Dr. Jeffrey R. Johnson is a Principal Professional Scientist at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland. As a geologist and planetary scientist, his interests are in using visible/near-infrared, thermal infrared, and Raman spectroscopy and light scattering properties to understand the composition of planetary surfaces. His work includes studies of analog materials, dust coatings, and the spectral changes associated with high shock pressures in minerals and rocks. He participated in the Mars Pathfinder and Mars Polar Lander missions, and served as an Associate Principal Investigator and Participating Scientist (PS) on the Mars Exploration Rovers. He is currently a PS on the Mars Science Laboratory Curiosity rover mission, a Co-Investigator on the SuperCam and Mastcam-Z instruments on the Mars2020 Perseverance rover mission, and Co-Investigator on the Dragonfly mission to Titan. He also served as the Chair of the Mars Exploration Program Analysis Group (MEPAG) from 2016-2019 and was an Associate Editor for the journal Icarus from 2014-2020.