i helped plan a mahli observation on monday! showed up to planning and saw some beautiful gray rocks in front of the rover. these rocks have some very fine layers in them, only a few mm thick. the layers are what give the rock the corrugated appearance. there are a lot of small white veins cutting through this rock - not uncommon, nearly every rock exposure in gale crater is shot through with gypsum veins - but what caught my eye is that this little spot looked sort of like a "clot", a little clump of vein material. it was a complicated planning cycle read about it on the official mission blog here, but i was able to shepherd the request through! this rock received the name 'acara'
one thing the rover does is take navcam images to document the arm while it's in use. the black and white photo shows the arm while mahli was taking a photo of the acara. mahli took a slightly modifed version of its standard suite - an image from 26 cm and a stereo pair from 10 cm (we normally do about 5 cm, but due to the issues noted in the blog post we couldn't get much closer than 10 cm). even from the slightly increased range we saw some really cool textures in the vein. if you look closely you can see little tendrils of vein fill snaking out into the surrounding rock, as well as some small pieces of gray rock that look like they cracked off the vein walls. these textures will be useful to help figure out how the veins formed in the rock to begin with.