Greenland’s ice may be hiding more than one crater left by long-ago meteorite impacts.
An analysis of satellite and airborne images of the topography beneath the ice sheet has revealed a large, craterlike structure buried beneath two kilometers of ice. It’s just 183 kilometers southeast of Hiawatha, another possible large impact crater described in November (SN: 12/8/18, p. 6). The newfound bowl-shaped object is about 36.5 kilometers across, slightly larger than the 31-kilometer-wide Hiawatha depression, researchers report online February 11 in Geophysical Research Letters.
Like Hiawatha, the new feature consists of a ring-shaped rim surrounding a depression with a peak at its center — consistent with a crater carved out by the impact of a large meteorite, says coauthor Joseph MacGregor, a glaciologist with NASA’s Operation IceBridge. Unlike Hiawatha, there’s little chance of collecting geologic data from the new structure to confirm or deny an extraterrestrial origin: Instead of sitting at the edge of the ice sheet, the new depression is closer to the center of the ice.
Without more direct geologic data, scientists can’t estimate its age or determine whether the two might be related to the same event. To assess how likely it is that two unrelated large impacts could have happened so close together on Earth’s surface, the team used a type of probability analysis previously used to assess the frequency of large impacts on Earth (SN Online: 1/17/19). The researchers determined that there could be a couple of large unrelated crater pairs on Earth separated by fewer than 183 kilometers.
“It’s simply not that unusual,” says coauthor William Bottke, a planetary scientist at the Southwest Research Institute in Boulder, Colo. Scientists already know of two such pairs — one in Ukraine and another in Canada — but, statistically, a third pair is plausible too, Bottke says.