Sols 3028-3029: Tracking Transition Composition

Curiosity is on the final approach to the base of the sulfate-bearing unit identified from orbit as a region of interest within Gale crater long before we landed. The base of the unit marks a change from the underlying clay-bearing strata (rock layers) that Curiosity has been investigating for the last two years. Clay minerals are typically associated with wetter environmental conditions and sulfate minerals with drier conditions, so the contact between the two may represent a significant change in environment. It is therefore important that we carefully document the rocks for texture, structure and composition as we transition from the clay-bearing to sulfate-bearing unit, looking for gradual or abrupt changes that may help to elucidate what happened at this boundary.

Curiosity will first unstow her arm and place the APXS on the rock target “Firbeix” for a short analysis to determine the chemistry of the representative bedrock, before taking close-up images with MAHLI. As the APXS payload uplink lead today, I am responsible for overseeing the planning of the APXS measurement. After stowing the arm, the ChemCam instrument will take a passive spectroscopic observation of the “Feiullade” bedrock target, and RMI observations of another bedrock target “Fraisse” and the basal layers of the sulfate-bearing unit ahead. We will also image the Firbeix, Feiullade and Fraisse targets with Mastcam, and look at some sand cracks and the fractured terrain ahead with Mastcam mosaics. Curiosity will then drive carefully over this blocky terrain for a planned distance of ~35 meters. After the drive has executed, a MARDI image will be taken to capture the terrain beneath the two front wheels.

The second sol of this two-sol plan is dominated by environmental observations to monitor the atmosphere including a ChemCam passive sky observation, a Mastcam basic tau pointed towards the sun, a Navcam suprahorizon movie, dust devil survey and line of sight image. Standard REMS, RAD, DAN passive and active measurements will also be acquired.

Curiosity and everyone on the MSL team would also like to welcome Tianwen-1 to Mars. Congratulations to the Chinese space agency for a successful insertion into Mars orbit. It is an exciting time for Mars missions and science.

Written by Lucy Thompson, Planetary Geologist at University of New Brunswick