Best known for the identification of silicates being ejected from red giant stars, appearing in the interstellar medium, and present in comets.  Additionally, he developed the rationale for building telescopes with lightweight mirrors in thermal equilibrium with the air.

He also helped initiative designs of telescopes and interferometers for observing terrestrial planets around other stars and is the principal investigatorI for the Tucson node of NASA's Astrobiology Institute, LAPLACE.