The spaceship may have found where the colorless gas hid in the solar system’s largest planetary inhabitants.
New results from NASA’s Juno mission to Jupiter suggest that our solar system is the largest planet home to what is known as the “shallow lightning.” An unexpected form of electrical discharge, shallow lightning originates from clouds containing an ammonia-water solution, while lightning on earth originates from water clouds.
Other new findings suggest the violent thunderstorms that the gas giant is known for can form slushy ammonia-rich hail Juno’s science team calls “mushrooms”; they theorize that mushrooms essentially kidnap ammonia and water in the upper atmosphere and carry them deep into Jupiter̵
The shallow lightning falls will be published on Thursday 6 August in the journal Nature, while sponge ball research is currently available online in the Journal of Geophysical Research: Planets.
Since NASA’s Voyager mission first saw Jovian lightning in 1979, it has been thought that the planet’s lightning is similar to Earth’s, and occurs only in thunderstorms where water is present in all its phases – ice, liquid and gas. At Jupiter, this would place the storms between 45 and 65 miles below the visible clouds, with temperatures hovering around 32 degrees Fahrenheit (0 degrees Celsius, the temperature at which water freezes). Voyager, and all other missions to the gas giant before Juno, saw lightning as bright spots on Jupiter’s cloud tops, indicating that the lightning originated in deep water clouds. But lightning strikes observed on Jupiter’s dark side of the Junos Stellar Reference Unit tell a different story.
“Junos near flybys of the cloud tops allowed us to see something surprising – smaller, shallower lightning – emanating from much higher altitudes in Jupiter’s atmosphere than previously thought possible,” said Heidi Becker, Juno’s radiation monitoring study at NASA’s Jet Propulsion Laboratory in Southern California and lead author. of the Nature paper.
Becker and her team suggest that Jupiter’s severe thunderstorms throw water-ice crystals high into the planet’s atmosphere, more than 250 km above Jupiter’s water clouds, where they encounter atmospheric ammonia vapor that melts the ice and forms a new ammonia water solution. At such high altitudes, the temperature is below minus 126 degrees Fahrenheit (minus 88 degrees Celsius) – too cold for pure liquid water to exist.
This animation takes the viewer on a simulated journey into Jupiter’s exotic electric storms at high altitude. Get a close-up view of Mission Juno’s newly discovered “shallow lighting” flashing and diving into the violent atmosphere of the Nautilus cloud. Credit: NASA / JPL-Caltech / SwRI / MSSS / Kevin M. Gill
“At these altitudes, ammonia acts as an antifreeze, lowering the melting point of water ice and allowing the formation of a cloud of ammonia-water liquid,” Becker said. “In this new state, falling droplets of ammonia-water liquid can collide with the ongoing water-ice crystals and electrify the clouds. It was a big surprise, because ammonia-water clouds are not present on earth.”
The Shallow Lightning Factors in Another Puzzle About the Inner Effects of Jupiter’s Atmosphere: Juno’s microwave radiometer discovered that ammonia was drained – that is, missing – from most of Jupiter’s atmosphere. Even more puzzling was that the amount of ammonia changes as you move within Jupiter’s atmosphere.
“Previously, scientists realized that there were small pockets of missing ammonia, but no one realized how deep these pockets went or that they covered most of Jupiter,” said Scott Bolton, Juno’s principal investigator at the Southwest Research Institute in San Antonio. “We struggled to explain the ammonia depletion with only ammonia water rain, but the rain could not go deep enough to match the observations. I realized that a solid, like a hailstone, could go deeper and absorb more ammonia. When Heidi discovered shallow lightning, we realized that we had evidence that ammonia was mixed with water high in the atmosphere, and thus lightning was an important part of the puzzle. “
This graphic shows the evolutionary process of “shallow lightning” and “mushrooms” on Jupiter. Image credit: NASA / JPL-Caltech / SwRI / CNRS
›Full image and caption
A second paper, released yesterday in the Journal of Geophysical Research: Planets, depicts the strange brew of 2/3 water and 1/3 ammonia gas that becomes seed for jovial hailstones, known as mushrooms. Consisting of layers of water-ammonia slave and ice covered by a thicker water-ice crust, sponge balls are generated in the same way that hail is on the earth – by growing larger as they move up and down through the atmosphere.
“Eventually, the mushroom balls become so large, even the updates can not hold them, and they fall deeper into the atmosphere and meet even warmer temperatures, where they eventually evaporate completely,” said Tristan Guillot, a Juno co-researcher at the Université Côte d ‘ Azur in Nice, France, and lead author of the second essay. “Their action pulls ammonia and water down to deep levels in the planet’s atmosphere. That explains why we do not see much of it in these places with Juno’s microwave radiometer.”
“Combining these two results was crucial in solving the mystery of Jupiter’s lack of ammonia,” Bolton said. “It turned out that the ammonia is not actually missing; it is only transported down while it is in disguise, has cut itself by mixing with water. The solution is very simple and elegant with this theory: When the water and ammonia are in a liquid state, they are invisible to us until they reach a depth where they evaporate – and that’s pretty deep. “
Understanding Jupiter’s meteorology enables us to develop theories of atmospheric dynamics for all planets in our solar system as well as for exoplanets discovered outside our solar system. Comparing how violent storms and atmospheric physics work across the solar system enables planetary scientists to test theories under different conditions.
More about the mission
The solar-powered Jupiter explorer was launched nine years ago today, August 5, 2011. And last month marked the fourth anniversary of its arrival in Jupiter. Since entering the gas giant’s orbit, Juno has performed 27 scientific flybys and logged over 300 million miles (483 million kilometers).
JPL, a division of Caltech in Pasadena, California, is handling the Juno mission for Chief Investigator Scott Bolton of the Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers program, managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington. Lockheed Martin Space in Denver built and operates the spaceship.
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