The Active Cavity Radiometer Irradiance Monitor Satellite, or ACRIMSAT is a dedicated satellite and instrument that was one of the 21 primary observational components of NASA's Earth Observing System program. ACRIMSAT was launched on 20 December 1999 from Vandenberg Air Force Base as the secondary payload on a Taurus rocket along with KOMPSAT. It was placed into a high inclination, 700 km. sun-synchronous orbit from which the ACRIM3 instrument monitored total solar irradiance (TSI). Contact with the satellite was lost on 14 December 2013.