View in EDS

Modeling the Detectability of Energetic Heliospheric Ions at Pluto During the New Horizons Flyby.

Saved in:
Bibliographic Details
Title: Modeling the Detectability of Energetic Heliospheric Ions at Pluto During the New Horizons Flyby.
Authors: Ruch, Randall T.1 (AUTHOR) randy.ruch@eas.gatech.edu, Simon, Sven1,2 (AUTHOR), Kollmann, Peter3 (AUTHOR), Haynes, C. Michael1 (AUTHOR)
Source: Journal of Geophysical Research. Space Physics. May2026, Vol. 131 Issue 5, p1-29. 29p.
Subject Terms: Magnetosphere, Pluto (Dwarf planet), Particle detectors, Ion energy, Helium plasmas
Company/Entity: New Horizons (Spacecraft)
Abstract: We investigate the detectability of heliospheric helium ions at energies up to 100 keV by the New Horizons (NH) spacecraft during its flyby through Pluto's induced magnetosphere. The Pluto Energetic Particle Spectrometer Science Investigation energetic ion detector observed a reduction in their flux by an order of magnitude as the spacecraft passed through the non‐uniform electromagnetic fields near the dwarf planet. This is despite these ions gyrating on scales up to several hundred Pluto radii. To contextualize these observations, we incorporate the electromagnetic fields from a hybrid model into a novel tracing tool for energetic He+ ${\mathrm{e}}^{+}$ and generate synthetic time series of their flux into the detector along the NH trajectory and several hypothetical, idealized flyby geometries. Our major results are: (a) The detectability of perturbations to He+ ${\mathrm{e}}^{+}$ fluxes highly depends on PEPSSI's look direction. Even along the same flyby trajectory, different viewing geometries may reveal changes in helium flux by up to a factor of five or no perturbations whatsoever. (b) The substantial reductions in He+ ${\mathrm{e}}^{+}$ flux seen by NH may largely stem from the detector's finite field‐of‐view, filtering the incoming particles in velocity space. Without this effect, the reduction in flux by the draped fields would not exceed a factor of two. (c) The modeled flux perturbations gradually decrease with energy and become indiscernible above 20 keV. This behavior is qualitatively consistent with energetic ion dynamics at other small solar system bodies. (d) Across the range of plausible interplanetary field orientations, the model persistently suggests weaker reductions in He+ ${\mathrm{e}}^{+}$ flux than observed. Key Points: We model the detectability of energetic heliospheric helium ions by Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) during New Horizons' flyby through Pluto's induced magnetosphereThe observability of substantial reductions in helium ion flux within the interaction region strongly depends on PEPSSI's viewing geometryThe perturbations to the modeled helium ion fluxes into the PEPSSI detector gradually decrease with energy, in contrast to the observed ones [ABSTRACT FROM AUTHOR]
Copyright of Journal of Geophysical Research. Space Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: GreenFILE
Description
Abstract:We investigate the detectability of heliospheric helium ions at energies up to 100 keV by the New Horizons (NH) spacecraft during its flyby through Pluto's induced magnetosphere. The Pluto Energetic Particle Spectrometer Science Investigation energetic ion detector observed a reduction in their flux by an order of magnitude as the spacecraft passed through the non‐uniform electromagnetic fields near the dwarf planet. This is despite these ions gyrating on scales up to several hundred Pluto radii. To contextualize these observations, we incorporate the electromagnetic fields from a hybrid model into a novel tracing tool for energetic He+ ${\mathrm{e}}^{+}$ and generate synthetic time series of their flux into the detector along the NH trajectory and several hypothetical, idealized flyby geometries. Our major results are: (a) The detectability of perturbations to He+ ${\mathrm{e}}^{+}$ fluxes highly depends on PEPSSI's look direction. Even along the same flyby trajectory, different viewing geometries may reveal changes in helium flux by up to a factor of five or no perturbations whatsoever. (b) The substantial reductions in He+ ${\mathrm{e}}^{+}$ flux seen by NH may largely stem from the detector's finite field‐of‐view, filtering the incoming particles in velocity space. Without this effect, the reduction in flux by the draped fields would not exceed a factor of two. (c) The modeled flux perturbations gradually decrease with energy and become indiscernible above 20 keV. This behavior is qualitatively consistent with energetic ion dynamics at other small solar system bodies. (d) Across the range of plausible interplanetary field orientations, the model persistently suggests weaker reductions in He+ ${\mathrm{e}}^{+}$ flux than observed. Key Points: We model the detectability of energetic heliospheric helium ions by Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) during New Horizons' flyby through Pluto's induced magnetosphereThe observability of substantial reductions in helium ion flux within the interaction region strongly depends on PEPSSI's viewing geometryThe perturbations to the modeled helium ion fluxes into the PEPSSI detector gradually decrease with energy, in contrast to the observed ones [ABSTRACT FROM AUTHOR]
ISSN:21699380
DOI:10.1029/2026JA035261