Characterization of Meteoroids and Meteors through Simulations and Remote Sensing Using High-Power Large-Aperture Radars

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Approximate 100 tons of extraterrestrial matter, primarily composed of meteoroids, enters the Earth’s atmosphere every day. Meteoroids are defined as solid particles of natural origin in space, which typically originate from the breakup of comets and asteroids and are categorized according to their origin. On average, over 100 billion meteoroids enter Earth’s atmosphere daily with masses larger than 1 microgram. Meteoroids travel between 11 and 72.8 km/s relative to the Earth if in solar orbit; a small, though as yet undetermined, fraction originates outside of our solar system, implying that distant stellar systems can impact Earth’s environment. The light and associated physical phenomena associated with a meteoroid’s passage through a planet’s atmosphere is called a meteor, which results from the plasma created by the meteoroid as it ionizes the gas along its trajectory. Although meteoroids have a profound effect on our space environment, we know very little about their fundamental properties. The connection between meteoroid properties and plasma formation still remains poorly understood due to a lack of knowledge regarding how background properties influence the plasma dynamics and also how selection effects in the observing instrument impacts detection. This project seeks to answer these questions by probing into the plasma physics that surrounds the meteoroid, known as the head echo plasma, and uncover the connection between meteoroid properties, plasma formation, and the properties of the background ionosphere. The research will address many of the outstanding questions in the meteor and meteoroid community, including the mass deposition rate into our atmosphere, the dominant density population, and the effect of the background electric and magnetic fields on plasma expansion and distribution. This fundamental research includes the development of three simulations, including a Direct Simulation Monte Carlo (DSMC) model and a Particle-In-Cell (PIC) algorithm to determine the plasma formation and expansion, and a Finite-Difference Time-Domain (FDTD) model to correlate radar signal strength with plasma density. The project team will also collect and analyze High-Power, Large-Aperture (HPLA) radar data at diverse geographic locations. This research will contribute to the National Space Weather Program’s goal of understanding the evolution of ionospheric irregularities, and answer the following three scientific questions:1) What are the properties of meteor plasmas, including peak plasma density and distribution?2) How is meteoroid ablation and plasma formation affected by the physics of the upper atmosphere and ionosphere?3) What are the properties of the parent meteoroids, including mass, bulk density, and velocity, and how do they correlate to the meteor plasmas?The results of this research will enable understanding of impact plasma and facilitate collaboration between MIT Haystack Observatory and Stanford University. The HPLA data, in addition to the models and simulations developed, will be widely disseminated to enhance scientific and technological understanding. Graduate students will be involved in all aspects of the modeling and simulation, and both undergraduate and graduate student students will be able to analyze the HPLA data, which will contribute to the training of the next generation of scientists and engineers. The research will be integrated into the classroom at Stanford University, including three graduate classes and one undergraduate class designed and taught by the PI. In addition to developing and teaching these courses, the PI frequently engages in outreach activities, such as with grade schools, the Mission to Mars Program for undergraduate students, and various television programs, such as National Geographic, the Weather Channel, and PBS NOVA, where she has described how meteoroids can threaten interplanetary space programs. These endeavors will inspire another generation of students beyond those directly engaged at Stanford University to pursue a degree in this field of research.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.