Bryn the 2300AD guy
Banded Mongoose
The system seems to assume density increases with size:
Gravity on planets
- Thread starter JNJ
- Start date
Bryn the 2300AD guy
Banded Mongoose
If I adjust the G values to straighten the density curve:
| Size | Diameter | G |
1 | 1600 | 0.07 |
2 | 3200 | 0.15 |
3 | 4800 | 0.25 |
4 | 6400 | 0.35 |
5 | 8000 | 0.5 |
6 | 9600 | 0.65 |
7 | 11200 | 0.8 |
8 | 12800 | 1 |
9 | 14400 | 1.2 |
10 | 16000 | 1.4 |
Bill Sheil
Banded Mongoose
I would stick with the "assume earth density" (=1) statement and correct all of the values to make it consistent with its own text and other Traveller versions by default.
Different densities can be catered for but, as you say, they have an effect ongravity atmosphere as well as things such as mineral potential.
Different densities can be catered for but, as you say, they have an effect on
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Bill Sheil
Banded Mongoose
T5 gives gravities for sample densities IIRC but, at the end of the day, you need a baseline or a formula if you are to extrapolate standard gravities from size and density. So it is not good enough to "assume" that the density changes.
I do not know where these numbers have come from but I will take a look through Traveller versions tonight. It could be that known planetary data was being used (and assumed to be consistent) instead of a formula and the density differences were ignored. The value for a size 4 planet is consistent with Mars (which has a low density).
I do not know where these numbers have come from but I will take a look through Traveller versions tonight. It could be that known planetary data was being used (and assumed to be consistent) instead of a formula and the density differences were ignored. The value for a size 4 planet is consistent with Mars (which has a low density).
Random rolls are not going to model reality. They exist to give the referee a baseline and source of inspiration to massage them into something full of sci fi adventure. The level of realism that entails is the responsibility of the ref based on the degree it matters to their table.
As far as publishing stuff that doesn't match their ruleset, I don't see how that is possible. The ruleset is a guideline for making a subsector. Not the limit of what is possible.
As far as publishing stuff that doesn't match their ruleset, I don't see how that is possible. The ruleset is a guideline for making a subsector. Not the limit of what is possible.
Geir
Emperor Mongoose
WBH keeps the DM+2 for balkanisation. In fact it keeps all the DMs from the Core book. Yes, the Gov 7 DM+2 strikes me as odd also, but it's been consistent through MgT 1 and 2. The other deviation from T5 is that Mongoose Traveller also has a DM-2 for Gov E. No, not arguing that +2 and -2 even out, but just pointing out another deviation. I don't want to speak for Joshua, but I believe TravellerMap doesn't flag the DM variance between versions as out of bounds. And not everything canon even follows anyone's rules; if you look at canon stuff, Efate should fail a test for valid Gov.
I have been assuming that if there had been a major Inner Circle or T5SS issue with the Gov 7 DM, it would have been brought up, but I've only been on the T5SS list for the last 3 years.
One thing in favour of the DM is an assumption of competition and variance between a world's governments. But if so, then the listed TL should really be the max for the world - so it shouldn't be an excuse for throwing a TL12 Grand Duchy on TL7 balkanised world. Just saying...
Geir
Emperor Mongoose
The WBH should be 'real soon now', so you can all throw rocks at me in short order.
On gravity, I didn't see any T5 info. For WBH I reverted to something based on the original WBH where compositional density bands are determined (mostly metal, mostly ice, things like that) and then a second roll gets down to a multiplier of a 'standard' Earth density - where 1.0 is 5.5134 g/cm3.
In a "clean slate" system, I'd go with mass and density first, but with Traveller we start with Size, then go with determining density to back into mass and gravity computations. I stick with the MOARN (Map Only As Really Necessary) principle so it has to start with Traveller UWPs, so they can be left as the only information, if that's what's really needed. But if you want to go into tons of detail, then it is accommodated. Possibly way over-accommodated, but the point of MOARN is that you only have to do as much as you want to.
On gravity, I didn't see any T5 info. For WBH I reverted to something based on the original WBH where compositional density bands are determined (mostly metal, mostly ice, things like that) and then a second roll gets down to a multiplier of a 'standard' Earth density - where 1.0 is 5.5134 g/cm3.
In a "clean slate" system, I'd go with mass and density first, but with Traveller we start with Size, then go with determining density to back into mass and gravity computations. I stick with the MOARN (Map Only As Really Necessary) principle so it has to start with Traveller UWPs, so they can be left as the only information, if that's what's really needed. But if you want to go into tons of detail, then it is accommodated. Possibly way over-accommodated, but the point of MOARN is that you only have to do as much as you want to.
Bill Sheil
Banded Mongoose
No, you are thinking only of simulation here but emulation is also (by definition) modelling reality and can certainly incorporate constrained randomisation (as can stochastic simulations). In fact Traveller's basic universe generation system has always been emulative, not simulative. [From someone who has made a past career in complex system emulation and simulation]. Simulation is worthless for most of Traveller's purposes because unless a simulation model is "mostly complete" (and system evolution models are still highly theoretical) then you are not "modelling reality". You are just testing the simulation model itself.
Mongoose is now publishing its sector guides directly from the TravellerMap/T5SS database. And those sources use a world generation system that differs from Mongoose's own rule systems. But you are correct that it does not really matter so long as the results are described. It just seems pointless to have a varying system in the Mongoose rulebook, one that I suspect is almost never used in preference to the data generated using the Miller Traveller rule systems in TravellerMap and in all of the current and historical source material including Mongoose's own publications.
Efate is certainly an outlier (and always has been) but I think I read somewhere that T5SS was going to impose system bounds on worlds. The closest thing I can see in the TravellerMap Credits is:
.. that might be where I got the notion from. And things like Aramis/Aramis which has now been changed from UWP A6B0556-B to A5A0556-B for no reason (and contrary to the wiki info) but can be half explained if the size was mis-scanned/mis-entered (6->5) and this caused an automatic correction in the legal atmosphere value.
I seem to recollect that T5 gives sample gravities separately for low and high density worlds.
Or, is it possible that no-one has ever noticed
It doesn't matter which way you calculate them, one you have determined two then the third one can be derived and you need all three to determine the surface gravity and orbital characteristics of the world. But where surface gravity is a fairly simple (size * density) calculation relative to a baseline you still need to know the density component. And the statement in the Core Rulebook that the gravity values given are based on worlds with the same density as terra is erroneous regardless of how it is justified for the gravity values given
Geir
Emperor Mongoose
Only on the (decanonized) 1248 map is Aramis still 6B0. And now even the Wiki is 5A0 - except if you read the written description from the GURP data or a note on the discussion tab... I have no idea why that 6B0 -> 5A0 retcon was done. 6B0 is still valid using the 'hot' rules in the Core book, and without them, neither 5A0 or 6B0 would be valid. And neither one changes a trade code. The change that torques me, and I've probably mentioned it before, is Dallia/District 268, whose atmosphere changed from B to 8, suddenly becoming a Rich world, all because someone had bad vision or used bad OCR at some point.
I'm not able to find it in T5.10 Book 3, but to be fair, finding anything in T5 can be... challenging...
(edit: found it: World Map samples)
Or like me, noticed but didn't bring it up. I had a long string on T5SS about the 'Acceptance' cultural trait, which apparently resulted in, um acceptance that Acceptance could be variable, but I haven't seen that reflected in anything published. Maybe T5.11 ?Or, is it possible that no-one has ever noticed
Agreed. Just saying that if I were designing a generation system from scratch I would have started with mass, then determine density to get radius and gravity. With WBH because we start with Size (radius, well diameter, but same difference in relative Earth units), we determine density to get mass and gravity. Either way, add density to determine the unknowns. Ironically for exoplanets, the known quantities are, at best, size and mass, and so density (and once again gravity) becomes the derived value.
Yes. It doesn't even match the examples that well. (For size 3, Mercury - and a Terra-analog, would be about 0.38, and in reality Ganymede has lower gravity than Luna). Maybe next Core version the Surface Gravity column would stay the same, but the sentence would end in 'a density typical of its Size'.
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Arkathan
Emperor Mongoose
Why would the Vilani define 1g as anything other than 1.15g?
Bill Sheil
Banded Mongoose
Dallia was one of the ones I noticed as well I think. The source seems likely to be in optical scanning as B->8 feels like an obvious OCR error. But I had previously been under the impression that the Marches data was already digital and therefore OCR transcription would not have been needed. But I am thinking that Aramis size was also mis-scanned/mis-read
6->5 (also easily an OCR error) and the atmosphere was then autocorrected to A as B would not then have been legitimate. A general problem with these changes is that they lead to inconsistencies in published material and the wiki. Aramis features heavily in the Traveller Adventure Campaign for CT and MgT1 where it is described as having a "swirling corrosive atmosphere".And there is no obvious reason for these changes to have been made deliberately.
Similarly Falcon in the Trojan Reaches went A158448-D -> A558448-D which could have been a mis-scan but the original stats (in Digest 20 and MT Journal 3) were actually illegal in CT so it could have been a legitimate correction, in this case. But the wiki tied itself in knots describing it as alternately a small world and a hollowed -out asteroid before settling on both. And MgT2 PoD still calls it a hollowed-out asteroid while also quoting the world-form UWP.
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I guess I just don't assume that everyone playing Traveller is playing in the Third Imperium setting. Or that if they do, they only play in a published area rather than, say, Foreven or other uncharted areas.
Bryn the 2300AD guy
Banded Mongoose
From the game perspective, having world size and density is useful, since the number of burns in MgT to lift off from a world would be the world size * density.
In 2300AD we have a horribly broken world, King. According to the GDW 2300AD world creation system (and physical reality), it is a gas giant. The best fix is simply to make it a normal heavy-gravity world, i.e. a size-10 world in Traveller (or a dense size-8 world).
In 2300AD we have a horribly broken world, King. According to the GDW 2300AD world creation system (and physical reality), it is a gas giant. The best fix is simply to make it a normal heavy-gravity world, i.e. a size-10 world in Traveller (or a dense size-8 world).
Bill Sheil
Banded Mongoose
I suspect it is a small minority of games, but I still stand by my point that the source data that Mongoose does publish (derived from T5SS) is inconsistent with their own design system.
Well, you can suspect all you want. It may be that most of the non Third Imperium games use Cepheus. Or it may not. But the design of the rules is not intended to be specific to the Third Imperium. Not in Mongoose, not in Classic Traveller. The fact that they publish stuff approved by the T5SS doesn't oblige them to have exactly identical rules for if you were creating our own stuff. And its not like these small differences create significant disparities or otherwise causing problems.
Geir
Emperor Mongoose
For any referee, Rule Zero still applies (which I paraphrase as "Yeah, that's dumb. We're not doing that.") Writers for this rule system are bound more by the rules (or we invent an new rule, which contributes to the rule sprawl problem), but a Referee and a group of players can always go off in a different direction. As for the 3I setting, it is the result of 40+ years under at least half a dozen rule systems across multiple gaming companies and by influence after the fact from 'corrections' some good, some bad, some just plain errors.
You'll find, if you do an analysis for the Spinward Marches, an abnormally large number of Size 5 worlds and a deficient of world sizes 1-4. My understanding is that Don McKinney went through and bumped up the sizes of a lot of the worlds (like where you had a 15XYYYY, you now have a 55XYYYY) to match newer rules and his feelings on what atmosphere a small world could support - theory with that being, I assume, that to maintain the character of the world it was more important to retain the atmosphere than the size. Same with a surfeit of late M class stars, because the habitable zone would be inside of Orbit 0 (yeah, the new WHB will deal with that, hopefully with at least marginal success and correspondence to reality - the TRAPPIST system paradigm could be generated, either by chance or by intention).
You'll find, if you do an analysis for the Spinward Marches, an abnormally large number of Size 5 worlds and a deficient of world sizes 1-4. My understanding is that Don McKinney went through and bumped up the sizes of a lot of the worlds (like where you had a 15XYYYY, you now have a 55XYYYY) to match newer rules and his feelings on what atmosphere a small world could support - theory with that being, I assume, that to maintain the character of the world it was more important to retain the atmosphere than the size. Same with a surfeit of late M class stars, because the habitable zone would be inside of Orbit 0 (yeah, the new WHB will deal with that, hopefully with at least marginal success and correspondence to reality - the TRAPPIST system paradigm could be generated, either by chance or by intention).
Yeah. My point is just that the subsector and system generation systems aren't 3I specific rules. Anyone playing in the 3I setting, whatever percentage of the player base that is, is getting their data from Travellermap, not rolling it up. So the fact that rolling it up wouldn't exactly duplicate the 3I setting because the modifiers aren't exactly the same is not a big deal. That's obviously not what it is for.
Bill Sheil
Banded Mongoose
Which accounts for the changes in Falcon. In this case, though I believe, the size zero -> zero atmosphere/hydrosphere has been in the rules since the first iteration (c. 1977); so it is not a matter of evolution but, probably, an error in the original generation either manually by the authors or software. Obviously size 2 or 3 can retain atmosphere in the Traveller rules but may imply high density for thicker atmospheres
Bryn the 2300AD guy
Banded Mongoose
A size 3 planet needs a density >1.4 of Earth to retain oxygen, and higher to retain N2, in the life zone.
Now, if the planet is further out than the life zone, it is colder, and will retain lower MW gases. The flip side is that it is cold.
Now, if the planet is further out than the life zone, it is colder, and will retain lower MW gases. The flip side is that it is cold.
