November 8, 2013
images from ASU/NASA and animated gif from http://gifmaker.me
Some months ago the Lunar Reconnaissance Orbiter Camera team created an LROC Featured Sites page that presented a dozen or so images under different illumination conditions for each Apollo landing site. Now they have significantly augmented that page with similar collections of images for the Surveyor, Luna, and Lunokhod landing sites, as well as the Apollo S-IVB, Ranger, and GRAIL impact sites. The Apollo 15 S-IVB pair featured here shows how different a scene can appear under only slightly different illuminations. Both are relatively high Sun views but the one completely lacking shadows shows a typical fresh crater ray pattern with bright rays radiating out from the impact site. The somewhat lower Sun image shows a different view with two of the previous bright rays extending to the left now being zones of darkness, a third dark ray zone extends out of this view to the bottom right. The difference in these incidence angles is only about one degree. This is a warning to me to not assume from looking at a single high Sun image that I understand the ejecta pattern.
Note: The S-IVBs (or S-4Bs) were the third stages of the Apollo Saturn V launch vehicles.
Yesterday's LPOD: Silly Big Image, Silly Diverse Rilles
Tomorrow's LPOD: A Luminous Bull in a Celestial China Cabinet