Author Topic: Interstellar Operations Open Beta Test: Solar System Generation: Discussion  (Read 56186 times)

kato

  • Captain
  • *
  • Posts: 2417
The chance for rings on gas and ice giants should be expressed in a D6 fashion; sure, it's no problem to roll for "4 in 6 chance of rings", but a "planet has rings if player rolls 1D6-2 > 0" sounds "cleaner" within the overall context.
Also, i'd prefer it if there was some sort of further definition for rings - in particular regarding relative orbital position with regard to moons of that planet!


The number of system objects, including moons itself seems to be within a realistic range to me - i rolled a trial M2V system with 12 planets and no less than 107 moons, with 19 of them being significantly sized (Medium or larger). Maybe slightly high, but within a realistic range.

Within that context, the fixed orbital slot distance values (both for planets and moons) do look a bit odd to me though. It would be "nice" to have some variation rule to this laid out - say a +-50% variation depend on a 2D6 roll modified by the planet's gravity or something like this. For moons that do not mesh with the given suggested spacing just look in the sky for the closest one to us.

The same applies to planets - every M2V system (as an example) has its potential planetary seed lumps forming in the accretion disc at the exact same orbits? Sounds rather odd to me. Especially since having a similar variation rule as above would give some limited flexibility to the number of potentially habitable orbital slots (since that's a fixed value now).


One additional thing noticed is the surface water rule. My sole habitable planet within the rolled M2V system has a Life Zone Position Modifier of 0.0672 - meaning no matter what i roll (and unless my escape velocity modifier is huge, which it isn't), i always round to 0 or 1 as the closest integer in such a system. Even given the giant terrestrial bonus that always produces a pretty dry world that doesn't conform with the description of a giant terrestrial planet as given in the document.

Calculating the km distance, using the approximate AU value provided of 150 million km
The AU value used to calculate those AU in the chart is probably approximately 148.7 to 149.0 million km, with some rounding - and it seems to not be constant. It should be 149,597,870,700 m to conform to current IAU standard.
« Last Edit: 04 November 2012, 17:32:45 by kato »

PsihoKekec

  • Captain
  • *
  • Posts: 3089
  • Your spleen, give it to me!
One additional thing noticed is the surface water rule. My sole habitable planet within the rolled M2V system has a Life Zone Position Modifier of 0.0672 - meaning no matter what i roll (and unless my escape velocity modifier is huge, which it isn't), i always round to 0 or 1 as the closest integer in such a system. Even given the giant terrestrial bonus that always produces a pretty dry world that doesn't conform with the description of a giant terrestrial planet as given in the document.

Did you mix Life ZoneWidth with Life Zone Outer Edge? It happened to me and I also got very low result, with the same star type no less.
Shoot first, laugh later.

kato

  • Captain
  • *
  • Posts: 2417
Did you mix Life ZoneWidth with Life Zone Outer Edge?
Hmm, guess so, now that you're pointing it out. Life Zone Position Modifier for M2V should be 0.72916667 then?

---

Separate note: Asteroid belts get insane populations when located farther out. The maximum calculable within the ruleset would be a population modifier of 61450 (i.e. total population of 72,752,535,800 objects including 245,800 dwarf planets of >600 km diameter in a B0V system), but even for a bog standard G4V system with asteroid belt at orbit 8 the number of dwarf terrestrials in it can already exceed 50...

kato

  • Captain
  • *
  • Posts: 2417
Elliptical orbits are discussed under Options...or they're not. Gee, I made the reference in Step 2, Placing Orbits but never got around to including them.
Umm, don't you simply call that option "Eccentric Planetary Orbits" on p. 19?

Ryumyo

  • Warrant Officer
  • *
  • Posts: 466
  • Out site seeing...
Thanks Cray !

specter

  • Private
  • *
  • Posts: 28
Yep.

Any chance, that my response to your challenge has been overlooked and not just ignored?  :(

Acolyte

  • Lieutenant
  • *
  • Posts: 1475
pg. 20 under "Realistic Planetary Placement" - Asteroid Belts: - is not bolded.
Pg. 26 under "Industrial Development" 2nd paragraph down - "production of medium lasers and BattleMech chasses is not indicative...." should be chassis (plural is same as singular)
pg. 31 top of left column 2nd paragraph - Dictatorship: - is not bolded

Would you like these posted to the errata? I think your reply got lost in all the square dancing.  ;)

Hey, some people juggle geese.

Thank You
   - Shane
It is by caffeine alone that I set my mind in motion
It is by the coffee that my thoughts acquire speed
My teeth acquire stains
The stains become a warning
It is by caffeine alone that I set my mind in motion.

cray

  • Freelance Writer
  • Major
  • *
  • Posts: 6266
  • How's it sit? Pretty cunning, don't you think?
Umm, don't you simply call that option "Eccentric Planetary Orbits" on p. 19?

...no, because for some reason I used "eccentric" instead of "elliptical," so my quick search through the document didn't find it.

Incidentally, I will be prone to forget contents of this document because the bulk was drafted well over a year ago.

Any chance, that my response to your challenge has been overlooked and not just ignored?  :(

Oh, I was waiting for you to fill out the second part of the challenge, the impacts on the other parts of the rules. You said you needed some time.

Hmm, guess so, now that you're pointing it out. Life Zone Position Modifier for M2V should be 0.72916667 then?
Separate note: Asteroid belts get insane populations when located farther out. The maximum calculable within the ruleset would be a population modifier of 61450 (i.e. total population of 72,752,535,800 objects including 245,800 dwarf planets of >600 km diameter in a B0V system), but even for a bog standard G4V system with asteroid belt at orbit 8 the number of dwarf terrestrials in it can already exceed 50...

Highly populated asteroid belts seem common and plausible. For example, some models of the Kuiper Belt suggest it started off with a total mass of 30x that of Earth, though it is now estimated to hold 0.1 - 0.04x the mass of Earth.


I created a G0V star.  Easy enough.  Found out that it had 6 orbits.  Cool.  Determined that orbits 3 and 4 were at 1.1 and 1.76 AU, respectively.  Checking the Primary Solar Stats Table, I find that both of those orbits are in the life zone, albeit just barely for orbit 4.  Calculating the km distance, using the approximate AU value provided of 150 million km, I find that orbit 4 is at 264 million km.  Checking the Solar table again, orbit 4 is now outside the life zone.  Using the actual AU distance, I can get orbit 4 inside the life zone.  So that's kinda confusing that you can get can a planet that is inside the life zone (by AU), and outside (by km calculated from the provided approximate AU value).

The Primary Solar Stats Table was produced by another writer with a willingness to use more exact numbers than I. What I'll do is provide an optional exact value for an AU if players don't feel like using the 150 million km approximation.

Quote
Also, on the example on page 6, 'Chuck' calculates the AU distance for the inner and outer life zones.  It is confusing why this is shown, because those AU values are shown in the chart he just reference to get the km values.  In addition, the calculated AU values don't match said chart.

Ick. That's what I get for crunching the numbers with my approximate value rather than using the chart. I'll fix the example.

Would you like these posted to the errata?

Please do, thank you.
Mike Miller, Materials Engineer

**"A man walks down the street in that hat, people know he's not afraid of anything." --Wash, Firefly.
**"Well, the first class name [for pocket WarShips]: 'Ship with delusions of grandeur that is going to evaporate 3.1 seconds after coming into NPPC range' tended to cause morale problems...." --Korzon77
**"Describe the Clans." "Imagine an entire civilization built out of 80’s Ric Flairs, Hulk Hogans, & Macho Man Randy Savages ruling over an entire labor force with Einstein Level Intelligence." --Jake Mikolaitis


Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.

Frabby

  • Major
  • *
  • Posts: 4242
"All the Pretty Colors", left column, 3rd line from below: Tau Ceti (New Earth in BattleTech) - Not every reader might immediately understand this. To clarify, I suggest to write it Tau Ceti (aka "New Earth" in BattleTech) instead. Btw I think New Earth applies only to the planet, and the sun is still technically named Tau Ceti in BattleTech.

Why are Giant Moons uninhabitable by default? Shouldn't their principal planet effectively shift the lifezone for its moons outward instead of eliminating it? Edit: Forget this point. Found it in the Options section.

P. 11, right column, 3rd paragraph: "For the same reason, players should also feel free to declare a planet uninhabitable..." - should presumably read "habitable" instead.

« Last Edit: 05 November 2012, 12:23:51 by Frabby »
Sarna.net BattleTechWiki Admin
Author of the BattleCorps stories Feather vs. Mountain, Rise and Shine, Proprietary, Trial of Faith & scenario Twins

PsihoKekec

  • Captain
  • *
  • Posts: 3089
  • Your spleen, give it to me!
Hmm, guess so, now that you're pointing it out. Life Zone Position Modifier for M2V should be 0.72916667 then?

Let me check my notes...yes that's the result I got as well.
Shoot first, laugh later.

Talz

  • Sergeant
  • *
  • Posts: 189
Only suggestion I have here is to support the idea of making colonies a more common special feature, especially since the colony feature is split between occupied and abandoned.   Even if colonies are dropped down to 9 and the star league facility options pushed up to 10 and 11 respectively abandoned star league facilities will be more common than either occupied or abandoned colonies while finding occupied star league facilities would be just slightly less likely than finding either type of colony.  Never used anything quite like this but it's already got me making plans for new gaming campaigns.  8)

specter

  • Private
  • *
  • Posts: 28
Oh, I was waiting for you to fill out the second part of the challenge, the impacts on the other parts of the rules. You said you needed some time.

Too bad, I was waiting too  :-[

So, how would this influence the Habitability Modifier and Life Zone Inner/Outer Radii of the Primary Stats Table? Further, how would this influence Step 3: Filling Orbital Slots?

I'm sorry for the size of the following text but you asked for it...  O:-)

An extremely brief overview of planet formation: Terrestrials and giants initially start out pretty similar, as a large piece of rock. Only at a later stage, they begin to differ. At first, the inner planets are (on average) slightly larger because the shorter orbital periods increase planetesimal collision rates but are subsequently unable to gather much gas because the star has already blown away the disk from their orbits, hence, they become terrestrials. On the other hand, the outer orbits are still surrounded by gas which is accumulated by the planets.

So, at some point, the inner planets only grow by collisions with other planetesimals which is a statistical issue, depending on a random initial distribution of disk mass and angular momentum. Thus, their final size / mass can vary statistically. In contrast, the mass of giants is dominated by the accumulated gas which depends on the density of the disk. Since this density decreases with distance to the host star, the outer giants will not gather as much material as the inner ones and cool faster, resulting in the temperature and chemical composition known from ice giants. In the outermost parts of the system the planet formation is extremely slow because the long orbital periods reduce the collision rates between planetesimals to almost zero. For example in our system, the gas disk is gone for 5 billion years now but there are still planetesimals (Pluto etc.) around that have not formed a real planet yet (and will not before the Sun goes boom).

Asteroid belts are another issue. They do not appear at random but are found in unambiguous locations. There are 3 possibilities. One option is extremely far outside of the system where planet formation proceeds so slow that not even planetesimals have formed yet. Another are early planet formation artifacts collected near Lagrange points of planets. The last variant corresponds to our asteroid belt between Mars and Jupiter. The gravitational perturbation from a nearby protoplanet/planet inhibits the formation of any larger bodies there because the orbits are not long-term stable. Such asteroids belts would be scattered out of the system rather quickly but ... (blah blah something about orbital resonance that you don't want to hear). Therefore asteroid belts are found either at the system's rim or in the proximity of a large planet (but outside of its Hill sphere).

In the first billion years, a large number asteroids/comets (mostly made of water ice) from the outer system enter the inner system (due to high eccentricity orbits and scattering) and collide with the planets. Only this way, the inner planets can form a denser atmosphere and eventually oceans.



In the light of this... There is a strict hierarchy with the terrestrials at the inner orbits, gas giants at intermediate orbits and ice giants at the outer orbits. Of course, gravitational scattering could theoretically change this order, however, typically planets are either kicked out of the system or fall into the star. Therefore, a terrestrial planet will hardly be found on an orbit outside of a giant planet. The reason is that the giant would first have to destabilize the orbit of the terrestrial and then, just when the smaller planet is almost ejected from the system, stabilize its orbit again. Winning a lottery is an everyday event compared to these odds.
Because of this I'd recommend to get rid of random assignment of the object types. As replacement one could go for rolling the numbers of terrestrials, gas giants and ice giants which would have to be assigned in the typical order.

Another aspect would be the dependence of planet types on the stellar type. More massive stars form faster and yield a higher luminosity. Therefore, planets would need to form much faster as well. Although it could indeed be faster because of the higher density of protoplanetary disk, the Hill spheres (sphere in which a planet dominates the gravity field) of the protoplanets is also much smaller. This means, that overall mass that can be accumulated before the disk is blown away is most likely smaller. More massive stars are also less likely to have a companion star...
Another problem is the planet formation at larger orbits. Orbital periods are proportional to 1/sqrt(stellar mass) while the stellar luminosity is proportional to (stellar mass)^4. This means that it gets harder and harder to form planets at larger orbits for increasing stellar mass. In this reference, your orbital assignment in Step 2 does quite the opposite (for obvious playability reasons).

The conclusion is that stable planetary orbits will be packed much closer around more massive stars. In addition, more massive stars will have planets in much smaller orbits and are less likely to have Jovian planets. Because the habitable zone drifts outwards and the planet formation zone drifts inwards this also means that habitable planets are less likely to exist. Water transport into the inner system could become a problem because the ice line lies far out and the hot star might evaporate the comets before they can hit the planets. Hence, I would not expect water-rich world.

Vice versa, lower mass stars will likely tend to form planets at larger orbits. The smaller density of the respective protoplanetary disk will slow down planet formation but on the other hand, the star formation takes ages and the disk is not blown away as fast. This could speak for higher numbers of gas giants compared to terrestrials but it is also possible that one end up with hundreds of smaller protoplanets. Also there is a good chance that the habitable zone lies so close to the star that only planetary migration could allow a habitable world but this would require a re-stabilization of the orbit (and seriously why should the mechanism that spirals the planet towards the star suddenly end in a convenient moment). Water transport to the inner planets is probably not a big issue because the ice line is very close to the cool star and the radiation field is weak. Therefore, the likeliness of water-rich worlds is significantly increased.

This brings us to UV, X-rays and Gamma rays. I noticed that you mention their influence on habitability on several occasions. The UV problem for the K stars was a good catch. But there is another interesting influence for the M-dwarfs. These objects show hardly any UV radiation except for strong Lyman-Alpha emission on levels of the Sun. This is interesting because it splits up water (also in form of ice) and releases O_2 and O_3 to the atmosphere (keyword bio-marker). (By the way, there's a typo on p.3 under Life Zone Maximum: replace CO^2 with CO_2). Although oxygen does not yet make a habitable planet, liquid water does neither. But both are good indicators for habitability and, therefore, an ozone layer and sufficient oxygen in the atmosphere can be considered as an extension of the habitable zone beyond the typically assumed orbits.

Of course, the problem is extremely complicated. Realistically, the habitability modifiers that you listed seem too good to be true. I'd expect much more harsh modifiers for non-solar star but that would definitely kill all the fun as well as collide with BT canon.

Anyway, some of the abovementioned stuff could help to set up a more reality-oriented creation mechanism.

Alright, challenge concluded? Or do you have further questions I can help with?

Fallguy

  • Corporal
  • *
  • Posts: 67
  • The FWL: Who says Civil War can't be fun?
Send hearty thanks to "Fallguy" (who hasn't been seen on CBT.com in quite some time) for the Primary Stats table

::blush:: Thanks Cray, but you did all the heavy lifting in making it understandable. All I did was gather stellar data and formulate them into tables and equations. Time consuming, but hot hard.
 
As for being away so long, buying a house, moving, and taking a well-earned vacation is also time consuming. Hopefully I'll have more time available now that we're all settled in.
 
I'd be more than happy to explain the data and where I got it to anyone that's interested. (though you've done quite well at that)
--
"Luke, you're goint to find that many of the truthes we cling to depend greatly on our own point of view."
Obi-Wan Kenobi

Atlas3060

  • ugh this guy again
  • Global Moderator
  • Lieutenant Colonel
  • *
  • Posts: 9387
  • Just some rando
Well Fallguy glad you are back because these rules show why I've been salivating for this book for so long.
When you actually have rules to make your own settings characters themselves, those are good tools for a sadistic overlord GM.
It's not about winning or losing, no it's all about how many chapters have you added to the rule books after your crazy antics.

idea weenie

  • Major
  • *
  • Posts: 4855
Crap, then why is "chasses" passing so many spell checkers?

Is chasses the plural of chassis? Of course my Firefox spellchecker is marking it as incorrect.

From the original note, on p26, referring to production of Medium Lasers and Battlemech chasses, perhaps it is referring to multiple designs being produced.

Sharpnel

  • Colonel
  • *
  • Posts: 13414
'chassis' is both singular and plural
Consigliere Trygg Bender, CRD-3BL Crusader, The Blazer Mafia
Takehiro 'Taco' Uchimiya, SHD-2H Shadow Hawk 'Taco', Crimson Oasis Trading Company

"Of what use is a dream, if not a blueprint for courageous action" -Adam West
As I get older, I realize that I'm not as good as I once was.
"Life is too short to be living someone else's dream" - Hugh Hefner

cray

  • Freelance Writer
  • Major
  • *
  • Posts: 6266
  • How's it sit? Pretty cunning, don't you think?
"All the Pretty Colors", left column, 3rd line from below: Tau Ceti (New Earth in BattleTech) - Not every reader might immediately understand this. To clarify, I suggest to write it Tau Ceti (aka "New Earth" in BattleTech) instead. Btw I think New Earth applies only to the planet, and the sun is still technically named Tau Ceti in BattleTech.

Please note that in the errata thread.

Quote
P. 11, right column, 3rd paragraph: "For the same reason, players should also feel free to declare a planet uninhabitable..." - should presumably read "habitable" instead.

Nope, "uninhabitable" is correct. On p. 11, right column, 2nd paragraph, the guidelines are telling the players to feel free to make a planet habitable. The third paragraph then presents the reverse option: feel free to make terrestrial planets uninhabitable rather than generating continuity-violating numbers of habitable planets.

Only suggestion I have here is to support the idea of making colonies a more common special feature, especially since the colony feature is split between occupied and abandoned.

That's sort of addressed already because the guidelines tell you, "If you want an existing colony on the planet, put it there, don't wait for the random rolls." (Even moving the colony to a more likely number makes them quite rare after all the rolls to see if there's a planet in the life zone, if the planet is habitable, etc.)

Alright, challenge concluded? Or do you have further questions I can help with?

Maybe the challenge was misunderstood. I wasn't asking about background science, but rather specific impacts on the rules. If I'm to rewrite planet placement, I'd like to understand what your suggested change does to the writing in the document. So, my original questions remain: How would this influence the Habitability Modifier and Life Zone Inner/Outer Radii of the Primary Stats Table? Further, how would this influence Step 3: Filling Orbital Slots?
Mike Miller, Materials Engineer

**"A man walks down the street in that hat, people know he's not afraid of anything." --Wash, Firefly.
**"Well, the first class name [for pocket WarShips]: 'Ship with delusions of grandeur that is going to evaporate 3.1 seconds after coming into NPPC range' tended to cause morale problems...." --Korzon77
**"Describe the Clans." "Imagine an entire civilization built out of 80’s Ric Flairs, Hulk Hogans, & Macho Man Randy Savages ruling over an entire labor force with Einstein Level Intelligence." --Jake Mikolaitis


Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.

specter

  • Private
  • *
  • Posts: 28
Maybe the challenge was misunderstood. I wasn't asking about background science, but rather specific impacts on the rules. If I'm to rewrite planet placement, I'd like to understand what your suggested change does to the writing in the document.

Not misunderstood but I presumed you might appreciate to know why things are not realistic. Of course I could have spammed you with a bunch of numbers but would you have trusted them without reason?  ;) By the way, the sentence spelling out the original challenge encompassed only the (200+150)words text. Anything else is a lawyer's rhetoric.  :P

So, my original questions remain: How would this influence the Habitability Modifier and Life Zone Inner/Outer Radii of the Primary Stats Table?

Whatever, let's continue:

The more I think about it, the whole concept of habitability modifiers is not only not necessary but even overly complicated. The current rules require to check whether an orbit lies in the habitability zone anyway. Therefore, the only other influence the stellar classification has on habitability is emission in certain bands that affects atmospheric composition, e.g., the UV issue of K-dwarfs you discuss on page 3. Since this depends on orbital distance, it is completely wrong to roll a composition. Therefore, the whole Habitability Modifiers of the Stars can be easily folded into the effective Life Zone Boundaries which should only contain the range where the planetary atmospheres are dominated by molecular nitrogen. What can be assigned randomly with respect to habitability is the oxygen content of the atmosphere or trace molecules. All other atmosphere compositions of uninhabitable planets are predefined by their distance to the star and the corresponding stellar type. This would simplify the rules and make them considerably more realistic.

Furthermore, it seems useful to expand the Primary Solar Stats Table with columns for the effective planet forming zone. One could go for a single zone but even more convenient would be individual zones for terrestrials, gas giants and ice giants. This way, it is much easier to place the different objects into realistic orbits and it is extremely easy to check where these zone overlap with the habitability zone. The extension of formation zones of the individual planet types would automatically account for higher rates of terrestrials around massive stars and higher rates of jovians around low-mass stars. So again no need to roll.

Water abundance on planets depending on the stellar type would also have to be tabulated in order to account for higher rates of arid planets around massive stars and water-rich planets around low-mass stars. Of course this could be modulated for individual planets via a single roll.

Further, how would this influence Step 3: Filling Orbital Slots?
As I have mentioned before, the assignment of planet types would have to be done before Step 2. A realistic method of creating a system works as follows:
1. Pick a planet type you want to assign.
2. Determine diameter and density according to your Object Type Table.
3. Check the table that tells you in which zone its orbit is legal and put it to an orbit of your choice.
4. Calculate the planet's minimum distance to other planets according to my Step 2 version.
5. Check if any previously assigned planets lies within this minimum distance and whether the new planet lies within the minimum distance of another planet.
    - If true, shift the orbit until no planet lies in the minimum distance of another.
    - If the shifting process pushes the new planet out of the legal orbit range, then the zone must be considered full and the planet must be deleted.
6. Return to 1 until all zones are considered full or move to step 7 if you think to have assigned enough planet.
7. Check which planets lie in the effective habitability zone.
8. Determine water-abundance, traces etc. of the habitable planets.
8. Check table for listed atmosphere composition of the uninhabitable planets and determine traces.
...
Pretty easy to do for the players. Pretty easy to write. The only real challenge is calculating realistic numbers for the tables. Please understand that I avoid to put down numbers before they have a chance to be used.


I just noticed that the listed stellar lifetimes are given with up to 9 digits. However, errors easily reach 50% values. Evolutionary calculations are tricky for a number of stellar types. Therefore only the first two digits bear any real information. All others are just statistical noise. You might consider to set all other digits to 0 which would also improve readability.

Atlas3060

  • ugh this guy again
  • Global Moderator
  • Lieutenant Colonel
  • *
  • Posts: 9387
  • Just some rando
When rolling for moons and such in Step 4, I see on the chart phrases like '2 in 6 chance of rings'.
Does that mean for each moon we roll 1D6 and see if it is a ring?
It's not about winning or losing, no it's all about how many chapters have you added to the rule books after your crazy antics.

cray

  • Freelance Writer
  • Major
  • *
  • Posts: 6266
  • How's it sit? Pretty cunning, don't you think?
When rolling for moons and such in Step 4, I see on the chart phrases like '2 in 6 chance of rings'.
Does that mean for each moon we roll 1D6 and see if it is a ring?

Correct.

Furthermore, it seems useful to expand the Primary Solar Stats Table with columns for the effective planet forming zone. One could go for a single zone but even more convenient would be individual zones for terrestrials, gas giants and ice giants.

Would it be reasonable to phrase the planet forming zone in multiplies of the life zone borders? For example, "The planet forming zone of a star is 0.1x the inner life zone boundary and 100x the outer life zone boundary."
Mike Miller, Materials Engineer

**"A man walks down the street in that hat, people know he's not afraid of anything." --Wash, Firefly.
**"Well, the first class name [for pocket WarShips]: 'Ship with delusions of grandeur that is going to evaporate 3.1 seconds after coming into NPPC range' tended to cause morale problems...." --Korzon77
**"Describe the Clans." "Imagine an entire civilization built out of 80’s Ric Flairs, Hulk Hogans, & Macho Man Randy Savages ruling over an entire labor force with Einstein Level Intelligence." --Jake Mikolaitis


Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.

kato

  • Captain
  • *
  • Posts: 2417
Are the AU values given in various tables, calculations etc throughout the document supposed to always denote orbital radii, or sometimes also orbital distances?

The temperature calculation in particular would fare a lot better if R within this calculation is taken to be the distance between planet and the star's surface - and appropriately reduced by the star's own radius. For regular stars this would be a very minor change to to the calculation (say using (R-0.005 AU) instead of R). In fact, the note on R in the temperature calculation already claims R to be the "planet's orbital distance from the primary in AU".

Background is that this becomes interesting when dealing with bloated giant stars of significant radii. Experimentally bloated out a M0V subdwarf to a M0Ia supergiant - with a rather huge stellar radius of 200 R⊙. This results in the bloated star swallowing all inner Titius Bode orbit positions up to orbit 5, leaving whatever is in orbit 6 a scant 6 million km above the star's surface. Not a stable position of course, but let's leave that aside for a moment. Ignoring the bloating for the safe jump distance results in our zenith/nadir jump points still remaining some 30 million km above the surface btw. The star has swallowed its own habitable zone as defined per the document, quite fine to me.

The above note on the temperature calculation is important when looking at that planet in orbit 6, a giant terrestrial probably about to be swallowed by the star within a few dozen years. Assuming its atmosphere to be long blown away leaving a vacuum (and i actually rolled that!), this planet, using the standard temperature calculation, has a surface temperature is -45°C on the day side.
Using the adapted calculation above it has a surface temperature of 1163 K if we reduce R within the temperature calculation by the star's own radius. 1163 K means the planet mostly consists of half-molten basaltic lava at the surface, a rather nice image for such a planet about to hurl itself into a star.

When rolling for moons and such in Step 4, I see on the chart phrases like '2 in 6 chance of rings'.
Does that mean for each moon we roll 1D6 and see if it is a ring?
Correct.
Perhaps we need some kind of definition of what constitutes a "ring formed instead of a small moon", a "ring formed instead of a medium moon" etc then? Perhaps regarding width and/or density of this ring, possibly by rolling out a moon's density and diameter and some kind of standard conversion from this?

specter

  • Private
  • *
  • Posts: 28
Would it be reasonable to phrase the planet forming zone in multiplies of the life zone borders? For example, "The planet forming zone of a star is 0.1x the inner life zone boundary and 100x the outer life zone boundary."

Sure, why not. It doesn't matter whether you use absolute or relative "coordinates".

cray

  • Freelance Writer
  • Major
  • *
  • Posts: 6266
  • How's it sit? Pretty cunning, don't you think?
Sure, why not. It doesn't matter whether you use absolute or relative "coordinates".

What proportions would you recommend? 0.1x Inner Life Zone Radius and 100x Outer Life Zone Radius or something else?
Mike Miller, Materials Engineer

**"A man walks down the street in that hat, people know he's not afraid of anything." --Wash, Firefly.
**"Well, the first class name [for pocket WarShips]: 'Ship with delusions of grandeur that is going to evaporate 3.1 seconds after coming into NPPC range' tended to cause morale problems...." --Korzon77
**"Describe the Clans." "Imagine an entire civilization built out of 80’s Ric Flairs, Hulk Hogans, & Macho Man Randy Savages ruling over an entire labor force with Einstein Level Intelligence." --Jake Mikolaitis


Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.

kato

  • Captain
  • *
  • Posts: 2417
When rolling for moons and such in Step 4, I see on the chart phrases like '2 in 6 chance of rings'.
Does that mean for each moon we roll 1D6 and see if it is a ring?
Correct.
Just to repeat this question? Seriously?

Meaning for a single gas giant i'd have to roll up to 50 (fifty!) D6 adding and subtracting moons and rings?

specter

  • Private
  • *
  • Posts: 28
What proportions would you recommend? 0.1x Inner Life Zone Radius and 100x Outer Life Zone Radius or something else?

Since the problem is depending of the characteristics of the star, it requires 2 values per spectral type.
Also, I conclude from your question that your approach requires that the life zone and the planet formation zones will have an intersecting set. This is most likely not going to be true for the highest and lowest mass stars, where the habitable zone will too far outside and too far inside, respectively, to overlap with the planet forming zone.

Therefore, it seems more realistic to expand the Primary Solar Stats Table with 2 additional columns for (each of) the planet forming zone(s) limits. The question is, whether your assigned page-space would allow for an expanded table. I'd expect the overall text requirements to explain the more realistic system to shrink, so it seems feasible.

Anyway, in case that you would like to create such a table for the planet formation zone(s), I could calculate the required data for you and/or provide you with the required equations...



PS: As the previous lines probably revealed, I would personally still go for individual formation zones for terrestrials, gas giants and ice giants. This way the players would not need to mess too much with the positioning of the individual types. Of course, rule #1 ("Ignore the rules if it isn't fun.") would always apply and allow for a broader diversity if players wish.

kato

  • Captain
  • *
  • Posts: 2417
PS: As the previous lines probably revealed, I would personally still go for individual formation zones for terrestrials, gas giants and ice giants. This way the players would not need to mess too much with the positioning of the individual types.
That can actually be realized by simply shifting the possible rolls of a 2D6 on a sliding scale as you go outwards.

The current ruleset shows a preponderance for terrestrial planets in the life zone (30.55% probability for terrestrial, 13.88% for giant terrestrial, 19.44% for gas giant, 8.33% for ice giant), and outside the life zone simply twists this towards gas giants (30.55% probability for gas giant, 13.88% for giant terrestrial, 19.44% for terrestrial, 19.44% for ice giant).

Just set up the roll table so it effectively creates the wanted probabilites for the orbit you are in, probably expanding it to 2D6 on a virtual 5D6 (x<5..25<x) set. You can reasonable set this up for up to 66.66% chance (five following numbers on the 7+n center) for the desired kind of object in an orbit.


On a side note, the probabilities of "asteroid belts" in the outer system is too low in the current rules. Just look at Sol, we have four separate asteroid belts in the system (5th orbit, scattered disc, Kuiper Belt, Oort cloud).

cray

  • Freelance Writer
  • Major
  • *
  • Posts: 6266
  • How's it sit? Pretty cunning, don't you think?
The current ruleset shows a preponderance for terrestrial planets in the life zone (30.55% probability for terrestrial, 13.88% for giant terrestrial, 19.44% for gas giant, 8.33% for ice giant), and outside the life zone simply twists this towards gas giants (30.55% probability for gas giant, 13.88% for giant terrestrial, 19.44% for terrestrial, 19.44% for ice giant).

Ooo, someone noticed.

I'll work on increasing the possibilities of asteroid belts.
Mike Miller, Materials Engineer

**"A man walks down the street in that hat, people know he's not afraid of anything." --Wash, Firefly.
**"Well, the first class name [for pocket WarShips]: 'Ship with delusions of grandeur that is going to evaporate 3.1 seconds after coming into NPPC range' tended to cause morale problems...." --Korzon77
**"Describe the Clans." "Imagine an entire civilization built out of 80’s Ric Flairs, Hulk Hogans, & Macho Man Randy Savages ruling over an entire labor force with Einstein Level Intelligence." --Jake Mikolaitis


Disclaimer: Anything stated in this post is unofficial and non-canon unless directly quoted from a published book. Random internet musings of a BattleTech writer are not canon.

specter

  • Private
  • *
  • Posts: 28
That can actually be realized by simply shifting the possible rolls of a 2D6 on a sliding scale as you go outwards.

On the first look your suggestion seems okay. Nonetheless, it does not seem necessary to make random rolls at all. The chance to form a giant with a smaller orbit than a terrestrial is effectively zero. The chance to subsequently scatter a terrestrial into an stable orbit outside of a giant's orbit without ejecting the terrestrial is likewise negligible. The current set-up guarantees that there is huge probability to have a giant planet on a smaller orbit than a terrestrial:
number of planets:
probability (inside life zone):
probability (outside life zone):
2
12%
17%
3
21%
25%
4
28%
29%
5
32%
32%
...
...
...
Therefore, a significant fraction of the created systems will be unrealistic. Of course, your suggestion could effectively eliminate this problem but on the other hand it would automatically become pointless if all slots that a modified roll could hit would contain the same sort of object, i.e., only terrestrials or only giants...

On a side note, the probabilities of "asteroid belts" in the outer system is too low in the current rules. Just look at Sol, we have four separate asteroid belts in the system (5th orbit, scattered disc, Kuiper Belt, Oort cloud).

The outer asteroid belts are effectively the remnants of planet formation and will probably exist is some form or another around mostly every star. Unfortunately, they are mostly composed of water ice. Hence, it does not make sense to establish a colony there, because the heat from the colony would evaporate the water around it. So either the colony would sink into the core if placed on larger ice blocks or would soon float through open space as it melts away all material of smaller blocks. In addition, the surface gravity on these asteroids is negligible and the distance to any colonies that could provide industrial items is huge. So why even bother with these asteroid belts.

On the other hand, asteroid belts like the one between Mars and Jupiter is something that could appear everywhere close to orbits of larger planets (but outside of the Hill sphere). Therefore it is not too problematic to create a random rolled probability to have an asteriod belt near a planet orbits. One could even think of a modifier, depending on planet types. Anyway, asteroid belts should be assigned after all planets and their orbits have been assigned.

worktroll

  • Ombudsman
  • Colonel
  • *
  • Posts: 25570
  • 504th "Gateway" Division
    • There are Monsters in my Sky!
The outer asteroid belts are effectively the remnants of planet formation and will probably exist is some form or another around mostly every star. Unfortunately, they are mostly composed of water ice. Hence, it does not make sense to establish a colony there, because the heat from the colony would evaporate the water around it. So either the colony would sink into the core if placed on larger ice blocks or would soon float through open space as it melts away all material of smaller blocks.

Thinking flatlander there, Specter! Consider - that negligible gravity means there's no reason for the base to sink into the ice. While you'd get some localised melting, water is itself a useful insulator/heat sink. There'd be little or no pressure moving the base away, and surface tension might even resolve the problem.

If you absolutely must be fixed on the ice, metal rods driven into the ice, topped by heatsinks or equivalent, topped by your base, will work fine.

Why base off an ice asteroid? It's the ultimate filling station in deep space. Oxygen, hydrogen & water with no gravity well to speak of preventing it getting to nearby ships.
* No, FASA wasn't big on errata - ColBosch
* The Housebook series is from the 80's and is the foundation of Btech, the 80's heart wrapped in heavy metal that beats to this day - Sigma
* To sum it up: FASAnomics: By Cthulhu, for Cthulhu - Moonsword
* Because Battletech is a conspiracy by Habsburg & Bourbon pretenders - MadCapellan
* The Hellbringer is cool, either way. It's not cool because it's bad, it's cool because it's bad with balls - Nightsky
* It was a glorious time for people who felt that we didn't have enough Marauder variants - HABeas2, re "Empires Aflame"

The Hawk

  • Warrant Officer
  • *
  • Posts: 473
  • Have talons, will travel.
Ooo, someone noticed.

I'll work on increasing the possibilities of asteroid belts.

I had the same concern.  The +2 on the Object Type Table shoves everything toward gas and ice giants at the expense not only of asteroid belts but also of dwarf terrestrials (as the text indicates, intended to include Pluto, and presumably similar (and apparently real-world common) trans-Neptunian objects like Sedna and Eris) and empty space (impossible to roll past the habitability zone).  This seems to have significant consequences for small stars with large numbers of orbital slots (like this M2V I'm rolling with 13 slots, only the first one of which is in the life zone) that will, on average, be littered with more gas and ice giants than larger and more habitable stars.  While offered with the caveat that I am not up to speed on the latest extrasolar system observations around small, cool stars, that just doesn't seem right.

The easiest solution may be to bookend the table at the 11+ end with additional lines for dwarf terrestrial, asteroid belts, and empty space, and possibly further (if justified by the science) giving rolls on that table an additional positive modifier for small stars.

 

Register