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Changing Vector in Jump Space

Here's something new. Has this been discussed yet? According to T5, page 372, a ship can change its vector while in Jump Space.

I'm no expert on this, but up to this point, hasn't Traveller canon been that a ship exits J-Space on the same course, at the same speed that it entered J-Space?

Now, it seems that's the default, but the ship's vector can be altered.

It's interesting. I'm not opposed to the change, though it does raise my eyebrow.
 
Is that 'Jump Vector' as in changing the destination hex? Or real-world vector for after breaking out of Jump Space?

No, just changing speed and direction upon exiting J-Space.

From what I read in T5, there's nothing to be done when the ship exits J-Space. You'll know about an hour ahead of time because of the change in the J-Drive (power use, etc). Then, the ship just naturally translates back into normal space--no one on the bridge needed.

It's like a foreign body being pushed out by the whole.
 
Here's something new. Has this been discussed yet? According to T5, page 372, a ship can change its vector while in Jump Space.

I'm no expert on this, but up to this point, hasn't Traveller canon been that a ship exits J-Space on the same course, at the same speed that it entered J-Space?

Now, it seems that's the default, but the ship's vector can be altered.

It's interesting. I'm not opposed to the change, though it does raise my eyebrow.


I think what is being addressed is a conservation of momentum issue. All other things being equal, a ship leaves jumpspace with the same momentum vector it had when it entered.

But the question that arises is: "What if a ship uses its Maneuver Drive while in Jumpspace?" Suppose it is a Fusion Rocket. Real exhaust reaction-mass is leaving the ship, and hence the momentum vector of the ship is necessarily changed if momentum is conserved (Note that the reaction-mass exhaust will pass beyond the jump field and "disappear" to wherever the Physics of Jumpspace sends it). What happens when you exit Jump? The change in momentum vector needs to be accounted for.

(Note that Maneuver Drives that rely on external gravitational fields to react against, such as G-Drive & M-Drives, will not be able to make such a momentum change, as they have nothing to react against in order to produce acceleration).
 
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Page 372 of BBB : A ship can change its speed and direction while in jump space. Vector change requires non-gravity-based drives or devices; gravity-based drives (due to their need to interact with gravity sources) are generally ineffective.

The top of page 363 lists the types of maneuver drives, and which are gravity-based... pretty much any Mdrive you put on a ship is gravity-based and therefore you can't change your vector. The non-gravity-based ones are not in the core rules.
 
...This is an interesting new 'feature' ... think of the applications;

1) I'm a smuggler or other illicit ship .... law enforcement may know where I am heading (maybe someone ratted us out) and they know my Vector & Delta V as I enter J-space .... but then I deploy my 'secret' reactive thruster while in J-space and when I precipitate out the other end I have a completely new Vector & Delta V :-)

2) Same goes for Military or other ships with sensitive missions ... adds another counter intelligence tool against hostiles/interested parties ....
 
The only problem I see with any of it is... you really don't know where in the new system you are going emerge from J space. Only thing you can be certain of is that you'll be 100D out from the largest body on your Jump-Line. Say you are wanting to emerge out from the mainworld, but vectoring away from it. (for some reason that I don't know of :) ) So in JSpace you change your vector to be 180 degrees from from your line, and accelerate up to 6Gs. But due to a slight astrogation error, you catch one of the outer planets ... a LGG... which now places you in the outer system ... heading further out at 6G... not completely life threatning... but certainly a pain in the thrusters. Or even more fun, you've accelerated up in Jspace and emerge near an asteroid belt... heading directly into it, and going too fast... I guess you could relive the asteroid belt scene from Star Wars. "Never tell me the odds!"
 
Say what?

The only problem I see with any of it is... you really don't know where in the new system you are going emerge from J space. Only thing you can be certain of is that you'll be 100D out from the largest body on your Jump-Line. Say you are wanting to emerge out from the mainworld, but vectoring away from it. (for some reason that I don't know of :) ) So in JSpace you change your vector to be 180 degrees from from your line, and accelerate up to 6Gs. But due to a slight astrogation error, you catch one of the outer planets ... a LGG... which now places you in the outer system ... heading further out at 6G... not completely life threatning... but certainly a pain in the thrusters. Or even more fun, you've accelerated up in Jspace and emerge near an asteroid belt... heading directly into it, and going too fast... I guess you could relive the asteroid belt scene from Star Wars. "Never tell me the odds!"
Not sure where you got the idea (which I bolded) that you don't know where you will be coming out, you should unless you failed your Astrogation roll. What you do not know is how long the Jump will take, but you do know where you're supposed to exit Jumpspace.
 
Not sure where you got the idea (which I bolded) that you don't know where you will be coming out, you should unless you failed your Astrogation roll. What you do not know is how long the Jump will take, but you do know where you're supposed to exit Jumpspace.
True. However, because you don't know when you will arrive, you can't know where the world you're aiming for is going to be relative to where the well-known position you will emerge at is. The world moves and will be somewhere along the bit of its orbit it traverses in 34 hours.


Hans
 
I have the impression that "surprise" exits from J-space happen when the jumping ship passes within 100-diameters of a body with larger displacement than itself. This of course could be another ship but the most likely scienario would be a random encounter with natural minor object in the outer system (Oort Cloud). As has been discussed before; standard procedure would be for ships to adopt a zero acceleration vector (relative stationary) before jump to avoid dropping out of jump space on a collision course with an asteroid. Although it would seem more likely to me that a ship adopt a decelleration profile (tail first) and employee software that puts the brakes on if the ship unexpectedly leaves jump space.

Good astrogation, mapping of system objects, and computing power can all combine to reduce the chances of encountering such an object. Yet, given that they probably exist in the trillions in our own system the complete elimination of such encounters is all but impossible. Given the volume of "space" involved, natural objects forcing ships from jump would be rare under the worst conditions. Contrary to common thought asteroids in the main asteriod belt (far denser than the Oort cloud) are an average of 1.2 million Km apart and so would not look like the floating rock field popularly depicted.

Starting with a minimal chance of a random "dump from jump" modified upward by the depth of a minor object field, and modified downward by the tech of the astrogation and computer, and by the level of the local starport.
 
rancke wrote;

...However, because you don't know when you will arrive, you can't know where the world you're aiming for ....

Time in jump (which is random) is not a factor as Jump occlusion (or 'blockage') is determined at the moment the jump is initiated ....

From page 374 'Blockage'
"The existence of a gravity source (larger than the ship in
jump) on the ship’s course (at any point along the course, at
the moment jump begins
) forces exit from jump at 100 Diameters
in front of the object. The effect is similar to the wave
function collapse in quantum mechanics."
 
Time in jump (which is random) is not a factor as Jump occlusion (or 'blockage') is determined at the moment the jump is initiated ....
You still don't know where your target world will be when you arrive in the target system. So time in jump is a factor.

From page 374 'Blockage'
"The existence of a gravity source (larger than the ship in
jump) on the ship’s course (at any point along the course, at
the moment jump begins
) forces exit from jump at 100 Diameters
in front of the object. The effect is similar to the wave
function collapse in quantum mechanics."
Sadly, this doesn't actually work. At the moment jump begins the target world will be seven day's movement away from the target point and thus there will not be a gravity source there at that point in time. It's only when the ship arrives 168 +/- 17 hours later that there will be a gravity well to force it out.


Hans
 
Sadly, this doesn't actually work. At the moment jump begins the target world will be seven day's movement away from the target point and thus there will not be a gravity source there at that point in time. It's only when the ship arrives 168 +/- 17 hours later that there will be a gravity well to force it out.

I think part of the idea is that the relationship between Jump Space-time and Normal Space-time has quantum mechanical components, and is therefore non-deterministic to some degree. Jump Space-time and Normal Space-time do not map to one another in a linear fashion in this paradigm. So the space-time position of the target-world (within a given degree of uncertainty) determines the exit point and time at the moment of jump. Likewise any potential unexpected intervening gravity-wells (probabilistically with a degree of uncertainty in space-time position for the object).

(That's how I would hand-waive it, anyway. :) )
 
I've just had a thought.

Perhaps it takes a week to be precipitated from jump space.

You open the rift into jump space and move immediately to your destination, where it takes a week to precipitate from jump space.

If another object is within 100D of your jump line you precipitate at that object, but it still takes a week.
 
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