September 26, 2018

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Too Much Resolution?

Originally published July 13, 2009 LPOD-July13-09.jpg
LRO NAC image from LROC Browse Gallery

We are all amazed when amateur Moon imagers achieve a resolution of 500 to 600 m. Increasing resolution to 100 m with Lunar Orbiter, Kaguya, Clementine and various other satellites leads to a significant improvement in interpretability. Imagine then the vast increase in understanding to come from the 0.5 m resolution of the Lunar Reconnaissance Orbiter. The image above is a full resolution excerpt of a LRO Narrow Angle Canera (NAC) image near the old highlands crater Deluc M. The image width is about 600 m - this is one image element for the best images from Earth. But we can not interpret this image the way we do lower resolution images. True, we can see and understand the hundreds of impact craters that are a few 10s of meters in diameter. But beyond that we apparently don't see primary structures but rather some odd modification of the regolith surface that is called elephant hide or tree bark texture. No one knows what causes this, but nearly every surface on the Moon has been modified to have a similar texture. This means that the very highest resolution may not help very much to improve the geologic understanding of craters, domes, rilles, or other features that are old enough to have the tree bark texture. Very young impact craters will be seen in their pristine glory and we will certainly see the left behind equipment and debris of previous spacecraft crashes and landings. And at 50 cm resolution we can also expect to learn unexpected things. But it may be that the narrow (5 km) strips from NAC will be mosaicked together to cover larger areas and that we may choose to reduce the resolution to 10 or 20 m to blur out the hyoer-details of tree bark to see the geologic structures.

Chuck Wood

Technical Details
Jun 30 15:22:01 UTC 2009. Center Longitude -5.55°, Center Latitude -54.96°. Resolution 56 cm/pixel

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Rükl plate 73

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