Warp navigation

[Khatharr]

So you have yourself a fancy space-boat with a black-box translation drive. You lock in a target relative to your current position, the drive 'spins-up' for some amount of time, then you are translated directly to the target location. You retain your previous inertia. (I'm basically talking about an instant-travel version of the Alcubierre drive from the Interstellar mod.)

Anyway, the topic I want to discuss is the navigational mechanics of using this drive. Let's say you're warping home from another star system, and the relative speed you enter the Sol System with is extreme. Unfortunately, your main thrusters are offline for some reason. We need to use the gravity of celestial objects for thrust in order to put ourselves into LEO for rendezvous with a rescue/repair vessel.

So the simple way to do this would be to use the sun's gravity to bleed off our entry velocity, then warp around the sun a bit more in order to get near Earth velocity, then warp to Earth and do some corrections to get into a proper orbit.

However, there's another major problem that needs dealt with: you have a studio pass for the new Red Dwarf / Firefly crossover that begins filming tomorrow. You don't have enough time to spin the drive up for too many warps!

What is the time-optimal solution for getting to LEO? Limitations include G force on the crew and excessive heat. Your ship can shield itself from a lot of heat and a little gravity, but the precise amounts aren't set in stone.

Basically what I'm curious about is how to find the optimal solution, rather than what is the optimal solution. Transit is instantaneous, but drive spin-up is time consuming, so we want to use the minimum number of jumps.

Any takers?

[K^2]

Interstellar Mod's Warp doesn't work correctly. I am putting together some material to write up a sort of Warp Physics 101 post, which will include details on which warp trajectories are possible, and how it affects momentum of the ship. Some of it is fairly intuitive, and some of it is not. In a nutshell, you can have a warp ship do almost anything you could imagine, but there are only a handful of trajectories that aren't going to waste impossibly huge amounts of energy.

I don't know if there is an optimal solution here. At least, not trivial one-size-fits-all one. But yes, you can use fly-by with warp. You can utilize it slightly more efficiently with warp, because some fly-by trajectories you simply can't enter without warping or using reaction drives. You can also almost always guarantee yourself the next encounter, even when traveling at an escape velocity, so you can chain together fly-bys that you wouldn't otherwise be able to in any reasonable amount of time.

But your first fly-by might as well be by Jupiter. It has sufficient escape velocity to bleed off all of your interstellar speed and become bound to Sol, and it is closer to inner planets than any other gas giant. But you will still be traveling too fast to enter Earth system in one hop. You'll need to do a fly-by of one of the inner planets before doing that. And that's where details are going to start to come in. Relative positions of inner planets will matter. So there isn't really going to be one right answer.

P.S. By the way, if there is more stuff you want addressed in Warp 101, this will probably be a good place to ask.

[pincushionman]

Jupiter, so you can do long aerobraking passes in the low-density high atmospere. Then when your jump cooldown ends, jump to a spot where you can do the exact same thing again. i know you said your ability to jump is time-constrained, but what does that mean? A day between jumps? How fast are you going to begin with?

Edited February 24, 2015 by pincushionman

[Sirrobert]

Jupiter, so you can do long aerobraking passes in the low-density high atmospere. Then when your jump cooldown ends, jump to a spot where you can do the exact same thing again. i know you said your ability to jump is time-constrained, but what does that mean? A day between jumps? How fast are you going to begin with?

I think the point is to find some 'as few jumps as possible' solution, without worrying about specific numbers.

And yea, I think aerobreaking would be the best solution, as it allows very accurate control over end velocity. You could even aerobreak right down to LEO speed, and time your warp in such a way that you warp to the correct spot in LEO at the exact moment your speed is correct. So you probably wouldn't have to worry about losing orbital velocity around Jupiter and falling into the planet

[Khatharr]

I think the point is to find some 'as few jumps as possible' solution, without worrying about specific numbers.

More 'how do you find' rather than 'find'. Hence the lack of numbers or exact figures. That is, mathematically speaking, how would you create a system of equations that can find an optimal or near optimal solution? Nearest distance to any body would be limited by heat and gravity, but apart from that we want to kill off a large relative velocity and replace it with a precise local velocity. The absolute ideal solution would be to warp to some point near Sol that provides the exact necessary force, then once the force has been applied, warp to Earth, where the new velocity vector will result in immediate LEO.

And yea, I think aerobreaking would be the best solution, as it allows very accurate control over end velocity. You could even aerobreak right down to LEO speed, and time your warp in such a way that you warp to the correct spot in LEO at the exact moment your speed is correct. So you probably wouldn't have to worry about losing orbital velocity around Jupiter and falling into the planet

I'm really trying to reason out how to find optimal or near optimal gravitational solutions. Aerobraking could certainly play a role in the practical sense, but what I'm trying to understand is the system of equations that would maximize the efficiency of gravity use.

[Rakaydos]

"Vertical velocity gets burned by gravity, horizontal velocity is yours to keep"

If we're ignoring aerobreaking, wouldnt the best approach be to find the steepest gravity well, and warp to the point as close to it as your ship design allows, such that your momentum is straight up? So, you emerge from interstellar warp in the solar corona and "fall" straight up.

To bend your course to match your target, dont be EXACTLY straight up- the horizontal momentum you'll keep as you bleed the vertical.

[K^2]

Khatharr, it is not possible to slow yourself down against a lone star using warp. Any amount of permutations will conserve energy and momentum.

This is why you have to use restricted n-body dynamics, and brake with fly-bys. That is why you need Jupiter, and why you cannot have a simple formula for all of this.

[einsteiner]

If you can truly warp anywhere you want, you can warp deep into the sun's gravity well such that your velocity points away from the sun, and use its gravity to slow down. When you have the velocity you want you warp out to LEO with just the right velocity to be in a nice, circular orbit.

To find the optimal maneuver you take the final velocity you want minus the velocity you have to find the velocity you need. You warp to the proximity of the sun with sun's gravity pulling toward that dV vector. To do this fast you want to be as close to the sun as possible. If you can survive being right on the surface you will get an acceleration of 274.0 m/s^2, decreasing as you fly "up" away from the sun. Use the time spent flying up to spool up your jump drive. If you need more dV use it to jump back down to the surface of the sun and repeat until you have the velocity you need, then jump to LEO. You can adjust the amount of dV you get per jump by jumping further from the sun. Your crew won't experience any g-forces since you'll be in free-fall the whole time. You're only limited by how close you can get to the sun.

This whole thing obviously violates conservation of energy and momentum, but so does the jump drive.

[K^2]

If you can truly warp anywhere you want, you can warp deep into the sun's gravity well such that your velocity points away from the sun, and use its gravity to slow down.

Nope. Because as you warp around the system, the velocity of your ship changes. Has to do with the way that warp bubble has to adjust to the curvature of space-time around the star, unless you want to waste mad quantities of energy on gravitational wake.

This whole thing obviously violates conservation of energy and momentum, but so does the jump drive.

Again, completely incorrect. Warp does not violate any conservation laws.

[PB666]

Interstellar Mod's Warp doesn't work correctly. I am putting together some material to write up a sort of Warp Physics 101 post, which will include details on which warp trajectories are possible, and how it affects momentum of the ship. Some of it is fairly intuitive, and some of it is not. In a nutshell, you can have a warp ship do almost anything you could imagine, but there are only a handful of trajectories that aren't going to waste impossibly huge amounts of energy.

I don't know if there is an optimal solution here. At least, not trivial one-size-fits-all one. But yes, you can use fly-by with warp. You can utilize it slightly more efficiently with warp, because some fly-by trajectories you simply can't enter without warping or using reaction drives. You can also almost always guarantee yourself the next encounter, even when traveling at an escape velocity, so you can chain together fly-bys that you wouldn't otherwise be able to in any reasonable amount of time.

But your first fly-by might as well be by Jupiter. It has sufficient escape velocity to bleed off all of your interstellar speed and become bound to Sol, and it is closer to inner planets than any other gas giant. But you will still be traveling too fast to enter Earth system in one hop. You'll need to do a fly-by of one of the inner planets before doing that. And that's where details are going to start to come in. Relative positions of inner planets will matter. So there isn't really going to be one right answer.

P.S. By the way, if there is more stuff you want addressed in Warp 101, this will probably be a good place to ask.

So let me get this strait, VP can't collectively accumulate momentum, but we can kill translational KE differences between two stars by warp speed gravity turn around Jupiter?

lol.

The answer to the question: There is no reason to return and warping back for an event has no meaning or value. It is like asking the question if I traveled to the event horizon of a black hole, how could I return to another galaxy in time to play billiard with my greatgreatgreatgreatgreatgreatgreatgreat.........grandson. Of course billiards is a trivial problem compared to surviving the black hole and then getting out. The last message my great......grandson will probably never hear about me: 'well gee I survived this far, oh I hear a hissing sound in the corn'[pop]

Anyone who travels to another system most likely has the technology to convert every observation into a series of transmissible 1s and 0s. If humans figure out a way to traverse the distance it will be a one-way trip.

[K^2]

So let me get this strait, VP can't collectively accumulate momentum, but we can kill translational KE differences between two stars by warp speed gravity turn around Jupiter?

So let me get this straight, I can't fly with these styrofoam wings I've just made, but I can save 15% or more by switching to Geico?

lol

Yeah, that's roughly how much logic you're putting into your posts. Each fly-by operation is performed without warp. Warp merely gets you to the right position to be able to do the necessary fly-by. If you have more kinetic energy than due to coming in from escape trajectory, say, due to relative velocity of the stars, you will need multiple fly-by operations. But yeah. You can have these absorb all of that energy.

When you can actually do at least some basic computations on diagrams involving virtual particle exchange, or when you understand at least the math behind Alcubierre Metric, then you will have the background to actually weigh in on these discussions. As it is, you are talking total nonsense, and you don't even have the prerequisites to realize that much.

[PB666]

So let me get this straight, I can't fly with these styrofoam wings I've just made, but I can save 15% or more by switching to Geico?

lol

Yeah, that's roughly how much logic you're putting into your posts.

You mean like determining how to exit warp when the technology does not exist from a star where jupiter is not even visible, and where the deviation of site on the sun is sufficient to require course adjustments along the way? The failing of logic on your warp theory are much greater than the quantum statistical issues dealing with getting VP to collectively transfer momentum. Quantum theory is tolerant of 'error' just not on a grand scale it does not obviate that it cannot be tricked, tricking it however may be as difficult as warping between two stars. There is at least some tentative support for the VP argument, there is no support for the argument that we can warp a ship or craft its trajectories significantly without traditional sources of dV.

Each fly-by operation is performed without warp.

That was not the premise to the argument, the premise was not to 'respool' up the drives. With the given premise, the answer is always no.

Warp merely gets you to the right position to be able to do the necessary fly-by. If you have more kinetic energy than due to coming in from escape trajectory, say, due to relative velocity of the stars, you will need multiple fly-by operations. But yeah. You can have these absorb all of that energy.

given the atmospheric limits of jupiter and given typical interstellar differences, there is a high probability that the best trajectory around Jupiter has sufficient velocity to escape Sol system. The only way to avoid this is to jump well prior to Jupiter and dissipate some of that energy. In any case you will still have to Jump well prior to adjust course and optimize interplanetary transfers. There is no way, warp all you want or no warp to get the 'evening concert'.

If we just want to ignore physics, the issues with resolution limit of light, time dilation, n-orbital physics. Warp into earths upper atomosphere at a pitch of 20' dewarp with your crew in suspended animation and surrounded by a gel of density 1.5. Put a large heat shield and tolerate g forces of 30 to 40 for a few seconds. and then gently parachute down on the concert stage.

When you can actually do at least some basic computations on diagrams involving virtual particle exchange, or when you understand at least the math behind Alcubierre Metric, then you will have the background to actually weigh in on these discussions. As it is, you are talking total nonsense, and you don't even have the prerequisites to realize that much.

really, I see, so why don't you get your arse over to ESA and show them how to warp a mouse trap (surely a wee little mouse trap would be easy!) under the Philae lander so they can right the sucker. It is not necessary for me to do the VP math to understand quantum uncertainty, it is up to the folks who are promoting the theory that this is what has happened. You are the one claiming that it impossible for VP to carry momentum back into the quantum vacuum, and I am the one saying that we do not know enough about quantum vacuum to be certain that the statement is true. There is probably alot more uncertainty about true vacuum than there is certainty about warping stuff to pinpoint locations from far off stars.

[Khatharr]

Khatharr, it is not possible to slow yourself down against a lone star using warp. Any amount of permutations will conserve energy and momentum.

This is why you have to use restricted n-body dynamics, and brake with fly-bys. That is why you need Jupiter, and why you cannot have a simple formula for all of this.

I think you're not understanding what I'm talking about. I engaged in some hyperbole in the original post. To retcon: I invented the warp drive, and it ignores conservation entirely because it's powered by enriched narrativium and accomplishes instant translation by constructing a 12 dimensional ham sandwich field. IOW: I'm just trying to work out the gravity solution.

"Vertical velocity gets burned by gravity, horizontal velocity is yours to keep"

If we're ignoring aerobreaking, wouldnt the best approach be to find the steepest gravity well, and warp to the point as close to it as your ship design allows, such that your momentum is straight up? So, you emerge from interstellar warp in the solar corona and "fall" straight up.

To bend your course to match your target, dont be EXACTLY straight up- the horizontal momentum you'll keep as you bleed the vertical.

If you can truly warp anywhere you want, you can warp deep into the sun's gravity well such that your velocity points away from the sun, and use its gravity to slow down. When you have the velocity you want you warp out to LEO with just the right velocity to be in a nice, circular orbit.

To find the optimal maneuver you take the final velocity you want minus the velocity you have to find the velocity you need. You warp to the proximity of the sun with sun's gravity pulling toward that dV vector. To do this fast you want to be as close to the sun as possible. If you can survive being right on the surface you will get an acceleration of 274.0 m/s^2, decreasing as you fly "up" away from the sun. Use the time spent flying up to spool up your jump drive. If you need more dV use it to jump back down to the surface of the sun and repeat until you have the velocity you need, then jump to LEO. You can adjust the amount of dV you get per jump by jumping further from the sun. Your crew won't experience any g-forces since you'll be in free-fall the whole time. You're only limited by how close you can get to the sun.

This whole thing obviously violates conservation of energy and momentum, but so does the jump drive.

You two are thinking about what I'm thinking about, but the approach described could have problems because the target is in motion while the gravity maneuver is taking place. (This is where I'm chewing on it.) If the solar gravity maneuver took almost the whole day, for instance, then the Earth will have moved through its orbit by slightly less than a degree, which means that the velocity vector on arrival could be incorrect. A single degree probably isn't a huge hairy deal, but if the target were a faster moving body then the change could be fatal. For instance, if the target were the moon then a single day would include a near 1 degree change from the Earth's orbit as well as a 12 degree change from the moon's orbit. Aditionally, when entering foreign systems, the parent body may be less massive and the maneuvers could take a lot longer, meaning that the target position will have changed more drastically.

What I'm trying to sort out in my mind is: If I set up the maneuver such that it works for the target's current position, then the time the maneuver takes will make it incorrect, but if I calculate that time and then aim for the target's expected position then there's a decent chance that the new maneuver will take a different amount of time and again be incorrect (though probably closer to correct). It seems like there's an in-between solution there that will give a 'correct' solution, but I don't know how to get at that formulaically. There's an absolute minimum distance to the star determined by heat level and gravitation tolerance. Orignially I was thinking that the effect of gravity would be more severe when the craft was moving away faster, but then I actually engaged my brain and realized that the force due to gravity is not affected by relative velocity, but only by distance.

Actually...

Now that I'm thinking about it again, I just realized that the direction of velocity is very nearly irrelevant unless you're aiming for a specific direction of orbit. As long as speed relative to the target body is correct, you can simply warp to the correct position to turn it into a circular orbit. -.-

That being the case, I guess the optimal solution would simply be to warp to the nearest safe position to the parent body that puts it retrograde and then it just becomes a matter of determining how often is the most efficient to warp back to that position rather than simply coasting. Eventually you'll reach the relative speed required and can just translate to the correct orbital position immediately. That approach actually has a decently sized safety-window, as well, because you'll transition through the higher speeds that simply correspond to higher orbits. The only thing to watch out for would be to make sure that you don't pass through the window too near to the parent body, where it may pass too quickly for a precise jump.

Edited February 25, 2015 by Khatharr

[PB666]

If I set up the maneuver such that it works for the target's current position, then the time the maneuver takes will make it incorrect, but if I calculate that time and then aim for the target's expected position then there's a decent chance that the new maneuver will take a different amount of time and again be incorrect (though probably closer to correct). It seems like there's an in-between solution there that will give a 'correct' solution, but I don't know how to get at that formulaically. There's an absolute minimum distance to the star determined by heat level and gravitation tolerance. Orignially I was thinking that the effect of gravity would be more severe when the craft was moving away faster, but then I actually engaged my brain and realized that the force due to gravity is not affected by relative velocity, but only by distance.

Something we don't think about the ham-sandwich drive........the warp field itself may significantly alter n-body physics in the system in which the ship arrives. Jupiter may not like tomatoes on its ham, and prefer an egg-muffin instead. IOW if you craft produces sufficient energy to warp space, what is the reaction of Jupiter going to be when this ship gets close enough for a fly-by.

This whole thought experiments is laced with pot-holes. You'de be better off giving your ship drives with 10000 fold ISP, and kerbals with long lifespans and no food requirements (that is until the girl kerbals show up, that ham sandwich is a gonner when baby kerbals show up) and spending a few years in space getting the right intercepts.

[K^2]

I think you're not understanding what I'm talking about. I engaged in some hyperbole in the original post. To retcon: I invented the warp drive, and it ignores conservation entirely because it's powered by enriched narrativium and accomplishes instant translation by constructing a 12 dimensional ham sandwich field. IOW: I'm just trying to work out the gravity solution.

Such a drive can stop on a spot anywhere it needs to. It doesn't need gravity. Indeed, it ignores it. So if you have enough unicorn horns and pixie dust to power it, the optimal solution is to just warp to wherever you need to be, exiting warp with whatever speed you wish.

That was not the premise to the argument, the premise was not to 'respool' up the drives. With the given premise, the answer is always no.

My interpretation was minimal "respooling", not a single warp. With a single warp, all you can do is aim for the star, pray to whatever gods you worship that your math is right, do the jump, and then use NPP to try and brake while you're still in the star system. Actually, for braking, you might be able to use a Buzzard Ramjet. And if you fail any of the above, you get to drift off into the void.

You mean like determining how to exit warp when the technology does not exist from a star where jupiter is not even visible, and where the deviation of site on the sun is sufficient to require course adjustments along the way? The failing of logic on your warp theory are much greater than the quantum statistical issues dealing with getting VP to collectively transfer momentum. Quantum theory is tolerant of 'error' just not on a grand scale it does not obviate that it cannot be tricked, tricking it however may be as difficult as warping between two stars. There is at least some tentative support for the VP argument, there is no support for the argument that we can warp a ship or craft its trajectories significantly without traditional sources of dV.

Quantum Physics isn't some sort of Voodoo, where you get random errors. It's the most precise field of Physics. Most of Quantum Field Theory is really a branch of Linear Algebra. There are no "errors". No "random fluctuations". You keep talking about virtual particles, but you don't have a first clue what they are. They aren't fairy dust. They are off-the-shell excitations in the fields. As such, they can carry momentum between any two points in space-time, but the effectiveness drops exponentially with distance. The statistical improbability of what you are suggesting has enough zeroes to make scientific notation cumbersome. And you're shaking it like you've got something.

Compared to that, lack of exotic matter or impossibly high energies required for practical FTL warp seem like minor engineering problems. And I don't expect that we'll have FTL warp any time soon. Quite possibly ever. But unlike magic reactionless drives, we understand the physics of warp. We can talk about what WOULD happen if we were able to satisfy the conditions. Even if it forever remains theoretical. Just like we can talk about what WOULD happen if Sun were to go Nova, or what WOULD happen if Earth got knocked out of its orbit, even if we have absolutely zero chance of making it happen.

[Khatharr]

Such a drive can stop on a spot anywhere it needs to. It doesn't need gravity. Indeed, it ignores it. So if you have enough unicorn horns and pixie dust to power it, the optimal solution is to just warp to wherever you need to be, exiting warp with whatever speed you wish.

Except that:

You retain your previous inertia.

Anyway, I'm fairly certain at this point that you're being intentionally obtuse, and I already figured out a workable solution, so I'm gonna go.

Thanks for the conversation, everyone.

[PB666]

My interpretation was minimal "respooling", not a single warp. With a single warp, all you can do is aim for the star, pray to whatever gods you worship that your math is right, do the jump, and then use NPP to try and brake while you're still in the star system. Actually, for braking, you might be able to use a Buzzard Ramjet. And if you fail any of the above, you get to drift off into the void.

This is what I am trying to get at.

Quantum Physics isn't some sort of Voodoo, where you get random errors.

Reductio ad adsurdum! never said that or implied that it was Voodoo. Different from you I don't pretend that I know every interaction with quantum particles. I don't believe their drive can be replicated however I am willing to keep my mind open more so that 'god does not play dice with the universe'. Its essentially the angle you are defending.