Astrogation question

zero said:
So the ship jumps to a pocket universe, then vents the hydrogen? I thought venting the hydrogen was part of the jumping process and the vented hydrogen is the wall to the mini-universe

It is a bit of a chicken and egg scenario.
 
zero said:
So the ship jumps to a pocket universe, then vents the hydrogen? I thought venting the hydrogen was part of the jumping process and the vented hydrogen is the wall to the mini-universe (when all the hydrogen allocated for the jump is vented the ship begins to return to the universe in the parsec allocated.)

To be fair, I havent really properly read the rules for Jumps yet (I've been dealing with system ships before now) so I'll look there also.

Atm I'm going for a combo of DFW and TC's version, the ship gets sucked towards a central pinpoint that swallows it, it then appears at the parsec allocated a week later, as if the pinpoint exited there (if you get what I'm trying to describe, its like when Dr.Weir in Event Horizon describes how the Gravity Drive can go FTL)

Personally I think Mongoose screwed the pooch when it came up with the pumping hydrogen out to make your pocket universe. The old method of charging your jump grid seemed to make more sense, and offered a much better baseline for explaning the jump mechanism itself.

DFW is right in that this is a chicken-and-egg situation now. Mongoose came up with a new version of jumping, but most likely put very little thought into how to justify it somehow. If you are being pursued by the bad guys and you have been accelerating steadily towards the 100D limit, how in the hell are you going to be able to vent hydrogen and actually, I dunno, STAY in the vapor cloud you just created?

Or, if you have to come to a stop without any velocity, that kind of makes you a sitting duck if someone is on your tail. And it certainly signals your intention to anyone chasing you that you are getting ready to enter jumpspace.
 
phavoc said:
If you are being pursued by the bad guys and you have been accelerating steadily towards the 100D limit, how in the hell are you going to be able to vent hydrogen and actually, I dunno, STAY in the vapor cloud you just created?

Just picture it as big and beautiful like a comet. All that venting coming from the bow of the ship, lightning arcing through it (I dunno, just a visual), then poof..... large rad burst or something and then gone.

-V
 
How about a moment of gravitational lensing, as if part of the fabric of space time was being twisted out of existence. A flash of red at its centre, the gravimetric distortion snaps back, and that's it.

Something similar occurs at the moment of entry into normal space. A locus of gravitational lensing forms at the Jump aperture. It builds in intensity: then a blue flash, the lensing snaps back ... and there's a ship at the centre.
 
vitalis6969 said:
then poof..... large rad burst or something and then gone.

-V

Or, hydrogen cloud hit by high intensity laser and poof, fusion. :shock:

Don't think that is really possible though. Good story line?
 
(Not that I like the idea, a fact I have posted on prior occasions, but here is the MgT take...)

Core pg 141 said:
...
To Jump, a ship creates a bubble of hyperspace by means of injecting high-energy exotic particles into an artificial singularity. The singularity is driven out of our universe, creating a tiny parallel universe which is then blown up like a balloon by injecting hydrogen into it. The Jump bubble is folded around the ship, carrying it into the little pocket universe.

My reading of that is that the 'hydrogen bubble' is not in the ship's universe, but in the 'parallel' universe - and starts 'inside' the ship...

As to the last part - 'folded around the ship' - I was picturing more 'engulfed the ship as it expanded'... but, it really is too contradictory to say.

And the re-entry part is really riddled with logical holes, but, hey, its fiction (even if poor fiction) ;)
 
Wow I think my brain imploded when I got to those charts... lol

Returning to the original topic of astrogators... the rules state only that the astrogator has to plot a course, and it jumps (or won't jump if they fail). The astrogation effect has no effect at all on the jump accuracy itself apparently? But the engineer power check does? Surely how good an astrogator's calculations are should affect how close to world X they arrive or if they slam into a gas giant (I'm using Reign of Discordia, where they Tachyon-drive jump through real-space).

I like the idea that a good astrogator will get them closer to their target more accurately, and if they flunk the roll it could cause serious damage to the ship or possibly death.

As a such I'm thinking that if the astrogator gets an effect of 6+ to add a +2 DM to the jump roll, or a -2 DM if they get an effect of -6. In my mind if they fail with a lesser effect then they realise they messed it up and/or the computer's safety prevents jumping. But with a -6 they plot something that they THINK is good, and the computer accepts (because it doesn't know all the variables or the jump point is further than the sensors can detect) but really they've plotted a course close to something bad. Again this is intended with a warp/hyperspace type of drive rather than a jump drive which takes you totally out of the universe.

A second question if I may... it says a ship with a Jump-3 (for example) drive must have the Jump/3 software... does this mean the ship can plot a course (assuming it has intellect and/or agent) as if it had expert/3 (so a Jump-6 would have Expert/6 ?) or must Expert [Astrogation]/2 be bought seperately if the players want to tell the computer to plot a course and jump (or plot a course for the astrogator to verify, and give him/her a +1 DM).

Thanx!
 
FentonGib said:
A second question if I may... it says a ship with a Jump-3 (for example) drive must have the Jump/3 software... does this mean the ship can plot a course (assuming it has intellect and/or agent) as if it had expert/3 (so a Jump-6 would have Expert/6 ?) or must Expert [Astrogation]/2 be bought seperately if the players want to tell the computer to plot a course and jump (or plot a course for the astrogator to verify, and give him/her a +1 DM).

I don't think Jump/N is a navigation program, but rather an automation control program for the jump drive system. The more sophisticated drives take a serious amount of computing power to control correctly, and similarly complex control software.

AFAIK, this part isn't in anyone's rules, but is how I see things IMTU:

I imagine this software generates terabytes of drive control data and then sequences it out to the Jump control system. I imagine that a bis computer has a dedicated data processor that can store and sequence this data with extreme precision, freeing the CPU to modulate the data stream based off of feedback from both internal and external sensors. The bis processor might even be able to handle the internal sensors part of the data modulation. For a J-drive, this processing always adds up to about capacity 5; the rest of the Jump program's capacity requirement involves the external signal processing for the higher dimensions involved, and thus becomes more complex as the jump number increases.

The Jump family of programs (again, IMTU) represent a suite of calculation options, and since each jumpspace "layer" is reached through the lower layers, a Jump/3 package necessarily includes Jump/2 and Jump/1, which it runs in parallel to help generate the complex jumpspace entry sequence. Though all of the Jump programs include the drive/sequencing software, the protocol is modular and can run on the bis processor if one is present. Note that a jump program isn't really a completely separate entity - J2 depends on J1's output, etc..

The Jump drive itself also has that structure - each "jump number" has special hardware to open that layer of space, though there is a lot of shared hardware between the "jump modules", and they aren't really N separate drives.

Anyway, that's the way I like to look at it. Maybe you'll find those ideas amusing as well.

/hdan
 
I don't think there can be a vapour cloud as such, or any external venting of the hydrogen - remember the J-Drive is an internal component; ultimately if there was either a network of vent ports or a 'jump grid' or whatever, then enough external hull damage should wreck it just as it would the sensors, turrets or whatever.

The 'wraps the bubble round' suggests it's opened, then an interface is opened into which the ship can travel - I'd imagine the Farscape starburst is as good a description as any.
 
BP said:
Alternate senarios:
  • Captain: WTF! Computer, lay in a course to use the gas giant as slingshot to get us to 100 D in the quickest time possible.


  • You would never head for a gas giant if you wanted to reach the 100d limit quickly as the 100d limit for a gas giant is far larger that any planets' !

    The astrogator check is really only worth while doing if you are time pressed or trying to do something very accurate like jump into a nebula cloud to hide your system jump entry from potential patrol ships, or jump into the middle of an asteroid belt, in which case you would want to take your time and try to get the calcs spot on. Otherwise its an easy task that you will get right 100% of the time, the only variable will be how accurate you end up at your planned arrival point but in most cases this will not be an issue as space is BIG.
 
I don't mind the hydrogen bubble concept. It makes more sense than big starships burning thousands of tons of hydrogen fusion fuel in a few minutes.

If the hydrogen is vented just before the jump, you don't need to worry about how fast the ship is going, only whether it's accelerating or not while it's venting. If it stops accelerating just as the hydrogen is vented, the hydrogen cloud (as a whole) and the ship will be 'stationary' relative to each other. You'd need to form the bubble very quickly though, because that hydrogen is going to disperse in a small fraction of a second.

Since the ship is moving itself and the spacetime it occupies into another dimension, spacetime in our universe is going to have to close up after it. Distortions in spacetime like that are going to manifest as gravity waves. These will propagate at the speed of light, so there may be a visual distortion, but it will be over so fast there would be no way to observe it without super-sensitive instrumentation.

The process immediately leading up to the formation of the bubble might be visible briefly as an energy discharge into the hydrogen. The spectral emissions of hydrogen are violet, cyan and red in order of increasing intensity. Depending how the ydrogen is excited, emmisisons might be in some, all or a sequence of these colours.
 
hdan said:
I don't think Jump/N is a navigation program, but rather an automation control program for the jump drive system. The more sophisticated drives take a serious amount of computing power to control correctly, and similarly complex control software.

That's how I interpret the rules. You can add Intellect and an astrogation pgm to eliminate the need of a human.
 
nats said:
BP said:
Alternate senarios:
  • Captain: WTF! Computer, lay in a course to use the gas giant as slingshot to get us to 100 D in the quickest time possible.


  • You would never head for a gas giant if you wanted to reach the 100d limit quickly as the 100d limit for a gas giant is far larger that any planets' !

  • You neglected to consider jumping away from the gas giant - not another planet. ;)

    Bear in mind, when jumping, one doesn't have to escape the gravity well of the gas giant to reach the 100D limit - thus the gravity of the planet can be used to advantage.
 
BP said:
Bear in mind, when jumping, one doesn't have to escape the gravity well of the gas giant to reach the 100D limit - thus the gravity of the planet can be used to advantage.

Surely the gravity of any planet, gas giant or no, is going to be pretty minimal (compared to a ship's drive) at anything close to 100D.

If I got my maths right, the gravitational pul of jupiter at 50D is 0.00027 G (anyone up to checking my maths?). Even at 10D it's only 0.0068 G.

Simon Hibbs
 
simonh said:
Surely the gravity of any planet, gas giant or no, is going to be pretty minimal (compared to a ship's drive) at anything close to 100D.

If I got my maths right, the gravitational pul of jupiter at 50D is 0.00027 G (anyone up to checking my maths?). Even at 10D it's only 0.0068 G.

Simon Hibbs

Sounds correct. The surface gravity of Jupiter is only slightly more than 2 Gs...
 
Obviously, if one wouldn't look for a gravity assist unless it was an advantage... ;)

Acceleration is acceleration - a net gain, be it 1% or 20% is still a difference to a gas skimming ship fleeing for the safety of jump space.

Jupiter's equatorial surface gravity is ~2.5Gs (MgT style).
 
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