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

Lujendra Ojha, Stefano Nerozzi, Kevin Lewis

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


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 ~1.5-m 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.

Original languageEnglish (US)
Pages (from-to)8671-8679
Number of pages9
JournalGeophysical Research Letters
Issue number15
StatePublished - Aug 16 2019

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)


  • Mars
  • gravity
  • ice
  • poles


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