Adzling’s Guide to Chasing Starships

Accelerating a 100 ton mass to .9 times the speed of light takes a tremendous amount of energy and the momentum would be insane. Given the inaccuracy of jump location relative to the targets orbit, a "Planet Killer" jump capable ship is more likely to miss than to actually hit.

Additionally jumping requires a sophont on board to observe the jump or the jump will fail in some spectacular way.

Accelerating a human at 1G (Maximum sustained acceleration vector) to .9c would take about 2 years, I do not think a jump could actually be calculated that far ahead of time

The starship would have to accelerate for a large part of that time in deep space and have 1.4 years of life support for the sophont observing the jump or risk and automated low berth revival just prior to jump.

There are easier and more predictable ways to do massive damage to a planet and its population.

Besides, terrorism doesn't work if there is no one left to be terrorized.
Higher maneuver drive acceleration is covered by inertial compensators, so a maneuver 6 ship would cut that time significantly. 1.75 months according to the online calculator I found.
 
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Additionally jumping requires a sophont on board to observe the jump or the jump will fail in some spectacular way.
Just want to point out that this is not true. The Mongoose rules do have a penalty for a ship jumping without a sentient on board, but it does not remotely convert to "fail in some spectacular way." The -4 penalty just moves the task check from a very easy 4+ to a pretty standard 8+. (And that's not even addressing the fact that no one knows exactly how this became a rule in Mongoose 2e when it isn't in basically every other edition of Traveller).

Also, it is important to recognize that there are at least 3 different guidelines for jump accuracy in Mongoose 2e, which range from "jumps are normally within a few thousand meters of your plot" to "could be 100s of planetary diameters off".

However, you are definitely correct that there are many easier ways to do catastrophic damage to a population than abusing the space magic drives that work the way they do for ease of gameplay, not as a basis for extrapolation to extreme scenarios.
 
It became a rule because it was introduced by MJD and not removed by the editors.
Along came other authors and thought it was a standard rule.
 
I am aware of that. I prefer not to call out authors personally unless I have some reason to think they are acting maliciously. Which is almost never the case in my experience.

It is Mongoose's responsibility to allow or disallow things. I do not know if they did not know this was a new introduction, didn't see it, or actively approved it.

Anyway, probably should have just made my point by stating this is a MgT2e rule and not a wider Traveller rule and left the why element out of it.
 
I don't have history with systems older than MgT1, but assimilated the conservation of momentum piece. The most explicit places of it in MgT2 I've found so far are:
1) Starship Operator's Manual, p. 89 "The ship emerges at minimum 100-diameters from any large mass but retains the realspace vector it had when it entered the jump. The astrogator's job is to compare the velocity that the destination will have upon arrival relative to what the ship has upon jump, to ensure the ship emerges into the target system with a safe and sane vector."
2) Deepnight Revelation: The Near Side of Yonder has a scenario involving a deep-space intercept at 8% of lightspeed, needing around 160 hours of acceleration before jumping for the intercept, and also another 160 hours of deceleration after jumping back from the intercept.
 
Given the overwhelming norm of ships coming to a 'stop' before jumping, is there room to add a penalty to one (or more) steps of the task chain to initiate the jump when a ship is 'in relative motion'? That could encourage leaving such a 'stunt' to the reckless and desperate.
 
Sure. It just depends on how you want it to work and how difficult you want things to be for the players when they step out of the norms.
 
Oh what's the point of wasting time and fuel?
Plot your jump so you are pointing at the planet and decelerate the whole way in.
 
The fact that it doesn't waste any fuel, because the maneuver drive effectively doesn't use fuel? Leastwise, the powerplant uses the same amount of fuel whether the drive is engaged or not. Obviously, if you are playing New Era, that's a different story.

Whether it saves time or not will depend on a bunch of issues, some astrographic, some bureaucratic.
Certain versions of Traveller suggest that stopping before jump is the norm for civilian shipping. Presumably there's a reason. We don't know what that reason is, though. So it is a matter of GM fiat whether that happens and, if so, why.

His question was whether there was a problem in making it a reckless maneuver mechanically. There isn't.
 
Personally, I think the reason for zero was because the distance travelled over time formula assumes zero velocity at both ends. Having two formulae for calculating time of arrival would have been confusing.
 
Of course, I always thought the universe would be much more interesting and playable if jump took a day but the jump shadow was 1,000D instead of 100D, but what do I know.

Interesting that you mention that.

In the initial drafts for T5, that was how the Hop Drive performed, rated in 10's of parsecs range.
The Skip Drive was 10,000D shadows and about 4-hour Skip-duration for 100's of parsecs rated range. (and there were no FTL-Drives greater than Skip).
 
Quite, but there are drives that work in lower gravity, e.g. T5 has NAFAL drives that work out to 1/8 ly or so.

NAFAL Drives ("N-Drives") are rated N1-N9 and have a radial operational range from as system of 1/8 lightyear. But the acceleration rating of the drive is in 0.1g increments and is also coincidentally about the maximum velocity rating in "c" before acceleration cut-off. So an N9 NAFAL Drive produces 0.9g's of acceleration thrust out to about 1/8 ly, by which point it will have achieved about 0.9c (and is a very high TL drive).
 
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This post I made a while back on another thread as a House-Rule may be relevant here (text reproduced below):


Emerging moving at same vector of the object whose 100D limited cause the emergence solves a lot of problems, because it answers the question: immobile relative to what frame of reference? . . .
Actually, this makes for an interesting bit of potential "physics" for both a solution and game play.
So if you "aim" for the jumpline to intersect/overshoot the 100D limit of an object, you force-precipitate out of jump at the 100D limit and simultaneously transfer your momentum and kinetic energy to the "obstructing" body (i.e. your destination star or world) and come out of jump at rest-relative momentum. Consequence is you get a "rough ride" as being forced out of jump by the g-well is always a wrenching experience and can lead to problems (one of the reasons for jump-sickness and equipment failures, etc).
OTOH, if you "plot" a jump to terminate shy of the limit, you exit much more easily, but you need to account for relative momenta, etc. Perhaps a good pilot/astrogator can do some controlled relative momentum transfer in these circumstances as well, but that should be part of the rolls for successful jump (perhaps the closer to 100D, the more you can transfer reliably, but you run a greater risk of hitting the 100D "wall").
Also makes a misjup and it's reason more interesting.
 
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This post I made a while back on another thread as a House-Rule may be relevant here (text reproduced below):



Actually, this makes for an interesting bit of potential "physics" for both a solution and game play.
So if you "aim" for the jumpline to intersect/overshoot the 100D limit of an object, you force-precipitate out of jump at the 100D limit and simultaneously transfer your momentum and kinetic energy to the "obstructing" body (i.e. your destination star or world) and come out of jump at rest-relative momentum. Consequence is you get a "rough ride" as being forced out of jump by the g-well is always a wrenching experience and can lead to problems (one of the reasons for jump-sickness and equipment failures, etc).
OTOH, if you "plot" a jump to terminate shy of the limit, you exit much more easily, but you need to account for relative momenta, etc. Perhaps a good pilot/astrogator can do some controlled relative momentum transfer in these circumstances as well, but that should be part of the rolls for successful jump (perhaps the closer to 100D, the more you can transfer reliably, but you run a greater risk of hitting the 100D "wall").
Also makes a misjup and it's reason more interesting.
Transferring the moment to a planet or even planetoid wouldn't do anything, but this idea raises the very remote possibility of precipitating out of jump 100D from a smaller object, like a ship of space habitat, The instantaneous transfer of a large amount of momentum could really mess things up for people who are just sitting around minding their own business, when suddenly out of nowhere BAM!
 
Transferring the moment to a planet or even planetoid wouldn't do anything, but this idea raises the very remote possibility of precipitating out of jump 100D from a smaller object, like a ship of space habitat, The instantaneous transfer of a large amount of momentum could really mess things up for people who are just sitting around minding their own business, when suddenly out of nowhere BAM!

Correct, it wouldn't solve the high kinetic energy impactor issue, but it would address issues raised upthread concerning reasons why one might choose one way or the other how they wish to emerge from jump (i.e. a standing or running jump): Trying to be at station-keeping and close to the 100D limit (and risk a high momentum transfer and possible transition-related consequences if you are off), or come out of Jump farther out and then have to match momenta and take longer to get to your destination.
 
Correct, it wouldn't solve the high kinetic energy impactor issue, but it would address issues raised upthread concerning reasons why one might choose one way or the other how they wish to emerge from jump (i.e. a standing or running jump): Trying to be at station-keeping and close to the 100D limit (and risk a high momentum transfer and possible transition-related consequences if you are off), or come out of Jump farther out and then have to match momenta and take longer to get to your destination.
To be clear, I wasn't talking about the impactor issue as such, but rather the idea of transferring momentum to the object whose gravity precipitates the starship out of jump. Normally, (accidental) collisions between ships are so unlikely as to not need to be considered, but effectively anyone jumping within 100D of your ship would effectively be transferring all its pre-jump momentum energy to it. (Actually, this could be an impactor problem too, if we consider large ships at relativistic speed). 100D changes the game in terms of probability. Still unlikely, but now you've got this 100D bubble around the ship, making it 1256 times less unlikely.
 
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