Launch: December 20, 1999
Mass: 115 kilograms (253 pounds)
Science instruments: Active cavity radiometer
The Active Cavity Radiometer Irradiance Monitor Satellite (AcrimSat) is designed to monitor the total amount of the Sun's energy reaching Earth. It is
this energy, called total solar irradiance, that creates the winds, heats the land and
drives ocean currents. Some scientists theorize that a significant fraction of Earth's
global warming may be solar in origin due to small increases in the Sun's total energy
output since the last century. By measuring incoming solar radiation, climatologists will
be able to improve their predictions of climate change and global warming over the next
Similar instruments were flown on the Solar Maximum satellite in the 1980s and the
Upper Atmosphere Rearch System (UARS) satellite in the 1990s. AcrimSat was launched
December 20, 1999, as a secondary payload on a Taurus rocket from California's
Vandenberg Air Force Base. AcrimSat circles Earth from a polar orbit at an altitude
of 685 kilometers (about 425 miles). The Taurus' primary payload was the Korea
Multi-Purpose Satellite, or KompSat.
The AcrimSat instrument was designed and built by JPL, which also manages the mission. The
satellite was designed and built by Orbital Sciences Corp.
For more information, see the AcrimSat home page.