This profile series introduces scientists who support projects at Caltech/IPAC while carrying out their own scientific research.
In this profile, we feature Wanggi Lim, who initially joined IPAC as a graduate student and is now a staff scientist for the Roman mission.
The Nancy Grace Roman Space Telescope is a NASA observatory designed to address essential questions in the areas of dark energy, exoplanets, and infrared astrophysics. Roman will have two instruments, the Wide Field Instrument (WFI) and the Coronagraph Instrument, a technology demonstration. Compared to the Hubble Space Telescope’s infrared instrument, Roman's WFI has a similar spatial resolution but will cover 100 times the area per pointing. The Coronagraph Instrument will demonstrate technologies needed for future NASA flagship missions aiming to detect Earth-like planets around distant stars, such as the Habitable Worlds Observatory.
Caltech/IPAC’s role in the Roman mission includes the high-level processing of spectral and microlensing data from the WFI, implementing the proposal solicitation and grant management for guest investigators and overseeing the Coronagraph Instrument operations. These functions are carried out at IPAC’s Roman Science Support Center where our featured scientist, Wanggi Lim, works as a staff scientist.
Why and when did you start dreaming about becoming an astronomer?
It was during my school years in South Korea, when the internet was not widely available. My knowledge of the world came from a handful of books, including encyclopedias, and information from mass media. I had always dreamed of becoming a scientist since I was young, but a few events highlighted in the media during my school years sparked my interest in becoming an astronomer. The first was the Shoemaker-Levy 9 comet, which made headlines in 1992. It was pulled into Jupiter's gravity and ultimately collided with the planet. Watching the media coverage of this event for days, I became curious about why this comet was so significant and why its impact mattered so much. This curiosity deepened my interest in solar system bodies. I began borrowing the dormant telescope from my school and observing various celestial objects, mostly the planets. Then, in 1996, Comet Hyakutake graced the night sky. With friends who shared my interest, I observed the comet for the first time with my own eyes. Seeing its intricate details, which I had only read about in books, left me in awe and intensified my desire to learn more about the universe.
Around the same time, on a trip to visit relatives in the countryside with my family, and because we stayed a little later there than usual, I witnessed the Milky Way for the first time as we returned to our home in the city. That night I also saw an exceptionally large meteor, vividly glowing green and blue, as wide as my finger. The memory of its light remains crystal clear in my mind. These experiences left an indelible impression on me and sparked an intense fascination with astronomy. It felt only natural to decide to pursue a career as an astronomer.
What did you do to make this dream become a reality (in school, university, etc.)?
When I entered high school, our school was selected as a pilot institution for advanced science education. By luck, I was able to participate in the Earth Science department, where I served, perhaps due to my outgoing and positive personality, as the student group leader for all three years of high school, organizing various events. The program was similar to Advanced Placement classes in the U.S., where we learned college-level Earth Science (e.g., atmospheric science, geological history of the Earth) and Astronomy, with opportunities to conduct various experiments. Since I had already decided that I wanted to become an astronomer, I focused on observational astronomy for the activities I could organize. Although my observations at the time were not very scientific (we had to decide what to observe and how to observe, etc.), they were fueled by a great passion and curiosity, which I believe became the driving force that has carried me to where I am today.
Later, when I was preparing for college, I was initially planning to apply to the physics department at the University of Illinois Urbana-Champaign, but when I reviewed the Statement of Purpose that I had written, I realized it was almost completely focused on astronomy, so I briefly considered rewriting it. Eventually, I decided to just apply to the astronomy department at the same university. After entering as an astronomy major, I ended up double-majoring in physics. Looking back, I'm glad I made that decision, because if I had entered as s physics major, I doubt I would have explored astronomy as deeply, given the breadth of physics. Of course, my grades in astronomy were much higher than in physics throughout my undergraduate years!
How did you end up at IPAC? What do you like most about working at IPAC?
After my undergraduate degree I went back to South Korea and worked as a research assistant at Korea Astronomy and Space Science Institute (KASI). I learned about massive star formation there and who were the big names in the field. Thus, I learned about Professor Jonathan Tan at the University of Florida (UF) and checked out the astronomy program there. It looked good, and so I decided to apply and was admitted to the UF astronomy doctoral program. Being a big sports fan (and now a Gator fan), it didn’t hurt that UF had a highly rated overall athletic program as well.
My first connection with IPAC was through the Caltech/IPAC Visiting Graduate Student Fellowship during my second year as a Ph.D. student at the University of Florida. At the time, I had just published my first paper on the dust properties of extreme star-forming environments using mid- to far-infrared extinction maps. Eager to deepen my understanding of dust emission methodologies, I applied for the fellowship and had the privilege of working with Dr. Sean Carey, a pioneer in infrared dark cloud research. The six-month experience not only advanced my research but also left a lasting impression due to IPAC's supportive and collaborative atmosphere. One particularly memorable moment was learning that my wife was expecting twins during my time there, making the experience even more meaningful.
After completing my Ph.D., I joined the SOFIA Science Center at NASA Ames (where again I ran into several Gators or UF graduates), where the skills I gained at IPAC proved invaluable for my research on massive star-forming regions and led to my promotion to Instrument Scientist. While SOFIA was an incredible mission, I wanted to contribute to a new project from its early stages. Hearing that IPAC was recruiting for the Roman Space Telescope reignited my desire to return to IPAC. Since returning, I've been continually amazed by IPAC's unparalleled opportunities to collaborate with world-class scientists, to contribute to groundbreaking missions, and to access cutting-edge scientific results. The supportive environment, especially for early-career researchers, makes me incredibly proud to be part of this extraordinary community.
Tell us briefly about your functional work at IPAC.
At IPAC, I support the Roman Space Telescope mission, a NASA flagship mission conducted in partnership with multiple institutions. IPAC serves as the Science Support Center (SSC) for Roman which is designed to be the most powerful near-infrared survey space telescope so far. The mission will conduct three core community surveys and one General Astrophysics Survey. My primary role involves serving as SSC's liaison to survey definition committees for the Roman Mission, focusing on the Core Community Survey Committee for the Galactic Bulge Time Domain Survey and the committee for the General Astrophysics Survey of the Galactic Plane. I provide science center support in their formulation of survey designs and scientific objectives.
To support SSC’s functional responsibilities in the mission, I work with the Microlensing Science Operations System (MSOS) pipeline team, focusing on pipeline test design and data simulations. Additionally, I contribute to the Roman Space Telescope Proposal System (RTPS) and Community Engagement teams, in which I help with designing the proposal processing system and writing Roman
documentation.
What are the best memories from your career (including your student years) so far?
The best memories of my career and life are undoubtedly the births of my children, which may seem unrelated to my career at first glance. However, these experiences, and everything they have taught me, have shaped not only my life but also my career. When my twins were born, everything felt new and extraordinary. Each moment brought fresh challenges, balanced by immense emotional rewards. When my third child arrived, I expected my prior experiences to prepare me, but I was amazed to encounter entirely new challenges. Even now, I am continually in awe as I witness my children grow and reveal new facets of their personalities.
Interestingly, I find meaningful parallels between raising my children and advancing my research or supporting a mission. Both present a constant stream of challenges, yet these efforts consistently lead to personal growth and contributions to a broader community. This shared journey of discovery, progress, and fulfillment is something I deeply treasure in both my personal and professional life.
Combined images spanning the near- to far-infrared wavelength regime, taken by the Spitzer, SOFIA, and Herschel observatories, focusing on a nearby starburst region (M17, also known as the Swan Nebula). While white represents stars, blue, green, and red colors highlight interstellar dust that is sensitive to varying environmental temperatures. A related study revealed that individual star-forming clusters developed independently, with less correlation in star-forming activities among protostellar clusters than previously suggested. Credit: NASA/SOFIA/De Buizer/Radomski/Lim; NASA/JPL-Caltech; ESA/Herschel.
What is your goal science-wise?
As a scientist, one thing I am certain of is that the goal for me and my fellow researchers is to understand where we came from and where we are headed. Each scientist chooses a different starting point to contribute to this shared pursuit, and I believe that as long as we move in the right direction, we will ultimately converge at the same destination. My chosen starting point is studying Galactic massive star formation, which fascinates me because of its potential to serve as a foundation for understanding not only Galactic ecology but also the formation sequences of the first stars in the universe and the mechanisms behind the formation of supermassive black hole seeds. In many ways, unraveling the mysteries of massive star formation offers a bottom-up approach to explaining the origins of the universe.
Through my research on massive star formation and the dust properties of the dense interstellar medium, I have come to realize that understanding dust properties provides a top-down pathway to exploring planetary system formation. As such, my goal is for my work on the interstellar medium and (massive) star formation to bridge the gap between planetary science and cosmology. Even if this goal isn't fully realized during my lifetime, I hope to provide a strong foundation for future researchers to build upon.
