Compositional Constraints on the North Polar Cap of Mars from Gravity and Topography

Abstract The polar ice caps are the largest reservoir of water ice on Mars. The north polar ice cap is composed of the ice‐rich north polar layered deposit (NPLD) and a lower‐lying, silicate‐rich basal unit (BU). Together, these units represent a record of Martian climate history throughout the Amaz...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Lujendra Ojha, Stefano Nerozzi, Kevin Lewis
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2019
Subjects:
Mars
poles
ice
gravity
Geophysics. Cosmic physics
QC801-809
Ice cap
North Pole
Online Access:https://doi.org/10.1029/2019GL082294
https://doaj.org/article/633c1e13ebc74feaaa69006834fdf661
Description
Summary:Abstract The polar ice caps are the largest reservoir of water ice on Mars. The north polar ice cap is composed of the ice‐rich north polar layered deposit (NPLD) and a lower‐lying, silicate‐rich basal unit (BU). Together, these units represent a record of Martian climate history throughout the Amazonian period. Here we place a bulk compositional constraint on the BU by modeling its gravity signature in both spatial and spectral domains using two independent approaches. We find the density of the BU to be 2007+493−445 kg/m3, suggesting that it may contain 55 + 25% water ice. We estimate that the BU contains ~1.5‐m global equivalent layer of water making it one of the largest reservoir of water‐ice on Mars. Our compositional constraint suggests that the north pole of Mars was not only a cold trap for ices but also an aeolian trap for silicates during the Amazonian period.

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