How Jupiter Shocked NASA Scientists | Juno Spacecraft 3-Year Update

I don't know where the time has gone, but it's been 3

year

s since Juno arrived at Jupiter. During this time, she has been collecting valuable and revealing data about the largest of our neighboring planets. She has recently completed Perijove 21, or her 21st polar orbit, out of a total of 35 planned orbits, meaning we are already well over halfway through this mission. Some of you veterans of this channel may remember the video I made about Juno back in her freshman

year

, but what has she discovered since then? Has it disproved some of the assumptions we had about Jupiter before its arrival?

I'm Alex McColgan and you're watching Astrum, and together we'll go over everything Juno has discovered and seen around Jupiter so far. There was some skepticism about whether Juno would last that long, due to the intense radiation around the planet, but Juno is currently in good health. Its polar orbit takes it very close to the planet, just 4,000 km above its atmosphere, meaning it avoids most, but not all, of Jupiter's plasma torus, or this region of extremely energized particles, particles that have trapped in place by Jupiter's powerful magnetic field. field. But fortunately, Juno quickly discovered that the radiation where it orbits was much weaker than initially expected.

This means that even the camera, which was one of the first instruments expected to be, is still operational. Juno completely surprised

scientists

by also discovering another, small, less powerful radiation belt just above the equator, which closely hugs the planet. The mechanisms behind this radiation belt are currently unknown. However, although the radiation exposure has not been as bad as

scientists

expected, due to the nature of Juno's orbit, each passing Perijove takes it further and further into the main radiation belt, meaning Juno will certainly cannot last forever, and Perijove 35 It is currently that mission controllers believe that the mission will be forced to end, after which they will crash Juno into Jupiter to avoid future collisions with Europa.

The charged particles in the plasma torus come particularly from the volcanic activity of Jupiter's closest large moon, Io, which launches particles into Jupiter's orbit. Just to give you an idea of ​​how volcanically active Io is, this was New Horizons' view of Io as it passed Jupiter on its way to Pluto, with the Tvashtar volcano fully erupting. Juno has also observed Io in the infrared, the hot spots that indicate where volcanic activity occurs. Io ejects a ton of particles per second into Jupiter's orbit. As Io travels through the plasma torus and interacts with Jupiter's magnetosphere, this causes a flux tube to exist between the planet and the moon, a flux tube that is an electrical current that travels along a cylindrical tube of magnetic field lines.

Is very powerful; It can develop up to 400,000 volts and between one million and five million amperes of current. Juno was able to obtain very accurate readings of the flux tube during its twelfth orbit, while passing directly through it. No, this did not fry the

spacecraft

, as the flow tube has a large diameter and is therefore not concentrated enough to damage the

spacecraft

. Plus, Juno was in and out in a matter of seconds. Juno is a huge spacecraft, 20 meters in diameter. And it really has to be, since it is a solar-powered spacecraft and only receives 4% of the Sun it would receive around Earth.

This means that although these panels are huge, they can only generate just over 400 watts. But you'll also notice that this design, combined with the fact that Juno spins, makes it look a bit like a fidget spinner. It's not just about making a nice spaceship that rotates. Juno was specifically designed to detect various fields and particles around Jupiter, and having a spacecraft with a large turning radius helps with that. This is particularly evident with this instrument here, the magnetometer at the end of one of the solar panels, tasked with mapping Jupiter's magnetic field. Thanks to Juno's data, we now have a very detailed map of Jupiter's magnetic field that becomes more precise with each passing orbit.

As expected, Juno confirmed that Jupiter has a dipole-like magnetic field, although it is not closely aligned with the axis of rotation. However, what was very interesting is that scientists discovered something called the Great Blue Spot, a region of Jupiter where the magnetic field is very concentrated. Comparing Juno's magnetic field data with previous missions to Jupiter, such as Pioneer, Voyager and Galileo, has also revealed a first in the solar system. The structure of Jupiter's magnetic field has been found to change very gradually over time, called secular variation. Interestingly, this was most evident around Jupiter's Great Blue Spot.

This variation is thought to be driven by a region right at the base of Jupiter's atmosphere, which we'll get to in a moment. Thanks to the combination of the powerful magnetic field and charged particles of the plasma toroid, Jupiter has the brightest aurora in the solar system, with a radiant power of 100 terawatts. Like Earth, auroras appear as bands around the north and south poles, but unlike Earth, these auroras are visible primarily in the ultraviolet and are produced primarily from alternating currents, not direct currents. When Juno measured the energy generated by direct currents in Jupiter's magnetosphere, it was not enough to explain the brightness of the aurora, leading scientists to speculate that the rest of the energy comes from alternating currents.

At this time, it is believed that these alternating currents occur due to turbulence in the magnetic field. Especially at the north pole, the magnetic field lines are much more complex, which interferes with the direct flow of currents. This is evident when comparing the auroras of the North and South Pole, in the North the aurora is much more dispersed, looking more like filaments and flares, while at the South Pole, where the magnetic field lines are softer, the aurora appears be more structured and round. What you will also notice is this bright spot and its tail in the aurora.

This is visibly where Io's flux tube meets the planet. However, what is a little less obvious are these other points. These are from the other large moons of the Jovian system, Europa and Ganymede. So while they are not as powerful as Io's flux tube, these other moons also have their own flux tubes that connect them to the planet. Jupiter's magnetic field leads us nicely to one of Juno's main scientific goals: discovering Jupiter's interior. Since Juno arrived, previous theories have had to be completely ruled out by the data she has collected. Previously it was thought that there was a solid core, but then there was a very sharp cut line between the core and the next layer, the metallic hydrogen layer.

The cloud layer was then thought to be only a few hundred kilometers deep at most. But according to Juno data, Jupiter's atmosphere extends up to 3,000 km deep, and beneath it is an ocean of metallic hydrogen that reaches to the center, and even if there is a core, it is very fuzzy and potentially mixed. with the metallic hydrogen layer. So actually calling Jupiter a gas giant is a bit disingenuous, as it is now believed that 80-90% of its radius is liquid, or technically an electrically conductive plasma, perhaps similar in appearance to liquid mercury. Here, the pressure is so great that the hydrogen does not retain its molecular structure with 2 protons and electrons combined, but rather they separate, meaning that the positive and negative charges can move, becoming an electrically conductive substance.

We claim to believe, as we have not yet been able to recreate metallic hydrogen under laboratory conditions, the pressure needed is millions of times greater than Earth's atmospheric pressure. Although we assume that this must be the case, due to Jupiter's powerful magnetic field. To create a magnetic field of this intensity, the dynamo must originate from an electrically conductive substance. It can't be a denser metal like iron at Earth's core, because Jupiter doesn't have the density for that. In fact, based on its density, we know that it must be composed primarily of hydrogen and smaller amounts of helium, very similar in composition to that of the Sun.

Another factor that influences the strength of the magnetic field is due to the rapid rotation of Jupiter . A day on Jupiter only lasts about 10 hours. Various forces agitate the liquid, generating the dynamo. It is the rotation of the magnetic field from which we can measure a day on Jupiter, since simply observing the visible bands of Jupiter could not give a definitive result, and this is the reason. You will notice that these bands look very peculiar, moving in opposite directions from each other and at different speeds. But this is not so unusual if you also consider the invisible jet streams on Earth.

However, what is surprising is the colors and turbulence found in these bands, so let's try to understand what is happening by examining these images of Juno. The cloud layer you are seeing here is the ammonia cloud layer. Some are white and represent recent clouds that probably rose recently from the deeper parts of the atmosphere. On the other hand, although the red colors you see are also ammonia clouds, these clouds have interacted with ultraviolet light from the Sun. Think of it as photochemical fog, the reddish fog you see in summer in big cities. The coloring substance is not known exactly, but simply put, the longer it is exposed to the sun, the redder it becomes.

Interestingly though, when comparing these bands to what you see on the poles, you'll notice that it's much bluer here. This could be because UV light doesn't reach here as easily compared to the equator. If you look closely, you will also notice what are known as emerging clouds. Initially, it was thought that they might be water ice clouds, but they could also be ammonia clouds. They are potentially the precursors to thunderstorms on Jupiter. The radio wave instrument aboard Juno detects lightning strikes at Jupiter; However, curiously these storms are more located towards the poles than at the equator, and more towards the North Pole than towards the South Pole.

The cause of this is also unknown. When looking closely at Jupiter, it would be difficult not to notice the impressive vortexes and storms that pass through the planet. Juno has had the opportunity to orbit directly above the Great Red Spot, where it discovered something very interesting. The Great Red Spot was known to rise far above the cloud layer, but what scientists didn't expect is how deeply it penetrates Jupiter's atmosphere. The instrument aboard Juno designed to observe the atmosphere has a range of 350 km, and it appears that the Great Red Spot extends even further. Also interesting is that the spot is colder than the surrounding area up to a depth of 80 km, and beyond that it actually becomes warmer than the surrounding area, this heat perhaps driving the storm.

The Great Red Spot has been theorized to be a permanent feature of Jupiter, but so far we've only had about 400 years to observe it, a mere blink on astronomical time scales. Looking over the poles, other possibly permanent features have been observed. Unlike Saturn, which has a hexagon at one pole and a single vortex at the other, Jupiter has five vortices around the south pole and eight around the north. It's hard to say exactly how permanent these storms are, since Juno has only been there for three years - Juno was the first time we really got a good look at Jupiter's poles - but they've been reasonably constant throughout that time.

It is believed that beneath the ammonia cloud layer is a water ice cloud layer, although this has not yet been confirmed because this layer has not yet been seen. However, this is one of Juno's scientific goals, and it has several microwave detectors to try to find this elusive substance. Jupiter generates heat from its interior, which can be seen through an infrared camera; The denser parts of the cloud layer prevent some of this heat from being visible. Similarly, Jupiter also emits microwaves, which the water clouds were hypothesized to absorb. So in theory, Juno should be able to detect where water is present in Jupiter's atmosphere by looking for where Jupiter's microwaves are not visible, although this data has not been published or anything has been found yet.

All that said, Juno still has a lot of time left on this mission, and the data it collects will no doubt be scrutinized in the years to come. Our understanding of Jupiter is gradually increasing, and with this knowledge comes a better understanding of how our solar system, and also that of other solar systems with Jupiter-sized worlds, formed. And who knows,maybe Juno will surprise us a few more times! Do you want to know more about the mechanics behind missions like these, but think they might be too difficult or even too boring? Well, it doesn't have to be that way!

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