Sean C. Solomon
Director Emeritus

Sean Solomon

Research Interests

Planetary geology and geophysics; seismology; marine geophysics; tectonics; geodynamics


B.S., Geophysics, California Institute of Technology, 1966 Ph.D., Geophysics, Massachusetts Institute of Technology, 1971

Contact & Links

  • (202) 478-8820 | fax: (202) 478-8821
  • ssolomon at
  • Department of Terrestrial Magnetism
    Carnegie Institution of Washington
    5241 Broad Branch Road, NW
    Washington, DC 20015-1305
  • curriculum vitae
  • Personal Website


Sean Solomon's research focuses on planetary geology and geophysics, seismology, marine geophysics, and geodynamics. His experience ranges from oceanographic expeditions on Earth to spacecraft missions to the Moon, Venus, Mars, and Mercury.

As Principal Investigator for the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission, Solomon heads a multiinstitutional consortium of scientists and engineers who operate the small, efficient MESSENGER spacecraft, which launched in 2004 and successfully entered into orbit around Mercury at 9:10 p.m. EDT on 17 March 2011. Continuous global mapping began on 4 April as MESSENGER entered its yearlong science campaign to understand the innermost planet.

To date, the only craft sent to Mercury was Mariner 10 in the 1970s, and it imaged less than half of the planet. With a suite of seven miniaturized instruments, MESSENGER is now addressing questions that are key to understanding terrestrial planet evolution. Solomon's particular interests are to learn more about Mercury's bulk composition and what that tells us about planet formation in general; to investigate its volcanic, tectonic, and internal evolution; and to understand how the planet's magnetic field originated and determine whether there is a liquid outer core. Mariner 10 discovered that Mercury has a weak magnetic field, which may arise from an electromagnetic dynamo created in a liquid metallic outer core. Because the planet is small, scientists had thought that the core had cooled and solidified long ago. MESSENGER is investigating this question as well as the nature of the planet's thin atmosphere and the composition of the permanently shadowed polar deposits.

For 10 years Solomon served as Principal Investigator for Carnegie's research as part of the NASA Astrobiology Institute (NAI). Astrobiology is an interdisciplinary approach to understanding the origin of life on Earth and its potential for existing elsewhere. Scientists from DTM and the Geophysical Laboratory are addressing the pathways of carbon and other ingredients for biology from elements and compounds in the interstellar medium to circumstellar disks and planetary habitats, to prebiotic chemistry under a variety of conditions, to early organic processes on Earth, to the search for biomarkers on Earth and other planetary bodies.

Solomon is also a team member on a variety of other projects including the Gravity Recovery and Interior Laboratory (GRAIL) mission and the Plume-Lithosphere Undersea Melt Experiment (PLUME). The dual-spacecraft GRAIL mission, which launched on 13 September 2011, will determine the gravity field of the Moon in unprecedented detail. PLUME was a combined land and ocean-bottom seismic experiment to image the mantle beneath the Hawaiian hotspot, and Solomon led the land section of this project; the project is now in the data analysis phase.

Since July 2012, Solomon has been the Director of Lamont-Doherty Earth Observatory, Associate Director for Earth Systems Science at the Earth Institute, and the William B. Ransford Professor of Earth and Planetary Science at Columbia University.