NASA GRAIL mission: another delay; now due to launch Saturday

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NASA postponed its GRAIL mission to the moon for the second time in two days Friday, and said it would try to launch again Saturday, weather permitting.

The agency said that a technical data issue had arisen when fuel and oxidizer were removed from the tanks that will power GRAIL’s Delta II rocket. The issue was discovered after high winds forced the first postponement, on Thursday.

NASA said there is a 60% chance that weather conditions will be favorable for a Saturday morning launch at Cape Canaveral, Fla. There will be plenty of chances; the launch window for GRAIL lasts until mid-October.

The two mirror-opposite spacecraft that comprise the Gravity Recovery and Interior Laboratory mission are scheduled to arrive at the moon on New Year’s Eve and New Year’s Day -- a schedule that is not expected to change even if there are further weather delays. GRAIL-A and GRAIL-B will spend three months making 12 polar orbits of the moon each day.

Scientists predict the mission will provide a comprehensive map of the moon’s gravitational field, allowing them to better calculate the composition of its crust, mantle and core and adding to their understanding of the evolution of the rocky planets.

The mission will also mark the first use of a technique known as ‘precision formation flying’ beyond Earth’s orbit. Some scientists say that technology, using multiple, coordinated spacecraft to study the same point in space in great detail, will provide many advances in space exploration in coming years.

The Jet Propulsion Laboratory in La Cañada Flintridge is managing the $496-million GRAIL mission.

Good progress made on Texas blaze

NASA delays GRAIL mission to the moon because of winds

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--Scott Gold