Robert “Bob” Carlson died peacefully in his sleep in Reno, Nevada, surrounded by family, after a months-long battle with cancer.

Carlson was born in Waseca, Minnesota, graduated from Cal Poly San Luis Obispo in 1963, and received his Ph.D. in physics from the University of Southern California in 1970. He spent most of his career (1978–2016) at the Jet Propulsion Laboratory in Pasadena, California.

As Principal Investigator of the Galileo Near Infrared Mapping Spectrometer (NIMS), Carlson was also the greatest skeptic of the results. Among many firsts by Carlson and the NIMS team, the discovery of hydrogen peroxide and a radiolytic sulfur cycle on Europa have transformed our understanding of the potential habitability of that world, and have helped set the stage for future exploration.

As an AGU Fellow and Editor-in-Chief for the Journal of Geophysical Research–Planets, Carlson worked hard to see the best in every manuscript. In the lab, he was meticulous and diligent, enjoying every opportunity to solve a new planetary puzzle. He was a brilliant scientist, as well as an amazing mentor, friend, husband, father, and grandfather. Those who knew him will recall fond memories of his soft, but detailed approach to any problem — always gracious and insightful.

— Text courtesy of the Division for Planetary Sciences of the American Astronomical Society