Overview of the Demonstration and Science Experiments (DSX) Mission

Abstract

The Air Force Research Laboratory's Demonstration and Science Experiments (DSX) mission investigated wave‐particle interactions and the particle and space environment in Medium Earth Orbit (MEO) from June 2019 to May 2021. Its Wave‐Particle Interactions Experiment conducted over 1,300 active high power very low frequency transmissions in the radiation belts providing observations of antenna performance and signal propagation from a controlled source. This included hundreds of transmissions while in magnetic conjunction with other satellites. The Loss Cone Imager and Space Weather Experiment suite observed electron and proton populations over a wide energy range, with several of these instruments providing pitch‐angle resolution. The Space Environmental Effects Experiment investigated effects of the MEO environment on electronics and materials. The Adaptive Controls Experiment demonstrated technology for on‐board identification and control of large structure vibrational modes. We describe the DSX instrument capabilities and on orbit performance, science planning and operations for carrying out an array of active and passive experiments, and some initial results in brief. We also describe plans for further work and data release.

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

“…The history of artificial space‐to‐space VLF radio transmission is brief for practical reasons. Until the DSX mission (Johnston et al., 2022) demonstrated that the radiation resistance of an electrically short 80‐m long antenna in the VLF whistler mode reaches the order of kilo‐Ohms (Song et al., 2022), the conventional wisdom was that active VLF antenna structures would either have to be prohibitively large for their deployment on spacecraft platforms or the antenna driving current must be extremely large. Therefore, missions into the Earth's near‐space environment more commonly carry VLF receivers to observe artificial emissions from ground‐based mega‐power transmitters whose signal leaks into the magnetosphere through the ionospheric barrier.…”

“…DSX conducted many active VLF experiments in the plasmasphere under various plasma conditions over a range of frequencies (Johnston et al., 2022; Tu et al., 2022). It confirms the impedance measured by RPI and theoretical predictions from 3 to 45 kHz.…”

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

“…All ray tracing in this study was conducted in Generation 13 of the International Geomagnetic Reference Field (IGRF) (Alken et al., 2021) using the appropriate epoch for the experiment being simulated. The DSX Vector Magnetometer instrument (Johnston et al., 2023) measured the local magnetic field at the spacecraft, which matched the IGRF fields within 0.4% in magnitude and 5° in angle across the data set used in this analysis. We note that the angular deviations may at least partially originate in the uncertainties in the DSX spacecraft clock and actual correspondence is likely better.…”

“…supplemental data in Johnston et al. (2023)), calendar date [mm/dd/yyyy], time [UT], transmit frequency f [kHz], transmit pulse length t p [ms], received echo delay t e [ms], plasma frequency derived from TNT spectrograms f pe [kHz] (“unk” if no TNT data are available), DSX L shell, DSX magnetic latitude λ m [deg], scaling factor for the Ozhogin plasmaspheric density model k Oz , and scaling factor for the Angerami and Thomas (1964) diffusive equilibrium density model (discussed later) k AT 64 . Note that the reported transmit times are estimated to be accurate to only ±10 s. Figure 5 illustrates the locations at which DSX conducted the 25 selected experiments in Table 1, along with those of 22 “no boomerangs” experiments that will be addressed in Section 4.…”

“…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).…”