PASADENA, Calif. (AP) — William H. Pickering, who as director of the Jet Propulsion Laboratory at the dawn of the space age oversaw the launch of the first U.S. satellite, has died, lab officials said Tuesday. He was 93.

Pickering, who twice appeared on the cover of Time magazine, died of pneumonia Monday at his home in suburban La Canada Flintridge, JPL said.

"Dr. Pickering was one of the titans of our nation's space program," JPL director Charles Elachi said. "It was his leadership that took America into space and opened up the moon and planets to the world."

Pickering headed JPL, for decades the center for the robotic exploration of the solar system, from 1954 to 1976.