Widespread Excess Ice in Arcadia Planitia, Mars

TL;DR

This study reveals a widespread, decameter-thick layer of excess water ice in Arcadia Planitia, Mars, with significant implications for understanding Martian climate history and ice deposition processes.

Contribution

The paper combines crater terrace analysis and radar data to estimate the volume and distribution of excess subsurface ice on Mars, providing new insights into Martian ice deposits.

Findings

Widespread excess ice layer approximately decameters thick

Estimated volume of excess ice around 10^4 km^3

Results challenge current Martian climate models

Abstract

The distribution of subsurface water ice on Mars is a key constraint on past climate, while the volumetric concentration of buried ice (pore-filling versus excess) provides information about the process that led to its deposition. We investigate the subsurface of Arcadia Planitia by measuring the depth of terraces in simple impact craters and mapping a widespread subsurface reflection in radar sounding data. Assuming that the contrast in material strengths responsible for the terracing is the same dielectric interface that causes the radar reflection, we can combine these data to estimate the dielectric constant of the overlying material. We compare these results to a three-component dielectric mixing model to constrain composition. Our results indicate a widespread, decameters-thick layer that is excess water ice ~10^4 km^3 in volume. The accumulation and long-term preservation of this ice is a challenge for current Martian climate models.