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Stratigraphy and evolution of the buried CO 2 deposit in the Martian south polar cap
Author(s) -
Bierson C. J.,
Phillips R. J.,
Smith I. B.,
Wood S. E.,
Putzig N. E.,
Nunes D.,
Byrne S.
Publication year - 2016
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 - 10.1002/2016gl068457
Subject(s) - geology , martian , mars exploration program , polar , orbiter , astrobiology , atmosphere of mars , atmosphere (unit) , atmospheric sciences , meteorology , physics , astronomy , engineering , aerospace engineering
Observations by the Shallow Radar instrument on Mars Reconnaissance Orbiter reveal several deposits of buried CO 2 ice within the south polar layered deposits. Here we present mapping that demonstrates this unit is 18% larger than previously estimated, containing enough mass to double the atmospheric pressure on Mars if sublimated. We find three distinct subunits of CO 2 ice, each capped by a thin (10–60 m) bounding layer (BL). Multiple lines of evidence suggest that each BL is dominated by water ice. We model the history of CO 2 accumulation at the poles based on obliquity and insolation variability during the last 1 Myr assuming a total mass budget consisting of the current atmosphere and the sequestered ice. Our model predicts that CO 2 ice has accumulated over large areas several times during that period, in agreement with the radar findings of multiple periods of accumulation.