Planetary Science Laboratory
Department of Earth and Environmental Sciences
Department of Physics and Astronomy
University of Rochester
We are studying origin and evolution of planets and moons in the solar system and beyond.
Scott D. Hull
The Moon likely formed from the gravitational collapse of a dust and vapor disk created by a "giant impact" event in which the Earth and a Mars-sized body collided. I use smoothed particle hydrodynamics (SPH) simulations to model real-time giant impact events with the Earth, and then assess both the dynamics and the geochemical outcomes of the model. These studies have implications for understanding the energies and dynamics required to form the observable Earth-Moon system and for understanding the Mars-Moons sytem, which may have formed in a similar fashion.
I am a first-year graduate student at Johns Hopkins University and a former undergraduate at the University of Rochester. I have a broad range of interests in astrophysics and planetary science, and my work with Professor Nakajima was recreating the Vredefort impact, Earth’s largest verified impact crater, using iSALE simulations and comparing those results to geophysical evidence. My PhD work is focused on exoplanets, particularly atmospheres and astrobiology.
The Sudbury Basin is Earth's second largest impact site on Earth, and is one of the best analog sites of an early Earth impact thanks to the preserved impact-induced melt sheet despite its 1.85 billion year old age. I use a shock physics code called iSALE (impact Simplified Arbitrary Lagrangian Eulerian) to computationally recreate this crater. Understanding Sudbury's formation channel enhances our knowledge of geology as a result of catastrophic event which in turn constrains our current interpretation of Earth's formation. My goal is to progress from impact analysis and apply it to research in planetary crustal formation and evolution.
Soren Helhoski (Brown U.)
I was an undergrad at the University of Rochester, majoring in Physics and Astronomy. I have been working on the simulation of large impact events, specifically the Imbrium Basin, using iSALE shock code. Analysis of the ejecta curtains created from each event yields pressure and temperature distributions that can be related to physical evidence.
Jeremy Atkins Undergraduate student, 2018 -- 2021
Pham Nguyen Graduate student, 2019 -- 2020
Tyler Labree REU Summer student, 2019
(co-mentoring with Prof. Dustin Trail)
My goal is to build theoretical models to explain geochemical, geophysical, and astronomical observations. My research focuses on the formation and evolution of terrestrial planets. Click the images below for details!
We constrain the early Earth's condition based on geodynamical models combined with geochemical observations.
We model the origin of the Martian moons, Phobos and Deimos, and make predictions for future missions.
We suggest that whether an exoplanet can form an impact-induced exomoon strongly depends on the planetary mass and composition.
Physics of Planetary Interiors (2019, 2020, 2022)
Geodynamics (2019, 2021)
Designing your space mission (2020, 2021)
According to the canonical model, the proto-Earth was hit by a Mars-sized object approximately 4.5 billion years ago. The movie below shows entropy of the mantle (the extent of shock heating) in the red-yellow colors and iron core in grey. We developed a smoothed particle hydrodynamics (SPH) code from the ground up where a fluid is expressed as a collection of spherical particles.
Feel free to download the movie from here: [canonical - entropy]
It may take a few seconds to load the movies ... please stay patient!
A number of impact models have been suggested, including (1) canonical model, where the proto-Earth is hit by a Mars-sized impactor, (2) fast-spinning Earth model, where the rapidly rotating proto-Earth is hit by a small impactor, (3) half-Earths model, where two half-Earth objects collide, and (4) multiple impact model, where the Moon formed out of multiple small impacts.
We perform numerical simulations to represent (1)-(3) models as below. The green and yellow represent the mantle of the proto-Earth and impactor, whereas grey and white represent their iron cores, respectively.
Feel free to download the movie from here:
Green indicates contributions from the team members
Allen, N., Nakajima, M., Wuennemann, K., Helhoski, S., and Trail, D. Modeling the Vredefort Crater impact with iSALE. Submitted.
Canup, R., Righter, K., Dauphas, N., Pahlevan, K., Cuk, M., Lock, S. J., Stewart, S. T., Salmon, J., Rufu, R., Nakajima, M., Magna, T. Origin of the Moon, New Views of the Moon II. in press.
Nakajima, M., and Genda, H., Asphaug, E. I., and Ida, S. Large planets may not form fractionally large moons. Nature Communications, 2022, in press.
Tarduno, J. A., Cottrell, R. D., Lawrence, K., Bono, R. K., Huang, W., Johnson, C. L., Blackman, E. G., Smirnov, A. V., Nakajima, M., Neal, C. R., Zhou, T., Ibanez-Mejia, M., Oda, H., and Crummins, B., 2021. Absence of a long-lived lunar paleomagnetosphere. Science Advances, 7, eabi7647. [Science Advances]
Nakajima, M., Golabek, G. J., Wuennemann, K., Rubie, D. C., Burger, C., Melosh, H. J., Jacobson, S. A., Manske, L., Hull, S. D. 2021. Scaling laws for the geometry of an impact-induced magma ocean. Earth and Planetary Science Letters, 568, 116983. [SienceDirect][arXiv]
Quillen, A. C., Zaidouni, F., Nakajima, M., Wright, E., 2021. Accretion of Ornamental Equatorial Ridges on Pan, Atlas and Daphnis. Icarus, 357, 114260. [Icarus]
Wright, E., Quillen, A. C., South, J., Nelson, R. C., Sánchez, P., Martini, L., Schwartz, S. R., Nakajima, M., Asphaug, E. 2020. Boulder stranding in ejecta launched by an impact generated seismic pulse. Icarus, 337, 113424. [ScienceDirect]
Quillen, A. C., Martini, L., and Nakajima, M., 2019. Near/far side asymmetry in the tidally heated Moon. Icarus, 329, 182-196. [ScienceDirect]
Nakajima, M., and Stevenson, D. J., 2018. Inefficient volatile loss from the Moon-forming disk: reconciling the giant impact hypothesis and a wet Moon. Earth and Planetary Science Letters, 478, 117-126. [ScienceDirect]
Jacobson, S. A., Rubie, D. C., Hernlund, J., Morbidellie, A., and Nakajima, M., 2017. Formation, Stratification and Mixing of the Cores of Earth and Venus. Earth and Planetary Science Letters, 474, 375-386. [ScienceDirect]
Hauri, E. H., Saal, A. E., Nakajima, M., Anand, M., Rutherford, M. J., Van Orman, J. A., and Le Voyer, M., 2017. Origin and Evolution of Water in the Moon's Interior. Annual Review of Earth and Planetary Sciences, 45, 89-111. [Annual Reviews]
Nakajima, M., and Ingersoll, A. P., 2016. Controlled boiling on Enceladus. 1. Model of the vapor-driven jets. Icarus, 272, 309-318. [ScienceDirect]
Ingersoll, A. P., and Nakajima, M., Controlled boiling on Enceladus. 2. Model of the liquid-filled cracks. Icarus, 272, 319-326. [ScienceDirect]
Nakajima, M., and Stevenson, D. J., 2015. Melting and Mixing States of the Earth’s Mantle after the Moon-Forming Impact, Earth and Planetary Science Letters, 427, 286-95.
Nakajima, M., Stevenson, D. J., 2014. Investigation of the Initial State of the Moon- Forming Disk: Bridging SPH Simulations and Hydrostatic Models. Icarus, 233, 259-267.
Nakajima, M., 2016. Core Science: Stratified by a Sunken Impactor. Nature Geoscience, News & Views, 9, 734-735. [Nature Geoscience]
Nakajima, M., and Stevenson, D. J. Dynamical mixing of planetary cores by giant impacts.