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Spacecraft Juno orbiting Jupiter.

August 16, 2021

Juno Mission Produces Significant Insight on Early Solar System, Continues Mission Through 2025

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Juno, a spacecraft that has contributed to unshrouding the mystery surrounding the gas giant Jupiter since 2016, will have its mission extended until 2025. 

Prof. Jonathan Lunine, astronomy, has been involved with the mission since it was proposed to NASA, and works with data from several of its instruments.

“NASA typically extends missions that are producing valuable scientific data and for which the spacecraft is in good shape,” Lunine said. “In the case of Juno, we had a spacecraft that was working really well, producing excellent science, and we had a number of science goals that could be accomplished by extending the mission.” 

The original mission was meant to understand the origin and evolution of Jupiter, locate a solid planetary core, and measure the levels of water and ammonia in its atmosphere among other goals

Over the past five years, Juno made 28 trips around the gas giant, each about 53 days long. Lunine has focused on answering how Jupiter formed and how it evolved over time. 

To do so, Lunine made use of a microwave radiometer — which measures the natural radio radiation coming from Jupiter.

“We’re measuring that radiation coming from Jupiter very close up so that other sources of energy don’t interfere with those measurements,” Lunine said. “That’s a very sensitive way of determining, in particular, how much water is inside of Jupiter.”

These measurements will allow NASA to determine the composition of the ice present in the early history of the solar system. According to Lunine, this data could lead to significant clues regarding the origin of water on Earth.

“By measuring the abundance of different elements in Jupiter, we’ll get a sense of what the composition of those icy grains might have been early in the history of the solar system, and that tells us what might have seeded the earth with water and carbon marine molecules,” Lunine said.

Another instrument Lunine works on allows for measuring gravity to determine the core composition on Jupiter, which has led to shocking results. 

Jupiter has what Lunine calls a diffuse core — a sharp difference from the ball of rock and ice it was predicted to possess

“[Juno’s core demonstrates] a very gradual change from hydrogen and helium to a more and more heavy element concentration toward the center,” Lunine said. “That really was not expected at all.” 

First on the list of objectives in extending the mission is further understanding Jupiter’s core. 

In addition, the mission extension can tell scientists more about Jupiter’s magnetic field, which is the strongest of all the planets in the solar system, and how it contributes to the planet’s bizarre qualities.

“We’ll be able to do some flybys of the moons and measure how the moons affect the magnetospheric environment,” Lunine said. 

Moreover, there is even more to be learned about Jupiter’s storms, according to Lunine. Though the most famous one, the Great Red Spot, can easily be seen from Earth, Jupiter has many dozens of other storms occurring simultaneously. These storms are incredibly strong and extremely large, with the biggest of them having a radius larger than Earth. 

“It’s become clear that a lot of the energy that is carried out of Jupiter is carried out in these very violent thunderstorms,” Lunine said. 

These storms occur all over the planet and appear to have some degree of organization towards the poles. “You’ll get like eight storms that are positioned quite symmetrically around the pole,” Lunine said. The explanation is yet unclear.