--Ames Research Center
Chief of the Space Science Division
Director of Space
Senior Scientist
Chief Scientist, Ames Planetary Defense research team
Chair, NASA Planetary Astronomy Committee
Chair, NASA Spaceguard Working Group
Chair, NASA Astrobiology Roadmap Working Group
Founding member of the multidisciplinary science of astrobiology
Drafted Original Charter and Coorperative Agreement notice for the competitive selection of the Institute teams for the NASA Astrobiology Institute
Leading role in defining the asteroid impact hazard, including chairing the congressionally mandated NASA Spaceguard Committee in 1991-92
Founding Director of the NASA Lunar Science Institute
Senior Scientist at SSERVI, NLSI successor Institute
-- NASA Headquarters
Galileo Program Scientist and Interdisciplinary Scientist
