Mariner 10 ultraviolet spectrometer - Occultation experiment

A description is given of the spectrometer which was included in the scientific payload of the Mariner 10 spacecraft to measure the extinction properties of the Mercurian atmosphere at extreme ultraviolet wavelengths. The solar intensity was monitored continuously by a grazing incidence pinhole spectrometer in 150 A bands centered at 485, 740, 810 and 895 A. This instrument provided the capability of determining atmospheric surface pressures greater than one-billionth of a millibar.