The means by which magnetic reconnection in Earth's space environment is observed is limited by current instrument technology and timing of satellite orbits. Imaging capabilities from a spacecraft platform are still developing, and in-situ measurements are confined to the spacecraft's orbit. The goal of this dissertation is to provide and apply methods by which the spatial extent of magnetic reconnection at Earth's magnetopause can be quantified. An accepted single value, or range of spatial extents of magnetopause reconnection has eluded the scientific community for over half a century.
This dissertation provides two methods by which the spatial extent can be sampled. First, with the development of a CubeSat, the Cusp Plasma Imaging Detector (CuPID). CuPID is built with a wide field-of-view soft X-ray telescope to image the photons resulting from solar wind charge exchange between atmospheric neutrals and high charge-state solar wind ions. During magnetic reconnection at the magnetopause, solar wind ions are routed along field lines to Earth's cusps in the polar regions. In the magnetospheric cusps, these solar wind ions can penetrate deeper into Earth's neutral atmosphere, producing an observable signal for a low Earth orbiting satellite. The design of the CuPID mission and the calibrations of CuPID's instruments are presented. CuPID was launched in September 2021, but did not respond to commanding from the ground. Efforts to modify and improve the ground station led to the discovery of a probable root cause of failure with CuPID's flight radio.
A second method of observing magnetic reconnection utilizes in-situ measurements of plasma populations and magnetic fields. The THEMIS mission, orbiting five satellites continuously since 2007, traverse the magnetopause nearly every orbit when their orbital apogee is on the dayside. When two spacecraft cross the magnetopause simultaneously and both observe features of magnetic reconnection, the spatial extent of reconnection is constrained by their spacing. Using statistics from 174 events of spacecraft conjunctions at the magnetopause, the spatial extent of reconnection as observed by THEMIS is on average 3,148 km. This study also investigates the processes by which magnetic reconnection is constrained, including plasma beta gradient drifts and position on the magnetopause flanks.
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/45457 |
| Date | 16 January 2023 |
| Creators | Atz, Emil A. |
| Contributors | Walsh, Brian M. |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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