UNUSUAL RADAR ECHOES FROM THE GREENLAND ICE-SHEET

Airborne radar images of part of the Greenland ice sheet reveal icy te rrain whose radar properties are unique among radar-studied terrestria l surfaces but resemble those of Jupiter's icy Galilean satellites. Th e 5.6- and 24-centimeter-wavelength echoes from the Greenland percolat ion zone, like the 3.5- and 13-centimeter-wavelength echoes from the i cy satellites, are extremely intense and have anomalous circular and l inear polarization ratios. However, the detailed subsurface configurat ions of the Galilean satellite regoliths, where heterogeneities are th e product of prolonged meteoroid bombardment, are unlikely to resemble that within the Greenland percolation zone, where heterogeneities are the product of seasonal melting and refreezing.