LISTEN: https://soundcloud.com/astrophiz/astrophiz-234-dr-jacob-parrott-mars-solar-storm
In May 2024, while Earth was treated to spectacular auroras, a much more violent story was unfolding 225 million kilometers away. A once-in-a-generation solar superstorm slammed into the Red Planet, providing a rare opportunity to study how a world without a magnetic shield survives a direct hit from the sun. In this episode of Astrophiz, we sit down with Dr. Jacob Parrott, a leading Radio Scientist at the European Space Agency (ESA), to discuss his team’s groundbreaking research recently published in Nature Communications.
Dr. Parrott reveals how he “hacked” two veteran spacecraft—Mars Express and the ExoMars Trace Gas Orbiter (TGO)—to perform an unintended cosmic dance. By repurposing redundant communications hardware, Jacob and his team used mutual radio occultation to peer into the Martian ionosphere during the “Mother’s Day Storm.” From his early days as a media intern at the European Astronaut Centre to his current work at ESA’s Space Research and Technology Centre (ESTEC), Jacob shares the “MacGyver-like” ingenuity required to turn communication tools into deep-space sensors, revealing the high-stakes physics of Martian aeronomy and the survival of planetary atmospheres.
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TRANSCRIPT:
Brendan: Welcome to Astrophiz. I’m Brendan O’Brien and we acknowledge the traditional owners of this land and their ancient astronomical heritage. Join us as we fight for a greener future and sit down with the world’s leading space scientists to see how our universe works.
And right now let’s speak with an amazing Radio Scientist from ESA, the European Space Agency, who gets satellites orbiting Mars to do impossible things.
Let’s zoom over eight time zones to speak with him.
Here we go.
Brendan: Hello, Jacob.
Jacob: Hi, Brendan.
Brendan: And hello, listeners. In May 2024, our sun unleashed a once-in-a-generation eruptive event that set Earth’s atmosphere ablaze with colour. But while we were captivated by the view from the ground, a much more violent story was unfolding 225 million kilometres away. Today we go inside that story with Dr Jacob Parrott joining us from ESA, the European Space Agency Space Research and Technology Centre in the Netherlands.
Jacob is a powerhouse in Radio Science, leading the charge in deciphering the data from our fleet of Mars orbiters. Now, his work gives us a front row seat to the Mother’s Day storm, the devastating impact on a world without a magnetic shield. We’re diving deep into the solar fireworks that are stripping the Martian atmosphere, and what these high-stakes cosmic collisions tell us about the survival of planets.
Jacob, it’s a real privilege to have you here on the show.
Jacob: And thanks so much for having me. I really appreciate the show you have here. And yeah, I’m super excited to show you what I found and also to share the story of how we got it.
Brendan: Awesome. Thank you. That’s great.
Just before we dive into that story and ESA’s high stakes physics, I want to look at your own launch phase. Can you take us back to where you grew up, please? Was there a specific moment or perhaps a particular discovery that first pulled your focus away from Earth and towards the complexities of space?
The Road to ESA: Biology, Space Engineering, and Media Internships
Jacob: Sure. So where I grew up — I actually want to start on a tangent. So I grew up in a tiny county called Rutland. It’s the UK’s smallest county. But for your Astrophiz audience, it’s only the smallest county in the UK for part of the day, because the moon is pulling the tides in and out of the Isle of Man. So Rutland can only be the smallest county in the UK for just part of the day.
But yeah, so I grew up there. If it’s a launch phase, then it suffered a lot of false starts and many setbacks. So when I first got into schooling when I was younger, I wasn’t very good at it. There was extra lessons and learning support for most of the subjects. But we do an exam here, one at about 16, called the GCSEs. And I got surprisingly good results. And that just flipped a switch in my brain. And I thought — oh, maybe I can do this schooling thing.
So I always had a love for biology. So not physics, not space, but it was actually biology most of the time. And my favourite book growing up was this huge photographic encyclopedia of all the animals in the world. I mean, the book wasn’t the size of a data centre, so it wasn’t all the animals in the world, but it was all the pretty ones, all the interesting ones.
I had a love for biology, and in the final year of school, we were given a project of independent study. Go produce a report on something you’re interested in. So I started a project on the feasibility of using fungi to produce oxygen for astronauts. Back then, I think I just discovered mycology in the world of fungi, and I thought, okay, these little guys can do everything. It’s such a strange world. So I did a project on, yeah, oxygen production.
And I had a great supervisor for this private study project. And I have memories of sitting in his office talking about space. It was just open-ended conversations with a teacher. We were speaking about generation ships. We were talking about Drake’s equation, stuff like that.
I kind of always thought I was going to be doing engineering, just the type of brain I had. So yeah, not science, more engineering. And then I saw that you could do a space engineering course at university here in the UK. It’s got a long name. It’s electronic and electrical engineering with space science and technology, but we can just call it space tech. So when I saw that I could do engineering plus space, then I knew that was the main shot.
Brendan: Wow, okay. Now, it’s often said, as you’ve implied, that the path to the stars is really a straight line. And looking back at your school days — A, was the dream always specifically Mars and radio science? And B, did your ambitions shift as you began to master the tools of engineering, electronics, and media production and communication? How did your early goals evolve into the research you’re leading today?
Jacob: So I think starting a space tech course at university always ensured that space remained centre stage. But I also joined a society at university called Campus TV. And this was a kooky, wacky group of people who film things. They go and film university sports events. They get interviews. They do comedy sketches. So it’s not a film appreciation society, but it’s a filmmaking society.
And one of my friends in this group told me that they have a friend’s dad who works at the European Astronaut Centre in Cologne. And they’re looking for media interns. So I had some fun side projects doing media at university, but I also had a space tech degree I was working on. So this sounded like an incredible opportunity. So the media really came to the forefront when I started a media internship at the European Astronaut Centre.
And I’m not sure whether you’ve had another guest from this place, but this is an amazing office. It’s where all the European astronauts actually work. It’s where their nine-to-five is when they’re not in orbit. Wow. So I’ll just be in the kitchenette in the office, and then just Tim Peake, the British astronaut, would just come past and just use the washing machine in front of you. It’s bizarre. But I was a media intern. So that means my job was to script and shoot outreach footage from the astronauts. There was a lot of setting up teleprompters and getting them to read things — you know, Tim Peake doing the 200th anniversary of scouting, that kind of stuff.
And there was also filming actual biological experiments. So all the ISS science is mostly biology because we have humans up in space. So I had to film two scientific experiments that they would then review once they’re on the ISS, on their iPads, such that they could conduct the experiments. One was a muscle biopsy experiment that I had to film. And then one was an interesting experiment where you put on a VR set of goggles and you have to spin around in zero gravity. And we were testing the sense of proprioception. And this is the sixth sense. It’s — how do you know where your hand is when you don’t feel anything? You can’t see anything. You can’t hear anything. How do you know where your limbs are? That’s proprioception. So it was a test into that.
So yeah, it was media, but it was also shooting some science stuff as well. So it was a fantastic internship. But that media experience led into what I’m doing today, not necessarily by the skills it gave me, but more it gave me a complete tunnel vision on — I have to get a job at ESA. That’s it. ESA’s great.
I was an intern, probably 21 at that point, and I knew that ESA had a grad scheme. And I was like, okay, I’m going to get tunnel vision on this grad scheme. I must get this grad scheme. So I had my eyes focused on that for the next two years of my university time. And fortunately, I had a great supervisor for my final year project. This is where you’ve got to make your dissertation at the end of your master’s. You have four months. They tend to give you a project. But my supervisor for that was like, we can do whatever you want. So I put all my eggs in one basket. And I changed my entire final year project to fit just one job application. There were about three jobs I could apply for in the grad scheme at ESA. And I just completely changed my project to fit into this.
So when it came to the interview, I was like, ah, yes, I’ve already been doing this four months. So yeah, it was a big risk. But yeah, I think that’s roughly how I ended up getting there. And the job description was radio science for Martian orbiters. So then I just did that for the final part at university as well.
Brendan: That’s fantastic. I’m sure there’s a lot of listeners now, including me, turning totally green with envy. What a great launch for your career and a wonderful internship. That’s just — oh, that’s beautiful, Jacob. Well, so — that first degree was a Master’s in space science and electronic engineering at the University of Bath. And then after that, you embarked on your doctorate at Imperial College London.
Now, for our green early career researchers and undergrads who are listening right now, could you tell us how you arranged it and why you decided to do your PhD at Imperial College London?
Jacob: Sure. I would love to tell you that I was finishing my grad scheme at ESA and I had a large roster of potential places I could go. You know, I had people knocking on the door asking for me to do a PhD with them. But in reality, if you’re doing radio science for the planets, there’s not many places you can go. So I reached out to some places — maybe four — that would actually fit me, and Imperial was the only one to respond.
So for the early career people, or the people who might be reaching out and trying to find their own self-proposed PhD, it’s a lot of stalking potential supervisors, and the realisation that there’s actually not many institutes that do fit in with the very esoteric niche that you’ve carved out. So it was very lucky that it was Imperial, because Imperial is a good university, but it also has the largest endowment of any UK university. So they had the money to fund a self-proposed topic, because they weren’t advertising this. This wasn’t a normal PhD where there’s a supervisor and funding and a topic, you know, packaged together, and then hundreds of people apply and they fight it out to see who they give it to. This was me coming with my work that I did during my grad scheme at ESA and saying, I’d like to extend this into a more scientific realm. And yeah, they took the bait.
I loved my supervisor at Imperial. He’s an amazing man. And it went really well.
Brendan: Beautiful. So that research trajectory, it’s centred on a very high-level speciality, as you’ve just indicated, and your topic — “Martian aeronomy with mutual radio occultation”.
Now, to help our listeners and myself to get our bearings, could you define the mission for us? And what is the science of aeronomy actually trying to solve? And how are you using radio occultation as a primary tool to unlock the secrets of a red planet?
Hacking Mars Orbiters: The Science of Mutual Radio Occultation
Jacob: Yeah. So aeronomy is the study of the upper atmosphere. So us earthlings on the surface of the planet, we’re so concerned with the troposphere that we inhabit. You know, even our planes are in the troposphere. Even if we’re at the top of Everest, we’re in the troposphere. But aeronomy is just the study of everything above this. And this includes the ionosphere, which is the charged regime above, in the high altitudes of our planet. And I’m doing the Martian aeronomy. So that is the study of the upper atmosphere on Mars.
There is a reason I’m not doing the entire atmosphere of Mars, and I think I might come to that in a later question. It’s a very technical drawback of our experiment, which meant that I couldn’t get the lower atmosphere in my readings. This isn’t really by choice that I’m doing aeronomy. I think I would have liked to do the entire atmosphere, but I’m stuck to the higher altitudes for now until I figure out some processing thing.
Radio occultation. How are we using radio occultation to look at this? So occultation — the English word occultation — is just a very fancy word for blocking. So during an eclipse, the moon is occluding the sun. That’s an occultation. And radio occultation is when there is a transmitter and a receiver sharing a radio link, just like a string between two balls flying around. Their radio link will be occluded. One of the transmitters or receivers will go over the relative horizon. It’ll just get blocked. And just before it dips down over the horizon, this radio link will bend slightly due to the refractivity in the atmosphere or ionosphere.
So say the receiver is here on Earth and there’s something orbiting Saturn millions of miles away. If they’re sharing a radio link as it cuts into denser and denser layers of Saturn’s atmosphere, it will bend more and more and more and more. And you can look at this bend as a Doppler shift at the receiver. So you’re just looking for frequency shifts and then going back and saying, okay, this frequency shift means it’s this dense at Saturn for this height at this location. Got it. So yeah, that’s what radio occultation is.
And what we’re doing — the key selling point is the mutual radio occultation. So ‘mutual’ is doing all the heavy lifting here. For decades we have been doing radio occultation by transmitting from a spacecraft going around a planet and then receiving it at a ground station on Earth. But mutual radio occultation has now brought the receiver to the same planet. So now it’s two spacecraft orbiting, sharing a radio link and doing it that way. And there are a lot of benefits to doing it like this. I guess the easiest one to understand first is: the transmitter and the receiver are closer together, so the signal-to-noise ratio is much better. You don’t have to send a signal through dispersive space that affects the signal. You don’t have to send it to a ground station where the Earth’s atmosphere and ionosphere are probably much, much larger than the thing you’re trying to measure at the other planet.
But the key thing that I like about mutual radio occultation is it lets you see the middle of the day and the middle of the night, which is critical for the key scientific takeaway of the chat we’re having — that we saw the solar storm. Yeah, mutual radio occultation lets you just see any part of the planet. But if we’re doing conventional radio occultation — I’m going to have to ask listeners for a bit of imagination here without a diagram — conventional radio occultation from a spacecraft going back to Earth is geometrically constrained. It’s held back, because if you are crossing the horizon relative to Earth to do a conventional radio occultation, you’re also crossing the horizon relative to the sun — just because for Mars, the Earth is closer to the sun than Mars is. So it means conventional radio occultation just keeps getting measurements near sunset and sunrise all the time. You only see sunset and sunrise. You never see the middle of the day. You never see the middle of the night.
Mutual radio occultation does not have this problem. So that’s really exciting, especially if you’re looking at the ionosphere of Mars, because that’s controlled by how much the sun is knocking electrons off the particles in the atmosphere. It’s completely solar controlled. Yeah, so mutual radio occultation lets us see the middle of the day, middle of the night, which is great for ionospheric measurements.
Brendan: Well, that’s fantastic. And it sounds like you are hacking satellites. Okay. To do this work, you rely on a high-stakes partnership currently circling that red planet. I’d love for you to introduce our listeners to those collaborators of yours — Mars Express and the ExoMars Trace Gas Orbiter. Now, they’ve been up there for years. They’re doing very different work. What are the primary scientific missions of each one, and how do they specifically team up? You’ve told us about the occultations that happen when one goes over the horizon. Tell us more. What are they doing to provide that data? For example, we’re leading in to expose auroras on Mars.
Jacob: Sure. So Mars Express got to Mars in 2003. So it’s been a very long time. And it was ESA’s first venture to the red planet. And it was just carrying a broad range of instruments. It was just trying to see as much as possible. So it had high-resolution cameras, it had a spectrometer, it had a subsurface sounder. It’s called Mars Express because it was developed in a very quick development time. It shared components with Venus Express, and it also got to Mars in an incredibly lucky short period of time. So just the transit was tiny, because of a very rare combination of orbits between Earth and Mars. And this combination won’t happen again for 150 years. So Mars Express was fast in two senses.
Trace Gas Orbiter is much newer. It arrived in 2016 and it’s part of the ExoMars program. So this is ESA’s program to look for signs of life — most likely past life — on Mars. So it’s got more stuff like methane detectors, water mapping instruments. But the ExoMars program also involves the Rosalind Franklin rover, which is still getting tested here on Earth. So that would be ESA’s first rover to the red planet.
And that means that Trace Gas Orbiter also had to be a relay hub. It’s just a very big, powerful antenna. It receives the weaker, fainter signals from the smaller antennas from the rovers. And it then amplifies it and powers it up for its high gain antenna and shoots it back to Earth. So it’s also a key part of the networking infrastructure on Mars. In fact, over 50% of all the data going around on Mars has to pass through TGO — must pass through Trace Gas Orbiter. So it’s critical. And that’s for all the agencies. That’s not just for the ESA stuff.
So both Mars Express and Trace Gas Orbiter went up with landers. So landers are just like rovers, but they don’t have wheels. They just go and they just sit there and they just measure things. And Mars Express went up with the Beagle 2 lander. And Beagle 2 wasn’t successful, because its key antenna to link up to Mars Express was covered by a solar panel, and that solar panel failed to deploy upon landing. So it got cut off from the wider universe because its solar panel was lying on top of its antenna.
Trace Gas Orbiter also had a lander. It was called the Schiaparelli lander. And I actually had to do some signal processing work to investigate why this happened. I’m not saying I found out why it happened — people already knew a long time ago — but I was calibrating my instruments off the failure measurement. So Schiaparelli also didn’t work out, because it had an uncontrolled spin as it descended into the atmosphere. The aerodynamic simulations didn’t show it would be spinning this much. And if you’re spinning in one direction, just centrifugal forces will also point you slightly off the ground — just the physics of spinning. So this meant that the altitude sensor on the bottom of the lander wasn’t pointing directly down. It was pointing slightly off. And you know, Pythagoras — the hypotenuse is longer than the adjacent. So it thought it was much higher than it actually was. So when it got low enough and it had to blast off its retro thrusters and nicely settle down, it did that way too late. So it crashed into the ground.
But this is all good news for me. Definitely not for the hundreds of scientists and engineers beforehand, but both the Beagle 2 lander and Schiaparelli lander had antennas which were designed to communicate with their corresponding orbiter. So Mars Express has the Melacom antenna, which was meant to talk to Beagle 2. And Trace Gas Orbiter has the Electra antenna, which was meant to talk to Schiaparelli. Both these antennas are now just mostly redundant and open for extra purposes. So now I am reusing those antennas to share a radio link between each other, to then do this mutual radio occultation.
Brendan: That is beautiful. Fantastic, Jacob. That’s a brilliant overview of the hardware — having those two satellites and antennas to do what you tell them to do. But here’s the part that really fascinates me. These spacecraft were designed for their specific individual missions, as you’ve described, yet basically you’re retasking them into that high-stakes partnership that tells you so much. Can you walk us through the MacGyver aspect of this science? How do you actually get these two independent orbiters to perform their unintended dance, using their communication links to peel back the layers of the Martian atmosphere and the ionosphere — precisely when the sun is hurling flares and plasma at a planet. What is the secret to turning a communications tool into a deep space sensor?
Inside the Mother’s Day Solar Superstorm
Jacob: Yeah. So a communications tool is actually quite easy to convert into a deep space sensor, just because I am fundamentally just looking at a very, very precise frequency change. So up here on Earth, we have radio systems — which a while ago were either amplitude modulated or frequency modulated — so we’ve had this technology for a long time. And the type of modulation has increased in sophisticatedness by orders of magnitude over the last couple of decades. But fundamentally we know how to look at very precise frequency changes. And if a sensor was designed to look at the frequency changes that encoded information, the physical hardware is also there to look at just the frequency changes which show the change in refractivity of the Martian atmosphere. The hardware is there. Fortunately, we can just upload a firmware upgrade to the spacecraft such that they can interpret the information slightly differently.
As I said, TGO got there in 2016, and its two-year primary mission ended in 2018. So when a primary mission ends, there’s then a call that goes out through ESA saying — what else do we want to do? And mutual radio occultation was always an idea, but it wasn’t part of the primary mission. So then the question was: okay, we want to send and receive a signal at Mars. We have two ESA orbiters for the first time. Do we send from Mars Express or do we receive at Mars Express? Which way are we going to do it?
And ultimately, it became a decision between something called open loop or closed loop. So you can record a signal in closed loop, which is probably what your phone is doing, maybe your laptop is doing it now. Say there’ll be a single carrier tone and there’ll be modulations on top of that carrier tone. And closed loop will use a device called a heterodyne receiver, which will lock onto that frequency. It closes the loop. So you can then measure much more precisely the frequency changes, because you kind of have tunnel vision on a specific frequency. Open loop on the other side is just where you record everything. You record the widest bandwidth possible — you capture as much as possible. So if there are waves on the top of a swimming pool, open loop is just looking at the entire pool. And then closed loop is just looking at a single swimming lane. So it’s easier to understand and you can look closer. So TGO could do open loop, but Mars Express can’t do open loop.
Not only are we tracking the frequency change as the two spacecraft descend over the horizon — so you can see a little bit less of each other and then you can’t see each other, that’s called an ingress occultation — but we also do egress occultations, meaning you can’t see each other and then you can see a bit of each other and now you can. They’re rising over the horizon. That’s an egress occultation. And when the two spacecraft reveal themselves to each other in that way, you have no idea what the frequency is between the two of them. You don’t know what the atmosphere is doing between the two spacecraft. So you have to record open loop just so you can be sure that you’re going to see the frequency. So yeah, you don’t want the tunnel vision for an egress occultation.
So that was the decider. That was — we’re going to send from Mars Express. We’re going to receive at Trace Gas Orbiter. So we only needed to do a firmware upgrade to Mars Express. Because the first four times we did the measurement, when I got the data back, it was filled with silent periods. The signal was horrendous, because Mars Express just didn’t know how to transmit a simple carrier wave. It just didn’t have that ability. So we originally set it to do a hail sequence, which is basically do what its antenna was designed to do — shout out into the abyss for the Beagle 2 lander. It was the hail sequence. And that’s all it knew how to do. So I was looking at the signals from the hail sequence and it was terrible for radio science. So we did have to upload a firmware upgrade to Mars Express to ensure that it did a simple carrier wave.
You asked about how do we get the two orbiters to do this unintended dance. I do the orbit simulations myself with an ephemeris system called SPICE. It’s just a system that says where each spacecraft and planet is going to be for every second of all time. Imagine just the spacecraft is on a roller coaster track. It just says where things are going to be — not calculating the physics, it just says where things are going to be based off someone else’s supercomputer simulations. So I do the orbit simulations with that, and I can see when egress or ingress occultations are going to happen. And then I would take them to the operations centre at ESA — well, I wouldn’t take them, I’d send an email. That’s in Darmstadt. The operations centre — this is kind of like our equivalent of “Houston, we have a problem.” This is where the operations happen. I’ll take the times to them and I’ll give them 100 and they’ll come back with two possible moments.
And so we’re testing a new idea. So it’s the absolute lowest priority. And you know how I said that over 50% of all the data going around Mars goes through Trace Gas Orbiter — it means if we’re anywhere near any of the surface assets, you know, Curiosity or Perseverance, if we’re anywhere near those, you can’t jeopardise that link. You know, if Perseverance just took a new photo, that absolutely has priority on uplink over our radio science sessions. So proximity to surface assets is a huge limiting factor. But then also sometimes the sun is in the way — so there’s a solar conjunction. So the sun is blocking Mars from us. And yeah, sometimes a measurement will happen and then it will just sit on Trace Gas Orbiter’s hard drives for around two months. So there are all these other constraints in making this happen.
Brendan: Beautiful. Absolute satellite hacking at its finest, Jacob. Now, for the engineers and data crunchers in our audience — and for me — I’d love to follow the signal path. How does that raw radio pulse at Mars make its journey across 300 million kilometres of space to land on your workstation at ESA? Could you walk us through the pipeline from Mars to your own laptop? And once you’ve got that data in hand, what does your toolbox look like? What software environments or custom algorithms are you using to strip away the noise, and reveal the exact moment those solar bolts hit the upper Martian atmosphere?
The Data Pipeline: From Mars to Python
Jacob: So I think this question is going to be by far the most technical. So you’re talking to an electronic engineer who has been doing this signal processing for about seven years now on mutual radio occultation. So this has been my life. I live and breathe this processing pipeline.
We’re looking at a tiny frequency shift and this is recorded at Trace Gas Orbiter, and it sits on its hard drive until there’s a good moment where there’s not other higher priority information or the sun isn’t in the way. This comes down through the deep space network, through either the 30-metre dishes or the 60-metre dishes. There are American, European, but also we use Russian ones. So that’s one of the few things that’s been severed since the Ukraine invasion — we are still using Russian ground stations, because they’re massive. They’re like 65-metre huge antennas. So they have incredible link capacity.
So then that’s now back on Earth, and it comes through a secure system which I then download it from. So it’s now on my computer. It’s in a format called in-phase and quadrature — it’s basically just the way to record a raw waveform. I will then try and extract the carrier frequency from this with a fast Fourier transform, then another thing to increase the frequency precision even further, some fitting processes. And this is where you’ll just see the frequency shift that you see during the measurement.
We always take 10-minute measurements and you’ll see a nice parabolic change in frequency during the observation. This is completely dominated by the Doppler shift — the Doppler shift that you and I see here on Earth, the reason the train sounds different when it’s going away, or the way that police speed cameras work. The Doppler shift is dominating this. The motion of the two spacecraft produces kilohertz of frequency shift, and I need to get less than a hertz of frequency shift due to the atmosphere and ionosphere of Mars. So I simulate the orbits. I subtract this Doppler shift from the two-motion of the spacecraft. It looks kind of flat — but it’s not really.
And this is where the critical issue of this entire system lies, and where we really see that these two spacecraft were not designed to do mutual radio occultation. All of this hacking cannot overcome this one problem. And it’s the issue of local oscillator stability. So we’re looking for a tiny frequency shift, but to record a frequency shift, you need a really precise clock on your spacecraft. And if you’re doing conventional occultation where you’re receiving a spacecraft back on Earth, you can have a huge ultra-stable oscillator — sometimes called a hydrogen maser — which is basically like an atomic clock and that is very, very stable. It can look at frequency changes really well. But up in space, you don’t have the energy, you don’t have the space, you don’t have the size, the capacity inside the spacecraft. So we have quite an unstable oscillator at the receiving spacecraft at Trace Gas Orbiter. So I have to do a lot of modelling, a lot of other fitting to get rid of this drift. And I have to make some assumptions in this way. And these assumptions are why I’ve always been talking about aeronomy. This unstable drift is the reason I cannot see the lower atmosphere. And I never will. We will just need new hardware to see the lower atmosphere. So that is the drawback, and that’s why we’re only ever talking about the upper atmosphere here.
Yeah, you’re asking about the tools. The tools is Python. All my processing is in Python.
Brendan: And I bet a lot of our early career astronomers just went — yay, Python!
Jacob: Yeah, exactly.
Brendan: Yeah, yeah. Okay. This is where it all comes together. You and the team you’ve been working with have just published a powerhouse paper in Nature Communications titled Martian Ionospheric Response During the May 2024 Solar Superstorm, also known as the Mother’s Day Superstorm. I was thrilled to see it was open access. And so, look, I’ve got to admit something here. I really only understand the abstract and the conclusion. Everything else goes way over my head, but I think I’ll be able to go back and understand a bit more now, thanks to the explanation you’ve just given us.
Now to the big reveal. When that solar superstorm actually slammed into Mars, what did your data show? What was the physical reaction of the Martian ionosphere? And once the results were out — this is the third question, I’m sorry about that — what was the ripple effect among your peers in the planetary science community?
Jacob: The data showed a huge response in the ionosphere. So the main way scientists measure the ionosphere is electron density — how many free electrons are flying around per unit volume. So electron density is the main word. And our mutual radio occultation observations — the final output of all of that — is an electron density profile. So just imagine a long tall graph where you can see the electron density with respect to height.
And we saw the normal ionosphere on Mars, which consists of an upper M2 layer and a lower M1 layer. We saw that the upper one, the M2 layer, was a little bit bigger. But then we saw that the lower M1 layer was massive. It was three times bigger. And this actually is the largest response to the sun we’ve ever recorded at Mars. And this bump was especially interesting.
So what is the physics going on here? Some of you listeners may be aware of the Earth’s ionospheric layers — the E layers and the F layers. And they’re produced by different frequencies coming from the sun, different energies of photons. So the upper layer is caused by extreme ultraviolet. So imagine the ultraviolet that we have here down on the surface of Earth, but the wavelength is a little bit shorter — it’s higher frequency. And then the lower layer, the really interesting one, is caused by soft X-rays. So the X-rays in our X-ray machines, but now the wavelength is a little bit longer. It’s softer. It’s a lower frequency.
And the conventional wisdom — all previous reports on this dynamic had said that the density of these layers are proportional to the square of the irradiance. So if I throw two times more photons down at the ionosphere, then the ionosphere will grow by four times. That was the conventional wisdom.
But because we’re doing mutual radio occultation, which has this extremely rare superpower of being able to see the middle of the day — for the first time, we’ve seen a middle-of-the-day measurement during a solar storm. So that’s getting the full whack of all the photons just straight down onto Mars. And even though our measurement showed the lower layer increased by three times, I took a measurement from an in-situ sensor. So there was a sensor on the MAVEN spacecraft orbiting Mars — so not a simulation — we just looked at the measurement from another spacecraft at Mars, and it showed that the irradiance had also increased by three times. So now we have this bizarre linear relationship of amount of photons going up three times, and now the electron density going up three times, which we really hadn’t predicted before.
And perhaps that sounds like a boring result to most people — like, okay, it’s not squared, it’s actually just one goes up, the other goes up by the same amount. But this means that each photon is producing much more free electrons than we had originally thought. So the key idea from the paper is: a high energy photon comes in, it produces a photoelectron by photo-ionisation. But then, because that original photon was so high power, that electron that’s come flying off just now goes off and produces secondary ionisations. It produces a cascade effect. It knocks off a lot more electrons — like a billiard table. And yeah, that was the key takeaway. We are under-predicting the contribution of photons. A lot more electrons come from this.
Yeah. So you’re asking about the ripple effect in the community. I submitted this paper almost two years ago, and it just took a very long time to get through review through Nature Communications. So it only came out last month. And you know how the publishing process takes. I’m not sure who’s cited it. I don’t really know what else is going to happen from this point. All I can see right now is this thing called Altmetrics, which is a system which shows general engagement on your paper — press engagement, people’s downloads, where those downloads are happening. And I can see it’s in the top 1% of the papers for last month. But I don’t know how this will affect the wider scientific community, just because of the timescales of science. I’m not sure where this will go. It’s very exciting, though.
Brendan: It came and slapped me in the face, I tell you. Okay, that leads us perfectly into the reality of the scientific process, Jacob. It’s really a smooth sail. You’ve told us all about the tweaks you’ve had to do all along the way through this process when you’re working across international borders on such a specialised frontier at ESA Radio Science. I’d love to get a look at the bleeding edge of your current work. Is there a specific puzzle that you’re untangling right now that’s driving you absolutely crazy? Or perhaps a recent data set that is so astonishingly exciting that it’s keeping you up at night? Is it often the case in planetary science — is it a bit of both?
Jacob: Yeah. The magnetic field. The magnetic field of Mars is a bizarre, strange creature. So as I said a little bit earlier, mutual radio occultation lets us see the middle of the night. And the ionosphere on the night side — once all the photo-ionisation from the sun has dissipated — the ionosphere is controlled and it’s modulated by the Martian magnetic field. So it can cluster up, it can stream out. So if you looked at the night side and, say, you put on some glasses that could only see the ionosphere, it’d look a bit like a Dalmatian. There’d just be dots of ionosphere all over it. So it’s a very bizarre system.
And Mars has this because it used to have a magnetic field — a bit like Earth — caused by an internal dynamo of magma rising and falling and causing a spinning movement. Mars used to have something like that. But just because Mars is smaller than Earth, its fissile material — the material that actually generates the heat inside the core of Mars — has cooled off quicker. So Mars used to have a magnetic field, but now it doesn’t. But that left magnetic domains in its crust. So you end up having a very bizarre patchwork of magnetic field.
And what’s keeping me up at night is: can I see those patches with our mutual radio occultation data? Can I leverage the fact that we can see the middle of the night to see these middle-of-the-night modulated ionospheric patterns? And yeah, we’re still making up our minds about how Mars has this strange intrinsic magnetic field, because you would like to say that it’s cooled off and the core is solidified — therefore you don’t have this huge magnetic field. But we’re actually seeing results that suggest there is actually a liquid core here.
Because you can look very, very precisely at how Mars is spinning — a bit like the spinning tops that you see at the end of Inception. You can see that the central axis is rotating in such a way as Mars is spinning around the central axis. You can see that this tiny motion — called nutation — is actually saying that Mars has a liquid core. And they did a really interesting experiment. They used a diamond anvil — so they put two big diamonds together and they shot a laser at it, and they squeezed some magma together. And they used a magma which was a great simulant for the core of Mars. And it showed that if you heat it up with a laser and compress it to Mars core pressures, the magma is liquid, but it becomes immiscible. And immiscible is like olive oil over water — it just separates out like this. So it’s really interesting — is Mars just a liquid core, but they’re separated out because they’re immiscible?
So I think the Martian magnetic field is what is keeping me up at night, and I really want to see it with my data.
Brendan: Fantastic. And it’s great to see into the background and the work of a researcher. But let’s look into your role at ESA as a radio scientist. When you’re not untangling that data from a solar superstorm, being puzzled by magnetic fields — what other gears are you turning at the Space Research and Technology Centre? How do your responsibilities shift when you move from scientist to ESA agency officer? Are there non-research tasks that you have to perform to help ensure that ESA stays at a leading edge of planetary exploration?
Jacob: There absolutely is. It’s just — this is the part of the interview where my lips are getting zipped.
I spend most of my time doing this other work. You know, ESA is obviously working on future missions for Mars. It’s just very much above my pay grade to say what these things are. I can say I am releasing all of this mutual radio occultation data out into the wider public via the official ESA archives. And yeah, I mean, archiving probably sounds boring, but there’s one thing of generating the data for myself to work on, and then there’s another whole beast — generating the data that is uniform, standardised, that the rest of the world can just take and plug into their science. Getting my data to planetary science archive readiness levels is also a lot of work. Possibly boring, but yeah, archiving is also taking up maybe 20% of my time, and then over 50% of the time is the secret work. And then I’ve got these interesting research fields that are quite small right now, but it ebbs and flows throughout the year.
Brendan: I can predict that I’m going to be asking you for another interview in about 12 months’ time to hear about this secret. Anyway, we’re seeing a paradigm shift across the entire scientific landscape with the integration of AI, artificial intelligence. Is AI becoming an essential co-pilot — I shouldn’t have used that term — is AI becoming essential for the radio scientist, helping us to find that signal in the noise of the Martian ionosphere? And where do you see this partnership between human intuition and machine learning? Where’s that partnership heading? And are you seeing it move just beyond automation into — I don’t know — the realm of discovery, perhaps in how we sift through those petabytes of data from the Mars orbiters? Predicting atmospheric signatures of the next solar superstorm? How do you see it from your vantage point at ESA?
Jacob: It’s affecting ESA as it is the rest of the STEM community worldwide. It is a formidable force. I have some examples where it even reveals some creativity.
When I was finishing my PhD at Imperial last year, and I had written my thesis — it’s a 200-page dense document, you saw it — and I was preparing for my Viva, which is the interview at the end of your PhD. It’s often a six-hour grilling with two professors. And I wanted to prep for it. So I gave — I think it was GPT back then — and I just plugged it in. I said, find me some difficult questions from this. And it thought for 10 seconds and then spat out the most targeted, brutal questions. The things that I tried to write around, I made some assumptions, things I tried to push some dirt over and forget about — it found those immediately and grilled me on them. I was amazed.
It can definitely go far beyond just grunt work and sifting through the petabytes. We’re not calling it AI, but machine learning — there is a machine learning group within ESA, and I often attend their lectures. And it’s very interesting. Planetary science produces some data, but then when we go to astronomical science, then now you’re sifting through the petabytes, and they absolutely do deploy AI for this. And there are so many fascinating things that they are doing with that.
I think the AI usage, it is the future. I don’t think we’re going to decide, oh, we need to step back a bit. I think I’m not really sure where to stand on the current optics of AI. I think the global conversation right now is dominated by non-technical people who can only contribute a doom-and-gloom narrative. You know, if something is big and is at the forefront of humanity, I think there will always be stories about it being secretly evil or a lot worse than we actually think.
I do get behind it. And I am actually building my own machine learning technique right now. There’s a fundamental assumption that we’re making with every mutual radio occultation measurement — actually, with all the radio occultations, even the ones we do on Earth and other planets. There’s an assumption that we make that actually reduces the precision of our measurements. And I’m developing a machine learning technique to get around that and to increase the resolution. I’m not asking a machine learning tool to be creative, but I am asking it to run thousands of simulations such that I can then reverse physics. So a lot of great uses. And I’m also using it myself. And I think it is here to stay.
Brendan: Thanks, Jacob. AI is here to stay and it’s fun watching it evolve. And it’s one thing to have all the pipelines and all the data sets and AI in your back pocket. It’s another thing entirely to have the clarity to interpret it. You’re solving some of the most puzzling phenomena in planetary science. Now, that requires an immense amount of focus. Sometimes I lack a lot of it. I’m curious about your process, though. Where does some magic happen for you? Is it in the quiet of a high-tech lab at ESA or somewhere completely unexpected? What are the conditions that you have to create to filter out the noise and find the signal in your own thoughts, Jacob?
Jacob: Well, I am still relatively junior at ESA. So there is no way I’m getting my own office. So background noise is completely normal. And noise-cancelling headphones are a thing of magic. So, you know, dopamine is not just the neurotransmitter for happiness. It’s also for motivation. I like to keep the dopamine high whilst listening to music. Obviously, no words in English. And if I’m not into any band at the time, I can always switch back to the old trusty of video game music. And because I’m speaking to an Australian right now, I think I should specifically call out Adelaide’s Team Cherry, because they make two games called Hollow Knight and Silksong, and they have incredible soundtracks.
Brendan: Yes. Okay. Well, I can understand how they’re a great inspiration for you. Now, you’ve given us an incredible look at the big picture of the Martian ionosphere and how it responds to those vicious attacks by the sun. And I’m struck by the diversity of your own background — from your days as a video creator to your time as a student volunteer on the helplines at Bath. Now, beyond the data and the deep space infrastructure, what is fuelling your curiosity? What are the passions or pursuits outside the laboratory that bring you the most joy and help you — this is all about you, the person — maintain that essential balance while you’re exploring our solar neighbourhood?
Jacob: I think health is pretty critical for balance. So I’ve been doing the normal gym stuff for a while, but now my girlfriend and I have switched to something called Hyrox. It’s basically CrossFit. Just imagine CrossFit. But when you enter a competition, you can do it with someone. So you share the load, you share the reps. So it’s just a fun thing I can do with my girlfriend. It’s exhausting, but it is rewarding. And it definitely helps keep my health ticking along.
Apart from health stuff, I write for a kids’ magazine called Aquila. So some of my recent articles would be, you know, do aliens exist, should we be taking dogs into space — I like that article because I go into the actual practicalities of taking a dog, and could we use their excrement for farming, could we use excrement for building bases — just fun stuff like that. And I always love to see what the illustrators do with my words.
You know, I am an electronic engineer so I am a nerd at heart. And last weekend I ripped apart my old gaming PC and I converted it into an extremely dumb local AI. I’ve named it Tugboat, and it’s currently tasked on finding my girlfriend a job. She has a job right now, but it’s just hunting — it’s just hunting for her. So it is not smart enough to write an application, but it is smart enough to click around on the internet and then find what is suitable according to her CV. So it’s not smart, but Tugboat is a simple man — but he has tenacity. He is always on. He is always clicking around. So that’s a fun side project as well.
Brendan: That’s outstanding. And look, I really hope Tugboat finds a really fabulous job for your girlfriend, Jacob. That’s awesome. Okay, look, we’ve covered the hardware, the hacking, the high-stakes physics of the Mother’s Day storm. But science, as you’ve just told us, it’s essentially a human endeavour. And to wrap up — you know, for me it’s heading towards mealtime, for you you’re heading off to work. I’m handing you the golden mic. What is the one thing in the world of science or society that you are most passionate about right now? Whether you want to champion equity and representation or call out the barriers to discovery, we want to hear your unfiltered perspective. What’s your final word for the Astrophiz audience, Jacob?
Jacob: I think I’m going to be preaching to the choir here. And I’ve noticed recently — I don’t know, in the last five years — that certainly in Europe, people my age have become very pessimistic about the future, and they have negative impressions on technology and especially space. I always hear at any party, there’s always — why are we sending stuff up there when we could be spending money down here and fixing things like climate change.
And I just want to say that I don’t think this counterfactual is as clever as you think. And it’s very short-sighted. So first of all, why are we spending money? Well, economically, I can only provide stats for the UK, but every one pound spent on the space industry returns seven pounds back. So you’re not throwing money away at all. And then our modern world is filled with surplus technologies from the space industry. You know, the reason your glasses scratch less, the reason your phone knows where you are, the sensor just in your phone camera, and even cordless power tools — it’s all surplus from the space industry. And then, of course, the main one is: how many modern high-tech STEM workforce workers got into this by being inspired at an early age by something spacey? You know, how many kids’ lives were changed a couple of weeks ago when the Artemis II photos were shared? I certainly felt like an inspired kid when I saw the lunar eclipse from the outside of the Orion capsule.
So it’s — I know it sounds corny, but exploration is our nature. It might not be in the negative naysayers’ personality, but it is inside the average human. And I think space is a fantastic direction to point our curiosity at. And curiosity is essential. And that’s why we need that blue sky research to drive and respond to that curiosity.
Brendan: That’s beautiful. Okay, Jacob, this has been a masterclass in satellite hacking and the high-stakes physics of a red planet. As we look to the next few years — I know there’s secret stuff you can’t mention — but perhaps the next solar maximum or even the next generation of ESA missions. What’s on your personal radar? Is there a particular mission or specific astronomical event, or even a shift in how we explore the solar system, that you think we should all be watching out for in the near future?
Jacob: Bit of a curveball, but — the Moon. I am turning my sights to the Moon. And yeah, I’ve been on Mars for the last seven years, but the recent announcements for complete, full-on dedication, full conviction on the permanent lunar presence — the lunar base — it has shifted the direction of the world’s space industries. Yeah, it’s led by NASA, but our directorate within ESA — the Human Resource and Exploration Directorate — we’ve also just shifted our eyes to the Moon.
So in terms of my career, I’m following that. I’m following where the interest is. I’m following where the potential jobs would be. And specifically, ESA is going to be making the networking infrastructure for this lunar presence. So if you’re sending a lander or a rover, or you’re going to put a nice little human habitat dome under the lunar regolith, you don’t want to have to carry a huge, high-gain antenna with you. You don’t want to have to send every bit of information back down to Earth. You want to carry a nice little light antenna that then uplinks to a closer orbiting spacecraft, and then that can shoot it down back to Earth.
So ESA is committed to the Moonlight Constellation, and this is going to be the internet and the navigation — the Galileo or the GPS — for all lunar assets. So if there’s a constellation of radio antennas at the Moon, then there are two antennas which can do mutual radio occultation. And even though the Moon’s atmosphere is very boring — i.e. it’s a very loose, gravitationally-bound exosphere — I haven’t mentioned this in this whole talk, but mutual radio occultation doesn’t just see the line-of-sight radio link between the two antennas. It also sees the reflection from the ground. So you can get ground measurements. So I am actively pursuing the feasibility of ground measurements with our occultation setup. So that’s what I’m looking at. Hopefully not right now, but I will be pursuing it during my time at ESA.
Brendan: Beautiful. As one door opens, another five doors open. Thank you, Dr Jacob Parrott. On behalf of all of our listeners across the globe, it’s been an absolute thrill to trace this journey from the radio labs of Bath to the ionosphere of Mars. Your work reminds us that the best science often comes from looking at the tools we have in entirely new ways. I’ve truly enjoyed this conversation. Your generosity knows no bounds. Good luck with that next phase of your current research. The way your career looks, it’s just going to keep on relaunching itself. Your upcoming travels, every frontier you’re yet to cross. May your career continue to be a blast, Jacob. Thank you so much for joining us on Astrophiz.
Jacob: Thank you again for having me. It really has been such a joy chatting to you. And your considered questions were amazing. So I love how you managed to string together a narrative from all the information you found about me. And it has been a pleasure.
Brendan: Excellent. Thank you,
Jacob: Thank you.
Brendan: And from me, good night. And from you, good morning. Thanks,
Jacob: Bye-bye.
Outro: Morse Code snippet
Brendan: Thanks for listening. And remember, Astrophiz is free, no ads, and unsponsored. For transcripts and full show notes, visit astrophiz.com. Find us on SoundCloud, Apple Podcasts or your favourite platform. Don’t forget to join us on the first of each month for Dr. Ian Musgrave’s Sky Guide, and the 15th for our next interview.
Clear skies. Keep looking up!