High Quality Content by WIKIPEDIA articles! Two Wide-Angle Imaging Neutral-Atom Spectrometers (TWINS) are a pair of NASA instruments aboard two United States National Reconnaissance Office satellites in Molniya orbits. TWINS was designed to provide stereo images of the Earth`s ring current. The first instrument, TWINS-1, was launched aboard USA-184 on 28 June 2006. TWINS-2 followed aboard USA-200 on March 13, 2008.