With its protective sea ice barrier melted away, Antarctica's Pine Island Glacier grows ever closer to finally dropping its New York City-sized iceberg into the ocean, according to NASA.

The giant crack in Pine Island Glacier was first spotted by scientists with NASA's IceBridge mission in 2011 as they surveyed the massive ice shelf in their specially equipped DC-8 plane. A second rift also formed and joined the northern side of the crack in May 2012, as captured on satellite images that track the incipient iceberg.

When IceBridge scientists returned this month, they discovered the original rift now has only about half a mile (less than 1 kilometer) to go before the 300-square-mile (770 square kilometers) berg forms.