GRAIL-A is scheduled to reach the moon on New Year's Eve 2011, while GRAIL-B will arrive New Year's Day 2012. The two solar-powered spacecraft will fly in tandem orbits around the moon to measure its gravity field. GRAIL will answer longstanding questions about the moon and give scientists a better understanding of how Earth and other rocky planets in the solar system formed.
"If there was ever any doubt that Florida's Space Coast would continue to be open for business, that thought was drowned out by the roar of today's GRAIL launch," said NASA Administrator Charles Bolden. "GRAIL and many other exciting upcoming missions make clear that NASA is taking its next big leap into deep space exploration, and the space industry continues to provide the jobs and workers needed to support this critical effort."
The spacecraft were launched aboard a United Launch Alliance Delta II rocket. GRAIL mission controllers acquired a signal from GRAIL-A at 10:29 a.m. EDT (7:29 a.m. PDT). GRAIL-B's signal was received eight minutes later. The telemetry downlinked from both spacecraft indicates they have deployed their solar panels and are operating as expected.