Nimbus was a research program conducted by NASA in the 1960s and 1970s to study the Earth's atmosphere and weather via satellites in polar orbit. This artifact, a protype of SIRS-B (Satellite Infrared Spectrometer), is representative of a key research instrument, called a sounder, used to measure temperature and water vapor at different levels in the atmosphere.
A SIRS-B sounder flew on Nimbus 4, launched in 1970. It provided daily measurements of temperature and moisture, which then were used to develop computer models of the dynamics of the Earth's atmosphere.
This artifact is an engineering prototype and was transferred to the Museum by the National Oceanic and Atmospheric Administration in 1987.