MISSION UPDATES | June 21, 2017

Sols 1734-1735: Gazing Longingly towards Vera Rubin Ridge

Written by Mark Salvatore, Planetary Geologist at University of Michigan

Curiosity continues to drive to the east-northeast around two small patches of dunes that are positioned just north of Vera Rubin Ridge. Once beyond this easternmost dune patch, the plan is for her to turn to the southeast and towards the location identified as the safest place for Curiosity to ascend the ridge. Currently, this ridge ascent point is approximately 370 meters away, which is less than the exterior length of Wembley Stadium in London. If only the path ahead were as smooth as a soccer pitch!

After a ~15 meter drive, Curiosity is situated in front of several small patches of rock about the size of large textbooks. This front Hazard Avoidance Camera (Hazcam) image shows today's view, with Mt. Sharp in the background and a portion of Vera Rubin Ridge in the upper-right corner. One of these rocks, a target known as "Pecks Point" exhibits some interesting variations in brightness, and so its chemistry will be analyzed using the APXS and ChemCam instruments, and it will be imaged using both MAHLI and Mastcam. The remainder of the science for this plan is focused on gazing longingly towards Vera Rubin Ridge. From this vantage point, we will be acquiring imagery of the northern exposure of the ridge (named "Northern Neck") using several techniques. First, we will use the multispectral capabilities of Mastcam (see below for more details) to investigate any possible compositional variations observed within this lower ridge material. Next, we will take a series of overlapping high-resolution images using ChemCam's remote microimager. Although these images won't cover the entirety of the exposure, they will allow scientists to interrogate the fine-scale sedimentary structures present within the ridge. Lastly, we will again turn to Mastcam to image the entirety of "Northern Neck" in true-color, similar to how your eyes would perceive the ridge if you were standing on the surface.

After this science imaging, Curiosity will again take off driving towards the east-northeast. The following day, Curiosity will image the rover deck using Mastcam, hunt for dust devils using the navigation cameras, and acquire additional chemistry data of local targets using ChemCam's automated target selection software known as AEGIS. The science and engineering teams will again reconvene on Friday to formulate the weekend's science plan.

I want to provide a little more context regarding the multispectral imaging capabilities of Mastcam. The cones in a human eye are sensitive to blue, green, and red wavelengths of light which, combined, allow us to see the full range of visible colors. Using a series of filters, Mastcam is able to finely control the wavelengths of light that enter the camera. This means that we can accurately calibrate the data to quantify how surfaces reflect specific wavelengths of light. In addition, Mastcam can record wavelengths beyond the sensitivity of the human eye in the near-infrared, and this additional information can be used to further investigate the composition of the martian surface. Just like how table salt is white and garnets are red, other geologic materials exhibit unique signatures in the infrared as well. As a result, Mastcam is an extremely useful geologic tool onboard Curiosity, as it allows us to investigate differences in the composition of distant surfaces.

One of the key compositional properties of Vera Rubin Ridge is the presence of the iron oxide phase hematite, as determined from orbital observations. Iron oxides are the primary constituents of rust on Earth, which can exhibit spectacular variations in color, and so identifying and characterizing minor color variations throughout the ridge will be important as the mission continues towards the ridge. What is the lateral and vertical distribution of these unique iron oxide phases? Do they vary significantly over the rover's traverse? These questions (and many more) will continue to be the focus of the MSL science team for months to come!