Name: 美國宇航局這臺堅不可摧的相機揭示了木星上隱藏的圖案 (This Indestructible NASA Camera Revealed Hidden Patterns on Jupiter)
Uploaded: 2021-01-14T10:38:14.000Z
Duration: 7 min 14 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

Here's this planet with all these incredible storms going on. It's that awe when you're

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confronted with something that's completely natural, no human had any hand in it. I think

it gives you a sense of the power of nature. One of the most resourceful digital cameras

to ever travel beyond Earth is capturing hidden regions on Jupiter for the first time. To

get these photos, engineers had to build a nearly indestructible camera that could

survive in one of the harshest environments in our solar system.

You're looking at the closest image of the Great Red Spot ever taken. Snapped by JunoCam, a deceptively

small camera aboard this NASA probe. It was launched in 2011 and has been orbiting Jupiter

since 2016 with a special purpose: to share previously unseen regions of Jupiter and connect

humanity with its celestial neighbor. The person who is now the principal investigator

on Juno, Scott Bolton was convinced that we should not fly a spacecraft to Juno without

a camera. He enlisted me then to help him get a camera on this spacecraft. But because

there was no need for a science investigation JunoCam turned into an outreach camera.

It would become the eyes for NASA and the world, as we ventured closer to Jupiter than all

previous missions. But because of its role as an outreach tool, resources were limited.

The more challenging side was that the camera was really kind of left with what was a rather

constrained set of resources. Because the science instruments needed mass, power, volume.

And as a result, we were not able to put a big telescope on the front. If you look at

other missions that have flown by or orbited Jupiter, one of the things they all have in

common is they have substantial telescopes. And we just knew that was out of question.

So the team went to the drawing board with a few specific requirements for the camera.

We want to take a picture over the poles. We are not going to be able to build up a mosaic

of images, we have to capture the entire pole in one image and we want it to be colored.

Red, green, blue. And we don't want it to be too murky, there's not a lot of sunlight

at the poles. I also knew at that time that Juno was going to be a spinning spacecraft.

Juno's constant rotation ensures stability during the journey and guarantees that the scientific

instruments aboard are in the best position to observe Jupiter. Plus, they had to plan

for the unforgiving environment. Jupiter has a very powerful magnetic field. There's a

lot of charged particles, electrons, protons, heavier ions. And those can damage electronic

detectors, and they can turn lenses brown, and there's a lot of consequences. So we had

to protect the camera from all of that. At the end of the design and construction stage,

the team built a camera called a push frame imager. What that means is only a little

bit of the planet is imaged at any given instant in time. The field of view is quite wide.

It's 58 degrees, which is very unusual for the typical kinds of cameras that you put

on spacecraft. The camera, however, isn't snapping pictures at every moment. The spacecraft

is in a 53 day orbit, so it's very elliptical and the spacecraft spends most of its time

very distant from Jupiter. But every 53 days it comes in close and we first fly over the

North pole, two hours later the spacecraft is passing the South pole and as we go by

our closest approach we're just really just skimming the cloud tops. We're so close Jupiter's

in our face where not only do you see the storm, you see the context of the storm, and

you see the winds around the storms. Only when JunoCam is traveling through this small

window of time does it finally get to work. As the spacecraft is rotating the reflected sunlight

off of Jupiter comes down the optics, goes through one of those color filters, and then

it gets turned into these levels of gray. That all gets stored onboard the spacecraft

as a series of ones and zeros and then it gets transmitted from the spacecraft memory

to Earth using radio waves. And then the bytes are turned into lines of an image. So it's

like you've got Jupiter, you turn it into a jigsaw puzzle, and then you put the puzzle

back together again on Earth. We do not have a classic imaging science team

and we count on the public to be our virtual imaging team.

This is where citizens from all over the world step in to process the images that

JunoCam takes. We have the super expert folks that want to start with the raw data and then

we have people who want to pull an image into Photoshop and they might change the color

balance or they might exaggerate the color. I mean it's as limitless as people's imaginations.

And while the camera was originally intended to increase public engagement, it turns out

that you could do really very interesting science with our little outreach camera.

No spacecraft had ever imaged the polar regions, because most spacecraft stay in the equatorial

zone and the first thing we discovered are that there are cyclones around the poles. We're

studying the atmospheric circulation and it turns out these structures are very stable. So

that's teaching us about the circulation patterns around the pole, how deep they go

and how the polar regions link dynamically speaking to the lower latitudes

So little by little, the data's being analyzed scientifically and the papers are being written.

If you look at Jupiter through a telescope it's kind of pastel. It's kind of a yellowish,

but very subtle colors. With the public's help, JunoCam images have shaken up conventional

wisdom around what Jupiter looks like. You put that in the hands of an artist, and suddenly

it's deep blues, and dark browns and everything that you see in those images is there.

But when the color is exaggerated, it's like you're getting punched in the nose with it.

Right now our mission is scheduled to come to an end somewhere in 2021, but because all of

the instruments are doing well and the spacecraft is doing well in Jupiter's radiation environment,

we're starting to look at how to extend the mission. We'll see how long it goes, but right