Mariner 9 michelson interferometer.

The Michelson interferometer on Mariner 9 measures the thermal emission spectrum of Mars between 200 cm(-1) and 2000 cm(-1) (between 5 microm and 50 microm) with a spectral resolution of 2.4 cm(-1) in the apodized mode. A noise equivalent radiance of 0.5 x 10(-7) W cm(-2) sr(-1)/cm(-1) is deduced from data recorded in orbit around Mars. The Mariner interferometer deviates in design from the Nimbus 3 and 4 interferometers in several areas, notably, by a cesium iodide beam splitter and certain aspects of the digital information processing. Special attention has been given to the problem of external vibration. The instrument performance is demonstrated by calibration data and samples of Mars spectra.