Dr Ed Stone, former director of JPL, Voyager project scientist, dies at 88

A legacy of scientific discovery, inspiration and engagement

Obit Edward C Stone, the project scientist for NASA's Voyager mission from 1972 to 2022, has died.

Voyager Project Scientist Ed Stone on stage for New Horizons Event

Dr. Ed Stone speaks on a panel at a New Horizons event in 2014 – credit: NASA/Aubrey Gemignani

Born in Knoxville, Iowa, in 1936, Stone studied physics at Burlington Junior College. He went on to graduate school at the University of Chicago. In his autobiography, Stone recalled: "In 1957, as I drove to the University of Chicago for the Fall term of physics classes, I remember seeing a newspaper headline announcing that Russia had launched a spacecraft into earth orbit.

"Sputnik 1 transmitted a radio signal as it circled Earth, marking the beginning of the Space Age and a new realm of human activity."

Stone soon joined a team building instruments to launch into space. He wrote, "My thesis experiment, a cosmic ray telescope, was launched into a polar orbit on Explorer 36. Though the data were limited, this was my first step in measuring cosmic rays from supernova explosions and solar energetic particles produced by solar eruptions."

Stone wrote that he had been the principal investigator or co-investigator on 15 NASA spacecraft. NASA noted, "He was one of the few scientists involved with both the mission that has come closest to the Sun (NASA's Parker Solar Probe) and the one that has traveled farthest from it (Voyager)."

Along with a long and varied career that included stints as the director of NASA's Jet Propulsion Laboratory (JPL), the chair of the Division of Physics, Mathematics and Astronomy at Caltech, and the title of Caltech's David Morrisroe Professor of Physics, Emeritus, one of Stone's lasting legacies will be the Voyager mission.

Stone was the Voyager Project Scientist and was responsible for coordinating 11 teams of scientists. The project's first science steering group meeting was held at JPL in December 1972, when Voyager was still called Mariner Jupiter Saturn (MJS.) In 1977, the Voyagers launched, taking advantage of a rare alignment of the planets that enabled the spacecraft to swing past Jupiter and Saturn and Voyager 2 to go on to Uranus and Neptune.

Former Voyager scientist Garry Hunt paid tribute to Stone in an email to The Register: "Ed was a brilliant scientist and inspirational leader, an outstanding leader of the everlasting Voyager mission and a wonderful friend and colleague for more than 50 years.

"Every one of us involved in the Voyager mission has so much to thank Ed Stone for."

Two years after Voyager 2's 1989 flyby of Neptune, Stone became JPL Director, serving from 1991 to 2001. During his tenure, JPL's missions included the Mars Sojourner Rover, the arrival at Jupiter of the Galileo probe, and the launch of the Cassini-Huygens mission.

Before his time at JPL, Stone oversaw the establishment of the Laser Interferometer Gravitational-Wave Observatory (LIGO). After his retirement as JPL director, Stone became the founding executive director for the Thirty Meter Telescope (TMT) International Observatory.

Stone won the Shaw Prize for Astronomy in 2019 for his leadership of the Voyager project.

Caltech President Thomas F Rosenbaum, the Sonja and William Davidow Presidential Chair and Professor of Physics said: "A great scientist, a formidable leader, and a gifted expositor of discovery, Ed will be missed sorely by all who he inspired at Caltech and in the astronomy community at large."

Stone leaves children, grandchildren, and a legacy of scientific discovery and inspiration behind him.

We'll leave the last words to Garry Hunt: "I learned a great deal from my long friendship and working relationship with Ed Stone.

"He will be missed greatly," he told us. ®

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