May 26, 2006

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Three Rilles and a Strange Volcano

Roris Rilles
image by Paolo R. Lazzarotti and T. Olivetti

Magnificent images require breaking of rules. As Paolo Lazzorotti and T. Olivetti release their extraordinary images taken in Bangkok, I can’t help but use them two days in a row. In this case, the area shown better than ever before from Earth, is west of Terra Pruinae, that is, on the east side of Sinus Roris. The crater at bottom right is Mairan - and it is totally over processed because of my efforts to bring out the rilles; see the original image for the best terrestrial view ever of Mairan. This image has west up and shows three rilles - one quite peculiar - and a strange volcanic cone. The cone is the steep-sided, crater-topped bright hill near the top right. It used to be named Mairan T, but now seems to be undesignated. The crater is 2.4 km wide and is on top of a 6.5 km wide cone that is 900 m high. It is apparently made of lava more viscous than typical mare basalts. The rille at upper right is the Sharp Rille, which continues to the north (the right), and fades out near the middle of the image. The starting gorge of the Mairan Rille is conspicuous near the center left and it meanders, snakelike, about 90 km to the right. I wonder if the Mairan Rille might have once been continuous with the Sharp Rille. Saving the weirdest for last there is a braided looking, slightly meandering chain of pits at the bottom left. This feature is well seen in a Lunar Orbiter view but the picture doesn’t explain the origin. The pit chain seems to be associated with the distinctive curved feature on its right end. And this curved feature is similar to the starting point of other sinuous rilles. The odd chain is probably a lava tube that has collapsed partially, creating the pits. The really intriguing thing is that the south end of the chain seems to be continuous with a narrow mare ridge, almost as if the ridge is an uncollapsed part of the lava tube. Wonderful image!

Technical Details:
10 April 2006, Gladio 315 Lazzarotti telescope (f/25), Lumenera Infinity 2-1M camera, Edmund Optics G filter IR blocked, 341 frames stack out of 2000. This is just a piece of a larger image. I have strongly enhanced the image to bring out the rilles.

Related Links:
Rükl plate 9
Paolo’s website

Yesterday's LPOD: Sideways Slam

Tomorrow's LPOD: L98


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