The permafrost - the foundation of the Arctic and Antarctic - is changing drastically. DLR researchers can use radar to precisely determine which layers of ice freeze and thaw and when. This is important in order to better understand the interplay with climate change and derive recommendations for action. In Canada's Arctic, the DLR PermaSAR project team tested new radar technologies that allow us to see into the permafrost ground. The results will also serve future satellite missions for Earth observation, such as the proposed Tandem-L mission.