David E. Smith was awarded the 2012 Charles A. Whitten Medal at the AGU Fall Meeting Honors Ceremony, held on 5 December 2012 in San Francisco, Calif. The medal is for “outstanding achievement in research on the form and dynamics of the Earth and planets.”
David Smith is a leader in satellite geodesy whose groundbreaking contributions have spanned tectonophysics, geodynamics, and planetary science. Born and educated in Great Britain, he joined NASA’s Goddard Space Flight Center in his early career, where he started the gravity modeling group. There he conceived of and developed Goddard’s GEODYN system of programs, which to this day is considered the state-of-the-art computational tool for satellite orbit determination. Dave was among the first to measure the fundamental parameters of the Earth’s global gravity field, as well as its polar motion and variations in length of day. Measurements of deviations from Earth’s geodetic reference frame that he was instrumental in establishing led to characterization of atmospheric motions, ocean and solid Earth tides, and the viscosity of the mantle.
A second major aspect of Dave’s work has been in measuring directly the motions of Earth’s tectonic plates. He was Project Scientist of the decade-long NASA Crustal Dynamics Project (CDP), an initiative that involved hundreds of individuals at numerous institutions. In this role he
set the tone for how space geodesy should work as a community. The CDP, which utilized very long baseline interferometry and satellite laser ranging, established the surprisingly strong agreement of instantaneous plate drift rates with those over geologic time scales.
Begining in the mid-1980s Dave turned his attention to the planets. He published a gravity field for Mars that was the first high-resolution spherical harmonic model of a planet other than Earth. He led the Clementine geophysics team that produced the first global topography and crustal thickness maps of the Moon. On the NEAR Shoemaker mission, Dave and colleagues produced the firstdetailed three-dimensional view of the shape of an asteroid (433 Eros), and from volume and mass came the first precise estimate of an asteroid’s mean density.
Dave was Principal Investigator of the Mars Orbiter Laser Altimeter (MOLA) that flew on Mars Global Surveyor and produced a global topographic model of Mars that was more accurate than Earth’s topographic model. MOLA established the planet’s flat northern hemisphere as the possible location of an ancient ocean, revealed pathways of past water transport, and yielded the present-day surface water inventory from the volumes of the polar caps. He measured the seasonal accumulation and ablation of Mars’ CO2 snow, as well as gravity field changes due to Mars’ CO2 cycle.
Dave is Principal Investigator of the Lunar Reconnaissance Orbiter’s Lunar Orbiter Laser Altimeter, the first multibeam planetary laser altimeter, which yielded the highest-resolution global topographic model for any planet. On NASA’s MESSENGER mission, Dave leads the gravity experiment that established bounds on internal structure as well as discovering mass concentrations (mascons) on Mercury. He also led experiments that made the longest two-way (24 Mkm) and one-way (87 Mkm) laser links.
Dave’s data sets have led to many scientific discoveries by others. His geodetic grids of the planets have allowed precise geolocation and coregistration of data from other experiments, increasing their value and aiding precision landing of Mars landers and rovers.
Dave Smith’s achievements in terrestrial geodesy or planetary geodesy alone would merit the Whitten Medal; for the combined contributions the case is extraordinary.
–Roger J. Phillips, Southwest Research Institute, Boulder, Colorado
Thank you friends and colleagues for nominating me for this honor. It is humbling to look at the list of previous recipients of the Whitten medal, many of whom I have known well, and realize the array of contributions they have made to this field.
Occasionally, being in the right place at the right time is an essential component for being considered successful in one’s chosen career and this, I feel, has been true for me. When I moved the United States after completing my education at the Universities of Durham and London in England, the discussion of plate tectonics was in full swing. The concept was no longer in doubt but global-scale observations of the kinematics of plate motions was needed to show that it was also a major factor in the cause of today’s earthquakes, and possibly, changes in the Earth’s rotation.
At the same time the development of lasers and their application to measuring large distances was a growing technology and as a result I moved my interest and emphasis from theoretical problems as a mathematician to the acquisition of precise observations to address the broad topic of Earth dynamics. This was a time when space agencies were beginning to appreciate the importance of knowing locations on the planet and I was fortunate to be in the right place and time to be involved in the application of this new field of space geodesy. This was a long-term interest and activity of mine and was the dominant topic of my first 15 plus years in the U.S.
In the early eighties, Bill Kaula, the second recipient of the Whitten medal, said to me it was “about time someone applied those ideas of space geodesy to Mars.” Bill had been at the Goddard Space Flight Center early in his career before moving to UCLA, and I had effectively taken his position at Goddard a number of years later. Again, I was in the right place at the right time in the mid-eighties because the U.S. had just decided it was time to return to Mars. Being selected as an investigator for topography and gravity on the first U.S. space mission to Mars in almost 20 years moved me to planetary geodesy and laser altimetry, and it is where I have been ever since.
This was a great time for many of us as the exploration of the Moon and Mercury were about to begin with the leadership of colleagues and friends, including Maria Zuber with whom I have worked for 25 years and who played such an important role in getting us back to the Moon, Sean Solomon who led us to Mercury and a new view of the inner-most planet, and to Roger Phillips who brought Mars into focus with his thoughts and ideas about the Martian poles and crust. It is a real honor to be awarded the Whitten medal, to have had so much fun, and to have worked with so many outstanding colleagues.
–David E. Smith, MIT, Cambridge, Massachusetts