Edgar Villegas is among the Spring 2025 RSI Center for Planetary Origins to Habitability (CPO2H) graduate fellowship awardees for his novel research. He seeks to explore how impact processing of asteroids aids our understanding of historical and dynamical evolution of the planetary bodies that make up our solar system. The results of his work may also address outstanding questions about the habitability of early Earth and defense of future Earth.
"My undergraduate major was astrophysics, but I really wanted to do experimental work. When I decided on graduate school, I chose rock deformation. But in the back of my head, I've always been thinking about how to merge the two fields in some way."
So what do astrophysics and rock deformation have in common? Impacts!
Impacts and shock wave physics, which describe the crater forming asteroid collisions we see on the Earth and moon, are an interdisciplinary conjunction of planetary science research. Villegas wanted to somehow combine those aspects of planetary science and hardcore experimental rock deformation. "I essentially thought perhaps I might discover a new discipline. Not many people are doing impact experiments, and from my background research on the field, fewer were looking at the influence of fine scale physical properties on the cratering process when asteroids impact other asteroids."
As part of Villegas' thesis committee, tribology (study of friction and wear between surfaces) engineer Dr. Mathew Brake from Rice Mechanical Engineering, offered two tantalizing tools that might help Villegas realize his goal; an electromagnetic cannon and a light gas gun on loan from NASA.
“It turns out that [Matthew] wanted to conduct impact experiments, and so I devised the project and pitched it to him. He liked the idea.” After some refinement and discussions with EEPS faculty advisor Dr. Melodie French, Villegas now had his dream research project.
The project
Asteroids are not just relics of our solar system’s formation, according to Villegas, they are also proving grounds for impact dynamics that we can learn from. We can observe from both ground-based and orbital telescopes that impacts are the primary dynamical activity that has shaped- and continues to modify- the surfaces and interiors of asteroids. Yet significant gaps remain in our understanding of how some asteroid properties govern impact processes and surface evolution. “Specifically, we really don’t know what is happening at the pore scale during impacts,” says Villegas. This is where hardcore experimental rock deformation meets planetary science.
Villegas describes his experiments as “Deformation from the ultra-fast to the ultra-slow”, in reference to high velocity impacts to be made by cannon and gun in the Mechanical Engineering lab and the slow compression he can observe in real time using the GCTS triaxial deformation apparatus in the EEPS rheology lab.
The data he collects will be used to validate and perhaps improve models that previously generalized those smaller-scale properties, enabling astrophysicists and planetary scientists to better understand the history and evolution of these solar system bodies. They will also perhaps better prepare us for the defense of Earth in the event of a future large asteroid impact.
Villegas also pointed to how the project uniquely connects two schools within the Wiess School of Natural Sciences: EEPS and the Department of Mechanical Engineering. These departments are members of the Rice Space Science Institute, whose goals include fostering interdisciplinary collaboration to answer fundamental questions about solar system evolution and habitability.
“By leveraging expertise and resources from both fields, my work will not only advance our understanding of asteroid cratering processes but also strengthen interdisciplinary ties within Rice University,” concludes Villegas.