A Delta 2 heavy launch vehicle with NASA's GRAIL mission to the moon remains sits on launch pad 17B at Cape Canaveral, Florida. NASA has postponed until Saturday its next attempt to launch a $500 million pair of unmanned spacecraft that will use gravity tools to map the Moon's inner core for the first time.

NASA has postponed until Saturday its next attempt to launch a $500 million pair of unmanned spacecraft that will use gravity tools to map the Moon's inner core for the first time.

The launch team said early Friday it needed more time to review technical data following the de-tanking operation of the Delta II rocket carrying NASAs Gravity Recovery and Interior Laboratory (GRAIL).

"The postponement will allow the launch team additional time to review the data," said in a statement.

Saturday's two launch windows open at 8:29 am (1229 GMT) and 9:08 am (1308 GMT) at in Florida.

High winds delayed the first attempt moments before takeoff on Thursday.

The weather forecast for Saturday is 60 percent favorable for launch, up from 40 percent on Thursday and Friday, the US space agency said.

Scientists hope the satellites will help them understand how the Moon formed and whether there was once another Moon that melded with it, forming lunar mountains.