Greenland's Hiawatha Crater

Ice-penetrating radar sends radio waves downward into the ice sheet and measures the energy reflected back from within the ice sheet and the ground beneath. The radar data detects layers in the ice generated by climate events in the past. The radar data ("radargrams") is then displayed on curtains in the location where it was observed showing the layers in the ice.

As the visualization shows the plane flying inland over Hiawatha Glacier, the ice sheet is cut away, leaving the radargram on the interior cutting plane. At this point, half of the depression of the Hiawatha impact crater is visible. A green grid fades in over the surface of the ice sheet showing the location of the flights that collected the radar data in spring 2016. The entire ice-sheet surface fades away and the full crater is visible as arrows point out the locations of the peaks in the central uplift and a red cylinder shows the best-fit rim of the impact crater. Radargram "curtains" fade on and are subsequently removed two at a time to allow examination of the structure of the ice that fills the crater. Note that the lower layers of ice near the crater floor appear disturbed, while the upper layers appear smooth and undisturbed.

Subsequent helicopter visits to the deglaciated terrain in front of Hiawatha Glacier by scientists from the Natural History Museum in Denmark recovered sediment samples from the main river that discharges water from beneath Hiawatha Glacier, through the northwestern rim breach. Laboratory examination revealed that these sediment samples contained shocked quartz and elevated platinum-group-element concentrations, both signs that the sediment records evidence of the impact of an iron asteroid more than one kilometer wide. The Hiawatha impact crater is potentially one of the youngest large impact craters on Earth.