Jump Shadowing/Masking

[Condottiere]

I've lost the thread when it comes to the ship's computer aspect.

In Mongoose, it takes up no space.

 

[Sigtrygg]

And the computers that do the calculations are Earth based supercomputers, not a few chips on the robot itself.

Nope. Normal computers at most. They're really not that complicated.
(how do you think NASA managed to send probes to Mars and the outer planets in the 1970s? How do you think the Soviets landed on Venus in the 1980s? "Supercomputers" weren't needed for that. You can do the calculations in Excel, for crying out loud. Heck, the dynamicists probably used slide rules in the 60s and 70s).

That room full of people and computers must be for show then - what a waste of money...

 

[Jeff Hopper]

Guys? You do not have to concern yourself with gravitons as long as you view gravity as a measure of the curvature of space-time around a mass. You do not have to transmit anything as long as you take that into account.

All that graviton crap belongs in the same trash heap as tachyons and Shawn Driscoll's trolling.

 

[fusor]

That room full of people and computers must be for show then - what a waste of money...

Maybe everyone needs to read this before continuing to go on about computers: http://history.nasa.gov/computers/Ch8-3.html

 

[rust2]

I think it is time now to declare this thread a desaster zone. See you all somewhere else. :arrow:

 

[legozhodani]

It crashed a while ago, but I kept on reading .

 

[phavoc]

Do you take the time to read what you type? Or do you just HAVE to be right all the time with your smug opinions that you blithely move past what people are saying? But hey, let's go with your example here. Using your description of orbital mechanics as being very predictable, let's add a few more variables. Gravitation of a body is a known variable, let's use Mars for an example. Atmospheric drag is a knownvariable, let's use Mars again. And math. Math is a known variable, too, right?

Now, let's put all those together and let's use math and science to launch a space probe to Mars from Earth. Still with me? Okay. Now, let's throw in some really smart people, let's call them Rocket Scientists, and let's have them be employed by places like JPL, and Lockheed Martin and NASA. Whee! We've got a rocket ship traveling to Mars now!!! And let's say we get there in one piece. Let's, oh, I dunno, let's call our theoretical rocket payload the Mars Climate Orbiter. Everybody knows that pounds-seconds and newton-seconds are different, right? Oh, and toss in the fact that this discrepancy was spotted by humans, but dismissed by other humans. Now do tell me what happens when you feed pounds-seconds data to a program that is operates your thrusters and it is expecting the data to be in newton-seconds? It would be pretty ridiculous to expect such really smart people to make an error that is taught to every child who learns basic science and math, that when you have two different systems you have to convert one to the other in order for it to properly be able to be interpreted correctly. Really smart people like rocket scientists are taught that lesson over and over and over, because, yanno, math!

Tell me how ridiculous that sounds please. Like this couldn't happen?

Yeah, thought so.

Both are utterly unrelated points.

The orbits of an object can be stored in six variables. Yes, six. All the orbital data for every object known in the solar system wouldn't even take up more than a few megabytes of storage at most. Certainly not "petabytes".

What happened with MRO was an idiotic mistake born from budget cuts and human error. It's nothing to do with knowing where Mars is.

Yeah, not so much when you look at the thread.

It WAS a stupid mistake. A very HUMAN error. And it points out that regardless of how the orbits are stored, people can still override it because they know better. I guess you, too, are being overly dismissive of the human part of the science equation? For all our vaunted technology we can still make very stupid, very predictable errors.

And you are still missing the point of storing data you'll most likely never, ever need. Plus the fact that every time we've been able to create more storage space we find new ways to fill it up. So those six variables (and which ones of the many are you going to store? only the orbital mechanics side to predict location?) You don't think they would also store all the environmental data, radiation fields, known orbital hazards, known atmospheric conditions, etc, etc? If they can store it, they will. Just look at how many data points there are for flying approaches into an airport. They'd store it all and then some. Plus you'd get things like visual data stored in video format. Why? Cause they can. Hence your simple six variables would rapidly be expanded to thousands of variables. This is, after all, flight data and if you are going to be arriving from outside the system you need to be able to plot exactly where all the known bodies in the local system are for where you hope to emerge. Which is why any sane navigator (and anyone hoping to have their spaceship retain it's insurance) would download the latest astrographic data of the system they are traveling to whenever possible.

 

[Tenacious-Techhunter]

Absolute bull.
The data alone takes up terrabytes. And that is for normal space - take into account multi-dimensional hyperspacial factors and instead of integrating 6 dimensions you are looking at 12 minimum, probably more.

No... no it doesn’t. N-Body Problems are solved as a function of the number of objects you need to track at a given moment. And when it comes to jump vectors, you mostly only have to concern yourself with the things that are going to pull you out of Jump Space, or meaningfully affect the trajectories of those bodies. Anything smaller than that, or too out of the way to matter, can be simply disregarded. The problem has a “big O notation” of O(n^2), but, for practical problems, this can often be lowered to O(n * ln ). It’s a realistic problem with realistic limitations; it’s not magic that requires a nonsensically large computer.

 

[mancerbear]

I'm going to ask one last time. Please don't ignore me. If you want to talk computers, create your own thread. Please stop hijacking mine to follow your own agenda.

 

[Tenacious-Techhunter]

Well, Mongoose Traveller 1E still had unnecessarily oversized computers and cockpits, so you’re the one that’s less informed.

Again bull.
The computer in even a smallcraft is running artificial gravity, acceleration compensators, a gigawatt fusion power plant, avionics, environmental control and possibly minecraft all at the same time.
How big are the computers that run a boomer? Or a CVN? And by run I do not mean the tablet interface but the actual server racks etc.

Here's a thought - why don't you tell the F35 designers that they can solve all of their issued with its computer issues by just pugging in a toasters worth of raspberry-pi boards.?

Uh... they pretty much do. The ALIS is laptop-sized.

 

[Tenacious-Techhunter]

Why in the world would you want to remain in the elliptical plane if you could avoid doing so? If your destination is on the far side of the system, and even if it is not, it's far better to travel above or below so that you can avoid the vast majority of spatial objects that are IN the elliptical plane. Every system will be different, of course, but there's no real disadvantage from staying away from it whenever possible.

If your destination object is in the other half of the system, and isn’t Jump Shadowed by the star, then, as approach angle allows, yes, you can gain an advantage by avoiding the orbital plane. Those are a lot of “If”s.

If, instead, the planet is Jump Shadowed, being in the orbital plane means, with a well-considered Jump Trajectory, you can take advantage of local gravitational effects to pull on your Brachistochrone trajectory to get you to your destination faster.

And what do you mean about saving "a lot of time" in the destination system? If you arrive at 100D above, at, below or anywhere from your target, your travel time to the planetary surface remains the same. That 100D is a sphere, ergo you are equidistant to your objective wherever you arrive. And with even a minimal 1G capability, the fact that your arrival destination is on the opposite side of the planet is trivlal from a time perspective.

You don’t always land 100D above your target; sometimes, it’s 100D above the target’s star, or 100D above an object eclipsing your target from any reasonable trajectory. Exploiting local gravity can have benefits to get you to your target faster. Sometimes it may matter.

You bring up some valid points, but if anyone disagrees with you then they are wrong and you have to PROVE them wrong. Except that you can't. Why? Because we are discussing a game set in the 52nd century that is only loosely based on real science. Maybe you have missed the sci-fi RPG label it gets? Sci-fi, for your edification, means science fiction. Ergo there is BOTH science AND fiction present in the gaming setting. Emphasis on gaming.

No. You don’t get to invalidate physics just because it’s Science Fiction; you only get to amend them. Half-baked bull@^*% that doesn’t correspond to a combination of actual physics and the setting’s amendments to those physics is not defensible. Period.

You still don't want to get it here, do you? Ships aren't going to have star charts of every single system known simply because they have the petabytes to store the data. If that was the case then why don't commercial pilots carry maps and landing information for every major airport in the world in their flight bags on their iPads? Why? Because a guy flying the NYC - London route doesn't need to know the approach pattern to Narita. To CDG, or Belfast or even Frankfurt am Main, sure, but not Narita. The same logic would be used in the future. Even with virtually unlimited storage, people are going to start finding ways of filling that space up. Hell, cat videos in the future will number in the quintillions probably, and I bet they will use space in their prodigious memory banks for those before they'll store the orbital information for all significant planetary bodies in the known universe.

Your argument is wrong on so many points... first, you say they have data on the system that is 10 years out of date, which is just about as good as current data... Now, you want to move the goalpost to not having that data at all... Fine. We can, today, observe data corresponding to the motions of planets in nearby systems... meaning, by virtue of being in a system only nearly adjacent, you now have the position of your Gas Giant. No reason to believe they somehow can’t do that in the future.

Data on planetary terrain is nothing like data on a star system. A Star System is filled with mostly nothing. An airplane needs every little detail on the surface of the planet from point A to point B, just in case. Not even remotely the same thing. A starship can gather that data in situ before making final approach, if necessary; it doesn’t need it in advance.

But, more importantly, why don’t Starships have SD-card sized Zettabyte Drives??? I see no reason to believe they couldn’t have all the supposed data you’re talking about, not that it’s even remotely as much as you think it is...

 

[Tenacious-Techhunter]

And the computers that do the calculations are Earth based supercomputers, not a few chips on the robot itself.

Supercomputers are tasked with finding cost-effective, fuel-conserving trajectories... not convenient ones; those are complicated, and when money spent on cheap computing power saves Millions in fuel, you buy the fancy computer. Your average Trader or Passenger Liner cares more about making another trade or showing off another glorious view than shaving off fuel. “Fuel Savings” has, quite simply, been eliminated as an important criteria for “mission planning” and shipboard operations... there’s no cost justification for spending computational power on it.

 

[fusor]

It WAS a stupid mistake. A very HUMAN error. And it points out that regardless of how the orbits are stored, people can still override it because they know better. I guess you, too, are being overly dismissive of the human part of the science equation? For all our vaunted technology we can still make very stupid, very predictable errors.

It doesn't point that out at all though. That was someone putting in a number in the wrong units in a program. One mistake (due largely to underfunding) doesn't suddenly mean that everything is suspect and that errors are everywhere and likely. And by that point in the future human errors probably wouldn't even be a factor anyway.

And you are still missing the point of storing data you'll most likely never, ever need. Plus the fact that every time we've been able to create more storage space we find new ways to fill it up. So those six variables (and which ones of the many are you going to store? only the orbital mechanics side to predict location?) You don't think they would also store all the environmental data, radiation fields, known orbital hazards, known atmospheric conditions, etc, etc? If they can store it, they will. Just look at how many data points there are for flying approaches into an airport. They'd store it all and then some. Plus you'd get things like visual data stored in video format. Why? Cause they can. Hence your simple six variables would rapidly be expanded to thousands of variables. This is, after all, flight data and if you are going to be arriving from outside the system you need to be able to plot exactly where all the known bodies in the local system are for where you hope to emerge. Which is why any sane navigator (and anyone hoping to have their spaceship retain it's insurance) would download the latest astrographic data of the system they are traveling to whenever possible.

Sure, I'm not saying that there aren't other variables. But the fact remains that you only need six to completely describe on object's orbit - eccentricity, inclination, semimajor axis, longitude of ascending node, argument of periapsis, and mean anomaly. Between all of those you know exactly where an object is in space. Yes, there'd be more variables for atmospheric data and so on, but it's still not a vast amount of extra data - and they'd probably update that as they approached anyway. I doubt that it would bloat too much, certainly not to even a gigabyte level per system. You don't need complex atmospheric models to know how to get through an atmosphere. You don't need to know the location of every single body in a system either.

 

[Tenacious-Techhunter]

And you are still missing the point of storing data you'll most likely never, ever need. Plus the fact that every time we've been able to create more storage space we find new ways to fill it up. So those six variables (and which ones of the many are you going to store? only the orbital mechanics side to predict location?) You don't think they would also store all the environmental data, radiation fields, known orbital hazards, known atmospheric conditions, etc, etc? If they can store it, they will. Just look at how many data points there are for flying approaches into an airport. They'd store it all and then some. Plus you'd get things like visual data stored in video format. Why? Cause they can. Hence your simple six variables would rapidly be expanded to thousands of variables. This is, after all, flight data and if you are going to be arriving from outside the system you need to be able to plot exactly where all the known bodies in the local system are for where you hope to emerge. Which is why any sane navigator (and anyone hoping to have their spaceship retain it's insurance) would download the latest astrographic data of the system they are traveling to whenever possible.

You specified a change in planet location. That is solely a function of those variables. Video data has no relevance for that calculation.

Certainly, there are other hazards necessary for Jump Calculations and other Navigational purposes. Those will likely be vectorized volumetric geometry, just like how topographical features are low data geometry. Not a big deal. The effort you are making to avoid the actual constraints of the problem are mind-boggling.

 

[Condottiere]

It's very likely that astronavigational data gets distributed monthly to neighbouring systems, and starship captains can update their charts when they dock.

 

[Tenacious-Techhunter]

It’s probably also broadcast by narrow beam laser from system to system; the information may be limited by the speed of light, but, so long as that system doesn’t have punks flinging giant space rocks all over the place in order to sew anarchy, that info should be just as good as anything recent. Honestly, any system in which the data can meaningfully change over the course of a few years should probably be considered a yellow zone.

 

[phavoc]

Your argument is wrong on so many points... first, you say they have data on the system that is 10 years out of date, which is just about as good as current data... Now, you want to move the goalpost to not having that data at all... Fine. We can, today, observe data corresponding to the motions of planets in nearby systems... meaning, by virtue of being in a system only nearly adjacent, you now have the position of your Gas Giant. No reason to believe they somehow can’t do that in the future.

Data on planetary terrain is nothing like data on a star system. A Star System is filled with mostly nothing. An airplane needs every little detail on the surface of the planet from point A to point B, just in case. Not even remotely the same thing. A starship can gather that data in situ before making final approach, if necessary; it doesn’t need it in advance.

But, more importantly, why don’t Starships have SD-card sized Zettabyte Drives??? I see no reason to believe they couldn’t have all the supposed data you’re talking about, not that it’s even remotely as much as you think it is...

If you get a data file that you think is current, and it's actually 10yrs out of date, everything in it will be located 10yrs from where you are expecting it. Since planets move, that means it's 10yrs further along it's track than you are expecting it to be when you emerge from jump space. That was the point of the statement you seem to miss. No goal posts moved, just none paid attention to.

Yes, a star system is filled with lots of empty. No argument there. But most likely your destination is going to be inside that nothingness. Which means you have multiple jump shadows to potentially plot around to get to emerge as close as possible to your final destination. Airplanes don't actually need every little detail. Actually they need relatively few details to plot a course. Now, landing and taking off are different, and if you have ever plotted a course then you'll know that when you get closer to landing is when you'll spend a lot of time plotting flight paths (and in some cases, taking off). But getting between A and B in a modern jetliner? You are flying above any ground-basesd object for the most part. So you just need to avoid restricted airspace and storms.

I couldn't tell you why starships don't have SD cards. Probably because they don't need them. And if they did I'm sure they would be a lot of cat video's taking up the space. It's never been a question of couldn't, as the rules state you have essentially unlimited data storage capacity aboard a starship. It's a simple of question of why would you? And unless you've changed basic humanity, you wouldn't because you'd never need them.

@Mancebear - I do hope you have gotten your questions answered.

 

[fusor]

If you get a data file that you think is current, and it's actually 10yrs out of date, everything in it will be located 10yrs from where you are expecting it. Since planets move, that means it's 10yrs further along it's track than you are expecting it to be when you emerge from jump space. That was the point of the statement you seem to miss. No goal posts moved, just none paid attention to.

So you just fast forward the data by 10 years and you know where the planet is now. It's all very predictable. These things simply don't change on that timescale. Maybe if you end up somehow a few thousand years in the future there'd be some cumulative gravitational perturbations that might cause a planet to be a few kilometres away from where the ephemerides say it's supposed to be, but that's about the extent of it.

Yes, a star system is filled with lots of empty. No argument there. But most likely your destination is going to be inside that nothingness. Which means you have multiple jump shadows to potentially plot around to get to emerge as close as possible to your final destination.

The chance of having any jump shadow intersecting a ship's path is very very small (read some of my posts earlier here, I've explained why already). Heck, the chance of even having the jump line go anywhere near the ecliptic plane of the system (where the planets and their jump shadows are) is very small - for example, none of the systems that correspond to real stars on the Travellr map that are within 6pc of Earth are close enough to the solar system's ecliptic to be affected by any of the solar system's planetary jump shadows.

And if they did I'm sure they would be a lot of cat video's taking up the space.

That's a spurious and specious argument. "Cat videos" and other irrelevant files would simply never be allowed to clog up the storage of computers that are essential for flight and operations, period.

 

[Tenacious-Techhunter]

Airplanes don't actually need every little detail. Actually they need relatively few details to plot a course. Now, landing and taking off are different, and if you have ever plotted a course then you'll know that when you get closer to landing is when you'll spend a lot of time plotting flight paths (and in some cases, taking off). But getting between A and B in a modern jetliner? You are flying above any ground-basesd object for the most part. So you just need to avoid restricted airspace and storms.

No, the justification for those iPads with the route information on them is so they have every possible detail they might need in case of an emergency landing; they need every conceivable piece of information they might need to land on some random strip of land they’ve never landed on before; that’s why their data is so intense. There is no comparison to spaceflight operations, which simply don’t have that sort of urgency combined with that sort of complex data.

 

[Tenacious-Techhunter]

Guys? You do not have to concern yourself with gravitons as long as you view gravity as a measure of the curvature of space-time around a mass. You do not have to transmit anything as long as you take that into account.

I have to give credit where credit is due... you had me doubting myself for a minute there... Could I have simply have fallen behind in my understanding of Science, the same way Traveller itself has??? But... that thing you said...

All that graviton crap belongs in the same trash heap as tachyons and Shawn Driscoll's trolling.

Tell that to Neil Degrasse Tyson!

Gravitons are the predominant theory for transmission of gravitation from one body to another.

Stop infecting myself and others with your ignorance! Read a damn book!