Comparative neutral composition instrumentation and new results

The atmospheres associated with a number of planets and moons have been studied by remote sensing. Direct in-situ measurements have been possible for the earth, moon, Mars, and Venus. Both remote sensing and in-situ instruments are under development for missions to Halley's Comet and Jupiter. Brief descriptions are provided of the more recently employed mass spectrometer systems used in missions to Venus, Mars, and Jupiter. Upper atmosphere instruments are discussed, taking into account the Pioneer Venus Orbiter Neutral Mass Spectrometer, Dynamics Explorer-B Wind and Temperature Spectrometer, and the Pioneer Venus Bus Neutral Mass Spectrometer. Lower atmospshere instruments are also considered, giving attention to a double focusing mass spectrometer of the Nier-Johnson design used in the Viking Lander, Venera instruments, the Pioneer Venus Large Probe Mass spectrometer, and the Galileo Probe Mass Spectrometer.