Ed Stone, the scientist who guided NASA’s groundbreaking Voyager mission to the outer planets for 50 years and led the Jet Propulsion Laboratory when it landed the first rover on Mars, died Tuesday. He was 88 years old.
A physicist on the ground floor of space exploration, Stone played a leading role in NASA missions to Mars, Jupiter, Saturn, Uranus and Neptune. Discoveries made under his supervision revolutionized scientists’ understanding of the solar system and fueled humanity’s passion for exploring distant worlds.
Carolyn Porco, who worked on imaging on JPL’s Voyager and Cassini missions, called Stone “a totally lovely guy” and “as close to perfect as a project scientist can be.”
“When two science teams got into a tug of war over a spacecraft resource and Ed had to decide between the two, even the guy who lost went thinking: ‘If this is what Ed decided, then this must be the right answer,'” Porco said via email Tuesday told. “I feel very fortunate to have known Ed. And like many people today, I was deeply saddened to learn that he was gone.”
Stone was a 36-year-old Caltech physics professor in 1972 when he was asked to serve as chief scientist for a bold plan to send a pair of spacecraft to explore the solar system’s four giant planets for the first time.
This was the opportunity of a lifetime, but he wasn’t sure he wanted the job.
“I hesitated because I was a pretty young professor at the time. “There was still a lot of research I wanted to do,” he recalled 40 years later.
Still, he agreed, and from the mission’s first encounter with Jupiter in 1979 until its final flyby to Neptune in 1989, Stone became the scientific face of the Voyager mission. He guided the science agenda and helped the public make sense of revolutionary images and data from not only Jupiter, Saturn, Uranus, and Neptune, but also many of their fascinating moons.
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Stone and his more than 200 scientists were the first to discover lightning on Jupiter and volcanoes on its moon Io. They detected six never-before-seen moons around Saturn and found the largest ocean in the solar system on Jupiter’s moon Europa, as well as evidence of geysers on Neptune’s moon Triton.
“Everywhere we looked, we seemed surprised to encounter these planets and their moons,” Stone told the Los Angeles Times in 2011. related to. “Even if I close my eyes, I can remember every bit of it.”
The Voyager 1 spacecraft became the first human-made object to reach interstellar space in 2012, and Voyager 2 did the same in 2018.
The twin probes continue to send weekly communications to Earth from interstellar space. Stone retires in 2022 on the 50th anniversary of the mission.
“Some of Ed lives on on both Voyager spacecraft. The fingerprints of his dedication and sharp leadership are woven into the Voyager mission,” said Linda Spilker, who joined the mission in 1977 and succeeded him as project scientist.
The Voyager mission was Stone’s greatest achievement, but not his only one.
He served as principal investigator on nine NASA missions and co-investigator on five others, including several satellites designed to study cosmic rays, the solar wind, and the Earth’s magnetic field.
In 1991, he became director of the Jet Propulsion Laboratory at La Cañada Flintridge, a position he held for ten years.
It was a time of cost-cutting at NASA, but Stone still managed to launch Galileo’s five-year mission to Jupiter and send the Cassini spacecraft to Saturn. He also headed the agency when it delivered the Mars Pathfinder Sojourner rover to the Red Planet. This was the first time humans placed a robot on the surface of another planet.
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During his tenure at JPL, Stone continued to work and teach at Caltech, even teaching physics to first-year students during some of Voyager’s long interplanetary travel times.
He also served as chairman of the board of directors of the California Assn. For Research in Astronomy responsible for the construction and operation of the W. M. Keck Observatory and its two 10-meter telescopes on Mauna Kea, Hawaii.
Edward Carroll Stone Jr. was born in Iowa on January 23, 1936, and grew up in Burlington, where his father ran a small construction business and his mother kept the company’s books.
The eldest of two brothers, Stone was interested in science from a young age. Under his father’s watchful eye, he learned how to take apart and reassemble all kinds of technology, from radios to cars.
“I’ve always been interested in learning why something is this way and why it’s not that way,” Stone said. he told an interviewer “I wanted to understand, measure and observe” in 2018.
After studying physics at Burlington Junior College, he received his master’s and doctorate from the University of Chicago. Shortly after starting graduate school, news came that in 1957 the former Soviet Union had launched Sputnik, the world’s first artificial satellite.
“Just because of our need to match the Cold War and Sputnik, a whole new field opened up,” he said.
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In 1961, Stone built a device to measure the density of solar-powered particles in the atmosphere traveling into space on an Air Force satellite. Unfortunately, the spacecraft’s transmitter did not work, so only a very limited amount of data was sent back to Earth. . However, it was still sufficient to note that the density of the particles was lower than expected.
Despite the transmitter malfunction, Stone said the project was exciting. “We were taking the first steps in a completely new field of research and discovery,” he said. “We were right in the beginning.”
He joined the faculty at Caltech in 1964 and created more space experiments, this time for NASA.
Stone’s particular interest was cosmic rays; high-velocity atomic nuclei that can result from explosive events on the sun or violent events beyond the solar system.
One of the cosmic ray experiments was among the 11 major Voyager experiments.
Colleagues praised Stone for his leadership of the Voyager science team.
“He was a great hero, a giant among men,” Porco said, adding that Stone was known to treat everyone, from top scientists to graduate students, with respect.
Voyager crew scientist Thomas Donahue put it this way: “Over the years, Ed Stone has proven remarkably adept at keeping a group of prima donnas on track.”
Stone was elected to the National Academy of Sciences in 1984 and received the National Medal of Science from President George H.W. Bush in 1991 for his leadership of the Voyager mission. In 2019, he won the Shaw Prize for Astronomy, an honor that comes with a $1.2 million prize. In 2012, his hometown of Burlington, Iowa, named his new city. middle school after that.
“This is truly an honor because this comes from the community where my journey of discovery began,” Stone said. said a local newspaper.
Decades after Voyager was launched, he was asked to choose his favorite moment from the mission. He singled out the discovery of volcanoes on Jupiter’s moon Io.
“Finding a moon that is 100 times more volcanically active than the entire Earth is really quite striking,” he said. “And this was typical of what Voyager would do for the remainder of its journey through the outer solar system.
“We found that at times nature was much more creative than our models,” he said.
His wife, Alice, whom he met on a blind date at the University of Chicago and married in 1962, dead in December. The couple are survived by two daughters, Susan and Janet Stone, and two grandchildren.
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This story was first published in the Los Angeles Times.