In December 2023 and February 2024, NASA’s Juno spacecraft, presently in orbit round and investigating Jupiter and the Jovian system, made a number of shut flybys of the innermost of the Galilean moons, Io. Throughout the flybys, Juno got here as shut as 1,500 kilometers from the floor of Io, throughout which intensive information and imagery of the moon had been captured.
From the imagery and information, scientists had been capable of make the primary up-close observations of the northern latitudes of Io, in addition to sharp mountains and lava lakes. Moreover, Juno’s current flybys of Jupiter allowed scientists to refine their understanding of Jupiter’s polar cyclones and water abundance.
Io’s lava lakes and sharp mountains
Io is understood to be one of the excessive areas within the photo voltaic system, with the moon having probably the most geologic/volcanic exercise of any planetary physique within the photo voltaic system. Io’s immense volcanic exercise has been recorded by a number of spacecraft, with photos exhibiting giant plumes of sulfur and sulfur dioxide capturing as excessive as 500 kilometers above the floor.
Io’s volcanism is basically as a consequence of a two-to-one mean-motion orbital resonance with Europa, and a four-to-one mean-motion orbital resonance with Ganymede — which means that Io completes two orbits of Jupiter with each orbit of Europa, and 4 orbits with each one orbit of Ganymede. These resonances increase and contract the floor of Io, which then permits Jupiter’s gravity to warmth the inside of the moons, offering the heating wanted for Io’s excessive geologic exercise.
“Io is just plagued by volcanoes, and we caught a couple of of them in motion. We additionally received some nice close-ups and different information on a 200-kilometer-long (127-mile-long) lava lake referred to as Loki Patera. There may be wonderful element exhibiting these loopy islands embedded in the midst of a probably magma lake rimmed with sizzling lava. The specular reflection our devices recorded of the lake suggests components of Io’s floor are as clean as glass, paying homage to volcanically created obsidian glass on Earth,” mentioned Scott Bolton, Juno’s principal investigator.
Utilizing the Juno information, the crew was capable of create two simulations that visualize the traits of the lava lake, Loki Patera, and sharp mountains, one in every of which is Steeple Mountain.
Further information from the flyby utilizing Juno’s Microwave Radiometer instrument (MWR) exhibits that Io’s floor is comparatively clean in comparison with the surfaces of the opposite three Galilean moons, that are Ganymede, Callisto, and Europa. Moreover, MWR additionally discovered that Io’s poles are colder than the moon’s center latitudes.
Jupiter’s pole place
Juno efficiently inserted itself into orbit round Jupiter in July 2016. The unique mission plans had the spacecraft deorbit into Jupiter’s ambiance after finishing 32 orbits of Jupiter, the place it will in the end expend and disintegrate. Nonetheless, with the spacecraft remaining in good situation and all of its devices nonetheless working as anticipated, NASA awarded Juno and its crew a mission extension in 2021 that may have the spacecraft full 42 extra orbits of Jupiter. Juno is predicted to finish its mission extension in September 2025.
Juno’s trajectory for its mission extension brings the spacecraft nearer and nearer to Jupiter’s north pole with every orbit. This trajectory permits for the MWR instrument to repeatedly enhance its decision of the planet’s north pole, which is full of huge polar cyclones. The brand new information permits scientists to match the poles and the cyclones in a number of wavelengths, and scientists have discovered that not all polar cyclones are created equally.
“Maybe probably the most placing instance of this disparity will be discovered with the central cyclone at Jupiter’s north pole. It’s clearly seen in each infrared and visual mild photos, however its microwave signature is nowhere close to as sturdy as different close by storms. This tells us that its subsurface construction should be very completely different from these different cyclones. The MWR crew continues to gather extra and higher microwave information with each orbit, so we anticipate growing a extra detailed 3D map of those intriguing polar storms,” mentioned Juno challenge scientist Steve Levin of NASA’s Jet Propulsion Laboratory in California.
Jupiter’s northern polar cyclones, seen in infrared by Juno. (Credit score: NASA/JPL-Caltech/SwRI/MSSS)
Water abundance inside Jupiter
Understanding water abundance inside Jupiter is among the main science targets for Juno’s mission. Nonetheless, the crew isn’t looking for liquid water, however relatively investigating the presence of oxygen and hydrogen molecules — the molecules that make up water — inside Jupiter’s huge ambiance. Getting an estimate of Jupiter’s water abundance is essential for understanding the formation of the photo voltaic system and Jupiter.
Scientists imagine that Jupiter was the primary planet to type, which implies it doubtless comprises a lot of the gasoline, mud, and different cosmic materials left over from the formation of the Solar and our photo voltaic system. Having perception into the abundance of various molecules and supplies throughout the planet offers scientists the possibility to document what supplies had been current throughout the formation of our photo voltaic system.
Water abundance, particularly, is essential for Jupiter’s meteorology, together with the movement of wind currents, and the planet’s inside construction. Scientists have been attempting to measure Jupiter’s water abundance for many years, with NASA’s Galileo mission amassing one of many first datasets on Jovian water abundance in 1995 throughout the spacecraft’s 57-minute entry into Jupiter’s ambiance on the finish of its mission. Nonetheless, Galileo’s information created extra confusion than readability, because the spacecraft discovered that the planet’s ambiance was sizzling and void of water.
“The probe did wonderful science, however its information was to this point afield from our fashions of Jupiter’s water abundance that we thought-about whether or not the placement it sampled may very well be an outlier. However earlier than Juno, we couldn’t verify. Now, with current outcomes made with MWR information, now we have nailed down that the water abundance close to Jupiter’s equator is roughly three to 4 occasions the photo voltaic abundance when in comparison with hydrogen. This definitively demonstrates that the Galileo probe’s entry web site was an anomalously dry, desert-like area,” Bolton mentioned.
The northern and equatorial areas of Jupiter, imaged by Juno throughout its tenth flyby of the planet. (Credit score: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill)
Juno’s new outcomes on Jovian water abundance counsel very low water abundance—an surprising consequence that scientists are nonetheless attempting to know. Nonetheless, these outcomes do help scientists’ theories that throughout the photo voltaic system’s formation, water-ice materials was doubtless a driving power behind heavy factor enrichment, the method by which chemical components heavier than hydrogen and helium had been accreted by Jupiter throughout its formation.
Further information on Jovian water abundance collected by Juno throughout the the rest of its prolonged mission will assist scientists evaluate Jupiter’s water abundance at polar areas and equatorial areas. Further information may even assist reveal the construction of the planet’s core.
Juno’s subsequent flyby of Jupiter, the 61st of the mission, is deliberate for Could 12.
(Lead picture: Picture of Io taken by Juno on October 15, 2023. Credit score: NASA/JPL-Caltech/SwRI/MSSS/Ted Stryk)
