12/09/2011 09:54 BST | Updated 11/11/2011 10:12 GMT

NASA Launches Mission To The Moon

NASA launched its twin spacecraft Grail A and Grail B to the the moon on Saturday. The mission will examine the moon from crust to core, and will take four months reach earth's nearest neighbour before commencing the study.

"I could hardly be happier," said the lead scientist, Maria Zuber, told AP after two days of delays. "I was trying to be as calm as I could be."

The UK's Justine Mackinnon was a guest of NASA at the "tweet-up" event surrounding the launch. She tweeted, as @fidget02, "Wow wow wow I saw #GRAIL launch. Just cannot describe it!", while fellow tweeter Jim Stern tweeted "GRAIL A separation #GRAIL” #GRAIL #NASAtweetup This is awesome!"

A storm interfered with the broadcast of the launch and upper-level winds also delayed the launch, according the tweeter @elakdawalla.

The two Grail modules, both the size of a washing machine, were launched on the one rocket to save money. A is expcted to arrive on New Year's Eve and B on New Year's Day.

"Grail, simply put, is a journey to the center of the moon," said Ed Weiler, head of NASA's science mission directorate, borrowing from the title of the Jules Verne science fiction classic, "Journey to the Center of the Earth."

100 missions to the moon have been launched since the USSR's 1959 Luna probes.