EVA in Jump Space?

[SpaceBadger]

Reading through ship descriptions in GT: Starships, I noticed the little story in the description of the Liverpool dispersed-hull bulk freighter, in which thieves hid inside a habitat module and shipped themselves as freight, then came out "during the voyage" and stole valuables from other cargo modules. Assuming that "during the voyage" means they came out of their module while in jump space to break into the other modules, this raises a few questions.

If there are answers to these questions in rules somewhere, I'd like to know where; if not, I'd like to hear how you would rule IYTU.

1) Is extra-vehicular activity possible while in jump space?

2) If it is possible to go outside the hull, does it matter whether or not you stay inside the jump grid?

3) If you go outside the jump grid while in jump space, what happens?

4) Does the jump grid on a dispersed structure hull closely follow the outside of each module and connecting struts, or does it form some kind of bubble shape of sufficient size to contain the whole ship?

 

[aramis]

Reading through ship descriptions in GT: Starships, I noticed the little story in the description of the Liverpool dispersed-hull bulk freighter, in which thieves hid inside a habitat module and shipped themselves as freight, then came out "during the voyage" and stole valuables from other cargo modules. Assuming that "during the voyage" means they came out of their module while in jump space to break into the other modules, this raises a few questions.

If there are answers to these questions in rules somewhere, I'd like to know where; if not, I'd like to hear how you would rule IYTU.

1) Is extra-vehicular activity possible while in jump space?

2) If it is possible to go outside the hull, does it matter whether or not you stay inside the jump grid?

3) If you go outside the jump grid while in jump space, what happens?

4) Does the jump grid on a dispersed structure hull closely follow the outside of each module and connecting struts, or does it form some kind of bubble shape of sufficient size to contain the whole ship?

1 - yes. as long as you don't extend more than 1m away from the hull.

2 - the grid is at the hull level, except in certain special cases - stay within a bubble defined by 1m away from the grid.

3 - anything extending past the (highly visible) edge of the bubble loses baryon cohesion, and flies apart into quarks right to the edge of the bubble. The quarks precipitate out separately from the ship. This has been used once as a means to perform a needed amputation without a surgical kit in one game...

4 - closely follows.

My views are strongly informed by DGP's MT-canon Starship Operator's Manual.

 

[Carlobrand]

1 - yes. as long as you don't extend more than 1m away from the hull.

2 - the grid is at the hull level, except in certain special cases - stay within a bubble defined by 1m away from the grid.

3 - anything extending past the (highly visible) edge of the bubble loses baryon cohesion, and flies apart into quarks right to the edge of the bubble. The quarks precipitate out separately from the ship. This has been used once as a means to perform a needed amputation without a surgical kit in one game...

4 - closely follows.

My views are strongly informed by DGP's MT-canon Starship Operator's Manual.

Doesn't Starship Operator's Manual feature a story in which a crewman dies several days after exposure to jump space?

 

[Fovean]

Mongoose Traveller uses a hydrogen jump bubble that surrounds the entire vessel, thus there can be quite a bit of normal space to move around in during jump. I put it at 1 meter from the vessel's longest axis so there are tight spaces and big open ones at the same time.

Personally I've never been a fan of the jump grid because I can't see a way around combat damage not disrupting or damaging the grid thus making jump too risky or even impossible.

 

[Lycanorukke]

Doesn't Starship Operator's Manual feature a story in which a crewman dies several days after exposure to jump space?

IIRC - the medic got sucked out into N-space after a misjump ripped a hole in the hull during transition, the steward went looking inside the compartment but got too close to the jump field protruding into the hole (didn't touch it though), got a bad case of 'jump sickness' and died after a few days because of no medic.

As for can/can't crawl around the hull in jump - just go by Rule Zero: "The GM is always right"

 

[Blue Ghost]

IIRC - the medic got sucked out into N-space after a misjump ripped a hole in the hull during transition, the steward went looking inside the compartment but got too close to the jump field protruding into the hole (didn't touch it though), got a bad case of 'jump sickness' and died after a few days because of no medic.

As for can/can't crawl around the hull in jump - just go by Rule Zero: "The GM is always right"

I think the design rules state a ship uses either a bubble or a grid. The bubble configuation costs nothing and takes up no space in the design, where the grid costs some. Therefore one might argue that as an emergency back up, say a destroyer that's suffered heavy damage but still has its jump drive, it could jump out via a bubble instead of relying on its grid.

Personally, I don't see the advantage in a grid over a bubble.

 

[BlackBat242]

1 - yes. as long as you don't extend more than 1m away from the hull.

2 - the grid is at the hull level, except in certain special cases - stay within a bubble defined by 1m away from the grid.

3 - anything extending past the (highly visible) edge of the bubble loses baryon cohesion, and flies apart into quarks right to the edge of the bubble. The quarks precipitate out separately from the ship. This has been used once as a means to perform a needed amputation without a surgical kit in one game...

4 - closely follows.

My views are strongly informed by DGP's MT-canon Starship Operator's Manual.

So how, on a dispersed freighter with external cargo modules, do the modules make it into jump... seeing as they protrude well over 1m past the ship's structure?

Or do you say that the modules have a jump-grid incorporated into them which hooks into the ship's jump-grid power system?


Just another thing which counts heavily, in my opinion, against having jump-grids.

 

[aramis]

So how, on a dispersed freighter with external cargo modules, do the modules make it into jump... seeing as they protrude well over 1m past the ship's structure?

Or do you say that the modules have a jump-grid incorporated into them which hooks into the ship's jump-grid power system?


Just another thing which counts heavily, in my opinion, against having jump-grids.

The modules typically have a grid. When they don't, a cable-net grid can be bought. Carried ships have a grid, and there is a connection port for using it.

 

[atpollard]

I think the design rules state a ship uses either a bubble or a grid. The bubble configuation costs nothing and takes up no space in the design, where the grid costs some. Therefore one might argue that as an emergency back up, say a destroyer that's suffered heavy damage but still has its jump drive, it could jump out via a bubble instead of relying on its grid.

Personally, I don't see the advantage in a grid over a bubble.

A grid allows a ship to be exactly the same volume in jump space no matter what configuration it is.

A bubble suggests that the volume of the bubble is the critical volume for calculating jump fuel (assuming that the fuel forms the bubble). Assuming a 1 meter thick 'bubble' clinging to the hull, a 100 dT sphere will have a significantly smaller surface area and bubble volume than a 100 dT dispersed stricture - so the sphere should need less bubble (jump drive? jump fuel?) than the dispersed structure.

The grid makes less sense (for the battle damage reasons already mentioned) but the grid matches the jump rules more closely.

 

[samuelvss]

Jump Bubble v. Grids

IMTU, jump bubbles are easier to set up for a standard, self-contained ship, but they lack flexibility. Just as it is more costly and even cumbersome to put tow points and matched tow cables on military vehicles, something that civilian vehicles rarely need, so jump grids bring both a bit of capability and problems.

IMTU, a bubble must be "tuned" to the ship quite exactly, OTW there is both the chance of misjump and a greater use of jump fuel (1D%). The tuning is very important, but fairly straitforward. It can be done in 1D6 at a Class A starport, or hours by a ship with Model/2 or greater. The jump bubble, properly tuned, extends about an average of 1m above the outer edge of the ship and its' components, but has a basically smooth shape, such that on a Sulieman, the sharp angles and top of the turret come within about .5 m, and the space just around the base of the turret is has almost 2m of space between the bubble and the deck. Carried craft can be "tuned in" to the ship's jump bubble, as noted. Battle damage may include hull plates, struts and debris that protrude into or too close to (most Engineering sources use .25m as a guideline) the bubble, creating a chance (+1) or misjump.

A jump grid acts as "instant tuning," and is in effect, "plug and play." There is a jump field created in both cases, which is the same roughly 1m average distance from the hull. This is called a "jump bubble" in common usage, (just as the ignorant refer to carrying "clips" for their autopistols ), causing some confusion in those grounhogs who don't clearly know the difference. A carried craft's jump grid is, by definition, attached to its' carrying ship when they dock. If the ship jumps without it, the jump fuel consumption is reduced proportionately. Modules can be carried as deck cargo if the ship is thus designed, and added and removed between jumps without lengthy tuning that prevents last minute additions. A disabled ship can be attached to one that has the fuel and jump drive sufficient to jump with it, and the connection of the grids (and lashing of the hulls together so there is no relative movement), takes minutes, and the drives of one function to jump the two of them. A small craft can be docked to a ship that does not normally carry it, with a potential reduction in jump number, and change in jump fuel consumption.

A hole in the grid causes minor problems, as the jump field will sag. If it sags enough, then this can cause a clearance problem, from the underlying structure or debris, with a possibility of misjump, as with the bubble discussion, above. Generally, a massive hole will require grid jumpers or even a net. This is an Engineering function, though Mechanical skill is useful in cutting away rubble that is protruding. The jumpers are magnetically attached, and do not require any actual mechanical or electical process to connect. An EVA is always required to attach jumpers, however. A net, however, requires 1D6 turns to employ in EVA, and is usually only carried on military ships, or those with a particular need, such as Belters or those working in salvage.

 

[DaveChase]

IMTU, jump bubbles are easier to set up for a standard, self-contained ship, but they lack flexibility. Just as it is more costly and even cumbersome to put tow points and matched tow cables on military vehicles, something that civilian vehicles rarely need, so jump grids bring both a bit of capability and problems.

IMTU, a bubble must be "tuned" to the ship quite exactly, OTW there is both the chance of misjump and a greater use of jump fuel (1D%). The tuning is very important, but fairly straitforward.
...

I disagree with this part of you post. To me what makes the Jump Bubble in some situations more desire able is that it is adjustable up to the maximum ship tonnage it was original designed for.

I do agree that it must be tuned but any Engineer can do that. It might take longer than a jump grid to get the ship ready for Jumping (one of the benefits for a J grid over a J bubble).

But if you have a modular ship design that changes size and shape or you have to load on external modules that might not have a grid built into them, a J bubble is your best bet.

I think (IMO) that a Jump Bubble should cost less than Jump Grid when you purchase a ship but the maintenance cost should be a bit higher (another benefit for a J grid).

Again these are just my view on the J bubble and J grid. No hard official rules quoted here.

Dave Chase

 

[Icosahedron]

I've seen this discussion in another thread within the last year or so.
IMCTU there are no jump grids, but the Jump Drive creates a zone related to a Black Globe (hence the globe uses jump capacitors to store energy). In Jump Space a ship is contained within a sphere of real space that encloses the ship. This is probably more than a metre beyond its longest dimension, but I haven't needed to specify it exactly. Inside that sphere, EVA is harmless, but beyond it is nothing. No space, no time, no white noise, no monsters, just nothing. Anyone inadvertently straying outside the sphere would find himself in a separate pocket universe with no way back. The 'edge' of the sphere is an event horizon. You don't know when you've reached it, there are no tell-tale glowing lines, but if you're facing the ship you'll notice it fading to black as you move away. The EVA manual says stop before you lose sight of it!

 

[Carlobrand]

The modules typically have a grid. When they don't, a cable-net grid can be bought. ...

So ... were I so diabolically inclined, I could take a standard 50 dT 4g cutter, expand the bridge by another 10dT, add a 4 dT jump-1 drive, Model-1 computer, a 10 dT fuel tank, and a 4 dT stateroom, give it a cable-net grid to fill out to 100 dT volume (I have 1 dT left for storing the grid), and have a jump capable cutter that no one would suspect is jump capable unless they saw me erecting the grid. There's some espionage potential here.

Or I could replace the stateroom with a 2 dT small craft cabin and a couple of emergency low berths to make it a jump-capable lifeboat accepting ten (counting pilot and copilot).

The works could be in a 30dT cutter module.

 

[Fritz_Brown]

No, no, no! No thinking outside the box allowed! Get back in your box, Carlobrand!

 

[SpaceBadger]

I'm not a fan of FaceBook, but for certain forum posts I really wish I had a "Like" button.

Thanks for all the input on jump space, grids, and bubbles.

Anybody wanna talk similar effects of EVA outside ships using stutterwarp in a 2300AD setting? Or should I ask that over in the 2300AD subforum?

 

[Carlobrand]

No, no, no! No thinking outside the box allowed! Get back in your box, Carlobrand!

LOL. :rofl:

You know, I kind of like the cutter-lifeboat idea. Reminds me of the collapsible boats some ocean-going ships used for lifeboats. It's a collapsible jumpship. A misjumped cruiser could use one to fetch help. Even some of the larger destroyers carry two or more cutters; one could be used in that role.

That's what I like about these posts they stimulate my thinking.

 

[samuelvss]

So ... were I so diabolically inclined, I could take a standard 50 dT 4g cutter, expand the bridge by another 10dT, add a 4 dT jump-1 drive, Model-1 computer, a 10 dT fuel tank, and a 4 dT stateroom, give it a cable-net grid to fill out to 100 dT volume (I have 1 dT left for storing the grid), and have a jump capable cutter that no one would suspect is jump capable unless they saw me erecting the grid. There's some espionage potential here.

Or I could replace the stateroom with a 2 dT small craft cabin and a couple of emergency low berths to make it a jump-capable lifeboat accepting ten (counting pilot and copilot).

The works could be in a 30dT cutter module.

IMTU, I have this capable of being done with cutter modules, such that the powerplant and M-drives of the cutter are joined with a "jump" module with drives and more fuel, and 5 other cutter modules for a modular Type-A.

 

[Enoki]

1) Is extra-vehicular activity possible while in jump space?

I say no. The vehicle is essentially in an alternate dimension outside normal space. I see it as you can't even do things like open a hatch and throw the garbage out without letting the alternate dimension in and you ending up in it.

2) If it is possible to go outside the hull, does it matter whether or not you stay inside the jump grid?

Not applicable the way I do things.

3) If you go outside the jump grid while in jump space, what happens?

Essentially you enter the same alternate dimension the ship is in but, since you have a different vector you end up dropping out of it roughly the same time as the ship but not with the ship, sort of like a mini-mis jump. Assuming your oxygen holds out the rest of the crew might try to find you floating in a few billion cubic miles of space near them.

4) Does the jump grid on a dispersed structure hull closely follow the outside of each module and connecting struts, or does it form some kind of bubble shape of sufficient size to contain the whole ship?

Kind of neither but both... I see the jump system as the ship opening a gravity well / wormhole-like structure ahead of the ship. Think of this like dropping a heavy marble on a sheet of thin rubber. The jump drive bends the real space locally into a "well" based on how powerful the drive is. The reason the distance is limited is that you can only bend things so far before they start tearing.
The ship then drops into this well in an alternate dimension sort of like dropping something heavier than water into a swimming pool or lake. The ship falls to the bottom of the well were the well basically collapses and the ship pops back out into normal space at the far end.
The ship moves in a straight line or curve (your choice as to which or possibly allowing both) smoothly from start to finish as there is nothing in the alternate dimension to preturb its trajectory.
Going outside or putting anything through the sealed hull means that outside comes in to the extent it can just like water and if you go outside you become what is essentially a seperate thing from the ship.
Because this is an alternate dimension, things in it do not appear to you in three dimensions. Finding your way back may or may not be possible even tehered to the ship due to disorientation.

So stay in the ship for a week and play gin and be nice to the rest of the crew....

 

[SpaceBadger]

Thanks, Enoki. What you describe sounds to me more like a kind of artificial wormhole than the way I think of Traveller jumpspace w the jump grid holding the ship together and all that. I think if I ever switch to something more like Pournelle's Alderson Drive (precise jump points connected by links, with instant transport point-to-point), then I would probably make it work somewhat like you describe.

 

[Rigel Stardin]

Ambulance Ship By James White has a description of one of the nurses working outside during jump.