Belts and safe jumping

[rancke]

True, but which one seems to be in some dispute, as indicated by the discussion here.

I keep getting mixed up about what we're discussing. You're talking about the "can you calculate jump solutions ahead of using them?" question, right?

Folk on both sides have become accustomed to a specific interpretation, have evolved their gaming around that interpretation, and are clearly reluctant to abandon long precedent and fondly-remembered history in favor of an alternate interpretation that isn't specifically and unambiguously stated.

Fair enough. And that will last until someone publishes an adventure where it is an important plot point. At which point it becomes fixed. That's how a shared universe evolves.

Marc says there's jump-masking too, and it's become woven into later canon, but there are any number of people who don't include that feature in their otherwise-OTU games. That strikes me as having much broader impact.

It would have a much broader impact if anyone actually paid attention to it. As far as I know, there's not a single official adventure published where the solar jump limit is a feature[*]. The travel rules certainly ignores the additional days and weeks it would take to travel from certain solar jump limits to the life zone around those stars. Likewise they ignore the ramifications of jump masking on travel time.

[*] There may be some system writeups that show the solar jump limit. And I myself has written an adventure set on a world orbiting a Class MV star where the trip from the solar jump limit to the world is a factor, but that was for JTAS Online, so that doean't count.​

Hans

 

[Fritz_Brown]

They have to accept jumping into a system at some considerable distance from the desired planet when that system's sun happens to be between them and the target, or spend some time moving within the origin system if THAT sun happens to be between them and their target system.

This is less true, however, if you jump from out of the elliptic. Yes, there's still some masking going on, but it will be much less than if you try to drive *through* the system (destination or origin). Don't be like Kaaaaaaaaaaaaaaahn!!!!!!

Goodness! Who died and made you moderator?

Don't mind Whipsnade. He's a little grumbly sometimes when you poke him - sort of like a bear hibernating. He does know a lot about this stuff, and is a pretty good guy to listen to, though.

 

[Carlobrand]

I keep getting mixed up about what we're discussing. You're talking about the "can you calculate jump solutions ahead of using them?" question, right?

Well, specifically the issue of whether you can know the duration ahead of the jump. Calculating the solution ahead of use is a part of Book-2, but the folk who prefer to have duration unknown until the instant of jump argue that calculating the solution ahead of time doesn't necessarily mean you know the duration ahead of time and that foreknowledge of duration introduces potential effects not addressed in canon, such as "shopping" for a desired duration.

Fair enough. And that will last until someone publishes an adventure where it is an important plot point. At which point it becomes fixed. That's how a shared universe evolves.

Yep. Makes things kind of interesting sometimes.

It would have a much broader impact if anyone actually paid attention to it. As far as I know, there's not a single official adventure published where the solar jump limit is a feature[*]. The travel rules certainly ignores the additional days and weeks it would take to travel from certain solar jump limits to the life zone around those stars. Likewise they ignore the ramifications of jump masking on travel time.

If they could come up with some simple mechanic that didn't have people guessing and calculating each time, it might be a bit more popular. Maybe some sort of random roll to determine how far from the target planet you'll be, and an addition to the UPP - a fourth digit added to that three-digit data item they added in Spinward Marches Campaign, something that told you if the planet was inside its star's mask zone and, if so, how much longer you'd need to travel to pass through that mask zone to it.

This is less true, however, if you jump from out of the elliptic. Yes, there's still some masking going on, but it will be much less than if you try to drive *through* the system (destination or origin). Don't be like Kaaaaaaaaaaaaaaahn!!!!!!.

How far out of the ecliptic?

If we assume both systems orbit along the same plane - which is admittedly unlikely - then I imagine, for example, Jupiter's jump mask as a circular tube extending 100 Jupiter diameters "north" and "south", and you'd have to move far enough "north" at, say, Barnard to draw a line that took you to Terra without intersecting that tube and then having to give some thought to where Jupiter actually is when you jump (lest you inadvertently precipitate out at Jupiter instead). A line angling from Terra through a point 100 diameters or so north of Jupiter and then through two parsecs of space is likely to run pretty far north of Barnard: figure a worst-case-scenario rise of 7 million kilometers over a run of 630 million kilometers, for 62 trillion kilometers - 700 billion kilometers "north" or "souith" at Barnard? It's probably easier just to let your computer figure out where Jupiter and the rest are than to fly "north" or "south" trying to avoid all the planar obstacles altogether.

Of course, while nearby systems are likely to have similar orbital planes, that doesn't mean they're identical. It's not likely to be as bad as the worst case scenario, but even a simple one-billion kilometer jaunt is going to take you a lot longer than any time you'd save.

Don't mind Whipsnade. He's a little grumbly sometimes when you poke him - sort of like a bear hibernating. He does know a lot about this stuff, and is a pretty good guy to listen to, though.

I've been known to be rather bearish myself on - ahem - rare occasion.

 

[Fritz_Brown]

How far out of the ecliptic?

If we assume both systems orbit along the same plane - which is admittedly unlikely - then I imagine, for example, Jupiter's jump mask as a circular tube extending 100 Jupiter diameters "north" and "south", and you'd have to move far enough "north" at, say, Barnard to draw a line that took you to Terra without intersecting that tube and then having to give some thought to where Jupiter actually is when you jump (lest you inadvertently precipitate out at Jupiter instead). A line angling from Terra through a point 100 diameters or so north of Jupiter and then through two parsecs of space is likely to run pretty far north of Barnard: figure a worst-case-scenario rise of 7 million kilometers over a run of 630 million kilometers, for 62 trillion kilometers - 700 billion kilometers "north" or "souith" at Barnard? It's probably easier just to let your computer figure out where Jupiter and the rest are than to fly "north" or "south" trying to avoid all the planar obstacles altogether.

Of course, while nearby systems are likely to have similar orbital planes, that doesn't mean they're identical. It's not likely to be as bad as the worst case scenario, but even a simple one-billion kilometer jaunt is going to take you a lot longer than any time you'd save.

You're still jumping through the elliptic, in this case. If you start from the worst case scenario* (and assume generally the same elliptic - variations might make it harder or easier) where Earth and the planet to which you wish to jump at Barnard's are on opposite sides of their respective solar masses from each other, you have to drive in n-space to get around the star anyway. So, which is a shorter distance: straight up until you clear the 100d limit of Sol, or drive in the elliptic until you clear the 100d limit AND can avoid all those other rocks and gas balls in the way? The solar mass will generally be your largest 100d limitation if you have to cross to the far side of a system.

Now, in the better case, the planets are between the solar masses, and all you have to avoid are those pesky gas giant orbits and such (oh, and the asteroid belt! just to keep it on topic ). If you drive up out of the elliptic until you clear the largest 100d limit, then you have a straight shot to a similar point at Barnard's. Yes, it means you're unlikely to go 100d-limit to 100d-limit, unless the conditions are just right.

Having said all that, in a well-organized 'verse, there would be standard departure points to various destinations. (Just like in the real world with controlled airports.) You would zip on over to the proper departure point (and a lot of them - but not all - would be "up" out of the elliptic), then you would make your jump - probably to an arrival point at the other end.

To handle procedural control, the arrival points move ever so slightly based on universal time, so people aren't colliding after precipitation. This would be a good explanation for part of the time variance, too. You don't have to make these assumptions or play it this way, but I use it for plot devices. (It's one reason you want to use those pre-plotted courses - the proper ones, not the ones from Vinny's trenchcoat down on the loading dock - because they are constantly updated with all sorts of info on those points and where the planets/stars will be when you jump.)

On the point of things being relative, here's your smile for today: the sky.


* And, you assume jump-masking

 

[Hyphen]

Just out of interest(*), wasn't there a bit of flavour text somewhere in which the protagonist says jump entry was rough, and everyone expected a misjump because the entire crew were throwing up in the 'freshers, but it was only confirmed when the predicted duration passed by, with them still in j-space?

I'e thought for years that's the primary reason for having 4 weeks worth of supplies; just in case you have to start rationing after one week on the hole... ;-)

(*) pours petrol on fire, runs well clear...

 

[Orr]

Just out of interest(*), wasn't there a bit of flavour text somewhere in which the protagonist says jump entry was rough, and everyone expected a misjump because the entire crew were throwing up in the 'freshers, but it was only confirmed when the predicted duration passed by, with them still in j-space?

I think that's from one of the Old Timer sidebars in DGP's SSOM.

Still, stating that jump duration and/or jump exit is predicted doesn't say anything about such a prediction occurring before jump is initiated.

Over 30 years of canon in the form of rules, source books, color text, campaigns, and adventures is clear. You don't know how long a jump will last until you begin it.

Of course that's in the OTU. You can do whatever you want in your own game.

 

[Carlobrand]

You're still jumping through the elliptic, in this case. If you start from the worst case scenario* (and assume generally the same elliptic - variations might make it harder or easier) where Earth and the planet to which you wish to jump at Barnard's are on opposite sides of their respective solar masses from each other, you have to drive in n-space to get around the star anyway. So, which is a shorter distance: straight up until you clear the 100d limit of Sol, or drive in the elliptic until you clear the 100d limit AND can avoid all those other rocks and gas balls in the way? The solar mass will generally be your largest 100d limitation if you have to cross to the far side of a system.

Now, in the better case, the planets are between the solar masses, and all you have to avoid are those pesky gas giant orbits and such (oh, and the asteroid belt! just to keep it on topic ). If you drive up out of the elliptic until you clear the largest 100d limit, then you have a straight shot to a similar point at Barnard's. Yes, it means you're unlikely to go 100d-limit to 100d-limit, unless the conditions are just right.

Having said all that, in a well-organized 'verse, there would be standard departure points to various destinations. (Just like in the real world with controlled airports.) You would zip on over to the proper departure point (and a lot of them - but not all - would be "up" out of the elliptic), then you would make your jump - probably to an arrival point at the other end.

To handle procedural control, the arrival points move ever so slightly based on universal time, so people aren't colliding after precipitation. This would be a good explanation for part of the time variance, too. You don't have to make these assumptions or play it this way, but I use it for plot devices. (It's one reason you want to use those pre-plotted courses - the proper ones, not the ones from Vinny's trenchcoat down on the loading dock - because they are constantly updated with all sorts of info on those points and where the planets/stars will be when you jump.)

On the point of things being relative, here's your smile for today: the sky.


* And, you assume jump-masking

So you're cutting out the angle by going from one point to another high in the ecliptic. Beats all heck out of going billions of miles out of your way to find an angle on the target world itself. Good ol' G2 Sol is, what, 1.4 million kilometers in diameter? 100 diameters, a 140 million klick flight to fly over it rather than around. 2 to 3 days flight. Perhaps a roughly similar flight on the other end if your target circles a similar star. A preferred solution if the target system lies on the other side of Sol on the day you decide to take flight - or if the target world is on the other side of IT'S star. Smaller stars, a bit less, but generally 1 to 3 days out, jump, 1 to 3 days in. I actually like that a lot, very simple. (And, plenty of room for pirates.:devil But ...

Terra, for example: for about a third of the year, you can chart a course from a given neighbor star that takes you within about 10 million klicks, shave two days off your flight time. Still leaves you with the problem of the neighbor star; a good bead on Terra doesn't mean you're in a good position in the neighboring system, might still have to resort to the ecliptic bit for that reason. Still, as you mentioned, there will be windows during which, for a couple of months, you can shave almost a week off your normal-space travel time.

This gets complicated fast, wouldn't even try to calculate that one in-game, probably better just a random roll ("This is your lucky day, there's a window open for the next month!"), but I bet it'd have some real interesting ramifications for trade.

...Over 30 years of canon in the form of rules, source books, color text, campaigns, and adventures is clear. You don't know how long a jump will last until you begin it ...

Still hoping for references.

 

[Fritz_Brown]

(And, plenty of room for pirates.:devil

Uh huh............

This gets complicated fast,....

Which is why you have a 3dT computer to make the calculations.

Interesting, but I don't think I've ever even calculated the time in jump, except once (as a player, never as a referee).

One other plot point helped by using planned departure and arrival points: someone can tell where you're jumping. One of the ... 'discussions' around here at times has been whether you can tell a jump destination when someone jumps. You might or might not be able to discern vector, but you can tell based on which "jump point" they use. Generally. *tosses lit stick of dynamite over transom and runs*

 

[aramis]

Uh huh............



Which is why you have a 3dT computer to make the calculations.

Interesting, but I don't think I've ever even calculated the time in jump, except once (as a player, never as a referee).

One other plot point helped by using planned departure and arrival points: someone can tell where you're jumping. One of the ... 'discussions' around here at times has been whether you can tell a jump destination when someone jumps. You might or might not be able to discern vector, but you can tell based on which "jump point" they use. Generally. *tosses lit stick of dynamite over transom and runs*

Regency Source Book (TNE) says you can figure it out from watching their jump entry transition.

 

[nDervish]

This gets complicated fast, wouldn't even try to calculate that one in-game, probably better just a random roll ("This is your lucky day, there's a window open for the next month!"), but I bet it'd have some real interesting ramifications for trade.

Yep. That's one of the major reasons I choose not to have jump masking IMTU (and not to care if T5 makes masking black-letter canon). It's not feasible to determine the appropriate stellar and planetary alignments and there's no indication in the trade or equipment rules of price fluctuations resulting from shipping delays due to those alignments, so "jump masking" is, so far as I can tell, nothing more than a synonym for "GM fiat" - except that I doubt any GM would be invoking it anywhere nearly as often as the rationale suggests it should come up.

One other plot point helped by using planned departure and arrival points: someone can tell where you're jumping. One of the ... 'discussions' around here at times has been whether you can tell a jump destination when someone jumps. You might or might not be able to discern vector, but you can tell based on which "jump point" they use. Generally. *tosses lit stick of dynamite over transom and runs*

I doubt it's canon, but I've seen it suggested elsewhere online that the jump flash of a departing ship reveals either the direction or the distance (but not both) of its jump. Personally, though, I think invoking jump flash is a little unnecessary if you have ships zero their vector relative to the destination system (which, to me, would make more sense than zeroing it relative to the origin system). Identifying which of the stars within J-6 range match the departing ship's normal-space vector would be trivial.

 

[mike wightman]

Regency Source Book (TNE) says you can figure it out from watching their jump entry transition.

This directly contradicts and therefor overwrites Marc's article - in which it states it is not possible to know where a ship is jumping to.

Because a ship's jump destination cannot be predicted, a microjump within a system still leaves an impression that the ship has left; a week later, it emerges from jump in the same system, to the observer's confusion.

Don't you just love retcons

 

[Fritz_Brown]

*tosses lit stick of dynamite over transom and runs*

Regency Source Book (TNE) says you can figure it out from watching their jump entry transition.

Bwahahahahahah!!!! My work here is done! :toast:

if you have ships zero their vector relative to the destination system (which, to me, would make more sense than zeroing it relative to the origin system).

How do you handle scouting a new system, though? You don't know the full motion of that system?

 

[far-trader]

How do you handle scouting a new system, though? You don't know the full motion of that system?

With some risk of course. You have seen the CT Scout survival rolls right

...granted that really doesn't explain said low survival rates for the fully explored and mapped setting of the OTU Imperium.

 

[Dragoner]

...granted that really doesn't explain said low survival rates for the fully explored and mapped setting of the OTU Imperium.

Unless you factor in all the scoutsicles in out of fuel x-boats...

 

[aramis]

Unless you factor in all the scoutsicles in out of fuel x-boats...

Nah, it's that scouts party like insane frat-boys when on their dirtside time...

"Chug the brew! Chug the brew! Chug, Chug, Chug the brew!"

 

[Dragoner]

Nah, it's that scouts party like insane frat-boys when on their dirtside time...

"Chug the brew! Chug the brew! Chug, Chug, Chug the brew!"

I seem to remember the scouts having their own part of the TAS or something, so that's what goes on there.

 

[nDervish]

How do you handle scouting a new system, though? You don't know the full motion of that system?

I should have been more precise... When I think "relative to [whatever] system", I'm really thinking "relative to that system's primary star". Zeroing your vector relative to the primary star of an unexplored system is just as easy as an explored system, given that we've already got a pretty good handle on the velocities of stars over 6 parsecs from Sol.

 

[Peter Newman]

This directly contradicts and therefor overwrites Marc's article - in which it states it is not possible to know where a ship is jumping to.

Don't you just love retcons

No, it just means that TNE ships, which have less centralized computers to avoid Virus, have more extreme jump flash and therefore you can tell where they're going. OTOH CT era ships, with their more centralized computing systems have less evident jump flash, and that you can't tell with them.

Alternatively it means that in the almost 100 years of time between the CT era and the TNE era they've learned a few things. Oh, sure the TL's have mostly declined but this could be something they could have done in CT times if they'd known how, but was just figured out recently.