Difference between revisions of "March 20, 2010"
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<em>LROC Observation M104476560L from [http://wms.lroc.asu.edu/lroc#damoon LROC WMS Image Map] (illumination from the left)</em><br /> | <em>LROC Observation M104476560L from [http://wms.lroc.asu.edu/lroc#damoon LROC WMS Image Map] (illumination from the left)</em><br /> | ||
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| − | The peculiar depression [http://the-moon.wikispaces.com/Ina Ina] has a bizarre floor of [ | + | The peculiar depression [http://the-moon.wikispaces.com/Ina Ina] has a bizarre floor of [[February_3,_2010|rubbly hills and islands of smooth terrain]]. Sorting through the LRO images released on March 15 I found this image of part of the floor of Hyginus crater that looks similar. The largest roughly circular feature is 350-400 m wide, but it is not clear what the feature is. Smaller circular to irregular depressions are across the scene. The arcuate depression on the left looks like it continues as a circular feature covered by the darker material. But if Hyginus is like Ina, the dark smooth material is as old as maria outside Hyginus, suggesting that it is not a younger deposit. Thus, it seems that something is removing the terrain under the original mare surface. Like Ina, Hyginus is thought to be a volcanic collapse depression. Perhaps volcanic gases dissolve the regolith in volcanic craters causing this characteristic pattern. But what gas would do this? Comparison with the 43 year old Orbiter V [http://www.lpi.usra.edu/resources/lunarorbiter/frame/?5095 image] reveals no obvious changes so the process does not appear to be active on a human timescale.<br /> |
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<em>[mailto:tychocrater@yahoo.com Chuck Wood]</em><br /> | <em>[mailto:tychocrater@yahoo.com Chuck Wood]</em><br /> | ||
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| − | < | + | <p><b>Yesterday's LPOD:</b> [[March 19, 2010|The Case of the Missing Rim]] </p> |
| − | < | + | <p><b>Tomorrow's LPOD:</b> [[March 21, 2010|How Thick Are Rays?]] </p> |
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Revision as of 10:18, 7 February 2015
Another Ina?
LROC Observation M104476560L from LROC WMS Image Map (illumination from the left)
The peculiar depression Ina has a bizarre floor of rubbly hills and islands of smooth terrain. Sorting through the LRO images released on March 15 I found this image of part of the floor of Hyginus crater that looks similar. The largest roughly circular feature is 350-400 m wide, but it is not clear what the feature is. Smaller circular to irregular depressions are across the scene. The arcuate depression on the left looks like it continues as a circular feature covered by the darker material. But if Hyginus is like Ina, the dark smooth material is as old as maria outside Hyginus, suggesting that it is not a younger deposit. Thus, it seems that something is removing the terrain under the original mare surface. Like Ina, Hyginus is thought to be a volcanic collapse depression. Perhaps volcanic gases dissolve the regolith in volcanic craters causing this characteristic pattern. But what gas would do this? Comparison with the 43 year old Orbiter V image reveals no obvious changes so the process does not appear to be active on a human timescale.
Chuck Wood
Related Links
Rükl plate 34
Note that Pete Schultz and colleagues included Hyginus as an Ina-like object in their 2006 paper.
Yesterday's LPOD: The Case of the Missing Rim
Tomorrow's LPOD: How Thick Are Rays?
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