Curiosity Blog, Sols 4968-4974: Rock Climbing Towards the Discontinuity
Curiosity is exploring a large-scale feature in Gale's sedimentary record suspected to be an "erosional supersurface"—a period when a net depositional environment changed to a net erosional one before returning to deposition, creating a discontinuity in the rock record. Erosion could have involved wind, water, or both, and clues may be preserved in the layers above and below. So far, the rover has seen patterns suggestive of aeolian features and "lens" deposits that sometimes look consistent with fluvial origins, but higher-resolution imaging was needed.
This week, Curiosity came within detailed imaging range of a section of the "Cerro Paine Grande" vertical exposure just below the candidate supersurface, then climbed on top of it. Mastcam captured large stereo mosaics of the vertical face and a 360-degree panorama after the climb. The ascent took full advantage of Curiosity's climbing capabilities, leaving the rover at an approximate 24-degree tilt in its final parking spot—while still achieving the correct posture for contact science, approaching the mission's contact-science tilt record of 27 degrees. MAHLI and geochemical instruments provided detailed characterization of the rock layers beneath the discontinuity.
On Sol 4968, the Geology and Mineralogy Theme Lead planned co-targeting of "Puyehue" in a light-toned bedrock block with APXS, MAHLI, and ChemCam LIBS. Two additional targeted LIBS observations went to a similar nearby block ("Lago Palena") and an intriguing layered block off to the side ("Piedras Juntas"). An APXS measurement on the sand target "Cormudesi" will help assess the consistency of sand compositions along the rover's traverse.
In the Sol 4972 workspace atop the slope, the bedrock was sharply divided between a smooth bedding-parallel surface on the top and a darker-toned, rougher, angled exposure of the same rocks. The light-toned top surface was measured by MAHLI, APXS, and LIBS at "Sierra de Sangre," while the darker-toned laminated face was targeted by APXS and MAHLI at "Laguna del Laja." A MAHLI mosaic ("Longquimay") documented fine-scale sedimentary structures, supported by Mastcam M100 imaging. The week's observations also included several long-distance ChemCam RMI mosaics on more distant features.