So you've misjumped. Now what?
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As I said,
Basically, you get a 33.4-hour window once a week to drop back out of Jump Space. Almost always (normal jumps) you get out in the first window. On a misjump, it may take until the sixth window for the field to collapse. If the jump field collapses outside of those windows, bad things happen (probably) so you need to resume powering the jump drive until the next window. It might not be unreasonable that you could figure out how long the misjump will last (but not its distance or direction) after the first missed window based on what happens when you re-energize the jump field.
Under the 1977 rules, the Jump Drive kicks you into Jump Space and you fall out a week later (or 1-6 weeks later for a misjump) with no extra power to the jump drive.
Under the '81 rules, the Pn=Jn rule suggests that the power plant energizes the Jump Drive for the duration of Jump. This interpretation is supported by starship and non-starship powerplant fuel consumption rates being identical. (That's my take on it anyhow.)
I also want to look at the odds of surviving a misjump (not going "poof" straight off the first die roll, then how likely it is that you'll be able to get to a fuel source to get home), and maybe the financial impact of a months-to-years unscheduled detour on the performance of the ship's mortgage.
Basically, you get a 33.4-hour window once a week to drop back out of Jump Space. Almost always (normal jumps) you get out in the first window. On a misjump, it may take until the sixth window for the field to collapse. If the jump field collapses outside of those windows, bad things happen (probably) so you need to resume powering the jump drive until the next window. It might not be unreasonable that you could figure out how long the misjump will last (but not its distance or direction) after the first missed window based on what happens when you re-energize the jump field.
Under the 1977 rules, the Jump Drive kicks you into Jump Space and you fall out a week later (or 1-6 weeks later for a misjump) with no extra power to the jump drive.
Under the '81 rules, the Pn=Jn rule suggests that the power plant energizes the Jump Drive for the duration of Jump. This interpretation is supported by starship and non-starship powerplant fuel consumption rates being identical. (That's my take on it anyhow.)
I also want to look at the odds of surviving a misjump (not going "poof" straight off the first die roll, then how likely it is that you'll be able to get to a fuel source to get home), and maybe the financial impact of a months-to-years unscheduled detour on the performance of the ship's mortgage.
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When using the Beltstrike fuel consumption table, I was originally inclined to figure a week on the j-drive consumes exactly as much additional fuel as running the m-drive at the equivalent level for a week would. But, see below.
(Bear in mind that asteroid prospecting in Beltstrike involves a lot of free drifting and running endless sensor sweeps, only maneuvering on those rare occasions when there is an interesting reading worth flying over and checking out.)
There are three main variables I can see here: 1) average stellar density within a 36 psc radius, which determines likelihood of popping out in -- or at least close to -- a solar system, 2) the average interstellar density of skimmable brown dwarves in the same area (the existence of which was largely still speculative back in the 1980s -- fortunately current models estimate this number to be fairly high), and 3) The Big One -- how much power plant fuel will be available afterwards to sustain life support during the time needed to detect a fuel source (brown dwarf, Oort cloud comet, TNO-class planetoid, or what have you) and then fly what may be dozens, or even hundreds, of AUs to rendezvous with it.
The idea that the power plant might run out of fuel mid-Misjump -- or even during a normal Jump -- without causing the ship to immediately precipitate out of Jumpspace and back into normal space strongly implies that whatever contribution power plants make to a Jump, it does not actually require a lot of fuel.
My theory is that during Jump, the power plant regulates the energy from the jump capacitors back and forth to the j-drive. For this, the power plant must be operational and capable of functioning at a level least as high as the number of the concurrent Jump, but when supporting a Jump it is powered not by fuel but rather charge flowing in and out of the capacitors, as determined by the Jumpspace topology of the calculated Jump course. It is, in effect a hybrid system of sorts. Should the power plant run out of fuel while in Jumpspace, life support can be switched to the batteries (with non-essential personnel being put into low berths, if available), but the power plant can still hum along, regulating the Jump charge until it all dissipates when the Jump ends.
This is about the only way I can make Misjump work as written without being a TPK by fiat. The upside is that starships barely consume fuel while in Jumpspace, which gives them a fighting chance to come out of even a six-week Misjump with at least half a load of power plant fuel left. Then, as the old saw goes, "Subsequent events are up to the referee."
Enoki
SOC-14 1K
I see it as something more like the 77 rules.
You create a "well" with the drive and are "pulled" into it. This looks like a cone where you come out at the tip of it a week later. It works in part on understanding gravity, that's why you can't be near a large gravity field, only micro-gravity, a "constant" is permissible. Time is supposed to be a constant in this, a week elapsing. Less would destroy the ship, more is unnecessary.
What happens in a mis-jump is the navigation or field generated to open the well isn't performed up to snuff. So it's either the navigator miscalculated where the ship would come out, or the engineer generated the field incorrectly and this made for an improperly formed well.
The bigger the mistake(s), the more error in position you get. When you are way off either the ship gets destroyed or you end up who-knows-where.
If you open the well such that the exit point (where the well collapses to nothing) is too close to a gravity field (eg., a navigation error) it has nasty consequences on the well generated and things like ending up in the middle of a sun or something occurs.
The well is an Nth dimensional thing (more than 3 dimensional) and you are just "falling" through it to the exit point, no need for more power or a field once you enter. You can only exit at the point where the field collapses.
Form it wrong, or put the collapse point in the wrong place and you get bad things happening.
I also make it that the rules version jump requires the ship to be stationary. Jumping while hurtling through space at a gazillion kph (that's a highly technical term) makes for you mis-jumping far more likely. This is because you don't have the precision in navigation to ensure the end point is where it should be relative to your ever changing position. It also means coming to a halt to do the jump--not the best thing when you are being chased by pirates or a government ship bent on your destruction or boarding for whatever...
You create a "well" with the drive and are "pulled" into it. This looks like a cone where you come out at the tip of it a week later. It works in part on understanding gravity, that's why you can't be near a large gravity field, only micro-gravity, a "constant" is permissible. Time is supposed to be a constant in this, a week elapsing. Less would destroy the ship, more is unnecessary.
What happens in a mis-jump is the navigation or field generated to open the well isn't performed up to snuff. So it's either the navigator miscalculated where the ship would come out, or the engineer generated the field incorrectly and this made for an improperly formed well.
The bigger the mistake(s), the more error in position you get. When you are way off either the ship gets destroyed or you end up who-knows-where.
If you open the well such that the exit point (where the well collapses to nothing) is too close to a gravity field (eg., a navigation error) it has nasty consequences on the well generated and things like ending up in the middle of a sun or something occurs.
The well is an Nth dimensional thing (more than 3 dimensional) and you are just "falling" through it to the exit point, no need for more power or a field once you enter. You can only exit at the point where the field collapses.
Form it wrong, or put the collapse point in the wrong place and you get bad things happening.
I also make it that the rules version jump requires the ship to be stationary. Jumping while hurtling through space at a gazillion kph (that's a highly technical term) makes for you mis-jumping far more likely. This is because you don't have the precision in navigation to ensure the end point is where it should be relative to your ever changing position. It also means coming to a halt to do the jump--not the best thing when you are being chased by pirates or a government ship bent on your destruction or boarding for whatever...
One of the interesting side effects of TNE's misjump changes is that most misjumps wind up just 1d6+4 days in jump instead of 7. At the original target point. At 100 diameters from the world.
Now, if you have a significant misjump... you come out not only on potentially the wrong day, but also 2d6 hundreds of diameters, from the world.
And of course, unrefined fuel or jumps from inside 100 diameters... make that classic misjump... and end in orbit 1d20-1 if there is a system there.
So, when you misjump, more than half the time, you're weeks out on a full-burn course... in an edition where you're lucky to have a day's worth of delta-V on even the longest legged ships.
In other words, if you hit the catastrophic misjump, you'd better have some low berths, and convert all your available hydrochemicals into fuel. At least the power plant sips fuel at a slow rate.... because, with only (typically) 2-10 burn units of 30 G-minutes each, you're looking at months travel, perhaps years, or even decades. So you do one of
Now, if you have a significant misjump... you come out not only on potentially the wrong day, but also 2d6 hundreds of diameters, from the world.
And of course, unrefined fuel or jumps from inside 100 diameters... make that classic misjump... and end in orbit 1d20-1 if there is a system there.
So, when you misjump, more than half the time, you're weeks out on a full-burn course... in an edition where you're lucky to have a day's worth of delta-V on even the longest legged ships.
In other words, if you hit the catastrophic misjump, you'd better have some low berths, and convert all your available hydrochemicals into fuel. At least the power plant sips fuel at a slow rate.... because, with only (typically) 2-10 burn units of 30 G-minutes each, you're looking at months travel, perhaps years, or even decades. So you do one of
- point where the nearest source of fuel is, program the computer to wake the pilot when you get near, and have the pilot use that last burn to do a desperation skimming run...
- Point yourself towards the habitable planet, enter the low berths, and set it to wake on close approach by any ship.
- throw one hell of a party, enter the low berths and hope
- rig for growing, and send a distress signal, and wait
- send a distress call, set for wake on ship approach, and enter low berth, hoping for the best
- Throw one hell of a party and turn off the CO2 scrubber and end it all...
I think they broke misjump survival with the '81 rules and didn't notice.
1977 rules didn't need a powerplant for Jump, and every Jump was the same regardless of distance: 10% of the ship's tonnage in fuel based on capability rather than actual distance. A misjump meant you returned to normal space with a bit more than half your powerplant fuel load left, regardless of duration. (The first half was used to get you to Jump Limit outbound.) This lines up with your interpretation of the concept, and it's quite reasonable.
As I see it, it was probably expected to be modified by referee fiat after the roll for misjump, though it wasn't literally written that way. "Ship destroyed" was the mandatory TPK result, and it was up to the ref to decide whether a misjump would be a TPK or not after that. Keep in mind that in the small-universe setting of the first three books the referee might only have generated a couple of subsectors, and a misjump could easily put the players' ship well off the map.
Which meant rolling up a new subsector for them to land in, and then up to three more(!) for the route back home. Want them to survive? Put a world where they misjump to, or bump them a hex or two off the straight-line course to a world that's already on the new map. Want a TPK 'cause they made one too many dumb choices that session and it's just not worth the repetitive stress injury you'll get from all the world-generation rolls? It's an empty hex; time to break out LBB1, blank character sheets, and the dice.
The "Jump needs a powerplant too" rule broke that, because needing a powerplant and its four weeks of fuel for the Jump Drive (not just the Maneuver Drive as in the 1977 rules) meant that the 30-day clock on the fuel endurance started when the ship took off, and kept running through the Jump too. Now a misjump didn't mean always exiting with half the powerplant fuel allocation left, it meant two chances out of six that the misjump would last longer than the powerplant fuel.
The Pn=Jn rule feels like it was brought in from LBB5. Starships without powerplants seem out of place once you start tracking weapon and computer (ECM transmitter) power usage, even if you're not using energy points in the LBB2 design rules. Keeping with the spirit of LBB2:'77, maybe it should have been "Pn=manuever Gs, but never less than Pn=1". Either way, it probably didn't occur to them to consider how it affected misjumps.
The later discoveries of interstellar bodies and the implications of extensive Oort clouds didn't change anything, but they should have.
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LBB2 misjumps that are only from using dirty fuel never yield "ship destroyed" results.
Those only come from jumping from inside 100D. Inside 100D but outside 10D, it's a 2D roll of 8+ (41.67%) to misjump, 11+ (8.33%) to be destroyed, DM+1 if using unrefined fuel (becoming 58.333% and 16.67% respectively).
Jumping from inside 10D is an automatic "ship destroyed" result regardless of fuel.
Those only come from jumping from inside 100D. Inside 100D but outside 10D, it's a 2D roll of 8+ (41.67%) to misjump, 11+ (8.33%) to be destroyed, DM+1 if using unrefined fuel (becoming 58.333% and 16.67% respectively).
Jumping from inside 10D is an automatic "ship destroyed" result regardless of fuel.
Condottiere
SOC-14 5K
1. Astrogation should provide leeway for bufferzone at destination, within known chartered space.
2. Misjump misaligns space and time significantly and noticeably; essentially, it's an art not science.
3. Larger ships probably would have a spare jump capable lifeboat.
2. Misjump misaligns space and time significantly and noticeably; essentially, it's an art not science.
3. Larger ships probably would have a spare jump capable lifeboat.
This seems possible, even likely. '81 CT and HG2 do appear to inform each other.
And do not forget that the '77 rules only required a computer large enough to run the appropriate Jump program; the model number was irrelevant. The need in '81 to match computer model to j-drive smells like a kludge simply to make the ship's HG2 USP more elegant. ("What do you mean I cannot have both spinal mount and bay-mount PAWs in the same ship? Why in the galaxy not?" and so on...)
As to where the vessel comes out of Misjump, obsessively-procedurally-generated Traveller can indeed throw a starship into an entire other, not-prepped-by-the-ref sector -- but somehow that just never seems to happen on those rare occasions when I am running the game and making that particular die roll in secret...
No reason to full burn.
The generic 200dt M1/J1 Free Trader from TNE has 56 G-Turns of fuel, after Jump. A G-Turn is 1G for 30m, so it's 28 G hours of fuel. It also has a 1G drive.
1200 diameters from Earth is "only" (1200 x 12750km) 15.3Mkm.
Half way is 7.65Mkm.
5hrs of 1G (10 G-Turns, 10% of fuel load) is: (simplifying with 1G = 10m/s^2)
v = at, v = 10 * (5 * 3600), v = 180 km/s
d = .5at^2, d = .5 * 10 * (5 * 3600)^2, d = 405K km traveled during acceleration.
Time to half way (7.65Mkm - .405Mkm) at 180km/s, 40250s, 11.18hrs.
So, 16+ hrs to half way, doubled, 32-33 hrs to planetfall.
That uses up less than half of the maneuver fuel in the ship.
I don't think an extra day + in space is (normally) life threatening.
I do suggest you don't misjump to Jupiter.
Proneutron
SOC-13
Not sure about that. A hex is ~18 cubic light years in volume. Even if there are a couple bodies that could provide fuel the odds of being close enough to use the M-drive to reach them are very small. Even a system like ours with an Ort cloud 1 LY in radius only gives ~4 LYs of volume compared to the 18 cubic LYs of space it sits in...
I am aware of assorted House Rules being put forth over the years that have a Misjump always end at the 100D limit of the nearest stellar-sized object to the rolled hex.
This gives a fair chance that a still-living crew can eventually find some source of fuel within sublight flying range.
It may also be problematic regarding supergiant stars, however, so I have always been inclined to give it a pass. It does make some sort of coherent theoretical sense though, Jump physics being as dependant upon the 100D limit as it is. Conceivably, a Misjump could throw a starship well outside the galaxy -- millions of parsecs or more (Cf. Hop, Skip, Kiloparsec, et cetera drives) -- but for a fortuitously-located star within 36 parsecs that anchors the destination end of the errant Jumpspace journey and forces the starship back into normal space, eventually.
This gives a fair chance that a still-living crew can eventually find some source of fuel within sublight flying range.
It may also be problematic regarding supergiant stars, however, so I have always been inclined to give it a pass. It does make some sort of coherent theoretical sense though, Jump physics being as dependant upon the 100D limit as it is. Conceivably, a Misjump could throw a starship well outside the galaxy -- millions of parsecs or more (Cf. Hop, Skip, Kiloparsec, et cetera drives) -- but for a fortuitously-located star within 36 parsecs that anchors the destination end of the errant Jumpspace journey and forces the starship back into normal space, eventually.
Proneutron
SOC-13
Jump physics isn't dependent on the 100D limit. It is simply DANGEROUS to jump within that limit due to gravitational forces. Otherwise, it in no way causes ships in J-space to come towards a stellar object. At least according to all the rules I've read in the various Trav versions.
I can see cutting slack if someone misjumps into a hex with a star system but not just an otherwise empty hex. As most empty hexes probably DO have something like a brown dwarf and it would ameliorate the misjump problem in too large a manner.
I am pretty sure the whole concept of a Jump Shadow means that a vessel cannot emerge from Jumpspace inside the 100D limit of anything material, either deliberately or accidentally. This can have significant military and mercantile consequences, depending on solar system configuration.
I stand by my use of the word.
Proneutron
SOC-13
It is precipitated out when the gravity level is too high. (not in all rules sets though) The gravity well in question has no "pull" on the ship in J-space. It doesn't change its course in jump space. Thus no propensity to draw ships in jump towards it while in jump.
This point has been mooted retroactively in the canon.
More to the issue at hand, in the RAW, Misjump can end in interstellar space. It should be noted that until the Battle of Two Suns became part of the OTU 3I timeline, there was some debate among players as to whether or not a Jump could be deliberately plotted to end deep in the interstellar void, rather than at least in the reasonably-traversable vicinity of a stellar-mass object and its accompanying gravity well.
I suspect that old House Rules about stellar-mass objects naturally forming the endpoint of even plotted Jumps have their origin in this now-resolved ambiguity from the early days of the game; based on conversations about it I had way back in BBS days, part of those referees' rationale was specifically to eliminate the possibility of a Misjump into interstellar space and its associated almost certain doom.
So, you know, they had their reasons.
(For comparison, see also the GT JTAS article by Allan E. Johnson "Across the Galaxy" which is a published Variant interpretation that implies gravity wells are actually what constrain the performance of FTL in Trav. Well, gravity wells and perhaps inadequate mathematics. But this is probably wandering OT here and I include it as background only for completeness.)
It seems pretty clear from everything that the 100D limits pulls you out of Jump space. You can not materialize from Jump within the 100D limit of, well, anything. Moon, Planet, Star, big freighter.
This is from JTAS #24, Marc M's article on Jump space:
What's more in dispute is the whole "pulling out of line-of-jump", but that's remote enough to not really be an issue.
But, as far as coming out of jump, it's not happening within 100D. You show up on the edge.
Misjumps happen when you try to jump OUT within the 100D.
This is from JTAS #24, Marc M's article on Jump space:
What's more in dispute is the whole "pulling out of line-of-jump", but that's remote enough to not really be an issue.
But, as far as coming out of jump, it's not happening within 100D. You show up on the edge.
Misjumps happen when you try to jump OUT within the 100D.
I kind of like the "you have to come out within 100D of something" house-rule as a workaround for deep-space misjump doom. It might just be an ice asteroid out there light-years from nowhere, but it's something you can work with to get out of there. Not really supported by canon, but it's convenient.
The Battle of Two Suns situation seemed a bit awkward. Even if you could do a half-parsec jump to nowhere (which I gather was unresolved at the time it was written), why would you bother except for in-system microjumps? But that touches on something a bit more on-topic: SF writers (and to some extent, readers or RPG players) often have no sense of scale. Worlds are hexes on a map. If you're in the hex, you're at the world; if not, you're in another hex which is either empty or has a world (and you're there instead). That probably worked most of the time, if the ref didn't just quietly nudge the destination over a hex or two (or a subsector or two)...
The TNE misjump rules (you made it to the right system, too bad you're out in the Oort cloud somewhere...) fixed that in their own way.
I really dislike the T5 rule that anything big enough can yank a ship out of Jump -- particularly the "step on the origin point with a battleship" trick. (I've posted elsewhere that this trick can enable very-limited information transfer at up to Jump-21 speed, or just J-7 on the ordinary XBoat network.)
The Battle of Two Suns situation seemed a bit awkward. Even if you could do a half-parsec jump to nowhere (which I gather was unresolved at the time it was written), why would you bother except for in-system microjumps? But that touches on something a bit more on-topic: SF writers (and to some extent, readers or RPG players) often have no sense of scale. Worlds are hexes on a map. If you're in the hex, you're at the world; if not, you're in another hex which is either empty or has a world (and you're there instead). That probably worked most of the time, if the ref didn't just quietly nudge the destination over a hex or two (or a subsector or two)...
The TNE misjump rules (you made it to the right system, too bad you're out in the Oort cloud somewhere...) fixed that in their own way.
I really dislike the T5 rule that anything big enough can yank a ship out of Jump -- particularly the "step on the origin point with a battleship" trick. (I've posted elsewhere that this trick can enable very-limited information transfer at up to Jump-21 speed, or just J-7 on the ordinary XBoat network.)
Bearing in mind that a Jump's destination is fixed at the time it is initiated, I think the idea that a mass "pulls" a ship out of Jumpspace is misleading, and even confusing.
Jump drives are not hyperdrives or warp drives; a trip through Jumpspace is essentially an ideal ballistic curve of sorts: a Jump's endpoints are both fixed from the get-go, hence the need for all the number-crunching by a Big Iron computer mainframe to plot a course for Jumping. As such, the mass at the destination would anchor the precipitation end of the Jump's arc from the moment the Jump is initiated at the origin end.
The conceptual problem has always existed: a starship's position is fixed relative to what, exactly? All reference frames in space are relative to the speed of light, but not to any privileged mass. The idea that starships typically reduce their velocity to "zero" before jumping is nonsensical inasmuch as object's velocity is always velocity relative to something else.
Like, for example the nearest stellar mass a starship is operating in the vicinity of, or (my preferred interpretation) the inertial frame of the entire honkin' galaxy...
For the record, this is why I favor making running Jumps -- they save time, and you can still calculate the route so you arrive at the destination world with (nearly) zero relative velocity.
That's the only way to do it that makes sense from a simulationist perspective. The start/stop at 100D seems to have been arbitrarily imposed to make interceptions easier. Either that, or they didn't even consider the reference frame issue in the first place...
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