College of EngineeringDepartment of Aerospace EngineeringResearchSeminarsEventsDr. Caleb Fassett, NASA Marshall Space Flight Center

Dr. Caleb Fassett, NASA Marshall Space Flight Center

The Rate of Surface Evolution on the Moon (And Why It Matters)
August 23, 2019


One might expect that landform evolution is limited to airless bodies like the Moon but looking at its surface quickly dispels this idea. Instead, craters infill, hillslopes become rounded, and a thick regolith grows. The main forcing for landform evolution is impact cratering, which turns out to cause topographic diffusion, qualitatively similar to classic models for how hillslopes evolve on the Earth. From new data gathered by Kaguya and the Lunar Reconnaissance Orbiter, the nature, and rate of this diffusional process are now becoming clear. These data reveal that the widely dispersed disturbances caused by ejecta appear to be the primary geomorphic agent on the Moon. Calibration of the topographic diffusivity also allows for new estimates of the age of individual craters and other landforms on the basis of their degradation state, plus the age of surface units. Understanding how the Moon’s surface evolves will be vital as we return to human lunar exploration in 2024 and beyond.


Dr. Caleb Fassett

Planetary Scientist at NASA’s Marshall Space Flight Center. Originally from Maryland, Dr. Fassett earned his BS from Williams College in 2002, and MS and PhD from Brown University in 2005 and 2008, respectively. His scientific research focuses on using a combination of remote sensing, geologic mapping, and numerical modeling to better understand planetary surfaces and geomorphological processes. He is also interested in how observations of impact crater populations can be used to infer the chronology and geologic history of planetary bodies. Dr. Fassett joined the planetary science group at Marshall Space Flight Center in 2016, after 5 years of teaching at Mount Holyoke College. In addition to science, Dr. Fassett supports Center activities, including the Spacecraft and Payload Integration and Evolution team and the Advanced Concept Office. Along with colleagues, Dr. Fassett works with these engineering teams to promote and advocate for science as NASA ventures deeper into our solar system.