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Shackleton (Crater)Shackleton is a lunar crater that lies at the south pole of the Moon. In fact, the pole lies within the rim of the crater, and is only a few kilometers from the mid-point. From the perspective of the Earth, this crater lies along the limb of the Moon, making observation difficult. The crater is relatively small and is viewed edge-on in an region of rough, cratered terrain. Detailed mapping of the terrain in the vicinity did not occur until the advent of orbiting spacecraft. The crater Shackleton lies entirely within the rim of the immense South Pole-Aitken basin, the largest known impact formation in the Solar system. This basin is over 12 kilometers deep, and an exploration of its properties could provide useful information about the lunar interior. Nearby craters of note include the Shoemaker, Sverdrup, De Gerlache, and Faustini craters; all located north of Shackleton. Somewhat further away, on the eastern hemisphere of the lunar near side, are the larger Amundsen and Scott craters, named for two other early explorers of the Antarctic continent. Potential uses Because the orbit of the Moon is only tilted 1.5° from the ecliptic, the interior of this crater lies in perpetual sunlight. Peaks along the rim of the crater are almost continually illuminated by sunlight, spending about 80% of each lunar orbit exposed to the Sun. (Such a mount has been termed a Peak of Eternal Light, and such a formation has been predicted since the 1900s.) Due to this almost constant illumination, the crater rim is considered a preferable location for a future lunar outpost. The light can be converted into energy using solar panels, providing electricity for all necessary purposes. The temperature at the location is also more favorable than on most of the surface, and does not experience the extremes along the lunar equator where it rises to 100° C when the Sun is overhead, to as low as -150° C during the lunar night. The continuous shadows in the south polar craters cause the floors of these formations to maintain a temperature that never exceeds about -230° C, or 43° K. Any water vapor that arrives here due to a cometary impact would lie permanently frozen on or below the surface. This suggests that the crater floors could potentially be "mined" for deposits of hydrogen in water form, a commodity that is expensive to deliver directly from the Earth. While scientific experiments performed by the Clementine and the Lunar Prospector could indicate the presence of water in the polar craters, the current evidence is far from definitive. There are doubts among scientists whether significant quantities of water are located in these craters. Resolution of this issue will require a future mission to the Moon. This crater has also been proposed as a future site for a large infrared telescope. The low temperature of the crater floor make it ideal for infrared observations, and solar cells placed along the rim could provide near-continuous power to the observatory. About 120 kilometers from the crater lies the 5-km-tall Malapert Mountain, a peak that is perpetually visible from the Earth, and which could serve as a radio relay station when suitably equipped. References - D. B. J. Bussey, M. S. Robinson, P. D. Spudis, Ideal Landing Sites Near the Lunar Poles, Lunar and Planetary Science XXXV, 2004.
- P. J. van Susante, Design and Construction of a Lunar South Pole Infrared Telescope, COSPAR 2002.
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