Twin Moon Gravity Probes will Launch on September

The twin Gravity Recovery and Interior Laboratory spacecraft (nicknamed GRAIL) are poised to launch moonward on September 8 from the Cape Canaveral Air Force Station. After the probes lift off, the journey to the moon will last about 3 1/2 months. The GRAIL mission is designed to discover details of the moon’s gravity field from the inside out. The twin probes will fly in tandem to scan the lunar crust to the core, in hopes of collecting measurements for the most accurate gravitational  map  of   the  moon ever produced. GRAIL consists of two spacecraft which are mirror images of one another. According to Sami Asmar a member of the GRAIL science team, because of that they cannot be interchanged or switched and they will fly together   in   formation  transmitting radio information between the two spacecraft, which allows to peer into the moon from the core to the crust.

source:www.space.com