Julie Castillo-Rogez

Planetary Geophysicist - NASA's Jet Propulsion Laboratory (JPL)


University of Nantes, France

B.S. Geology

University of Rennes, France

M.S. Geophysics

University of Rennes, France

Ph.D. Planetary Geophysics

Julie Castillo-Rogez is a planetary scientist at NASA's Jet Propulsion Laboratory (JPL) specializing in water-rich objects. She is currently focused on dwarf planet Ceres, the exploration of small bodies with small spacecraft, and the formulation of reactive missions to long-period comets.

Where are you from?

I am from Nantes, France.

What first sparked your interest in space and science?

My first personal connection with space occurred during the arrival of Voyager 2 to the planetary system of Neptune. I was also excited when Voyager encountered Saturn, but the Neptune encounter is something I very much remember because I was 14 at the time. This encounter was timely for me because it determined my choice to study more science during high school. I still feel that both the Voyager missions have been very special missions: Their observations gave rise to many questions, which have in part driven the past twenty years of space exploration.

How did you end up working in the space program?

I never thought that I would actually be doing planetary research: I graduated with a degree in geology and did a Ph.D. in terrestrial seismology at Nantes University. This was at the time when a new planetary science laboratory was implemented at Nantes University. Looking back, it was a particularly good thing to have benefited from a background in geology before becoming involved in planetary studies.

Then I met a Cassini scientist in 2000 who hired me right after I graduated to do science planning engineering for the Cassini mission. I also got to brainstorm a little bit about the Jupiter Icy Moons Orbiter (JIMO) mission, the Titan and Saturn System mission, and some Enceladus orbiter concepts.

Who inspired you?

I have met a lot of very inspiring people. In terms of role models, Bonnie Buratti and Linda Spilker immediately come to mind. Dennis Matson has been a great mentor. He should write a book on mentoring, seriously.

Torrence Johnson inspired my research. I remember a presentation he made a long time ago where he mentioned that one should not forget the small bodies (the "potatoes") as an important research focus. I was hooked!

I have been lucky to work with the most competent team during the development of the Jet Propulsion Laboratory's (JPL) Ice Physics Lab.

What is a Planetary Geophysicist?

Planetary geophysics covers a lot of sub-disciplines. Most of my work is about modeling the internal evolution of the so-called "small bodies" or "primitive bodies." Well, most of those bodies are neither small nor primitive! It is very exciting to extract the information these objects reveal about the early history of the solar system and the origin of water in the inner solar system. There are many small bodies – many data points. Each contributes a different piece of the puzzle, and I am having fun trying to put these pieces together.

For this, I use different techniques. First, I try to couple various processes or properties, for example, to see how the chemistry of an object affects its physical evolution, and vice-versa. In order to do that, I work with a lot of collaborators who bring their unique expertise to this interdisciplinary research. Another part of my research is about measuring in the laboratory some input parameters that I can use in models, in order to shed light on processes that are poorly understood right now.

A large part of all research is also about communicating the results to a broad audience –colleagues, sponsors, and to all ages of the public.

Tell us about a favorite moment so far in your career.

I have had the chance to work in missions, which is obviously a privilege, but I must say the most exciting moment was when my colleagues in the Ice Physics Lab and I realized that our project was going to perform far beyond our expectations. We tried to push the limits of the setup until we realized that we could simulate conditions similar to those expected on Europa! At that point, we were absolutely ecstatic, because how often do lab experiments end up working better than expected? Still, we knew that the system would need some updates in order to yield research-grade results. 18 months after starting that project, we decided to pull it entirely apart and start another 18 months of development. (When I present about this facility, I use a picture of my kid as a reference: when we started, my kid was just born, when we finished he was three years old.) Those three years were probably the most exciting three years of my entire life!

What advice would you give to someone who wants to take the same career path as you?

A problem I have had is that it took me a very long time to find out on which topic I would focus my career. I have worked on Europa, Titan, asteroids, laboratory work, mission design, Mars, astrobiology, and material physics. However, I would not claim that I am an astrobiologist or a mission designer, or that I qualify to be part of a mission to Mars. That is the problem of being interested in many topics and getting the opportunity to work on all of them! I am not saying that it is necessarily a bad thing to have broad-based expertise, but it clearly took me a while to obtain enough results in a particular area for that research to become marketable, i.e., to obtain funding in order to be able to carry out that research to the next level.

What do you do for fun?

I am a soccer mom!

If you were talking to a student interested in science and math or engineering, what advice would you give them?

For those students who are interested in planetary science, I would recommend that besides math and physics they should also get a solid background in natural science, including hands-on geology. Simply put, in order to be able to have an understanding of other planetary bodies, one should first be able to understand what the Earth is made of, where it comes from and how it evolved to its current state.

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Where are they from?

Planetary science is a global profession.