The light-colored circular feature in the center of the scene was developed as a potential site for the testing of atomic weapons during World War II. This site is located north of Las Cruces, New Mexico, between the Rio Grande rift zone to the west and the San Andreas Mountains to the east. In this westward-oriented view, part of the San Andreas Mountains can be seen in the bottom of the frame. The weapons test site seems to be composed of two circles with diameters of approximately 1.6 and 3.2 kilometers respectively. Testing of the first atomic bomb developed by the secret Manhattan Project occurred approximately 96 kilometers north of this site in July 1945. Beginning in 1946, the U.S. nuclear testing program shifted to the Pacific Proving Ground in the Marshall Islands. In 1951 the Nevada Proving Ground (later renamed the Nevada Test Site) opened northwest of Las Vegas, Nevada, where testing continued for four decades.
March 1994, image STS-62-94-75.