Evidence from Voyager II photometry for early resurfacing of Umbriel (original) (raw)

NASA/ADS

;

• Thomas, P. C. ;
• Veverka, J.

Abstract

THE uranian satellite UmbriePs dark, heavily cratered surface is remarkable for its apparent uniformity in Voyager II images1. Its most conspicuous geological feature is a comparatively high-albedo, annulus-shaped deposit which covers the floor of the 40-km diameter crater Wunda1. Here we present new Voyager II albedo maps of Umbriel which reveal that its surface is subdivided into low-contrast, crudely polygonal areas ranging in size from tens to hundreds of kilometres (Fig. 1). The largest polygons are elongate with systematically trending northeast-southwest boundaries. Some of the polygonal areas form topographic depressions several kilometres in depth. We suggest that this newly discovered global albedo pattern is a relic of the early tectonic disruption of Umbriel's surface.

Publication:

Nature

Pub Date:

March 1989

DOI:

10.1038/338324a0

Bibcode:

1989Natur.338..324H

Keywords:

• Astronomical Photometry;
• Satellite Surfaces;
• Umbriel;
• Voyager 2 Spacecraft;
• Albedo;
• Tectonics;
• Topography;
• Lunar and Planetary Exploration; Satellites of Uranus;
• URANUS;
• UMBRIEL;
• SATELLITES;
• VOYAGER 2 MISSION;
• SPACECRAFT OBSERVATIONS;
• PHOTOMETRY;
• RESURFACING;
• ALBEDO;
• SURFACE;
• FEATURES;
• PATTERNS;
• TECTONICS;
• IMAGERY;
• PROCEDURE;
• TECHNIQUES;
• BRIGHTNESS;
• PARAMETERS;
• TOPOGRAPHY;
• STRATIGRAPHY