Sol Alan Stern (born November 22, 1957) is an American engineer and planetary scientist. He is the principal investigator of the New Horizons mission to Pluto and the Chief Scientist at Moon Express.
Stern has been involved in 24 suborbital, orbital, and planetary space missions, including eight for which he was the mission principal investigator. One of his projects was the Southwest Ultraviolet Imaging System, an instrument which flew on two space shuttle missions, STS-85 in 1997 and STS-93 in 1999.
Stern has also developed eight scientific instruments for planetary and near-space research missions and has been a guest observer on numerous NASA satellite observatories, including the International Ultraviolet Explorer, the Hubble Space Telescope, the International Infrared Observer and the Extreme Ultraviolet Observer. Stern was executive director of the Southwest Research Institute's Space Science and Engineering Division until becoming Associate Administrator of NASA's Science Mission Directorate in 2007. He resigned from that position after nearly a year. In early 2009 Stern's name was mentioned as a potential contender for the position of NASA administrator under President Obama's administration. Stern stated, however, that he was not interested in the position then.