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The Jedi seem determined to burn thrusters the wrong way and make their situation worse, not that there's any reason a starship should begin to fall from orbit just because part of it gets blown up anyway.
Careful here. Yes, if you are in orbit, in other words, moving around the planet at a velocity and angle which fights/balances the planets gravity towards it's surface, having an engine die means just maintaining you relative distance above the planet continuing to orbit.
However, if you are maintaining a surface geostationary position above the planet using some magical antigravity device while not located in the geostationary orbital plane, once that device is turned off, you will begin to drop like a rock.
It is the same for use here. if we shoot a rocket straight up above the ground to the orbital altitude of our current international space station, once the rocket runs out of fuel, the rocket will decelerate, then begin to drop like a rock as it does not have the angular velocity around the earth to counteract the Earth's gravity.
To stop your rocket which was stationary relative to the ground from falling, it would have to go 35,786 kilometers above the equator where our geostationary satellites are located. That is the one magic altitude above our equator where you just magically stay stationary above the ground below. The altitude of our international space station at 408 kilometers is just way to close and if it were to stay above one point of the Earth relative to the ground, at 408km, it would drop like a rock and without it's current orbital speed, it would not burn up in our atmosphere where most of it would reach the ground.
I know in scifi they always say their ships are in orbit while having/using their impossible magical antigravity drive to be much closer to the planet and still stay above a certain land mass (IE: military point/target of interest) just illustrates the writers using the term 'orbit' to mean something a little different than in our reality.
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The one time Star Wars got the science pretty right
The "wings flying against an atmosphere" dynamics of most of Star Wars action sequences was getting the science pretty much right?
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As David Hess said, Star Wars isn't so much science fiction as space opera. Some of the (many) novels written under license in the period between ROTJ and TPM are decent sci-fi however, and I continue to regard them as "canon" and disregard the questionable (at best) prequels, and have a special contempt for the utter dross from Disney.
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Another one in Star Wars which is very wrong is the orbital mechanics during the crashing of the ship about 20 minutes in to Revenge of the Sith (III, in chronological order). The Jedi seem determined to burn thrusters the wrong way and make their situation worse, not that there's any reason a starship should begin to fall from orbit just because part of it gets blown up anyway.
Star Trek Beyond got that right at least accidentally when Nero is drilling into Vulcan - he was not in inertial orbit. Star Wars ships obviously have some type of anti-gravity and gravity generation, so presumably could maintain a non inertial orbit where loss of power would cause a rapid acceleration toward the planet. Of course it is never explained and is treated more like a ship sinking, but whatever.
Again, Star Wars is space opera and not science fiction, so I would not take it that seriously.
In Babylon 5 the Earth ship crews move around in freefall when the ship is not under acceleration until later ships include rotating sections or later some form of artificial gravity, but in any Hollywood production except most recently The Expanse, having to simulate freefall in many scenes is a large practical problem.
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Geostationary orbit is not a "magical" altitude. Orbital speed in geostationary orbit is a bit over 3 km/sec.
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To stop your rocket which was stationary relative to the ground from falling, it would have to go 35,786 kilometers above the equator where our geostationary satellites are located. That is the one magic altitude above our equator where you just magically stay stationary above the ground below.
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Geostationary orbit is not a "magical" altitude. Orbital speed in geostationary orbit is a bit over 3 km/sec.
You are correct that the altitude I mentioned, to maintain that relative stationary position above the Earth's ground way below, because of the Earth's rotation, you would be traveling at your noted ~3km/sec. And like I said it is an orbit....
To stop your rocket which was stationary relative to the ground from falling, it would have to go 35,786 kilometers above the equator where our geostationary satellites are located. That is the one magic altitude above our equator where you just magically stay stationary above the ground below.
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That's probably what you meant, but not exactly what you said. You said that if you shoot a rocket "straight up" to the altitude of the ISS, it will eventually "drop like a rock", but by going farther up to 35,786 kilometers the rocket will "just magically stay stationary above the ground below". You left out the part about also needing to accelerate tangentially to 3.1 kilometers per second.
It is the same for use here. if we shoot a rocket straight up above the ground to the orbital altitude of our current international space station, once the rocket runs out of fuel, the rocket will decelerate, then begin to drop like a rock as it does not have the angular velocity around the earth to counteract the Earth's gravity.
To stop your rocket which was stationary relative to the ground from falling, it would have to go 35,786 kilometers above the equator where our geostationary satellites are located. That is the one magic altitude above our equator where you just magically stay stationary above the ground below. The altitude of our international space station at 408 kilometers is just way to close and if it were to stay above one point of the Earth relative to the ground, at 408km, it would drop
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Star Wars is not science fiction. It is space opera.
And, IMO, quite bad space opera.
I still recall in my teens going to watch the original "Star Wars" when it came out with great expectations.
I was coming from dozen of sci-fi books (possibly ~100), and 2001, and Solaris, so I just felt I disappointed that I had watched a bad western.
I have also seen the two following movies, more from social pressure than other reasons, and can't remember having enjoyed them.
You want good space opera? Read the Culture series from Iain M. Banks. -
That's probably what you meant, but not exactly what you said. You said that if you shoot a rocket "straight up" to the altitude of the ISS, it will eventually "drop like a rock", but by going farther up to 35,786 kilometers the rocket will "just magically stay stationary above the ground below". You left out the part about also needing to accelerate tangentially to 3.1 kilometers per second.
My meaning 'straight up' as in keeping a relative stationary position above the ground. This means if the ground is rotating, you do have some orbital speed, it's just at low orbits like 408km up, it is not enough to stop you from falling back down like a rock.It is the same for use here. if we shoot a rocket straight up above the ground to the orbital altitude of our current international space station, once the rocket runs out of fuel, the rocket will decelerate, then begin to drop like a rock as it does not have the angular velocity around the earth to counteract the Earth's gravity.
To stop your rocket which was stationary relative to the ground from falling, it would have to go 35,786 kilometers above the equator where our geostationary satellites are located. That is the one magic altitude above our equator where you just magically stay stationary above the ground below. The altitude of our international space station at 408 kilometers is just way to close and if it were to stay above one point of the Earth relative to the ground, at 408km, it would drop
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Star Wars is not science fiction. It is space opera.
And, IMO, quite bad space opera.
I still recall in my teens going to watch the original "Star Wars" when it came out with great expectations.
I was coming from dozen of sci-fi books (possibly ~100), and 2001, and Solaris, so I just felt I disappointed that I had watched a bad western.
I have also seen the two following movies, more from social pressure than other reasons, and can't remember having enjoyed them.
I did not think Star Wars was that bad, for space opera. I had no interest in seeing it but my parents forced me to go. The execution was good.
My list of good science fiction movies and series is awfully short, but there are a few. Most or all never enjoyed general popularity.QuoteYou want good space opera? Read the Culture series from Iain M. Banks.
At the time I was reading a lot of Edgar Rice Burrows, but that became a gateway to hard science fiction.
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I did not think Star Wars was that bad, for space opera. I had no interest in seeing it but my parents forced me to go.
How old were you? I was 17 when it came out and my friends and I waited in line for four hours to see it on opening day. -
My meaning 'straight up' as in keeping a relative stationary position above the ground. This means if the ground is rotating, you do have some orbital speed, it's just at low orbits like 408km up, it is not enough to stop you from falling back down like a rock.
It's not enough at any orbit.
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I did not think Star Wars was that bad, for space opera. I had no interest in seeing it but my parents forced me to go.
How old were you? I was 17 when it came out and my friends and I waited in line for four hours to see it on opening day.
I was 7. I saw it on the large screen at the Orange Cinedome and just got in on the tail end of a line. The theater was completely packed.
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My meaning 'straight up' as in keeping a relative stationary position above the ground. This means if the ground is rotating, you do have some orbital speed, it's just at low orbits like 408km up, it is not enough to stop you from falling back down like a rock.
It's not enough at any orbit.
If you had a 35,786 km tall space-elevator at Earth's equator, and rode it all the way to the top and stepped off, you'd stay where you were relative to the elevator and the ground. (More or less)
This is because the elevator is rotating at 1 RPD (1 revolution per day) with the Earth. ie: The top of the elevator would have an angular velocity of apx 3.07km/sec due to it being affixed to the ground.
Since the the angular velocity of the Earth's rotation at the equator is 465.1m/s, if you launched a rocket straight up (And managed to maintain that angular velocity) you could reach an altitude where 465.1m/s of orbital speed was sufficient to prevent you from reentering Earth's atmosphere. Around 1.84 million Km altitude.. Not sure if this would be a stable Earth orbit due to influences from the Sun and Moon. It would probably end up in solar orbit soon enough.
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That would work. Though I think the elevator would have to be a bit taller to allow for the counterweight.
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If the elevator were tall enough, you could surpass the speed of light. Or could you?
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Since the the angular velocity of the Earth's rotation at the equator is 465.1m/s, if you launched a rocket straight up (And managed to maintain that angular velocity) you could reach an altitude where 465.1m/s of orbital speed was sufficient to prevent you from reentering Earth's atmosphere
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I think your decimal point is in the wrong place.If the elevator were tall enough, you could surpass the speed of light. Or could you?
In theory. At least I think so. In reality probably no material would ever be strong enough and you would have problems with it colliding with the Moon.
After writing that I found a calculator and if I used it right, the height would be a bit over 4 billion kilometers. It would reach out past Pluto. -
Since the the angular velocity of the Earth's rotation at the equator is 465.1m/s, if you launched a rocket straight up (And managed to maintain that angular velocity) you could reach an altitude where 465.1m/s of orbital speed was sufficient to prevent you from reentering Earth's atmosphere
I think your decimal point is in the wrong place.
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There are 86,400 seconds in a day. Therefore at 465.1m/s, a single point on the equator would have moved 40,184,640 meters (40,185 km in 24 hours) which is approximately the circumference of the Earth at the equator.QuoteAfter writing that I found a calculator and if I used it right, the height would be a bit over 4 billion kilometers. It would reach out past Pluto.
Most of these calculators only take a single body into account to keep the math simple. I think you had the Sun selected as the primary SOI instead of the Earth.
Oopps. I see you're talking about the speed of light here...
But you got me thinking... A little research turned up the term Hill Sphere which is basically the highest orbit that could be maintained, at least temporarily, around a body. For the Earth, this is 1.47 million Km, so my theoretical orbit at 1.84 million Km from Earth would be impossible because an object that far from Earth would end up in orbit around the Sun instead of the Earth.
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I've been cracking my head about this for an hour now. It didn't feel right, and this was contrary to the fact what I knew about orbital mechanism. So if you just burn radial out, this doesn't work at all, and you fall back to earth, quite fast. The only way to "carry" your prograde velocity to that high orbit is to add more speed prograde. It's because while you are going to that 1.84M km point, the direction of that vector changes, because you move and the earth moves.My meaning 'straight up' as in keeping a relative stationary position above the ground. This means if the ground is rotating, you do have some orbital speed, it's just at low orbits like 408km up, it is not enough to stop you from falling back down like a rock.
It's not enough at any orbit.
If you had a 35,786 km tall space-elevator at Earth's equator, and rode it all the way to the top and stepped off, you'd stay where you were relative to the elevator and the ground. (More or less)
This is because the elevator is rotating at 1 RPD (1 revolution per day) with the Earth. ie: The top of the elevator would have an angular velocity of apx 3.07km/sec due to it being affixed to the ground.
Since the the angular velocity of the Earth's rotation at the equator is 465.1m/s, if you launched a rocket straight up (And managed to maintain that angular velocity) you could reach an altitude where 465.1m/s of orbital speed was sufficient to prevent you from reentering Earth's atmosphere. Around 1.84 million Km altitude.. Not sure if this would be a stable Earth orbit due to influences from the Sun and Moon. It would probably end up in solar orbit soon enough.
But I'm going to try this tomorrow, because it's an interesting proposition nonetheless. -
So if you just burn radial out, this doesn't work at all, and you fall back to earth, quite fast.
You can, if you reach escape velocity, then you won't fall back to Earth. Less than escape velocity, then yes, you'll fall back.
So as long as you are traveling at more than 11.2 km/s away from Earth, it doesn't matter which direction you are going*. But this is not what we do when launching a satellite which we want to orbit the Earth. Then we need to lean the rocket into a gravity turn to give it horizontal velocity in addition to getting it out of the atmosphere. Ideally a satellite, in a perfectly circular orbit around a perfectly spherical Earth, has zero vertical velocity relative to the surface of the Earth.
* Well, you might come back in a few years if your new solar orbit intersects that of Earth's orbit around the Sun. (That's why Elon's Tesla will pay us a visit sometime in the future) -
You only need to reach a large escape velocity if you want to shut off your engines pretty quickly and never fall back to Earth. If you had the technology to keep your engines going for an extremely long time you could just keep moving gently away from the Earth until its pull on you drops to a value low enough that your modest speed exceeds the much reduced escape velocity at the distance you have achieved. The reason we don't do that is the most efficient way we have to leave the Earth is to get as close to a ballistic launch as possible. i.e. build up speed as fast as we can, and coast.So if you just burn radial out, this doesn't work at all, and you fall back to earth, quite fast.
You can, if you reach escape velocity, then you won't fall back to Earth. Less than escape velocity, then yes, you'll fall back. -
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I think your decimal point is in the wrong place.
Oops. My bad, I was doing everything in km/sec -
Another one to stir the sci-fi pot.
Why do time machines always hold station? That is, they always arrive at exactly the same geodetic location in the past, present and future. Never the true motion of the earth's rotation, orbit, transit and the associated perturbations are taken into consideration. Not even tectonic and erosional elements either.
Marty McFly travelling back to 1955 from 1985 would have arrived ... in the middle of space due to the true motion of the sun around the galaxy. A mere 218 billion kilometres (1457AU) from Hill Valley.
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Another one to stir the sci-fi pot.
Its incredibly hard to make a story flow if you are going to be accurate. Its would be tool long, and too complex. You just have to give the author some licence. How much is appropriate depends on the nature of the tale. For something like Back To The Moneymaking its supposed to be fun, not accurate. I'm much more OK with him jumping to a point on the Earth than with his parents fading away instead of just vanishing as the time lines are supposed to be changing.
Why do time machines always hold station? That is, they always arrive at exactly the same geodetic location in the past, present and future. Never the true motion of the earth's rotation, orbit, transit and the associated perturbations are taken into consideration. Not even tectonic and erosional elements either.
Marty McFly travelling back to 1955 from 1985 would have arrived ... in the middle of space due to the true motion of the sun around the galaxy. A mere 218 billion kilometres (1457AU) from Hill Valley. -
Marty McFly travelling back to 1955 from 1985 would have arrived ... in the middle of space due to the true motion of the sun around the galaxy. A mere 218 billion kilometres (1457AU) from Hill Valley.
They always talked about the flux capacitor which allowed them to move through time. They forgot to mention the flux inductor, which when paired with the flux capacitor, allowed them to move through both space and time in resonance with the universe.