Mustard was initially fascinated with the work of marine biologists such as
Jacques Cousteau, but he chose to study in earth sciences. He earned his B.Sc. in geology from the
University of British Columbia in 1983, and continued his studies in the Department of Geological Sciences at Brown University obtaining an M.Sc. in 1986 and a Ph.D. in 1990. He was a founding member of the Environmental Change Initiative at Brown University in 2000, that has since become the Institute at Brown for Environment and Society (IBES). He is currently Co-Director along with
Barbara Sherwood Lollar (University of Toronto) of the Earth 4D program of the Canadian Institute for Advanced Research (CIFAR) and the Deputy Principal Investigator of the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the NASA Mars Reconnaissance Orbiter == Mission involvement ==