Grant, Samuel R;
(2024)
Identification and analysis of in-situ cometary ion tail encounters.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
The study of the behaviour of comets in the solar wind provides a probe into the heliosphere and the comets themselves. Spacecraft that encounter cometary ion tails can detect cometary ions and magnetic field fluctuations, providing at a significant distance from the comet itself clues to its composition and interaction with the heliosphere. Described here is the development and method of the Tailcatcher program. This provides accurate information on serendipitous spacecraft-comet encounters, using in-situ data to find and refine our understanding of cometary ion tail and coma crossings. Solar wind velocity measurements made by a spacecraft anti-sunward of a comet can be used to extrapolate the flow of the wind back towards the Sun, in which the minimum distance between these extrapolated solar wind packets and known comets is a measure of the likelihood of an ion tail crossing. This method provides a considerably better picture of encounter geometries than available previously, and can uncover previously unknown crossings. Serendipitous ion tail encounters are an almost untapped scientific resource, with the potential to significantly advance the field of cometary physics using pre-existing data and missions. The identification and analysis of these events is presented in this thesis. This work is the culmination of the studies and research completed by the author, unless otherwise referenced. The development and functionality of a method for the prediction of cometary ion tail crossings is presented, and applied to several past encounters. An analysis of encounters with the ion tail of comet 73P/Schwassmann-Wachmann 3, as submitted for publication, is presented as evidence for the existence of ion sheets resulting from extended cometary debris trails. Analyses of two ion tail crossings by Solar Orbiter, the latter predicted by the author, are presented, focussed on the pitch-angle distributions of suprathermal electrons and magnetic field draping.
Type: | Thesis (Doctoral) |
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Qualification: | Ph.D |
Title: | Identification and analysis of in-situ cometary ion tail encounters |
Open access status: | An open access version is available from UCL Discovery |
Language: | English |
Additional information: | Copyright © The Author 2024. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
URI: | https://discovery.ucl.ac.uk/id/eprint/10202430 |
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