is the Interplanetary Network Directorate Scientist at the Jet Propulsion Laboratory, California Institute of Technology. He received his Ph.D. from Cornell University, was a National Research Council Research Associate at the U.S. Naval Research Laboratory, and was a Radio Astronomer on the staff of the Naval Research Laboratory, before joining JPL. He is the Project Scientist for the Sun Radio Interferometer Space Experiment (SunRISE) mission, and he has served as Project Scientist for the Square Kilometre Array (SKA); the Deputy Director of the Lunar University Network for Astrophysics Research (LUNAR), part of the NASA Lunar Science Institute; and the Project Scientist for the U.S. Virtual Astronomical Observatory. He observes routinely with the world's premier ground-based radio telescopes, including the Jansky Very Large Array, the Very Long Baseline Array, and the Green Bank Telescope.