Juno makes the first close flyby of the volcano-covered moon Io

NASA's Juno spacecraft, which has been orbiting Jupiter for the better part of a decade, on Saturday made its closest flyby of the innermost moon in the Jovian system.

The spacecraft came within 930 miles (1,500 kilometers) of the surface of Io, a dense moon that is the fourth largest in the solar system. Unlike many of the moons surrounding Jupiter and Saturn, which have surface ice or subsurface water, Io is an extremely dry world. It is also very geologically active. Io contains more than 400 active volcanoes and is therefore of great interest to astronomers and planetary scientists.

The photos were from the flight on December 30th Published by NASA During New Year's weekend, it provides some of the clearest views yet of this hell-filled world. The new data will help planetary scientists determine how often these volcanoes erupt and how this activity relates to Jupiter's magnetosphere, where Io is exposed to intense radiation from the gas giant planet.

Until now, Juno has mostly observed Io from afar, with the spacecraft making 56 flybys of Jupiter, studying the complex gas giant in far greater detail than ever before. Since arriving in the planetary system in July 2016, Juno has previously come within several thousand miles of the Moon. Juno will perform another flyby of Io on February 3, 2024, and this will allow scientists to compare changes on the moon's surface over a short period of time.

Since its launch on an Atlas V rocket, Juno has performed very well while operating in the Jovian system, surviving extended operations under the planet's harsh radiation. This poses a major challenge for any spacecraft heading to Jupiter, which must carry radiation-hardened instruments, including their cameras.

“The cumulative effect of all this radiation has been starting to show up on JunoCam over the last few orbits.” He said Ed Hirst, Juno project manager at NASA's Jet Propulsion Laboratory in Southern California. “Images from the recent flyby show a decrease in the dynamic range of the imager and the appearance of 'striping' noise. Our engineering team is working on solutions to mitigate radiation damage and keep the imager operational.”

Ultimately, radiation will win out, so NASA plans to get rid of Juno before it ceases operations. Originally, the space agency planned to end the rover's life in 2018, but since Juno was a survivor as it explored the largest planet in the solar system, the spacecraft is now scheduled to operate until September 2025.

However, at that point, it will descend into Jupiter's atmosphere to burn up, so as not to contaminate any of the planet's moons with any stray microbes on Earth, although that is unlikely.