Richard M. Goldstein, a trailblazer in planetary exploration who used ground-based radars to map planets with techniques that scientists now use to measure geographical changes on Earth, including melting glaciers, died on June 22 at his home in La Canada Flintridge, CA. He was 97.

In the early 1960s, while a graduate student in electrical engineering at the California Institute of Technology, he proposed as his thesis project to try to detect echoes from Venus, using the Goldstone Solar System Radar, which had been newly developed. If successful, scientists would learn the distance from Earth to Venus. On March 10, 1961, technicians pointed the new radar at Venus. Six and a half minutes later, signals from the planet returned. He bounced signals off Mercury, Mars and Saturn’s rings, all making it possible to do accurate spacecraft navigation within the solar system.

Later, he adapted his radar algorithms for use with aircraft and satellites, which have mapped melting glaciers, the movement of tectonic plates, and other changes to the Earth’s surface.