Research Interests

My primary interest is the application of radar and radio interferometric techniques to fundamental scientific questions in astronomy, geophysics, and physics. Recent research includes estimating the Hubble constant based on VLBI and other observations of gravitational lens systems; studying the structure of the Earth using the Global Positioning System and VLBI; testing gravitational theories using radio and radar observations; and making VLBI astrometric measurements of pulsars, stars, galaxies, and quasars. I am also involved in pre-college science education. Recent activities include participation in developing elementary and secondary curriculum; producing video instructional material for teachers and public television; conducting summer institutes for in-service science teachers; and educating pre-service science teachers.

Membership Type


Election Year


Primary Section

Section 12: Astronomy

Secondary Section

Section 13: Physics