Invention of Synchronised Jumps

Discuss the Traveller RPG and its many settings
Condottiere
Warlord Mongoose
Posts: 7594
Joined: Mon Sep 23, 2013 8:23 pm

Re: Invention of Synchronised Jumps

Postby Condottiere » Sun Nov 10, 2019 7:02 pm

My feeling is that it's a case of diminishing returns when it comes to below planetary sized celestial objects in terms of their gravitational influence, so less than a hundred diameters, otherwise all you need to stop someone triggering the escape route into the rabbit hole is a continuous stream of missiles or an agile drone.
phavoc
Cosmic Mongoose
Posts: 4846
Joined: Tue Nov 04, 2008 6:13 pm

Re: Invention of Synchronised Jumps

Postby phavoc » Mon Nov 11, 2019 2:02 am

Technically, per the rules, ALL objects exert a gravitational field and can affect jumping. A ship that encounters a gravitational object drops out of jump at 100D from that object. So no, a ship could not collide or precipitate from jump space inside another ship. Also, per the rules, a ship retains it's velocity as it entered jump space. So a ship that had been accelerating for say a day at 1G would have a velocity of X. If it encountered an asteroid the size of Ceres, it should end it's jump at 100D and emerge from jump space on the same vector/speed as it had when it jumped.

The rules as written have a lot of logical holes in them, such as how would a ship arrive 100D from a planet that is in a the inner part of a system with very dense asteroid fields? One might say that 'dense' in space is a relative term. And a ship could plan it's jump above or below the elliptical plane. This, of course, assumes it's departure system and jump point origin is properly aligned and the departure system is also clear of asteroids, moons, planets and gas giants in the correct path. Again, with space being large a ship could attempt to fly above or below the plane of the elliptic to clear known debris and objects. We needn't go into the problem then of how any ship could intercept another that made the effort to accelerate and place itself in the proper position to make it impossible for a ship not already on the proper vector, speed and location to intercept it.

One could argue that with all the vagaries of jump that this is exactly why it's important to have updated charts and why it takes so long to calculate a jump vector. Or I'm sure lots of people just handwave it away and say "...and you arrive 100D from the planet." When you handwave things away the bigger question becomes what should you ignore and what should you enforce. The point in purchasing a gaming system with a set of rules is so that you are paying someone to write things up that fit together correctly and you need not handwave things. Traveller isn't the only gaming system that has some work in that area. I think so long as everyone is in agreement of where the modifications are (and sometimes the why), it's easily dismissed and the pew-pew adventures can continue.
Moppy
Greater Spotted Mongoose
Posts: 1202
Joined: Sun Oct 04, 2015 12:42 pm

Re: Invention of Synchronised Jumps

Postby Moppy » Mon Nov 11, 2019 2:29 am

The asteroid belt in this solar system is not as dense as they are in fiction. The average distance between asteroids exceeds that the distance from the earth to the moon.

Certainly the scout service does a lot of internal re-surveys.

You probably don't catch a ship that doesn't want to be intercepted, except that it will want to go to the gas giant to refuel or the main world to commit malarkey and when it does that, you can intercept it. However as I've noted before, because of the speeds involved, you will probably whizz past each other getting only a single firing pass, unless you fight them at the malarkey location (which you don't want to do) instead of trying to keep them away from it.
Reynard
Cosmic Mongoose
Posts: 3455
Joined: Sat Jun 18, 2011 10:03 pm

Re: Invention of Synchronised Jumps

Postby Reynard » Mon Nov 11, 2019 2:58 am

We're very used to the Traveller universe being two dimensional so we assume everything, including star systems as two dimensional. Everyone enters and leaves on the center of the disc. I prefer to believe there's some leeway up and down at least at the system level which is why ships can pass through intervening systems and not hitting every sun and celestial body's jump shadow. Even the Ort and Kuiper clouds have no effect. I'd suggest ships have some maneuver room above the plane of a system so they don't hit every gravity well possible.
AnotherDilbert
Cosmic Mongoose
Posts: 3966
Joined: Wed Dec 23, 2015 2:49 pm
Location: Sweden

Re: Invention of Synchronised Jumps

Postby AnotherDilbert » Mon Nov 11, 2019 12:58 pm

Reynard wrote: We're very used to the Traveller universe being two dimensional so we assume everything, including star systems as two dimensional.
Star systems may be rather two-dimensional, but there is no reason to assume that different star systems are oriented in the same plane.
Image

An incoming jump line can just as well com from directly "up" as through the plane defined by the planetary orbits (≈ the ecliptic).


A much bigger problem than planets or belts is of course the star. E.g. the Earth is just outside the Sun's 100D limit, and the Sun gravity occludes a large part of the Earth sky, so perhaps 40% of all jump directions are blocked at any time. Which 40% of course shifts with the time of year.

If you look at the animation above, all jump routed within a 3D cone around the Sun are blocked. As the solar system rotates the blocked directions rotate. "Up" and "Down" directions off the ecliptic are of course always free. Something like this:
Image
Last edited by AnotherDilbert on Mon Nov 11, 2019 1:32 pm, edited 1 time in total.
AnotherDilbert
Cosmic Mongoose
Posts: 3966
Joined: Wed Dec 23, 2015 2:49 pm
Location: Sweden

Re: Invention of Synchronised Jumps

Postby AnotherDilbert » Mon Nov 11, 2019 1:22 pm

As a comparison we can look at the blocked cone caused by Jupiter:
Image
(orbits drawn to scale.)

Which is tiny in comparison, but can still block the jump route to some star systems for some times of the year if we are unlucky.
AnotherDilbert
Cosmic Mongoose
Posts: 3966
Joined: Wed Dec 23, 2015 2:49 pm
Location: Sweden

Re: Invention of Synchronised Jumps

Postby AnotherDilbert » Mon Nov 11, 2019 1:40 pm

phavoc wrote: Technically, per the rules, ALL objects exert a gravitational field and can affect jumping. A ship that encounters a gravitational object drops out of jump at 100D from that object.
As far as I can see only larger objects block the jump line:
Blockage. The presence of an object (or the 100 D limit of that object) on a courseline. Blockage occurs if the object is larger than the ship in jump.
Blockage
A planned jumpline may be blocked (at any point along the course, at the moment jump begins) by an intervening gravity source (larger than the ship in jump). The ship exits from jump at 100 diameters from the gravity source.
phavoc
Cosmic Mongoose
Posts: 4846
Joined: Tue Nov 04, 2008 6:13 pm

Re: Invention of Synchronised Jumps

Postby phavoc » Mon Nov 11, 2019 1:46 pm

Moppy wrote:
Mon Nov 11, 2019 2:29 am
The asteroid belt in this solar system is not as dense as they are in fiction. The average distance between asteroids exceeds that the distance from the earth to the moon.

Certainly the scout service does a lot of internal re-surveys.

You probably don't catch a ship that doesn't want to be intercepted, except that it will want to go to the gas giant to refuel or the main world to commit malarkey and when it does that, you can intercept it. However as I've noted before, because of the speeds involved, you will probably whizz past each other getting only a single firing pass, unless you fight them at the malarkey location (which you don't want to do) instead of trying to keep them away from it.
Agreed. We don't have any real data on other systems to know just how thick/thin our asteroid belt is in comparison to other systems. There's also the Oort cloud, which is a shell and not spread along the elliptic, that a ship would have to plot a course through.
Reynard wrote:
Mon Nov 11, 2019 2:58 am
We're very used to the Traveller universe being two dimensional so we assume everything, including star systems as two dimensional. Everyone enters and leaves on the center of the disc. I prefer to believe there's some leeway up and down at least at the system level which is why ships can pass through intervening systems and not hitting every sun and celestial body's jump shadow. Even the Ort and Kuiper clouds have no effect. I'd suggest ships have some maneuver room above the plane of a system so they don't hit every gravity well possible.
Yes, that's why I specifically mentioned above and below the plane of the elliptic. Your destination star system might be 'above' you, or 'below' you making the jump easier. And space IS vast, so there's lots of wiggle room. But, at the same time, there are numerous objects out there that you have to thread the needle if you expect to arrive within the 100D of the planet. If, for example, your arrival destination is on the far side of the sun in the target solar system, that sun is going to put up a huge area you cannot jump through. To make the straight-line jump you may have to spend a day accelerating to a point where your jump calculations put your arrival position somewhat at the 100D limit. Otherwise jumping at 100D in your departure system would put you days away from your target.

All these issues aren't insurmountable. However logically the rules don't really take these sorts of things into account. You jump 100D away and you arrive 100D away. Since that's basically how the game operates the rules could be easily modified so that you fix the logical inconsistency. Your jump field/bubble can only form 100D away from a significant gravitational object (small moons or Imperial battle stations 1,000km in diameter could be the smallest object that could influence your jump as an example of the lower limit). Once you enter jump space your ship will re-appear at it's destination. The closest it can be to arrive to a significant gravitation object is 100D. Which, if you wrote it in that sort of fashion, it would ignore suns and planets and you would pass 'through' them if your course intersected one in a straight-line. A simple rule change makes hand waving of things no longer necessary and the rules now match the game mechanics.
Moppy
Greater Spotted Mongoose
Posts: 1202
Joined: Sun Oct 04, 2015 12:42 pm

Re: Invention of Synchronised Jumps

Postby Moppy » Mon Nov 11, 2019 1:57 pm

Most solar systems chartered space will probably be in a similar plane because the whole thing is rotating because of conservation of angular momentum.

One of the planets in our solar system is tiled off axis, probably due to a collision.
phavoc
Cosmic Mongoose
Posts: 4846
Joined: Tue Nov 04, 2008 6:13 pm

Re: Invention of Synchronised Jumps

Postby phavoc » Mon Nov 11, 2019 2:45 pm

The outer arms are more aligned to the elliptic, but we are talking about a galaxy-sized object here. So "along the plane of the elliptic" still means star systems are light years above/below this.

Here's a map showing star systems within 4 parsecs of Earth - http://www.atlasoftheuniverse.com/12lys.html. If you look at the map you can see the variation.
Moppy
Greater Spotted Mongoose
Posts: 1202
Joined: Sun Oct 04, 2015 12:42 pm

Re: Invention of Synchronised Jumps

Postby Moppy » Mon Nov 11, 2019 4:18 pm

Wow, actual faster than light space ships available to the general public, and still the thick galaxy conspiracy persists?
Condottiere
Warlord Mongoose
Posts: 7594
Joined: Mon Sep 23, 2013 8:23 pm

Re: Invention of Synchronised Jumps

Postby Condottiere » Mon Nov 11, 2019 7:04 pm

Charted space is likely to have designated approach lanes, and exit ramps.

Maybe even lighthouses.

Who is online

Users browsing this forum: No registered users and 25 guests