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Using satelite up to 9m down under earth - P-band soon
Dan Blumberg and Julian Daniels of the Ben Gurion University of the Negev in Israel decided to
test the idea. They buried flat squares of aluminium at different depths under the sand in the Negev desert, then flew an aircraft over the area to carry out radar sensing of the layers beneath the surface. By comparing the radar results with the squares' known positions, the researchers showed that the patterns detected by the radar really did show the buried pieces of metal. 'Now we have systematic proof,' Blumberg told New Scientist. 'Buried objects can be detected from airborne systems.' For their experiments, they use microwaves of the longest possible wavelength, called P-band (see Graphic). At the moment, satellites generally use microwaves with shorter wavelengths because the resolution is better. But P-band radiation can penetrate farther underground, so Blumberg hopes that adding it to satellite sensors will allow them to probe deeper, perhaps up to 9 metres down. 'Using the P-band is quite new,' says Andrew Wilson, a remote-sensing expert for Britain's Natural Environment Research Council. 'It can penetrate the ground farther, so it would be good at revealing archaeological objects.'
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