Moon countdown: NASA probe prepares to enter orbit

LOS ANGELES (AP) ? One of two NASA spacecraft bound for the moon is about to arrive.

The probe named Grail-A fired its engine Saturday, slowing its speed to slip into lunar orbit on New Year’s Eve.

The maneuver was expected to last about 40 minutes.

Deep space antennas in the California desert and Madrid are keeping tabs on the spacecraft and feeding real-time information to ground controllers.

Its twin Grail-B will execute the same move on New Year’s Day.

The $496 million mission will measure the moon’s lumpy gravity field to determine what’s inside straight down to the core.