Curiosity, that hard-working field geologist, just keeps on delivering - this is surely the selfie to end all selfies (please). The rover continues to bustle around the Bagnold dunes, sending back extraordinary images, taking samples and sieving (Ralph Bagnold would appreciate that activity). Take a look at this screenshot from an incredible 360° interactive video:
The laws of physics - and The Physics of Blown Sand and Desert Dunes - are the same everywhere. This beautiful image of the avalanching slip-face of the "Namib dune" (the glorious full resolution can be enjoyed here) could be from a desert anywhere:
The detail and the dynamics are stunning, avalanches and sand sculpture more than 70 million kilometres away:
The sieving that Curiosity has been doing delivers the smaller than 150 micron fraction to the on-board instruments for analysis and simply dumps the larger grains.
Curiosity then gets out its hand lens and takes a close look:
From the NASA description of this image:
The larger-grain portion dumped onto the ground became accessible to investigation by other instruments on Curiosity, including imaging by MAHLI and composition analysis by the Chemistry and Camera (ChemCam) and Alpha Particle X-ray Spectrometer instruments. Laser-zapping of the dump pile by ChemCam caused an elongated dimple visible near the center of this view.
The MAHLI images combined into this focus-merged view were taken on Jan. 22, 2016, after dark on the 1,230th Martian day, or sol, of Curiosity's work on Mars. The illumination source is two white-light LEDs (light-emitting diodes) on MAHLI. They shone down on the right side of the image, so shadows are toward the left. The focus-merge product was generated by the instrument autonomously combining in-focus portions of eight separate images taken at different focus settings.
The dark appearance is purposeful: The camera team chose an exposure setting that would prevent most of the white grains in this otherwise very dark sand from being over-exposed.
Perhaps it's just a sign of being of a certain age, but all this fills me with indescribable wonder.