PANTHER – First experimental demonstration of using Jovian radio bursts as an illuminator of opportunity for passive radar echo detection

The use of astronomical radio sources has been demonstrated for sounding and echo detection using quiescent solar emissions in VHF (300 MHz). Here, we present the first demonstration of using Jovian HF radio bursts (25 MHz) to detect a reflection off the hills of Dante’s View in Death Valley, California.

Solar emissions are governed by blackbody radiation, which at HF is not resolvable from the galactic background noise. In contrast, Jovian bursts are governed by the interaction of Jupiter’s magnetosphere and Io’s magnetic field, which produces a significantly stronger and detectable HF emission on Earth, Mars, and Europa. While this mechanism is not continuous, it is highly predictable, as the orbital parameters of Jupiter System III central meridian longitude and Io’s orbital phase dictate the probability of a burst occurring.

As part of the Passive Autonomy, Navigation, Topography, and Habitability Exploration Radar (PANTHER), our system setup uses an HF dipole antenna and software-defined radio (Ettus X310 TwinRX) to receive radio signals at a 25 MHz center frequency with a 20 MHz bandwidth. The expectation of the experiment was to observe the reflection of a Jovian burst from Badwater Basin, which behaves like a flat specular reflector. However, during the field demonstration, the timing of the bursts—combined with Jupiter’s elevation angle and viewing geometry from Dante’s View—did not produce a basin reflection. Instead, this experiment required a more complex geometric analysis and signal processing to determine a reflection point on the hillside of Dante’s View. We emphasize that demonstrations using Jovian bursts thus require additional geometric and timing constraints that were not required for prior passive sounding experiments using continuous quiescent solar emissions. In addition to predicting the burst windows, this technique requires selecting an antenna location that provides favorable reflection geometry.

Our results provide the first demonstration of a Jovian radio burst as an HF source for passive radar echo detection, which is the first step towards a low-resource passive HF system that uses Jovian bursts for future planetary sounding missions. Building on this first demonstration, PANTHER aims to utilize the benefits of the HF signal and its lower attenuation coefficient to sound geologic targets in Iceland including glaciers, lava flow fields, and subsurface ice deposits.