The first long term solar monitor utilizing and Electrically Self Calibrating Cavity (ESCC) sensor was the Earth Radiation Budget (ERB) experiment launched on the NOAA Nimbus 7 spacecraft in 1978. The Active Cavity Radiometer Irradiance Monitor (ACRIM) I was launched in 1980 on the Solar Maximum Mission (SMM) spacecraft and produced total irradiance data until 1989. ACRIM II was launched on the Upper Atmosphere Research Satellite (UARS) and is still flying. The ACRIM III design is based on sensor technology design used in ACRIM I and ACRIM II. Packaging advances have resulted in an ACRIM III instrument that weighs half (13 kg) what the ACRIM II instrument weighed.

Instrument Heritage or ACRIM Instruments:
ACRIM II Sensor Module ACRIM II Instrument ACR II Instrument	ACR Instrument ACR and ACRIM II