Rob Zellem

Rob Zellem was interested in astronomy as far back as he can remember. But the moment that cinched his plan to become a NASA astronomer came in high school, when he saw a Hubble Space Telescope image of the Pillars of Creation. 

“It was mind-blowing that something like this could exist in the universe at such a grand scale,” Rob says. “And it was beautiful and amazing just to look at, but the science behind it was even more incredible.” Embedded in the cosmic cloudscape, new stars are bursting to life –– stars that could develop into entire solar systems like our own!

Now, Rob works as the communications scientist for NASA’s Nancy Grace Roman Space Telescope, helping to translate and relay the mission’s science to the public. “It’s come full circle, and now I get to give back and maybe help inspire another generation of kids to get interested in astronomy,” he says.

Watching Other Worlds

Rob’s path to his current role took him from his hometown in Hendersonville, Tennessee to Hawaii and London and many places in between. 

By the end of high school, his love for space was cemented. He had participated in his school’s astronomy club, where they had stargazing parties and even worked on building their own telescope. He knew he wanted to make a career out of it, so he obtained a bachelor degree in astronomy from Villanova University in Pennsylvania.

Then Rob studied abroad, earning a master’s degree in space science from the University College of London. After that, he traveled back to the U.S. to get a Ph.D. in planetary science at the University of Arizona. 

As a graduate student, Rob studied exoplanet atmospheres. For the latter, he used NASA’s now-retired Spitzer Space Telescope to observe an exoplanet (a world beyond our solar system) for around 100 hours and map its weather. 

“I remember being struck by the fact that I was one of the first people in the world to measure that planet’s heat patterns,” Rob says. “It was extremely gratifying to be able to discover something so interesting and really contribute to the scientific community.”

He also observed exoplanets using the ground-based Kuiper Telescope, originally built for Gerard Kuiper –– the astronomer for whom the Kuiper Belt beyond Neptune is named.

“That telescope was built decades before exoplanets were ever discovered, so it was amazing to be able to use it to study them in detail,” Rob says.

Nowadays, Rob does most of his observing remotely. “The most important tool in my toolset is my laptop,” he says. Thanks to modern technology, “I can study space from my couch in my pajamas!”

All Roads Lead to Roman

After completing his Ph.D., Rob became a postdoc at NASA’s Jet Propulsion Laboratory (JPL). He studied exoplanets as they transited (crossed in front of) their host stars, did more ground-based observations, analyzed exoplanet atmospheres, and worked on proposals for future missions like CASE (Contribution to Ariel Spectroscopy of Exoplanets), which will be part of the European Space Agency’s Ariel (Atmospheric Remote-sensing Infrared Exoplanet Large-survey) mission.

Still at JPL, he then became the science calibration lead for Roman’s Coronagraph Instrument, which is designed to demonstrate the technology needed to photograph worlds and dusty disks around nearby stars with unprecedented detail. He was also the project science public outreach lead, communicating the incredible impact this instrument will have on the study of exoplanets. 

Rob also started and leads a citizen science project called Exoplanet Watch, which enables anyone to contribute to exoplanet science. Using just their smartphone, each participant can learn to gather, analyze, and submit data about far-flung worlds using ground-based telescopes. 

Most recently, Rob became the Roman communications scientist at NASA’s Goddard Space Flight Center. When it launches by May 2027, the mission will explore everything from the outskirts of our solar system to the edge of the observable universe. Rob’s job is to help ensure the Roman team conveys all of that science and its potential impact in a way that both the scientific community and the public can understand. 

He takes cues from the likes of Derrick Pitts at The Franklin Institute. “He has really inspired me with both his amazing way of disseminating information to the public and also conveying his own excitement so contagiously,” Rob says.

Rob looks forward to using his similar skill set as Roman prepares for a flood of cosmic data. 

“Roman’s data will be made public immediately after it is processed, which is rare for a space telescope,” he says. “That means it’s really going to be a telescope for everyone, since anyone with internet access will be able to use it right away. It will hopefully be very transformative for the field, especially in terms of making data access more equitable.” 

To others who hope to find their own pathway to astronomy or NASA, Rob suggests leaning into your curiosity and letting it drive you to learn more about the things that interest you most. Then if obstacles arise, you’re more driven to find a way around them.

“I wasn’t the best at physics or math growing up,” Rob says. “I actually failed my first high school physics exam, but I used that to motivate myself forward because I knew I’d have to figure that out to study astronomy.” 

The same mentality has helped him jump into different projects throughout his studies and career. Even if he wasn’t initially an expert on their subject matter, he was determined to figure out a way to contribute.

“Curiosity is a powerful force, both within science and just in general,” Rob says. “It’s a catalyst for discovery and encourages people to cultivate new skills, find new solutions, and develop a deeper understanding of the world around them. That all makes life so much more interesting and enjoyable.”

By Ashley Balzer
NASA’s Goddard Space Flight Center in Greenbelt, Md.