CAREER: GLOW: Investigation on the evolution of magnetic fields of early Earth and beyond with cutting-edge research opportunities for future scientists

In the inner solar system, Earth is the only terrestrial planet that has a strong magnetic field. The geomagnetic field provides a habitable environment for life by shielding it from harmful high energy particles. Thus, the presence of a magnetic field can help support life on the planetary surface.

Mars appeared to have had a magnetic field in the past based on remnant magnetic fields in the Martian crust. Mercury currently has a magnetic field, but it is approximately 100 times weaker than that of Earth. Venus does not have any indication of a current or past magnetic field.

Some observed planets in extrasolar systems (exoplanets) might have signs of magnetic fields, but further studies are needed. Currently, Earth’s magnetic field is produced by processes in the iron core, which consists of a solid inner core and liquid outer core with some light elements. As Earth cools, the solid inner core grows, releasing heat and light elements to the bottom of the liquid outer core.

This facilitates convection in the outer core and contributes to generating a magnetic field. However, it is likely that this mechanism did not operate in the past because recent studies suggest that Earth’s core was completely molten in the early Earth and the solid inner core did not nucleate until recently (~ 0.5 – 1 Ga). Simultaneously, terrestrial rock records indicate that Earth had a magnetic field by 3.5-4.2 Ga.

This may suggest that early Earth generated a magnetic field in a different mechanism from today’s process. It has been hypothesized that planetary magnetic fields may be influenced by meteorite impacts, but the details are not well understood. In this proposal, the team will investigate the mechanisms of Earth’s magnetic field over its history and apply the model to other planets, including Mars, Venus, and exoplanets, to achieve a comprehensive understanding of planetary magnetic fields.

This will also help understand the habitability of a planet throughout its lifetime. One of the key aspects of the proposal is participation of local high school, undergraduate and graduate students, who will conduct cutting-edge research, numerical simulations, and learn scientific communication. This proposed work will provide a unique and enriching opportunity to a diverse group of students, encouraging them to pursue STEM career paths.

This research will include the following tasks over the next five years to understand the history of magnetic fields of Earth and other planets: (1) Determine the Earth’s initial interior structure. Earth and other planets form by collisions among growing planets. This impact stage determines the initial structure of the planetary core and mantle, which strongly influences whether generation of a magnetic field in the core is likely or not.

The team will calculate the planetary interior structure based on impact simulations using a smoothed particle hydrodynamics (SPH) method, which calculates fluid flows. (2) Using SPH, the team will investigate how meteorite impacts affect the magnetic field of Earth during the Hadean (4.5-4 Ga) and Archean (4-2.5 Ga) era. (3) Conduct shock experiments. The team will investigate the possibility that early Earth’s magnetic field was produced in an iron-rich silicate melt at the core-mantle boundary (basal magma ocean, BMO) instead of magnetic field generation in the core.

For the BMO to generate a magnetic field, the BMO needs to have a very high electrical conductivity, which controls how quickly electrons move in the material. The team will calculate the electrical conductivity of a BMO analogue material based on laser-driven shock experiments at the University of Rochester Laboratory For Laser Energetics. (4) Simulate a magnetic field generation process in BMO using the electrical conductivities estimated in (3) as an input, and (5) apply the model developed for Earth to other planetary bodies, including the Moon, Mars, Venus, and exoplanets to predict the history of their magnetic fields.

The proposed projects will be led by two graduate students and contributed by high school and undergraduate students. Four local high school students will join this project as summer interns and they will learn coding, data visualization, and cutting-edge research during Years 1 and 2. They will be responsible for data visualization of impact simulations, which will be used in paper publications and short public videos.

During Years 3 and 4, the PI will develop a course focused on science communication and research primarily for first- and second-year undergraduate students, where they will learn planetary impact events, science communications, and how to conduct research. The course includes a field trip to the Sudbury impact basin, which is the second largest basin on Earth.

During Year 5, the team will host an exhibit at the Rochester Science and Museum Center (RMSC) to present research output of the team over the past five years.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.