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LOS ANGELES – This data was like nothing, Margaret Kivelson and her team of physicists were never expected.
It was in December 1996 and the Galileo spacecraft had just flown to Europe, an icy moon of Jupiter. The readings returned to the Earth suggested a magnetic field emanating from the moon. Europa should not have a magnetic field, yet it was there – and not even headed in the right direction.
"It's unexpected," she recalls, as strange data arrived. "And it's wonderful."
This would be the most significant of a series of surprises from the Jovian moons. For Kivelson's team, the mission should not have been so exciting.
She and her colleagues had designed the magnetometer that returned the abnormal data. The work of the instrument consisted in measuring the massive magnetic field of Jupiter and all the variations caused by its moons. These results were likely to interest space physicists, but few others.
In other words, Kivelson's instrument was never supposed to change the course of space exploration.
And then it happened. Kivelson and his team will soon prove that they have discovered the first underwater ocean of saltwater on another world.
Kivelson, who turns 90 this month, is Emeritus Professor of Space Physics at the University of California at Los Angeles. For 40 years, she has been actively involved in almost every major NASA trip beyond the asteroid belt. She has a sense of ironic humor and her modesty conceals the breadth of her scientific achievements.
His team has transformed the way magnetometers are used in space missions, becoming an essential discovery tool. As a result, the external solar system is now a hot zone in the search for habitability.
Lately, Kivelson has been a researcher on the plasma instrument of Europa Clipper, NASA's next big trip to the outdoor solar system. The satellite, whose launch is scheduled for 2022, will study the habitability of Europa, the oceanic moon of Jupiter. Kivelson's work will help determine if life could exist, including determining the depth and salinity of the ocean.
The story began with Galileo's unusual encounters with Jupiter's moons in the mid-90s. In the end, Europa had his own way of doing things.
Harvard and hydrogen
Kivelson was born in New York. His father was a doctor. His mother was a teacher. Margy, as her friends call her, excelled very early in mathematics.
"I liked that," she said. "I thought it was one of the easiest topics and I knew that the opinion was not common."
She was accepted to Harvard, who sent women to Radcliffe College – a separate school without faculty. Harvard professors crossed the Commons to repeat their lectures to women. "Women have not been invited to Harvard classrooms," she said.
It was there that she discovered physics, which allowed her to use mathematics so that the answers would have a physical meaning.
In 1955 she joined RAND Corp., a company established to provide research to the Department of Defense, including nuclear weapons research. She was commissioned to work on an equation describing the state of hydrogen at a pressure equivalent to 1 million terrestrial atmospheres.
"There are two places where you experience this kind of hydrogen-related pressure," she said. "One is in a hydrogen bomb and the other in the center of Jupiter."
His experience in theoretical physics and his eventual expertise in celestial sciences brought him to UCLA in 1967. His research on the RAND led him to become the local expert on Jupiter. She quickly became famous in space physics for her theoretical work on some ideas on the ground.
Discovery in the field
When NASA announced what would become the Galileo mission to Jupiter, Kivelson was well positioned to propose a magnetometer.
"I was very immersed in the science already available concerning Jupiter's magnetic field and the particle environment," she said.
Galileo came into orbit around Jupiter in 1995. The first major discovery of Kivelson and his team was an internal magnetic field located on Ganymede, Jupiter's largest moon.
Carol Paty, associate professor of earth sciences at the University of Oregon, said no one expected that such a small and cold object would have chemistry, the thermodynamics and structure needed to create one's own magnetic field.
"Her discovery transformed the scientific understanding of the inner workings of planetary bodies," she said.
Then came the series of meetings between Europa and Galileo.
Geologists had suspected that the icy moon once had an ocean below the surface, but could not tell if it still existed or had frozen for a long time. It would always be a mystery if it were not the anomalous data received by the Galileo magnetometer.
Something strange was going on, and Kivelson and his puzzled team found several ways to explain it. One of these ideas was that Europa's magnetic field was induced by Jupiter.
The idea was that while Europa was moving in the magnetic field of Jupiter, a current was moving through some underground conductor on the moon, creating a miniature magnetic field. This is what triggered the Galileo metal detector.
Because Europa is sometimes above and sometimes below Jupiter, the magnetometer team needed measurements on both sides.
If the magnetic field of the moon changed direction on the other side, it would mean that the field was induced by Jupiter – and thus had an internal conductor. The only thing that would suit the bill would be an underwater seawater.
An overview of Galileo in January 2000 revealed exactly what the Kivelson team had predicted: the definitive proof of a global ocean on Europa.
"This is one of the most fundamental discoveries of global science," said Louise Prockter, director of the Lunar and Planetary Institute in Houston. "It's really a revolution."
Robert Pappalardo, the project scientist for the Europa Clipper mission waiting for NASA, said the discovery had consequences for the entire solar system.
"It really rocked the pendulum toward the plausibility of the oceans in icy worlds …" he said. "The term" oceanic world "did not even exist at the time. 39; era. It's now a class of objects, thanks to Margy's fundamental work. "
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