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Дата изменения: Unknown
Дата индексирования: Wed Apr 13 09:31:29 2016
Кодировка: IBM-866

Поисковые слова: ngc 7023
The Moon National Astronomy and Ionosphere Center (Arecibo Observatory)

The Moon

The discovery of ice at the poles of Mercury triggered a search for ice in the shadowed floors of craters near the lunar poles as part of Cornell graduate student, Nick Stacy's Ph.D. thesis work. Stacy developed sophisticated data acquisition and analysis techniques to image selected regions of the Moon in all four Stokes' polarization parameters at resolutions down to 20 m using the 430 MHz radar system. No clear evidence of ice was found, although there are a small number of areas of anomalous backscatter at the south pole, which warrant further study. These lunar observations have, for the first time, demonstrated the capability for radar measurements to map, assuming a scattering model for the surface, variations in mare surface dielectric constant and areas with high concentrations of titanium or iron oxides.€а

This radar image in delay-Doppler coordinates of the south pole region of the Moon was made at Arecibo in a search for ice in permanently shadowed areas. It is 400 km in each coordinate and the original image has a resolution of 500 m in delay (vertical) and 580 m in Doppler (horizontal). The illumination is from the top (so range increases downward), and increasing Doppler frequency is towards the left. The approximate location of the south pole is indicated by the cross. The search was for the characteristic radar signature of ice, high backscatter cross section and high circular polarization ratio. No clear indication of ice was found, although a small number of areas with anomalous radar properties need further investigation. These lunar investigations were done by N. J. Stacy as part of his Cornell Ph.D. thesis.€а