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Keeping Up with Juno

We’re getting interesting results from analysis of Juno’s close flybys of Jupiter. The spacecraft has detected hydrogen, oxygen and sulfur ions moving at relativistic speeds in a new radiation zone just outside the atmosphere. We have its JEDI (Jupiter Energetic Particle Detector Instrument) to thank for the detection, which was made during approaches as close as 3400 kilometers from the cloud tops. Fast moving atoms without an electric charge — energetic neutral atoms — are thought to be the source of the new radiation zone as they move from gas around Io and Europa and become ionized in Jupiter’s upper atmosphere.

The new radiation zone is inside Jupiter’s previously known radiation belts, which have also been under scrutiny by Juno. High-energy, heavy ions have been detected in the inner edges of the planet’s electron radiation belt, previously thought to be made up primarily of electrons moving at near light speed. The heavy ions show up at high latitude locations within the electron belt, detected by Juno’s Stellar Reference Unit (SRU-1) star camera. You can see the locations where they were detected in the bright spots along the white line of Juno’s flight path below.

“The closer you get to Jupiter, the weirder it gets,” said Heidi Becker, Juno’s radiation monitoring investigation lead at JPL. “We knew the radiation would probably surprise us, but we didn’t think we’d find a new radiation zone that close to the planet. We only found it because Juno’s unique orbit around Jupiter allows it to get really close to the cloud tops during science collection flybys, and we literally flew through it.”

Image: This graphic shows a new radiation zone surrounding Jupiter, located just above the atmosphere near the equator, that has been discovered by NASA’s Juno mission. The new radiation zone is depicted here as a glowing blue area around the planet’s middle. Credit: NASA/JPL-Caltech/SwRI/JHUAPL.

Meanwhile, Juno’s microwave radiometer (MWR) instrument also culled data during Juno’s passage over the Great Red Spot in July of 2017. The figure below represents six channels of these data. Using the MWR, Juno can see deeper than any previous ground- or space-based observations into the clouds. It’s interesting to note that the large-scale structure of the Great Red Spot is evident as deep into the planet as the MWR can observe. 16,000 kilometers wide, the Great Red Spot is a vast crimson storm that has been monitored since 1830. It was twice Earth’s diameter when the Voyagers studied it but has since diminished in width.

Image: This figure shows data from the six channels of the microwave radiometer (MWR) instrument onboard NASA’s Juno spacecraft. The data were collected in the mission’s sixth science orbit (referred to as “perijove 7”), during which the spacecraft passed over Jupiter’s Great Red Spot. The top layer in the figure is a visible light image from the mission’s JunoCam instrument, provided for context. Credit: NASA/JPL-Caltech/SwRI.

“Juno found that the Great Red Spot’s roots go 50 to 100 times deeper than Earth’s oceans and are warmer at the base than they are at the top,” said Andy Ingersoll, professor of planetary science at Caltech and a Juno co-investigator. “Winds are associated with differences in temperature, and the warmth of the spot’s base explains the ferocious winds we see at the top of the atmosphere.”

But below is the image that awakens the science fiction fan in me. It’s an animation assembled from JunoCam imagery to give us a sense of the winds in the Great Red Spot, using a velocity field model derived from earlier observations including those from Voyager. The animation is the work of two citizen scientists, Gerald Eichstädt and Justin Cowart, with Juno scientists Shawn Ewald and Andrew Ingersoll applying the velocity data to produce the finished animation.

Image: Winds around Jupiter’s Great Red Spot are simulated in this JunoCam view that has been animated using a model of the winds there. The wind model, called a velocity field, was derived from data collected by NASA’s Voyager spacecraft and Earth-based telescopes. NASA’s Juno spacecraft acquired the original, static view during passage over the spot on July 10, 2017. Credit: NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstadt/Justin Cowart.

If you’d like to dig into the analysis of radiation data, the paper is Kollman et al., “A heavy ion and proton radiation belt inside of Jupiter’s rings,” Geophys. Res. Lett 44, 5259-5268 (abstract).


Comments on this entry are closed.

  • Alex Tolley December 13, 2017, 16:49

    I’m currently reading The Medusa Chronicles based on Clarke’s A Meeting with Medusa. I look forward to comparing the reality of Juno’s findings with the depictions of Jupiter’s depths by Reynolds and Baxter.

  • ljk December 20, 2017, 12:13

    Art meets astronomy: the JunoCam experiment

    A camera on NASA’s Juno craft is a attracting a lot of attention from amateur astronomers and artists. Richard A Lovett reports.


    To quote:

    The project uses an instrument called JunoCam, which was put on the spacecraft largely to reach out to the public and share the excitement of space exploration, according to Candice Hansen, of the Planetary Science Institute in Tucson, Arizona, US, and one of JunoCam’s principal investigators.

    But that doesn’t mean the instrument was an afterthought, even though the Juno mission’s primary objectives, which involve measuring Jupiter’s radiation belts and using microwave and gravity sensors to map its internal structure, didn’t require a camera. There were parts of Jupiter near its poles that had never before been imaged, because they aren’t at the right angle to be seen by the Hubble Space Telescope. “The team and myself couldn’t imaging going over the poles and not seeing what they looked like,” says Scott Bolton, the mission’s principal investigator. “We all wanted that poster in our room.”

    Technically, the camera has a resolution of about 15 kilometres per pixel at the distances involved in Juno’s once-every-53-days close flybys. That’s not great by the standards of spacecraft currently orbiting the Moon and Mars, but JunoCam also has a 58-degree field of view. That makes it just right for what the scientists wanted.

    “If you were close to Jupiter, your eyes would take in a great view,” Bolton says.

    But if you tried to look through binoculars, “you would look at only one spot. You lose your ability to see the context.”

  • ljk January 10, 2018, 10:40

    The Japanese space probe Akatsuki is doing for Venus what Juno is doing for Jupiter in terms of beautiful images of the planet – and oh yeah, science:


  • ljk January 16, 2018, 12:22

    JUICE ground control gets green light to start development of Jupiter operations


  • ljk January 24, 2018, 11:29

    Juno spacecraft captures stunning images of Jupiter’s cloud tops, storms

    SpaceFlight Insider

    Because the picture was taken so close to the surface, the planet’s curve cannot be seen in it. An image captured from a greater distance, 64,899 miles (104,446 km) from the cloud tops, shows Jupiter’s south polar region. The color-enhanced image, in which the south pole appears blue, has a …


  • ljk February 16, 2018, 12:33

    Fresh raw imagery from NASA’s Juno orbiter puts Jupiter’s fans in 11th heaven

    To quote:


    For still more views, check out the mission’s JunoCam gallery:


    The close encounters for picture-taking come roughly every 54 days — which means the next opportunity, Perijove 12, is set for April 1.

    The cycle will continue until 2021, and then the radiation-battered probe will fire its thrusters for a fatal plunge into Jupiter’s cloud tops. That maneuver is part of NASA’s plan to make sure Juno leaves no debris that could smash into Europa or other potential abodes for life in the Jovian system.