A Side of Mercury Not Seen By Mariner 10

TL;DR

This study presents high-resolution images of Mercury's unobserved regions, revealing detailed surface features and albedo variations linked to topography and space weathering effects.

Contribution

The paper provides new ground-based optical imagery of Mercury's surface, covering areas not seen by Mariner 10, with detailed analysis of surface features and albedo variations.

Findings

Resolved features like crater Mozart and fresh rayed craters.

Identified bright and dark surface features related to topography.

Suggested space weathering influences on surface brightness.

Abstract

More than 60,000 images of Mercury were taken at ~29 deg elevation during two sunrises, at 820 nm, and through a 1.35 m diameter off-axis aperture on the SOAR telescope. The sharpest resolve 0.2" (140 km) and cover 190-300 deg longitude -- a swath unseen by the Mariner 10 spacecraft -- at complementary phase angles to previous ground-based optical imagery. Our view is comparable to that of the Moon through weak binoculars. Evident are the large crater Mozart shadowed on the terminator, fresh rayed craters, and other albedo features keyed to topography and radar reflectivity, including the putative huge ``Basin S'' on the limb. Classical bright feature Liguria resolves across the northwest boundary of the Caloris basin into a bright splotch centered on a sharp, 20 km diameter radar crater, and is the brightest feature within a prominent darker ``cap'' (Hermean feature Solitudo Phoenicis) that covers the northern hemisphere between longitudes 140-250 deg. The cap may result from space weathering that darkens via a magnetically enhanced flux of the solar wind, or that reddens low latitudes via high solar insolation.