Today, Anton Ermakov was part of a team that announced exciting discoveries from NASA’s Juno mission at the American Geophysical Union (AGU) Annual Meeting. These results, also published today in Nature, revolve around the Jovian satellite Io and inform our understanding of Jupiter’s other moons, planetary evolution in general, and studies of the potential habitability of satellite systems. 

While a noteworthy moment for planetary science and Ermakov, this isn’t his first involvement in a NASA mission, and his investigations of what exists beyond Earth date back as far as he can recall.

“I’ve loved space since before I remember myself,” said Ermakov. 

For more about Ermakov and his work, here’s the who, what, how, and why of Assistant Professor Anton Ermakov: 

Who are you? 

I’m a planetary scientist who uses geophysical techniques to study planetary interiors. So, I’m kind of a weird guy here because I’m a person with a science background in an engineering department. But hey, maybe it’s not super weird: for space missions, we need to combine science and engineering to build a complex spacecraft with a bunch of instruments that gather science data – which we then use to study the formation and evolution of the solar system. 

What do you research? 

Most of the research I do is related to the analysis of data we get from planetary space missions, which is accompanied by geophysical modeling of planet interiors. Right now, I’m a participating scientist in the Juno mission, which takes most of my time. It’s orbiting Jupiter right now, bringing in data with every new orbit. And when you get new data, that’s when you make discoveries. Juno is a Jupiter mission, but we are in the extended phase. So, we get to use all the Juno instruments to do things they were not really designed to do, like studying satellites of Jupiter. In this extended mission, Juno has been doing flyby surveys of the Galilean moons. We had one flyby of Ganymede, one flyby of Europa, and two flybys of Io. 

We’ve just presented new results from this work at AGU that are about Io, which is the most volcanically active body in the solar system and the innermost large moon of Jupiter. We know that tidal heating (stretching and squeezing of Io by Jupiter’s gravity) is the cause of Io’s extensive volcanism. And the hypothesis has been that Io could have a liquid global layer of magma below its surface, aka, a magma ocean. We care about magma oceans because the presence or absence of a magma ocean controls the eventual planetary interior structure and atmosphere. On top of that, the Io results help us characterize the “dynamic habituality” – how the habitability of planetary bodies evolves over time – of the Jovian system, and most importantly Europa, which is considered one of the likeliest candidates for harboring extraterrestrial life in its subsurface water ocean. 

I led geophysical analysis of the data Juno collected during its two flybys of Io and the new data shows it does not have a magma ocean, at least a shallow one, that can be a source of Io’s volcanoes. Juno’s data support the notion that Io is in the “heat pipe” regime, where volcanic melt can be delivered to the surface so efficiently that it prevents the formation of a magma ocean. 

This measurement of Io’s tidal deformation was one of the main science goals of Juno’s extended mission. Juno is also the last opportunity to get data at the Jovian moon before NASA’s Europa Clipper – which just launched – and European Space Agency’s JUICE mission will get to Europa and Ganymede, respectively. They both have very different sets of instruments, which are very complementary to the data collected by Juno.

How did you end up where you are in your career? 

My interest when I was a kid was observational astronomy. My mother bought me a telescope and I started observing the sky. I was in Moscow observing from the balcony and Moscow has terribly bright sky. So, you could pretty much only see the planets, maybe that’s why I became a planetary scientist. I was also always interested in astrophotography – which is collecting data. In undergrad, I had this super rare major in Russia called space geodesy. It involves building coordinating systems, measuring gravity fields, studying the rotation of other planets – and doing all of this from space. Then, I went to get my PhD in planetary sciences at MIT.

I learned how to do precision space measurements in my undergrad, and during my PhD I learned how to use measurements to study planetary bodies, processes that operate during planet formation and evolution. I started with astronomy, and for astronomy, everything is a dot of light; it’s unresolved, and sometimes you get colors and spectra. When you send a spacecraft, that dot becomes the subject of geology. When you have enough resolution and measurement accuracy to study subsurface processes down to the deep interior and gather hints about planetary evolution, that used-to-be-dot becomes the subject of geophysics. 

During my PhD, I worked with the Dawn mission, which was the first spacecraft to orbit two bodies in the solar system: Vesta and Ceres. So, in the first months of my grad school, I was receiving emails that had images of asteroid Vesta. They were sent by the navigation team to the entire science team, and I received this 40-pixel resolved image of the asteroid and I just thought, “100 people in the world – and me – have seen this picture and it’s not a dot; it’s a lumpy spinning rock with a bunch of craters, grooves, cliffs, landslides and all other sorts of geology happening on a new world we are about to explore.” 

Why are you passionate about your work? 

My answer to this is my personal curiosity. There is a great satisfaction in getting to somewhere that was completely unknown before and discovering a new world where the same laws of physics managed to create something that never occurs on Earth, like Pluto’s nitrogen glaciers or Ganymede’s layers of exotic high-pressure ice phases. But, still, we find terrestrial analogies, do lab experiments, and computer modeling to make sense of what we’re seeing in space data. 

For example, the Juno spacecraft is five astronomical units away from us (roughly 465 million miles or 750 million kilometers) and we know the velocity of the spacecraft down to something like 0.05 millimeters per second. Isn’t this crazy? When in the world do you need to know how fast you are moving to this accuracy? But by studying the spacecraft’s motion and the forces that govern it – such as planetary gravity fields – we can understand what’s inside the object it’s flying by. Gravity fields are sensitive to internal mass distribution, so they can help you determine if there is high-density core, like we have at the center of the Earth, or if there are liquid layers or even oceans inside planets and satellites.

Alongside the discovery of Io’s lack of a magma ocean, there were other surprising results from Juno about Jupiter’s structure. Not only have we found that Jupiter’s core is fuzzy – it gradually merges with Jupiter's atmospheric envelope – but the main instrument in Juno, called a microwave radiometer, has shown that Jupiter’s atmosphere is not well mixed. This is important because, if you want to study Jupiter’s atmospheric composition, this means you can’t sample one spot and assume it’s representative of the entire planet’s composition. 

These are the kinds of discoveries that motivate my work – which means using very, very precise measurements from space missions to start building very, very detailed models to study how different physical processes shape planetary surfaces and interiors.