The Planetary Science Institute (PSI) is a 501(c)(3) non-profit research institute based in Tucson, Arizona, focusing on planetary science. As of 2018, its director is Dr. . Founded in 1972, PSI is involved in many NASA missions, the study of Mars, asteroids, comets, interplanetary dust, the formation of the Solar System, extrasolar planets, the origin of life, and other scientific topics. It actively participated in the Dawn mission, which explored Vesta between 2011 and 2012, and Ceres between 2015 and 2018. It managed the spacecraft's Gamma Ray and Neutron Detector, which mapped the surfaces of the two minor planets to determine how they were formed and evolved.