Juno detects the aurora of the moon Callisto in Jupiter’s atmosphere
Though previous observations had detected auroras on Jupiter produced by three of its four Galilean moons — Io, Europa, and Ganymede — scientists had until now been unable to detect a similar aurora produced by the fourth, Callisto.
The Jupiter orbiter Juno finally accomplished this observation for the first time.
[T]o image Callisto’s footprint, the main auroral oval needs to move aside while the polar region is being imaged. And to bring to bear Juno’s arsenal of instruments studying fields and particles, the spacecraft’s trajectory must carry it across the magnetic field line linking Callisto and Jupiter.
These two events serendipitously occurred during Juno’s 22nd orbit of the giant planet, in September 2019, revealing Callisto’s auroral footprint and providing a sample of the particle population, electromagnetic waves, and magnetic fields associated with the interaction.
The research paper describing this detection has just been published.
These secondary auroras are caused by Jupiter’s powerful magnetic field.
The Juno mission itself is about to end. NASA did not approve a mission extension, and next month the science team will send the spacecraft into Jupiter’s atmosphere, where it will burn up. We will then have to wait five years for Europa Clipper to arrive in Jupiter orbit, followed a year later by Europe’s Juice orbiter.
While the propaganda press is condemning this decision, there is some logic to it. Juno has mostly completed its work. While new knowledge can certainly be gained if it remained operations for three more years, the amount of knowledge will be relatively small. And NASA does face a budget crunch. Better to spend its money on other things that can produce more bang to the buck.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
Though previous observations had detected auroras on Jupiter produced by three of its four Galilean moons — Io, Europa, and Ganymede — scientists had until now been unable to detect a similar aurora produced by the fourth, Callisto.
The Jupiter orbiter Juno finally accomplished this observation for the first time.
[T]o image Callisto’s footprint, the main auroral oval needs to move aside while the polar region is being imaged. And to bring to bear Juno’s arsenal of instruments studying fields and particles, the spacecraft’s trajectory must carry it across the magnetic field line linking Callisto and Jupiter.
These two events serendipitously occurred during Juno’s 22nd orbit of the giant planet, in September 2019, revealing Callisto’s auroral footprint and providing a sample of the particle population, electromagnetic waves, and magnetic fields associated with the interaction.
The research paper describing this detection has just been published.
These secondary auroras are caused by Jupiter’s powerful magnetic field.
The Juno mission itself is about to end. NASA did not approve a mission extension, and next month the science team will send the spacecraft into Jupiter’s atmosphere, where it will burn up. We will then have to wait five years for Europa Clipper to arrive in Jupiter orbit, followed a year later by Europe’s Juice orbiter.
While the propaganda press is condemning this decision, there is some logic to it. Juno has mostly completed its work. While new knowledge can certainly be gained if it remained operations for three more years, the amount of knowledge will be relatively small. And NASA does face a budget crunch. Better to spend its money on other things that can produce more bang to the buck.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon or from any other book seller. If you want an autographed copy the price is $60 for the hardback and $45 for the paperback, plus $8 shipping for each. Go here for purchasing details. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
If it doomed then why not have a razz at firing it’s engines up and going to have a look at our interstellar comet visitor? Is there any downside apart from failure if it doesn’t work? ( Planetary protection? )… It seems such a waste to send a well functioning spacecraft at a remarkable distance from earth to a fiery, unnecessary death.
But what, exactly, will provide “more bang for the buck”? Given the cost of getting Juno to Jupiter in the first place, it is hard to envision anything else that could possibly be as cost effective as using a paid for system that is already on site and working. Not having seen the actual numbers behind NASA’s decision not to approve a Juno mission extension, it is hard to judge whether this is an example of being penny wise and pound foolish, or if there are truly significant cost savings here that can be better used elsewhere. What is actually being “saved” by shutting the program down?
Aside from the dollars involved, it seems to me that there is also an “opportunity cost” — or would that be a “lost opportunity” cost — in terms of ending Juno’s mission. As Robert puts it, “While new knowledge can certainly be gained if it remained operations for three more years, the amount of knowledge will be relatively small.”* Or, in other words, how cost effective might it be to secure this new knowledge? But what if (yes, I know, some folks HATE what ifs) something were to occur in the Jovian system like the Shoemaker-Levy cometary impact in 1984? In such a case, what is the “cost” of *not* having Juno there? Likewise, the years long gap in the close-up monitoring of the Jovian system until the arrival of Europa Clipper and Juice. What is the price / value of continuity?
*Following a similar line of reasoning, when will it be “time” to shut down the Mars rovers Curiosity and Perseverance? When will it not be “worth it” to keep them going?
Finally, I like Jay’s idea, and clickbait prone sloppy thinker that I am, I would like to learn more about 3I/ATLAS even if it turns out to be nothing more than a “normal” comet from another solar system. Here, the cost to benefit ratio / bang for the buck would seem to be very high indeed if Juno can be repurposed, and the cost of failure (should Juno explode) would be trivial.