The Canadian radar satellite, somewhat obviously called Radarsat, was used to create the first complete high-resolution mosaic of the Antarctic in 1997. By complete, that includes the polo-hole in the middle that a lot of satellites cannot see. Radarsat was flipped over in orbit to ensure it saw everything and the result was the RAMP mosaic.
Subsequently the process was (mostly) repeated in 2000 to create the MAMM dataset, which this time collected sufficient repeat data to derive a veolcity field from the data. This time round the in-orbit acrobatics were ruled out, so the polo-hole gap is missing coverage.
The folks at Byrd Polar Research Centre have recently updated the RAMP website and there is an abundance of information about the project, access to numerous datasets, publications and documentation.