This profile series introduces scientists who support projects at Caltech/IPAC while carrying out scientific

Kevin Hardegree-Ullman

Assistant Scientist

Link to article: https://www.ipac.caltech.edu/meet-the-staff/kevin-hardegree-ullman 

In this profile, we feature Kevin Hardegree−Ullman, who supports the NASA Exoplanet Archive at IPAC. 

1. You are starting as the new IPAC student coordinator. Congratulations! How would you like to improve the students' experience at IPAC?

Thank you. 

Throughout my work and studies, I have been a strong advocate for students by building programs to strengthen both their research and connections to their peers and mentors. I will solicit regular feedback from students and mentors to help shape and improve future student experiences. I plan to introduce new professional development opportunities for students to work on presentation skills, network with other IPAC students and staff, and learn about different career paths of people who have gotten astronomy degrees. I specifically want to stress the importance of networking. 

2. Did anything from your childhood spark your interest in space, or did you decide to pursue an astronomy career later in your life?

I can't pinpoint a single event from my past that pushed me toward a career in astronomy, but there are several things that likely pushed me in that direction. My dad was a research scientist for the USDA for his entire career, so I was exposed to science most of my life. 

Growing up in the early 1990s, most of my memories of science education are from TV programs. We didn't have cable TV, but PBS had some great programming for kids. I remember the very first episode of The Magic School Bus, where Ms. Frizzle and her class explored the solar system, and I was absolutely hooked. After school, I would come home and watch Bill Nye the Science Guy, who furthered my curiosity about the natural world and helped me develop a passion for teaching science. 

It's incredible to reflect all these years later how much of an impact these National Science Foundation and Department of Energy-funded kids TV programs had on me and my generation. Curiously enough, although I grew up watching Star Trek with my dad, I wasn't too much into reading science fiction books.

I also distinctly remember a unit on the solar system at my elementary school where my teachers were showing incredible brand-new images of Jupiter and its moons from the Galileo spacecraft. We shifted to an extended unit about Mars because the Mars Pathfinder mission had recently launched. I thought the Pathfinder airbag landing system seemed outlandish at the time (only to be superseded 15 years later by the outrageous sky crane that landed Curiosity), but I remember watching the first panoramic images from Pathfinder and the deployment of the Sojourner rover and it gave me chills.

3. What was your education and career path before coming to IPAC?

I am not the first or only astronomer in my family. My older sister Emily and younger brother Michael also have degrees in astronomy, and all of us went to the University of Arizona as undergraduates.

Throughout my time as an undergraduate, I worked with Professor Chris Impey to develop various multimedia for astronomy education projects, including video editing, recording lectures on topics like astrobiology, and working on web pages with astronomy educational content where I coordinated ideas and tasks between the astronomers and the computer science students who coded the web pages. I also helped run the campus telescope once a week for students taking astronomy general education classes. 

I went on to become a graduate student at The University of Toledo, where I conducted brown dwarf and exoplanet research with Professor Michael Cushing, and I worked with Professor Jon Bjorkman to build up the campus 1-meter telescope observing team using a peer-mentoring model. 

At the telescope, I took data for high-mass star research, exoplanet transits, and astrophotography. I was very involved in teaching other students the basics of observational astronomy, including how to use the telescope and instruments, how to plan and execute observations, and how to process and analyze the data they collected.

I learned about IPAC through my sister Emily, who was an IPAC Visiting Graduate Student Fellow in 2013. I became a Visiting Graduate Fellow in 2017, working with Dr. Jessie Christiansen on Spitzer follow-up of K2-discovered exoplanets. I was fortunate enough to come back to IPAC in 2018 to work with Jessie as a postdoc on a large K2 exoplanet occurrence rates project that has resulted in eight papers and several new discoveries by our team so far. I also continued my previous work, which led to the discovery of K2-138 g, the sixth and outermost sub-Neptune planet in a planetary system originally discovered by citizen scientists. 

The most exciting moment in my career so far was when I was processing new Spitzer data that had just been downlinked, and I saw a signal which confirmed the presence of K2-138 g. I was the only person on Earth to know this new exoplanet existed (for about 30 seconds until my brother came in from the other room to see why I was so excited.)

This artist's illustration shows the planetary system K2-138, which was discovered by citizen scientists in 2017 using data from NASA's Kepler Space Telescope. Five planets were initially detected in the system. In 2018, scientists (led by Kevin!) using NASA's Spitzer Space Telescope found evidence of a sixth planet in the system. Image Credit: NASA/JPL-Caltech/R. Hurt (IPAC).

In 2021, I went back to The University of Arizona as a postdoc to work with Professor Dániel Apai on simulating the capabilities of upcoming thirty-meter class ground-based telescopes and their potential to detect biosignatures on nearby Earth-like exoplanets using different observing techniques. We concluded that using transmission spectroscopy to detect oxygen is unlikely, but direct imaging combined with high-resolution spectroscopy is more promising for oxygen detection, including in the exoplanet Proxima Centauri b in the star system closest to our own solar system (assuming it has an atmosphere at all). 

In 2024, the ideal position for me opened at IPAC to become a staff scientist working on the NASA Exoplanet Archive.

4. Tell us an astronomy related story from your life.

When I was an undergraduate, I worked with Professor Yancy Shirley as an Arizona/NASA Space Grant Intern on a project to probe star formation in the Serpens North molecular cloud using the Arizona Radio Observatory 12-meter telescope on Kitt Peak. 

I presented my research as a poster at the 218th American Astronomical Society meeting in Boston, for which I received a Chambliss Astronomy Student Award Honorable Mention. I sent an email about this to my advisor, along with a picture of me standing next to my poster, and he forwarded it, along with a congratulatory message to the entire department. The telescope operators at the 12-meter were so excited that they printed the picture out and hung it up in the control room of the telescope. 

To this day (14 years later!), that picture still hangs in the control room.  

5. Tell us about what you work on at IPAC, both project-wise and scientifically.

I am a research scientist supporting the NASA Exoplanet Archive. I work with a small team of scientists and engineers to identify new exoplanets or updated exoplanet measurements from published papers to add to the archive. 

I also work to maintain and improve the archive to support scientists around the world researching exoplanets, and I am helping to prepare for the upcoming deluge of new exoplanet discoveries from missions like NASA's Nancy Grace Roman Space Telescope and ESA's Gaia and PLATO. To help expedite the incorporation of new planet information to the archive, we will soon provide templates to the observers to upload their parameters when their papers have been accepted for publication. 

For my own research, I primarily work on exoplanet demographics (understanding the different types of exoplanets that exist) using data from the Kepler, K2, and TESS missions. Determining properties of exoplanets through indirect means, such as transit observations (where exoplanets cross in front of their host stars from our viewpoint), relies on precisely knowing the properties of their host stars. 

A lot of my work stems from uniform classification of stars using spectroscopy, photometry, and astrometry from both large archival datasets and data I collect myself at various telescopes. I develop and use these large stellar catalogs as a basis to work with teams on projects ranging from discovering new exoplanets and computing exoplanet occurrence rates to predicting the ability of upcoming thirty-meter class telescopes to probe oxygen on nearby Earth-like exoplanets.

6. You returned to IPAC after having spent some time here earlier as a visiting graduate student. How does IPAC compare to other astronomy institutions, and what made you want to come back here?

My previous institutions have all been purely academic settings, where professors both teach and take on students and postdocs to conduct most of their research. At IPAC, scientists don't generally have teaching duties, but they are critical to supporting, operating, and maintaining archives, services, and products fundamental to astronomical research. IPAC also plays a critical role in shaping the future of early career scientists by providing several programs and opportunities for students and postdocs to work on research projects.

This is my third time back at IPAC, so I clearly enjoy working here. 

Everyone at IPAC is very friendly, and I really enjoy the synergy between the scientific, engineering, and support staff. I wouldn't have the strong research and support network I now maintain without the mentors and connections I made at and throughout my time at IPAC.

7. What are your plans as an IPAC scientist? What’s next?

As the field of exoplanets rapidly grows and evolves, in addition to participating in the expansion of the Exoplanet Archive, I want to continue to delve into the depths of exoplanet demographics with data from TESS, Roman, PLATO, and other future missions. 

I am particularly interested in studying M dwarf systems, not only because M dwarfs are the most abundant stars in the galaxy, but also because they are likely the most promising targets around which we will identify an Earth-like planet with biosignatures in my lifetime (assuming their atmospheres aren't all stripped away by their active hosts).

8. What is your life like outside of work? What are your favorite things to do?

Beyond IPAC and astronomy, I spend all my free time with my three-year-old son, my spouse, and our two dogs. We love playing at nearby parks, visiting new science centers and museums, traveling to see our extended family across the country, or just catching up on new or old sci-fi on the weekends. 

As hobbies, I enjoy nature-, landscape-, and astro-photography (with and without a telescope), and I tinker with various projects using a Raspberry Pi minicomputer, including making website servers, interfacing with circuit boards, and building a time-lapse night sky camera.