- The most detailed analysis ever of the
Moon's mysterious polar regions has pinpointed the place best suited for
a future human base.
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- The site is on the rim of a crater called
Shackleton and meets two essential requirements. There is plenty of sunlight
around to generate solar energy and it is very close to a permanently-shaded
region, where ice is likely to be stored in deep freeze.
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- Ice would not only satisfy the thirst
of settlers but could be used to generate fuel for spacecraft.
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- Ice was discovered at the Moon's north
and south poles just over a year ago by the Lunar Prospector spacecraft.
It was hailed as a major discovery and has transformed plans to colonise
the Moon.
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- From its orbit, Lunar Prospector was
able to detect ice in the polar regions but not pinpoint the exact position
of the frozen water. Its orbit has been lowered in the past few weeks to
enable it to make more precise observations.
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- But the new information on the location
of the ice has come from data from a previous lunar mission - the highly
successful Clementine mission that observed the Moon for 71 days in 1994.
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- The sun almost never sets
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- Clementine took images of the south pole
every 10 hours for about two lunar days. Dr Ben Bussey of the European
Space Agency used the data to produce maps showing the percentage of time
that a point on the surface is illuminated during a lunar day.
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- The maps reveal that no part of the south
pole is in constant sunlight but there are some areas that are almost in
the permanent glare of the Sun.
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- The rim of the Shackleton crater is a
particularly interesting place because it is illuminated more than 80%
of the time. Nearby there are two other places, only 10 km apart, which
collectively receive illumination more than 98% of the time.
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- Also not far away, down in the crater
itself, are regions of permanent shadow where ice could remain unmelted
by the Sun.
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- Electricity grid
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- This is the area to put the first Moonbase.
Electricity-producing solar arrays could be placed in the bright areas
and connected by a microwave or cable link. Then the Shackleton crater
site would receive near constant solar energy, as well as having easy access
to the lunar ice resources.
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- The Moon's north pole is a smoother place
than the south pole, but early estimates suggest that there could be up
to 13,000 square kilometres of permanent shade there.
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- Clementine was put into a polar orbit
from where it provided the first digital images of the Moon's poles. The
earlier Apollo missions were in an equatorial orbit to make it easier to
get the astronauts back to Earth in an emergency.
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- No seasonal difference
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- The Moon's axis of rotation, unlike the
Earth's, is not markedly tilted compared to its orbit around the Sun. This
means that the Moon does not have strongly different seasons and that the
Sun never rises very far up in the polar skies.
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- If you stood at the lunar poles for a
whole year the Sun would only move up or down about 1.5 degrees. This means
that low places close to the pole, such as the floors of craters, may never
see the Sun at all.
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- Scientists believe that any regions of
permanent shadow are prime candidates for the location of ice deposits.
They would act as cold traps for water molecules deposited billions of
years ago by impacting comets. A sizeable amount of ice may have built
up over the four billion year history of the Moon.
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- This latest analysis of the lunar poles
has highlighted their importance. Astronomers are now eagerly awaiting
the new results from the Lunar Prospector spacecraft.
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