INVESTIGATING SOIL SURFACE CRUSTS AT JEZERO CRATER, MARS

Soils and rocks on both Earth and Mars provide a record of the past surface history, including interactions with volatiles such as water. The surfaces of Martian soils also represent the material that would be important to interactions with future human explorers. An investigation of the altered surfaces of rocks and soils on Mars is therefore critical to understanding both the past and future of that planet.

Here we present data from the Mars 2020 Perseverance rover examining the soil surface at Jezero crater, focusing particularly on investigating potential indurated crusts. MastCam-Z and Engineering cameras record surface crusts that fracture when they are disturbed by the rover wheels and by sample collection. MastCam-Z also indicates that the crust is spectrally brighter, likely indicating additional dust, but otherwise similar to the underlying soil. SuperCam Laser Induced Breakdown Spectroscopy (LIBS) measurements of soil chemistry indicate strong correlation of H, S, and Cl in the soils, along with a weaker correlation with K. These results may indicate the presence of hydrated salts as well as shed light on volatiles at Jezero crater. Repeated SuperCam LIBS measurements that form small excavation pits into the soils show changes in H with depth that may help further understand the surface crust. Understanding the formation of these surface crusts and salts can help better understand the history of Mars, as well as the implications for future human exploration. Further work is needed to examine additional crusts and rock coatings on Mars, as well as Earth and laboratory analogs, to better understand the history of the Martian surface. In particular, planned soil/regolith sampling for return to Earth will allow a detailed examination of multiple soil-forming processes on Mars including the soil crusts.

Acknowledgements: Additional substantial contributions to this work were made by Adrian Brown, Felipe Gomez, Yulia Goreva, Lucia Mandon, Germán Martinez, Jesús Martínez-Frías, Timothy McConnochie, , Sandra Siljeström, Susanne Schroeder, Mark Sephton, Svetlana Shkolyar, Shiv K. Sharma, Andrew Steele, Alicia Vaughan, Maria-Paz Zorzano Mier, the SuperCam team, the Regolith working group and the entire Mars 2020 Science and Engineering team.