SPS Seminar - Regolith of Jezero crater, Mars: textures, composition, and implications for provenance from the Mars 2020 Perseverance rover

When:  Thursday 20^th October at 16.00

Where:  Microsoft Teams - Online

Speaker:  Dr Emily Cardarelli (JPL)

Hosted by: Alexander Barrett

Abstract:

The Perseverance rover successfully landed in Jezero crater, Mars on February 18, 2021, at the Octavia E. Butler landing site and began its mission to explore and sample an ancient crater lake basin. A multi-instrument study of the regolith of Jezero crater floor units by the Perseverance rover has identified three types of regolith: fine-grained, coarse-grained, and mixed type over the first 350 sols. Mastcam-Z, WATSON, and SuperCam RMI were used to characterize regolith texture, grain sizes, and roundedness where possible. Mastcam-Z multispectral and SuperCam LIBS data were used to constrain the composition of the regolith types. Fine-grained regolith is found surrounding bedrock and boulders, comprising bedforms, and accumulating on top of rocks in erosional depressions. Spectral and chemical data show it is compositionally consistent with pyroxene and a ferric-oxide phase. Coarse-grained regolith consists of 1-2 mm well-sorted gray grains that are found concentrated around the base of boulders and bedrock, and armoring bedforms. Its chemistry and spectra indicate it is olivine-bearing, and spatial distribution and roundedness suggest it has been transported, likely by saltation-induced creep. Coarse grains share significant similarities with the olivine grains observed in the Séítah formation bedrock, making that unit a possible source for these grains. Mixed-type regolith contains fine- and coarse-grained regolith components and larger rock fragments. The rock fragments are texturally and spectrally similar to bedrock within the Máaz and Séítah formations thereby suggesting origins by erosion from those units, although they could also be a lag deposit from erosion of an overlying unit. The fine- and coarse-grained types are also compared to their counterparts at other landing sites to inform global, regional, and local inputs to regolith formation within Jezero crater.

BIO

NASA’s Mars 2020 Mission team member Dr. Emily Cardarelli is an astrobiologist and geomicrobiologist who holds a M.S. and Ph.D. in Earth System Science (Geomicrobiology and Biogeochemistry Tracks) from Stanford University. Her research is focused on understanding how microorganisms and planetary systems interact across spatial scales and geologic settings. Using field-based and laboratory studies, her prior work identified vertical and spatiotemporal patterns for sediment-associated microbiomes and the corresponding geochemistry in subsurface Critical Zones, wherein sediment, rock, microbial life, and water interact.

As a JPL Postdoctoral Fellow, Dr. Cardarelli is a collaborator on the SHERLOC and MastcamZ Instrument Teams and Tactical Science Lead on the Mars 2020 Science Team. She presently investigates the biosignature preservation potential of magnesium carbonates in Mars-analog environments and rock-regolith geochemical transitions in Jezero crater, in pursuit of identifying signs of ancient life and unique records of geological processes on Mars.