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First FIPS spectrum of ions in Mercury's exosphere

First FIPS spectrum of ions in Mercury's exosphere
First FIPS spectrum of ions in Mercury's exosphere MESSENGER's Fast Imaging Plasma Spectrometer (FIPS) scoops up ions from Mercury's exosphere and measures their composition as a ratio of their mass to their charge. Each atomic or molecular ion shows up as a distinct peak in this spectrum. Most ions are singly charged (missing one or having one extra electron) so are visible as a peak at the atomic mass of the element (for example, sodium at 23). A few are present as multiply charged ions, for instance doubly chaged oxygen at a peak of 8. The surprising result is the detection of water-related ions like O+, OH-, and H2O+. NASA / JHUAPL / U. Michigan