Let's get ready for Juno's highlight of the year - an extremely close flyby of Jupiter's moon Io!
The NASA Juno spacecraft will make its 57th flyby of Jupiter (Perijove 57) on Sat Dec 30 around 7:39 a.m. ET (12:39 UTC).
A few hours earlier, around 3:36 a.m. ET (08:36 UTC), it will swing by the Galilean moon Io at a distance of 1,500 km. The record will still be held by the Galileo spacecraft which came within 200 km in 2000.
Here is a list of flybys of Io by the Juno spacecraft over the past 18 months.
Current 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 = 35 days, allowing it to visit Io on PJ58.
Juno orbital period after PJ58 = 33 days.
After PJ58, flyby distance to Io will increase. Also, Juno will enter Jupiter's shadow for ~5 minutes on each PJ.
NASA states that during the flyby of Io, all 3 cameras aboard Juno will be active.
The Jovian Infrared Auroral Mapper (JIRAM) will collect heat signatures of Io's volcanoes and calderas.
The Stellar Reference Unit (a highly sensitive, visible wavelength (450-1100 nm) navigational star camera also used for science data) will obtain the highest-resolution image of the surface to date.
The venerable JunoCam imager will take visible-light color images.
Launched in 2011, Juno reached Jupiter in July 2016 and was expected to perform 36 14-day science orbits until end of mission in 2018. Instead, it performed ~32 38-day orbits until its prime mission ended in 2021.
The mission was extended until 2025, with 42 additional orbits, including close passes of Jupiter’s north pole, its moons and rings.
The later orbits spend more time inside Jupiter's ferocious radiation belts, risking damage to spacecraft electronics.
Unfortunately, Juno's JunoCam camera seems to have taken a beating from Jupiter's radiation belts.
Ed Hirst, proj mgr of Juno - “The cumulative effects of all that radiation has begun to show on JunoCam over the last few orbits. Pictures from the last flyby show a reduction in the imager’s dynamic range and the appearance of ‘striping’ noise. Our engineering team has been working on solutions to alleviate the radiation damage and to keep the imager going.”
🤞 https://www.nasa.gov/missions/juno/nasas-juno-to-get-close-look-at-jupiters-volcanic-moon-io-on-dec-30/ #Juno
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JunoCam is a wide-angle camera, added late in the program, intended primarily for public outreach purposes. The Galileo spacecraft employed a narrow-angle camera with a high-power telescope. The table below summarizes the key parameters of the 2 cameras.
During this flyby, Juno's resolution will be around 0.95 km/pixel and its FOV will cover ~40% of the width of the moon.
Here is the iconic image of a volcano eruption on Io captured by the Galileo spacecraft on June 28, 1997 from an altitude of ~600,000 km.
The plume on the left is over a caldera named Pillan Patera. The plume was also detected by the Hubble Space Telescope.
There is another plume named Prometheus over a volcano near the center of the image.
Let's hope Juno catches a volcano in its act on Io!
Let's take a look at some past images of Jupiter's volcanic moon Io taken by the Juno spacecraft.
This 1123x1120 infrared image of Io was taken on July 5, 2022, from a distance of 80,000 km. The image was derived from data collected by Juno's Jovian Infrared Auroral Mapper (JIRAM) instrument. In this image, the brightness of the color represents surface temperature.
Tomorrow, Juno will be just 1,500 km away from Io's surface at close approach.
These composite images of Io were generated using JunoCam and JIRAM during Juno's flybys on Dec 14, 2022 (left) and Mar 1, 2023.
The background images of Io were taken by JunoCam in visible light.
The speckled overlays are based on data from Juno's JIRAM (Jovian Infrared Auroral Mapper) instrument. They highlight hot spots around volcanic activity. The JIRAM infrared (5 µm wavelength) data was taken from distances of 80,000 km and 58,000 km resp.
🟤 La sonde #Juno de la NASA va effectuer ce samedi un survol rapproché de la lune #Io de #Jupiter à 1500 km d’altitude. Un autre “flyby” est prévu le 3 février.
📷 NASA/JPL-Caltech/SwRI/MSSS d’un précédent survol
🪷 (Juno art by #AntoniusSubia) ... December 13th is the feast of Juno Lucina, #Juno the Light Bringer, who has been christianised as St. Lucy. Near the Winter Solstice, this is one of the festivals which encourages the light of the Sun to rekindle and return to warm the Earth. 🪷
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.