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A rapid decrease of the hydrogen corona of Mars
Author(s) -
Clarke J. T.,
Bertaux J.L.,
Chaufray J.Y.,
Gladstone G. R.,
Quemerais E.,
Wilson J. K.,
Bhattacharyya D.
Publication year - 2014
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 - 10.1002/2014gl061803
Subject(s) - mars exploration program , astrobiology , atmosphere of mars , martian , atmosphere (unit) , atmospheric escape , planet , atmospheric sciences , hydrogen , environmental science , astronomy , physics , meteorology , quantum mechanics
Mars is believed to have lost much of its surface water 3.5 billion years ago, but the amounts that escaped into space and remain frozen in the crust today are not well known. Hydrogen atoms in the extended martian atmosphere, some of which escape the planet's gravity, can be imaged through scattered solar UV radiation. Hubble Space Telescope (HST) images of the ultraviolet H Ly α emission now indicate that the coronal H density steadily decreased by a factor of roughly 40% over 4 weeks, a far greater variation than had been expected. The leading candidate cause is a decrease in the source rate of water molecules from the lower atmosphere, consistent with seasonal changes and a recent global dust storm. This implies that the rate of escape of martian hydrogen (and thereby water) into space is strongly dependent on the lower atmospheric water content and distribution.