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New evidence points towards water on Moon | Two separate lunar missions have found evidence which indicates that the polar regions of the moon are chock full of water-altered minerals. According to a report
in Nature News, early results from NASA's Lunar Reconnaissance Orbiter (LRO),
launched on June 18, are offering a wide array of watery signals. The Moon, in
fact, has water in all sorts of places: not just locked up in minerals, but scattered
throughout the broken-up surface, and, potentially, in blocks or sheets of ice
at depth. "We are on the verge of a renaissance in our thinking about the poles
of the Moon, including how water ice gets there," said Anthony Colaprete, principal
investigator for the Lunar Crater Observation and Sensing Satellite (LCROSS),
which on October 9, will slam into a polar crater with the intention of ploughing
up a plume of water ice for many telescopic eyes to see. The initial LRO results
confirm what was long suspected as a way for ice to stay trapped on the Moon for
billions of years. A thermal mapping instrument showed that permanently shadowed
regions within deep polar craters are as cold as 35o Kelvin (-238o Celsius). Project
scientist Richard Vondrak said that they are the coldest spots in the Solar System
- even colder than the surface of Pluto. Variations in the flux of neutrons suggests
variability in water content among craters. But, the surprise comes from a different
instrument on LRO, which counts slow-moving neutrons as a way of measuring hydrogen
abundance in the top metre or so of the surface. This hydrogen is often interpreted
as a proxy for water ice, although it could also be molecular hydrogen or hydrogen
trapped in other molecules. The LRO instrument has already found a significant
excess of hydrogen at the poles. But, with added resolution, it is seeing surprising
variability within the polar regions. Some of the craters appear enriched in hydrogen.
Others are not. Stranger still, some areas outside the crater walls, which were
thought to get too hot for water to linger, show an excess of hydrogen. Vondrak
said this shows that the water could have arrived more recently, or that it can
persist if buried as impacts till the lunar soil. If the LCROSS impact spews up
ice, it will eliminate the last vestiges of doubt about water on the Moon. It
could also start a new hunt: to find a record of impact events, such as water-rich
comet strikes, that put the ice there in the first place. |
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