Image Reconstruction Techniques in Neutron and Gamma-Ray Spectroscopy: Improving Lunar Prospector Data

TL;DR

This paper applies pixon image reconstruction to lunar neutron and gamma-ray data, significantly enhancing spatial resolution to better understand lunar surface composition and layering.

Contribution

It introduces the use of pixon image reconstruction for planetary neutron and gamma-ray spectroscopy, demonstrating improved resolution over previous methods.

Findings

Clear differentiation of lunar surface composition variations.

Identification of anorthositic regions in Hertzsprung basin.

Detection of complex layering in lunar regolith at Orientale.

Abstract

We present improved resolution maps of the Lunar Prospector Neutron Spectrometer thermal, epithermal and fast neutron data and Gamma-Ray Spectrometer Th-line fluxes via global application of pixon image reconstruction techniques. With the use of mock data sets, we show that the pixon image reconstruction method compares favorably with other methods that have been used in planetary neutron and gamma-ray spectroscopy. The improved thermal neutron maps are able to clearly distinguish variations in composition across the lunar surface, including within the lunar basins of Hertzsprung and Schrodinger. The improvement in resolution reveals a correlation between albedo and thermal neutron flux within the craters. The consequent increase in dynamic range confirms that Hertzsprung basin contains one of the most anorthositic parts of the lunar crust, including nearly pure anorthite over a region tens of km in diameter. At Orientale, the improvement in spatial resolution of the epithermal neutron data show that there is a mismatch between measures of regolith maturity that sample the surface and those that probe the near-subsurface, which suggests a complex layering scenario.