Kerbals are Giants

[Northstar1989]

I know this may actually seem counter-intuitive, considering their small size, but Kerbals are actually giants compared to their environment...

I was doing some math to try and figure out estimated worst-case scenario casualties from a direct impact of a Class C asteroid into Kerbin (as luck would have it, one of the first asteroids I ever tracked turned out to be a Class C on a 60-90 degree re-entry collision course entering Kerbin's SOI in about 57 days...) To do this, I actually had to figure out what Kerbal population densities might be relative to Earth's, based on their physical stature in regards to their planetary radius. And, as it turns out, Kerbals are HUGE...

Some numbers I was working with:

- The Kerbol system (Kerbin and the other planets) is a bit less than 1/10th scale the real solar system. Kerbin has a radius of 600 km, whereas Earth has a radius of 6,353 km)

- Stock Parts, are at 64% scale of their real-world counterparts. The Kerbals themselves, however, only stand at about 0.75 meters tall according to the Wiki- which means there are 42.23% the height of the average American male in his twenties (177.6 cm), for a comparison. So, rounding down a bit as Americans are a little taller than the average human (due in large part to the average height in Asia), let's say Kerbals are about 40% the size of a modern-day human male...

Therefore, Kerbals are a bit over FOUR TIMES the size of a human relative to his environment! If a Kerbal were scaled to Earth, he would stand over 7 meters (22.97 feer) tall!

This meant for my asteroid-impact casualty-estimates, I needed to divide casualties by 2.5- as larger creatures have lower population densities... It also mean though, that despite Kerbals appearing cute and tiny, they are actually HUGE compared to their environment!

Regards,

Northstar

P.S. Oh, and by the way, applying the 10x scale to a Class C asteroid, you get a 70-100 meter asteroid instead of a 7-10 meter asteroid. The Tunguska asteroid was in this size range (60- 190 meters according to Wikipedia, http://en.wikipedia.org/wiki/Tunguska_event), and it wiped out trees over a land area of more than 2,150 sq. km! It also entered the atmosphere by a *VERY* shallow re-entry trajectory, and so its explosive force when it airburst was "only" that of 10-15 Megatons of TNT, instead of the average of 38 Megatons for an 100-meter asteroid entering at a 45-degree angle (http://en.wikipedia.org/wiki/Asteroid_impact#Frequency_and_risk). You might want to re-think just how "harmless" a Class C asteroid is next time you see one hurtling towards Kerbin!

P.P.S. With the laughingstock that is the current aerodynamics model, asteroids of any size aren't actually that dangerous- since drag exerted on them scales with their mass instead of their cross-sectional area in the stock model. If you're running FAR on the other hand, the larger asteroids should be able to reach the lower atmosphere at realistically enormous speeds, as big spheres of rock have very little cross-sectional area compared to their mass... With FAR, asteroids also become exponentially more dangerous as their size increases, like in real life- as the larger ones experience a lot less drag from the atmosphere relative to their mass...

Edited May 15, 2014 by Northstar1989

[SlimeCrusher]

Wow... The first thing that came into my mind was a godzilla-sized Kerbal destroying all the buildings screaming "WHERE ARE THE SNAAAAACKS?!?!" lol

[RW-1]

I've always appeared cute, but was never described as "Tiny" by the women .....

Wouldn't the explosive force of an asteroid also be in part due to its composition? Maybe some of ours are composed of light grey Styrofoam ...

Edited May 15, 2014 by RW-1

[Northstar1989]

Wow... The first thing that came into my mind was a godzilla-sized Kerbal destroying all the buildings screaming "WHERE ARE THE SNAAAAACKS?!?!" lol

Haha, yeah- something like that came to my mind too...

And you posted your reply before I fixed a math fail in my calculations- see the fixed estimate of how tall a Kerbal would stand on Earth! (7 meters tall, not 3!)

Regards,

Northstar

[Northstar1989]

I've always appeared cute, but was never described as "Tiny" by the women .....

Wouldn't thh explosive force of an asteroid also be in part due to its composition? Maybe some of ours are composed of light grey Styrofoam ...

Yes, the explosive airburst or impact force is also based on the composition. Metallic asteroids (only approximately 8% of all asteroids) are *MUCH* more dangerous (as they are more than twice as dense), for instance.

The figure I gave in the footnote for the explosive force in the lower atmosphere (not the asteroid's kinetic energy at atmospheric re-entry, which is higher) of a 100-meter asteroid was based on the density of an average rocky asteroid, according to Wikipedia... A metallic asteroid would be a LOT more than twice as deadly relative to its volume! (due to its higher density, it would experience less drag relative to its mass...)

Regards,

Northstar

P.S. Based on the decreases in the surface area exposed to drag with increasing size, and relative to mass with metallic asteroids, it appears that moderately-large metallic asteroids actually could easily reproduce the kind of spectacular flames in the lower atmosphere for a meteor that are normally only seen in Hollywood and fiction... (We also see flames like these during re-entry of smaller asteroids, most of them the size of grains of sand, in meteor showers... However they only flame like this in the uppermost reaches of the atmosphere- due to their small size they either burn up or slow down long before reaching the lower atmosphere...)

Edited May 15, 2014 by Northstar1989

[Geschosskopf]

I know this may actually seem counter-intuitive, considering their small size, but Kerbals are actually giants compared to their environment...

A very interesting observation. And definitely another nail in the coffin of applying humanocentric life support needs to such bizarre and alien "little" aliens .

I wonder about their population density, however. I've flown all over Kerbin and have never observed any Kerbals anywhere, other than inside the buildings of KSC. Otherwise, the only evidence of their existence (besides LKO being full of spent boosters) are abandoned ruins: the "other" KSC, airbase island, and the pyramids. It would therefore seem that their population is in decline and that any impact other than on KSC would do them no damage at all. but that a hit there would totally exterminate them.

[Tw1]

Decided to apply science.

This handsome guy is about 75 cm according to Jeb's big stick. It's clearer in game than in these pictures.

With the helmet on, he's closer to 90cm.

Thought these measurements may not be perfect, as my measuring apparatus was possesed by wiggle horse/kracken.

[Brotoro]

I don't think kerbals would be giants compared to their environments. The surface gravity of Kerbin is the same as Earth, so (assuming normal materials for the outer layers of the planet) you would expect the similar sized mountains, ravines, sand dunes, plant life, animals, etc., compared to what we have on Earth. So 75 cm tall kerbals would be small compared to their environment. But they would have a LOT less living area than we do on Earth because of Kerbin's much smaller surface area.

[SkyRender]

So what you're saying is, they might be giants? That would rock.

[Geschosskopf]

I don't think kerbals would be giants compared to their environments. The surface gravity of Kerbin is the same as Earth, so (assuming normal materials for the outer layers of the planet) you would expect the similar sized mountains, ravines, sand dunes, plant life, animals, etc., compared to what we have on Earth. So 75 cm tall kerbals would be small compared to their environment. But they would have a LOT less living area than we do on Earth because of Kerbin's much smaller surface area.

But we can demonstrate that Kerbin isn't made of "normal" (as in Earth-like) materials. Consider the so-called "water", which well-documented experiments have demonstrated has a density greater than that of neutronium. It is therefore not surprising that there are neither clouds, nor tides, nor even waves on Kerbin, because the oceans are too heavy to move. And the land masses are denser still or else the oceans would have no bottoms, and slightest ripples in the oceans would bulldoze entire continents. All of Kerbin, therefore, is made of some exotic (perhaps "dark") matter, so all our Earthly conceptions of scale are doubtless inapplicable to Kerbin.

Now, if Kerbals are indeed native to Kerbin (a debatable point given their absence from nearly all of it and their inability to go outside without spacesuits), then presumably they themselves are made of this same exotic material. "Dust thou art and dust thou wert and to dust thou shalt return." Kerbals, of course, do indeed "return to dust", although a competing theory holds that this "dust" is a cloud of spores. But either way, if Kerbals are made of the exotic stuff of Kerbin, then Earthly scaling rules don't apply to them, either.

[Felsmak]

Maybe a little over the top, but still.

[Brotoro]

But we can demonstrate that Kerbin isn't made of "normal" (as in Earth-like) materials. Consider the so-called "water", which well-documented experiments have demonstrated has a density greater than that of neutronium. It is therefore not surprising that there are neither clouds, nor tides, nor even waves on Kerbin, because the oceans are too heavy to move. And the land masses are denser still or else the oceans would have no bottoms, and slightest ripples in the oceans would bulldoze entire continents. All of Kerbin, therefore, is made of some exotic (perhaps "dark") matter, so all our Earthly conceptions of scale are doubtless inapplicable to Kerbin.

Now, if Kerbals are indeed native to Kerbin (a debatable point given their absence from nearly all of it and their inability to go outside without spacesuits), then presumably they themselves are made of this same exotic material. "Dust thou art and dust thou wert and to dust thou shalt return." Kerbals, of course, do indeed "return to dust", although a competing theory holds that this "dust" is a cloud of spores. But either way, if Kerbals are made of the exotic stuff of Kerbin, then Earthly scaling rules don't apply to them, either.

Nah, kerbals can't be made of exotic neutronium matter... We know their masses, and that doesn't fit.

[NERVAfan]

Yeah, a Kerbal on EVA weighs 90 kg. Assuming half of this is the spacesuit, the Kerbal would be 45 kg... which would still make it denser than a human of the same height. But not incredibly super-dense, more like rocks or metal. Much less dense than Kerbin itself, which is denser than osmium (but still nowhere near neutron star matter or even white dwarf matter densities)

[Mipe]

'Biggest dinosaur ever' discovered

Could it be....? Naaaaah.

[Northstar1989]

I don't think kerbals would be giants compared to their environments.

That's the whole point I make in the OP. They are if you do the math.

The surface gravity of Kerbin is the same as Earth

Indeed, but the planet is 10% the size... Earth's radius is over 6,000 km (6353 km, to be precise), whereas Kerbin's is only 600 km.

so (assuming normal materials for the outer layers of the planet) you would expect the similar sized mountains, ravines, sand dunes, plant life, animals, etc., compared to what we have on Earth.

It's less a matter of the size of terrain features than the amount of actual square footage of land area available. Cities are built in flat areas- for obvious reasons. The fact that Kerbin only less than 10% the radius means it has a lot less available space. Kerbals are larger compared to the total land area of the planet...

Surprisingly, though, the features of Kerbin are completely out of proportion with its greatly reduced size. For instance, the tallest peak on Earth is Mount Everest, at 8,848 m. The tallest peak on Kerbin is still about 75% as tall- 6761 m...

So 75 cm tall kerbals would be small compared to their environment. But they would have a LOT less living area than we do on Earth because of Kerbin's much smaller surface area.

I'm a biologist in real life. So I'm going to define organism size in one of the practical ways we define it in biology in real life- as organism volume and biomass relative to the available living area (sq. km). By that measure, Kerbals are absolutely gigantic- once again, if scaled to Earth, they would stand over 7 meters tall!

Regards,

Northstar

[Northstar1989]

I'm impressed with the level of humor and foolery that this thread prompted though. It's good to see that KSP players still know how to be funny- even as they're sending these ginormous walking cacti to their maniacally grinning deaths.

Regards,

Northstar

P.S. Starting this thread actually got me thinking about what would be the most realistic way to scale up Kerbin and the other planets to an Earth/Sol-like star system... Would it be to simply scale to up the parameters to the real ones, like in the classic Real Solar Systems config version, or would it be to scale it up by 6.4:1 scale (that is, to 64% of the size of the real planets- another available RSS config), in keeping with the part's 64% size compared to their approximate real-life counterparts? Or would it be best to scale relative to the Kerbals- in which case Kerbin would actually need to be made 4 times LARGER than Earth...

Edited May 18, 2014 by Northstar1989

[Special Agent Sigvan]

A very interesting observation. And definitely another nail in the coffin of applying humanocentric life support needs to such bizarre and alien "little" aliens .

I wonder about their population density, however. I've flown all over Kerbin and have never observed any Kerbals anywhere, other than inside the buildings of KSC. Otherwise, the only evidence of their existence (besides LKO being full of spent boosters) are abandoned ruins: the "other" KSC, airbase island, and the pyramids. It would therefore seem that their population is in decline and that any impact other than on KSC would do them no damage at all. but that a hit there would totally exterminate them.

Low Kerbin Orbit has spent boosters in it?

Also, there is a second (Or third) KSP, install the Lazor system mod and there's a point called KSP 2.

Also, the Kerbals are only slightly shorter then the Grass terrain scatter.

This math was unnecessary...

[Geschosskopf]

Yeah, a Kerbal on EVA weighs 90 kg. Assuming half of this is the spacesuit, the Kerbal would be 45 kg... which would still make it denser than a human of the same height. But not incredibly super-dense, more like rocks or metal. Much less dense than Kerbin itself, which is denser than osmium (but still nowhere near neutron star matter or even white dwarf matter densities)

Well, the Kerbals can foam-like, mostly air held in place by a very then structure of uber-dense material.

And neutronium floats in the oceans. Create a part with the density of neutronium, drop it in the ocean, and you still need a rocket on top to make it submerge. Archimedes says things float because they're less dense than the water they displace. Therefore, Kerbin's oceans are denser than neutronium. And because the oceans have bottoms, the dirt is denser than the oceans.

In any case, it's a totally alien planet where nothing seems to make sense. Therefore, there's no way we can apply human norms to Kerbals

[Northstar1989]

Well, the Kerbals can foam-like, mostly air held in place by a very then structure of uber-dense material.

And neutronium floats in the oceans. Create a part with the density of neutronium, drop it in the ocean, and you still need a rocket on top to make it submerge. Archimedes says things float because they're less dense than the water they displace. Therefore, Kerbin's oceans are denser than neutronium. And because the oceans have bottoms, the dirt is denser than the oceans.

In any case, it's a totally alien planet where nothing seems to make sense. Therefore, there's no way we can apply human norms to Kerbals

Making me chuckle as always Geschosskopf...

How's the Kethane Traveling Circus doing, by the way? Care to plug it to all the readers of this thread of mine?

Regards,

Northstar

[Captain Sierra]

And neutronium floats in the oceans. Create a part with the density of neutronium, drop it in the ocean, and you still need a rocket on top to make it submerge. Archimedes says things float because they're less dense than the water they displace. Therefore, Kerbin's oceans are denser than neutronium. And because the oceans have bottoms, the dirt is denser than the oceans.

In any case, it's a totally alien planet where nothing seems to make sense. Therefore, there's no way we can apply human norms to Kerbals

This could explain why Kerbin is able to generate such high gravity for it's mass.

By my calculations, Kerbin's radius is 298 times smaller than that of earth.

For simplicity, I assumed it was a roughly perfect sphere, giving a total volume of ~3590000 cubic meters

The Earth is ~1097509500000000000000 cubic meters, according to NASA.

This means that the earth has 305712952646239.6 times as much volume.

Assuming the same laws of physics still apply, then that means Kerbin and Earth must both be 5972190000000000000000000kg.

The density of Earth is 1.217kg per cubic meter. We can calculate the density of Kerbin to be 1663562674094707520.9kg per cubic meter.

Now I don't know for sure, but that sounds like black hole density to me. I'm not even sure what to make of that.

[Gojira]

Maybe a little over the top, but still.

[snip]

"And on that day, Kerbalkind recieved a grim reminder..."

[MockKnizzle]

This could explain why Kerbin is able to generate such high gravity for it's mass.

By my calculations, Kerbin's radius is 298 times smaller than that of earth.

For simplicity, I assumed it was a roughly perfect sphere, giving a total volume of ~3590000 cubic meters

The Earth is ~1097509500000000000000 cubic meters, according to NASA.

This means that the earth has 305712952646239.6 times as much volume.

Assuming the same laws of physics still apply, then that means Kerbin and Earth must both be 5972190000000000000000000kg.

The density of Earth is 1.217kg per cubic meter. We can calculate the density of Kerbin to be 1663562674094707520.9kg per cubic meter.

Now I don't know for sure, but that sounds like black hole density to me. I'm not even sure what to make of that.

Ummmm, I'm not sure how to tell you this, but your calculations are incredibly, horribly wrong.

Kerbin radius: 600 km

Earth (mean) radius: 6371 km

Kerbin is 9.4% of the Earth's radius, or just under 1/10th the size.

Assuming the planets are simple spheres: V = 4/3*pi*r³

Kerbin volume: 9.0478 x 10^17 m³

Earth volume: 1.0832 x 10^21 m³

Kerbin is 0.08% or about 1/1000 Earth's volume.

Kerbin mass: 5.2916 x 10^22 kg (no idea why you thought Kerbin and Earth have the same mass...)

Earth mass: 5.9726 x 10^24 kg

Kerbin average density: 58,485 kg/m³

Earth average density: 5,514 kg/m³

Kerbin has an average density 10.6 times that of Earth.

[Geschosskopf]

Kerbin has an average density 10.6 times that of Earth.

So to explain the observed phenomena on Kerbin's surface vis the incredible densities, we must assume that Kerbin's mass is far from evenly distributed. It's got an uber-dense shell around lighter core. I'm sure Kerbal boffins liken it to some sort of cream-filled candy or baked meringue .

This would make for all sorts of weird effects. With nearly all its mass concentrated in the thin outer shell, Kerbin is a huge flywheel with an obscene amount of angular momentum. No wonder Mun is tidally locked, and I rather doubt that Kerbin's day will ever increase in length due to its drag. In fact, the day recently got shorter by 75% . I assume there would also be bizarre gravitational effects on Kerbin itself (akin to those on Mesclin in A Mission of Gravity), which might explain the un-Earthly behavior of Kerbin's atmosphere.

But this brings up an interesting question. Presumably Tylo has a similar structure to Kerbin, yet it seems to be tidally locked to Jool. Jool seems to be built on more conventional lines, getting denser towards the middle. So where did Tylo's angular momentum go?

[Brotoro]

There aren't any observed phenomena of incredible densities on Kerbin's surface. I think before that you mentioned something about the water having an incredible density, but this is not the case. We know the masses of spacecraft parts (since the game will give you the mass of your ship), and a capsule floats partially submerged in the water as expected (instead of hardly submerged at all, as it would if the liquid in the oceans had extremely high density). Kerbals also float partially submerged in the water (and we know the mass of kerbals from game data). All we see when we get floating I-beams and such is crappy modeling of floatation physics and water behavior (including no implementation of tides). You also mention something about a lack of clouds on Kerbin…but I see clouds outside the VAB door (they just aren't included in the rest of the game yet, but considering how well mods can do at adding clouds without a great CPU hit, I expect that clouds will be added eventually).

[MockKnizzle]

I'm in agreement with Brotoro on this one, Geschosskopf... looking at the game's half-finished parts and trying to extrapolate physical laws from them doesn't give you anything that makes sense. I know you're mostly just being silly, but trying to explain the aerodynamic model or flotation physics as anything other than "incomplete" is gonna give you nonsense.