Compact Reconnaissance Imaging Spectrometer for Mars observations of northern Martian latitudes in summer

Abstract

[1] This paper brings together initial results obtained of the high northern latitudes in Mars years 28 and 29, between October 2006 and October 2008. These measurements confirm many previous models and shed new light on the nature of polar surface materials, particularly in intermediate-albedo units of the polar layered deposits, many of which are found to be ice-rich. We identify hydrated non ice materials present in many lowalbedo troughs, as well as in the circumpolar erg that was previously associated with gypsum. We identify icy outlier deposits that may be related to subsurface thermophysical properties and permafrost. New observations of the gypsum-rich dune material constrain models for its formation and distribution. Intrinsic properties of ice content and grain size are found to be independent of the albedo of fine layered units and may provide a novel method for stratigraphic identification and correlation.

MARCI and MOC observations of the atmosphere and surface cap in the north polar region of Mars

“…The composition of the RNPC of Mars is a mixture of dust and water ice (Kieffer et al, 1976;Langevin et al, 2005a;Calvin et al, 2009). The physical state of the material in the cap is characterized mainly by the grain size (more correctly the photon mean free path) of the water ice and the amount of dust contamination.…”

Recent developments in planetary Aeolian studies and their terrestrial analogs

“…Spectral analysis of strata visible in the Basal Unit and the Upper Layered Deposits (ULDs), exposed in troughs eroded through the polar ice cap, have provided support for this hypothesis. Further, the work identifies the gypsum source in the sediment-rich layers beneath and within the polar cap (Calvin et al, 2009;Massé et al, 2010Massé et al, , 2012. Massé et al (2012) suggest that the gypsum-rich sediment is ablated from the icy strata at arcuate scarps in the polar cap and from the exposed surface of Planum Boreum which underlies the Olympia Undae.…”

“…A spectral analysis of the composition of individual dunes in Olympia Undae indicate that the gypsum concentration is strongest at the dune crests, lower along the flanks and weakest in the inter-dunes (Calvin et al, 2009). At the dunefield scale, the strongest gypsum signatures are found in the closely spaced dunes of Olympiae Undae, Abalos Undae and Hyperborea Undae, located close to their proposed sediment sources (Masse et al, 2012).…”

“…Recent mapping efforts using Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) and Compact Reconnaissance Imaging Spectrometer (CRISM) data show that hydrated minerals are concentrated in the large dark dunes of the circumpolar and adjacent dunefields, as well as in the dust deposited from out of the atmosphere that veneers the surface of the polar cap (Calvin et al, 2009;Horgan et al, 2009;Massé et al, 2010Massé et al, , 2012.…”

Bedform migration on Mars: Current results and future plans

“…There are probably several reasons for this: -First, because of katabatic winds from the high elevation, cold north polar cap, the fluid, and certainly the impact, threshold speed is likely exceeded much more frequently than in most other areas of Mars (unfortunately, the Ames and other GCMs do not extend to these latitudes and modeling of wind shear stresses in the erg has not yet been done). -Second, dune migration pathways in the erg have been traced to the basal unit beneath the north polar layered deposits (Edgett et al, 2003;Fishbaugh and Head, 2005;Calvin et al, 2009;Massé et al, 2012), itself likely an ancient sand sea subsequently covered by ice. This indicates fresh sand that has not had sufficient time to become indurated, instead being continuously mobilized and transported by the winds.…”