Stratospheric aerosol measurement
From Glossary of Meteorology
Stratospheric Aerosol Measurement
(Abbreviated SAM.) A single channel sun photometer centered at 1 micron used to measure aerosol extinction above the earth tangent point by looking at the sun during spacecraft sunrise and sunset.
SAM was initially tested as a hand-held sun photometer on Apollo–Soyuz in 1975. A follow- on SAM-II instrument was carried onboard ''Nimbus''-7 (launched October 1978).