like a lag. You can think of that as modern day Ryugu.

Dani DellaGuist…:         11:44                So as part of that paper they did draw the comparison, just like you did, Katrina, that Bennu and Ryugu are really similar and maybe could be a possible theory for Bennu’s formation. But the one thing that I noticed that paper did not account for is the fact that we have seen on Ryugu’s surface what we call exogenic material. And so that’s just material that originated from a different asteroid on its surface. And on Bennu, we saw really clear evidence of this as well. We actually saw material from asteroid Vesta on asteroid Bennu, which is wild. And, at least in Bennu’s case, the most probable way that that could have happened is on Bennu’s parent body. So Bennu is a rubble pile asteroid, we expected that it had a parent body, a bigger asteroid that was catastrophically disrupted and scrambled up by a big impact, and then Bennu formed from the fragments of that giant impact.

Dani DellaGuist…:         12:52                And on Bennu, we see, like I said, this exogenic material. So this material that came from a different asteroid, and we also see other signatures of impacts on it, like these things called retches. Which are when you have one type of rock mashed up with another type of rock. We see this with Bennu and that Vesta-like material.

Dani DellaGuist…:         13:14                And all of this points to collisions between rocky bodies closely after either before or during the formation of Bennu, and maybe during the formation of Ryugu, based on what they’ve seen, based on the Hayabusa2 data. So I think from that perspective, it makes the hypothesis that these bodies originated from comets that vaporized away and left over little debris piles a bit more challenging. And I would’ve liked to have seen some accounting of that evidence in this most recent paper on Ryugu.

Katrina Jackson:            13:52                Okay. So sounds like you’re leaning more towards thinking that Bennu is an asteroid and not an extinct comet?

Dani DellaGuist…:         13:59                Yeah. I think that Bennu and its parent body, there is a lot of evidence that there was water on Bennu’s parent asteroid. We see a lot of hydrated minerals on Bennu, and this isn’t free flowing water, but it’s water that’s bound up within clay-like minerals. And so I think these objects are probably somewhere in between the asteroid and comet ends of this spectrum of different objects, but I think I’m coming down pretty firmly on the side of asteroid.

Shane Hanlon:              14:34                So maybe Bennu might be more of just a soggy asteroid versus a comet.

Katrina Jackson:            14:49                Yeah. That’s what Dani tells me. And, full disclosure, I had actually met Danny way back in 2008. My research advisor while I was in undergrad at the University of Arizona was Dante Loretta, and he’s now the principal investigator for OSIRIS-REx mission. And Dani was in that same research group, we overlapped by a semester or two. Then eventually I went on to do science media, working with NASA as a freelancer, and Dani continued in research. But she didn’t really take the traditional academic path.

Dani DellaGuist…:         15:24                Yeah. So I’ve had a non-traditional career path in some ways, but in other ways, I’ve also been doing this for a really long time. So I got involved in the OSIRIS-REx mission before it was OSIRIS-Rex, when it was just called OSIRIS, and it was proposed as part of NASA’s discovery program.

Dani DellaGuist…:         15:44                I was involved as a student. I was the undergraduate principal investigator for a student collaboration experiment that was intending to measure the cosmic radiation flux around an asteroid and how it might decrease in the shadow of that asteroid. Even though that instrument never came to be, I got a lot of really good experience just working on a big NASA mission proposal, understanding what is required to build a space flight instrument, and learning the ropes of that whole process. Couple of years later when OSIRIS-REx was funded and being built for its journey to Bennu, I got involved on the image processing team.

Dani DellaGuist…:         16:31                I was eventually promoted to the lead image processing scientist, and then became the deputy principal investigator after our former deputy PI retired last year. So, in some ways, I’ve been working on this program for a long time. But in other ways, I went to grad school and I got a master’s degree shortly after my undergrad, but then I just worked for a number of years on this mission and developing other space flight programs.

Dani DellaGuist…:         17:02                And it wasn’t until just a few years ago that I went back and did a PhD and started entering a more traditional career stream in academia. But it’s all been driven by a really strong interest in our solar system, and how it formed, and what are the clues that we can gain by studying small bodies about that process of solar system formation.

Katrina Jackson:            17:30                So how much more responsibility is the deputy PI role than what you were doing previously?

Dani DellaGuist…:         17:38                I would say that the deputy principal investigator role, at this point in time, it doesn’t add more responsibilities necessarily, but they are different responsibilities.

Katrina Jackson:            17:51                I assume you probably at least have a bigger office now than you did in undergrad. I don’t know if you remember, but I actually took your old office in undergrad.

Dani DellaGuist…:         18:01                Oh, did you? That little closet. Yeah, I actually, our team just moved from the Drake Building, which is where we did all of the mission operations for OSIRIS-Rex, or science operations OSIRIS-REx back over to campus. So I’m in the Kiper building again, I do have a window this time.

Dani DellaGuist…:         18:35                So a couple of challenges that I’ve had, would say that I was operating at a research scientist, I was working as a research scientist, before I had a PhD. And while the vast majority of people were always fine with that fact, I would say that there was a small minority of people that I did think there was a bit of a bias because I didn’t have a PhD. Even though I’m operating grants and working in a research scientist capacity on a NASA mission.

Dani DellaGuist…:         19:13                And then when I was getting my PhD while working full time was extraordinarily challenging, and I’m not always sure if that was the best route to go. I can’t recommend it, but it’s the route I took and it worked out for me. So I think that those have been, taking this non-traditional path, not going right from my master’s into a PhD, and deciding to work and gain some experience beforehand, it’s definitely made things nonlinear for me, and there’s just been some challenges associated with that.

Dani DellaGuist…:         19:46                And then I became a co-investigator on an NASA mission when I was relatively young, as far as these things go. So it was my late twenties. And again, I think there’s just some biases that crop up when you’re a very junior person on the team, but you’re in a leadership and management role. That can cause some friction sometimes. But I think in the end, everything worked out. So I think if you know what you love to do, and you’re happy to get up every day and do it, that certainly can create a buffer against challenges.

Vicky Thompson:           20:36                All right. So that does sound pretty challenging, being a young person in a leadership position on a NASA team and not having your PhD yet.

Katrina Jackson:            20:44                It does, yeah. And that’s not the only challenge Dani talked to me about. She also told me about trying to avoid polar bears.

Shane Hanlon:              20:55                Wait, what? Polar bears, what are we talking about? This just took a turn.

Vicky Thompson:           20:59                Yeah. She works in Arizona, doesn’t she?

Katrina Jackson:            21:01                Yeah, she does. Yep. So Dani, while she was working with OSIRIS-REx, she was also, for the past few years, working on her PhD, and her PhD work was on a different topic altogether. She was helping develop seismometers for spacecraft missions to icy worlds like Europa, which is a moon of Jupiter. And shortly before the first images of asteroid Bennu came back from OSIRIS-REx, Dani was out doing field work in Greenland.

Dani DellaGuist…:         21:32                Right before the spacecraft got to Bennu and we could see it as a little world, not just a dot of light, I was doing a pretty extensive field campaign in Greenland. And there is a fairly substantial polar bear risk when you’re doing field work in Greenland. We have to sleep with trip wire around our tents and an electric fence around that. We all have to be trained to shoot a shotgun.

Dani DellaGuist…:         22:03                So I remember just being so concerned that something was going to happen in the field and I wasn’t going to see Bennu, and I had been waiting for so many years for this moment when our cameras were going to resolve the asteroid, and I was going to be able to see it as a world and not just a point source of light. And when you’re in the field, you’re doing a lot of pretty manually intensive work. We’re riding in helicopters on a regular basis. So there’s a fair amount of occupational hazards. And I just remember being so like, “I have to just get through this field season intact so I can get back home. I know those images are going to be coming down in two months and I need to see Bennu before I die.”

Katrina Jackson:            22:50                Oh no. Did you ever see a polar bear while you were there?

Dani DellaGuist…:         22:54                No. Luckily I have not ever encountered a polar bear and I would really like to keep it that way.

Katrina Jackson:            22:59                Okay. Wow. Yeah, that would’ve been a bummer to be taken out by a polar bear before getting to see the images.

Dani DellaGuist…:         23:07                Yeah. It’s just really bizarre when you spend years of your career getting ready to take images of something that you’ve never seen before. It really is an odd experience to have, and then you see it, and you’re overwhelmed. It’s so cool.

Katrina Jackson:            23:36                So when those images came back and you were safe and home from the polar bears, what was the most surprising thing that you ended up seeing with Bennu?

Dani DellaGuist…:         23:45                Yeah, so really early on some of the first images of Bennu that were returned looked so similar to asteroid Ryugu, which is the asteroid we were talking about earlier that was visited by the Hayabusa2 mission. And so at first we were like, “Oh, did we go to the wrong place?”

Katrina Jackson:            24:04                That would be an interesting mistake.

Dani DellaGuist…:         24:06                Yeah. But as we started getting a little closer to Bennu, we were all really, really surprised by the amount of rocks on its surface. But seeing those on Ryugu a couple months beforehand had prepared us for that possibility. So I think the thing that was truly surprising were these very, very bright rocks that were 10 times brighter than the background surface on Bennu that showed up in a couple of small places here and there, peppered throughout the asteroid.

Dani DellaGuist…:         24:40                And those were the rocks from Vesta that I mentioned earlier, but we weren’t expecting to see those, and they were just so much brighter than Bennu that they really looked like beacons on its surface when we were returning those initial images, they were pretty surprising. So that was pretty memorable, and one of the things that personally surprised me the most, because we hadn’t been prepared for that possibility. Seeing Ryugu a couple months before Bennu had sort of begun to mentally prepare us for a rockier than expected surface.

Dani DellaGuist…:         25:15                And I think just the overall feeling of seeing images come down where you’re getting closer and closer to the asteroid, you’re seeing details that you couldn’t see in earlier images, You might see a little rock and it looks funny, and the image just came down, you’re probably the first person in the team to see that image. And then you realize, “Well, I’m probably the first person in all of human history to see this little rock.” It’s a pretty cool feeling, getting to look at images of these distant worlds every day.

Vicky Thompson:           26:05                I can’t imagine being on the imaging team of one of these missions and getting to be the first person ever to see rocks on a different world. It does sound pretty cool.

Shane Hanlon:              26:14                Yeah, definitely. And I know we mentioned Vespa, no not Vespa, it’s not a scooter, Vesta. Yeah. So we mentioned Vesta a couple times. Katrina, what is Vesta?

Katrina Jackson:            26:26                Yes. So Vesta, not the scooter, is the name of a large asteroid in the main asteroid belt between Mars and Jupiter. And Vesta, it has a really distinct composition, and a while back Vesta must have been womped by a smaller asteroid because we find chunks of Vesta in all sorts of places. There are a lot of meteorites on Earth that we believe came from Vesta, and as Dani was telling me, apparently there are even chunks of Vesta on asteroid Bennu. And that’s one of the reasons why she doesn’t think Bennu is an extinct comet because in order to have crossed paths with the debris from Vesta way back when, Bennu had to have been in the asteroid belt with the other asteroids, and not in the outer solar system with the comets.

Vicky Thompson:           27:13                Okay. So asteroids smashing into each other and chunks flying through the solar system makes me think about the obvious. What if one of these asteroids hit Earth, or comet, or an extinct one?

Shane Hanlon:              27:26                Well, okay, so wait. Just to be clear, I have to pop in here, because I wasn’t thinking of Earth’s extinction when developing this series. That’s wasn’t on my mind, but we’re here now and I’m curious, so what about it?

Katrina Jackson:            27:44                Yeah. So Dani and I, we did get into that briefly. I asked her about whether the distinction between comets, asteroids and extinct comets makes any sort of difference in terms of planetary defense, like for planning a mission to deflect one of these objects to prevent it from hitting us.

Dani DellaGuist…:         28:06                Well, there’s a lot to unpack there. So I’ll just say that for a lot of the asteroids that we visited recently with spacecraft, they appear to be rubble piles, which means they’re very loosely, gravitationally-bound piles of rocky material. And for a comet, we might expect that to be a bit more consolidated because it would have that icy material that’s binding everything together.

Dani DellaGuist…:         28:40                We would want to understand the material properties to design the appropriate mitigation technique, and here’s a number of different mitigation techniques that have been theorized. But my preliminary thoughts are it would come down to how cohesively bound is the small body in the cometary case versus the asteroid rubble pile case.

Shane Hanlon:              29:16                I just had such a great time listening to this interview because Dani, frankly, is just so fricking impressive.

Katrina Jackson:            29:23                Yeah, she is. And actually since recording this interview, they announced that they’re going to be extending the OSIRIS-REx mission, and the new phase is going to be OSIRIS-Apex that’s visiting a different asteroid, and for that extended mission, Dani’s actually going to be the principal investigator. Which is really impressive. I think she’s going to be one of the youngest NASA principal investigators for a mission.

Vicky Thompson:           29:45                Very cool.

Shane Hanlon:              29:46                That’s super cool. And she has an asteroid named after her, right?

Katrina Jackson:            29:52                She does. I believe the number is 133744 DellaGuistina. And actually, fun fact, I have an asteroid named after myself, as well.

Vicky Thompson:           30:02                You do. What’s its name? What’s its number?

Katrina Jackson:            30:06                I made sure to look it up before the interview. My asteroid is 120352 Katrina Jackson.

Shane Hanlon:              30:14                And how does one get an asteroid named after themselves?

Katrina Jackson:            30:18                So basically, pretty much everyone involved with the OSIRIS-REx mission ended up getting an asteroid named after themselves. And I had worked as a video producer on some of the videos for OSIRIS-REx. So that was a cool reward that you don’t get with most other missions, getting something named after yourself.

Vicky Thompson:           30:36                That’s really neat.

Shane Hanlon:              30:38                Yeah, and I’m just going to apologize in advance that we at Third Pod can’t name an asteroid after you for your contributions with us.

Katrina Jackson:            30:46                Oh man.

Shane Hanlon:              30:47                But we very much appreciate it.

Katrina Jackson:            30:49                Okay.

Vicky Thompson:           30:51                If we could, we would.

Shane Hanlon:              30:53                If we could, we would. All right, folks. Well, that’s all from Third Pod from the Sun.

Vicky Thompson:           30:58                Thanks so much to Katrina for bringing us this story, and to Dani for sharing her work with us.

Shane Hanlon:              31:04                This episode was produced by Katrina with audio engineering from Codden Warren.

Vicky Thompson:           31:09                We’d love to hear your thoughts on the podcast. Please rate and review us, and you can find new episodes on your favorite podcasting app, or at thirdpodfromthesun.com.

Shane Hanlon:              31:18                Thanks all, and we’ll see you next week.

Shane Hanlon:              31:26                Well, I’m going to hit record. You don’t have to tell me about funny accents, my Western Pennsylvania made for this American life podcasting voice.

Vicky Thompson:           31:37                Do you say may-sure?

Shane Hanlon:              31:40                See, it’s hard. No, I say measure, but I say, “Oh, Kristen does really well.” I say “our and are” and I say “pool and pull.” I don’t differentiate words with vowels, what are those, homonyms?

Vicky Thompson:           31:55                Vowels?

Shane Hanlon:              31:56                No. What are the ones that sound the same but just spelled different? Homonyms. I’m really bad about they are the same word for me. So yeah, I’m bad with vowels. That’s that’s a great thing to be as a professional science communicator with their own podcast.


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