AAE Colloquium: Dr. H. Jay Melosh

Event Date: March 13, 2014
Hosted By: School of Aeronautics and Astronautics
Time: 3:00 p.m.
Location: ARMS 1109

Probing Behing the Man in the Moon: NASA's GRAIL Mission and It's Early Results

Dr. H. Jay Melosh
University Distinguished Professor Earth, Atmospheric, and Planetary Sciences
Purdue University

NASA’s GRAIL mission to the Moon was completed in 2012 when both spacecraft were intentionally “de-orbited” (i.e. crashed) into a nearside mountainside. This orbital mission measured tiny variations in the Moon’s gravitational field by continuously monitoring the distance between two co-orbiting spacecraft (dubbed Ebb and Flow) to a precision of less than 0.1 micron. The resulting enormous improvement in the gravity field reveals buried structures otherwise hidden from view, from the underpinnings of large impact scars and the nearside lava flows down to a detection of the Moon’s core and perhaps an inner core. We have finally achieved a clear understanding of the previously mysterious mascons that posed a navigational hazard to the Apollo spacecraft and can now document a complete catalog of all of the ancient and, in many cases, otherwise invisible scars of large impacts that have breached the Moon’s crust. The Moon’s gravity field turns out to be qualitatively different from that of the other terrestrial-type planets in our solar system.

H. J. Melosh is a Distinguished Professor of Earth and Atmospheric Science, Physics and has a courtesy appointment in AAE at Purdue. He received an AB degree in Physics from Princeton University in 1969 and a PhD in Physics and Geology from Caltech in 1973. His principal research interests are impact cratering, planetary tectonics, and the physics of earthquakes and landslides. His recent research includes studies of the giant impact origin of the moon, the K/T impact that extinguished the dinosaurs, the ejection of rocks from their parent bodies and the origin and transfer of life between the planets. He is a science team member of NASA’s Deep Impact mission that successfully cratered comet Tempel 1 on July 4, 2005 and flew by comet Hartley 2 on November 9, 2010. He is also a Co-Investigator of the GRAIL mission that completed its mapping mission of the Moon in December, 2013 and returned detailed data on its gravity field, which is still being analyzed.
Professor Melosh is a Fellow of the Meteoritical Society, the Geological Society of America the American Geophysical Union and American Association for the Advancement of Science. He was awarded the Barringer Medal of the Meteoritical Society in 1999, the Gilbert prize of the Geological Society of America in 2001 and the Hess Medal of the American Geophysical Union in 2008. He was a Guggenheim Fellow in 1996-1997 and a Humboldt Fellow at the Bavarian Geological Institute in Bayreuth, Germany, in 2005-2006. Asteroid #8216 was named “Melosh” in his honor. He was elected to the U.S. National Academy of Sciences in 2003 and the American Academy of Arts and Sciences in 2011.
He has published approximately 180 technical papers, edited two books and is the author of a major monograph, Impact Cratering: A Geologic Process and a text “Planetary Surface Processes” with Cambridge University Press.

Please see the Colloquium Announcement for more details.