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First SHERLOC Results from Mars 2020’s Green Zone Campaign in Jezero Crater

Presentation #206.07 in the session “Mars: From the Surface to the Atmosphere”.

Published onOct 03, 2021
First SHERLOC Results from Mars 2020’s Green Zone Campaign in Jezero Crater

We present the first deep-ultraviolet (DUV) Raman and fluorescence spectra measured on Mars by SHERLOC onboard Mars 2020’s Perseverance rover, acquired as part of the mission’s Green Zone campaign exploring the edge of the Séítah region in Jezero crater, southwest of the Octavia E. Butler landing site. SHERLOC operates by moving a focused 100 μm diameter laser spot (excitation wavelength: 248.6 nm) between discrete points on the target surface, measuring both Raman and fluorescence simultaneously at each point. Using DUV excitation, SHERLOC measures Raman scattering from organics and minerals in a narrow wavelength range (250–273 nm) before the onset of significantly stronger organic fluorescence (274–355 nm), enabling simultaneous analysis of both phenomena. This allows SHERLOC to detect and classify organic matter and minerals across a wide range of concentrations at sub-millimeter scales. During the Green Zone campaign, we have acquired spectral maps of up to 7x7 mm (and spatial resolutions of 100–780 μm) for natural rock surfaces named Nataani (sol 83), Bi La Sana (sol 98), and Foux (sol 141). Further measurements are expected on both natural surfaces and, starting August 2021, sub-surface material down to depths of 14 mm revealed by Perseverance’s abrasion tool. These maps are co-located with context images that cover ~16.2 by ~12.1 mm at 10.1 μm/pixel, providing the first in situ, grain-scale views of the spatial distribution of organic and mineral composition of rocks on the Martian surface. The initial results reveal two spatially and spectrally distinct fluorescence signatures with maxima at 275 and 346 nm, and Raman peaks consistent with amorphous silicates. Combined with measurements by other instruments, such as PIXL, SuperCam, and MastCam-Z, these data offer invaluable geological and astrobiological context that will influence future decisions to collect and cache samples for eventual return to Earth.

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