For over 500 days, the Hyper-Angular Rainbow Polarimeter 2 (HARP2), a high-tech instrument built by UMBC researchers and students, has been orbiting Earth on NASA’s Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) satellite, capturing stunning data about our planet’s atmosphere, surface, and oceans. UMBC celebrated this milestone with lab tours, a poster session showcasing student research, and talks from the PACE instrument and science teams and university leadership, highlighting the instrument’s success and the hands-on role students play in this NASA mission.

“There is palpable pride on our campus in UMBC’s contributions to the PACE mission,” shares Karl V. Steiner, vice president for research and creative achievement. “Because much of the HARP2 instrument was created with strong involvement from both undergraduate and graduate students, this mission truly combines the best of our research and education missions. HARP2 is clearly a milestone in our 30-plus year partnership with NASA Goddard.’’   

Karl V. Steiner, vice president for research and creative achievement, commended the HARP2 team at the celebration. (Brad Ziegler/UMBC)

HARP2’s story builds on UMBC’s earlier work with the original HARP, a pint-sized CubeSat launched in 2019 that earned the American Institute of Aeronautics and Astronautics’ SmallSat Mission of the Year award in 2021. That tiny satellite showed the world how capturing data from many angles could reveal a more complete picture of the atmospheric composition, including the roles of clouds, dust, and smoke. 

HARP2, launched in February 2024, takes HARP’s work further, collecting detailed data from a survey of the entire globe every two days. HARP2 collects in half a day the same amount of data collected by HARP in its entire two-year flight. Researchers have also enhanced data analysis methods, allowing scientists to glean even more accurate and detailed information from the raw data transmitted from space. Alongside PACE’s Ocean Color Instrument (OCI), HARP2 is helping scientists study everything from air quality to climate patterns, and painting a fuller picture of Earth’s systems.

Left: Physics Ph.D. student Emily Faber presents her research on climate modeling at the 500 Days of HARP poster session. Right: Physics Ph.D. student Greema Regmi discusses her work on atmospheric dust with her mentors, Reed Espinosa (left) and Vanderlei Martins (right) at the event. (Brad Ziegler/UMBC)

What sets HARP2 apart is its ability to see the atmosphere in 3D-like detail, thanks to its unique “hyper-angular” views. “The instrument is working, it’s producing great data, and the community is starting to use it,” shares Vanderlei Martins, director of the Earth and Space Institute (ESI) at UMBC and the HARP team lead. Scientists across the U.S. and beyond are tapping into HARP2’s data to track pollution, measure cloud droplet properties, and more. Unlike other satellites, HARP2 can distinguish whether particles in the air are smoke, dust, or pollution, offering clues that help us understand air quality and climate impacts.

To ground-truth the data coming from HARP2, some members of the team traveled to Bolivia. They flew drones over high-altitude Lake Titicaca and the Salar de Uyuni salt flat to collect data that complements HARP2’s space-based views. With less atmosphere above them, these sites offer a clearer match to satellite observations, helping refine the science.

An “explosion” of science

Students at UMBC are deeply involved, from building and calibrating HARP2 to digging into its data. Graduate students in the atmospheric physics program work closely with faculty and NASA engineers, even on the most sensitive elements of the project. 

During testing for HARP2, “I was given the opportunity not only to see the initial calibration process, but then to see the team respond to a catastrophic failure, and then come back from it,” recalls Rachel Smith, an atmospheric physics Ph.D. student. “To watch them come together in support of the project and not miss a beat putting it back together was really incredible to see.” Early in her time with the group, Smith got to hold the instrument. “It’s a cool feeling, that I picked up and worked on this thing that’s now in space,” she says.  

Lab tours in the UMBC Physics Building led by faculty and student researchers were a highlight of the celebration event. (Brad Ziegler/UMBC)

Nirandi Jayasinghe, another atmospheric physics Ph.D. student, recalls the earliest data coming in. “We were all here—graduate students, scientists, and engineers—in this very room, doing stuff piece by piece to visualize ‘first light’ from HARP2,” she says. “I don’t think I’ve seen this much synergy between people anywhere else.”

Over time, the team has grown to meet the rising demands of the project. “I’ve seen how the group has gone from just me, Dominik [Cieslak], Roberto [Borda], and a couple of other engineers to now three, four, five grad students at once tackling different and interesting science questions,” shares Brent McBride ’14, physics, Ph.D. ’22, atmospheric physics, who today is an instrument scientist with the ESI. “It’s been an explosion of not only the capacity of the group, but the science that we’re capable of doing.” 

“There’s huge power there”

“Because of its hyper-angular capability, there are things we can see with HARP2 that we have never seen before,” Martins explains. This includes new insights into cloud properties and aerosol types, which are critical for understanding climate and pollution. HARP2 also helps OCI see past atmospheric haze, boosting studies over land and water. 

Left to right: Vanderlei Martins, Roberto Borda, and Dominik Cieslak have been core members of the HARP team since its earliest days. Here they stand with the HARP cubesat, the precursor to HARP2. (Marlayna Demond ’11/UMBC)

HARP2 has been rock-steady since launch, with no major issues. It even uses the moon for monthly calibration checks to keep its data sharp. Designed for at least three years but with fuel for potentially a decade, it’s poised to keep delivering. The data is freely available, sparking discoveries worldwide. 

“HARP2 is helping us monitor and understand Earth’s systems and come up with ways to improve life,” Martins says.“We can study everything from fires to red tides and even floods, all the way from natural disasters to the effect of pollution on nature in general. There’s huge power there.” 

As the team celebrates HARP2’s more than 500 days in orbit, its steady stream of data continues to fuel discoveries that deepen our understanding of Earth’s atmosphere and oceans. From its roots as a small CubeSat to its role in NASA’s PACE mission, UMBC’s HARP2 showcases the power of collaboration among students, scientists, and NASA, driving science that informs everything from air quality forecasts to climate solutions. With years of potential ahead, HARP2’s impact is only beginning to unfold, inspiring new questions and innovations from UMBC’s campus to the global scientific community.

Attendees enjoyed a festive cake at the 500 Days of HARP2 celebration. (Brad Zielger/UMBC)