| 1985-87 | Engineering Co-op, Reactor Plant Planning Yard, Newport News Shipbuilding |
| 1987-89 | Teaching Assistant, Physics Department, The University of Chicago |
| 1989-92 | Research Assistant, Department of Astronomy and Astrophysics, The University of Chicago |
| 1992-94 | Postdoctoral Fellow, Advanced Study Program, National Center for Atmospheric Research |
| 1994-95 | Visiting Scientist, National Center for Atmospheric Research |
| 1995-96 | Research Associate, Joint Institute for Laboratory Astrophysics & Laboratory for Atmospheric and Space Physics, Univ. of Colorado |
| 1997-01 | Research Scientist, NorthWest Research Associates |
| 1998- | Adjunct Faculty, Department of Applied Mathematics, Univ. of Colorado |
| 2001- | Senior Research Scientist, NorthWest Research Associates |