NATHAN J. MCGREGOR

Ph.D. Student in Planetary Science
University of California, Santa Cruz

Cosmochemistry | Rocky Body Formation and Evolution

about // research // publications & presentations // dei // teaching // contact // cv

About

I am a second-year Ph.D. student in Planetary Science at the University of California, Santa Cruz and a member of the UCSC Planetary Science Group studying the origin and evolution of the early solar system. My advisors are Professors Francis Nimmo and Myriam Telus.

I am interested in the formation, chemical differentiation, and geodynamics of rocky bodies (planets, moons, asteroids, etc.), particularly (1) their bulk volatile and moderately volatile element composition, (2) cycling and storage of volatiles in their interiors, (3) delivery and loss processes of these volatiles during early accretion and differentiation, (4) interactions between volatiles and redox processes in magma oceans, and (5) mantle and core geochemistry and petrology. I combine experiments with analytical and theoretical models to date early solar system processes and constrain rocky body evolution scenarios using the isotopic systematics of volatile and moderately volatile elements as well as a variety of analytical tools, e.g., electron microprobe, TGA, EBSD, and LA-ICP-MS.

I received my B.S. in Physics and Astrophysics and B.A. in Political Science from Boise State University. During my undergraduate career, I worked with Professor Daryl Macomb on long-term optical monitoring of BL Lacertae objects and was a member of Professor Brian Jackson’s Planetary Science Research Group.

Research

Venus

Baltis Vallis (BV) is a 6,800-km long lava channel on Venus with a present-day uphill flow direction. A 2000-km wavelength has been identified in its power spectrum (Conrad et al., 2021). This length scale is comparable to the thickness of Venus’ mantle, suggesting that mantle convection is responsible for the observed deformation. Older studies suggest Venus has a surface age of 300 Myr to 1 Gyr (Hauck et al., 1998; McKinnon et al., 1997); however, recent studies estimate a younger surface age of 150 to 240 Myr (Herrick and Rumpf, 2011; Le Feuvre and Wieczorek, 2011). The observed deformation of BV indicates that mantle convection was active over this timeframe and provides constraints on the length scales and vertical amplitudes involved. We place constraints on Venus’ present-day internal structure and dynamics by comparing dynamical topography produced by simulated mantle convection with the topography of BV.

Original and filtered topographic profile of BV. Short wavelengths are removed to highlight the long-wavelength deformation caused by mantle convection. A and A′ mark the inferred source and termination points, respectively (Baker et al., 1992).
Median decorrelation times and RMS heights colored by Ra. The dashed line denotes BV’s RMS height. The shaded region indicates recent estimates for Venus’ surface age (Herrick and Rumpf, 2011; Le Feuvre and Wieczorek, 2011). Error bars are interquartile ranges.
Future Projects

Future work I am interested in includes

  1. An n-body degassing model for my current work on meteorite outgassing to include the effect of accretional vapor loss on planetary compositions.
  2. Modeling the degassing of a disrupted planetesimal core such as Psyche to compare with experimental degassing of iron meteorites.
  3. Constraining the impact origin of Phobos and Deimos by determining the amount of depletion of volatiles from the building blocks of the Martian moons after the impact.
  4. Investigating chondrule evolution and accretion to determine if terrestrial planets formed from volatile-poor chondrules and subsequently acquired volatile-rich material under more reducing conditions.

Publications

  • McGregor, N. J., Nimmo, F., Gillmann, C., Golabek, G., Plattner, A. & Conrad, J. W. (2023). Inferences on the mantle structure and tectonic regime of Venus from surface deformation observations. In prep.

Conference Abstracts

  • McGregor, N. J., Nimmo, F., Gillmann, C., Golabek, G., Plattner, A. & Conrad, J. W. (2023). Constraining Venus’ Convection Regime from Baltis Vallis Topography. European Geosciences Union General Assembly. Abstract
  • McGregor, N. J., Nimmo, F., Gillmann, C., Golabek, G., Plattner, A. & Conrad, J. W. (2023). Constraining Venus’ Convection Regime from Baltis Vallis Topography. Lunar and Planetary Science Conference. Poster   Abstract
  • Calderon, T., Jorge-Chavez, F., McGregor, N. J., & Telus, M. (2022). Investigating Mn Rims of Chondrule Meteorites. UC Santa Cruz Research Experiences for Undergraduates Program on Sustainable Materials.
  • McGregor, N. J. & Macomb, D. (2020). Photometric Monitoring of MRK 501: A Model for Measuring the Optical Variability of BL Lacs. Idaho Conference on Undergraduate Research, #131.
  • McGregor, N. J. & Macomb, D. (2020). Photometric Monitoring of MRK 501: A Model for Measuring the Optical Variability of BL Lacs. Boise State University Research Showcase, #119.
  • McGregor, N. J. & Macomb, D. (2012). Identifying X-Ray Sources in Local Group Galaxies Using Fourier Analysis of Time Series Data. Boise State University Undergraduate Research and Scholarship Conference, #22.

DEI & Outreach

I have a strong track record of improving access and opportunity for all by engaging with communities that are underrepresented in STEM, working with students from diverse backgrounds, and participating in community service efforts. I am currently the Graduate Student Representative on the Committee on Affirmative Action and Diversity (CAAD) with the UCSC Academic Senate and a member of two diversity, equity, and inclusion (DEI) groups: a graduate-led group and a Department committee comprising faculty, staff, and a few students.

LGBTQ DEI in science is a deeply personal passion of mine, as I have experienced the feeling of not belonging as an LGBTQ scientist. I strive to help middle school, high school, and university students see a future for themselves in science, and feel welcome and free of discrimination in their respective disciplines, particularly those who identify as LGBTQ. Currently, I volunteer several hours per week with the Queer Youth Task Force of Santa Cruz and Safe Schools Project of Santa Cruz County. I work with local K-12 schools and students to encourage and promote their interest in STEM, particularly among underrepresented minorities who are better able to imagine themselves as scientists once they see it is possible. Working with youth is especially rewarding, as their passion and curiosity is invigorating. Helping them see there is a place for them in science where they are celebrated and welcomed instills them with confidence that motivates them for years to come. I continue to develop solutions for challenges faced by LGBTQ scientists and youth, and to make science safer and more inclusive for all.

Teaching

Teaching Assistant, University of California, Santa Cruz
  • EART 111, Mathematics in the Earth Sciences, Fall 2023
  • EART 111, Mathematics in the Earth Sciences, Fall 2022
Lab Instructor, Boise State University
  • PHYS 212L, Physics II with Calculus, Summer 2021
  • PHYS 105, Stars and Cosmology, Spring 2021 (2 sections)
  • PHYS 101, Introduction to Physics, Fall 2020
  • PHYS 111, General Physics I, Summer 2020
  • PHYS 111, General Physics I, Spring 2020
  • PHYS 112, General Physics II, Fall 2019
Teaching Assistant, Boise State University
  • PHYS 341, Classical Mechanics, Spring 2021
  • PHYS 111, General Physics I, Spring 2020
  • PHYS 111, General Physics I, Fall 2019
  • MATH 170, Calculus I, Fall 2013
  • MATH 175, Calculus II, Summer 2012
  • MATH 170, Calculus I, Spring 2012
  • MATH 170, Calculus I, Fall 2011

Contact

University of California, Santa Cruz
Earth and Planetary Sciences
1156 High Street
Santa Cruz, CA 95064
njmcgreg@ucsc.edu