Probes to crash on moon today; Purdue professor and mission scientist will be watching

WEST LAFAYETTE, Ind. — Twin satellites that revealed the most detailed map of the moon ever recorded will crash into the moon's surface on Monday (Dec. 17), and a group that includes a Purdue University professor who is part of the mission will be watching.

Jay Melosh, a distinguished professor of earth and atmospheric sciences and physics, is a member of the science team for NASA's unmanned Gravity Recovery and Interior Laboratory, or GRAIL, lunar mission. He will be part of a viewing party at 5 p.m. in Hampton Hall, formerly the Civil Engineering Building, Room 2201. The impact is estimated to occur at around 5:28 p.m., and NASA is presenting a live stream of the event beginning at 5 p.m. on NASA TV at http://www.nasa.gov/multimedia/nasatv/index.html

The GRAIL mission relies on twin satellites that orbited the moon for several months to map its gravity field and reveal subsurface structures. Gravitational variations as the satellites flew about 50 kilometers from the surface revealed distributions of mass and, in essence, provided an X-ray of the moon.

Melosh is an expert on impact cratering and is involved in the analysis and modeling of these mass concentrations and the subsurface structures of the craters scattered across the moon's surface.

The craters left behind by an impact provide insight into the moon's composition, such as the thickness of the crust and its temperature at the time of impact. Learning more about the mechanics of crater formation will help explain how planets respond to large impacts, how craters influence crust formation and the early processes that form the surface of a planet, Melosh said.

Maria Zuber of the Massachusetts Institute of Technology leads the GRAIL mission. Mission partners include NASA, JPL, Lockheed Martin, MIT and Goddard Space Flight Center.

Writer: Elizabeth K. Gardner, 765-494-2081, ekgardner@purdue.edu

Source: Jay Melosh, 765-494-3290, jmelosh@purdue.edu

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