The Planetary Society remembers Ed Stone

Edward C. Stone, Caltech's David Morrisroe Professor of Physics, Emeritus, passed away on June 9 at the age of 88. Stone was a prominent figure in space physics and planetary astronomy, where he led numerous space missions and significantly advanced the field.

Stone is best known for his role as project scientist for NASA's twin Voyager spacecraft, a mission he guided for 50 years. Under his leadership, the Voyager project achieved monumental milestones, including the first encounter with extraterrestrial volcanism on Jupiter's moon Io in 1979, and the historic crossings of Voyager 1 and 2 into interstellar space in 2012 and 2018, respectively. His work exemplified the spirit of exploration and sense of wonder that was an inspiration to many.

In 1991, Stone became the director of the Jet Propulsion Laboratory (JPL), where he oversaw 21 missions and instruments, including the groundbreaking Mars Pathfinder lander and Sojourner Mars rover — the first wheeled vehicle to operate on another planet. After the mission, the Pathfinder lander — which carried the names of over 100,000 Planetary Society members on a microchip — was named the Sagan Memorial Station in honor of our co-founder Carl Sagan.

Beyond space missions, Stone's contributions extended to the establishment of the Laser-Interferometer Gravitational-wave Observatory (LIGO) during his time as chair of the Division of Physics, Mathematics, and Astronomy at Caltech. LIGO later achieved the first direct detection of gravitational waves, marking a new era in astrophysics.

Stone's influence was also felt in ground-based astronomy, where he played a key role in the construction of the W. M. Keck Observatory and the Thirty Meter Telescope (TMT). His leadership in these projects helped solidify their positions as some of the most productive astronomical observatories in the world.

Throughout his illustrious career, Stone received numerous accolades, including the National Medal of Science and the NASA Distinguished Public Service Medal. His work not only expanded our understanding of the Cosmos but also inspired future generations to explore and reach for new frontiers.

Dr. Stone was a cherished friend of The Planetary Society, and his legacy will continue to inspire us. We were fortunate to have him join us as a member early in our history and as a featured guest on several Planetary Radio episodes. The following are reflections and stories from leaders at The Planetary Society who had the privilege of working closely with him:

“I am saddened to hear this news of Ed Stone's passing, but also grateful to have crossed paths and shared some orbits of the Sun with such a preeminent, impactful, and kind planetary science colleague.

I first encountered Ed at JPL during the Voyager Uranus and Neptune flybys in the 1980s, when I was working as a student for a member of the Voyager Imaging Team. I was immediately impressed by his calm and collegial demeanor during the intense and stressful times around the flybys, as well as his clear and conversational style with the international media spotlight covering Voyager. I was also impressed that he happily tolerated and even sometimes interacted with our small gang of students hanging out in the Imaging Team rooms at JPL so that we could witness the flybys first-hand (there was no internet!)

Later, I had the pleasure of actually getting to know Ed when he provided, over several years, numerous interviews and reviews of material for my book, "The Interstellar Age."  Ed's cheerful and selfless guidance was critical as I struggled to understand and translate the esoteric concepts of Voyager's interplanetary and interstellar fields and particles research into common language.

Ed was a consummate scientist, instrument and mission team leader, and public communicator. He was also a great friend of The Planetary Society. He will be greatly missed as a mentor and colleague in our community.”

—Jim Bell, Secretary and Past President of The Planetary Society’s Board of Directors, Professor at the School of Earth and Space Exploration at Arizona State University, and Principal Investigator for NASA’s Perseverance rover Mastcam-Z instruments

“I worked with Ed when I served on the Voyager Mission team in the late 1980s.  His leadership of the Voyager project truly changed the course of planetary exploration, both through its fundamental and transformative science and through its outreach. Ed embodied many of the principles I internalized and used for science communication and team engagement for my leadership of the Hubble Shoemaker-Levy 9 team in 1994.”

—Heidi Hammel, Vice President of The Planetary Society’s Board of Directors, and Vice President for Science at AURA

“Ed Stone was a remarkable scientist, a great guy, and especially, a remarkable leader. The world will always know his work. The Voyager missions continue to change the way citizens everywhere think of the Cosmos and our place within it. He spoke with me several times over the years at NASA in D.C., or JPL, and at Planetary Society headquarters. He was a gentle, thoughtful, passionate explorer, and a loyal, warm, engaging member of our merry band at The Planetary Society. He will be missed.”

—Bill Nye, CEO of The Planetary Society

“Ed was a brilliant scientist, and inspirational leader, and outstanding leader of the everlasting Voyager mission and a wonderful friend and colleague for more than 50 years.

Everyone one of us involved in the Voyager mission, have so much to thank Ed Stone for.

Throughout the Voyager mission the scientists and engineers would meet with the world’s media in the Von Karman auditorium at JPL. Ed Stone would always meet with the people presenting and listen to their contributions.

During the Voyager 2 Saturn encounter, I was presenting results of some new cloud features and was discussing the detailed meteorological aspects of the observations with my co-investigators, Andy Ingersoll (CalTech) and Vern Suomi (Wisconsin), when Ed joined us. He quickly asked many probing questions that were very testing for us three very experienced atmospheric physicists.

I learnt a great deal from my long friendship and working relationship with Ed Stone. He will be missed greatly.”

—Garry Hunt, OBE, member of The Planetary Society’s Advisory Council