https://phys.org/news/2018-11-huge-crater-greenland-impact-northern.html > It was identified with data collected between 1997 and 2014 by KU for NASA's Program for Arctic Regional Climate Assessment and Operation IceBridge, and supplemented with more data collected in May 2016 using the Multichannel Coherent Radar Depth Sounder (MCoRDS) developed at KU. > "We've collected lots of radar-sounding data over the last couple of decades, and glaciologists put these radar-sounding datasets together to produce maps of what Greenland is like underneath the ice," said co-author John Paden, courtesy associate professor of electrical engineering & computer science at KU and associate scientist at CReSIS. "Danish researchers were looking at the map and saw this big, craterlike depression under the ice sheet and looked at satellite imagery and—because the crater is on edge of the ice sheet—you can see a circular pattern there as well. The two combined made a really strong case for this being an impact-crater site. Based on this discovery, a detailed radar survey was conducted in May 2016 using a new state-of-the-art radar designed and built by KU for the Alfred Wegener Institute in Germany."