Pickering, known affectionately as "Mr. JPL," served as director from 1954 to 1976. He was an original "Rocket Man," and one of few public figures to appear twice on the cover of Time magazine.

"Dr. Pickering brought a vision and passion to space exploration that was remarkable," said Dr. Ed Weiler, NASA's Associate Administrator for Space Science. "His pioneering work is the very foundation we have built upon to explore our solar system and beyond," he said.

Pickering led the successful effort to place the first U.S. satellite, Explorer 1, into Earth orbit. Following the success of Explorer 1, Pickering was instrumental in leading a new era of robotic space exploration, including the first missions to the moon and the planets.

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

Pickering started at JPL in 1944, when the laboratory was developing missile systems for the U.S. Army. He organized the electronics efforts at JPL to support guided missile research and development, becoming project manager for Corporal, the first operational missile JPL developed. It was not a simple project. In an interview in 1994, Pickering joked about the trials and tribulations of testing the early guidance systems.

"For the 100th Corporal that we tested, I pushed the [launch] button, and the darn thing went east instead of north. I never pushed the button again," he recalled.Eventually, under Pickering's direction, JPL developed the successful Sergeant solid-propellant missile.

In 1954, Pickering was named director of JPL, and he soon had his hands full with the space race. In November 1957, following the first Soviet Sputnik launch, JPL and the Army Ballistic Missile Agency were given the assignment to place the first U.S. satellite into orbit. Pickering directed the JPL effort, which, in just 83 days, provided the satellite, telecommunications, and the upper rocket stages that lofted Explorer 1 into orbit on January 31, 1958. It was considered one of Pickering's greatest achievements and laid the groundwork for future robotic exploration of the moon and planets.

In 1958 JPL, managed by the California Institute of Technology (Caltech), was transferred from the Army to the newly created National Aeronautics and Space Administration. In succeeding years, JPL conducted an intensive series of space probes including Ranger and Surveyor missions to the moon, and the Mariner missions to Earth's neighboring planets.

On December 14, 1962, the Mariner 2 spacecraft successfully completed a flyby of Venus, culminating a 109-day journey of more than 290 million kilometers (180 million miles). It was humankind's first penetration to the vicinity of another planet. On July 14, 1965, following a 228-day journey of more than 525 million kilometers (325 million miles) by Mariner 4, Pickering's team obtained the first close-up pictures of Mars. Four more Mariner missions reached Venus and Mars before Pickering retired from JPL in 1976 at age 66.

Pickering received numerous awards throughout his career, including NASA's Distinguished Service Medal. In 1975, he was awarded the National Medal of Science by President Gerald Ford, and in 1976 he was given honorary knighthood from the Queen of England. He also received awards from numerous science and engineering societies.

Pickering was born in Wellington, New Zealand in 1910. He came to the United States in 1929 to study at Caltech. Pickering was naturalized a U.S. citizen in 1941. He obtained his bachelor's and master's degrees in electrical engineering, and he received a Ph.D. in physics from Caltech before becoming a professor of electrical engineering there in 1946.

His widow, Inez Chapman Pickering, and daughter, Elizabeth Pickering Mezitt, survive him.