MODIS · Earth observation
Solar-diffuser calibration after orbital drift
The problem. Terra and Aqua are drifting away from the orbital planes they maintained for most of their missions. The changing geometry pushes solar-diffuser observations outside much of the range characterized before launch and early in the missions.
My part. I co-led a 2022 study of calibration strategies for the post-drift regime. Later team work examined the continuing drift and used additional Aqua yaw maneuvers in 2024 to characterize the changing illumination.
Why it matters. The objective is straightforward: keep the reflective-solar-band Level-1B calibration reliable as these long-running instruments move into a part of their orbital life that was not part of routine operations for most of the mission.
VIIRS · Earth observation
Day–night-band calibration and performance
The problem. The VIIRS day–night band measures scenes from daylight down to very low light using three gain stages. The gains, gain ratios, and on-orbit changes all have to stay characterized.
My part. I currently support DNB calibration for NOAA-20 and Suomi NPP. Collaborative work also covers NOAA-21 performance, and I presented the DNB calibration update at the 2026 MODIS/VIIRS Calibration Workshop.
Why it matters. A stable calibration is what makes low-light observations comparable across time and across instruments rather than simply producing attractive nighttime images.
Comets · Planetary science
A dynamical Gateway into the Jupiter-family comets
The question. How do trans-Neptunian objects evolve through the Centaur population and into Jupiter-family comet orbits?
What we found. Numerical orbital integrations identified a short-lived, low-eccentricity Gateway just outside Jupiter through which the majority of the modeled Jupiter-family-comet progenitors passed. The highly active Centaur 29P/Schwassmann–Wachmann 1 occupies that region today.
Why it matters. The Gateway overlaps a distance range where cometary activity becomes more common, giving us a place to study the dynamical and physical transition together rather than as separate problems.
Asteroids · Planetary science
Ejecta in a Didymos-like binary system
The question. In a binary asteroid system, which properties most strongly control where impact ejecta goes and how quickly it returns to a surface?
What we did. A 2024 study simulated 72 variations of the Didymos system, changing system separation, mass ratio, impact location, target shape, and rotation period, then grouped the resulting spatial distributions and surface-return histories.
Why it matters. The results provide a baseline for predicting ejecta behavior in binary systems and show, for example, how strongly rotation period can control the outcome.