Planetary Masking

[rinku]

As I mentioned in passing earlier, the solar atmosphere or even magnetosphere might be a consideration too. Or at least be an excuse to hand wave it to 100D.
"Can't jump safely with this flux intensity, dammit!"
"Jump with THIS level of Neutrino density? ARE YOU MAD!?"

You can get as detailed as you like with planet density and such or not, but in the end time to jump usually doesn't need to be accounted for that closely. 10 hours to 100D or 7 hours to 100D? Unless you have a ticking clock situation it's really irrelevant, and if you DO need to work it out, go for it.

 

[MasterGwydion]

As I mentioned in passing earlier, the solar atmosphere or even magnetosphere might be a consideration too. Or at least be an excuse to hand wave it to 100D.
"Can't jump safely with this flux intensity, dammit!"
"Jump with THIS level of Neutrino density? ARE YOU MAD!?"

Isn't there already an excuse? Too much gravity. Jumping becomes riskier. Not that you can't do it, but it becomes harder to do safely.

You can get as detailed as you like with planet density and such or not, but in the end time to jump usually doesn't need to be accounted for that closely. 10 hours to 100D or 7 hours to 100D? Unless you have a ticking clock situation it's really irrelevant, and if you DO need to work it out, go for it.

It is important for things such as piracy and customs enforcement. That is kind of the whole reason to have a 100D limit. It creates opportunities for things to happen. Other than that, I agree that it is pretty useless.

 

[Condottiere]

Since jump transitions can't curve, you might arrange to detour around inconvenient gravity wells, to a destination with somewhat profitable trade.

 

[rinku]

Isn't there already an excuse? Too much gravity. Jumping becomes riskier. Not that you can't do it, but it becomes harder to do safely.

It is important for things such as piracy and customs enforcement. That is kind of the whole reason to have a 100D limit. It creates opportunities for things to happen. Other than that, I agree that it is pretty useless.

Yeah, but in practice it's almost always down to:

1. Roll for an encounter or Referee decides to have one happen
2. How long to destination when detected?
3. What range are they when detected?

The one situation where exact numbers might matter is a chase from location to location, especially if the jump point is fairly near.

But yes. The *concept* of a jump limit that must be travelled to before safe jumping is important.

 

[Midas]

I don't know how useful this table will be to anyone, and I don't know where I found this (guessing COTI), but sometime prior to December 2017, somebody calculated all the jump masks for the Spinward Marches. It's canon IMTU.
The forum software doesn't like my table extension, so here's a down and dirty text file copy.

 

[Longboat]

Isn't there already an excuse? Too much gravity. Jumping becomes riskier. Not that you can't do it, but it becomes harder to do safely.

Before I got DGP's SOM, I used to reason that massive bodies have a reflection in Jump Space (as we've been told in multiple sources), and Jumps worked like this:

1. A ship would use its fuel to fire a pattern of energy on the hull grid. The patter set the ship up in J-Space, but this was like taking a wood toy sailboat and launching it down a stream. Once in the stream, the ship would go where the stream took it.

The hull grid is kinda like the act of picking the place where the ship is laid in the stream. Jump Space is the stream, and those within the ship had no control over exiting the ship until it approached its destination.

2. Navigation would point the ship towards a massive body. Usually, that's the destination world or moon. As the ship approaches in the J-Space "stream", the ship hits the 100 diameter of the destination world, and that gravity bubble pushes the ship out of J-Space back into Normal Space.

If you can imagine a large balloon that crosses the stream, our wooden boat softly hits that, allowing the boat to go no father, and the current pushes the toy boat to one side or the other to the shore of the stream. When the toy boat is shoved up on the shore, its akin to the ship in J-Space being forced back into normal space (the ship was precipitated back into normal space, using the term from the old SOM).

3. It's an imprecise calculation, getting the jump grid correct, thus we have the variance in time in jump. You do your best to enter the Jump Stream in a position that will deliver the ship to the Destination Gravity bubble in a weeks time, but that time varies by a few hours. Everything in normal space moves. It's a miracle the Jump Drive works as precisely as it does.

 

[Longboat]

I don't know how useful this table will be to anyone, and I don't know where I found this (guessing COTI), but sometime prior to December 2017, somebody calculated all the jump masks for the Spinward Marches. It's canon IMTU.
The forum software doesn't like my table extension, so here's a down and dirty text file copy.

That can't be for all of the Spinward Marches. There's too few entries. Maybe its for selected worlds. Or maybe a few subsectors?

 

[MasterGwydion]

Before I got DGP's SOM, I used to reason that massive bodies have a reflection in Jump Space (as we've been told in multiple sources), and Jumps worked like this:

Remember, this includes all objects larger than the ship you are flying, including other ships (even a ship can drop another ship out of jumpspace if that ship comes within 100D of the ship). So, does everything have a reflection in jumpspace?

 

[Condottiere]

Causation, etcetera.

The starship hits the wall, or, at least, bounces off a tangible barrier.

 

[Midas]

That can't be for all of the Spinward Marches. There's too few entries. Maybe its for selected worlds. Or maybe a few subsectors?

Hmnn. I notice that the shortest mask is one day six hours. Perhaps the original creator felt that less than a day was immaterial.

 

[WHULorigan]

Remember, this includes all objects larger than the ship you are flying, including other ships (even a ship can drop another ship out of jumpspace if that ship comes within 100D of the ship). So, does everything have a reflection in jumpspace?

Yes, and it is meaningful per the moment of Jump-initiation, for objects at both ends. The larger objects affect the smaller object.

 

[MasterGwydion]

Yes, and it is meaningful per the moment of Jump-initiation, for objects at both ends. The larger objects affect the smaller object.

But a larger object can return you to normal space, say if your path takes you through a star, you are forcibly exited from jumpspace. Easiest way to hit the 100D limit exactly? Calculate your jump to the center of gravity, then you will always exit at exactly 100D. So, it is not only at either end that you have to worry about it.

 

[Condottiere]

You exit anywhere within the confines of a parsec.

As long as you fly like a crow.

 

[rinku]

Given the insanely precise calculations that would be needed to get even within 100D of a world in motion from another world in motion over interstellar distances, I tend towards the jump shadow being a critical part of the process anyway. In system jumps are less problematic, as the error value is orders of magnitude lower.

Charted Space lets you routinely jump from planet to planet, so that's fine and how things are done, but you could easily justify in YTU that you can usually ONLY arrive at the 100D of the target star, but you could jump FROM 100D of anything. Maybe an heroic calculation might let you arrive closer to a planet.

You could think of it like tossing marbles at a large, slowly spinning bowl, with small dents to represent planets outside the star's 100D. You might with supreme skill or luck manage to land in the dent you want to, but mostly it's going to end up at central depression. If one of the other dents gets in the way, you might end up there by mistake.

It's a different dynamic and adds travel time, but has a certain appeal to me.

 

[Condottiere]

 

[Longboat]

You exit anywhere within the confines of a parsec.

As long as you fly like a crow.

I'm not so sure that CT operated that way. My understanding is that, once you're in jump, then you're committed for the full journey. Only a mishap can produce a failure that pushes the ship out of jump space.

Besides, you wouldn't want to exit J-Space early because you'd be in deep space without anyplace to re-fuel. It'd be the last thing you ever do.

 

[MasterGwydion]

You can have a mishap and not fail your roll if there are large mass objects in your trajectory. This could be due to out of date or incorrect navigational information.

Edit - Basically, it would count like a failed roll with a hidden difficulty as the player and character have no way to know that they did anything wrong. They would find out when they exited jumpspace 100D from whatever caused them to exit jumpspace.

 

[WHULorigan]

But a larger object can return you to normal space, say if your path takes you through a star, you are forcibly exited from jumpspace. Easiest way to hit the 100D limit exactly? Calculate your jump to the center of gravity, then you will always exit at exactly 100D. So, it is not only at either end that you have to worry about it.

CORRECT. I should have said anywhere along the jump line.

 

[rinku]

At a distance of one Parsec, an error of one second of arc (1/360th of a degree) puts you off course by 1 AU. By definition.

100D of a size 8 planet is 1.28 million km, or roughly 1/100th of an AU. So you need precision of an order two magnitudes better than that. It's a tough ask - your protractor won't cut it

And yeah. An intervening mass would drop you out early. That can be part of a failed roll - neglecting to account for a body in the origin or target system properly (unknown bodies between the systems are possible, but much, much less likely).

An interesting adventure seed, especially in partially explored systems, might be hitting a large undetected outer system body, even a dim companion, making them arrive... in the system they were trying to leave.

 

[CordwainerFish]

My understanding is that, once you're in jump, then you're committed for the full journey. Only a mishap can produce a failure that pushes the ship out of jump space.

Hm, in my interpretation of jump, any mishap results in part or all of the ship being directly exposed to the ineffable, inimical, and downright eldritch physics of jumpspace, never to be seen again.