The "safe jump distance" is actually well within the sun here! As is the assumed life zone orbit.
Okay, and here's my personal gripe: Transit times.
What's the point in investing a great deal of effort into a scientifically accurate simulation/description of a realistic star system, only to laugh at all the data and then use that overly simplified travel time diagram from DS&JS? The one that treats all stars as main sequence stars no matter what?
The document skips around this by being semi-honest and featuring only (V)-subclass stars. But really, what I would dearly love to see is going full monty and taking the actual size of the sun into consideration.
Factual error: The Oort Cloud is not a belt, and it's even highly arguable whether it can be described as asteroids. And it definitely doesn't occupy an orbital slot - its very nature is being a cloud of matter outside of the accretion disk and outside of the orbits. In a sense, it's not even part of the system anymore.
On another topic, this issue should've been raised here first rather than posed as an errata:Sorry; I figured it was a factual error and should go into errata instead (again, precisely because Randall wrote above that this thread isn't meant for errata).
The inner Oort Cloud is hypothesized to be donut-shaped - a belt. Furthermore, as soon as I left out provisions for including the Oort cloud, another player would ask how to make it. Thus, the compromise was to address the (inner) Oort Cloud as an "asteroid" belt and note in the text that the "asteroids" might, in fact, be "icy outer system" objects.
I guess I'm in the minority, but I was bored out of my skull reading it. Math, equations and the likes are... well not something I enjoy in my spare time.
For those folks, the A Time of War Companion has the "quick start" version of system creation. You roll some dice and get quick results without the boring discussion or math.
It seems odd to me that Star league facilities are more common than Colonies... are there any plans to provide alternate era versions of the special features chart?
I can look into juggling results of the table. I'm not sure how much room for expansion and extra tables there is.
Not a problem, it was anticipated not everyone would prefer these in-depth system generation rules. For those folks, the A Time of War Companion has the "quick start" version of system creation. You roll some dice and get quick results without the boring discussion or math.I....I just love you all for making this.
ATOW:Companion is available for purchase by download now if you'd prefer to try out that system.
For the "additions wishlist," can something brief, maybe even just a few lines long, be inserted to differentiate between "not easily inhabitable" and "truly uninhabitable?"
I....I just love you all for making this.
Are you guys going to do open beta on other parts of this book too?
Modifiers are cumulative; a colony of 100,000 would apply both +1 for a population of under 100 million and +1 for under 100,000 .If I read the tables correctly, that final modifier should be for under 1 million, not under 100,000.
Not sure if an error or deliberate: Are the life zones for some stars supposed to have exactly zero chance of having an orbit fall within them? Rolled up an M6V, only to discover that the first orbit started at 0.08 AU and the life zone ended at 0.079.
It should also be noted that the incidence of habitable
planets using this chart is far above the norm for BattleTech
(which is about 1 habitable planet per 1,000 systems in the
Inner Sphere), let alone reality. This is done for playability.
Awesome work!
pg. 25 when explaining how to work the modifiers:If I read the tables correctly, that final modifier should be for under 1 million, not under 100,000.
Hope it helps!
Thank You
- Shane
Not sure if an error or deliberate: Are the life zones for some stars supposed to have exactly zero chance of having an orbit fall within them? Rolled up an M6V, only to discover that the first orbit started at 0.08 AU and the life zone ended at 0.079.
Anyone else having a big headache with the year length calculation.
My Scientific calculator refuses to understand the example...
I'm going to go away and see if I can now generate stats for Mummerset, the planet my BattleTech campaign is set on and see if they produce something that works for my Dark Age periphery campaign.
Yep. Please report that in the errata thread.
I can fiddle with the base orbital diameters, but the rules was working with G and F-type stars. Have you found any other stellar types (other M sub-types, K, G, F, etc.) whose life zones don't match up with the planet orbits?
[edit] Looks like Mukaikubo has checked others. I'll go through and tweak the orbital diameter results to get a planet in the life zone.
T = 2 x Pi x sqrt [R^3 / (G x M) ]
In the pg8 example, you've got a star with a mass of 3x10^30 kg, a gravitational constant of 6.674x10^-11, and a planetary orbital radius of 3.6x10^11 meters. Filling out the equation:
T = 2 x Pi x sqrt [3.6 x 10^11^3 / (6.674x10^-11 x 3x10^30) ]
Per the order of operations, taking care of the paranthetical terms first:
R^3 = (3.6 x 10^11)^3 = 4.6656x10^34
(G x M) = (6.674x10^-11 x 3x10^30) = 2.0022x10^20
And then divide those two, completing the work inside the parentheses:
[R^3 / (G x M) ] = [ 4.6656x10^34 / 2.0022x10^20] = 2.3302x10^14
Then you apply the square root:
sqrt [R^3 / (G x M) ] = sqrt (2.3302x10^14) = 15,265,133
Then you multiply by 2 and Pi:
T = 2 x Pi x sqrt [R^3 / (G x M) ] = 2 x Pi x 15,265,133 = 95,913,533 seconds
And to convert seconds to years:
95,913,533 / 31,536,000 = 3.04 years
How are you applying parentheses in your calculator? I've attached a picture on my TI-85 of how I set it up.
Was using a scientific calculator program for windows. Speed Crunch. Everything else seemed to work... lemme see if I can find what I entered..
2*3.14159*sqrt((3.6e11)^3/(6.674e11*3e30)) I think this is the first time in my life I have ever used scientific notation. Star is multiply by and it spits out 0.00095913452505037542.
Every other calculation I have had to do has worked...
Nope. 9.59134ect ect
Well, sir, I'm not sure what's happening. I can exactly replicate your incorrect answer by plugging 6.674e11 into the calculator I showed earlier. When I insert 6.674e-11, I get 95 million-ish. Are you able to provide some screen shots of your calculation with 6.674e11 and 6.674e-11 in them?
sqrt [R^3 / (G x M) ] = sqrt (2.3302x10^14) = 15,265,133
Read it cover to cover. Haven't run numbers but on read through found it so appear reasonable enough. I did find the writing styles to be a little jolting. Perhaps an odd thing, but when reading the scientific part it was reasonable formal, and then Chuck's examples came across as very informal. Perhaps I've been reading too many journals. And again, I'm not sure why, but Chuck seemed like the wrong name. No offence to the Chucks of the world but that named seemed like the naming equivalent of X.
Edit 2: Ok... got it. Finally! I really hate calculators. Thank you very much for your help.
If you feel so inclined to capture your trials and travails with screen shots and post them here (or in PMs), I'd appreciate it. If you have trouble, someone else probably will, and the more experience I get at answering problems the smoother these rules will work out. Beta testing is about capturing that experience.
Scientific Notation. No, seriously. I kept missing it when it appeared and not recognising the symbols. I brain derped.
I've attached a picture on my TI-85 of how I set it up.
According to simulations brown dwarf masses can go down to about 1M_jup.I'm somewhat out of my depth here, but I recall reading that Jupiter's albedo is higher than it should be, suggesting it may actually be emitting light in addition to reflecting sunlight.
Cray, I always figured you for an HP48 man ;)
p.21 Titius Bode Law: This law has been proven to be nonsense.
One can take a function with roughly as many variables as there are data point in a given observation/measurement and one will find a perfect match.
p.21 Water, Water Everywhere:
Have you considered to add a paragraph on water migration after planetary formation? Simulations have shown that hydrogen is driven out of the inner system rather quickly in the early phase. This is also the reason why Terrestrials are typical in the inner system while mid-distance planets gather much more gas, hence turn into gas giants. Ice giants result from gas being driven out before a full gas giant has formed, because the orbital periods in the outer system are much longer than in the intermediate range. The interesting thing about water on the Terrestrials is that it need to be transported there via comet or asteroid impacts. In simulations, this has proven to work rather good for solar-like stars. However, X-ray active stars dissociate water at much larger distances, which allows the hydrogen to be driven out of the system. In other words, the required ice comets and asteroids can not form as efficiently. Therefore, such systems will rarely feature habitable planets because the water is not only necessary for the oceans but also for oxygen enrichment in the upper crust and atmosphere. On the other hand, presuming that water is already present on a planet, the X-rays can accelerate the oxygen enrichment of the atmosphere, therefore, also accelerate the bio-cycle and evolution. This is a mechanism that could cause more habitable planets around M-dwarfs than one would expect from the first glance.
I'm somewhat out of my depth here, but I recall reading that Jupiter's albedo is higher than it should be, suggesting it may actually be emitting light in addition to reflecting sunlight.Careful! The excess radiation is easily explained and does not imply that Jupiter is brown dwarf.
Here's your challenge, should you choose to accept it. Come up with a scientifically correct replacement for Step 2: Placing Orbits and the Orbital Placement Table that is no longer than 200 words. (Microsoft Word has a handy word counting functions.) You have an additional 140 words to provide an example of Chuck laying out the star system according to your new rules.
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 suppose I will be allowed to replace the table with one of similar size?
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?
T = 2 x Pi x sqrt [R^3 / (G x M) ]
In the pg8 example, you've got a star with a mass of 3x10^30 kg, a gravitational constant of 6.674x10^-11, and a planetary orbital radius of 3.6x10^11 meters.
I got annoyed by the extra terms, and converted the above equation to:
T = k * sqrt (R^3/M)
Then solved for k:
k = 2*pi / sqrt(G)
k = 2*pi / sqrt(6.674e-11)
k = 2*pi / 8.169e-6
k = 769107
This way you don't have to worry about figuring out all the equations, you just plug in two numbers, cube one of them, divide it by the other, take the square root of the result, and multiply it by a single constant. Same equation, just much simpler to use.
Yep. Please report that in the errata thread.
I can fiddle with the base orbital diameters, but the rules was working with G and F-type stars. Have you found any other stellar types (other M sub-types, K, G, F, etc.) whose life zones don't match up with the planet orbits?
[edit] Looks like Mukaikubo has checked others. I'll go through and tweak the orbital diameter results to get a planet in the life zone.
T = 2 x Pi x sqrt [R^3 / (G x M) ]
In the pg8 example, you've got a star with a mass of 3x10^30 kg, a gravitational constant of 6.674x10^-11, and a planetary orbital radius of 3.6x10^11 meters. Filling out the equation:
T = 2 x Pi x sqrt [3.6 x 10^11^3 / (6.674x10^-11 x 3x10^30) ]
Per the order of operations, taking care of the paranthetical terms first:
R^3 = (3.6 x 10^11)^3 = 4.6656x10^34
(G x M) = (6.674x10^-11 x 3x10^30) = 2.0022x10^20
And then divide those two, completing the work inside the parentheses:
[R^3 / (G x M) ] = [ 4.6656x10^34 / 2.0022x10^20] = 2.3302x10^14
Then you apply the square root:
sqrt [R^3 / (G x M) ] = sqrt (2.3302x10^14) = 15,265,133
Then you multiply by 2 and Pi:
T = 2 x Pi x sqrt [R^3 / (G x M) ] = 2 x Pi x 15,265,133 = 95,913,533 seconds
And to convert seconds to years:
95,913,533 / 31,536,000 = 3.04 years
How are you applying parentheses in your calculator? I've attached a picture on my TI-85 of how I set it up.
Chuck is an occasional gamer in my BT group with a masters in space systems engineering (aka rocket science), an affinity for Edgar Rice Burroughs novels, and a laid back attitude that seemed perfect for capturing the beer-n-pretzels origins of BT. He is exactly the kind of guy who would write a report on the navigation of an interplanetary probe addressing multi-body gravity effects, sunlight pressure, radiant heat releases, and probe outgassing in the informal tones used in the examples of these system/colony generation rules.
, I thought the example text served to take the edge off the severely formal rules text. The contrast might be a bit jarring, but the idea was to show that applying the system/colony generation rules didn't require rigid scientific formality but could instead conform to the needs of gamers. They are guidelines, after all, not rules that will cause the game police to storm into your home and lash you with wet noodles for improvising outside the dice rolls. ;)
I got annoyed by the extra terms, and converted the above equation to:
T = k * sqrt (R^3/M)
Then solved for k:
k = 2*pi / sqrt(G)
k = 2*pi / sqrt(6.674e-11)
k = 2*pi / 8.169e-6
k = 769107
One idea that came to me after doing this process a few times: could you possibly include a page that just contained all the calculations used in the process? You know, something of a "cheat sheet" for quick reference?
Cray, I have a question on a few things I didn't see in the I.O. open Beta test. First is System Quirks, followed by what kind of quirks? Some examples being; Solar Flares, Background Solar Winds, Background Solar Radiationand Elliptical Orbit Objects. What are you'r thoughts?
Sorry, nitpick
Pg. 11 very top of right hand column of text - Terrestrial Planets: - is not in bold text like the other headings.
Thank You
- Shane
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)
Crap, then why is "chasses" passing so many spell checkers?
Nope, that doesn't apply to Google Chrome's spellchecker, only MS Word. It seemed to follow a pattern: axis, axes; basis, bases; chassis, chasses.
In fact, I just went over to a computer with a never-used-before copy of MS Word 2010 and its unmodified spellchecker passed chasses.
So what's chasses mean, if it's a valid word?
Calculating the km distance, using the approximate AU value provided of 150 million kmThe 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.
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?Hmm, guess so, now that you're pointing it out. Life Zone Position Modifier for M2V should be 0.72916667 then?
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?
Yep.
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
Umm, don't you simply call that option "Eccentric Planetary Orbits" on p. 19?
Any chance, that my response to your challenge has been overlooked and not just ignored? :(
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...
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).
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.
Would you like these posted to the errata?
Hmm, guess so, now that you're pointing it out. Life Zone Position Modifier for M2V should be 0.72916667 then?
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.
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?
Send hearty thanks to "Fallguy" (who hasn't been seen on CBT.com in quite some time) for the Primary Stats table
Crap, then why is "chasses" passing so many spell checkers?
"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.
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.
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.
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?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:
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?
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.
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?When rolling for moons and such in Step 4, I see on the chart phrases like '2 in 6 chance of rings'.Correct.
Does that mean for each moon we roll 1D6 and see if it is a ring?
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".
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?
What proportions would you recommend? 0.1x Inner Life Zone Radius and 100x Outer Life Zone Radius or something else?
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).
That can actually be realized by simply shifting the possible rolls of a 2D6 on a sliding scale as you go outwards.
|
|
|
|
|
|
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.
Ooo, someone noticed.
I'll work on increasing the possibilities of asteroid belts.
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.
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?
Actuallymostall trans-neptunian dwarf terrestrials are part of thethreetwo (not including Oort Cloud) outer "asteroid belts". Pluto itself is one such dwarf planet in the Kuiper Belt, Eris and Sedna are usually tagged a part of the Scattered Disc. There are only about two dozen known objects beyond Neptune not part of either, all well below 100 km diameter.
Just noticed: There is a distinct gap in size between dwarf terrestrials (max 2200 km diameter) and terrestrials (min 2700 km diameter), making it impossible to roll for an intermediate planet.
Distribution of Moons, page 10: suppose there are six small moons and two medium moons. Medium moons at 50 and 100; small moons #1-#4 at 10, 20, 30, and 40; small moon #5 at 150 from being bumped by the medium moons. Does small moon #6 go to the next normal small moon slot (60,000 km) or the next small moon slot after #5 (160,000 km)?
Variable stars, page 21: No mention made of long-term variable stars going back to their default luminosity after increasing.
Does the luminosity increase in a sudden spike, a sort-of bell curve, or a constant increase?
Spectre, what's a recommended range of planet forming regions for the different stellar types?
Give me some time to set up some equations for an educated guess. Would you prefer a post here or a personal message? I'll also add the reasoning for equations because I presume you would like to know some details.
Having the formula for population growth so that the population's expansion or decline for a colony could be tracked as well as a random table of events that could affect a colony would be useful.
A post here is fine, so it can be discussed with other players.
Okay, here's the promised table (appended). For selfconsistence, it also contains respective stellar data. The columns corresond to: spectral type, effective temperature, mass, radius, luminosity, nuclear timescale, rockline, iceline, outer planetesimal formation limit, inner habitability zone limit, outer habitability zone limit.
Okay, here's the promised table (appended). For selfconsistence, it also contains respective stellar data. The columns corresond to: spectral type, effective temperature, mass, radius, luminosity, nuclear timescale, rockline, iceline, outer planetesimal formation limit, inner habitability zone limit, outer habitability zone limit.
Terrestrial cores form between the rockline and iceline while Jovian cores form between the iceline and the outer formation limit. Of course, planetary migration can change the initial orbits considerably and clearly far beyond the given limits. For instance, our two ice giants have been pushed out of the zone of effective planetesimal formation...
Note that the habitability zone is cut off for spectral types earlier than A8 because hard radiation and stellar wind ionize and subsequently blow away the atmospheres of habitable candidates. Likewise, the habitability zone effectively ceases with type L4, because it leaves the zone of effective planet formation. Well, technically that does not exclude a habitable planet around later spectral types but it makes them much less likely.
but that only means we haven't yet seen one that breaks the theories.Eh, that has happened. They just managed to form halfway plausible planetary migration theories to account for Hot Jupiters.
How do you determine how far from Terra a colony is?
Has anyone considered how to determine the current age of the generated star system, or is it assumed that the system is 1/2 way through it's life cycle?
That's impressive work. Thank you. I look forward to seeing your discussion on the calculations and assumptions
Honestly, your chart is beautiful. I would much rather have the system incorporate fully realistic orbital dynamics, but honestly current theory on planetary system evolution is nearly as much guesswork as it is research and proofs, ...
Eh, that has happened. They just managed to form halfway plausible planetary migration theories to account for Hot Jupiters.
Has anyone considered how to determine the current age of the generated star system, or is it assumed that the system is 1/2 way through it's life cycle?I considered to include something in that direction but time limitations have prevented it so far. Habitability zone, stellar parameters and orbits vary with age, even on the main sequence.
separate cardstock?Separate would be ideal. Perhaps with other tables on the back. I do a lot of moving back and forth through the pdf when looking up some star data in later calculations (e.g. luminosity).
For the record, I was ordered at editorial gun point ;) to give a faint chance for habitability on the Primary Stats Table to bright stars (hence the very high penalties in A and B-class stars. Most of my drafts had a cut-off ("Not habitable") for stars with lives too short to really get a good ecosystem (or even planets) going.
...According to Kaltenegger et al.(2009), evolution to higher lifeforms could proceed on timescales of 10 million years...
I haven't yet found that particular article, ...
The article I found looks like the revision of the original 2009 paper. Maybe Kaltenegger changed her mind?
I'm late to this party, but will hopefully be able to read through the pdf over the next couple of days. Is there a close date for feedback?
One thing might be a complete redo of the USIIR (http://www.sarna.net/wiki/USIIR) codes.
I had a thought while reading Interstellar Expeditions: are there plans to include information on terraforming planets? For example, how much time might be needed to bring a planet up one step on the HABITABLE PLANET FEATURES TABLE on page 14, what kind of cost, equipment, etc. are needed, and what are possible complications/failures that might arise during the process?
And one more suggestion for the rules: It is easy to create a table that lists minimum planetary radii that are necessary to maintain critical species (w.r.t. habitability) in the atmospheres.
The background of this is simply the fact that planets require a minimum radius/mass for a given surface temperature in order to have thermal gas velocities below the escape velocity.
I'm hoping to have a revised edition back to the bosses by the end of next week. If you don't make me re-write large tracts of the rules, then you've got until at least the end of Sunday.Thanks, Cray! I should definitely have something by then, probably more for the errata thread than this one, so no worries on re-writing large tracts of rules. My last astrophysics course was almost twenty years ago now, but most of what specter (and Kaltenegger) was talking about is still intelligible.
Of course, by then another chapter is going up for public comment that I'm responsible for, so that'll be some multi-tasking.
...
Now that's an interesting idea. BattleTech seems to be very quick about terraforming, being able to terraform Venus and Mars to basic habitability in about 100-150 years. (Reasonably, other projects would generally be in terms of 25 to 75 years.) However, JHS:Terra also notes they were some of the most epic engineering endeavors by mankind (the tonnage of nitrogen, water, and calcium needed to be delivered to Mars and Venus is best described with exponents or fractions of Titan's mass) and most other terraforming efforts around the Inner Sphere are smaller.
I think the places the idea would break down is costs, logistics (tonnages of equipment required), and trying to set numbers to the tonnages of water and oxygen or nitrogen to be added (or removed) from planets. BattleTech's economics are not set up to handle trillion- or quadrillion-CB projects. Its merchant stellaris is in shambles for most common eras of play (so importing giant "atmosphere processors" or other mega-engineering equipment is hard). Existing, well-described space transports (DropShips) are poorly suited for moving teratons of water or other useful terraforming materials.
In short, terraforming rules open several cans of worms. It's easier to let players designate a planet as having been terraformed, particularly when the system generation rules note the star or planet is unlikely to pass a habitability roll.
Thanks, Cray! I should definitely have something by then, probably more for the errata thread than this one, so no worries on re-writing large tracts of rules. My last astrophysics course was almost twenty years ago now, but most of what specter (and Kaltenegger) was talking about is still intelligible.
Terraforming is already addressed in Era Report: 2750. Did you want something other than those guidelines?
Cray, I've just started my detailed read through, but I must say the scientist in me cheers at the carefully crafted caveats in the language. The gamer in me cries, however. I think there's a happy medium that I'll shoot for in my recommendations.
On the IO operations, I think that the far colony numbers may be low-- and high. That is to say, that I would expect that a colony world more than 1500 LY away, and beyond any support has either prospered, or become a completely failed colony especially if its old. A borderline colony would have too many opportunities for events to push them over to the level of non-viability.
If I'm reading everything right a M6V star can never have a planet in the life zone unless you monkey with the life zone.
As far as I can tell that is the only outlier.It is; the previous discussion is on the first or second page.
I already factored escape velocity into habitability and atmosphere thickness. Did you want a different, more detailed approach than just escape velocity?
Mostly for my own information I've calculated the minimum and maximum gravity of Dwarf Terrestrials, Terrestrials, and Giant Terrestrials. I am a little unsure about how low the maximum gravity for Giant Terrestrials seems to be but I'm not a scientist and my knowledge of astronomy is little above layman so it could be just fine. *shrug*
The Life Zone Position Modifier I'll have to take a closer look at the errata and perhaps even the earlier discussion to see if this has already been addressed but it does seem counter intuitive to me that the farther away from the sun in the life zone provides a better positional modifier. Shouldn't being closer to the middle of the life zone be best?
Remember that as the world gets bigger the lower the gravity gets, the distance between the person and the CENTER of the planet effects surface gravity, also centrifugal force SHOULD mean that as the planet spins faster apparent surface gravity should decrease
Perhaps inserting a fiction piece in IO from the point of view of a DoME engineer would be a good way to do it without creating rules for it.Yes do this please! That fluff piece alone would help convince at least 3 non-players to buy IO.
Depending on their size, giant terrestrials can have surprisingly low densities that likewise lower surface gravity. Taken to extremes, you find that Saturn (100x Earth's mass) and Uranus have surface gravities equal to or less than Earth's. A low-density giant terrestrial can likewise have relatively low gravity despite high mass.
Remember that as the world gets bigger the lower the gravity gets, the distance between the person and the CENTER of the planet effects surface gravity, also centrifugal force SHOULD mean that as the planet spins faster apparent surface gravity should decrease
Has there been any thought of adding a modified "Colonization/Settlement-Friendly" way to determine the diameter/density for an inhabitable terrestrial planet that gives a less realistic distribution of gravity for planets in general but one that is more likely to have been chosen for colonization? I.e. the typical IS planet is not going to have .6 gravity, some inhabited planets might but they'd be in the vast minority, most I would expect to be in the range of .9 to 1.1 or at the very least .8 to 1.2 (the 2nd group based on the population penalties for anything above/below .8/1.2).
In my case I'm working on generating planetary data for MekHQ for pretty much all of the published systems/planets that do not have canon data and I'm finding that if I use the current method I end up with a lot of planets outside of the typical range that would have been colonized (i.e. less than 16% of results fall between .9 to 1.1 or 30% fall between .8 to 1.2, meaning 70% of results are outside of the relatively comfortable zone). The current method certainly gives a more realistic distribution of gravity for terrestrial planets but not so much for planets that would support regular settlements.
Well, I can impose a habitability penalty on planets with gravity outside the comfort zone. Could you show the break down of results by dice rolls that you're getting?
Transit Distance = √[(Distance A)2 + (Distance B)2]
Time = 2 x square root (Distance / Acceleration)
Where:
Distance A = .43 AU (according to page 86 of SO) * 150,000,000,000 m
Distance B = .7 (mass of the Primary) * .7 AU (base location for Orbit 2) * 150,000,000,000 m
Try again with "A" as 433,890,326,000 meters and let me know what you get.
pg. 29 under the heading Exceptions lists the average Inner Sphere planet as having a population of 3 billion.
That was written before Herb laid down a new law. :)
Cool, I always thought the BT population was too large on most planets! I mean, did colonization packages include Viagra or something? >:D
I had always assumed that the Collapse of the Star League > Third Succession War period accounted for a significant increase in mortality as support systems broke down and the sphere degenerated into some fairly dirty wars.