NASA Radar finds water ice at the North Pole of the Moon

by S. C.

Although the total amount of ice depends on its thickness in each crater, a fact that is not yet known, it is estimated that there could be at least 600 million tons of frozen water in the craters of the lunar North Pole.

Frozen water on the Moon: Using data from a radar built by NASA, who went to space on board the Indian spacecraft Chandrayaan-1, scientists found large deposits of ice near the North Pole of the Moon

The analysis confirms the results obtained by another instrument of the Indian spacecraft, which had already found signs of water molecules on the moon, but without quantifying the occurrences.
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The Mini-SAR instrument, a small radar (less than 10 kg) of synthetic aperture, found more than 40 small craters in water ice. The craters range in size from 2 to 15 km diameter.

Although the total amount of ice depends on its thickness in each crater, a fact that is not yet known, it is estimated that there could be at least 600 million tons of frozen water in the craters of the lunar North Pole.
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The Mini-SAR photographed many of the permanently shadowed regions that exist at both poles of the Moon These dark areas are extremely cold, leading scientists to raise the hypothesis that volatiles, including water ice – in the cold of space there is ice other materials – could be present in large quantities there.

The main scientific objective of the Mini-SAR was just to map and characterize any deposit that actually existed in these areas.
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The Mini-SAR uses the polarization properties of radio waves reflected from the surface to characterize the properties of the material on this surface – it emits radar pulses are circularly polarized to the left.

The planetary surfaces typical reverse bias during the reflection of radio waves, so that the echoes of the normal signs of the Mini-SAR is the right circularly polarized. The relationship between the received power in the same direction of transmission (move left) and received power in the opposite direction (move right) is called the rate of circular polarization (CPC).

Most of the lunar surface has a low CPC, which means that the rule is the reversal of polarization. But some targets of Chandrayaan-1 showed a high CPC. Among these targets were very recent and surfaces rough (like a young crater) and ice that is transparent to radio waves, scattering wide wrists – this leads to an increase in the reflections in the same direction and therefore a more TPC high.

This leads to the calculation of an estimated amount of water ice, potentially present, scientists say, which is comparable to the amount estimated from the data collected by another recent mission to the moon, the LCROSS, which caused great disappointment in not generate a awaited cloud of dust when hitting the moon, but found signs that not only water but also some intriguing substances that scientists have not yet revealed what they are.

Data from the LCROSS led to an estimated “several hundred million tons of water ice, while data from Chandrayaan-1 now speak more precisely at 600 million tons of lunar ice.

The variation in estimates between the Mini-SAR and the neutron spectrometer of LCROSS is due to the fact that the latter reaches depths of only about five feet, which would underestimate the total amount of water ice present. Moreover, at least part of the lunar polar ice must be mixed with lunar soil and, therefore, invisible to radar.

by S. C.
07 March 2010 Teatro Naturale International n. 3 Year 2

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