Post date: Dec 17, 2012 3:4:39 PM
The twin Gravity Recovery and Interior Laboratory, or GRAIL, spacecraft will make suicidal plunges into a mountain near the moon's north pole, a site selected to avoid the chance of hitting any of the Apollo or other lunar relics.
The impacts will take place about 20 seconds apart at 5:28 p.m. EST. The two spacecraft, each about the size of a small washing machine, have been flying in close formation around the moon for nearly a year to map the lunar gravity.