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Radio Occultation Measurements of The Mars Atmosphere with Mariners 6 and 7
Author(s) -
Hogan Joseph S.,
Stewart Richard W.,
Rasool S. I.
Publication year - 1972
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs007i005p00525
Subject(s) - radio occultation , occultation , mars exploration program , atmosphere (unit) , atmospheric sciences , scale height , ionosphere , atmosphere of mars , atmospheric temperature , lapse rate , physics , environmental science , meteorology , astrophysics , astronomy , martian
An analysis of the Mariner 6 and 7 occultation data has been completed. Final profiles of temperature, pressure, and electron density have been obtained for the Mariner 6 and 7 entry and exit cases, and results are presented for both the lower atmosphere and the ionosphere. The results of a detailed analysis of the systematic and formal errors introduced at each stage of the data reduction process are also included. At all four occultation points, the lapse rate of temperature was subadiabatic up to altitudes in excess of 20 km. A pronounced temperature inversion was present above the surface at the Mariner 6 exit point. All four profiles exhibit a sharp, superadiabatic drop in temperature at high altitudes, with temperatures falling below the frost point of CO 2 . These results give a strong indication of frozen CO 2 in the middle atmosphere of Mars. The analysis for the upper atmosphere indicates peak electron populations of 1.59±0.2×10 5 cm −3 near 137 km and 1.73±0.2×10 3 cm −3 near 138 km, at the Mariner 6 and 7 entry points, respectively. The plasma scale heights above these maxima were 43±6 and 47±4 km, corresponding to average topside temperatures of 388±54 and 424±35°K, for Mariner 6 and 7 entries, respectively.