Chasing fireballs and the evolution of our solar system with Professor Gretchen Benedix

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We've spoken about indirect career paths, but Professor Gretchen Benedix calls hers the pinball method, starting on a course that could change direction when she strikes something that she'd like to delve more into. This method has served Gretchen well and has given her opportunities to work with Dr Sally Ride, the first American woman in space, chase fireballs over the desert, hunt meteorites in Antarctica, and even get an asteroid named after her.

Join us as we speak with Gretchen about her journey to astrogeology, discovering how the solar system evolved, and the Desert Fireball Network.

About Professor Gretchen Benedix

Gretchen Benedix is a Professor (and former Australian Research Council Future Fellow) in the School of Earth and Planetary Sciences at Curtin University. She is also a member of the Space Science and Technology Centre, the largest research group dedicated to Planetary Science in the southern hemisphere.

She is a fierce STEM and Women in Science advocate and takes her responsibility as a role model very seriously. She uses her work to inspire young people and pass along her passion for understanding our Solar System.

Gretchen's research interests lie in the study of meteorites to understand and unravel the evolution of the Solar System. She and her team are currently interested in using machine learning techniques to extend our ability to interact with big datasets, specifically looking at the numbers of craters on other planetary surfaces.

Gretchen wants to understand how the Earth fits into the history of the Solar System.

... And also, she love rocks...

Gretchen has a broad educational background in Geology, Engineering, and Physics, which lets her pull together multidisciplinary ideas to unravel the mysteries of the rocks.

She also loves science communication and has had the opportunity to work at two world-class museums as a planetary scientist, cosmic mineralogist, and astro-geologist, where Gretchen had the pleasure of sharing what she does --- It's just one of the many aspects of her job that she loves

  • to be able to get other people, especially young folks, excited about studying our solar system and our place in it.

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  • [00:01:38] How one gets an asteroid named after them.
  • [00:04:56] Gretchen's journey began in psychology.
  • [00:06:52] The transition from psychology to physics was not smooth sailing.
  • [00:08:29] The slow drift into space and getting hooked on rocks.
  • [00:11:35] The beauty of geology.
  • [00:16:19] Being flexible gives you the space to be open to opportunities.
  • [00:18:34] Looking to space because you can't look inside the Earth.
  • [00:22:41] Comparative planetology and looking at our system in context.
  • [00:26:49] Context and time scales.
  • [00:28:59] The engineering in space travel.
  • [00:32:48] The Desert Fireball Network.
  • [00:36:42] Location, location, location.
  • [00:38:31] Tying it back to their origins and the solar system.
  • [00:40:35] Meteorite families.
  • [00:43:47] Surprising learnings so far.
  • [00:46:47] The two-body problem.
Michele Ong

We've spoken about indirect career paths, but Professor Gretchen Benedix calls hers the pinball method, starting on a course that could change direction when she strikes something that she'd like to delve more into. This method has served Gretchen well and has given her the opportunity to work with Dr Sally Ride, the first American woman in space, chase fireballs over the desert, hunt meteorites in Antarctica, and even get an asteroid named after her.

Join us as we speak with Gretchen about her journey to astrogeology, discovering how the solar system evolved, and the Desert Fireball Network. I'm Michele Ong, and this is STEAM Powered.

Good morning Gretchen. Thank you so much for joining me today on STEAM Powered, I'm really looking forward to speaking with you about your incredible journey.

Gretchen Benedix

Thanks very much. I'm happy to be here and thanks for inviting me.

Michele Ong

Oh, it's an absolute pleasure. And you know, I really love this because your journey is wild and windy and it's great, I love it. Because you studied physics, then engineering, and then geology and geophysics. And now you're an astrogeologist finding out how the solar system evolved from rocks, which is very, very cool.

And, you've also been to Antarctica twice, hunting for asteroids, meteorites, sorry, and had an asteroid named after you, the asteroid 6579, for your contributions to the field. So that is so wild!

Gretchen Benedix

Yeah.

How one gets an asteroid named after them.

Michele Ong

Before we get on with your journey, I want to know, how does one get an asteroid named after them?

Gretchen Benedix

Uh, so the asteroids are discovered by astronomers. So they do these, you know, massive telescope discovery programs, then the discoverers have the right to name them. And so the original asteroids were, you know, if you look at the first sort of hundred or 200 asteroids, they're all minor Greek deities, pretty much. So it's like, you know, number one was Ceres, and one is Pallas, and number 16 is Psyche, and Eros is in there. So there's, there's a bunch and that probably actually goes into like the thousands.

Michele Ong

There's a lot of them.

Gretchen Benedix

There's a lot of them, but then we get to the point where we're kind of running out of the Greek names. So then it kind of goes to, well, well, now what? So then it starts being, I think the Beatles all have asteroids named after them.

It's sort of whatever the discoverer felt like. You know, I feel like these asteroids should get these names. So the way this kind of came about is that it turned out that a friend of mine who was very much involved in the asteroid/meteorite connection, suggested to someone he was working with very closely who was a discoverer.

He was like, well, you know, next time you, you put in for asteroid names, what, what do you think of this as an option? And so that's kind of how it came about. And then the International Astronomical Union, which is the body that kind of is in charge of naming other planetary objects was like, yeah, yeah, that's cool.

And so every couple of years we go through who's been doing meteoritics, who's been doing planetary science, who's been doing like that, and then kind of a whole trench of people get asteroids named after them. So my partner has one, last year, a bunch of our early careers got asteroids named after them.

Michele Ong

Oh, that's so cool!

Gretchen Benedix

Yeah. it's one of those, like you got to kind of know the person kind of, or be in the vicinity of someone who knows the person. And, and so that's kind of how it came about, but yeah, if you go and look, there's all kinds of, uh, naming rules for planetary bodies. So you can check it out for every single planetary body. They have rules around what things can be named.

Michele Ong

Is awesome and very, very cool. Yeah, because it did feel like for a while there that it was, Yep, I just feel like this today. No, but it's great. It's so cool. And I love that your partner's one is also sequential as well, which is very cool.

Gretchen Benedix

Which is interesting. Yeah, I mean, we were together at the time, but I'm not 100 percent sure they meant to do that, but I'm okay with it. And mine's bigger than his, just --

Michele Ong

Just saying.

Gretchen Benedix

I'm saying. But neither them is anywhere, you know, is not potentially hazardous is not ever to get close to the Earth, which is a little bit sad, but you know, it'd be nice to see it. Yeah. I'm like, I wonder if the Psyche spacecraft could like fly past it.

Michele Ong

Just a little detour is fine.

Gretchen Benedix

That takes lots of planning.

Michele Ong

It does. It's all good. Cool.

Gretchen's journey began in psychology.

Michele Ong

So, rewind again and go back to the start of your journey. And you started off in physics. So, what drew you to physics?

Gretchen Benedix

Well, what actually happened was I started in psychology. So, in the US when you go to university, it's a different system because they give you a lot more electives at the beginning. Uh, so it's a four year program and you can declare a major going in, so you can say, I want a Bachelor of Arts in this major.

And so they'll kind of set up your timetable to accommodate that. But you have to spend a whole bunch of time taking all these electives. So, I didn't have any psych classes on my timetable in the first term. So, I had elective space and I had to fill that. So, I took an astronomy unit and it was, you know, baby astronomy.

But they took us up to, um, so I did my undergrad at UC Santa Cruz in California, and they have an association with an observatory in the San Jose mountain area called Lick Observatory. So it's one of the really old observatories, but they took us up there on a field trip and they let us look through the telescope and I got to see Saturn and it was like one of these weird kind of moments of, is that real, or is that just a picture at the end of the telescope? Because it, it was Saturn, but it was like the pictures of Saturn that we all see. But, it's so weird, because when you look out at night with your eyes, you can see a big bright light, and you can go, Oh yeah, that's a big bright light, woo.

Um, but then you take this telescope, and you see the rings, and it looks like everything you've ever seen it look like and you're like, that's weird. So it was at that point I was toying with the idea of astrophysics because that was a really big area of study at Santa Cruz.

The transition from psychology to physics was not smooth sailing.

Gretchen Benedix

So I switched to physics, which obviously you do when you're starting in psychology. Totally reasonable. Uh, struggled. I did not, it was not acing everything. I struggled. I took classes multiple times. You know, it's, it, yeah, I, I had a hard time sometimes. But at the end of the day, it was kind of, I got these opportunities for internships to work with research groups, and so one of them was working with particle physics.

And so that actually really sparked an interest in chemistry because particle physics is all about the, the base particles and like how do they interact with each other. So I did a bachelor's research thesis on a couple of particles and basically that kind of interaction and that kind of experience is what sort of said, Oh, research is interesting, but in my head, I had no plan to do a Master's degree, I had no plan to do a PhD. I am very much a, um, it's the pinball machine mechanism. So, you bounce off of a thing and go a new direction.

And so, I was thinking I'd do something with particle physics, and then when I was about to finish, I wasn't sure what I was going to do. I was just going to 'go get a job'. I don't know what I'm going to do, but I, I knew I didn't really want to do a postgrad degree in particle physics because I was-- I didn't have enough confidence to think I'd pass the tests to get into a postgrad degree.

The slow drift into space and getting hooked on rocks.

Gretchen Benedix

But I did another internship with a group in San Diego where I ended up working really closely with some space people who were looking at planetary and solar system space. And one of the opportunities I got in that internship was to actually help Sally Ride, who was the first US woman astronaut, who was at that time a physics professor at UC San Diego. I got to help her pull together material for a lecture that she was going to give on living in space.

And so, she and I are sitting next to each other and she's got these videos that she took while she was in the space shuttle. And we're cutting them together and she's saying, Oh, that goes there and I'm, I'm going, Oh, okay. Yeah. Cool. You're Sally Ride. Okay, cool. Um, very interesting. Very, very nice.

And so, the, the group around that was very interested in planetary science and doing planetary related things. And so I did that first internship. Then I had a second internship that kind of led into doing a Master's degree there. And so the second internship was actually trying to catalog and do a statistical analysis of the number of what we now call potentially hazardous asteroids.

So we were looking at those asteroids that have the possibility of crossing the Earth's orbit at some point. And at that point, we have observed 130 asteroids that fit this category and we now have a lot more . You know, this was 30 years ago, but over the course of 30 years, our observational techniques have just gone crazy.

So that was where I kind of started on the asteroid tour, and then I moved into my Master's degree. So that was an engineering degree, but it was really a combined planetary and physics-- particle physics because I was doing experiments to try and simulate the solar wind hitting the surface of an asteroid.

And so you, you have a particle beam and you're firing a beam of hydrogen atoms, ions, hydrogen. I think I'm pretty sure it was hydrogen, not helium. Yeah, it was hydrogen. And, and then it was like hitting a piece of rock that was supposed to simulate the surface of a, an asteroid and so I did that and I got a Master's out of that and as I was doing that, the pinball machine occurred again because I was looking at the rocks and the rocks were like, oh, well, they're really pretty.

But I was, I just felt like out of my depth from a geology perspective. It sounded, you know, it was really cool, I liked it. And I was doing all the chemistry and trying to figure that out. So I took the basic geology course at UC San Diego and then I took their mineralogy course and I was just hooked immediately.

The beauty of geology.

Gretchen Benedix

It was like so different from physics where you kind of have to imagine, where with geology, you can pick up a rock and you can actually start to make an inference based on what you can see. You can look at it and go, well, this is, you know, coarse grained or fine grained, or it's this color or it's that color.

So right off the bat, you have information and you're not sitting there going, well, did the electron hit the thing? Did it bump the thing mathematically? What am I looking for? So it was very visual. And then I had the opportunity, once I finished my Master's, I was deciding between whether to go and stay with astronomy and do more asteroid science in a PhD or to try and do the meteorite side and the geology side.

And so I ended up going and doing the geology side. So that is kind of the very. Windy road. And then once I had my PhD, I also had multiple fixed term contracts. Basically we call them postdoctoral fellowships. So I had one, two, I had probably four of those before I got a permanent position. But for my personality, I'm fine with wandering. So I didn't have a problem with that. And I didn't, you know, I had longterm, I had relationships during all of that that we're always long distance. And I was just like, yeah, right, fine. That's how it goes. So, that's just, I think, part of my personality is, I'm okay with that.

Michele Ong

So, all the internships and the programs that you were in, were they also kind of pinball, or did they just happen? Did you choose specific topics for reasons?

Gretchen Benedix

It's more pinball again, and accidental. and, so the first internship, the physics internship was at UC Santa Cruz. They had a connection with the Stanford Linear Accelerator Center. They were really trying to diversify. So they were trying to make sure that underrepresented folks would get an experience, and so they had a very specific internship program targeted. And a lot of our faculty, a lot of our staff were staff at Stanford, like co, co badged. And so there was a really, like, you should, you know, give this a go, see what happens and apply for it. And so I applied for it and I got it. And so it was like, Oh, well, this is great.

It really was, you know, I, I don't think I was exactly what they thought I was when I got there, but I ended up getting information for them that was useful and, you know, I wasn't able to program a Monte Carlo, you know, simulation of particles, but I was able to digitise a whole bunch of Information that helps those models.

And so, while it was not necessarily glamorous, the fact is that it was like, I'm sitting here at Stanford University, I'm able to go and see the accelerator, see the detector system, start to see that, make those connections between, this is how these particles, like, smash together, and what we're looking at is recreating things that happened at the Big Bang.

And so it's, you know, very, very cool. So it was, it was a fortuitous opportunity that was advertised. And the school I went to, we had a very small physics department, like in terms of student base, right? You know, everybody has to take physics in their first two years because every, undergrad major needs physics and math.

So those classes are jammed, but as we went up, I think when we graduate, I was the only female graduating from my class, but I think we only had about six people.

Michele Ong

So still a very small cohort anyway.

Gretchen Benedix

It was a really small cohort. Yeah.

So it was, it was kind of that. And then the other two were also kind of, because my partner at the time was going to these places and I was like, no, I got nothing to do. So I kind of tagged along and, and these internship opportunities arose partly because he was in that space already. And so he kind of was paving that way. So there was kind of a ally kind of, you know, here are these things and I'm like, yeah, sure, fine, whatever.

I mean, I did do some interviews to get jobs after my Master's and I was just like, no, I'm good.

Michele Ong

Nothing really took your fancy.

Gretchen Benedix

I'm good. Research is fun.

Being flexible gives you the space to be open to opportunities.

Michele Ong

Yeah. And the thing is that all the opportunities that you had is because of that pinball approach. You were more open to the idea of trying things rather than having a set focus on, I need to be on this track, which, you know, it, it, for some people works amazing, but it gives you that opportunity to at least explore outside what you originally or would normally feel comfortable doing. And it's so cool.

Gretchen Benedix

Yeah. Well, it's, it's good and I do advocate for being flexible and being able to react to a situation or an opportunity that you might not have thought of. But you know, especially if it's a short term opportunity like an internship, do it, because it teaches you and it gives you the experience of that particular area and environment and you start to learn things from that. And the more you do that, the more you just gain that experience that then makes things, you know, you can start to be quite broad in your thinking.

I mean, it took me a long time, even after my PhD to be able to think really big picture, and I'm always learning, but I remember, when I first started my PhD, I was focused on these very specific things of my PhD.

And then as I went along, kind of three or four years after my PhD, I was like, well, yeah, I'm not going to study this type of rock the whole time, but the skill set that I got to understand this particular set of rocks is applicable to this set of rocks, and this set of rocks, this set of rocks, and then once you have that kind of broad base of, oh, well, these act like this, then you're starting to see the whole picture of the solar system and you're going, oh, well, these rocks look like this and they seem to be mostly here.

And then you're starting to kind of build that big picture, but you can't do that like straight out of the box.

Michele Ong

No, because you don't have the perspective to be able to understand that there is a much bigger picture out there.

Gretchen Benedix

Yeah, exactly. You need those baby steps to kind of build that up. And then the days that you kind of go, Oh, those are connected like that are really, really great days.

Michele Ong

Oh yeah, absolutely. And now you're doing super big picture with evolution of the solar system.

Looking to space because you can't look inside the Earth.

Michele Ong

But did you ever consider bringing your focus on rocks back to Earth? Or was it always, I need to see what's happening out there?

Gretchen Benedix

Well, I did my PhD in Hawaii. So from the Earth rock perspective, volcanoes were always the kind of thing. So I'm a big fan of that. We do a lot of work with analogs. So when, you know, humans don't go to Mars, and humans haven't been to the moon in quite a while, and so what we have is a lot of imagery and we can make inference based on that.

And so we can then find areas on Earth that look similar, and then we can start to use that information to see if that explains other areas. But I was mostly focused on the rocks that don't have an Earth equivalent. They're kind of the things that talk about how did the Earth actually differentiate into a core mantle and crust?

So it's something that happens really, really early on. And when I took my first geology unit, what we were taught was that a whole bunch of rocks that were not pre-melted so they were what we call super-primitive, hadn't melted, they all smashed together and over time that heats things up and then at some point, and I think they actually called it this, at some point, it's hot enough that all the iron melts and sinks to the middle. And that is called the iron catastrophe. And we now think, and it's partly due to some of the work I've done, or some of the meteorites I've looked at, and some of the other meteorites that we have in our collections, we now think that those early asteroids actually were melting along the way.

And so when it was all smashing together, it was, it wasn't like two hard rocks smashing together and then over time that heats up. It was a combination of, they were already warm, they were sticking, they were already separating, and then you kind of build that. So it kind of is I'm looking at the rocks from outer space because I can't look at the rocks in the interior of the Earth.

And it's giving us a starting point, and it's giving us snapshots of processes. And so this would help us understand Earth, it would help us understand Venus, it would help us understand Mars interior-wise, and we don't have the same level of access to the interior on those planets that we do on Earth.

So it's always kind of mixing and matching.

The other thing is that sometimes it's easier to look at the surfaces of other planets, rather than look at the surface of Earth with the spectral kind of, you know, the way we look is by looking at various wavelengths of the electromagnetic spectrum.

So visually You know, we see stuff, but if we can go outside of that range, we can actually start to understand things like mineralogy and features of the rocks. Like, is it coarse grained? Is it fine grained? Is it solid? Or is it, is it sand? You know, you can get all kinds of interesting information.

But with Earth, when we try to do that from space, it's actually really hard because Earth has this fabulous atmosphere and it causes all kinds of, it wreaks all kinds of havoc when you're trying to kind of make those, those connections.

Michele Ong

Because it adds so many extra factors to the way that it interacts, the reactions, chemical--

Gretchen Benedix

Exactly. Exactly. And it absorbs more of the wavelength, so then you miss out on things that are critical to be seen. There are new-- JPL just a couple of months ago, just released a map, mineralogy map of really arid regions of the Earth based on satellite data, which is amazing because normally the way we would figure out those mineralogies is a wavelength range that is completely absorbed by the Earth's atmosphere. So this is a satellite way to look globally for these signatures and it has to do with, you know, critical minerals, and resources, and whatnot.

Comparative planetology and looking at our system in context.

Gretchen Benedix

Um, , uh, but the other thing is that you always have the opportunity to compare. So comparative planetology is really interesting because the Earth is almost unique in the solar system, in how it's evolved post initial accretion and differentiation.

So, most of the planets all started kind of that same way, but then something happened over time and they, they all have achieved different states later on. We only recently in the last maybe 25, 30 years have realised that, you know, Jupiter, we knew that Jupiter forms first. But we didn't realise that Jupiter formed roughly, or what we think based on models, Jupiter formed roughly where it is now in its orbit, but it took a little stroll and kind of wandered into the inner solar system, which is why there's not a planet between Mars and Jupiter, because it screwed up, gravitationally, it screwed up what would have been the kind of point where you could start smashing those things together and growing a planet. And it's probably why Mars is smaller than Earth. Because Venus and Earth are about the same size.

Mercury is just too close to the Sun. And we're not sure, but there's also an idea that it lost a lot of crust, because we can get information about what the interior is kind of distributed like based on how planets interact with each other at really high number of decimal places in maths. And then you can say, oh, well, that's because this looks like this. So based on that, and based on some, some spacecraft data, we think Mercury has a really big mantle compared to its crust, even more so than Earth. So something happened there. So it's like the four inner planets, Venus and the Earth are the same. So we think that Mars and Mercury probably could have been the same, like as big, but this Jupiter thing causes Mars to kinda miss out, which then causes Mars to lose its atmosphere 'cause it's too little to hang onto it.

And then you go out to the outer solar system and things are just like, oh, it's cold. We're just going to condense all the ice and we're just going to stick it all out there. It'll be fine. And then the asteroid belt is just because Jupiter did its little thing. And it was only because Saturn was like, Jupiter, come back. Come back. You wandered in too close. All right, I'll come in and I'll help you come back. So there was like this weird Jupiter-Saturn dance that created things, gravitationally as well.

So it's that kind of stuff. It's like we look at the Earth and we go, okay, it looks like this, but why? But then we can kind of fit all these things together to say, okay, Earth looks different for a reason.

It's in a really good spot in our solar system first, but it could have actually been Mars was the better spot, and because Jupiter did its little stroll, Sunday stroll, yeah, then we kind of get the Earth as kind of the sweet spot. Yeah.

And then it's like, you know, there's a moon of Saturn called Titan, which has almost the same atmosphere as Earth, but because it's so far out, it's kind of got a slightly different-- so it's got a very nitrogen rich atmosphere.

But it doesn't have the same level of oxygen associated with it, so it's got a lot of methane, it might have methane rivers, it might have methane lakes. So that's kind of on the radar for the space exploration is, let's go to Titan and see what we can see about habitability. all of this kind of fits together to figure out why is the Earth the way it is.

Michele Ong

Yeah, and it adds so much extra context because you're not looking at them in isolation anymore, you're looking at them again in terms of proximity, in terms of the conditions, in terms of What the distance does, and what Sunday strolls do to everyone else.

Context and time scales.

Gretchen Benedix

Exactly. It's all about the connections, right, and it's like, you know, even in the galaxy, the solar system is, in a particular arm of the galaxy, but it's actually orbiting the centre of the galaxy, so that means that every so often we're in a different, I mean, we're always in a different part of space, but it comes around, but it's like, there's a 250 million year orbit there, so, you know, we're never going to experience the full orbit, but the earth has experienced that full orbit, uh, 16 and a half times, or 17 times. But we don't know, like--

Michele Ong

What happens when it hits those particular points?

Gretchen Benedix

And geology is amazing on Earth because we can actually start to see, well, are there cyclical signals that we can see that happen on a time scale of 250 million years. And maybe that if we tracked where we might be during, maybe that is something that occurs during that timeframe, the solar system experiences a strange cloud of stuff. It's like when we go through our cometary tails and we get meteors. Maybe we go through some weird planetary destruction area and it just breaks everything.

Michele Ong

Because it's all about scale, because yeah, as you said, it's like we're seeing it in one perspective, one particular scale, but then in the wider scheme of the solar system, the same things are happening, but bigger.

Gretchen Benedix

Yeah, over a longer timescale that we can't recognise. And I think that's one of the things that's also really cool and also really mind blowing about the solar system, the galaxy, the universe, is how big, how far away, and how, Just vast space is, and, we get, we get kind of complacent cause it's like, oh, well the movies show that we're in an asteroid belt and we have to bob and weave and dodge.

And it's like, no, no, no, no, no. We have to actually target those things. If we just fly through, we're just flying through. We're not going to accidentally hit anything.

The engineering in space travel.

Gretchen Benedix

There's a mission that's going to, it's called Lucy, and it's a mission that is, the spacecraft is visiting, I think it's like nine asteroids-- so part of the orbital thing means you get these weird resonances, so there's these resonances in Jupiter's orbit where a whole bunch of rocks exist in front, in that orbit line, and in back, and so this Lucy mission is going to actually kind of swing between these two populations of rocks, and these particular rocks are thought to be the most primitive materials that everything else was built from, but the engineering involved in spacecraft to fly from here to here to here to here without a gas station out there, because you're not refilling, right?

You have to rely completely on, you know, how gravity, and that stuff is amazing to me. I'm just like, you know, how engineers can plan out a mission that is going to be 10 years, you know, you're not going to get to things until potentially 10 years later. You hit the mark, you're like right on target.

And the fact that we still talk to the Voyager satellite, Voyager 2, we still talk to it. It's been flying for 40 some odd years. And we still talk to it every day when, when it's not pointing the wrong way. And then when it points the wrong way, we find a way to bombard it with signal to say, no, no, no, we're over here.

Michele Ong

Yeah. The science and engineering and just all the different literal moving parts to get craft out there on projects which are lifelong endeavours. These are whole careers long kind of projects and it's just phenomenal to think about that kind of scale.

Gretchen Benedix

Yeah, exactly. It's, it's absolutely amazing. And, and how we keep like the things that we do to improve and then go back and have a look, like, I don't know if you've seen the latest image of Jupiter from the Juno mission. I mean, just the detail of what we're now being able to see through some of that upper, upper atmosphere just shows Jupiter in a completely different way.

You know, we normally think of it with the bands and everything, and you start to look at this, and it's got like weird cells, and it just looks really, really interesting.

Michele Ong

That is awesome. Is there anything that you can kind of infer from the visual imagery or is that still not quite where you need it to be yet?

Gretchen Benedix

Not me, but there are other people who can. So a lot more atmospheric scientists deal with, sort of, the Jupiter side of things. I'm more hard rocky type stuff and trying to kind of look at how does the rock and the atmosphere interact sometimes. But atmosphere is such an interesting area. And I mean, our climate is absolutely an example of how atmosphere is very interesting.

But those, Jupiter and Saturn with their, I mean, just bizarre storms and things, people, not me can actually infer things from that imagery and start to say, oh, well, that's equivalent of this. It could be temperature shifts. It could be pressure variations. It could be all kinds of interesting things that might be happening.

So it's amazing what we can learn from just looking at a thing.

Michele Ong

Absolutely.

The Desert Fireball Network.

Michele Ong

So one of the reasons that you are in this part of the world is the Desert Fireball Network and being able to chase literal fireballs, which is very, very cool. So what is the Desert Fireball Network and how does it help you to figure out how the solar system evolved?

Gretchen Benedix

So we often want to know where we're from, right? As humans, we interact with each other and say, Oh, where are you from? Where'd you come from? Where were you born? What the Desert Fireball Network, in a nutshell, does is it allows us to figure out where meteorites were born.

And when we know where a rock is from, that gives us a much better handle on the whole system. So we have, we have a bunch of meteorites, right? We have something like 75,000 meteorites in the world's collections. And they have a variety of compositions, and we categorise them into families, and we think about them in terms of, you know, what does this mean for this unknown body, and so sometimes we're like, Oh, well, that's really, Oh, this could be really cool. This says something about this and we're learning about, you know, planetary differentiation, but we're focused on this one meteorite. And so it's not the most massive picture. So context and connection again, is where the Desert Fireball Network comes in is that it allows us---

So the Desert Fireball Network is, it is a system of cameras that are autonomous, so the engineering in this is amazing. So they're autonomously set into the desert, in the Nullarbor Desert and some in South Australia, but we've actually expanded it. So we call it the Global Fireball Observatory now. And so they, we've got participants with their own cameras in Canada, in the UK, in Morocco, in France, and I can't remember where else. But the team then, the idea is that if you have a camera that can take a picture of the night sky, and we've all seen those beautiful images of star trails when you leave a camera open at night.

You see those beautiful star trails. Well, if you have a meteor or what we call a fireball, which is a bigger meteor, it will leave a track behind it. Now, the trick is that there have been camera networks before set up, but they were set up in places where it was hard to retrieve when you found something, and there's a lot of maths that goes into figuring out where something fell, because it doesn't stay a fireball, right?

If it stayed a fireball to the ground, Earth would not be a happy place. It stops being a fireball at a certain elevation, which is good. Yay. And then it just drops. So there's a lot of maths that goes into figuring out how do we figure out roughly where it fell. But also, in order to really track where it's falling, you really need to have a good understanding of how fast it was going.

And so you need a way to look at time. And so, there's a whole bunch of engineering that goes into these images. Yay, they're there. But now we have this timer in it as well. So then we can see from that fireball image, how fast it was moving across that part of the sky. That lets us kind of figure out, okay, when the light turned off and then it's just falling under gravity, what happened, but we, that's not it because it's not just gravity, there's also atmosphere involved.

So what happens if it's windy out there? Does that like pull it off course? So huge amounts of like, behind the scenes. So you see a fireball, and behind the scenes all of this occurs to try and figure out where's a good place to go look.

Location, location, location.

Gretchen Benedix

So Australia is beautiful for looking because it's geologically very quiet.

In that we don't have active volcanism, we don't have major earthquake issues, we don't have a bunch of vegetation or wheat fields in those areas, so the places they had set it up, cameras before, they set cameras up in Europe, basically centred in sort of Czech Republic and Germany, Austria area, and basically anything that falls in that area falls into a giant forest.

Never gonna find it.

Michele Ong

So it's all, it's either densely populated urban areas or densely populated forest.

Gretchen Benedix

Exactly. And in the US they set it up in the Midwest thinking, Oh, this would be great. And it turns out cornfields are really hard to search. So, and, and the other place was Canada and they still have them in Canada, and some of our GFO are in Canada, and the, the possibility of getting the data fast helps us find it.

But in Canada, if you see something fall, depending on the time of year, you're either going to be hitting tundra, big old ice area, or, you know, marsh kind of things. And then, you know, forest and yeah, so the searching was tough. So the DFN really set the scene for how do you do this autonomously. The cameras operate by themselves, they have solar panels, they have comms, so they call us when they've seen a fireball, and then the team here has really worked out the automation of figuring out, all right, we've got this on a number of cameras, which really helps us figure out what is that trajectory look like, where is it gonna fall, are we in an area that we think we could go search, or is it a spider infested area that we're just going to say that meteorite can stay there.

Tying it back to their origins and the solar system.

Gretchen Benedix

But then we have a meteorite associated with a fireball. We have a fireball that allows us to track where in the solar system, it came from, which then we haven't tied them to specific asteroids yet but we have tied them to regions in the asteroid belt.

And so it's all about where did it come from because that helps us really understand how did the solar system vary over time, and does that have an effect? Can we see variation that affects the Earth based on that?

So, and it's been super successful, before the DFN started, I think there were about eight meteorites that had orbits and three of those were from previous camera networks.

The others were fortuitous, like historical, or there was one meteorite that fell in 1992 that was videoed by a whole bunch of people because it happened on a Friday night on the east coast of the US when everybody's at a football game. Well, it's like massive. So we got it, you know, we got the trajectory from about five or ten different states and angles, and then we actually had the meteorite the next day. So we knew everything worked together for that one. And so there have been a couple that have been like that. But since we've come online, we've gotten, I think we've gotten 10 over the 10 years we've been working. So that previous number was over about 40 years.

So we've gotten at least 10 and we know there are more on the ground that we haven't picked up yet, but we also kind of were the start of the new wave of camera networks. And so, some of our colleagues have set up other camera networks and then we've got more coming. So we're now up to about 40 meteorites that have orbits, which builds our confidence in our understanding of the compositional variation throughout the solar system.

Meteorite families.

Michele Ong

With all of the ones that have been found so far, you been able to link any of them together as coming from the same body?

Gretchen Benedix

Yeah, so a lot of meteorites that we get here on earth are what we term ordinary chondrites and, ordinary being the operative term there. So most of what we see, most of the population of stuff hitting the Earth now comes from probably three or four bodies that collided and broke up. Probably, I don't, I can't remember cosmic ray exposure ages right now, so there's a way we can tell, and it's like tens of millions of years ago this occurred, and then it's what's kind of driving the current population, but it's not, all that.

We can tell meteorites that come from the same parent. So we have what we call DNA for rocks, which is oxygen isotopic composition. So basically oxygen has different numbers of neutrons, same number of protons because we all know how chemistry works and the number of protons defines the element.

So it's oxygen, but it has a bunch of neutrons and it can change the number of neutrons it has based on a whole bunch of different factors, but throughout the solar system, we can see that there's variation in the two smallest ones, or the two least abundant. And so, we can actually use that to group meteorites.

And we found a secondary one that fits that, so now we have two ways to kind of really find families. And so that works for rocks that have oxygen in them. Sometimes meteorites are mostly metallic and don't have any oxygen. So then we have to find other ways to find families. But basically doing that, we think that the two biggest groups probably come from three to four, or maybe five bodies that were very similar. There's a whole bunch of one group that we think comes from the asteroid 4 Vesta because of what they look like spectrally and what Vesta looks like spectrally. And so we've got more information about that based on a mission that went and orbited Vesta for several years.

And then we have a bunch of groups that we don't have a specific body, but we know they have to be different bodies. So the, the iron meteorites that we have, we think they represent probably 13 different differentiated asteroids, and then there's a whole bunch that don't fit into those groups.

And so they could potentially be bits and pieces of another hundred different asteroids. And then we've got some from Mars and we've got some from the moon. And then there are a few other bodies. So we think, we don't know exactly which body, but we know they're related. So when we look at them here on earth, we go, Oh, well, these, these are related and we'll put together and we'll figure out how they, how they, work.

Michele Ong

That's cool.

Surprising learnings so far.

Michele Ong

So, what is the most unexpected thing that you've learned so far in doing all of this?

Gretchen Benedix

That's a good question. Um, well, all of it, because I didn't know it beforehand.

Michele Ong

Good answer.

Gretchen Benedix

Uh, I think at this stage, nothing is too surprising. I know that's probably not what we want to talk about. But I think, actually, I think in terms of kind of habitability studies, I think it has been really surprising to see the evolution of how the surface of Mars has gone from being like, when I first started, Mars was like, Oh, it's dry. It's dry. It's dry. It's dry. And then there was this meteorite that had been found in Antarctica that was initially not thought to be from Mars, but then was found to be from Mars through the oxygen family thing. And then somebody did some really high resolution imaging and they did chemistry and it was thought to potentially contain evidence of extinct life in it.

And so that has kind of opened up this whole area of trying to understand how geology and life and biology, how do they all connect up? And does it mean that there were areas of Mars that would have been habitable? And then that kind of evolution of looking at Mars and going from it being a dry, desolate, desert planet to, well, yes, now, but probably in the past, you know, based on what we can see when we look at it, it looks like it had a lot of water on it, and it looks like that water flowed everywhere.

So I think that might be an interesting one for me to look at that habitability, and that, you know, we have the other thing is looking at Europa and Titan in terms of those habitability things like, the moon, Europa probably has a larger abundance of liquid water in it than the Earth does, which is--

Michele Ong

That, that's a lot.

Gretchen Benedix

Yeah, I mean the Earth's, the amount of water on the Earth's ocean, because the Earth is so huge and the ocean is like right at the top, and there's going to be water throughout, but when you just, even though Europa is so much smaller, it's really, it's concentrated everywhere, plus it's got this massive ice sheet as well.

So, just looking at that, kind of, those kinds of things are quite interesting and surprising and things that definitely would be fun to learn more about.

Michele Ong

Yeah. Because there's so much potential there.

Gretchen Benedix

Exactly.

Michele Ong

Very cool. So we might start to wrap up now so I can let you get on with your day.

The two-body problem.

Michele Ong

But one thing that I did want to mention, which I mentioned to you before, is when I've spoken to a lot of other researchers and academics, they've brought up the two-body problem and the two-body problem is when you've got two people who are very skilled in very specific things and they end up having to move between places for their work and how you balance that problem.

Because of the amount of travel you have had to do for your own career, and because your partner is in a similar space, how have you navigated the two-body problem?

Gretchen Benedix

The two-body problem is real. I think it's gotten better. I think, I think that academic institutions have started to realise that you can't really just go with one without the other. And so it is getting better, but it is something that is still a big problem in that oftentimes there are not two jobs at the same place, or there aren't enough institutions in an area that could accommodate two people.

The balancing act is around how do you decide what you're going to do? Do you, who compromises first? Who, who follows the other one? How much time do you want to spend doing the long distance thing? Those are all kinds of parts of the equation that come into it.

It's much easier to have that conversation when you don't have children. It becomes harder when there are children and you want to kind of create a sense of stability. But prior to that, it's very personality driven and are you okay with being in different places for an amount of time?

So that's the main kind of, you know, agreement that needs to be made, is coming up with that compromise. So when, my partner and I were first dating, because we were based on two different continents, we had the rule of when we did visit, it was for a minimum of two weeks, so it wasn't going to be a weekend turn-around.

It wasn't going to be a fly-in-fly-out. It was going to be, you know, a protracted amount of time to make sure there was a connection, you could keep the connection, and then, yes, you had to go back to work in your respective areas, but academics does add a level of flexibility because you do have the ability to work away from an office sometimes.

And so that was kind of how we balanced when we first started dating because yeah, continental relationships or multi continental relationships are a bit much.

Michele Ong

Challenging.

Gretchen Benedix

Haha! A bit of a challenge. Just the airfare.

Michele Ong

Just the airfare alone, my goodness.

Gretchen Benedix

Man. Ugh. Yeah, so it was tough and then we got very, very lucky because there were two institutions down the street from each other that were both happened to have someone doing something roughly in our expertise areas and so we were able to make it work like that and that was really helpful.

Michele Ong

That's very, very cool. Yeah! It's a tough sort of thing, especially like, similar areas, you have to find spaces, well, I guess on the upside, you're in a similar enough area that if you're going to a place, odds are they're also focussed in that particular area.

Gretchen Benedix

Yeah. But oftentimes they don't have enough money for two jobs, they only have enough for one.

Michele Ong

Yep. Oh well. But you've made it work now and you're doing awesome and both of you are doing absolutely awesome in helping to evolve and develop the research and space area in Western Australia, which is very cool. They're very happy about that. So, well, thank you so much, Gretchen. It's been amazing speaking with you about your pinball journey, which is very exciting and just full of exploration in, you know, academically, in your own work, and in space. So if people would like to know more about the kind of work that you do, where can they go?

Gretchen Benedix

I have a LinkedIn page, so that's where I usually do things. I also have an Instagram, I don't post much there, but it is there. So occasionally I'll stick some things in there that are spacey related. Um, I end up doing outreach events. So, for instance, I'm going to be speaking about the moon at the WA Museum in June, I believe.

Um, so that's another place people can find me. I'm at Curtin so you can always, you can Google me and find the things.

Michele Ong

Yep, absolutely. Alright, well, thank you again so much. This has been absolutely wonderful. And I hope you have an amazing rest of your day.

Gretchen Benedix

Thank you so much. Really lovely chatting with you, Michele.

Michele Ong

Absolutely wonderful chatting with you too.

Gretchen Benedix

Cheers.

Michele Ong

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