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.