ABSTRACT
The experiments to obtain meteorological data from satellites were included in the American Vanguard and Explorer satellite systems of 1959, but the first satellite designed specifically for meteorological observations was Tiros I, launched on 1 April 1960. The meteorological sensors that measure radiation in the visible waveband obviously operate over sunlit areas, whereas sensors measuring outside the visible are more tolerant of the absence of current solar illumination. The significant relationship to be optimized during the planning of a sun-seeking satellite orbit is that between the daylight terminator and the satellite track. An alternative method of maintaining constant picture orientation was demonstrated first by Tiros IX. A similar method was employed later through the entire Essa operational satellite system. The earth-orientated sensors, viewing through the satellite side walls, scan across the target area as the satellite spins in space. Most of the photographic satellites during the 1960s employed television-type cameras as their principal meteorological sensors.
