The VLF Transmitter, Narrowband Receiver, and Tuner Investigation on the DSX Spacecraft

Abstract

Background and MotivationUnderstanding, specification, and mitigation of the geomagnetically trapped radiation effects on human activity in space have been topics of intense interest since the discovery of the Van Allen belts in 1958, for example, Song et al. (2001). Concerns about damage to Earth-orbiting satellite systems and humans in space have led to studies of ways such threats may be mitigated through controlled precipitation of energetic electrons from the radiation belts (Kennel & Petschek, 1966). Loss of energetic electrons from the radiation belts is known to occur as a result of Doppler-shifted gyro-resonance interactions with in situ VLF, or physically, whistler-mode waves, examples being scattering by lightning-generated whistlers, magnetospheric activity-related whistler-triggered wave bursts, bursts of natural whistler-mode noise, and whistler-mode signals from high-power ground-based VLF communication transmitters (Abel & Thorne, 1998;Imhof et al., 1983). Here we note that the whistler mode may cover

Electron Density Specification in the Inner Magnetosphere From the Narrow Band Receiver Onboard DSX

“…The primary data set was collected from NBR, a component of the Transmitter, Narrowband receiver, and Tuner circuitry (TNT) suite (Reinisch et al., 2023). NBR is a proven low‐noise heritage analog receiver design from the Radio Plasma Imager (RPI, Reinisch et al., 2000) on the NASA IMAGE spacecraft.…”

“…Cyclotron frequencies can be determined from the magnetic field magnitudes [ f ce (kHz) = 2.7386 × 10 −2 B (nT)] measured from the Vector Fluxgate Magnetometer (VMAG) on DSX with high accuracy or obtained from modeled fields when in situ measurements are not available. In this work, passive spectrograms from the Narrow‐Band Receiver (NBR, Reinisch et al., 2023) onboard DSX are automatically inspected for f uh signatures of banded emissions to yield an accurate f pe in combination with VMAG measurements. We note that the local f ce and f pe can also be determined from local resonance measurements of active spectrograms (e.g., Figure 28 in Reinisch et al., 2023).…”

“…In this work, passive spectrograms from the Narrow‐Band Receiver (NBR, Reinisch et al., 2023) onboard DSX are automatically inspected for f uh signatures of banded emissions to yield an accurate f pe in combination with VMAG measurements. We note that the local f ce and f pe can also be determined from local resonance measurements of active spectrograms (e.g., Figure 28 in Reinisch et al., 2023). Due to limited resources and because it requires a case‐by‐case examination, the active spectrogram is not discussed here; however, the method developed from our study can be applied to extract resonance traces from the active spectrogram as well.…”

Overview of the Demonstration and Science Experiments (DSX) Mission

“…The TNT instrument was required to handle highly stressful operations given that it would perform adjustable, tuned, high‐power transmissions (Reinisch et al., 2022). Each TATU included two power units.…”

Characteristics of Boomerang Whistler‐Mode Waves Emitted From the DSX Spacecraft

“…The experience on IMAGE heavily informed the design of the VLF transmitter flown on the Air Force Research Laboratory's Demonstration and Science Experiments (DSX) spacecraft (Johnston et al., 2023). Designed to operate at antenna voltages up to 10 kV, the DSX Transmitter, Narrowband receiver, and Tuner (TNT) payload (Reinisch et al., 2022) drove a semi‐rigid 80 m tip‐to‐tip center‐fed dipole antenna and was paired with a sensitive five‐channel VLF Broad Band Receiver (BBR). The receiver was connected to the 80 m boom antenna, a 16 m semi‐rigid orthogonal dipole, and a set of three orthogonal magnetic search coils.…”