CBS News
By Duarte Dias
Updated on: November 27, 2024 / 11:46 AM EST / CBS News
As NASA scientist Chad Greene flew over northern Greenland with a team of engineers in April, they never expected their radar to find something manmade buried deep within the ice. Greene and his team were flying above the Greenland Ice Sheet on a NASA Gulfstream III plane, scanning the barren expanse of ice that’s more than a mile deep in some areas, when their radar instrument picked up something unusual.