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Changes in the thermosphere and ionosphere of Mars from Viking to MAVEN
Author(s) -
Withers Paul,
Vogt Marissa,
Mahaffy Paul,
Benna Mehdi,
Elrod Meredith,
Jakosky Bruce
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl065985
Subject(s) - thermosphere , mars exploration program , ionosphere , atmospheric sciences , atmosphere of mars , atmosphere (unit) , solar minimum , environmental science , solar maximum , astrobiology , solar cycle , altitude (triangle) , physics , meteorology , solar wind , martian , geophysics , plasma , quantum mechanics , geometry , mathematics
We compare Viking and Mars Atmosphere and Volatile EvolutioN mission (MAVEN) Neutral Gas and Ion Mass Spectrometer (NGIMS) observations of the thermosphere and ionosphere of Mars in order to test predictions of large variations in conditions over the solar cycle and with season. Substantial differences exist between the Viking observations at solar minimum and near aphelion and the MAVEN NGIMS observations at moderate solar activity and near perihelion. Differences in the O/CO 2 ratio, the O + ionospheric peak, ion densities at high altitude, and neutral and ion scale heights can be attributed to differences in solar activity and season, but the relative importance of solar activity and season for these differences was not established. Current models do not explain the observed differences in the mixing ratios of N, NO, and O 2 . These results place new constraints on models of how the thermosphere and ionosphere of Mars vary over the solar cycle and with season.