How thick are Mercury's polar water ice deposits?

TL;DR

This study estimates the thickness of water ice deposits in Mercury's polar craters using radar data and digital elevation models, providing an upper limit on the total ice mass present.

Contribution

Developed an automated crater detection algorithm and applied it to Mercury data to estimate ice deposit thickness and total mass.

Findings

Radar-bright deposits are approximately 50 meters thick.

Estimated total polar water ice mass is up to 3 x 10^15 kg.

A new crater catalog of 663 craters was created for analysis.

Abstract

An estimate is made of the thickness of the radar-bright deposits in craters near to the north pole of Mercury. To construct an objective set of craters for this measurement, an automated crater finding algorithm is developed and applied to a digital elevation model based on data from the Mercury Laser Altimeter on board the MESSENGER spacecraft. This produces a catalogue of 663 craters with diameters exceeding 4 km, northwards of latitude +55 degrees. A subset of 12 larger, well-sampled and fresh polar craters are selected to search for correlations between topography and radar same-sense backscatter cross-section. It is found that the typical excess height associated with the radar-bright regions within these fresh polar craters is (50+/-35)m. This puts an approximate upper limit on the total polar water ice deposits on Mercury of 3e15 kg.