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A strong seasonal dependence in the Martian hydrogen exosphere
Bertaux, Jean-Loup; Chaufray, Jean-Yves; Clarke, John T. +2 more
Hubble Space Telescope and Mars Express observed unexpected rapid changes in the Martian hydrogen exosphere involving a decrease in scattered Lyman α intensity in fall 2007 (solar longitude, Ls = 331°-345°). These changes detected were speculated to be a combination of seasonal variation and/or dust storms and lower atmospheric dynamics…
An ionized layer in the upper atmosphere of Mars caused by dust impacts from comet Siding Spring
Gurnett, D. A.; Persoon, A. M.; Morgan, D. D. +4 more
We report the detection of a dense ionized layer in the upper atmosphere of Mars caused by the impact of dust from comet Siding Spring. The observations were made by the ionospheric radar sounder on the Mars Express spacecraft during two low-altitude passes approximately 7 h and 14 h after closest approach of the comet to Mars. During these passes…
Ten years of Martian nitric oxide nightglow observations
Montmessin, Franck; Bertaux, Jean-Loup; Stiepen, Arnaud +2 more
We present 10 years of Martian NO nightglow Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars observations in limb and stellar occultation modes. The NO nightglow is used as a tracer of the summer-to-winter hemispherical circulation in the upper atmosphere of Mars. Its distribution roughly follows the curve latitude = -80…
The equivalent slab thickness of Mars' ionosphere: Implications for thermospheric temperature
Gurnett, D.; Mouginot, J.; Kofman, W. +4 more
The total electron content (TEC) of a planetary ionosphere is dominated by plasma near and above the height of maximum electron density (Nmax). The ratio TEC/Nmax represents the thickness (τ) of a TEC slab of uniform density (Nmax). For a photochemical ionosphere, τ relates to the scale height (H = kT/mg) of the io…