17 May 2019
The sol 2408 plan ended with the rover using its front wheel to dig a small trench in a ripple at the ripple field named ‘Rigg.’ That means today’s plan is focused on studying what that scuff uncovered. There is a lot that we can learn from these patches of active sand that we occasionally encounter as we explore Gale crater!
One of the big questions is where the sand comes from: by measuring the chemical composition of the sand at Rigg we can compare with sand we have seen earlier in the mission to see if the chemistry is different enough that there must be different sources. We also can compare the grain sizes in different parts of the ripple to get a better understanding of how the wind sorts sand grains under martian gravity and atmospheric pressure.
Studying the shape of the ripples in detail also helps us compare modern bedforms (the generic term for dune-like features of all sizes) to the ancient ones we see preserved in the rocks, which lets us infer similarities or differences in the environment. And of course, looking closely at these wind-blown sand features lets us get a better handle on what the winds are like in Gale crater right now.
The sol 2409 plan starts off with a Mastcam multispectral observation of the scuff, followed by ChemCam of the floor (‘Ben Cruachan’) and wall (‘Ben Lomond’) of the scuff, as well as the undisturbed crest of the ripple (‘Ben Suardal’). We’ll then use Navcam to look for dust devils before starting contact science.
Our contact science observations start with MAHLI images of targets on the ripple crest (‘Dunoon’), trough (‘Gairsay’), and a secondary ripple (‘Nairn’). APXS will then quickly measure the chemistry of Dunoon before settling in for an overnight measurement of Gairsay. We plan to keep playing in the sand at Rigg for another couple of sols before moving on toward a blocky outcrop to the northeast.
Written by Ryan Anderson, Planetary Geologist at USGS Astrogeology Science Center