James G. Williams

51 years of experience working on Lunar Laser Ranging theory, modeling and data analysis. LLR investigations include lunar science, lunar and terrestrial geophysics and geodesy, plus gravitational physics. Dynamics of the Earth-Moon system is a specialty including orbit and orientation of both bodies. Contributions made to solar system dynamics, evolution, origin, and early VLBI.

  • B.S., Astronomy, California Institute of Technology (1963)
  • Ph.D., Planetary and Space Physics, University of California at Los Angeles (1969)

Research Interests: 
  • Lunar dynamics, evolution, and geophysics
  • Lunar Laser Ranging theory, modeling and data analysis for lunar and terrestrial science, ephemerides, and gravitational physics
  • Orbital and rotational dynamics of solar system bodies

Professional Experience: 
  • 1969-present:  JPL, Solar System Dynamics, Evolution, Lunar Laser Ranging & VLBI

  • 1963-1968:  North American Aviation, Satellite Tracking

Selected Awards: 
  • Asteroid Named 2335 James
  • 1976, 2002 -- NASA’s Exceptional Scientific Achievement Medal
  • 2005-2006 -- Brouwer Award, AAS Division on Dynamical Astronomy
  • 2012 -- GRAIL Science Team, NASA
  • 2015 -- Edward Stone award, JPL

Selected Publications: 
  1. Efroimsky, M., and Williams, J. G. (2009) Tidal torques. A critical review of some techniques, Celestial Mechanics and Dynamical Astronomy, 104, 257-289, doi:10.1007/s10569-009-9204-7.
  2. Williams, J. G., Turyshev, S. G., and Boggs, D. H., (2009) Lunar Laser Ranging Tests of the Equivalence Principle with the Earth and Moon, International Journal of Modern Physics D, 18 (7), 1129-1175, doi:10.1142/S021827180901500X.
  3. Williams, J. G. (2007) A Scheme for Lunar Inner Core Detection, Geophys. Res. Lett. 34, L03202, doi:10.1029/2006GL028185
  4. Williams, J. G., Turyshev, S. G., Boggs, D. H., and Ratcliff, J. T. (2006) Lunar Laser Ranging Science: Gravitational Physics and Lunar Interior and Geodesy, in Space Research 37, Issue 1, The Moon and Near-Earth Objects, 67-71, doi: 10.1016/j.asr.2005.05.13. arXiv:gr-qc412049
  5. Williams, J. G., Turyshev, S. G., and Boggs, D. H. (2004) Progress in lunar laser ranging tests of relativistic gravity, Phys. Rev. Lett. 93, 261101, doi:10.1103/PhysRevLett.93.261101. arXiv:gr-qc411113
  6. Khan, A., Mosegaard, K., Williams, J. G., and Lognonne, P. (2004) Does the Moon possess a molten core? — Probing the deep lunar interior using results from LLR and Lunar Prospector, J. Geophys. Res. 109 (E9), E09007, doi:10.1029/2004JE002294
  7. Turyshev, S. G., Williams, J. G., Nordtvedt Jr., K., Shao, M., Murphy Jr., T. W. (2004) 35 Years of Testing Relativistic Gravity: Where do we go from here?, in 302.WE-Heraeus-Seminar: Astrophysics, Clocks and Fundamental Constants, Springer Verlag, Lect. Notes Phys. 648, 311-330. gr-qc311039
  8. Williams, J. G., Turyshev, S. G., and Murphy Jr., T. W. (2004) Improving LLR Tests of Gravitational Theory, International J. of Modern Phys. D 13 (No. 3), 567-582. http://www.worldscinet.com/ijmpd/13/1303/S0218271804004682.html
  9. Williams, J. G., and Dickey, J. O. (2003) Lunar Geophysics, Geodesy, and Dynamics, Proceedings of 13th International Workshop on Laser Ranging, eds. R. Noomen, S. Klosko, C. Noll, and M. Pearlman, NASA/CP-2003-212248, pp. 75-86. http://cddisa.gsfc.nasa.gov/lw13/lw_proceedings.html
  10. Williams, J. G., Boggs, D. H., Yoder, C. F., Ratcliff, J. T., and Dickey, J. O. (2001) Lunar rotational dissipation in solid body and molten core, J. Geophys. Res., 106, 27933-27968
  11. Wu, X. Bar-Sever, Y. E., Folkner, W. M., Williams, J. G., and Zumberge, J. F. (2001) Probing Europa's hidden ocean from tidal effects on orbital dynamics, Geophys. Res. Lett. 28, 2245-2248
  12. Wu, X. Bar-Sever, Y. E., Folkner, W. M., Williams, J. G., and Zumberge, J. F. (2001) Europa's tides and possible hidden liquid ocean -- With new analyses on different orbit configurations and non-global ocean basins, J. Geodetic Soc. Japan 47, 501-507
  13. Anderson, J. D., and Williams, J. G. (2001) Long-Range Tests of the Equivalence Principle, Classical and Quantum Gravity 18, 2447-2456
  14. Konopliv, A. S., Binder, A. B., Hood, L. L., Kucinskas, A. B., Sjogren, W. L., and Williams, J. G. (1998) Improved gravity field of the Moon from Lunar Prospector, Science 281, 1476-1480
  15. Malhotra, R., and Williams, J. G. (1997) Pluto's heliocentric orbit, in Pluto and Charon, eds. S. A. Stern and D. J. Tholen, The Univ. Ariz. Press, Tucson, AZ, 127-157
  16. Newhall, X X, and Williams, J. G. (1997) Estimation of the Lunar Physical Librations, Celestial Mech. and Dyn. Astron. 66, 21-30
  17. Hartmann, T., Williams, J. G., and Soffel, M. (1996) Errors in the J3 part of nutation series, Astron. J. 111, 1400-1404


Publications Summary

  • 83 Papers in Refereed Journals
  • 14 Invited Reviews and Refereed Papers in Books
  • 47 Proceedings and other Book Contributions
James G. Williams
4800 Oak Grove Dr.
Pasadena, CA 91109
Phone: 818.354.6466
Fax Number: 818.393.4965