Passive bistatic radar probes of the subsurface on airless bodies using high energy cosmic rays via the Askaryan effect

TL;DR

This paper introduces a passive subsurface radar technique for airless planetary bodies using radio impulses from cosmic ray impacts, leveraging the Askaryan effect to detect subsurface features without surface clutter interference.

Contribution

The paper proposes a novel passive radar method based on the Askaryan effect, enabling subsurface exploration from orbit or landers without surface clutter issues.

Findings

Simulations confirm detectable signals for planetary applications.

Technique bypasses surface clutter and backscatter.

Potential for orbiting and lander-based planetary radar.

Abstract

We present a new technique to perform passive bistatic subsurface radar probes on airless planetary bodies. This technique uses the naturally occurring radio impulses generated when high-energy cosmic rays impact the body's surface. As in traditional radar sounding, the downward-beamed radio emission from each individual cosmic ray impact will reflect off subsurface dielectric contrasts and propagate back up to the surface to be detected. We refer to this technique as Askaryan radar after the fundamental physics process, the Askaryan effect, that produces this radio emission. This technique can be performed from an orbiting satellite, or from a surface lander, but since the radio emission is generated beneath the surface, an Askaryan radar can completely bypass the effects of surface clutter and backscatter typically associated with surface-penetrating radar. We present the background theory of Askaryan subsurface radar and show results from both finite-difference time-domain (FDTD) and Monte Carlo simulations that confirm that this technique is a promising planetary radar sounding method, producing detectable signals for realistic planetary science applications.