Showing posts with label OTHER. Show all posts
Showing posts with label OTHER. Show all posts

27 June, 2021

OTHER CONCEPTS | SPACESHIP DESIGN & SPACE WARFARE | PART 3 - A PRACTICAL APPROACH

OUT TO THE BATH TUB FIELD TESTING

It's been one year since the last time we talked about Space Warfare here on Hard Sci-Fi.

Let's recap what happened of the course of the previous two posts:

PART 1 - MOST SHIPS IN SCIENCE FICTION MAKE NO SENSE

PART 2 - WHY COMMON COUNTER ARGUMENTS MAKE EVEN LESS SENSE, EVEN IN-UNIVERSE

In Part 2, I left the post on a cliffhanger about disruptive camouflages - highlight to a more sci-fi approach to Dazzle camouflage.

Amongst other types of camouflage, I had also included chemicals that disguise the ship as another object like a comet, and reflective panels that can be tweaked in order the flash light-rays into or away from the enemy (also known as mirrors).

This time, I'm willing to test some of those approaches, in a simple observation test, simulated in a 3D modeling software.

So, meet our test ships:

NSC 042 - SCITALIS

This design is inspired by the myriad of accurate and cool-looking spaceships created by MarkPoe

The Nuclear-Powered Support Cruiser 's role is to ensure the security of high-value targets by supporting the escort effort with massive suppressive firepower, hence why it has a ridge along it's hull, from where 75x 80mm Fast-Pace Artillery guns (FPA), and 6x 300kg Kinetic-Kill Disperser weapons (KKD) - per side.

So basically each broadside holds 75x machine guns and 6x shotguns.

Why this ship carries relatively small machine guns and a couple of shotguns are because of two reasons.

1. The sharp acute holes of the bullets are meant to be very hard to find and repair compared to the amount of damage to O2, electronics and heatsink systems on the enemy - firing along a path line grants more potential hits and suppressive fire. 


2. Shotguns are crude in space, and mainly if the enemy is accompanied - granting sector clearance nearby because of the nearly invisible but deadly pellets (and there is 300kg of them per shot), such weapons can also intercept HTK vehicles and drones inbound, making very large projectiles or missiles not so useful from certain angles.


The name Scitalis, refers to the medieval beast that sports beautiful shiny marks - pretty straight forward.

The four plates are shielding the fuel tanks against debris and projectiles, the two skirts are sections of parabolic surfaces, so incoming kinetic projectiles are ricocheted away from the ship's hull, the internal reflection angles were carefully chosen so any shots fired against them wouldn't redirect the bullets to sensible parts of the beaming and engines.


The standard combat instance for this ship would then be facing the enemy at 3/4, with minimal exposition of sensible parts and maximum weapon coverage (like the top-right window view).


11 June, 2021

OTHER CONCEPTS | FTL DEPICTION PART 2

 ...BUT THERE ARE NO SEAT-BELTS, SIR


In the last post, we talked about how we should accurately depict Faster-Than-Light travel.

Using doppler shifts and various >cough< plot devices >cough< methods of choice.

Now, this is also a guide on how to gauge the mean age of an interstellar civilization, by it's size - you will see how in a moment.

First, let's pose a problem.

Imagine how many stars there are in a 50ly radius, 100? 1k? 10k? Let's stick with 1k for now - let's say that 20% of those stars hold habitable planets we wanna settle, so 200 places to go, quite a schedule, isn't it?

So a bubble of 50ly has a volume of ~523.598,7ly³ (593,6 thousand cubic ly), or roughly 13,78ly in between stars with habitable planets (cube root of volume divided by amount).

If we plot a perfect route, that lines up every star in these roughly 13,78ly space, we get (200)*13,78 = 2756,47ly to travel.

Theoretically we could launch 200 missions at the same time, now, is it feasible? Not really, because of the sheer amount of personnel and resources to do so.

Let's say we launch a mission every 4 years, and that we take about 1 year to establish a decent outpost over there (being extremely optimist).

That gives us +1.000 years of work.


Now, the final touch is know at what speed are we traveling - let's calculate for 0,1c, then do the same for 1,0c and 10c.

(2756,47ly / 0,1c) + 1000yrs = 28.564,7yrs.


28,56kyr ago mankind had just invented pottery, who knows if we will even be around back on Earth in 28,6 thousand years?

That goes down to 3,75kyr for 1,0c - then 1,27kyr at 10c.

We see that - in very simple words - traveling at subluminal speeds sucks to an awful lot.

But when traveling at the speed of light and beyond, that time is only determined by how fast we can do stuff after getting there, once there is a point that travel is nearly instant to the destination, but people still do work at people-speed.

Now, settling all planets in a space with double the radius would take not double the time, but 8x the time (square-cube law), so even at the best of 1,27kyr at 10c, it would take ~10 thousand years to do so.

Again, it's a hell of a pain to go further and further from home even at superluminal speeds.


Things like this are the reason that - I, personally - don't believe we have been, and won't be for a long looong time, visited by any aliens. It's so unimaginably hard to do so that is just so improbable to happen, simple like that. If one wanna believe anyone has been ever able to build an empire that's 100ly in radius, well, they aren't even close to us because their radio-bubble would be at least 20kly across, and more realistically detectable in the whole galaxy by such timescales.

What I would use to explain UFOs? WHATEVER, whatever but aliens, extra-dimensional beings are 2nd in line, but I really doubt the shapes they present for a number of other reasons, leaving it blank for either a complete hoax or someone's experimental aircraft despite the denials.


TIME DILATION AND CAUSALITY ISSUES


The above equation works to figure the time dilation relative to one traveling at subluminal speeds - in other words - the time one left on Earth experiences (t'sec) during your travel time tsec.

For our first example at 0,1c, we expend over 27,56kyr traveling from our perspective, however on Earth it will be over ~27,7kyrs.

It gets worse if we wanted to go faster, at 0,95c that time for one on Earth becomes over 88,26kyr.

At 0,99962c, the perceived time would be of 1Myr.


If we want to go at superluminal speeds though, we must invert the sign to:


The above form tells you how much time has passed outside the ship while traveling at some multiple of lightspeed.

The problem is that any dilation for superluminal speeds is negative - that means if any traveler at 1,5c for 1 day, would arrive at their destination 1d19h (1,80 days) in the past relative to departure time.

That clearly violates causality, if one did such a trip to the outer Kuiper Belt and back to Earth they could interact with themselves and mess their own timeline which shouldn't be possible.

The same goes for instantaneous travel or communication.

Imagine that I sit down for a small lunch listening to the radio before flipping the switch on my spaceship, then, I travel to Saturn at 10c, and from Saturn I beam an INSTANTANEOUS message back about my experience.

The distance to Saturn in light-units is about 1h17min, so it would take me little over 7min42s to get there are 10c, relativity tells that I arrive at Saturn about 1h17min23s in the past relative to Earth's departure time...

Now, when I beam my instant message back to Earth, it will catch with my past self before the launch.

If I decide to go back 5min after or beam another message at 10c instead of instantaneous, the time dilation will cancel out plus the time it took between my arrival and the action - giving people on Earth the impression that me or the second message came back 5min after I left, even though for both of us it would have taken about 7,7 minutes.

so, yea - that's really big problem right there

THE 'PLANET OF THE APES' EFFECT


Another thing is that if you accept there is no way to travel faster than light without violating causality, then you cannot travel at THE speed of light as well, because not only it would require infinite energy to do so - but because it imposes infinite time dilation, ie, instantaneous travel, at the cost of also arriving by the End of Time.

Traveling very close to c, at 99,999...99% could be virtually instantaneous to the crew but cost thousands to billions of years for those "stationary".

Which by itself is an interesting plot, oh wait, Planet of the Apes (1968) did that already.

The point I'm trying to make bringing up causality is that one crew that travels at such a considerable portion of the speed of light or/and uses cryosleep is, by default - anachronistic in nature.

Society's logistical apparatus as we know can't survive in such an environment, not in practice.

Imagine you people of present day USA, traveling to Epsilon Eridani (10,5ly) to retrieve whatever amount of tons of unnobtainium, say at 0,5c, it would take you 5,25 years to do so, while 6 years go by on Earth, then 12 years later for your family on Earth (and 10,5yrs for you) you finally come back - except now half of the US now belongs to China and the New Malasyan Federation, in other words, your boss probably isn't around anymore and all that ore now belongs to the Chinese people. GREAT, ISN'T IT? :D

Now, the faster you travel, the greater the chance of some weird shit messing up with the world you knew before you left - you are essentially a Time-Traveler, and the only constant environment and people you will ever know from this point onwards are your ship and crew.


This stability may not be really a problem for short-term effects like one or two decades, but once things get to life-time lengths - things start to get really complicated with the logistics of it as I already said. Because of this, there is no real reason for like alien invasions to take place because they need water or some super valuable mineral, because when they return home their people will be long gone already.


5 QUASI-RULES FOR A NEAR-LIGHTSPEED TRAVELER

#1. The ship and crew are your only home and family now.

#2. What belongs in a system, stays on that system - in general it's just not worth bringing it to your homeplanet.

#3. Only departure from a system when you are absolutely sure you are done with business - there is no time for mistkaes.

#4. Every jump means you will find a new world, both geographically and culturally different, be cautious and comprehensive with the people of the future, you're the caveman there.

#5. Your words have absolutely more power than everyone else's depending on one's perspective, your experiences are always fresher than everyone else's and your knowledge and even equipment will have a high-value for various groups - be careful and have minimal interaction whenever possible.

#6. Your ship is a literal Relativistic Weapon, so NEVER under any sane circumstance aim your ship directly at any planet or moon. 

 


THE SILVERLINING FOR ALIEN OVERLORDS...

If from the perspective of enthusiasts and explorers, it really sucks to expend thousands of years away from home - for the ones with questionable morals and motives, it's the perfect tool for oppressive conduct.

WHAT? But you just said that traveling at such speeds and long distance sucks and how it totally disproves interstellar empires and aaaaaaaaaaaaa

- probably you right now

I'm not contradicting myself - in fact - the same principle still apply, to travel for such a big volume of space such as a 100ly radius bubble it would take over thousands of years - still, way less than for people "stationary" on those worlds.

Let's imagine that I want to secure my brand new stellar empire doesn't fall short - well, I prepare a set of highly trained personnel and commanders (maybe even myself) and create a society in space, constantly traveling between points at near lightspeed.

The planets I conquered will tend to deviate from the norm and that's a fact, look how's the US and Russia compared to how it was 50 years ago, but instead of me and my comrades die in 50 years time, I just come back having aged only 15,6 years after traveling at 95% lightspeed to put things back in line.

Like this, if such one leader or ideology would have crumbled after 50 years, it can now survive 3x as long because of this tiny detail.

Now boarding a society in an alien planet, giving them 10 years to surrender and actually coming back in 10 years (~3yrs for you) with an entire orbital bombardment armada becomes really practical.

The downside of this is that your society has now gone totally space faring, so no permanent surface settlements unless one wants and manages to abandon such weird way of life :b

... AND SPACE FLOOD-ARKS

Also if for some reason your species really need long storage of DNA and other sensible specimens because of a cataclysmic event such as Nuclear War, Gamma-Ray Burst, or Asteroid Impact - well the long-term effects those leave on the planet can be easily overlooked because you can feasibly fast-forward to centuries in the future when the environment has recovered back to normal. Of course, assuming you have already mastered near-lightspeed travel in the first place.


- M.O. Valent, 11/06/2021

04 June, 2021

OTHER | MOUNTAIN HEIGHTS

TO THE TOP OF THE WORLD

When worldbuilding we are lead to add a couple of big mountains on the map and just call it a day - but, how tall should they be? *cue music*

That's a rather complicated question, to put it on simple terms, it mostly depends on the compressive strength and density of the material used on the mountain, and planet gravity.

The amount of weight above the mountain base shouldn't exceed the compressive strength of the material, ie, stress - or else the entire thing will collapse back to stability.

Let's assume our mountain is made of granite, which have a density of ~3g/cm³, and a compressive strength of 200MPa.

Let's make our mountain a cone of base h and radius r - it's volume will be given by:


Since (1/3)*π approaches ~1 (1,03669), we can get rid of that part for simplicity sake, leaving us with r²h.

The weight of our mountain can then be calculated by multiplying it's density, planet gravity and volume altogether.


Now, our mountain is a cone, which means that it has a round base, to get how much force it exerts on the base, we need to know the base area, which is a circle of area = πr².

So the little count below should give us the stress exerted by our mountain.


Switching to solve for hmax, we get:


Solving for our granite mountain, we get just over 6,79~7,84km, within the density range of pure granite.

If something seems wrong to you, knowing that the Everest is 8,8km high, you're not alone - first of all, this model assumes uniform density, which let's be realist - don't really exist in most natural formations, because the Earth's crust exist in layers, which are twisted by geological processes over the eons.


Another very important factor people seem to glance over is the stable shape of our mountain, we can't just throw any r and h in our equation too.

For any material that's being piled, there's a certain angle base-to-top up to which the pile is stable - the Repose Angle - which is defined by the specific material's static friction and grain-size.


The repose angle of a pile is an important concept in Civil Engineering because it helps saving material and funds when building earthen structures, bases, and grain silos. The smaller the repose angle the better the flow properties of the material used - by opposition, the higher the repose angle the worse the flow properties, and thus, more rigid is our material.

Okay, knowing the angle of repose of our mountain helps us to better understand it's dimensions.

There are two ways to easily get to those values:

    1. Figure out a way to find the exact materials in question, mix them, and then pour over a plane to a determined height or base width, and take the measurements yourself.

    2. Take the data from someone that has gone through method 1.

On relatively small piles, we can assume dry grain size to be the most important factor, such as:


Although mountains are made of grains and crystallized material, it's much more cohesive than a pile of sand or muscovite clay.

Also, the grains within rock are compressed by their neighbors along the very vast majority of the rocky structure. So rather than considering grain size, we will be using static friction coefficients, and determine fault planes along which will form our mountain's slope - ie, an inclined plane problem.

Through a series of transformations, we get to this:


The angle (in degrees, not radians) at which a body/grain will roll downhill is equal to the inverse tangent of the static friction coefficient.

The problem here arises from the fact that it varies a lot from the materials used - you see, a piece of glass will slide more against concrete than a piece of rubber.

Concrete-to-Rock friction coefficients, depending whether it is wet or dry rock and what rock was tested varies from 0,50 to 0,70, with Concrete-to-Concrete friction having an average of 0,53.

With this in hand, our mountains can have slopes between 26,56º and  34,99º.


Now, we get to the though parts.

We know the angle of our slope, let's pick 32,47º, and determine that the base of our mountain is 16km wide, the crest of our mountain is at half that distance so 8km - to figure out the height, we just have to multiply the tangent of our angle by the base length (8km).

We get just about 5km, which, thrown into our stress equation, becomes 150MPa - which is little bellow our granite compressive strength limit, and so, just about okay.

I can't resist but to estimate things on Paart, so using the same constraints, this mountain could be 373m taller before having the same pressure at the base, implying a slope angle of 34,36º.

Calculating for a mountain that's just over the strength limit but with the apparent density of the Everest, we get about 9,5km tall, with a base width varying between 19,0 ~ 13,6km in radius depending on whether it's slope is less or more steep - compared to Everest's approximate 11,4km.

A simple image showing the proportions of the two mountains, the one on Paart has been temporarily named to Caelum (sky) mons.

(relative to immediate surrounding terrain, measured from Everest Camp I at 6km to summit gives 3,7km, following the steepness to sealevel takes that to 11,4km).

Of course, mountains aren't just giant rocky cones that elevate above plains of terrain, mountains like the Everest originate from mountain ranges full of convoluted systems of canyons sculpted by the drainage of snow over the ages.

surrounding terrain to Everest in the Himalayas

Be sure to give your world's top a couple of sister mountains that branch away into more and more along the entire mountain range.

Below a table of reference materials that you could use to make a mountain out of.

Theoretically, you could define the different layers of material in your planet's crust where the mountain forms, and then, calculate mountains within mountains for every material and thus determine what it's made of (relative to a cut at sealevel). But that's up to you now.


- M.O. Valent, 04/06/2021

20 January, 2021

A Detailed Approach on District 9's Prawn Language | Part 1 | The Script

MNU SPREADS LIES!

Unfortunately, the original blog that this title refers to has been taken down by Sony Pictures.


ANYWAY - this is actually a pretty sudden idea I had earlier this day (saturday 5) while in the shower - District 9 is what I consider the masterpiece of Neill Blomkamp's work as writer and film maker. It is out of the bat an outstandingly complex, bold and action and drama intense movie from start to finish. It has so much to offer that I'm sometimes afraid of what could come out with a possible sequel if it ever gets to happen - say it's like to wait for Half-Life 3.

District 9 is an 11yo sci-fi drama/action movie by now, and why does it still deserve a lot of attention from the public? - by that I mean, us sci-fi nerds... The Alien Language.

Keep in mind that most of the information and material used throughout this post is sourced from the movie itself, and not by interviews and obscure blogs - for the reasons bellow.

Like I said, District 9 is a decade old already, pretty much like No Man's Sky (which I plan to study the glyphs of), it had the time to build on a solid fanbase, at least for a while (seems like at most 4yrs after the movie came out), and it actually impresses me how little there is actually about how deep does the rabbit hole goes on it's language affairs - the alien language is a solid aspect of the movie, not just a background quirk of pure gibberish in an alien key-set like some movies and games do.


The Non-Human Glyphs

In the movie, the aliens have been around for 28 years, landing in South Africa by 1982, and so the humans had nearly 3 decades to learn the alien language and them to learn english - and both species seem to understand each other with reasonable if not great success - without needing one to actually speak english or the alien tongue, Han Solo style.

What does impress me a lot, of course, in the context of the movie it makes a lot of sense, in general that humans are stupid and racists, but is that the alien glyphs have been around for a long time, and still, people just label it as "gang marks" and stuff of the kind - it's never said on the movie, but it's rather probable that the name of the alien species, or at least, that specific group landed in Johannesburg is called Poleepkwa (Polip'qua? Pa-le'ep'kva????).


Back to my shower thoughts, I recall that by the time I had watched District 9 for the first time, I had become really interested by making and writing alien languages as well of designing cool visuals for tech in general, but I've never saw much more than an already well known key-bind of the Poleepkwa glyphs so far:

Notice that F, ', -, &, @, and / , are all the same glyph

Also, here is how Hard Sci Fi look like in Poleepkwan:


It's actually pretty tricky and hurtful to look at - a lot of people like to compare it as techno-version of Chinese or Japanese, I can see why - but it isn't as simple as that, however, like us humans do - we could suggest this is just a font choice for their tech inscriptions - pretty much, we are not looking at Sans type of script here, but more like a stylized version of those - what make things not that much easier to read.

Also, the keybinding is much of an over-simplification, to assume on the aliens would use exactly 26 symbols each for a letter of the english alphabet, there is just too much going on for the amount of information people assume it is giving. There isn't enough context for us to infer what is the exact meaning of each symbol yet.


Is there any extra material around?

Not really, every mention I could find to the Poleepkwa glyphs leads back to the keybind already shown, another fan-made font also based off that key can be found here. I also stumbled upon one particular person that worked on a small expansion of the glyphs from 2011 to 2012 - but it's a non-cannon porn fanfic. Another instance of fan-made work takes us back to a russian table of characters.

 

At first, I got pretty happy in finding this, after all, Russian has 33 characters, so we would have more glyphs to work with and even sounds.

So yep, not any useful extra material really.


Ok, what about what's in the movie then?

Yes, there are about 30 occasions any symbols are somewhat readable, in full view or significant throughout the movie, ie, not going through every blurry alien screen frame-by-frame.

The funny thing though, is that many of the symbols ARE NOT listed in the key given - and since it's been 11 years since the release, Sony Pictures has also taken down the original font download page - so, unless I happen to stumble onto someone that happens to still have that, we won't ever know if the image we have as a source includes ALL the symbols or if it's just the ones that match with english characters in the keyboard.

Some other symbols happen to appear inconsistently in pieces of tech/weapons and screens - unless you consider it in a very general way, it's just there for the visuals.

From now and on, I will use sketches for the symbols for simplicity - as of the original pictures are sort of blurry and unclear.


How much readable content there is?

First, the material I've used will be available at my Google Drive.

The exosuit/mech chase scene had given me some clues to how the language works - still, one would have to own a blu-ray or HD copy of the film and analyze the scene frame-by-frame to record each of the Poleepkwan glyphs - I'm not that person, at least for now, I have managed to get only two glyphs off that scene.

As we will see, the clue I've got links back to my original hypothesis that the glyphs are actually too complicated for a simple english-alphabet key.

Notice how this glyph has parts from both A/V and S. The other one sports parts of M in different order. Hinting and odds are that the Poleepkwan writing system works with glyphs made of smaller parts, kind of how Kanji and Hangul works - though, we would need to analyze a ton of other glyphs to know exactly which are separate parts and which are diacritics or floating elements of certain glyph parts.


My attempt to explain Poleepkwan Script

So here is the way I found to dissect and write Poleepkwan.

First, I tried grouping look-alike glyphs:

There is much probably other ways I overlooked when making this

 

And then I dissected the elements shown in the letter glyphs - there are about writing 37 elements, or just 20-ish to 30-ish elements if you consider rotations and repetitions to stack up.




I made small notes on each marking and questioned for a bit - there is also the problem of reading direction, which we see not many hints of whatsoever (for the individual glyph parts), every alien text is either a single glyph or bulk text. In scenes showing Christopher's computers in the hut, we see that at least, they read it top to bottom, left to right, when arranged in paragraphs (presumably, on how the text is generated on the screens).

In the hiatus time i took away from this post, plus investigation, I couldn't much progress in trying to read the script in any meaningfull way - we would need a couple of written words and their sounds to try make out a few of the sounds of this language.


Val, out...


- M.O. Valent, 13/12/2020 

- M.O. Valent, 20/01/2021 



16 September, 2020

OTHER | PLANET CLASSIFICATION GUIDE

PLANET CLASSIFICATION GUIDE

We've for long referred to planets by their types here in this blog, using words like Terran or Terrestrial (derived from the Latin for Earth, Terra), or Gas Giant / Jovian (as relating to Jupiter), and so on, some terms are analogous, others rely on the knowledge of the reader to catch on, wouldn't it be good to have table with known, or, theoretically possible planet types?

Fans of the Star Trek series may recall have heard a couple times mr.Spok read on a planet's stats after scanning, coming up with planet classes as M, when referring to Earth-like worlds.

There isn't much of a real life parameter to pinpoint planet types as of today, it may happen in the future though, what we have are some base models applied to our planets and known exoplanets.

When I started this blog, I presented to you a couple planet types, but they come in even more flavours than that.

I'll build a planet classification chart along this post, more of as a baseline for future references.

THE FOLLOWING TEXT REFERS TO HOW I WOULD CLASSIFY PLANETS ACCORDING TO WHAT I HAVE READ ABOUT THEORETICAL AND OBSERVED PLANET TYPES
COMPLEMENTARY GRAPHS ARE FOUND AT THE END OF THE POST 

When we first look at our solar system we tend to classify it in rocky planets and gaseous planets, which is pretty fine, but we need to get more detailed.
Composition can vary a lot even between the 'uniform' gas giants, as they can be made of several different compounds such as light and heavy volatiles.

We can already expand our classification from 2 boxes (rocky and gaseous) to a lot more if we include mean composition, mass, and density alone - some planet types are also characterized by their temperatutes, orbits, or atmospheric conditions.

Me ~ Earth Mass
Mj ~ Jupiter Mass

Re ~ Earth Radius
Rj ~Jupiter Radius

I will use a concatenation system of Class-Subclass-Type/Subtype, or for clarity, UPPERCASE-Number-lowercase.

Potentially habitable for complex-life and microorganisms only types depending on atmospheric conditions color-coded GREEN and RED,  respectively, with an uncertainty midterm being YELLOW.


Class S - Subterran
A planet which mass and radius are substantially inferior to that of Earth and Venus.
A Subterran planetary mass range from 0,001 Me to 0,5 Me, and depending on composition, are usually smaller than Earth.

Subclass 1 - Dwarf Planet
A body which is massive enough to molded in a round form by it's own gravity, but not enough to cleanse it's orbital vicinity, and it's also not gravitationally bound to a particularly larger body than itself (like a main planet).
The mass of a Dwarf Planet is less than 0,01 Me, but more than most common large asteroids. Commonly made of rock and ice and can form beyond a star's terrestrial accretion limit.
Such a body around 0,01 Me in mass - made of Lunar regolith, would have a diameter of 0,254 Re.
Type a - Plutine
A body that's roughly 70% rock and 30% water ice by mass, may contain a thin atmosphere of methane and nitrogen, and some ammonia, the body most likely formed and still orbits beyond the Frost line.

Such world with 0,01 Me would be 3.058km wide - or 0,24 Re.

Type b - Cererian
A body that's 60~70% rock and 30~40% water ice by mass, the main difference between a Selenes and Hygieans is that those form before the Frost line, likely to inhabit the system's asteroid belt, it's tenuous atmosphere is composed of water vapour outgassing and sublimation and likely extends as a cloud around the object rather than a layer near the surface - which is composed of a silicate, piroxene, and ice mixture, and presents heavy createring.

Type b - Selene
A dwarf planet that is almost entirely rock, covered by piroxene, silicates and basaltic rock, having little to no water ice, much probably the leftovers of protoplanet formation of the system.


Type d - Hygiean
A dwarf planet that is not nearly as spherical as the others, but it's not an asteroid too, having some significant assimetry of it's axis for some reason - too little mass, low density and high rotation, or had a chunk of itself tore apart during impact events, like Haumea and Hygiea.

Subclass 2 - Minor Planet
A planet which mass is greater than 0,01 Me and less than 0,1 Me, can be made of metals, silicates, and ices depending on specific composition, due to low mass - these planets aren't suitable for holding on a long lasting atmosphere.

Type a - Mercurian
A planet which mass is within the minor planet subclass, however, it's found in the inner part of it's star system, atmosphere is nearly or completely absent and one remarkably characteristic is the extreme temperature difference between the night and day side of the planet.

A planet like Mercury would have a density similar to that of Earth's, about 5,4 g/cm³.

Type b - Super-Mercurian
A planet which mass is not quite within the minor planet subclass, however, it is made of dense materials such as metals, making the planet heavier than it appears to be by sheer size - as it would still be smaller than Earth, typically, these planets tend to have large core, surrounded by a thin mantle and rocky crust. Could also be more commonly found on the inner part of their systems.

A planet composed of 75% metals and 25% silicates would have density of ~7 g/cm³.

Type c - Martian
A planet which mass within the minor planet subclass, likely around the outer boundary of 0,1 Me, having a rocky composition and a metallic core, being substantially less dense than Earth, these planets tend to be rather large relative to their mass but still solid, though most probably geologically dead due lack of strong internal pressures.
Is probable that these worlds form with such a low density by either inhabiting the outer edge of the terrestrial accretion disk, or by having it's mass 'stolen' by a more massive planet nearby.

A planet of such type would have densities between 3,5 ~ 4,5 g/cm³, martian regolith density is about 3,93 g/cm³.

Type e - Vulcanoid
A rocky planet that is close to the star's innermost stable orbit, having no atmosphere at all, may be tidally-locked, if it's close enough to it's star, tidal forcing may heat up the planet to the point it's surface bears strong volcanism.



Classes T and TT - Terran and Superterran
A planet which mass is greater than 0,1 Me and less than 2 Me, or between 2 Me and 10 Me as a Superterran, can be made of metals, silicates, and ices depending on specific composition and location.
Planet's in these classes would have densities between 4,5 ~ and 7,0-ish g/cm³.

The term of this classification is mean atmospheric nature and distance from the star.

Subclass 1 - Dry
A planet with nearly or completely absent liquid water on it's surface.
Type a - Radiated
A planet is so close to it's star that is heavily radiated by it's emission, having no atmosphere at all, may be tidally-locked, if it's close enough to it's star, tidal forcing may heat up the planet to the point it's surface bears strong volcanism.
 
Type b - Barren
A planet that has little to no atmosphere, and has a rocky surface.
 
Type c - Dune
A planet that has some atmosphere, but little to no water, it surface is largely covered by dry deserts.
 
Type d - Desert
A planet that has some atmosphere, and little water, it surface is largely covered by deserts.
 
Type e - Carbonic
A planet that has a considerable atmosphere, largely composed of nitrogen and carbon dioxide, enough to maintain it's mean temperature above the melting point of water. Carbonic planets can be found on the outer habitable zone, but also between the Venus zone and the tropical habitable zone. Such planets would also require active volcanism to cycle the carbon in the atmosphere beyond the absorption capacity of it's soil. Water on Carbonic planets is rather acidic.
 
Type f - Venusian
A planet that has ran into a carbon-cycle runaway greenhouse effect, and has essentially lost all it's water, temperatures are evenly scorching throughout the planet, and pressures are up to hundreds of atmospheres.

Subclass 2 - Moist
A planet with little liquid water on it's surface.

Type a - Moisty Carbonic
A planet has enough water to be a global swamp, too close to it's star to favor other kinds of climates - think 20th century's view on Venus.

Type b - Steppe
A planet has enough water to bear sparse savannah or steppe environments, but too far away from it's star to favor other kinds of climates.


Subclass  3 - Wet
A planet that has an amount of water comparable or superior to that of Earth's.

Type a - Moisty Venusian
A planet that ran into a runaway moist greenhouse effect, has a dense water vapour and carbon dioxide atmosphere, has a rocky surface.

Type b - Steam World
A planet that has a considerable amount of it's mass formed by water, and it's close enough to it's star that a great portion of it is in vapour form, between it's solid surface and the dense water vapour atmosphere, lies an ocean either as a compresible or supercritical fluid depending on the exact pressures and temperatures.
Water may account for up to 5~15% of the planet's mass.

Type c - Water World
A planet that has a considerable amount of it's mass and own radii formed by water. A water world commonly has a hydrogen, water and carbon dioxide atmosphere, after some point into the water mantle, it's now a supercritical fluid, and further down, a layer of ice VI, VII or X depending on the mean temperature, bellow the ice layer, lies a rocky envelope and a metallic or ice core depending on where it formed in the inner system.

Type d - Oceanic
A planet that has a comparable amount of water to that of Earth's, however, don't have as much landmass, having more than 75% of the planet's surface covered by water.

Type e - Tropical
A planet that has a comparable amount of water to that of Earth's, and similar ratio of landmass to ocean ratio (about 1:3) of the planet's surface covered by water.

Type f - Snowball
A planet that has a comparable or superior amount of water to that of Earth's, however, most of it is in ice form, such a planet has either large polar caps, or is mostly frozen.
Some may have an atmosphere and temperature similar to Saturn's moon - Titan, ie, are cold enough to support a methane-cycle analogous to Earth's water-cycle, or other volatile that can exist in liquid form at these temperatures such as Chlorine, and other hydrocarbons.

Type g - Super-Sized Titan
A planet that's 30~50% water ice by volume, having an Earth-sized silicate lower-mantle and an iron core, the upper-mantle is composed mostly of pressurized water, methane, and ammonia ices, it's distance from the star and atmosphere allows a small portion of the surface to be liquid - forming an ocean that's hundreds of kilometers deep. The atmosphere is mostly water vapor, hydrogen, ammonia, methane. and carbon monoxide/dioxide.

Such worlds have densities around 3~4g/cm³, and topping masses comparable to those of Ice Giants, ~15% water and ~85% silicates and metals by weight.
Tectonic activity is locked by the sheer amount of water ice above the rocky material, so some form of cryovolcanism may be the predominant driving force of pseudo-tectonics with pressures over the ice and radiogenic heating involved.

Bodies like these could have formed early in the star system and due perturbations in those early days acquired eccentric orbits, so while they would have wandered far enough from the star to collect volatiles, they also wandered close enough to star so atmospheric escape take away most of free hydrogen.

Type h - Super-Sized Super-Mercury
A planet that has a metal-like density (more than 5 g/cm³ and less than 9 g/cm³), a Terran/Super-Terran size, a mass comparable to that of an Ice Giant - without having a thick atmospheric envelope as one, if it does have one at all depends o where exactly it did formed.
 
Type i - Cold Venusian
or Cold Primordial
A rocky planet with a dense atmosphere - mainly composed of nitrogen, carbon dioxide, methane, other volatiles and trace gases, can contain hydrogen.
This type of planet could actually be common in young star systems, with orbits on the outer regions of the habitable zone, the atmosphere is thick enough so the planet doesn't freeze but it's not hot enough to trigger runaway greenhouse effect.
Marked by extreme temperature differences between daytime and night-time on the order of ~100K, the thick cloud cover would make little to no light get through the atmosphere. I would say this world-type is an Acheron-analogue.
 

Class N - Mini-Neptune
A planet which is composed mostly of volatiles other than water, like ammonia and methane, are usually found to be short period planets around their stars, forming before the frost line.
A Mini-Neptune mass range from ≳1 Me to 20 Me, the major definition turns around it's size and composition. Mini-Neptunes are identical in composition to Ice Giants (about 20% Hydrogen/Helium and 80% Volatiles), however they are smaller than 3,9 Re and greater than 1,6~1,7 Re.

Type 1 - True Mini-Neptune
A planet that more or less attends the general rule of composition for an Ice Giant.
By mass, 60% mix of supercritical Water, Ammonia and Methane, ≲20% mix of Hydrogen, Helium and Methane gas, ~20% icy/rocky core.

Type 2 - Super-Sized Water World (or Wet-Neptune)
A planet that DOES NOT attends the general rule of composition for an Ice Giant, nor is as big as one, however, the amount of volatiles is so considerably large that it falls in between a TT3c planet and a N1-class planet, having a rocky/metallic bulk mass, a supercritical/liquid water envelope, and thick hydrogen/helium atmosphere - no pressurized Ice, being roughly 2~3 Re wide, with an atmospheric envelope no thicker than 0,5 Re.


Class J - Ice Giant
A planet which is composed of mostly of volatiles other than water, like ammonia and methane.
An Ice Giant mass range from ≳10 Me to 130 Me, the major definition turns around it's size and composition. Ice Giants are made of about 20% Hydrogen/Helium and 80% Volatiles, and attain to sizes greater than 3,9 Re and less than 8,4 Re, densities range on about 1~2 g/cm³.
An Ice Giant's general azure~cyan appearance is due to methane traces in it's atmosphere. Ice Giants aren't restricted to form beyond the frost line, however when they form before the frost line it is very close to their parent stars, those are called Hot-Neptunes then.

Type 1 - True Ice Giant
An Ice Giant that sits beyond the frost line, like Neptune and Uranus.

Type 2 - Hot-Neptune
A short-period (year is less than 10 days and longer than 1 day) planet rich in volatiles, with too much atmosphere to be a Steam World, too big to be Mini-Neptune, and too heavy to be Gas Dwarf.

Hot-Neptunes with radii greater than 2 and less than 10 Re are relatively scarce and the most common type of planet when looking at orbital distances of less than 0,1 AU, creating what's called a Hot-Neptune Desert, planets within these radii, are rarely found between the following lines - most exoplanets with these radii cram just around the border of this zone.
In case your planet fall inside the Hot Neptune Desert, increase the orbital period / distance to an acceptable degree of at least 0,5 log10 into the desert.


Upper Limit Log10(MJ) = [1,07 * Log10(period in days)] - 2
Lower Limit Log10(MJ) =  - Log10(period in days) + 0,1



Class G - Gas Giant
A planet which is composed of mostly of Hydrogen and Helium, having some amount of volatiles like water, ammonia and methane.
A Gas Giant can be as light as ≳10 Me or as heavy as 4.134 Me (beyond that they're classified as Brown Dwarfs), Gas Giants have their atmospheres made up of ≳90% Hydrogen/Helium, nas less than 10% volatiles, a small amount of their mass comes from a solid rocky/metallic core, Gas Giants have strong magnetic fields and make perfect magnetic shields for habitable moons around them.

Type 1 - Lesser Gas Giant
A planet which is mostly made of Hydrogen alone (about ≳95%), ≲5% Helium, and less than 1% trace volatiles.
Lesser Gas Giants are very light like Saturn, having densities from anywhere less than 1,32 g/cm³ and around 0,7 g/cm³ (about as light as Saturn), and at first seem featureless, depending on how low is the concentration of volatiles and tholins in the atmosphere.
Bellow a relatively thin gaseous atmosphere (compared to their size), lies a mantle of liquid supercritical hydrogen, and at the center a rocky core about the size and mass of a Superterran.

Type 2 - Jovian Gas Giant
A planet that is similar in composition to Jupiter, 90% Hydrogen, 10% Helium, and less than 1% trace volatiles.
Jovian Gas Giants are rather heavy when compared to Lesser Gas Giants, their density wander above 1 g/cm³ and less 2 g/cm³, and they might have or not a solid Superterran-sized core depending on where and how it formed.
Jovian Gas Giants have a higher concentration of tholins and other chromophores (like ammonia and sulfur) than it's lighter counterpart, then, it's atmospheric bands appear to be tinted in red/orange/pink depending on the concentration of the materials in it.
Planet's with a mass higher than that of Jupiter aren't much larger than the planet, as the pressures involved kick electron degeneracy in the core, allowing atoms to pack more tightly, so instead of growing in size, they get denser until when they reach 13 Jupiter masses, at start to fuse deuterium.

Type 3 - Inflated Gas Giant
A planet that can be even lighter than a Lesser Gas Giant, due thermal expansion of it's atmosphere for being so close to it's star.
It's worth noting that planets with considerably less gravity or mass than Jupiter (around 24,8m/s²), when exposed to temperatures around 1800K or more will have their  atmospheres evaporated in the timescale of 1~2 billion years.

Gas giants in general (up to 10 Mj) seem to have similar sizes (0,85 to 1,15 Rj) at T <1000K, once the temperature
A reasonable radius estimate for any gas giant at a given temperature is given by:

RJupiter = 0,915 * ( 1,00027 ^ T )

Where T is the temperature in K.
Of course, aspects such as distance from the star, albedo and exact composition are ignored in this case, but it seems to offer quite a solid baseline in that aspect - further bellow you can sort out your gas giant by mass range and calculate it's radius within a 0,2~0,7 Rj margin for variance based on actual exoplanet catalog work - but that's also under the same limitations.

Type 4 - Gas Dwarf
A rocky planet that has a considerable amount of it's mass and volume due to high concentrations of Hydrogen and Helium in a thick atmospheric envelope, however it's atmosphere also contains high levels of volatiles such as ammonia, water, and methane - a Gas Dwarf also isn't as massive or large as a Gas Giant, being similar in size to Hot-Neptunes and Super-Earths.

Due their low density and low gravity - is rather probable that most Gas Dwarfs are in the most part featureless planets, the hotter ones would have a hyper-inflated haze-like atmosphere envelope, while the colder ones could have pale colored bands according to it's rotational period and chromophores in the atmosphere.
Their radii vary in between 1,2 ~ 3,9 Re, and minimum mass of 0,6 Me.
(Kepler 138d is the smallest known Gas Dwarf with 1,2 Re).

A Gas Dwarf with 1,0 Me and a density comparable to that of Saturn would have a radius of 2,0 Re.

Type 5 - Helium Titan
A planet that has a considerable amount of it's mass and volume due to high concentrations of Helium, it would be mostly made of supercritical helium and hydrogen, being ~4x as dense and ~4x as heavy as an usual Gas Giant.
Such a planet could compact 318 Me within only 7,75 Re, presenting a nearly featureless pale or gray appearance due lack of methane, that would otherwise give it a bluish tint.

In nature, the more likely way these planets form is via the Hydrogen evaporation of Hot-Neptunes and Hot-Jupiters, as a late stage of these planets life, a Helium Titan can form within a couple million years, but take up to 10 billion years to lose all of it's hydrogen, so it is possible that most of these planets still contain a large portion of hydrogen, thus, appearing as either pale jovians or a jovian-sized ice giant due methane scattering of light.

SUBTYPES (Sudarsky Classification)
S I
The planet is beyond the frost line, and it's atmosphere color is defined chemically rather than physically, temperatures are less than 150 K, and albedo range from 0,57 w/o tholins and 0,34 w/ tholins.
S II
The planet is close enough to it's star that it's clouds are made of water vapour and methane, giving it a more featureless and pale color, temperatures are less than 250 K, albedo is around 0,81.
S III
The planet is so close to it's star that the incoming solar radiation decompose cloud formations, giving it a more featureless and azure~cyan appearance due sheer Rayleigh scattering, temperatures are less than 800 K but more than 250 K, above 700 K the presence of sulfides and chlorides favor the formation of thin cirrus-like clouds, with an albedo as low as 0,12.
S IV
The planet is close enough to it's star that the main component of the upper atmosphere changes to carbon monoxide and other alkali metal impurities, which darkens the planet, having an albedo low as 0,03, temperatures are above 900 K. Those are commonly called Hot-Jupiters.
S V
The planet is either a super Hot-Jupiter, with temperatures above 1400 K, or cooler and less heavy than Jupiter, with silicate and iron clouds, and albedo at 0,55.


POTENTIALLY HABITABLE PLANET TYPE SUMMARY
  • S2c type
  • T1 and TT1, c through f types
  • T2 and TT2, a and b types
  • T3 and TT3, a through f types
  • G4, subtype S-III

Other Multi-Class Types

Eyeball Planet
A planet within the Subterran-Superterran mass range, granted it does have an atmosphere and some amount of liquid water, and sufficiently close to it's star, usually a Red Dwarf, it will be tidally-locked, creating a desert hemisphere and a water ice hemisphere, having a thin temperate zone around it's terminator. Such planets are bombarded with radiation and charged particles from it's parent star, however, if it does have a sufficiently strong magnetic field, it could harbor complex life.

Rock/Ice Puffy Planet
A planet that has a density comparable to that of the Moon or an asteroid (less than 3,5 g/cm³), generally nearly or completely absent of metals and composed mainly of silicates and ices.
Puffy planets of this kind have a weak gravity when compared to Sub, Terran, and Super Terran counterparts of the same size, because of that, are probably geologically dead on their own. This kind of body is found in the solar system as the icy moons of Jupiter, and tidal heating could make them habitable to some extent.

Classifying Terran-Sized planets by Water Content
A planet within the S throughout TT classes could be also classified by it's water content, proportionally speaking - because it doesn't help much having as much water as Earth if the planet has 4x as much area, making for a lower water content, or if the planet has half the water on Earth, but have 1/3rd of the area - making for a relatively larger water content.

In this classification, I will be referring to the Mars water proportion to it's mass, ie how much of the planet's mass is made of water.

Color-codes for habitability assumes the planet that much liquid water in a stable temperature and pressure for life as we know it.
DRY
Dry - < 0,0000024%

Martian-dry - around 0,0000032%
MOIST
Moist I - up to 0,00032%
Moist II - up to 0,002%

WET
Oceanic I - up to 0,01%
Oceanic II - around 0,023%
Earth goes here.
Oceanic III - 0,04%

SOAKED
Water World I - 0,07%
Water World II - 0,2%
Water World III - 5~15%
At this point the planet has at least 5% of it's mass composed by water, and above 15% we can consider it a True-Water-World (a T3c or TT3c planet).
Earth-like biochemistry is difficult with 0,1% of the planet's mass worth of water.
Tectonic activity stops once the water amount is above ~1,1% of the planet's mass, so chemosynthesis would also be difficult, if not, non-existant beyond this point.

RELATIONSHIP GRAPHS

Here is a graph of planetary mass in Earths x Volatile content in percent.
Earth posess 0.02% of its mass in water, and so we get -1.7 in the vertical axis, and zero in the horizontal axis since the log of 1 is 0 (0.0,-1.7).
Mars has coordinates (-0.97, -5.49)

 
Planetary Density as a function of it's distance from the Sun

 
Minor Planet Density Zones

Dwarf Planet Mass/Size Relationship
 Gas Giant planet Radius x Temperature

Gas Giant planet Radius x Temperature - but it's my attempt to find a relationship

Metal/Silicate Ratio and respective representative densities - metallic material is assumed to be 8,05g/cm³ and silicate material to be 2,75gcm³

- M.O. Valent, 15/09/2020
- M.O. Valent, updated 27/09/2020

HIGHLIGHTS

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