   #copyright

Shackleton (crater)

2007 Schools Wikipedia Selection. Related subjects: Space (Astronomy)

   Crater characteristics
   South lunar pole.
   South lunar pole as imaged by Clementine. Shackleton is in the small,
   dark patch at centre. NASA photo.
   Coordinates 89.9° S, 0.0° E
   Diameter 19 km
   Depth 2 km
   Colongitude   0° at sunrise
   Eponym Ernest Shackleton

   The Shackleton crater lies at the south pole of the Moon. 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 small
   and is viewed edge-on in a region of rough, cratered terrain. Detailed
   mapping of the terrain in the vicinity did not occur until the advent
   of orbiting spacecraft.

   The Shackleton crater 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. 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.

Exploration

   During the Lunar Prospector, the Neutron Spectrometer instrument on
   board the spacecraft appeared to detect excess hydrogen about the
   northern and southern lunar poles, including the crater Shackleton. In
   July, 1999, however, the impact of the Lunar Prospector in the nearby
   Shoemaker crater did not produce any detectable plume that might reveal
   resulting water vapor. This may be an indication that the hydrogen is
   not in the form of hydrated minerals, or else the point of site did not
   contain any ice.

   From the images of the crater edge taken from orbit, Shackleton appears
   to be a relatively young crater. The edges are clean and not
   significantly worn. A young crater would indicate that the inner sides
   are relatively steep, which may make traversing the sides relatively
   difficult for a robotic vehicle. In addition, the interior floor is not
   likely to have collected many volatiles since the crater creation.
   However other craters in the vicinity are considerably older, and may
   have collected significant deposits of hydrogen. (See Shoemaker crater,
   for example.)

   Radar studies following the Lunar Prospector mission demonstrate that
   the inner walls of Shackleton is similar in reflective characteristics
   to the surrounding regolith and similar, but sunlit craters with
   comparable features. The surroundings appear to contain a number of
   blocks that landed in the area as ejecta from impacts such as created
   the Mare Orientale basin.

   In 2006, NASA announced that a secondary payload would accompany the
   Lunar Reconnaissance Orbiter. This device, known as the Lunar Crater
   Observation and Sensing Satellite ( LCROSS) will observe the impact of
   the EDUS (Earth Departure Upper Stage) within a crater at a lunar pole.
   Shackleton crater has been suggested as a potential target for this
   mission, but the final target has not yet been selected.

   After flying through the plume of debris, the LCROSS will subsequently
   impact in the same crater. The impacts will be monitored from Earth and
   satellites, with the goal of detecting water ice in the crater. The
   EDUS will impact at about 2.5 km/s., is expected to create an impact
   crater about 100 m in diameter and 5 m deep. The resulting debris
   should reach an altitude of approximately 50 km. The impact of the
   LCROSS should produce similar results.

Potential uses

   Because the orbit of the Moon is only tilted 1.5° from the ecliptic,
   the interior of this crater lies in perpetual darkness. Peaks along the
   rim of the crater are almost continually illuminated by sunlight,
   spending about 80-90% 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 could be
   converted into electricity using solar panels. 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
   −173 °C, or 100 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.
   Retrieved from " http://en.wikipedia.org/wiki/Shackleton_%28crater%29"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
   Documentation License. See also our Disclaimer.
