When we looked at Soviet lunar missions I showed the Luna 22 bistatic radar image of part of the Moon. It didn't tell us much we didn't know about the Moon (rocky surfaces and slopes facing the radar will reflect it on to the detector). But a year later Venera 9 used bistatic radar to study Venus, an utterly unknown surface, so in a sense the Luna 22 lunar data are like 'ground truth' for Venus. The results were published at the time in a Russian journal...
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