Jupiter lightning more Earth-like than previously thought

Saturday, 09 Jun, 2018

Analysis of the radio spectrum indicated that one source of these transmissions were lightning bolts arcing through the Jovian atmosphere, a billion times more powerful than those on Earth.

"They were recorded in the megahertz as well as gigahertz range, which is what you can find with terrestrial lightning emissions", said Brown. Specifically, the mission's main objective is to try and determine how much water is in the planet's atmosphere and to measure its composition, temperature, cloud patterns, and map its magnetic and gravity fields.

"But until Juno, all the lightning signals recorded by spacecraft were limited to either visual detections or from the kilohertz range of the radio spectrum, despite a search for signals in the megahertz range".

"No matter what planet you're on, lightning bolts act like radio transmitters, sending out radio waves when they flash across a sky", said Shannon Brown, a Juno researcher at NASA's Jet Propulsion Laboratory in Pasadena, California.

Since then, NASA's Galileo and Cassini, which whizzed near Jupiter on its way to Saturn, validated the initial theories that lightning on Jupiter occurs.

This discovery was backed up in the second article, published by a team of scientists of the Academy of Sciences of the Czech Republic, which presented the most famous record collection of lightning with a giant planet.

NASA's Juno mission has been saved from its death plunge into the surface of Jupiter - for now - as the space agency extended the probe's expedition through at least 2021 so it can continue to orbit and map the solar system's largest planet.

"Many theories were offered up to explain it, but no one theory could ever get traction as the answer", Brown said of the problem.

An artist's impression of lightning bolts in the atmosphere if Jupiter. In a pair of studies, scientists are saying that lightning in the giant planet may be much more familiar to Earthlings than originally believed.

The previous observations of Jupiter's lightning found very low-frequency, lightning-generated radio waves compared to the radio waves of Earth's lightning. The spacecraft came nearly 50 times closer to the planet than Voyager 1 ever did, flying "closer to Jupiter than any other spacecraft in history", states Juno's principal investigator Scott Bolton from the Southwest Research Institute in San Antonio, who was involved in both studies. At that distance, Jupiter receives 25 times less sunlight than Earth.

When Juno flew by the planet in 2016, she used a wide range of highly sensitive instruments to record the emissions of a gas giant.

In the data from Juno's first eight passes by the planet, the spacecraft's Microwave Radiometer Instrument (MWR) detected 377 Jovian lightning discharges.

"That distribution of lightning is kind of upside-down from what we'd expect on Earth", he said. Its mission managers initially wanted to destroy the orbiter by plunging it into Jupiter's clouds sometime after it concludes its mission in July. As Jupiter produces lightning through electrical reactions between ice and water droplets, the lightning's location suggests that the water-filled gas in the atmosphere circulates toward the poles.

A new paper published by NASA's Juno mission comes to flesh out our understanding of Jovian lightning.

The decision to fund the Juno mission through fiscal year 2022 was made after an "independent panel of experts" ruled that it was on track to "achieve its science objectives and is already returning spectacular results".