Since entering Jupiter’s orbit in 2016, NASA’s Juno spacecraft has been hard at work unraveling many of the mysteries of the solar system’s largest planet. And its latest discovery may be one of the most intriguing: a completely new type of plasma wave near Jupiter’s poles.
In a paper published in the journal Physical Review Letters, astronomers describe an unusual pattern of plasma waves in Jupiter’s magnetosphere, the magnetic “bubble” that shields the planet from external radiation. Jupiter’s extremely powerful magnetic field appears to require two very different types of plasma to move in tandem, creating a unique flow of charged particles and atoms at its poles.
Plasma is a key force in shaping Jupiter’s turbulent atmosphere. As such, researchers believe the new observations will further our understanding not only of Jupiter’s weather, but also of the magnetic properties of distant exoplanets.
For the study, scientists analyzed the behavior of plasma waves in Jupiter’s magnetosphere, which contains highly magnetized, low-density plasma. The team, which included researchers from the University of Minnesota, the University of Iowa, and the Southwest Research Institute in Texas, found unexpected oscillations between Alfvén waves and Langmuir waves, which reflect the motion of plasma atoms and the motion of electrons in plasma, respectively.
The electrons took advantage of the lighter ones for the charged atoms, meaning that traditionally the two types pulsate at very different frequencies—something that clearly wasn’t the case in Jupiter’s magnetosphere, prompting the researchers to take a closer look. Further investigation revealed a previously unseen type of plasma oscillation near Jupiter’s poles.
“The observed plasma properties are truly unusual, and have not been seen before in other parts of our solar system,” John Leif Jørgensen, a planetary scientist at the Technical University of Denmark who was not involved in the new work, told New Scientist.
Unlike Earth’s auroras, which are caused by solar storms, Jupiter’s auroras—a flurry of energetic, ultrafast particles that are up to ten times more energetic than Earth’s auroras—are sometimes produced as a product of its powerful magnetic field. The study authors say that better understanding how such phenomena work could provide valuable information for future missions to search for alien life on exoplanets.
“Although such conditions are not found [on] Earth, it is possible that they are reflected in the polar regions of other giant planets and, possibly, on highly magnetized exoplanets or stars,” the astronomers write in the paper.
“Jupiter is the Rosetta Stone of our solar system,” said Scott Bolton, Juno’s principal investigator, on NASA’s introductory page about the spacecraft. “Juno is there as our emissary to interpret what Jupiter has to say.”
NASA originally expected Juno’s mission to end in 2017, when the spacecraft would intentionally enter Jupiter’s atmosphere, meeting NASA’s requirements for protecting the planet. But Juno’s flight path changed over time, and NASA concluded that the spacecraft would no longer pose a threat to Jupiter’s moons. As a result, the agency decided to continue the mission.
However, scientists believe that by September of this year, Juno’s orbit will naturally deteriorate and it will be absorbed into Jupiter’s atmosphere. However, this exploration of Jupiter is by no means over: Europa Clipper is due to reach Europa, Jupiter’s moon, in 2030 (last we checked, it had made several flybys of ex-Mars). Of course, even after Jupiter swallows Juno, users will have inputted a wealth of invaluable data from the spacecraft, which they will continue to analyze in the years to come.
