GRAIL probes with North Alabama ties get closer to lunar orbit

This undated artist rendering provided by NASA on Dec. 21,2011 shows the twin Grail spacecraft mapping the lunar gravity field. The two probes are scheduled to enter orbit around the moon over New Year's weekend. (AP Photo/NASA, Jet Propulsion Laboratory)

HUNTSVILLE, Alabama -- The possibility of gathering unprecedented scientific data on the moon draws closer as twin probes with ties to North Alabama approach earth's celestial neighbor.
The twin GRAIL probes are scheduled to go into lunar orbit on Friday and Saturday, which ultimately will bring the tiny probes to within 34 miles of the surface.
GRAIL, which stands for Gravity Recovery and Interior Laboratory, was launched Sept. 10 on a Delta II rocket built in Decatur at the United Launch Alliance facility. The probes are part of NASA's Discovery Program, which is overseeing the mission and is managed at Marshall Space Flight Center.