Geologic Map of the Nemesis Tesserae Quadrangle (V–13), Venus

The Magellan spacecraft orbited Venus from August 10, 1990, until it plunged into the Venusian atmosphere on October 12, 1994. Magellan Mission objectives included (1) improving the knowledge of the geological processes, surface properties, and geologic history of Venus by analysis of surface radar characteristics, topography, and morphology and (2) improving the knowledge of the geophysics of Venus by analysis of Venusian gravity.

The Nemesis Tesserae quadrangle (V–13) is in the northern hemisphere of Venus and extends from lat 25° to 50° N. and from long 150° to 180° E. It covers the area between Atalanta Planitia to the north, Vellamo Planitia to the west, and Llorona Planitia to the southwest. Nemesis Tesserae consists of an elongated centralized deformed lowland flooded by volcanic deposits and surrounded by the Vedma Dorsa deformation belt to the west and Nemesis and Athena Tesserae to the east. In contrast to more equidimensional lowlands (basins) such as Atalanta and Lavinia Planitiae, the area of the Nemesis Tesserae quadrangle represents the class of elongated lowland areas on Venus confined between elevated regions. The Nemesis Tesserae quadrangle is an important region for the analysis of processes of basin formation and volcanic flooding.