Not much ice in southern lunar craters
New high-resolution radar measurements have failed to detect water ice in the permanently dark craters at the Moon's south pole. Instead, the scientists led by Donald Campbell from Cornell University also registered those signals in sunlit areas that had previously been taken as signs of water.
The researchers used the Green Bank radio telescope to pick up radar echoes of a signal sent from the world's largest telescope in Arecibo, Puerto Rica, towards the lunar south pole. In the depths of the craters there, some of which are constantly in the shade and where temperatures are below minus 170 degrees Celsius, astronomers had previously suspected significant amounts of frozen water. Most recently, the Lunar Prospector probe had found evidence of high concentrations of hydrogen.
The interpretation that it could be water is now dampened by the radar measurements with a spatial resolution of twenty meters. For the first time, the researchers were able to show that the observed polarization of the signal occurs not only in the shadowy areas of Shackleton Crater, but also in regions exposed to sunlight. It is therefore not an indication of ice.
The knowledge should affect Nasa's plans for another moon landing and the establishment of a moon base. Engineers can no longer hope for significant water reserves at the South Pole.
