Chapter 1: What is the significance of NASA's Juno mission to Jupiter?
Without a doubt, Juno is one of the most important missions that NASA has ever launched. This is a probe that defied the odds, surviving for years past its original mission end date in a region of space that is usually deadly to probes. It is NASA's most distant planetary orbiter, investigating our solar system's largest planet, and what it has learned there
has shaken our understanding of everything we thought we knew about Jupiter. Its formation, its composition, and the mechanisms that give it such a powerful magnetic field But Juno didn't stop there.
Chapter 2: How did Juno survive in Jupiter's harsh environment?
It has investigated Io, Ganymede, and Europa. It has studied auroras and the largest volcanic eruptions we've ever seen in our solar system. And as this incredible probe has reached the conclusion of its extended mission, it's time to ask the question, what has Juno seen? I'm Alex McColgan and you're watching Astrum.
Join me today in this supercut as we explore the discoveries Juno has made around Jupiter over the years. And like all good stories, this is a tale that ends with a twist. So, let's start from the beginning. As far as NASA missions go, Juno is a medium-budget project with total expense that was initially expected to be about $1.1 billion over the course of its mission time.
Now, Juno is a massive spacecraft, 20 meters in diameter, and it really has to be Because unlike previous probes we've sent out that are powered by radioisotope thermoelectric generators, Juno is a solar-powered spacecraft, and it only gets 4% of the sunlight it would do around Earth. This means that even though these panels are huge, it can only generate just above 400 watts.
It was launched on the 5th of August 2011 using an Atlas V rocket. Escaping Earth's atmosphere and entering orbit is one of the most risky parts of the whole mission, but everything went smoothly and less than an hour after liftoff, he was already on an escape trajectory from the Earth. Juno's journey to Jupiter was an interesting one.
as after it escaped Earth's gravity, it headed into deep space. At this point, it did a small burn using its engines and headed straight back to Earth, reaching it two years after it had first launched. You may wonder to yourself, why would they do that? Well, the answer is very clever. When Juno reached Earth again, the gravity of Earth started pulling Juno towards it.
This gravitational influence increased the speed of Juno by over 14,000 km per hour, slingshotting it at top speeds towards Jupiter. This method is more fuel efficient than burning the probe's engines to get there. After a monumental five-year journey spanning 2.8 billion km, Juno entered orbit around Jupiter in 2016.
Its primary mission consisted of 33 polar orbits of the gas giant, at its closest approach flying only 4,200 km above the Jovian atmosphere. Being this close to Jupiter is a big problem as far as delicate scientific instruments go. You see, Jupiter has an extremely powerful radiation belt around the planet, easily powerful enough to fry most electronics.
Do you remember the previous Jupiter probe, Galileo? Galileo faced a number of setbacks due to the damage received by Jupiter's radiation as its orbit went right through the middle of the radiation belt, so mission planners were keen to avoid a repeat of that as much as possible. Being this close to the planet means Juno would go straight through that deadly radiation belt.
This is why the expected mission life of the probe to begin with wasn't over 20 months in orbit. with some instruments not expected to last beyond the first 8-9 months. To try and prolong the inevitable, Juno was surrounded by a 1cm thick layer of titanium to protect the internals from frying.
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Chapter 3: What discoveries has Juno made about Jupiter's atmosphere?
It adopted a perpendicular orbit which brushed over the planet at its closest approach, only 4,200km above Jupiter's atmosphere at its peridrove. and 8.1 million kilometers at its Aperjove. Aperjove is the point of a spacecraft's orbit when it is closest to Jupiter, and an Aperjove is just the opposite. It's the point in an orbit when the spacecraft is furthest away from Jupiter.
Each orbit took 53 days to complete, and NASA's original plan for Juno was for it to complete its 33 orbits by the end of its mission in 2018, with a burn along the way to take Juno into a close 14-day orbit towards the end. However, this burn was later cancelled, as it was deemed safer, so Juno stayed in its longer orbital position until 2021.
For all the worry over Juno's longevity, however, it turned out that there was nothing to worry about, due in part to a surprising discovery Juno made upon entering Jupiter's magnetic field. One of the reasons Juno approached so close to the planet was to avoid Jupiter's powerful radiation belt.
But there is a gap where the planet ends and the radiation belt starts, and Juno threaded the needle to exploit that. There was some concern that Juno would still get a huge dose of radiation from the parts of the radiation belt. It did hit, the radiation was actually 10 times lower than expected in these parts, great for the health of the probe.
This was a stroke of luck, for NASA, for Juno, and for us. Of course, another advantage of the tiny distance from Juno to Jupiter at its closest approach is that we have been able to see Jupiter in unprecedented detail. The first images of Jupiter's poles in particular took people's breath away.
Some even say that scientists would not have even recognized the planet from these images, just no one expected what they saw. What you are looking at here are many cyclones around the South Pole. What is remarkable is that the planet looks so different from what we are used to seeing on Jupiter, namely its large bands. However, in this image, the contrast has been increased to see details.
The natural eye would see something more like this. This image is also a mosaic of several images in order to show daytime on all sides of the planet. The North Pole isn't quite so clear, as it's in winter and some parts of the pole are in constant night.
Juno also has the capability to peer deep into Jupiter's atmosphere using a microwave radiometer, which was designed specifically for this spacecraft. Using it, scientists were able to see the amount of ammonia in the atmosphere. What they didn't expect to see was this band of ammonia around the equator, ammonia being orange in this image.
The pillar drops down from the cloud tops over 350km, the limit of what the MWR can see. Scientists were puzzled by this, as they expected to see an even distribution of ammonia throughout the planet. They thought the gases in the atmosphere would just mix up, or at least stick to the band pattern of the planet. But these results were far from that.
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