Lunar Subsurface Ice Detection with Cosmic-ray Showers

Ultra-high Energy (UHE) cosmic rays produce showers when they interact with matter, leading to a coherent radio pulse known as the Askaryan effect. The UHE neutrino experiment ANITA was able detect cosmic rays interacting in the atmosphere using radiofrequency measurements from a balloon-borne interferometer. Building off this technique, the radio pulse could in turn be used to study subsurface structures on airless planetary bodies as a bistatic radar probe. The Cosmic Ray Lunar Soundar (CoRaLS) is an experiment that plans to take advantage of this effect to study potential near surface ice deposits beneath the Moon's southern polar region. CoRaLS expects to be able to probe down to tens of meters below the surface, much deeper than what traditional radar techniques have been able to achieve due to the Moon's surface roughness.