A Constant Commitment to Research

Leading the science operations of Roman and a research group devoted to ongoing galactic studies.

Roeland van der Marel
Dr. Roeland van der Marel

Throughout his career, Dr. Roeland P. van der Marel has balanced his work on missions like the Hubble and James Webb space telescopes with ongoing research. Now, as the head of the Nancy Grace Roman Space Telescope mission office at the institute, that balance is more important than ever. Here, Dr. van der Marel shares how he came to accept this leadership role and how it fuels his research.

Why did you choose to pursue astronomy?

This field attracted me because it studies the wide, unknown universe and allows me to combine that with very modern, state-of-the-art technology and international collaborations. This profession offers a stimulating mix of endeavors.

How did you end up at STScI?

After I finished my PhD, I applied for a Hubble Fellowship, which placed me at Princeton for three years. Then I transferred to the institute as a Giacconi Fellow before accepting a position in the institute’s science policies division. From there, I spent several years leading the institute’s work on Hubble’s Advanced Camera for Surveys (ACS) and the Wide Field and Planetary Camera 2 (WFPC2). Subsequently, I took on another leadership role in the instruments division, which focused on the segmented mirror optics of the James Webb Space Telescope (JWST).

I started in my PhD as a theorist, not an observer, which is worth pointing out. I became an observer because I needed to improve my understanding of the data and the instruments required to test my theoretical models. I’ve always tried to learn new things, which keeps the work exciting. Every few years, I have had the opportunity to change my role, learn something new, work with new people, and learn about new technologies. In 2014, I was appointed the mission head for the Roman Space Telescope.

Why are you so excited about the Roman Space Telescope mission?

Roman will provide the same image quality as Hubble, but over a field of view that is 100 times larger, which will revolutionize the field of astronomy. For example, consider the search for rare objects. It’s much more likely to find them if you cover a big area.

I have worked on missions that are currently operating, as well as those in various stages of design and development. The nice thing about an operational mission is that it’s bringing down data you can analyze to answer exciting scientific questions. While there are always opportunities for innovation, all systems are already in a mature state. Instead, if you work on a mission in early planning, design, and development phases, you can help scope how the system will operate. It allows you to be very creative and design new approaches to implement the requirements.

Why is ongoing research so important to you?

I am an expert in galactic dynamics (the study of how stars and galaxies move) and what this tells us about their structure, formation, and evolution. For 25 years, I have used Hubble to study the most pressing questions in this subject area, ranging from the study of black holes in the centers of galaxies to collisions between galaxies. Over the past decade, my research shifted from motions along the line of sight (measured from spectra using the Doppler effect) to proper motions (the change in stellar positions on the sky over time). The problem is the universe is very big and stars move slowly. With Hubble, it’s become possible to take sharp images of small fields and compare them from one year to another to see which stars have moved. It might only be one hundredth of a pixel—but you can write sophisticated code to analyze it. The HSTPROMO group that I lead has specialized in this and our research has yielded many important scientific results.

My most recent work has focused on the releases from the European Space Agency’s Gaia mission, which included proper motions for more than 1.3 billion sources over the entire sky. Our group spent months preparing scripts and tools, and discussing analysis methods to have them ready the moment the data were released. Within a month, our team submitted six papers to peer-reviewed journals. It was rewarding to discover in this process that the Hubble measurements we obtained in earlier publications were largely validated, and could be expanded in various ways with the new Gaia data. Although my primary focus now is to work on a mission that NASA will build and fly in the mid 2020s, it’s nice to balance that work with research from different missions that are taking data today. It keeps me engaged with the science drivers and research possibilities for Roman.

Learn more about Dr. van der Marel’s professional background.

Article updated March 2019.