Another Empress Wave theory

[TheEngineer]

Hi,

if we use the 100D rule consequently, does anybody has an idea how to calculate these limit e.g. for low density gas giants, there the athmossphere is stretching far out, for a gas cloud or any other object where it is hard to define a borderline and a related diameter ?

That was a common question of quite a few Traveller players I know. And that was the reason why I finally decided to use gravity for jump limit definition....

Ideas ?

Mert

 

[EvilDrGanymede]

Originally posted by TheEngineer:
Hi,

if we use the 100D rule consequently, does anybody has an idea how to calculate these limit e.g. for low density gas giants, there the athmossphere is stretching far out, for a gas cloud or any other object where it is hard to define a borderline and a related diameter ?

All gas giants have radii defined for them - in practise a jovian's radius is set at the level in the atmosphere where the atmospheric pressure is equal to that at Earth's surface (1 atm). So just use that level as the planet's radius, and multiply by 200 to get the 100D distance.

gas clouds and nebulae don't have 100D limits - they're too diffuse. Individual objects within them might have 100D limits though.

 

[TheEngineer]

Hi Dr.

thanks for instant reply...

For things like gas clouds etc. how would you handle jump in/out of these objects ?

Mert

 

[EvilDrGanymede]

Originally posted by TheEngineer:
Hi Dr.

thanks for instant reply...

For things like gas clouds etc. how would you handle jump in/out of these objects ?

Hadn't really thought about it myself... I guess jumping out of a nebula would be problematic - IIRC the canonical way to jump is to emit a 'bubble' of hydrogen around the ship, which is then energised by the jump grid on the hull and that opens the hole into jumpspace. If you have excess hydrogen gas around the ship (as you might in a nebula) then that might deform or extend the bubble, increasing the chances of a mishap or misjump.

I don't think jumping INTO a nebula would be a problem though.

That's just IMO though. I dunno if there's an official answer.

 

[TheEngineer]

Where is this canonical stuff with "hydrogen to form a jump bubble around a ship" from ?

TNE ?

Regards,

Mert

 

[EvilDrGanymede]

Originally posted by TheEngineer:
Where is this canonical stuff with "hydrogen to form a jump bubble around a ship" from ?

Now you mention it, I'm not sure. I've always assumed it's canonical... maybe it's from GURPS Traveller. Or it could be the DGP Starship Operators Manual (and if that's the case, I guess that means it's not canonical after all). I'll ask on JTAS - meanwhile if anyone else knows, feel free to chip in here

.

 

[Andrew Boulton]

I think we're still talking about probabilities vastly less than 1% (unless you really goof the astrogation roll). Space is simply not crowded enough to make that probability any higher.

Either there is a chance of hitting something en route, in which case the rules should reflect this, or there isn't, in which case we should just forget the whole idea.

 

[Andrew Boulton]

Where is this canonical stuff with "hydrogen to form a jump bubble around a ship" from ?

Possibly SOM, or it might never have actually made it into print.

Actually burning that much fuel would vapourise the ship, so the traditional handwave is that most is used as coolant and/or to form the jump bubble.

 

[EvilDrGanymede]

Originally posted by Andrew Boulton:
Either there is a chance of hitting something en route, in which case the rules should reflect this, or there isn't, in which case we should just forget the whole idea.

That's what the jump masking rules are for. In GT at least, one of the rolls you make when you jump is an Astrogation roll to avoid intersecting the 100D limit of any intervening objects.

 

[mike wightman]

As far as I can tell hydrogen forming a jump bubble appears first in the SOM and then in T4's FF&S2, Gurps Traveller and most recently in T20.

 

[far-trader]

Originally posted by Sigg Oddra:
As far as I can tell hydrogen forming a jump bubble appears first in the SOM and then in T4's FF&S2, Gurps Traveller and most recently in T20.

Have to disagree, while SOM does talk about a jump bubble it does not tie in hydrogen to it (iirc and after a quick look). Can't speak for FF&S2 or GURPS though.

 

[kaladorn]

I don't recall seeing that in SOM.

I always thought the hydrogen was somehow rapidly turned into energy which was dumped into short term jump capacitors and then shunted through the zucchai crystals into the lanthanum hull grid. The energization pattern on the lanthanum hull grid served to tear a rent in the fabric of nearby realspace, exposing an entry into jumpspace (conveniently situated in front of the ship or around it) and you entered jumpspace and the rent closed behind you.

 

[EvilDrGanymede]

Actually, I don't think it is canonical - my apologies. There's something in the SOM (page 12-14) about maintaining a bubble of realspace around the ship, and Hans came up with the idea that it's hydrogen.

So never mind - sorry for the confusion .

 

[Andrew Boulton]

In GT at least, one of the rolls you make when you jump is an Astrogation roll to avoid intersecting the 100D limit of any intervening objects.

Pity this doesn't appear anywhere in CT, MT, TNE, T4, and (AFAIK) T20.

It does also require that, in order to safely jump, you need to know the exact position and orbit of every star, planet, asteroid, comet, ship, etc between here and there, which is a clever trick in unchartered areas.

 

[Andrew Boulton]

I always thought the hydrogen was somehow rapidly turned into energy

Even at 99.999% efficiency, the waste heat from fusing that much hydrogen would turn the entire ship into energy, hence the coolant/bubble theory.

 

[EvilDrGanymede]

Originally posted by Andrew Boulton:
It does also require that, in order to safely jump, you need to know the exact position and orbit of every star, planet, asteroid, comet, ship, etc between here and there, which is a clever trick in unchartered areas.

Doesn't CT have 'jump tapes' that you need to have in order to jump to a system? I thought those basically did the same thing as the Astrogation roll. (if so, how do you jump to uncharted systems?).

Anyway, you easily could spot the stars and planets from a nearby system using telescopes and plot out their positions and orbits, extrapolate for lightspeed delay, and so you'd have a pretty good idea where the big bodies with the big 100D limits are. You wouldn't need to worry about asteroids and comets because it's so unlikely that you'd run into them (just like there's a chance that you might hit a deer on the way to work in your car, but you don't factor that into every journey you make! If it happens, it happens.).

 

[kaladorn]

Originally posted by Evil Dr Ganymede:
(just like there's a chance that you might hit a deer on the way to work in your car, but you don't factor that into every journey you make! If it happens, it happens.).

Not to detract from your point, but I dodged two on the road at different points last night. And a racoon. In fact, not factoring deer into your driving around here is likely to lead to an ugly accident. I must dodge about 20 or 30 times in a year.

As to jump tapes, I assume this is the database upon which your astrogation roll is applied. Of course, you might have specific pre-plotted jumps, available as a download, so you wouldn't have to have an astrogator aboard. But these might have predictable arrival points (hello Pirates!) and might also go dangerously stale over time...

 

[EvilDrGanymede]

Originally posted by kaladorn:
Not to detract from your point, but I dodged two on the road at different points last night. And a racoon. In fact, not factoring deer into your driving around here is likely to lead to an ugly accident. I must dodge about 20 or 30 times in a year.

There would be somebody who lives in Deer Central here when I use that analogy, wouldn't there...

I just picked that because around here at least, it's pretty unlikely. Obviously you have the option to change your direction and avoid the deer, but a jumpship IIRC can't change direction in jumpspace.

If it was jumping into a system that had a *lot* of large massive bodies all in direct line of sight between the ship and the destination world (maybe if it was jumping exactly within the system's ecliptic plane?) then it MIGHT be worth worrying about intersecting the 100D limits of those. But most of the time that won't be the case, and even if it is in the ecliptic it's still unlikely that the ship would come across an asteroid.

 

[kaladorn]

Originally posted by Evil Dr Ganymede:
There would be somebody who lives in Deer Central here when I use that analogy, wouldn't there...

Around here, I often wonder if they should issue a hunting license and tags at the same time you renew your *car* license.... and I live within 30 mins of Ottawa.

If it was jumping into a system that had a *lot* of large massive bodies all in direct line of sight between the ship and the destination world (maybe if it was jumping exactly within the system's ecliptic plane?) then it MIGHT be worth worrying about intersecting the 100D limits of those. But most of the time that won't be the case, and even if it is in the ecliptic it's still unlikely that the ship would come across an asteroid.

Oh, quite likely. Given that Marc never has said what the mass threshold is that invokes the effect (if you're using the canon version), we don't really know how massive a body must be before it starts to generate this. Is a Free Trader big enough? Couldn't say. Is a Tigress? How about a Pinnance? I have no idea.

I much prefer the gravity answer, even if it does complicate some things (PS, I prefer the version without tidal forces where some planets do end up inside the stars limit....).

 

[Anthony]

Originally posted by kaladorn:

I much prefer the gravity answer, even if it does complicate some things (PS, I prefer the version without tidal forces where some planets do end up inside the stars limit....).

Some planets still do. Just not for G-class stars.

The reason for the tidal limit is that it's the only formula that can produce numbers resembling the 100D rule.