Mastcam Spectral Diversity Within Glen Torridon, Gale Crater, Mars

The Mars Science Laboratory (MSL) Curiosity rover has traveled through nearly 400 vertical meters of sedimentary strata since landing in Gale crater in 2012. Its extensive traverse has generated data useful for evaluating chemical and stratigraphic relationships with implications for processes that shaped the aqueous history of Mars. Distinct stratigraphic units encountered along the traverse have been defined on the basis of outcrop morphology and chemical characteristics, as observed by Curiosity's instrument suite. This includes the Mast Camera (Mastcam), which has periodically acquired multispectral, visible to near-infrared (VNIR) observations (used to make broad distinctions between iron mineralogies, oxidation states, and hydrated phases) of outcrops in Gale crater's stratigraphic sequence.

We make traverse-wide comparisons of spectral variation within and between stratigraphic units using a newly compiled database of all multispectral observations taken in Gale crater. By analyzing multispectral observations of dusty and dust-cleared rocks while considering their broader stratigraphic context, we can identify spectral parameters characteristic of particular rock units. Spectra for in-place and float rocks of the clay-bearing Glen Torridon region Curiosity is currently exploring tend to have less prominent Fe-oxide bands (at 867 and 527 nm) than the high-hematite rock targets of the Vera Rubin Ridge, but fall within the range of Fe-oxide bands observed in the Murray Formation as a whole. Spectra of Glen Torridon drill tailings are spectrally similar to each other, as well as the Quela and Stoer drill targets encountered earlier in the rover's traverse. Rubbly and coherent sub-facies of this unit exhibit different spectral signatures, particularly in the near-IR slope. These relationships can be used to shape the exploration of Glen Torridon, and sharpen the stratigraphic model for deposition and alteration in Gale crater.