Pettengill began his career at the
MIT Lincoln Laboratory in 1954. Pettengill successfully completed a two-dimensional radar mapping of the Moon in 1960, a key step in the U.S. preparations for the
Apollo program, ensuring that the Apollo astronauts would not disappear under a meters-thick layer of dust. He was appointed Professor of Planetary Physics in the Department of Earth and Planetary Sciences at MIT in 1970. In the late 1960s and early 1970s, Pettengill led ground-based radar studies of the surface properties of all of the inner planets, including the Earth's (via a "triple-bounce" experiment: Moon-Earth-Moon). Pettengill also played a leading role in the first radar studies of an asteroid (Icarus, in 1968), a comet (Encke, in 1980), and moons of other planets (the Galilean satellites, starting in 1976). In all of this work, Pettengill made use of radar systems at
MIT's
Haystack Observatory and
Cornell's
Arecibo Observatory, systems whose development he had guided for astronomical applications. Also in the 1970s, he was involved in several unmanned missions to
Mars (including the Viking program). For over two decades, beginning in 1977, he concentrated most heavily on
Venus, this time utilizing radars aboard spacecraft, first the
Pioneer Venus orbiter and later,
Magellan. For many years, he pursued the idea for using a radar altimeter to map Venus and contributed key technical ideas. The results, in part, were detailed reflectivity and topographic maps of virtually the entire planet of Venus, providing geologists and geophysicists with lifetimes of work to understand the development of Venus' crust and the history of its interior. Many planetary scientists feel he was one of the individuals most responsible for our present knowledge of
Venus (aside from its atmosphere). His observations embraced Mercury, Venus, Mars, several asteroids and comets, the Galilean satellites of Jupiter and the rings of Saturn. ==Awards and honours==