Photo Details

Photo detail

September 8, 2011

This framegrab image from NASA-TV shows the twin GRAIL satellites sitting on launch pad 37-A at the 15-minute hold mark atop a United Launch Alliance Delta II rocket Thursday Sept. 8, 2011. NASA is sending the probes on a long, roundabout trip to the moon. The spacecraft will orbit the moon, chasing one another in circles so researchers can measure the gap and the gravity below. It will be the first lunar mission devoted to studying the insides of the moon. By measuring the entire gravity field of the moon, scientists hope to learn what the moon is made of all the way to its core. (AP Photo/NASA)