Scientists: No obvious ice in the permanently-shadowed interior of Shackleton Crater
Click for original image.
Using the low-light image produced by the American Shadowcam instrument on South Korea’s lunar orbiter Danuri, scientists now belief that there are no thick obvious deposits of water ice in in the permanently-shadowed interior of Shackleton Crater at the Moon’s south pole.
The image to the right combines pictures taken by Lunar Reconnaissance Orbiter (LRO) of the region around Shackleton with pictures produced by Shadowcam of its permanently-shadowed interior. From their paper’s conclusion:
The trailing (right) side of Shackleton’s interior is warmer owing to the secondary illumination asymmetry and floor topography. Illumination at the floor of Shackleton is patchy and possibly indicates a similar patchy (50 m scale) temperature distribution, which could mean a spatially irregular concentration of cold-trapped volatiles at the subsurface or mixed with regolith.
According to our Shackleton crater interior mapping from ShadowCam images, there is no observed evidence of thick ice deposits or surface ice that could be easily recognized by any relative brightness features observed in multiple illumination geometries. However, this analysis did not include the estimation of reflectance, nor did it involve reviewing all of the images of Shackleton in this preliminary study. Our hypothesis, in the context of water frost detections in Shackleton, is that if ice or frost is present in Shackleton’s interior, then the concentrations are either below the threshold that results in an observable signature in ShadowCam images, or might be mixed with the regolith at the detected areas. At other places where surface temperatures are below 110K, water frost could be hidden in subsurface layers.
The paper’s main purpose was to identify the dim lighting sources within the crater, all of which come from light bouncing off other surfaces. In the process the scientists obtained a better understanding of the surface itself.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Click for original image.
Using the low-light image produced by the American Shadowcam instrument on South Korea’s lunar orbiter Danuri, scientists now belief that there are no thick obvious deposits of water ice in in the permanently-shadowed interior of Shackleton Crater at the Moon’s south pole.
The image to the right combines pictures taken by Lunar Reconnaissance Orbiter (LRO) of the region around Shackleton with pictures produced by Shadowcam of its permanently-shadowed interior. From their paper’s conclusion:
The trailing (right) side of Shackleton’s interior is warmer owing to the secondary illumination asymmetry and floor topography. Illumination at the floor of Shackleton is patchy and possibly indicates a similar patchy (50 m scale) temperature distribution, which could mean a spatially irregular concentration of cold-trapped volatiles at the subsurface or mixed with regolith.
According to our Shackleton crater interior mapping from ShadowCam images, there is no observed evidence of thick ice deposits or surface ice that could be easily recognized by any relative brightness features observed in multiple illumination geometries. However, this analysis did not include the estimation of reflectance, nor did it involve reviewing all of the images of Shackleton in this preliminary study. Our hypothesis, in the context of water frost detections in Shackleton, is that if ice or frost is present in Shackleton’s interior, then the concentrations are either below the threshold that results in an observable signature in ShadowCam images, or might be mixed with the regolith at the detected areas. At other places where surface temperatures are below 110K, water frost could be hidden in subsurface layers.
The paper’s main purpose was to identify the dim lighting sources within the crater, all of which come from light bouncing off other surfaces. In the process the scientists obtained a better understanding of the surface itself.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Bob,
Thanks so much. I have been waiting for the results of this effort.
Concur with pawn: I have been curious about what would be found. Many hopes dashed, for sure.
I can’t help but think: “What’s in the crater? The ShadowCam knows.”