By analyzing Juno spacecraft mission data, researchers at UC Berkeley and California Institute of Technology, or Caltech, were able to uncover previously unsolved principles of fluid motion.
The Juno spacecraft, which has been in pole-to-pole orbit around Jupiter since July 2016, has found polygonal cyclone patterns, a phenomenon caused by several hurricane-like cyclones spinning together to form shapes at the planet’s north and south poles, according to Caltech planetary science professor Andrew Ingersoll, a co-author of the study. The north pole has nine total vortices that form an octagon, and the south pole has six that form a pentagon, both with central vortices.
“This is the first time we have seen Jupiter’s pole and this is the first time something like this has been published,” said Juno team member, UC Berkeley researcher and study co-author Cheng Li.
Li has been interested in studying Jupiter’s polygonal vortices since he first saw Juno’s mission data three years ago.
Upon viewing the data, researchers wondered why the vortices at each pole have not merged together, added Ingersoll.
“It’s a natural laboratory that we can’t have on Earth,” Li said. “Jupiter is essentially a fluid, and we have learned a lot about fluid motions by studying it. It’s the perfect place to study what nature and fluids can do that we cannot imagine.”
By running computer simulations of Jupiter’s atmosphere, researchers found that the stability of these polar cyclones was caused by anticyclonic rings surrounding them in a process called shielding, Ingersoll said.
Anticyclonic rings are caused by fluid spinning in the opposite direction of the interior cyclone, according to Ingersoll.
Too much shielding makes the cyclones and anticyclonic rings fly apart, while too little shielding causes the interior cyclones to merge, destroying the polygonal pattern, according to the study.
“This tells us about how atmospheres work in a more general context than what we would see on Earth,” Ingersoll said.
The researchers, however, still do not understand the mechanism behind shielding in Jupiter’s polygonal cyclones, according to the study.
Juno will continue to orbit Jupiter until July, according to the NASA website. Li added that NASA may extend the mission by five years.
Li said Juno videotapes Jupiter as it orbits around the planet and has measured the planet’s composition, collecting data such as oxygen abundance. He added that Juno is the first machine to fly within Jupiter’s radiation belt so it can collect temperature and radiation coming from deep within the planet.
The radiation belt, according to Li, is made of charged particles trapped by a planet’s magnetic field. He noted that Jupiter actually has the strongest radiation belt in the solar system, and if one looks at Jupiter from a telescope on Earth, they are likely to see bright lobes of radiation obscuring the planet’s atmosphere. Li added that this is why Juno needed to be under Jupiter’s radiation belt to observe it.
“Jupiter is the largest planet in the solar system, it also formed the first,” Li said. “It trapped a lot of materials that were at the formation of the solar system. … By studying Jupiter’s atmosphere, we can study the early solar system. It’s like a fossil.”