NASA launches twin lunar probes

NPR : On Saturday NASA launched a pair of probes to measure the Moon’s gravity and core. Grail-A and Grail-B, part of the Gravity Recovery and Interior Laboratory mission, were launched together aboard a small Delta II rocket but will travel independently to the Moon. The probes will take a leisurely four months to reach their destination in order to save fuel, protect their instruments, and reduce the spacecraft’s velocity on arrival. The Grail spacecraft, each of which is the size of a washing machine, won’t land on the Moon but will conduct their research from low lunar orbit of about 55 km above the surface. “We will learn more about the interior of the moon with Grail than all previous lunar missions combined,” said Ed Weiler, head of NASA’s science mission directorate.