I haven’t posted any new Architect of Worlds material for a few days, but the project is still moving forward. The main issue is that I’m being required to ramp up my day-job telework to full-time status, so I need to make some adjustments to my time management. That’s being worked out, so I should be able to make progress on several of my creative projects over the next couple of weeks.
To review the bidding: since early September, I’ve written and posted the first drafts for Steps Fifteen through Twenty-Three of the design sequence. At this point, the reader should be able to get some of the broad outlines of a generated world’s surface conditions: blackbody temperature, the prevalence of water, geology, and some information about the composition and density of the atmosphere.
What’s left? Well, we still need the world’s actual surface temperatures, the prevalence of dry land if the world has oceans, the final composition of the atmosphere, and the presence and complexity of native life.
There are some complex interdependencies between those items, not to mention a bunch of special cases. In particular, I want to build in the possibility of a robust carbon cycle for a more-or-less-Earthlike world. The hypothesis is that the climate of Earth, or any similar planet with large oceans and life, will tend to self-correct over long periods. Carbon dioxide, in particular, will move into or out of the atmosphere in such a way as to keep the world in the proper temperature range for plentiful liquid water. That suggests a feedback loop that may require some special logic in the world-design sequence.
So I’ve been doing some storyboarding (kind of like what’s going on in this post from September) and roughing out the proper sequence of steps. I think I may end up with six or seven more major steps in the sequence. Seven would make a nice round thirty steps for the complete sequence, but if I end up with a weird prime number or something I suppose I’ll have to live with that.
In any case, I hope to break through the logic here and start posting the last chunk of the design sequence later this month. The third major piece of the sequence may be ready for PDF and posting to the Architect of Worlds page before Christmas.
That doesn’t mean Architect of Worlds, the book, will be ready. There’s a lot more I want to write before I’m ready to think about a publishable draft. How to plan an interstellar setting, how to work with real-world astronomical data, how to build star maps, that kind of thing. Still, I could see a first edition of the book finally making its appearance – most likely on DriveThruRPG.com – sometime next year.
The Sharrukin’s Worlds page has been eliminated. All new articles will most likely be filed under Free Articles and Fiction for the time being.
The Pages widget has been eliminated from the sidebar, but you should be able to access the major sections of the site from the menu bar at the top. I’m not sure anyone was using the widget anyway.
This process may have broken a link or two, but you should be able to reacquire without too much trouble. Hopefully, this should make navigation a bit easier in the future.
I think I may have finally gotten myself unblocked with respect to one of my long-term creative projects. The project in question is the Human Destiny setting.
The premise is that sometime in the middle of the 21st century, an interstellar civilization arrives in the Sol system and (without much effort) conquers humanity. It’s a strangely benign sort of conquest, though. The aliens don’t have any interest in us as slaves, nor are they motivated by a desire to take the solar system’s natural resources for their own benefit. Their goals seem mostly to involve . . . nannying us. Their laws are fairly strict, backed up by almost-universal surveillance, but enforcement seems to be non-violent, completely incorruptible, and even-handed. Meanwhile, all of us are provided a standard of living better than ever before, without anyone being required to work for any of it.
Naturally, a lot of humans resent all this mightily, but there seems to be nothing that can be done about it. The longer-term question is why all this has happened. What motivates the aliens?
I’ve written and published a couple of stories in this setting: “Pilgrimage” and “Guanahani.” I have two or three more stories in my development pile too. I’m fairly sure there’s a robust series, maybe even a few novels, in there. Yet, even after years of cogitation, I’ve never been able to get the idea to launch.
The main problem is that the setting does away with a lot of human agency just by its premise. Great, the aliens have come along and solved a lot of our problems, including many of the ones driven by human conflict and misbehavior. There are certainly stories left to be told, but a lot of the writer’s tools for plot and character development are set aside already.
It’s probably telling that almost all the stories I’ve written in this setting so far involve breakdowns of the alien surveillance apparatus. It’s kind of like Star Trek‘s transporters – they’re so useful for short-circuiting plots that a writer often has to justify taking them off-line before a story can happen.
There’s also the aliens’ motivation. They’re here because they want us to survive and evolve into the kind of species that actually can play a role on the galactic stage. That means human psychology needs to change. We need to learn to live with each other and tolerate the Other, we need to get better at understanding and preserving the big systems that keep us alive, we need to start thinking on much larger scales in both space and time.
So how do I write stories about that, in which the aliens demonstrate their motivations through conflict and plot rather than by simply telling the reader what’s up?
I was idly thinking about this the other day – a lot of my creative work happens in the back of my mind while I’m doing something else entirely. Then my mind made a connection with what I was doing with my hands and my forebrain at the time.
I was idly playing a game on my iPad, you see.
Terraforming Mars has been out for several years as a tabletop game, and now has a pretty good adaptation as a mobile app as well. It’s one of those wonderfully thematic board games that does such a superb job of making a complex subject playable and interesting to the layman.
Terraforming Mars assumes an era of exploration and colonization throughout the solar system, starting either late in this century or sometime in the next. The centerpiece of that era is a generations-long project to, as it says on the tin, terraform Mars – transform that planet into an at least marginally habitable world, where human beings can live freely with little or no life-support equipment.
Well. Suddenly I could see a lot of possible context for the Human Destiny setting, Suppose the aliens, aside from simply providing a decent quality of life for most humans, also opened the door for this kind of expansion into the solar system? If humans could settle on Mars, cooperate with each other in a project that might not pay off for many human lifetimes, wouldn’t that be an opportunity for some of us to demonstrate the citizen-of-the-galaxy mindset the aliens are looking for?
Right away, my brain started working on ways to get my character Aminata Ndoye – the protagonist of “Pilgrimage” and a few of the not-yet-published stories – involved in Martian terraforming and solar-system expansion. That in turn gave me a whole raft of new ideas about the Human Destiny setting as a whole.
All of which is to say that I might be turning back to that project, finally. My creative plate is rather full at the moment, between working on my Krava stories, and Architect of Worlds, and wanting to flesh out the EIDOLON game system a bit more. Still, as 2020 winds down I think I might be able to revisit the Human Destiny setting, rework the core documentation for that, and start making some of that information available. Readers of this blog, and my patrons over on Patreon, can expect to see some results from that over the next couple of months.
Architect of Worlds – Step Twenty-Three: Determine Atmospheric Mass and Pressure
In this step, we determine the atmospheric mass of the world under development. The atmospheric mass is measured relative to that of Earth – a world with surface gravity of exactly 1, and atmospheric pressure of exactly 1 “atmosphere” at the surface, will have an atmospheric mass of 1.
Some worlds will have a Trace atmosphere – enough to provide climate and weather effects on the world’s surface, but not enough to support any form of complex life. Still other worlds will have no atmosphere at all (or at least no atmosphere that can be detected without sensitive instruments). In both of these cases, the atmospheric mass will effectively be zero.
Atmospheric mass depends on a large number of factors: the world’s blackbody temperature and M-number (determined in Step Nineteen), its prevalence of water (determined in Step Twenty), whether it has undergone a runaway greenhouse event (also determined in Step Twenty), the degree of ongoing vulcanism (determined in Step Twenty-One), and the presence and strength of a magnetic field (determined in Step Twenty-Two).
Once a world’s atmospheric mass has been fixed, the pressure of the atmosphere at the surface (sea level or some other convenient “datum”) can also be determined.
Procedure
Begin by building a list of the likely major components of the world’s atmosphere. Refer to the following table, which lists a number of volatile compounds which might make up a large and stable portion of an atmosphere.
Atmospheric Components Table
Possible Major Component
Maximum M-Number
Minimum Blackbody Temperature
Molecular Hydrogen (H2)
2
20 K
Helium (He)
4
5 K
Molecular Nitrogen (N2)
28
80 K
Carbon Dioxide (CO2)
44
195 K
For each item on the Atmospheric Components Table, check to see whether the world under development has an M-number that is no higher than the one given in the table, and a blackbody temperature that is no lower than the one given in the table. If the M-number is too high, that potential component of the atmosphere will undergo thermal escape. If the blackbody temperature is too low, that component will tend to “freeze out” and form liquid or solid layers on the surface. Either way, that volatile will not be available to make up a substantial atmosphere.
Make a list of the atmospheric components that meet both conditions, and then refer to the following three cases.
First Case
This case holds if one or more of molecular hydrogen, helium, or molecular nitrogen meet both conditions from the table.
In this case, roll 3d6 and modify the result as follows:
+6 if the world has Massive prevalence of water
+6 if the world has undergone a runaway greenhouse event
+6 if the world has a Molten Lithosphere
+4 if the world has a Soft Lithosphere
+2 if the world has an Early Plate Lithosphere
-2 if the world has an Ancient Plate Lithosphere
-4 if the world has a Solid Lithosphere
-2 if the world has a Moderate Magnetic Field
-4 if the world has a Weak Magnetic Field
-6 if the world has no Magnetic Field
If the modified dice roll is 0 or less, then the world will have a Trace atmosphere, with an atmospheric mass of zero. Otherwise, multiply the modified dice roll by:
10 if the world has undergone a runaway greenhouse event
1 if the world has blackbody temperature less than 125 K and Massive prevalence of water
0.1 otherwise
The final result is the world’s atmospheric mass. Feel free to adjust this result by up to half of the multiplier.
Second Case
This case holds if the first case does not, but carbon dioxide meets both conditions from the table.
In this case, the world will automatically have a Trace atmosphere, with an atmospheric mass of zero.
Third Case
This case holds if neither the first case nor the second case is in effect (that is, none of the volatiles listed on the table meet both conditions).
In this case, the world will automatically have no significant atmosphere, and an atmospheric mass of zero.
Surface Atmospheric Pressure
To determine the atmospheric pressure at a world’s surface, multiply the atmospheric mass by its surface gravity.
Examples
Arcadia IV has blackbody temperature of 281 K, an M-number of 5, Extensive water with no runaway greenhouse, a Mature Plate Lithosphere, and a Strong Magnetic Field. Major components of the atmosphere will include both molecular nitrogen and carbon dioxide, so the planet falls squarely into the first case. Alice rolls an unmodified 3d6 and gets a result of 9, so Arcadia IV has an atmospheric mass of 0.9. Since the planet has surface gravity of 1.05, the atmospheric pressure at sea level is abut 0.95, very comparable to that of Earth.
Arcadia V has a blackbody temperature of 226 K, an M-number of 6, Moderate water with no runaway greenhouse, a Mature Plate Lithosphere, and no magnetic field. Major components of the atmosphere will include molecular nitrogen and carbon dioxide, so this planet also falls into the first case. Alice rolls 3d6-6 (modified due to the lack of a magnetic field) for a result of 7, so Arcadia V has an atmospheric mass of 0.7. The planet has surface gravity of 0.82, so atmospheric pressure at the surface is about 0.57.
A quick note to assure everyone that I’m still alive. I’ve been working on a lot of things this week, with the result that none of them have been pushed through to completion. Hopefully this weekend will help change that.
About finished with the next bit of Architect of Worlds, which will start establishing a designed world’s atmosphere and climate.
Still working on reviews of the second and third books in Gordon Doherty’s Empires of Bronze series, which will bring me to my goal for this first month of reviewing other people’s self-published books.
Picking out another piece of short fiction, to post here and send as a free reward for my patrons.
Also working on promotion for The Curse of Steel, and pushing forward with the first draft of The Sunlit Lands, both of which are important but aren’t likely to be visible here. Watch that progress bar, though!
Look for some results from that list over the next few days, I think.
Architect of Worlds – Step Twenty-Two: Determine Magnetic Field
In this step, we will estimate whether the world under development has a significant magnetic field.
The possible cases for a world’s magnetic field will be sorted into four categories: None, Weak, Moderate, and Strong, defined as follows.
None: The world has no detectable magnetic field and is completely unprotected from the stellar wind. Examples: Venus, Earth’s moon, Mars, most of the gas giant planets’ major satellites.
Weak: The world has a detectable magnetic field (about 1% as strong as Earth’s), but it offers no significant protection from the stellar wind. Examples: Mercury or Ganymede.
Moderate: The world’s magnetic field is strong enough to offer limited protection against the stellar wind (about 10% as strong as Earth’s). Examples: None in our planetary system.
Strong: The world’s magnetic field is at least comparable to that of Earth, sufficient to provide adequate protection against the stellar wind. Examples: Earth, the gas giant planets.
A world’s magnetic field seems to depend on several items:
The world needs to have a hot, liquid outer core of significant mass, composed largely of iron
There must be convection taking place in that iron outer core, causing rising and falling currents
The world must rotate on its axis
If all three of these conditions hold, the iron outer core forms a dynamo which creates a significant magnetic field. This, in turn, helps protect the world’s atmosphere from being stripped away by stellar wind, and also protects the surface of the world from some harmful radiation. In our own planetary system, only Earth and the gas giant planets have strong magnetic fields.
Note that the third condition – that the world must rotate on its axis – is almost universal. Even a tide-locked world still rotates on its axis, and physical modeling seems to indicate that even slow rotation is enough to support a working dynamo. The existence of strong convective heat transfer through a world’s outer core seems to be the critical factor.
Procedure
To determine the strength of a world’s magnetic field at random, roll 3d6 modified as follows:
+4 if the world has a Soft Lithosphere
+8 if the world has Early Plate Lithosphere or Ancient Plate Lithosphere and also has Mobile Plate Tectonics
+12 if the world has Mature Plate Lithosphere and also has Mobile Plate Tectonics
Refer to the Magnetic Field Table entry for the modified roll.
Magnetic Field Table
Modified Roll (3d6)
Magnetic Field
14 or less
None
15-17
Weak
18-19
Moderate
20 or greater
Strong
Examples
Arcadia IV has a Mature Plate Lithosphere and Mobile Plate Tectonics, so Alice rolls 3d6+12 and gets a result of 25. Arcadia IV has a Strong Magnetic Field.
Arcadia V has a Mature Plate Lithosphere but has Fixed Plate Tectonics. Alice rolls an unmodified 3d6 and gets a result of 13. Arcadia V has no significant magnetic field.
Well, The Curse of Steel has been on the market for about a week now. Sales have not been overwhelming, but I didn’t expect them to be. In any case, the book has already earned me more in royalties than my last two ventures into self-publishing put together. This is a slow business, which doesn’t reward you for obsessively checking your KDP reports.
(Have I been obsessively checking my KDP reports? Yes, yes I have.)
So, on to next steps.
I’ve started work on the first draft of the next novel in the series, The Sunlit Lands. Progress on that can be tracked in the sidebar.
Meanwhile, I’ve been working on promotion for The Curse of Steel. One thing I’ve become aware of is that there’s a whole ecology of reviewers for new books, and especially for self-published books. New books that don’t have many professional or customer reviews don’t do as well, but as you might expect there are always more new books coming out than there are available reviewers.
After thinking about that problem for a while, I’ve decided to add a new thread to this blog: reviews of new self-published fiction.
I’m going to try to have at least one substantive review of an indie novel or series per month. Those reviews will be posted as blog entries here, and if the book(s) being reviewed are being published on Amazon I’ll cross-post the reviews there too. Look for the first of these by the end of October – I’ve already found a very promising novel series that will almost certainly get a review.
This is something of a departure for me; this blog has never done many reviews in the past. It will involve some formal work over the next few days as I set things up. I’ll have to develop and post a review policy, and I’ll also be advertising this blog on some of the review-clearinghouse sites to attract more attention to the project.
As another point, I’ve just taken some steps to (hopefully) make this site a little easier to navigate. You’ll notice the white top-bar now provides several menu options. These links will take you to some of the most important (or popular) pages on the site, notably the Architect of Worlds landing page. I’ll be expanding that menu a bit over the next few days, possibly converting a couple of the items into drop-downs to further improve navigation. There may be some tweaks and additions to some of the pages as well. Feedback is welcome as to ways to improve all of this functionality.
Architect of Worlds – Step Twenty-One: Geophysical Parameters
Before we get started with this step in the design sequence, be aware that the modeling here is even more pragmatic and “rule-of-thumb” than usual. I think the following material will work properly, but it’s going to need some rigorous testing and tweaking before I’m satisfied with it.
In this step, we will determine some of the geological history of the world under development. In particular, we will estimate the world’s internal heat budget, characterize the presence and degree of active plate tectonics, and estimate the level of vulcanism.
A world’s internal heat will normally derive from three different sources:
The primordial heat of the world’s formation
Radiogenic heat derived from the decay of radioactive isotopes
Tidal heat generated by friction due to any tidal forces acting on the world
The structure and behavior of the world’s lithosphere will be strongly determined by the amount of heat remaining in the world’s deep interior. The hotter the world’s mantle and core, the more likely it is that heat will escape to and through the world’s surface, softening or melting surface rocks and possibly giving rise to volcanic eruptions.
Procedure
Primordial and Radiogenic Heat Budget
Begin by estimating the primordial and radiogenic heat budget of the world under development.
Evaluate the following quantity for all worlds:
Here, K is the density of the world compared to Earth, R is the world’s radius in kilometers, M is the metallicity of the star system (as determined in Step Five), and A is the age of the star system in billions of years. HP is a rough measure of the total amount of primordial heat and radiogenic heat a world possesses, on a logarithmic scale. On this scale, Earth had an HP value of about 90 immediately after its formation (and has an HP value of about 54 today).
Tidal Heat Budget
Not all worlds will have a significant budget of internal heat due to tidal friction. Or each world under development, check to see whether the world falls into any of the following two cases. If so, compute the quantity HT according to the formula given.
First Case: Major Satellites of Gas Giants
A major satellite of a gas giant planet only (not a Leftover Oligarch, Terrestrial Planet, or Failed Core) will experience significant tidal heating if and only if:
There is at least one other major moon in the next outward orbit from the gas giant, as established in Step Fourteen, the first case, and
That “next outward” major moon is in a stable resonance with the moon being developed (that is, the ratio of their two orbital radii was derived from the Stable Resonant Orbit Spacing Table in Step Eleven).
In this case, the resonance between the two orbital periods will tend to maintain a small degree of eccentricity in the first moon’s orbit. This in turn will cause tidal forces imposed by the gas giant to increase and decrease slightly during the moon’s orbital period, causing the moon’s body to “flex” and create friction. In our own planetary system, two of the satellites of Jupiter fall into this case (Io and Europa).
If a moon falls into this case, evaluate the following:
Here, M is the mass of the gas giant in Earth-masses, D is the moon’s radius in kilometers, and R is the moon’s orbital radius in kilometers. HT is a rough estimate of the moon’s tidal heat budget, on the same logarithmic scale as HP.
Second Case: Spin-Resonant Planets Without Major Satellites
A Leftover Oligarch, Terrestrial Planet, or Failed Core which has no major satellite may experience significant tidal heating due to its primary star, if and only if the planet is in a spin-orbit resonance with its primary star, as determined in Step Sixteen, and at least one of the two following cases is correct:
The spin-orbit resonance is not 1:1 (that is, the planet is not tide-locked to its primary star), or
Both of the following are true:
There is at least one other planet in the next outward orbit from the primary star, as established in Step Eleven, and
That “next outward” planet is in a stable resonance with the planet being developed (that is, the ratio of their two orbital radii was derived from the Stable Resonant Orbit Spacing Table).
In either case, tidal forces imposed by the primary star will cause the planet’s body to flex slightly during its orbital period, giving rise to internal friction and heat. In practice, the effect is likely to be minimal unless the planet orbits very close to its primary star.
If a planet falls into this case, evaluate the following:
Here, M is the mass of the primary star in solar masses, D is the planet’s radius in kilometers, and R is the planet’s orbital radius in AU. HT is a rough estimate of the planet’s tidal heat budget, on the same logarithmic scale as HP.
Once you have computed HP and (possibly) HT, make a note of the greater of the two– that is, the heat budget associated with the source that is currently providing more internal heat for the world – for use in the rest of this step.
Status of Lithosphere
The lithosphere of a world is the top layer of its rocky structure. A world’s lithosphere usually begins as a global sea of magma, but it will soon cool, forming a solid crust that provides a (more or less) stable surface. Over time, as the world cools, the crust will tend to become thicker and more rigid, eventually forming a single immobile plate that covers the entire sphere.
Note that on a world with Massive prevalence of water, the lithosphere is effectively inaccessible, submerged beneath deep ice sheets or liquid-water oceans. In this case, the actual surface of the world will be atop the water layers (the hydrosphere). Determine the status of the lithosphere in any case since it will still affect several other properties of the world.
The possible cases will be sorted into six categories: Molten, Soft, Early Plate, Mature Plate, Ancient Plate, and Solid. These categories are defined as follows.
Molten Lithosphere: Large portions of the world’s lithosphere are still covered by magma oceans. A thin solid crust may form in specific regions. Active volcanoes are extremely common and may appear anywhere on the lithosphere. Examples: Earth in the Hadean Eon.
Soft Lithosphere: A solid lithosphere has formed, and no magma oceans remain. However, the lithosphere is not strong enough to resist the upwelling of magma from the world’s mantle, so active volcanoes remain very common and continue to appear anywhere on the lithosphere. Examples: Earth in the early Archean Eon.
Early Plate Lithosphere: The lithosphere is becoming strong enough to resist the upwelling of magma from the mantle. The crust is organizing into solid plates. Volcanoes remain common, but (depending on the presence of active plate tectonics) may be limited to certain locations. Examples: Earth in the later Archean Eon.
Mature Plate Lithosphere: The organization of the crust into solid plates is complete, with most or all of the crust now integrated into the system. Some of the crustal plates are now thicker and more durable. Volcanoes are less common. Examples: Earth today.
Ancient Plate Lithosphere: The lithosphere is becoming thick and rigid, and the system of crustal plates is becoming stagnant. Vulcanism is increasingly rare. Examples: Earth billions of years from now, Mars today.
Solid Lithosphere: The lithosphere is solid and completely stagnant. Vulcanism is vanishingly rare or extinct. Examples: Earth’s moon.
To determine the current status of a world’s lithosphere, roll 3d6 and add HP or HT, whichever is greater. Then refer to the Lithosphere Table.
Lithosphere Table
Modified Roll (3d6)
Lithosphere Status
96 or higher
Molten Lithosphere
88-95
Soft Lithosphere
79-87
Early Plate Lithosphere
45-79
Mature Plate Lithosphere
31-44
Ancient Plate Lithosphere
30 or less
Solid Lithosphere
Plate Tectonics
Even if a world’s crust is organized into solid plates, those plates may or may not be able to move and interact in an active system of plate tectonics. In our own planetary system, several worlds show some sign of plate tectonics. However, only on Earth is the entire crust arranged into a clear set of plates that move across the mantle and actively recycle crust material. The decisive factor seems to be Earth’s extensive prevalence of water, which permeates the crustal rocks and reduces friction among the tectonic plates.
Determine the status of the world’s plate tectonics only if its lithosphere is in an Early Plate, Mature Plate, or Ancient Plate status as determined above.
The possible cases will be sorted into two categories: Mobile Plate Tectonics and Fixed Plate Tectonics, defined as follows.
Mobile Plate Tectonics: The crust’s tectonic plates are able to move freely past or against one another. As tectonic plates collide, some of them experience subduction, moving down into the mantle and recycling the crustal material. Orogeny, or the formation of mountain ranges, takes place in such areas as well. Volcanic activity is likely to take place at plate boundaries. Volcanoes may also appear in plate interiors, at the top of magma plumes rising from the deep mantle. Such shield volcanoes will tend to form arcs or chains, as the tectonic plate moves across the top of the plume.
Fixed Plate Tectonics: The crust’s tectonic plates are unable to move freely. Little or no subduction takes place to recycle crustal material. Orogeny is rare. As with Mobile Plate Tectonics, volcanoes are likely to appear at plate boundaries. Shield volcanoes are also possible, but since the tectonic plates are nearly immobile, such volcanoes can grow very large over time.
In general, a world is likely to have Mobile Plate Tectonics if it is younger (and therefore still has a hot mantle and core) and has plenty of surface water to reduce friction among the plates. To determine the status of a world’s plate tectonics at random, roll 3d6 and modify the result as follows:
+6 if the world has Extensive or Massive prevalence of water
-6 if the world has Minimal or Trace prevalence of water
+2 if the world has an Early Plate Lithosphere
-2 if the world has an Ancient Plate Lithosphere
A world will have Mobile Plate Tectonics on a modified roll of 11 or greater, and Fixed Plate Tectonics otherwise.
Special Case: Episodic Resurfacing
If a world has an Early Plate or Mature Plate Lithosphere, and has Fixed Plate Tectonics, then vulcanism will follow an unusual pattern of episodic resurfacing.
In this case, the lithosphere is too strong to permit magma to reach the surface under normal conditions. Since any tectonic plates are fixed in place, subduction and orogeny are very rare. Active volcanoes are also uncommon. However, heat built up in the mantle periodically breaks through, causing massive volcanic outbursts that “resurface” large portions of the lithosphere before the situation restabilizes.
For an Early Plate Lithosphere, these resurfacing events will take place millions of years apart. For a Mature Plate Lithosphere, resurfacing becomes much less frequent, tens or even hundreds of millions of years apart. In our own planetary system, Venus is an example of this case.
Examples
Both Arcadia IV and Arcadia V are planets without major satellites, and both of them are at a significant distance from the primary star, so Alice assumes that tidal heating will be insignificant for both of them. She evaluates HP for both. The star system is 5.6 billion years old and has metallicity of 0.63.
Arcadia IV has density of 1.04 and radius of 6450 kilometers, and so has HP of 41 (rounded to the nearest integer). With a 3d6 roll of 9, the total is 50. Arcadia IV has a Mature Plate Lithosphere.
Arcadia V has density of 0.92 and radius of 5670 kilometers, and so has HP of 34 (rounded to the nearest integer). With a 3d6 roll of 13, the total is 47. Arcadia V also has a Mature Plate Lithosphere. Notice that both of these planets have total scores fairly low in the range for a Mature Plate result, indicating that they have rather “old” geology and may be transitioning to an Ancient Plate configuration.
Arcadia IV has Extensive water, so Alice rolls 3d6+6 for a result of 15. Arcadia IV has Mobile Plate Tectonics, resembling Earth in this respect.
Arcadia V only has Moderate water, so Alice makes an unmodified roll of 3d6 for a result of 7. Arcadia V has Fixed Plate Tectonics and exhibits episodic resurfacing on a timescale of tens or hundreds of millions of years.
I’m still working on the next step in the Architect of Worlds design sequence.
This one is proving a bit thornier than usual, because I’m trying to model a very complex system. This step is doing a lot of the heavy lifting to describe the geology of a world. I need something that can handle Earth’s complex plate-tectonics geology, and the stagnant-plate geologies of Venus and Mars, and the mega-vulcanism of Io, and putative super-Earths, and can also handle long stretches of geologic time, and and and. Tall order . . . although I think I’m converging on something that will work well enough. A few more days of work on that, most likely, and then the next block of draft text will appear here.
Meanwhile, as of today the editor I hired to review the draft of The Curse of Steel has finished his work, and his assessment was bothuseful and very positive. The big takeaway here is that he’s confirmed my belief that the current draft does not need any more major surgery. I estimate about two more weeks of work, to finish the glossary, go through the draft one last time to pick a few more nits out of the prose, assemble the e-book files, and publish.
The Curse of Steel will almost certainly be available on Kindle Direct by the middle of October. At the point of release, anyone who’s signed up as my patron at the $2 level or above will receive a free copy of the e-book, and anyone who’s signed up at the $5 level or above will be mentioned in the Acknowledgements section of the book.
After which, I plan to spend about three days in unashamed celebration, and then it will be time to get to work on the next book in the series: The Sunlit Lands.
Architect of Worlds – Step Twenty: Determine Prevalence of Water
Water is one of the most common substances in the universe. Its special properties will lead it to have a profound effect on the surface conditions of any world, from its initial geological development, to its eventual climate, and finally to the evolution of life. Some worlds may never have much water, others will tend to lose whatever water they begin with, and still others will retain massive amounts of water throughout their lives.
In this step, we will estimate how much water can be found on a given world. The possible cases will be sorted into five categories: Trace, Minimal, Moderate, Extensive, and Massive. These categories are defined as follows.
Trace: No liquid water or water ice remains on the vast majority of the surface. If there is a substantial atmosphere, it may carry traces of water vapor. Small pockets of water ice may remain on the surface, in permanently shadowed craters or valleys, or on the night face of a world tide-locked to its primary star. Small deposits of water may be locked in hydrated minerals deep below the surface. Examples: Mercury, Venus, Earth’s moon, or Io.
Minimal: Liquid water is vanishingly rare on the surface, but large deposits of water ice may exist in the form of polar caps, in sheltered craters or valleys, or on the night face of a tide-locked world. Substantial aquifers or ice deposits may exist close beneath the surface. Hydrated minerals can be found in the world’s interior. Examples: Mars.
Moderate: A substantial portion of the world’s surface, but not a majority, is covered by some combination of liquid-water seas and water ice, depending on local temperature. The liquid-water oceans or ice deposits are up to a few kilometers in depth. Far away from the oceans or ice deposits, water becomes vanishingly rare. Hydrated minerals are common in the world’s interior. Examples: Mars a few billion years ago.
Extensive: Most of the world’s surface is covered by some combination of liquid-water oceans and water ice, up to several kilometers in depth. Water is common in most areas of the surface, even away from the oceans or ice deposits. Hydrated minerals are plentiful far into the world’s interior. Examples: Earth, Venus a few billion years ago.
Massive: The entire surface is covered by some combination of liquid-water oceans and water ice, up to hundreds of kilometers deep. Deeper layers of this world-ocean may be composed of higher-level crystalline forms of water (Ice II and up). Hydrated minerals are plentiful far into the world’s interior. Examples: Europa, Ganymede, Callisto, Titan, some “super-Earth” exoplanets.
The amount of water available on a given world will depend upon its M-number (Step Nineteen), its blackbody temperature (Step Nineteen), its location with respect to the protoplanetary disk (Step Nine), and (in some cases) the arrangement of any gas giant planets elsewhere in the planetary system (Steps Ten and Eleven).
Procedure
Begin by noting which of the following three cases the world being developed falls under, based on its M-number.
First Case: M-number is 2 or less
In this case, the world’s prevalence of water is automatically Massive.
Second Case: M-number is between 3 and 28
In this case, determine whether the world is outside or inside the protoplanetary nebula’s snow line, as determined in Step Nine. If the world’s orbital radius (or that of its planet, in the case of a major satellite) is exactly on the snow line, assume that it is outside.
If the world in this case is outside the snow line, then its prevalence of water is automatically Massive.
If the world in this case is inside the snow line, then roll 3d6, modified as follows:
Subtract the world’s M-number.
Add +6 if there exists a dominant gas giant in the planetary system, it experienced a Grand Tack event, and it is currently outside the protoplanetary nebula’s snow line.
Add +3 if any gas giants in the planetary system are currently outside the protoplanetary nebula’s slow-accretion line.
Take the modified 3d6 roll and refer to the Initial Water Prevalence table:
Initial Water Prevalence Table
Modified Roll (3d6)
Prevalence
-5 or less
Trace
-4 to 3
Minimal
4 to 11
Moderate
12 to 19
Extensive
20 or higher
Massive
If the result on the table is Moderate or higher, and the world’s blackbody temperature is 300 K or greater, then the presence of water vapor in the world’s atmosphere has given rise to a runaway greenhouse event. Make a note of this event for later steps in the design sequence and reduce the prevalence of water to Trace.
Otherwise (the world’s blackbody temperature is less than 300 K) the prevalence of water is as indicated on the table.
Third Case: M-number is 29 or greater
In this case, determine whether any of the three following cases is true:
The world’s blackbody temperature is 125 K or greater.
The world is the major satellite of a Large gas giant, and its orbital radius is no more than 8 times the radius of the gas giant.
The world is the major satellite of a Very Large gas giant, and its orbital radius is no more than 12 times the radius of the gas giant.
If any of these three cases are true, then the world’s prevalence of water is Trace. Otherwise, its prevalence of water is Massive.
Examples
Both Arcadia IV and Arcadia V fall into the second case. The Arcadia system has a dominant gas giant, which underwent a Grand Tack and ended up outside the snow line. The outermost gas giant (at 9.50 AU) is not outside the system’s slow-accretion line (at 14.0 AU). For both planets, therefore, she will roll 3d6, minus the planet’s M-number, plus 6. Her rolls are 13 for Arcadia IV and 10 for Arcadia V, so Arcadia IV has Extensive water while Arcadia V has only Moderate water.
