Geochemistry, Cosmochemistry, Nuclear Chemistry
A major theme of the research of the EFI geo-cosmochemists has been the study of elemental and isotopic abundances of extraterrestrial materials. An outstanding accomplishment of this work was the discovery of interstellar dust particles in meteorites, which pre-date the formation of the solar system and carry intact records of several processes of stellar nucleosynthesis. This discovery was made by E. Anders (now retired), Roy Lewis and their co-workers. Isotopic measurements on individual micrometer-sized grains are made using Resonant Ionization Mass Spectrometry in a collaboration with Michael Pellin at Argonne National Laboratory. These measurements provide direct analyses of the products of nuclear reactions in stars, which produce almost all of the chemical elements. Such new methods are essential for continued meteorite studies, and for the next generation of cosmochemical experiments which involve the study of returned samples of comets and asteroids.
Robert N. Clayton and his group have successfully analyzed isotope tracers in meteorites from Mars in order to characterize the Martian hydrosphere. These meteorites are thought to have been ejected from the Martian surface by an asteroid impact. They contain evidence that water was once present on the surface of Mars. In a broader context, these results are part of a study of the origin and evolution of the solar system through measurements of variations in the abundance of the isotopes of several elements in rocks and minerals from Earth, Moon, and meteorites. Lawrence Grossman studies the minerals in and trace element and isotopic compositions of primitive meteorites in order to learn about physical and chemical processes that occurred in the solar nebular cloud prior to the formation of planets.
Thanasis Economou has designed and build apparatus for in situ chemical analysis of planetary and asteroidal surfaces. His APXS instrument was part of the Pathfinder mission to Mars, which successfully analyzed rocks and soils on the Red Planet in 1997.