Name: Syzygy（プラス軌道と惑星間旅行） - 60のシンボル (Syzygy (plus orbits and interplanetary travel) - Sixty Symbols)
Uploaded: 2021-01-14T10:30:05.000Z
Duration: 16 min 22 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

So this video allows me to work in one of my favorite words in astronomy, which I wanted to put in tow a video for a long time, which is a city.

Good first gravel city in astronomy is a co alignment.

A lining up of three bodies in some sort of gravitational line.

So we're used to this all the time when we have eclipses.

We've got a city of the earth and the sun and the moon, different combinations, depending on which kind of eclipse it is.

And yesterday there was a city in the solar system because the planet Jupiter was in opposition.

And that means it is directly opposite the sun as seen from Earth.

The sun is in one direction, Jupiter's directly opposite, which makes it great for viewing.

And so this made me think, How did we get from one planet to another?

If Jupiter is an opposition, which means it's pretty much just close is gonna get to us.

Wouldn't this be the best time to be sending a mission to Jupiter.

And so what we're gonna explore in this video today is the challenges of moving around the solar system when everything else is in motion and we've got gravity to contend with.

One of my favorite recent Siri's, has been the expanse.

It's, Ah, story that's entirely set in the solar system so that the solar system has been colonized.

The other planets Sini in the asteroid belt, have been colonized.

A riel prominent character in the stories is gravity is the challenges of getting around the solar system, the challenges of growing up and living in lower gravity environments what that means, and particularly the challenges of getting from one place to the other and everything that that involves.

So that's kind of what I wanted to talk about today because, you know, all the graphics that we see of the solar system have planets lined up.

You know, in a line you would see that obviously not to scale and Australia's upside.

How much I like crazy just for you Did that just for you And and even in science fiction that this happens a lot.

You think, right, you're gonna Jupiter and then you go a little further.

So the point is the planets or not, we all know this.

The planets are not arranged in this nice line.

Just because we get to Jupiter doesn't mean that if we go a little further, we get to Saturn because these things are actually orbiting in circles around the sun or lips is.

And you know, Jupiter might be over here in one configuration, and Saturn might be way over here.

I'm sure we could cycle back through the solar system calculator and find lots of sister.

I don't think it's very likely that everything has been in the line, but that would be anything to look for.

Maybe that's where they started really trolling me today.

Okay, so this is a view of where the solar system planets are today, at least the inner solar system starting from Jupiter, Jupiter with its spot there on, then Mars is over here and then because I said that Jupiter is an opposition.

That means that the Earth and the sun and Jupiter in a straight line and then further in you've got Venus and you've got mercury and the inner planets.

The outer planets are moving much more slowly.

So let's imagine now that we just want to get from Earth to Jupiter.

We wouldn't send out a rocket pointed at Jupiter right now, because Jupiter's moving Jupiter's moving slowly, the earth is moving a little bit more quickly, and so what do we d'oh?

The most efficient way to get from one orbit to another is something called ah Hohmann Transfer orbit.

And this is beautiful and simple because all it needs are two impulses to changes of velocity, and that will get you from Earth to orbit eventually to Jupiter's orbit.

It's the most efficient way uses the least amount of fuel, which is obviously going to be a big consideration when you're traveling around the solar system.

That might not be the best way to do it in terms of human passengers and protecting them for radiation, keeping them fed, watered and everything but in terms of pure rocket efficiency.

Now I know from past experience that we've got many viewers out there who are participants in the curb all space program, which is a solar system, simulate.

And I know that when I talk about the home and transfer orbits, the hairs on the back of their neck will be going up and saying, OK, yes, but there's more complicated orbits and there's more things to think about, and that's absolutely true.

This, as many things are in our explanations of physics, is simplified.

Assuming that the two bodies air perfectly in the same plane, it's assuming that they're starting on very circular orbits, and it's neglecting the gravitational effects from other bodies.

That being said, this is how you would get from Earth to Jupiter, using a home and transfer orbit.

All you have to dio is at the right point.

You want to launch your spacecraft from Earth orbit will neglect.

Getting off the earth will seem, were in the same orbit around the sun as the earth is and all you want to do is add velocity in a tangential direction.

So we want to give it an instantaneous boost that way.

What is that gonna d'oh We've known for hundreds of years since Kepler came up with his laws that beautifully described motions of the planets that the planets orbit the sun in elliptical orbits with the sun at one focus.

So if we're starting from a relatively circular orbit here and we add that impulse, we make this into bigger ellipse.

If we do it just right, will then follow an elliptical path.

And if we time it just right, that elliptical orbit will have its furthest distance from the sun.

Its appeal Ian right at the intersection with Jupiter's orbit.

Now we just have to get the timing right.

And so what we have to calculate is when to make that maneuver in order that we catch up with Jupiter and we crossed that orbit.

It's not Earth is going, and we crossed that orbit.

So that's only half the story, though, because if that's all, we d'oh will fall back in on this orbit and will continue back into this nice, elliptical orbit that will cross Earth's orbit at one end and Jupiter's orbit at the other.

And when Space X launched the Tesla Roadster into orbit and said it was going to Mars, this is what it did.

It went into an orbit that took it across the orbit of Mars.

But then it's come back again, and it's gonna be in that Mars earth loop until something else changes it so you can track it.

I found a Web site, so it it is on its way back to Earth's orbit, not to earth.

Just like it didn't get to Mars because Mars wasn't there when it crossed Mars orbit.

It's gonna come back to Earth's orbit, but Earth is gonna be on the other side of the sun.

Well, one of them happened to be there when it will either get back to work, presumably, if it lasts long enough and you forward this infant infinitely.

But what's more likely is that it will be broken up or disturbed or or something.

So we sent our spacecraft on a transfer orbit to Jupiter.

When we get there, if we don't do anything else to the spacecraft, it's just gonna follow this elliptical orbit.

We need to change its velocity again so that we match the orbital speed of Jupiter on.

So that's all you need is to impulses to changes in velocity, one of Earth's orbit, one of Jupiter's orbit tangential to the direction of the planets.

You're gonna change from that lip to Corbett into a nice circular orbit matching what is the impulse when we get to Jupiter's over, When we get to do better, we have to apply another tangential kick in velocity to speed up to match Jupiter's orbital speed.

Now, if you wanted to get into Jupiter's orbit around Jupiter or if you want the land on Jupiter, that would require even more velocity change in terms of rocket trajectories.

We talked about a Delta V budget, so delta is the Greek symbol that we use for change, and Delta V is just the total amount of velocity changes you need to make your maneuver happen.

Forget Jupiter for a minute for trying to land on Mars.

Some of that Delta V could be acquired through aero braking.

If you want to land on a planet, you need to slow down or you're just gonna slam right into it.

字幕リスト動画再生

Syzygy（プラス軌道と惑星間旅行） - 60のシンボル (Syzygy (plus orbits and interplanetary travel) - Sixty Symbols)

assume

absolutely

boost

straight