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EVA 3 Station 9A - Observations of Hadley Rille
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EVA 3: Station 9A - Observations of Hadley Rille

November 29, 2012
The last EVA allowed the crew to explore the edge of Hadley Rille. The crew visited a fresh crater with a blocky texture, and a terrace at Station 9A that allowed Scott and Irwin a chance to peer down into the rille, which is approximately 1.3 km wide and 400 m deep along most of its length. The crew was able to observe and photograph bedrock along the upper part of the western rille wall. Test pilots by profession, the crew went through extensive geology training so that they could communicate their observations effectively and efficiently to the Science Backroom in Houston, Texas. Most of us are familiar with Neil Armstrong's "One small step..." quote. What is sometimes forgotten is that there was also a great deal of science being accomplished and discussed during the various missions. Field geologists normally have a field notebook to write down and draw their observations in, but on the Moon everything has to be described vocally. Here is an example from Commander Scott's geologic description of the rille wall at this location and one of the images that corresponds with it. Compare his description with the photograph and this panorama. 165:22:50 Scott: I can see from up at the top of the rille down, there's debris all the way. And, it looks like some outcrops directly at about 11 o'clock to the Sun line. It looks like a layer. About 5 percent of the rille wall (height), with a vertical face on it. And, within the vertical face, I can see other small lineations, horizontal about maybe 10 percent of that unit. 165:23:26 Scott: And that unit outcrops (at various places) along the rille. It's about 10 percent from the top, and it's somewhat irregular; but it looks to be a continuous layer. It may be portions of (mare basalt) flows, but they're generally at about the 10-percent level. I can see another one at about 12 o'clock to the Sun line, which is somewhat thinner, maybe 5 percent of the total depth of the rille. However, it has a more-well-defined internal layering of about 10 percent of its thickness. I can see maybe 10 very well-defined layers within that unit. Outcrop of basaltic lava exposed along the western wall of Hadley Rille. Photographed from Station 9A. Letters point to rocks seen in the LROC NAC frame below. Apollo 15 image AS15-89- 12115 Credit: NASA


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