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David O'Brien

2011 Research Report


O'Brien has continued his work on the collisional and dynamical evolution of the main-belt and near-Earth asteroid populations.  He is currently collaborating with a group, including Fred Ciesla and his postdoc Thomas Davison, to couple models of the dynamical and collisional environment in the primordial asteroid belt to hydrocode models of impacts between planetesimals, in order to estimate the degree of shock heating that can occur in those bodies.  That work may provide an explanation for the early thermal alteration observed in numerous meteorite classes.  He is working on several other projects that fall under this area of research as well, including studies of the origin and collisional evolution of the Trojan asteroids (with Alessandro Morbidelli), modeling how the asteroid size distribution can evolve differently in different regions of the asteroid belt (with Patrick Michel), and exploring how variations in collision velocity in different parts of the asteroid belt may affect the histories of different meteorite parent bodies.

He has also been selected as a participating scientist for NASA's Dawn mission, and is working to help put Vesta's evolution and cratering history in the context of the evolution of the asteroid belt as a whole.  A primary focus of his work with the Dawn team is to develop a self-consistent cratering chronology for Vesta based on models of the dynamical evolution of the asteroid belt and early Solar System, and to calibrate that chronology against the cratering record of Vesta and the impact history recorded in the HED meteorites.  In addition, he is using the shape models of Bob Gaskell to make sets of color and shaded-relief topography quadrangles to be used by the mapping teams, and using raytracing software tools to help visualize Dawn data by combining imaging data with topography to generate perspective views and animations of different regions and surface features.

The other major focus of his work is the numerical simulation of terrestrial planet accretion in our Solar System as well as in systems around other stars.  He is working with Alessandro Morbidelli, Kevin Walsh, Sean Raymond and Avi Mandell to reconcile multiple lines of chemical and dynamical evidence for the formation of terrestrial planets in our Solar System.  Recent work has explored a new paradigm for the formation of the terrestrial planets, in which the inward-then-outward migration of Jupiter early in the history of the Solar System truncates the disk in the terrestrial planet zone and scatters material into the asteroid belt from a large range of semimajor axis.  This helps to explain both the small mass of Mars (which has been difficult to reproduce in past simulations), as well as the diversity of bodies found in the asteroid belt.  A paper on this work was published in Nature.

He is working with postdoc Jade Bond to couple numerical simulations of terrestrial planet formation in the Solar System and other planetary systems with models of the chemical evolution and condensation of solids in protoplanetary nebulae.  This work is currently being expanded to include more realistic simulations with larger numbers of particles, gas drag, and the effects of giant planet migration, and is being applied to planets around low-mass stars.

Publications 

Papers

D. P. O'Brien and M. V. Sykes (2011).  The Origin and Evolution of the Asteroid Belt--Implications for Vesta and Ceres.  Space Science Reviews 163, pp. 41-61.

K. Righter and D. P. O'Brien (2011).  Terrestrial Planet Formation.  Proc. Natl. Acad. Sci. 108, pp. 19165-19170.

K. J. Walsh, A. Morbidelli, S. N. Raymond, D. P. O'Brien and A. M. Mandell (2011).  A low Mass for Mars from Jupiter's Early Gas-Driven Migration.  Nature 475, pp. 206-209.

J. I. Lunine, D. P. O'Brien, S. N. Raymond, A. Morbidelli, T. Quinn and A. L. Graps (2011).  Dynamical Models of Terrestrial Planet Formation.  Advanced Science Letters 4, pp. 325-338.

Abstracts

D. P. O'Brien, M. V. Sykes and P. Tricarico (2011). Collision Probabilities and Impact Velocity Distributions for Vesta and Ceres.  LPSC 42, abstract no. 2665.

J. C. Bond, D. P. O'Brien and S. N. Raymond (2011).  The Diversity of Extrasolar Terrestrial Planets: Adding Migration into the mix.  Joint DPS/EPSC Meeting, Nantes, France, abstract no. 160.

A. Morbidelli, K. Walsh, S. Raymond, D. P. O'Brien and A. Mandell (2011).  The Grand Tack Scenario: Reconstructing The Migration History Of Jupiter And Saturn In The Disk Of Gas.  Extreme Solar Systems II Conference, Moran, WY.

K. J. Walsh, A. Morbidelli, S. N. Raymond, D. P. O'Brien and A. M. Mandell (2011). The Asteroid Belt and Mars' Small Mass Explained by Large-Scale Gas-Driven Migration of Jupiter.  Joint DPS/EPSC Meeting, Nantes, France, abstract no. 1583.

D. C. Rubie, D. P. O'Brien, F. Nimmo, A. Morbidelli, D. J. Frost and H. Palme (2011).  Heterogeneous Accretion of the Terrestrial Planets. LPSC 42, abstract no. 1061.

W. K. Hartmann, C. A. Goodrich, D. P. O'Brien, P. Michel, S. J. Weidenschilling and M. V. Sykes (2011).  Breakup and Reassembly of the Ureilite Parent Body, Formation of 2008 TC3/Almahata Sitta, and Delivery of Ureilites to Earth.  LPSC 42, abstract no. 1360.

K. J. Walsh, A. Morbidelli, S. N. Raymond, D. P. O'Brien and A. M. Mandel (2011). The Asteroid Belt and Mars' Small Mass Explained by Large-Scale Gas-Driven Migration of Jupiter.  LPSC 42, abstract no. 2585.

T. M. Davison, F. J. Ciesla, G. S. Collins and D. P. O'Brien (2011).  The Role of Impacts in the Thermal Evolution of Planetesimals.  LPSC 42, abstract no. 2254.

T. M. Davison, G. S. Collins, F. J. Ciesla and D. P. O'Brien (2011).  The Energy Budget of Planetesimal Collisions: A Quantitative Analysis.  LPSC 42, abstract no. 2530.

D. C. Rubie, D. J. Frost, D. P. O'Brien, F. Nimmo, A. Morbidelli and H. Palme (2011).  Accretion and Differentiation of the Terrestrial Planets. Goldschmidt Conference, Prague, Czech Republic.

S. N. Raymond, K. J. Walsh, A. Morbidelli, D. P. O'Brien and A. M. Mandell (2011).  How Jupiter's Two-Phase Gas-Driven Migration Shaped the Inner Solar System.  Goldschmidt Conference, Prague, Czech Republic.

C. A. Dwyer, F. Nimmo, E. Asphaug, D. P. O'Brien and J. E. Chambers (2011). Erosion during accretion: Consequences for planetary iron-silicate ratios and tungsten isotope anomalies.  Gordon Research Conference on Origins Of Solar Systems, Mt. Holyoke College, South Hadley, MA.

C. A. Dwyer, F. Nimmo, E. Asphaug, D. P. O'Brien and J. E. Chambers (2011). Erosion during accretion: Consequences for planetary iron-silicate ratios and tungsten isotope anomalies.  AGU Fall Meeting, San Francisco, CA, abstract P11A-1586.

L. A. McFadden, M. Sykes, S. Joy, P. Tricarico, D. P. O'Brien, J.-Y. Li, M. Mutchler, N. Memarsadeghi, H. Safavi, P. Gutierrez-Marques, A. Nathues, S. Mottola, H. Sierks, S. Schroder, C. Polansky, R. Jacobson, C. T. Russell, C. A. Raymond, M. Rayman, S. Weinstein-Weiss and E. Palmer.  Does Vesta Have Moons?  74th Meteoritical Society Meeting, Grenwich, UK.

R. Jaumann and the Dawn Geosciences Team (2011).  Mapping Vesta: First Results from Dawn's Survey Orbit.  Joint DPS/EPSC Meeting, Nantes, France, abstract no. 437.

G. Neukum, P. Schenk, N. Schmedemann, G. Michael, R. Jaumann, J. Scully, C. T. Russell, D. P. O'Brien, H. Hiesinger, A. Nathues, R. Wagner and S. Marchi (2011).  Chronology and Cratering at Vesta: First Results from Dawn's Survey Orbit.  Joint DPS/EPSC Meeting, Nantes, France, abstract no. 501.

P. Schenk, G. Neukum, N. Schmedemann, D. P. O'Brien, H. Hiesinger, R. Jaumann, B. E. Schmidt, S. Marchi, J.-B. Vincent and R. Wagner (2011).  Impact Crater Morphology and Chronology of Vesta.  Geological Society of America Meeting, Minneapolis, MN, abstract no. 239-8.

J. C. Carter-Bond and D. P. O'Brien (2011).  The Compositional Diversity of Extrasolar Terrestrial Planets.  AGU Fall Meeting, San Francisco, CA, abstract P23F-04.

P. Schenk, R. Jaumann, C. M. Pieters, G. Neukum, N. Schmedemann, R. A. Yingst, D. A. Williams, W. B. Garry, D. L. Buczkowski, T. B. McCord, M. V. Sykes, D. P. O'Brien, D. T. Blewett, S. Asmar, A. Ermakov, R. W. Gaskell, C. A. Raymond, C. Polanskey, S. Marchi, S. Mottola, T. H. Prettyman, T. Roatsch, F. Preusker, A. Nathues, M. C. DeSanctis, H. Y. McSween and C. T. Russell (2011).  The South Polar Structure on Vesta from Dawn: Using Geologic, Topographic and Compositional Mapping and Planetary Analogs to Test Origin Models.  AGU Fall Meeting, San Francisco, CA, abstract U21B-03.

L. A. McFadden, M. V. Sykes, P. Tricarico, U. Carsenty, P. Gutierrez-Marques, R. A. Jacobson, S. P. Joy, H. U. Keller, J.-Y. Li, B. McLean, N. Memarsadeghi, S. Mottola, M. Mutchler, A. Nathues, D. P. O'Brien, E. E. Palmer, C. Polanskey, H. Sierks, M. D. Rayman, C. A. Raymond, C. T. Russell, S. Schroeder, D. Skillman and S. Weinstein-Weiss (2011).  Does Vesta Have Moons?: Dawn's Search for Satellites.  AGU Fall Meeting, San Francisco, CA, abstract U31A-0005.

R. Jaumann, C. M. Pieters, C. T. Russell, C. A. Raymond, R. A. Yingst, D. A. Williams, P. Schenk, G. Neukum, S. Mottola, D. L. Buczkowski, D. P. O'Brien, W. B. Garry, D. T. Blewett, B. W. Denevi, T. Roatsch, F. Preusker, A. Nathues, H. Sierks, M. V. Sykes, M. C. DeSanctis, H. Y. McSween, H. U. Keller and S. Marchi (2011).  Mapping Vesta: A Geological Overview.  AGU Fall Meeting, San Francisco, CA, abstract U21B-02.

R. Jaumann, R. A. Yingst, P. Schenk, N. Schmedemann, D. A. Williams, C. M. Pieters, D. L. Buczkowski, K. Stephan, T. Roatsch, F. Preusker, F. Scholten, G. Neukum, D. P. O'Brien, S. C. Mest, K. Krohn, S. Marchi, C. T. Russell, C. A. Raymond and M. C. DeSanctis (2011).  Mapping Vesta South Polar Quadrangle V-15SP: A Complex Geological Structure Dominates Vesta.  AGU Fall Meeting, San Francisco, CA, abstract U31A-0023.

Research Year: 
2011

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