September 17, 2013
A Busy Neighborhood
southeast up image by Alex Sanz, Ayllón - Segovia -Spain
How many features can you name in this scene? Perhaps only one is unique enough and big enough to be reasonably well known (L58 in fact) - the Rheita Valley. And if that is the name of the valley then its a good chance that the central peak crater that cuts it just behind its snake-like head is Rheita. The crater Rheita must be younger than the Nectaris Basin, for the formation of that large feature included the ejection of a chain of small mountains that made the valley as a basin secondary chain. If you look down the valley towards the terminator you will see Young, a crater older than Nectaris because the valley cuts through it, apparently piling up ejecta on its floor. It would be strange that so much ejecta came from a secondary, perhaps instead it is from the 45 km wide, nearly completely shadowed Young D, that is superposed on the valley. In fact, the pile of material on the floor of Young (which just to be confusing is old) looks like a mass of ejecta from Fabricius that occupies the middle of Janssen. But the LRO QuickMap topo data shows that the pile is the bottom part of an unexpected peak on the rim of Young. Now take a look at the smooth material on the floors of some of the components of the Rheita Valley. I was going to say that that was probably fluidized ejecta from the formation of the Nectaris Basin that fell everwhere and collected in the low spots. But there is similar smooth stuff in the crater Rheita, so its floor fill can't be from Nectaris and thus perhaps that in the valley is not either. Hmm. We've no time for other unique features such as Rheita E, obviously a basin secondary chain but from which basin? or the Neander Fault, but those have had their own LPODs.
Aug 24th 2013 03:42 U.T. C11 at f30 + DMK31+ red filter; 2 piece mosaic.
21st Century Atlas charts 5 & 6.
Yesterday's LPOD: Wasted Space
Tomorrow's LPOD: Pointing To the Problem