USA 420, also known as Starshield 3-21, is a satellite identified by NORAD CAT ID 61041 and OBJECT ID 2024-160W. It was launched on September 6, 2024, from AFWTR Launch Site at SLC4E using a Falcon 9 launch vehicle. The satellite has dimensions of 0.3 meters in length, a diameter of 4.1 meters, and a span of 29 meters. Its dry mass is 700 kilograms with an overall launch mass of 750 kilograms. The payload is powered by deployable solar arrays, and its configuration is based on the Starshield bus. It was manufactured by SPXS and operated by NROC for unknown purposes (possibly imaging or SIGINT). The satellite's shape is described as a box with a pan, though detailed information about its motor, ADCS, RCS, transmitter frequencies, major events, material composition, constellation name, related satellites, and sources are not available.