"The crater is exceptionally well-preserved and that is surprising..." - Professor Kurt Kjaer, lead author of the study.
"The survey exceeded all expectations and imaged the depression in stunning detail." - Joe MacGregor, Glaciologist at Goddard Space Flight Center.
The Impact Crater and the Younger Dryas
Sources:
NASA Press Release: International Team, NASA Make Unexpected Discovery Under Greenland Ice
Research Paper: A large impact crater beneath Hiawatha Glacier in northwest Greenland
Research Paper: Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling