The NASA Juno spacecraft will make its 56th flyby of Jupiter (Perijove 56) tomorrow around 12:20 UTC, Nov 22, 2023.
A few hours earlier, around 08:10 UTC, it will cross the orbit of Jupiter’s volcanic moon Io. Juno will pass through what is known as the "Io Plasma Torus", the donut shaped region around Io's orbit composed of hot ionized gas (plasma) fed by material from Io's eruptions and shaped by Jupiter's magnetosphere.
The "Io Plasma Torus" is a donut shaped region around Jupiter composed of hot ionized gas (plasma). It is caused by Jupiter's strong magnetic field which rotates faster than Io (10 v 42.5 hours) and the dispersal of about 1,000 kg/second of material (mainly SO2, but also NaCl, S, O, C, K) by Io into the planetary magnetosphere. The torus cross-section is ~210,000 km wide. It glows in UV wavelengths.
Juno's Perijove 56 will occur around 12:20 UTC, Nov 22, 2023 at a distance of 4,400 km above Jupiter's surface.
This is what the close flyby will look like with Io in the distance.
Juno will be quite far from Io after it swings around Jupiter; the closest it will get is 358,300 km. But during the the next 2 flybys, Juno will come within 1,500 km of Io! See next post for details.
Here are a subset of the dates of Jupiter flybys of Juno.
Perijoves 57 and 58 will feature close flybys of the moon Io; Juno will be just 1,500 km from Io's surface during PJ57 and PJ58 on Dec 30 and Feb 3 resp.
Juno orbital period = 38 earth days.
Io orbital period = 42.5 hours (1.77 days).
Juno gets close to Io on every alternate orbit.
Juno orbital period after PJ57 will be 33 days, allowing it to visit Io on PJ58.
Source: https://www.lpi.usra.edu/opag/meetings/jun2022/slides/Bolton.pdf #Juno#Jupiter#Io
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Juno's primary mission ended in July 2021. The mission was then extended until 2025, with 42 additional orbits, including close passes of Jupiter’s north polar cyclones; flybys of Ganymede, Europa, and Io; as well as the first extensive exploration of the faint rings encircling the planet.
The later orbits spend more time inside Jupiter's ferocious radiation belts, risking damage to spacecraft electronics.
Jupiter's rotating magnetosphere cuts across the slower moving Io, causing it to develop 400 kvolts across Io and a 3 million amp current. Some of the ions are pulled into Jupiter's atmosphere along the magnetic lines of force, creating a flux tube and auroras/lightning in the planet's upper atmosphere.
Similarly, ionized atoms in the plasma torus travel along magnetic lines and cause auroras in Jupiter's polar regions.
Similar to Io, Jupiter's other moons Ganymede and Europa also create auroras in Jupiter's polar regions through their interaction with Jupiter's magnetic field. The intense flux of electrons and ions along the magnetic lines directly crossing the moons create auroral spots or "footprints" of each moon seen in the UV image taken by Hubble in 1998. They move across Jupiter's surface in circles, leaving a trail of glowing auroras behind them.
As usual, raw and processed images of Jupiter, taken during Perijove 56, will be posted at the NASA Juno website https://www.missionjuno.swri.edu/junocam/processing
They start getting posted typically within 24 hours.
Juno Perijove 56 is now complete. The Juno spacecraft is now racing away from Jupiter back along its 38-day elliptical orbit. It is currently 125,000 km away from Jupiter. It was 4,400 km from Jupiter's surface near its northern polar region just and hour and 20 minutes ago.
Now we wait for the images captured by JunoCam while scientists wait for data captured by Juno's other instruments like JIRAM, JADE and JEDI.
While we wait, we can enjoy this small sample of Juno's greatest hits. These dazzling images were taken by Juno during its first 50 orbits around Jupiter.
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