On September 15, 1990, the Magellan spacecraft started radar operations for its mapping mission at Venus. This image is taken from the first set of radar data collected in the normal operating mode. This Magellan radar image is of part of the Danu Montes in the Lakshmi Region of Venus. The mosaic is part of orbits 376, 377, and 378 acquired on the first day of nominal mapping, September 15, 1990. Time image is located at 329.6 degrees E longitude and 58.75 degrees N latitude. This image is 40 kilometers (19.6 miles) wide and 60 kilometers (39.2 miles) high. Danu Montes is a mountain belt located at the southern edge of the Ishtar Terra highland region. It rises one to three kilometers above a flat plain to the north known as Lakshmi Planum. Lakshmi Planum contains several large volcanoes and abundant plains of volcanic origin. To the south of Danu Montes is a scarp (Vesta Rupes) marking the southern edge of Western Ishtar Terra. At the scarp the topography descends about two kilometers to the surrounding lowlands. On the basis of Pioneer Venus, Arecibo, and Venera data, Danu Montes and the other mountain belts surrounding Lakshmi Planum have been interpreted to be orogenic belts marking the focus of compressional deformation, much like the Appalachians and Andes on Earth. In the upper right part of this image, relatively bright, smooth-textured plains of Lakshmi Planum are seen to embay the heavily deformed mountain region to the south. In the mountain range south of these plains the geology is dominated by abundant faults at multiple angles and showing various cross-cutting relationships. In the northern part of the mountain the surface is dominated by sinuous, west-northwest trending troughs less than a kilometer (0.6 miles) in width, separated by narrow, flat regions. Further south are flat-floored features similar to extensional graben on Earth. These graben are up to 2 kilometers (1.3 miles) in width. The prominent bright and dark feature trending across the bottom part of the image is a linear trough about 5 kilometers wide (3.1 miles) located near the crest of the mountain range. South of the mountain crest, additional deformation is seen trending both parallel and perpendicular to the structures in other parts of the mountain belt. These patterns represent the complex tectonic deformation involved in the formation of the mountain ranges, and the graben-like features may represent extension associated with the gravitational collapse of the mountains subsequent to their initial formation.
