Following a formidable 106-day trek across the Arctic, which ended with the two Arctic Arc expedition members relying on Envisat images to guide them safely through disintegrating sea-ice, intrepid polar explorer Alain Hubert recently visited ESA to handover a unique set of snow-depth measurements. To coincide with the launch of the International Polar Year (IPY) 2007-2008, explorers ventured out onto the sea-ice to embark upon a trek from Siberia to northern Greenland via the North Pole — a route never before attempted.