Research Overview

I am interested in the physical and chemical processes that shape the formation and evolution of planets, moons, and small bodies. My research combines laboratory experiments and numerical modeling to investigate how planetary materials release gases, how interiors influence surfaces and atmospheres, and what chemical and isotopic signatures reveal about a body’s history. These questions connect planetary science, geophysics, cosmochemistry, and astronomy, with applications across our Solar System and to exoplanets, exomoons, and protoplanetary disks.

View my CV
Contact: nmcgregor@ucsc.edu

Research Interests

• Formation and thermal evolution of planets, moons, and small bodies
• Experimental petrology and the chemical and isotopic records of planetary formation
• Volatile storage, evaporation, outgassing, and interactions among interiors, surfaces, and atmospheres
• Water circulation, mineral alteration, and the transport and preservation of organic compounds inside rocky and icy bodies
• Mantle convection, magmatism, and the evolution of planetary interiors and surfaces

Current Research

• Phobos formation and volatile evolution. Did Phobos form from debris produced by a giant impact on Mars, or was it an asteroid captured by Mars’s gravity? I model how impact-generated fragments cool, crystallize, and lose elements through evaporation. My calculations show that fragments can develop surfaces strongly depleted in sodium while retaining most of their original sodium overall. Changes in potassium isotope ratios provide another record of the evaporation conditions. These predictions could help interpret future samples from JAXA’s Martian Moons eXploration (MMX) mission.
• Meteorite outgassing and exoplanet atmospheres. I conduct heating experiments on chondritic meteorites to measure changes in sample mass and the composition of released gases. These experiments investigate how a material’s composition and heating history affect outgassing. By connecting laboratory measurements with models of planetary interiors and atmospheres, I examine how rocky planets’ starting materials influence the atmospheres they develop.
• Venus’s interior dynamics. I use StagYY mantle-convection simulations to investigate how material flows inside Venus and how that motion affects the planet’s surface and orientation. Comparisons with Magellan gravity data help constrain mantle viscosity and the strength of convection. I also investigate true polar wander—the reorientation of the solid planet relative to its rotation axis.

Publications

• McGregor, N. J., Nimmo, F., Hyodo, R., Genda, H. (In prep). Thermochemical and isotopic evolution of Phobos-forming debris across giant-impact scenarios. Icarus.
• McGregor, N. J., Nimmo, F., Gillmann, C., Golabek, Lourenco, D. L. (In review). Rates of true polar wander on Venus driven by mantle convection. J. Geophys. Res. Planets.
• McGregor, N. J., Thompson, M. A., and Telus, M. (In review). Linking rocky exoplanetary atmospheres and interiors through meteorite outgassing. Nature Astronomy.
• McGregor, N. J., Nimmo, F., Gillmann, C., Golabek, G. J., Plattner, A. M., and Conrad, J. W. (2025). Probing the viscosity of Venus’s mantle from dynamic topography at Baltis Vallis. J. Geophys. Res. Planets.

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About me

• Bio. I grew up on my family’s fourth-generation farm in Filer, Idaho, and was the first in my family to leave the farm to pursue higher education. I began my undergraduate education at the College of Southern Idaho before transferring to Boise State University, where I earned a B.S. in Physics and Astrophysics and a B.A. in Political Science, with minors in Applied Mathematics and Criminal Justice. I am currently a Ph.D. Candidate in Earth and Planetary Sciences at the University of California, Santa Cruz, working with Francis Nimmo and Myriam Telus.
• Teaching. Teaching is central to my work. I have taught physics, astronomy, mathematics, and geology as a course instructor, laboratory instructor, and teaching assistant. I use collaborative problem solving, hands-on investigations, and student feedback to help students develop confidence and become independent learners. My own path through community college as a first-generation, LGBTQ student shapes my commitment to educational access and belonging in science.
• Undergraduate Research and Mentoring. Working closely with undergraduate researchers is central to the career I want to build. I have mentored five undergraduates, including three in research, helping them explore their interests, develop projects, and communicate their findings. My research offers opportunities in laboratory experiments, numerical modeling, and data analysis. I work with students to set achievable milestones and encourage them to take greater responsibility as their skills develop. I also help them prepare presentations, manuscripts, and applications for their next career steps.