A semi-analytical approach to modeling the configuration of dust ejected from atmosphereless bodies
Thesis event information
Date and time of the thesis defence
Place of the thesis defence
University of Oulu, auditorium L10
Topic of the dissertation
A semi-analytical approach to modeling the configuration of dust ejected from atmosphereless bodies
Doctoral candidate
Master of Science Anastasiia Ershova
Faculty and unit
University of Oulu Graduate School, Faculty of Science, Space Physics and Astronomy
Subject of study
Astronomy
Opponent
Professor Frank Spahn, Institute of Physics and Astronomy, Universität Potsdam, Germany
Custos
Professor Jürgen Schmidt, Institut für Geologische Wissenschaften, Freie Universität Berlin, Germany
Understanding how small particles leave asteroids, comets, and satellites
Small particles in space are usually referred to as dust. Dust plays an important role for many processes in the Solar System, being witness for the evolution of asteroids or comets as well as the composition of potentially habitable environments other than Earth. In recent decades, multiple space missions have collected data on dust. To fully utilize these observations, reliable and efficient methods for analyzing the shape and evolution of dust clouds around the parent objects of the dust are essential.
Instead of tracking individual dust particles separately — a computationally expensive method often employed in cosmic dust research — we developed a mathematical approach that treats the dust as a continuous cloud with statistically described properties. This method enables fast and flexible analysis when certain assumptions about the dominant forces are met. Based on this approach, we developed two software tools: one for dust ejected from moons of the planets where the moon's gravity is the main factor in dust dynamics, and another tool for dust from asteroids and comets, where solar gravity and pressure from sunlight govern the motion.
We applied our first tool to study dust expelled from Saturn’s moon Enceladus, a small icy world known for its ice-volcanic activity. Enceladus is of interest to astrobiologists, owing to the presence of liquid water under its ice crust and the chemical profile of the ejected material sampled by the Cassini spacecraft. Based on Cassini’s data, we modeled the dust cloud of Enceladus, providing estimates of the dust production rate and refining the proportions of dust of different chemical compositions.
The second tool was used to reconstruct the cometary dust tail of the great comet of 1996, the Hyakutake comet, near its closest approach to the Sun, and to investigate the dust environment of the near-Earth asteroid Phaethon. This asteroid is associated with the Geminid meteor shower and has been selected as a target for the Japanese space mission DESTINY+. We estimated the amount of dust that will be sampled by the mission’s dust instrument during the flyby of Phaethon.
Looking ahead, the methods and findings described in this thesis have the potential to contribute to our understanding of the dust environments of many small bodies in the Solar System.
Instead of tracking individual dust particles separately — a computationally expensive method often employed in cosmic dust research — we developed a mathematical approach that treats the dust as a continuous cloud with statistically described properties. This method enables fast and flexible analysis when certain assumptions about the dominant forces are met. Based on this approach, we developed two software tools: one for dust ejected from moons of the planets where the moon's gravity is the main factor in dust dynamics, and another tool for dust from asteroids and comets, where solar gravity and pressure from sunlight govern the motion.
We applied our first tool to study dust expelled from Saturn’s moon Enceladus, a small icy world known for its ice-volcanic activity. Enceladus is of interest to astrobiologists, owing to the presence of liquid water under its ice crust and the chemical profile of the ejected material sampled by the Cassini spacecraft. Based on Cassini’s data, we modeled the dust cloud of Enceladus, providing estimates of the dust production rate and refining the proportions of dust of different chemical compositions.
The second tool was used to reconstruct the cometary dust tail of the great comet of 1996, the Hyakutake comet, near its closest approach to the Sun, and to investigate the dust environment of the near-Earth asteroid Phaethon. This asteroid is associated with the Geminid meteor shower and has been selected as a target for the Japanese space mission DESTINY+. We estimated the amount of dust that will be sampled by the mission’s dust instrument during the flyby of Phaethon.
Looking ahead, the methods and findings described in this thesis have the potential to contribute to our understanding of the dust environments of many small bodies in the Solar System.
Last updated: 9.4.2025