USA 129, also known as Enhanced CRYSTAL 2106, is a reconnaissance satellite with an electro-optical mission launched on December 20, 1996, from AFWTR's SLC4E launch pad using the Titan 404A launch vehicle. The spacecraft has dimensions of 19 meters in length and 3.1 meters in diameter, with a span of 30 meters, and a dry mass of 10,000 kg. It was manufactured by LMMS/TRW for NROC (National Reconnaissance Office). The satellite's configuration is described as Bus-1 with deployable solar arrays and batteries for power supply. Its shape is characterized as cylindrical with two panels.