Artist concept of GRAIL mission. Grail will fly twin spacecraft in tandem orbits around the moon for several months to measure its gravity field in unprecedented detail. © NASA/JPL

BEIJING, Sept. 6 — NASA will launch on Thursday twin lunar orbiters built to map the gravity of Earth’s moon in unprecedented detail, media reported Tuesday.

The twin lunar probes, Graili-A and Graili-B, will blast off from Florida’s Cape Canaveral Air Force Station at 8:37 a.m. EDT and at 9:16 a.m. EDT respectively Thursday, according to NASA.

The Grail twins will travel three to four months to get to the moon under a slower but more economical plan.

The two spacecrafts will reach the moon around New Year’s Day when they will begin to probe the moon’s composition from the crust to the core, according to NASA.

The data collected by the probes will be used to better understand the moon’s evolution and formation, NASA scientists said.

Researchers will also use the twin probes to pinpoint the best landing sites for future explorations.

The mission, from start to finish, costs 496 million U.S. dollars. The two Grail probes will crash into the moon after its mission. 

On Xinhua Web site: http://news.xinhuanet.com/english2010/sci/2011-09/06/c_131103031.htm