Saturday's GRAIL Launch. Photo courtesy NASA.

“GRAIL, simply put, is a journey to the center of the Moon,” announced Edward Weiler, NASA’s Associate Administrator for the Science Mission Directorate, after Saturday’s launch of the twin spacecraft that constitute the Gravity Recovery And Interior Laboratory (GRAIL) mission. DTM Director Sean Solomon, a Co-Investigator on the GRAIL mission, witnessed the launch from the Cape Canaveral Air Force Station in Florida.

After delays due to high-altitude winds, GRAIL was successfully launched on a Delta II rocket at 9:08 a.m. EDT. The two spacecraft will spend three-and-a-half months en route to the Moon via the Sun-Earth L1 Lagrange point, a route selected to reduce fuel requirements and permit more time for spacecraft outgassing and checkout.  Orbit insertion will occur on 31 December 2011 and 1 January 2012.

The goal of the GRAIL mission is to measure the gravitational field of the Moon to unprecedented accuracy by tracking the small perturbations to the distance between the two spacecraft in lunar orbit. Solomon is a member of the science team now preparing to analyze and interpret the GRAIL observations in terms of the internal structure and evolution of the Moon. The team is led by Principal Investigator Maria Zuber of MIT.

“Witnessing the launch of a spacecraft bound for another solar system object is always an amazing thrill,” says Solomon. “We are fortunate to live during the opening of the era of space exploration, when every visit to one of our solar system neighbors brings new discoveries. The investigation of the Moon and the inner planets is in many ways an extension of our study of our own planet and will deepen our understanding of how Earth formed and evolved.”