APOLLO 15 TRAVERSE MAPPING. P. J. Stooke1, 1Department Of

APOLLO 15 TRAVERSE MAPPING. P. J. Stooke1, 1Department Of

49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083) 1007.pdf APOLLO 15 TRAVERSE MAPPING. P. J. Stooke1, 1Department of Geography, and Centre for Planetary Sci- ence and Exploration, University of Western Ontario, London, Ontario, Canada N6A 5C2, [email protected], http://publish.uwo.ca/~pjstooke. Introduction: Apollo 15 landed at the Hadley- References: [1] Defense Mapping Agency, 1975. Apennine site on 30 July 1971. David Scott and Jim Apollo 15 Traverses. Lunar Photomap, scale 1:25000. Irwin explored the site for three days using a lunar rov- Washington, DC, April 1975. [2] Apollo Lunar Surface ing vehicle (LRV) before re-joining Al Worden in orbit. Journal. https://www.hq.nasa.gov/alsj/. [3] Stooke, P., The LRV traverses were portrayed in a map by the 2007. The International Atlas of Lunar Exploration. Defense Mapping Agency in 1975 [1], but that repre- Cambridge University Press, 2007. sentation has long been known to be somewhat inaccu- rate (see the Apollo Lunar Surface Journal coverage of Apollo 15, [2]). In particular the map showed EVA 2 passing west of the crater Earthlight when evidence suggested it passed to the east. Rover navigation sys- tem readings were too sparse to help very much, and the crucial 16 mm camera which was to record the traverse did not operate for most of the surface mis- sion. This study uses LROC images to map traverses, but even these show no tracks in many areas. Three other methods are used to improve traverse mapping. Shadow suppression: This method merges two im- ages with opposite (morning and afternoon) lighting. The rationale is that topography-related shading and highlights will cancel each other out (if only partially) while albedo markings are reinforced. Figure 1 shows an example, revealing tracks almost invisible in the in- dividual images. Good results can be obtained, but not in every situation. 16 mm image mapping: While northbound on the western rim of Dune crater, the 16 mm camera worked for a short time, providing a video record of the drive. Figure 1. Merging two LROC images with opposite Individual frames were extracted, contrast-stretched, lighting to suppress shadows and enhance tracks. and roughly reprojected (Figure 2) to compare with LRO images. This enabled detailed mapping of an oth- erwise completely invisible section of the traverse (Fig- ure 3). Crew description: Step by step comparison of the voice transcript and the LRO images often reveals de- tails of the path. Some examples are plotted on the map in Figure 3. Other examples include statements such as ‘a rather large [crater] out at 1 o'clock [out- bound]... a lot of angular blocks on the rim of it’ [just south of Elbow, EVA 1], and 'A very large depression here... let's go north of it' [EVA 3]. Results: The three EVAs have been mapped with Figure 2. 16 mm frames enhanced and roughly rec- only short gaps, and though not perfect, and still uncer- tified for mapping. West rim of Dune crater, looking tain in places, the results are probably superior to any- north. thing else available. The method has now been applied to Apollo 16 and will be used for Apollo 17 next year. Figure 3 (next page): Section of Apollo 15 EVA 2 The new maps will be made available to the Apollo map showing the area around Dune crater. White ar- Lunar Surface Journal and also published in an updated rows indicate unmapped parts of the traverse. version of [3]. 49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083) 1007.pdf .

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