Active VLF transmission experiments between the DSX and VPM spacecraft Journal Article uri icon

Overview

abstract

  • This study presents results from magnetic field line conjunctions; between the medium-Earth orbiting Demonstration and Science Experiments; (DSX) satellite and the low-Earth orbiting VLF Propagation Mapper (VPM); satellite. DSX transmitted at very low frequencies (VLF) towards VPM,; which was equipped with a single-axis dipole electric field antenna,; when the two spacecraft passed near the same magnetic field line. VPM; did not observe DSX signals in any of the 27 attempted conjunction; experiments; the goal of this study, therefore, is to explain why DSX; signals were not received. Explanations include i) the predicted power; at LEO from DSX transmissions was too low for VPM to observe; ii) VPM’s; trajectory missed the “spot” of highest intensity due to the focused; ray paths reaching LEO; or iii) rays mirrored before reaching VPM.; Different combinations of these explanations are found. We present; ray-tracing analysis for each conjunction event to predict the; distribution of power and wave normal angles in the vicinity of VPM at; LEO altitudes. We find that, for low-frequency (below 4kHz); transmissions, nearly all rays mirror before reaching LEO, resulting in; low amplitudes at LEO. For mid- and high-frequency transmissions; (~8kHz and 28kHz respectively), the power at LEO is; above the noise threshold of the VPM receiver (between 0.5µV/m and; 1µV/m). We conclude that the antenna efficiency and plasmasphere model; are critical in determining the predicted power at LEO, and are also the; two most significant sources of uncertainty that could explain the; apparent discrepancy between predicted amplitudes and VPM observations.

publication date

  • November 4, 2021

has restriction

  • hybrid

Date in CU Experts

  • November 9, 2021 2:42 AM

Full Author List

  • Reid RA; Marshall RA; Starks MJ; Usanova ME; Wilson GR; Johnston WR; Sanchez JC; Su Y-J; Ginet GP; Song P

author count

  • 11

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