Karl Mitchell
Karl Mitchell


Dame Alice Owen’s School
Leicester University
B.Sc. (hons.) in Physics with Space Science and Technology
University of London
M.Sc./D.I.C. in Remote Sensing (Land Applications option)
Lancaster University
Ph.D. in Environmental Science

What first sparked your interest in space and science?

I've been interested in space and science for as long as I can remember. There were a couple of big moments in my childhood that inspired me more to go toward space as a career. One was going out into the backyard with my dad to see Halley's comet, in the mid-’80s. We went outside at night with a camera lens, and he found a way to project Halley's comet onto a piece of paper and magnify it slightly. That started a fascination both with what's out there, and also how to look at it simultaneously. In many ways that led to my fascination with planetary science, not just the theory, but also how to make the observations. That was the first big incident.

The second one? I was always fascinated with the NASA flybys of planets. For me, a particularly big one was the Neptune encounter back in 1989 of Voyager 2 when it was leaving the solar system. We got to Neptune and suddenly we had this moon, Triton, that was spewing out fluids into space. That made me fascinated with that world as a target – it showed me that even though something was far away from the Sun, a lot could be happening. It really captured my imagination in terms of my interest in geological fluids, which I didn't get an opportunity to really study until I did my Ph.D. work. But it made me think a lot about volcanoes and things like that.

Voyager made me aware that there were people who did planetary science. Until that time, I was fixated on astronomy because I thought that was what space was about. It made me aware that there was perhaps more to it than that, and there were other parts. I still started down the astronomy route, but I quickly realized during my undergraduate studies that my interests were more in planets. So I took every opportunity I could to study Earth and other planets when I was choosing my options during my degree. That was largely inspired by both Halley's comet and the Voyager program.

How did you end up working in the space program?

I was a planetary scientist in the UK. I did get a bit involved with an ESA mission, Mars Express. At the time, I was still pursuing the idea of being a lecturer at a British university which might have been space-program adjacent, but certainly wasn't the same as working for a NASA center. But funding being the way that it is, I was going through a period where I wasn't exactly sure what my future was going to bring. The lectureship wasn't coming to me.

I reached out to a colleague, Rosaly Lopes, at NASA’s Jet Propulsion Laboratory (JPL) because we had chatted in coffee rooms at conferences and shared a love for the same sort of things – volcanoes, missions, etc. So I reached out to her and said, "Hey, Rosaly, are there any opportunities? I'm starting to think that spending some time in the NASA system would be good for me, and I think this would be an amazing opportunity. Is there anything you can do?" And Rosaly said, "Well, I'm involved in this mission, Cassini. It's about to reach the Saturn system. Your background is in volcanoes, and we think there might be cryovolcanoes on Titan. Very little has been written about it. We're going to get some data. Would you like to study them?"

I said, "Well, yeah!"

Titan shrouded in haze
Titan is shrouded in thick atmospheric haze in this image taken by Cassini on May 23, 2004, from a distance of (13.4 million miles) 21.6 million kilometers. Credit: NASA/JPL/Space Science Institute

This was going to be the first time seeing the surface of an alien world which was a massive opportunity, so I dropped my Mars studies so that I could focus totally on Titan for a couple of years. To me, in many ways, Titan was pushing further toward that deep space exploration I was really interested in, as well. So it was a fantastic opportunity.

I was on the Cassini RADAR team, and every time we got new data, we all gathered in a room at JPL. The images were long noodle-like swaths, so every time we got new data, we would pan across a brand new image projected onto a large wall at JPL. They were all incredible first-time glimpses of an alien world. The most memorable was one that occurred fairly early in the mission. We'd been predicting there might be seas of methane or ethane on Titan for some time, but that was the first time we saw any hints of it. We saw these dark, nearly-circular features, and suddenly it was like, "Oh, wow. Could this be it? Could this finally be those liquids on the surface you're seeing?" And yeah, over the next few flybys, we saw this incredible wealth of brand new data showing the first evidence of active hydrological processes – albeit with methane and ethane as the fluids – on an alien world.

To me as someone who loved geological fluids, wow, it was huge! So much so that I mostly stopped studying mostly volcanoes on Titan and started studying lakes and seas. So yeah, that was pretty fantastic.

Tell us about your job. What do you do?

Since 2017, I've been working on a mission concept called Trident that would be the first dedicated mission to Neptune's largest moon, Triton. It's a potential ocean world that’s farther from the Sun than most other large, icy worlds in the solar system, except for Pluto and a few others in the Kuiper belt.

Triton closeup
A global color mosaic of Triton, created with images taken in 1989 by NASA’s Voyager 2 spacecraft during its flyby of the Neptune system. Credit: NASA/JPL/USGS

I was involved in this mission concept from day one. In 2017, I was invited to a JPL study session (called the "A Team") where they asked a simple question: If they allowed radioisotope thermoelectric generators in NASA’s Discovery Program, what would it enable? What brand new exciting science could we do? So, I suggested a Triton mission at that meeting. Lots of people liked the idea. I followed up with the JPL Solar System Exploration office to ask if they'd like me to pursue it. I led the initial science development work. I was involved in choosing our fantastic Principal Investigator (PI) Louise Prockter. Then I became the Project Scientist (PS), who serves as the interface between the science and engineering teams overseeing the science implementation and how the engineers and scientists work together to formulate this complex mission.

So I've been doing that since 2017. Right now [late May 2021], I'm in a gap. We're waiting to hear whether or not we've been selected for probable flight with a launch in 2025 or 2026. So this is a nerve-racking time for me personally because now it's out of my hands. I'm just waiting on the decision from NASA headquarters.

Assuming we're selected, we'll be ramping up as fast as possible. There are a series of reviews before we can launch, and a series of milestones. My job will be to make sure that the science is communicated to the engineers as requirements that they can then go away and implement to ensure that the hardware and the mission design meets the needs of the science community. The science community are represented by our broad science team, which is mostly U.S.-based, but we also have people in Sweden, France, England, Italy, and Israel, all of whom are very engaged.

We have an innovative way to do the mission on a very low budget using some really fantastic hardware. The combined narrow angles camera infrared spectrometer is going to produce some of the most amazing images of the outer solar system that have been seen as well as detailed compositional mapping. Because Voyager 2 didn't carry an infrared spectrometer, we really don't have a lot of details about how the geology relates to the composition on Triton’s surface.

To me, it's a dream mission because it loops back to that thing in the backyard with my dad: the camera lens projecting Halley's comet onto a piece of paper. The camera lens we're going to be using is a lot bigger, and it's going to reveal a lot more information. But it still comes down to how we study these alien worlds.

It's going to be incredible for me personally if it gets funded. It's a dream come true to take a mission concept from the first concept, a little nugget of an idea that was inspired by something I saw in 1989, and to work as part of a very large, diverse, complex team to make it a reality and win the support of NASA. Then to eventually fly it, to collect the data, to plan out this sequence of observations … I think is going to be truly a fantastic experience, and it's something I've been wanting to do for most of my career.

I should say that's not my only job. I keep my science hat on, so I am always doing some level of science, trying to produce meaningful papers. I remain interested and actively involved in geological fluid science.

I love teaching and mentoring as well. I'm the lead science mentor for the NASA Planetary Science Summer School which brings advanced graduate students and postdocs to JPL. We teach them, as a group of scientists and engineers, to work together to design missions in a simulation of the early mission proposal work that we do at JPL. It's a chance to fill in some of the gaps in knowledge for people leaving graduate school to make them truly useful in the mission development environments, and hopefully, make them think about their work in different ways.

To me, teaching scientists and engineers how to work together is really rewarding. A lot of what I do is get people to think from the perspective of other technical cultures, introducing them to different ways of thinking than they may have experienced so far in their careers. It’s a highlight of my year.

What advice you would give to others interested in a similar career?

Go for it! This is what I have done throughout my entire career. I get bored unless I'm challenged. Take the exciting opportunities that come your way, but be ready for some twists and turns.

Also, be willing to change your mind because sometimes you realize that what you’re doing is not actually the thing you most want to do. Take those branches in the road that perhaps weren't the most obvious. You're always learning, and so you're always evolving in your aspirations.

Sometimes you just don't get the breaks, and you have to carve out your own path. In 2015, I wasn't getting the mission opportunities I wanted; the stepping stone from Cassini to something new. I made the decision to train myself to create my own mission, to come up with something really new. A lot of what I did for the next year or so was learning how to do that and it worked well for me. But I wouldn’t have succeeded had I not been open to being mentored by people like Bill Smythe at JPL, who generously helped me learn about mission formulation.

Who inspires you?

My father. That experience in the backyard with Halley’s comet was very important. Dad got me interested in thinking.

The people who've inspired me most are always people that I have actually worked with. For me, it's engaging in the actual process with someone and realizing that the way they thought about and tackled a problem was inspirational.

My Ph.D. advisor, Lionel Wilson at Lancaster University, helped me to think as a pure scientist, and got me interested in how to think and why. He really enabled me to bring my intuition of the physical world and my understanding of mathematics into a scientific context.

The best example for me personally of a good leader is Louise Prockter, the Trident Principal Investigator. In addition to her impressive management and leadership experience, and love of Triton, I find that she constantly tries to be better at everything she does. I think she is also way more talented already than she appreciates. I am particularly impressed by her remarkable ability to give an inspiring speech off the cuff, which helps to bring out the admiration, warmth, and loyalty from the entire team. Plus, she knows when to step back: she doesn't micromanage. She always seems to know exactly that right balance of active leadership and just encouraging people.

Steve Wall, who was de facto head of the Cassini RADAR team, was another inspiration because of his efforts to make everyone feel welcome, encouraged, involved, and engaged. He remains someone that I can talk to about leadership when I want to ask how to create a great working environment.

These are just examples. There are so many more, and I feel bad leaving them out, but I truly have been inspired by a lot of people.

What has been your biggest challenge, professional or personal, and how did you overcome it?

The biggest professional challenge has been working on the proposed Trident mission to Neptune – carving out an opportunity from the smallest seed of an idea and training myself on the fly. I have had to constantly learn and adapt. One of the jobs of a Project Scientist is to lead a small team of scientists at JPL and to be honest, I had avoided most management in my career until then. Learning how to get the best out of people, to inspire them, has been very new for me.

On the personal side, during the process of developing Trident – my partner and I adopted a 15-year-old boy. That's been a huge and rewarding learning experience.

What have been some of your favorite projects to work on?

I already mentioned Cassini RADAR, which allowed me to be one of the first to see the surface of an alien world for the first time. It’s hard to imagine anything much more rewarding, but Trident would similar in many ways: With the exception of Eris, which is even further into deep space, Triton has the largest unmapped surface of any planet or moon in the solar system remaining. This might be one of our last true opportunities to explore the surface of an alien world in our solar system. We'll have to go to other solar systems after that, or perhaps underground.

But a lot of what makes a favourite project for me comes down to people. For example, I was on the Cassini science planning team for a couple of years, and while less scientifically rewarding, it allowed me to engage with some of the most fantastic people - Trina Ray, Jo Pitesky, and Bill Heventhal, to name a few – which stood out as one of the most inclusive and supportive environments I’ve been in. I had a great and memorable time.

I have to say though that I’ve had few professional experiences that were not enjoyable; I’m in my dream job after all. The people I've worked under have been generally very helpful and friendly, finding me opportunities to prove myself. I also consider myself lucky that I’ve not experienced directly any abusive managers; I know not everyone is so fortunate.

What are some fun facts about yourself?

One thing I do love doing is caving. I started getting interested in the role of caves in transporting geological fluids because, on Titan, there's good evidence that we have karst, which is a type of terrain on Earth often associated with limestone caves. So I started going to planetary caves meetings and a lot of the people in the meetings were also cavers. I started getting invited out caving by the likes of Penny Boston, now at NASA Ames. So in my spare time, I continue to love to do that, both professionally when I get the opportunity and as a hobby.

I am, like many at JPL, a bit of a nerd. I love science fiction and fantasy. One activity I’m keen to get back to after lockdown is attending elaborately themed costumed balls. In the past, I’ve attended “The Labyrinth Masquerade Ball” based in Los Angeles. Another one is the Edwardian Ball, which is inspired by the artist Edward Gorey.

I was raised vegetarian, and have been vegan for many decades now. My parents were hippies and inspired my love of non-human animals. I do enjoy creative vegan cooking and exploring new flavors.

I'm an in-betweener when it comes to the extrovert/introvert spectrum. Fundamentally I'm probably slightly more an introvert, but I get energy from certain social things as well. However, after I have engaged as an extrovert for a long time, which these big projects often require, I feel a need to get away from people. My favourite way to do this is to drive my Tesla in the middle of nowhere and camp or go caving, something like that. The U.S. Southwest, as someone who comes from the UK, is a paradise for geology, for road trips, for exploring nature. On some level, a lot of what I do comes back to my love of exploration.

What is your favorite space image and why?

The Titan image we call "T16." This was the Cassini radar image where we saw the first lakes on an alien world – the entire scene in which hydrocarbon lakes were first discovered on Titan. I was in the room where it happened.

Cassini noodle
This image shows the entire scene in which hydrocarbon lakes were first discovered on Titan, near its north pole. This image was acquired on July 22, 2006, by Cassini's radar instrument in synthetic aperture mode. Credit: NASA/JPL-Caltech/ASI