He spent one year, from 1964 to 1965, as a NASA Trainee at Stanford University, and was appointed Assistant Professor at the University of Iowa in 1965 with subsequent promotions to Associate Professor and to Professor in 1968 and 1972. He regularly teaches both undergraduate and graduate courses in physics and astronomy. Among the awards he has attained, he received the M. L. Huit Faculty Award for outstanding service and dedication to students at the University of Iowa in 1990 and the Iowa Board of Regents Award for Faculty Excellence in 1994.
Don specializes in the study of space plasma physics and has participated in over 40 spacecraft projects, most notably the Voyager 1 and 2 flights to the outer planets, the Galileo mission to Jupiter, and the Cassini mission to Saturn. He is the author/co-author of over 650 scientific publications, primarily in the area of magnetospheric radio and plasma wave research. Don has received numerous awards for his research. In 1998 he was elected a member of the National Academy of Sciences, and in 2004 he was elected a Fellow of the American Academy of Arts and Sciences