Scientists got their first up-close look at what's eating away part of Antarctica's Thwaites ice shelf, nicknamed the Doomsday Glacier because of its massive melt and sea rise potential, and it's both good and bad news.

Using a 13-foot pencil-shaped robot that swam under the grounding line where ice first juts over the sea, scientists saw a shimmery critical point in Thwaites' chaotic breakup, "where it's melting so quickly there, there's just material streaming out of the glacier," said robot creator and polar scientist Britney Schmidt of Cornell University.

Before, scientists had no observat...