Work

Constraints on the Observability of Energetic Neutral Atoms From the Magnetosphere‐Atmosphere Interactions at Callisto and Europa

Year: 2024

Type: article

Abstract: We investigate the emission of energetic neutral atoms (ENAs) from the magnetosphere‐atmosphere interactions at Europa and Callisto that may be observed by an ENA imaging instrument. To do so, we combine the draped electromagnetic fields from the AIKEF hybrid model with a tracing tool for the energetic magnetospheric parent ions. Using a realistic viewing geometry, synthetic ENA images are generated for multiple detector positions and orientations with respect to the magnetospheric field. At both moons, we investigate the ENA emission morphology at different distances to the center of Jupiter's plasma sheet. By generating ENA images for uniform electromagnetic fields as a baseline, we also constrain the influence of field line draping and induction signals on the observable ENA emission signatures. Our major findings are: (a) In uniform fields, regions of elevated ENA flux in the images populate segments of a ring around each moon's disc. (b) The radial and angular extensions of these segments decrease with growing magnetospheric field strength. (c) The angle between the detector's boresight vector and the ambient field determines the regions of the images populated with elevated ENA flux. (d) Non‐uniformities in the fields are discernible in the ENA images only when Europa and Callisto are located near the center of Jupiter's plasma sheet. Even in this case, the visibility of such features is restricted to certain viewing geometries. (e) Anisotropies in the moons' atmospheric density profiles produce gradients in the observable ENA emissions. This facilitates a global characterization of these neutral envelopes through ENA imaging.

Source: Journal of Geophysical Research Space Physics

DOI: 10.1029/2024ja033391

Authors: C. Michael Haynes, Tyler Tippens, Sven Simon, Lucas Liuzzo

Institutions: Georgia Institute of Technology, Space Sciences Laboratory, University of California, Berkeley

Language: English

Topic: Ionosphere and magnetosphere dynamics

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,880

Funders: National Aeronautics and Space Administration, Nuclear Safety and Security Commission