Kerbin

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Kerbin
Kerbin
Kerbin as seen from orbit.
Planet of Kerbol
Orbital Characteristics
Semi-major axis 13 599 840 256 m [Note 1]
Apoapsis 13 599 840 256 m [Note 1]
Periapsis 13 599 840 256 m [Note 1]
Orbital eccentricity 0
Orbital inclination 0 °
Argument of periapsis 0 °
Longitude of the ascending node 0 °
Mean anomaly 3.14 rad (at 0s UT)
Sidereal orbital period 9 203 545 s
426 d 0 h 32 m 24.6 s
Synodic orbital period Not defined
Orbital velocity 9 285 m/s
Physical Characteristics
Equatorial radius 600 000 m
Equatorial circumference 3 769 911 m
Surface area 4.5238934×1012 m2
Mass 5.2915158×1022 kg
Standard gravitational parameter 3.5316000×1012 m3/s2
Density 58 484.090 kg/m3
Surface gravity 9.81 m/s2 (1 g)
Escape velocity 3 431.03 m/s
Sidereal rotation period 21 549.425 s
5 h 59 m 9.4 s
Solar day 21 600.000 s
5 h 59 m 60 s
Sidereal rotational velocity 174.94 m/s
Synchronous orbit 2 863.33 km
Sphere of influence 84 159 286 m [Note 1]
Atmospheric Characteristics
Atmosphere present Yes
Atmospheric pressure 101.325 kPa
1 atm
Atmospheric height 70 000 m
1.0×10-6 atm
Temperaturemin -86.20 °C 186.95 K
Temperaturemax 15 °C 288.15 K
Oxygen present Yes
Scientific multiplier
Surface 0.3
Splashed 0.4
Lower atmosphere 0.7
Upper atmosphere 0.9
Near space 1
Outer space 1.5
Recovery 1
  1. ↑ 1.0 1.1 1.2 1.3 The distances are given from the body's center, not from the surface (unlike ingame)
  1. SaveKSP2

Kerbin is the home planet of the Kerbals, the location of the Space Center and other facilities, and the main focus of Kerbal Space Program. It is also the Earth analog for the game but, unlike Earth, it has two moons instead of one. They are named the Mun and Minmus. It is the planet you start your game on, being home to the KSC, where you construct and launch your vehicles on.

Kerbin, the home planet in Kerbal Space Program, boasts two natural satellites: the larger Mun and the smaller Minmus. The Mun, resembling Earth's moon, is characterized by its gray, cratered surface, offering ample opportunities for exploration and scientific research. In contrast, Minmus is a unique celestial body with a mint-green hue and low gravity, making it an ideal location for mining operations and testing advanced rover technologies. Both moons orbit Kerbin in slightly eccentric orbits, providing players with diverse challenges and objectives for their space missions.

Kerbin is the third planet in orbit around the star Kerbol. It is the third largest celestial body that orbits Kerbol, following Jool and Eve. Jool's moon, Tylo has the same radius of Kerbin, though it may be classified as larger, as the highest point on Tylo is about 5 km higher than the highest point on Kerbin. However, Tylo has only 80% of Kerbin's mass.

Reaching a stable orbit around Kerbin is one of the first milestones a player might achieve in the game. With the introduction of version 1.0.3, attaining low Kerbin orbit requires a Δv of approximately 3400 m/s, though the exact amount depends on the efficiency of the ascent profile and the aerodynamics of the launch vehicle and payload. The only rocky planet that requires a higher Δv to attain orbit is Eve due to it's dense atmosphere and higher gravity. Many interplanetary missions expend over half of their Δv in reaching Kerbin orbit. The velocity required to escape a body from a given altitude is always exactly the square root of two, times the velocity of a circular orbit around the body at that height: .

In-game description

KSP 1:

“ A unique world, Kerbin has flat plains, soaring mountains and wide, blue oceans. Home to the Kerbals, it has just the right conditions to support a vast, seemingly undepletable population of the eager green creatures.


Reaching a stable orbit around Kerbin is one of the first things budding space programs strive for. It is said that those who can get their ship into orbit are halfway to anywhere.''

— Kerbal Astronomical Society

 ”

KSP 2:

“ Even as rockets and probes escape its atmosphere for deep space exploration, there is still much to appreciate about this vibrant world. Its vast oceans, deserts, forests, and plains coat the surface in lively beauty. Its moons, Mun and Minmus, swirl silently above it. Kerbalkind is fortunate to call this pale blue planet their home. ”

Topography

Topographical representation of Kerbin's surface as of 0.18.2. Click for high resolution. by Zeroignite
Kerbal at Kerbin's highest peak(old)
A Kerbal at Kerbin's highest peak(1.12.2)

Kerbin has a roughly equal distribution of liquid surface water and solid land, with polar ice caps and scattered deserts. Some of its mountains exceed 6 kilometers in height, with the tallest peak being 6767.4 m in altitude at the coordinates 46°21'32" E 61°35'53" N. The lowest point is almost 1.4 km deep and about 313° south-west of the Kerbal Space Center.

Craters

Terrain model centered on Kerbin's most pronounced craters

Unlike other bodies in its system, Kerbin has few visible craters because its environment would erode craters from the few meteors that avoid the gravity or surface of its large moon and survive entry. Nevertheless, some geological formations indicate that bodies have violently collided with Kerbin: a planetary feature appears to be an impact crater, while a secondary rupture lies on the other side of the planet (made by the intense longitudinal, or P-wave earthquakes that ensue.) Both are in excess of 100 km diameter, and the main crater lies along the far-western coastline. The uplift is easily visible as a series of islands, and the feature has a central peak that pokes up through the water (also known as a rebound peak.) The other, and smaller of the two, is near the prime meridian in the northern hemisphere and is more easily missed, but its uplift rims are visible, and it also has a central rebound peak.

Biomes

After the Mun, Kerbin is the celestial body with the second-highest number of biomes. Science experiments can be performed in all biomes, though Kerbin's low multipliers result in less impressive results than more distant worlds. Kerbin's biomes show a loose correlation with Earth's biomes and geographic features. Uniquely, Kerbin has 33 location biomes at KSC, these are comprised of each building and their props, the crawlerway, the flag, and KSC itself; these give a jumpstart to gathering Science points in Career mode. With 1.2 Kerbin had distinct Northern and Southern Ice Shelves added.

Kerbin biome map as of 1.2

List of biomes

  • Ice Caps
  • Northern Ice Shelf
  • Southern Ice Shelf
  • Tundra
  • Highlands
  • Mountains
  • Grasslands
  • Deserts
  • Badlands
  • Shores
  • Water

KSC mini biomes

Atmosphere

Temperature and pressure of Kerbin's atmosphere as a function of altitude.
Drag force is proportionate to atmospheric density.
File:Measures of Kerbin's atmospheric pressure
Measures of Kerbin's atmospheric pressure

Kerbin has a thick, warm atmosphere with a mass of approximately 4.7×1016 kilograms, a sea level pressure of 101.325 kilopascals (1 atmosphere), and a depth of 70,000 meters. The atmosphere contains oxygen and can support combustion. Kerbin is one of the two celestial bodies (the other one being Laythe) with a breathable atmosphere.

The average molecular weight of Kerbin air is 28.9644 g/mol, and its adiabatic index is 1.40. This suggests that Kerbin likely has an earthlike nitrogen-oxygen atmosphere. The air-fuel ratio of jet engines operating in Kerbin's atmosphere suggests that the percentage of oxygen is similar to that of Earth's atmosphere (about 21%).

Like all other atmospheres in the game, Kerbin's atmosphere fades exponentially as altitude increases. The scale height varies with altitude, which is a change from pre-1.0 versions of the game. The pressure-altitude profile is globally constant and independent of temperature. The following table gives the atmospheric pressure and density at various altitudes above sea level. Temperature-altitude profile is not globally constant, therefore neither is the density-altitude profile, however variance is slight.

Altitude (m) Pressure (Pa) Pressure (atm) Density (kg/m^3)
0 101 325 1.000 1.225
2 500 69 015 0.681 0.898
5 000 45 625 0.450 0.642
7 500 29 126 0.287 0.446
10 000 17 934 0.177 0.288
15 000 6 726 0.066 0.108
20 000 2 549 0.025 0.040
25 000 993.6 0.010 0.015
30 000 404.1 0.004 0.006
40 000 79.77 0.001 0.001
50 000 15.56 0.000 0.000
60 000 2.387 0.000 0.000
70 000 0.000 0.000 0.000

Kerbin's atmosphere can be divided into three major layers, comparable to Earth's troposphere, stratosphere and mesosphere. In the lower and upper layers, temperature decreases as altitude increases, while the middle layer spans of a region of increasing temperature. The boundary between the lower and middle layers occurs at an altitude of about 16 km at low latitudes, and about 9 km at high latitudes. The boundary between the middle and upper layer occurs at an altitude of about 38 km.

Air temperatures vary with latitude and time of day. At the equator, sea level temperatures vary between a nighttime low of 32 °C and a daytime high of 41 °C. At the poles, the temperature varies between -35 °C and -30 °C. The globally averaged sea level temperature is approximately 13.5 °C. Since Kerbin has no axial tilt, there are no seasonal temperature variations.

The atmosphere of Kerbin is patterned after Earth's U.S. Standard Atmosphere (USSA), though with the vertical height scale reduced by 20%. Kerbin's "base" temperature and atmospheric pressure can be very closely approximated using the equations of the USSA, where Kerbin's geometric altitude, z, is converted to Earth's geopotential altitude, h, using the equation:

.

The base temperature is the temperature less latitudinal and diurnal adjustments; it is roughly equal to the global mean temperature.

Atmospheric flight

The thickness of Kerbin's atmosphere makes it well suited for aerobraking from a high-speed interplanetary intercept. The periapsis altitude required for a successful aerocapture depends on the spacecraft's drag characteristics, its approach velocity, and the desired apoapsis of the resulting orbit. For most conditions, a periapsis altitude of about 30 km should result in an aerocapture.

Parachutes perform well in Kerbin's dense air, allowing landings on both land and water to be accomplished without the aid of propulsion.

Because of the presence of oxygen, jet engines can operate in Kerbin's atmosphere. And, together with its thickness, Kerbin's atmosphere is ideally suited for aircraft flight.

A modified Orbiter 1A prepares to dock with a space station.

Orbits

A Sputnik-derived satellite

A synchronous orbit is achieved with a semi-major axis of 3 463.33 km. Kerbisynchronous Equatorial Orbit (KEO) (or geostationary), has a circularly uniform altitude of 2 863.33 km and a speed of 1 009.81 m/s. From a 70 km low equatorial orbit, the periapsis maneuver requires 676.5 m/s and the apoapsis maneuver requires 434.9 m/s. A synchronous Tundra orbit with eccentricity of 0.2864 and inclination of 63 degrees is achieved at 3799.7/1937.7 km. Inclination correlates with eccentricity: higher inclined orbits need to be more eccentric, while equatorial orbit may be circular, essentially KEO.

A semi-synchronous orbit with an orbital period of ½ of Kerbin's rotation period (2 h 59 m 34.7 s or 10774.7  seconds) is achieved at an altitude of 1 581.76 km with an orbital velocity of 1 272.28 m/s. A semi-synchronous Molniya orbit with eccentricity of 0.742[1] and inclination of 63 degrees can not be achieved, because the periapsis would be 36 km below the ground. The highest eccentricity of a semi-synchronous orbit with a periapsis of 70 km is 0.693 with an apoapsis of 3100.36 km.

The Hill sphere (the radius around the planet at which moons are gravitationally stable) of Kerbin is 136 185 km, or roughly 227 Kerbin radii.

Low Kerbin Orbit

70 to 1400km

Medium Kerbin Orbit

1400km to 2 863.33 km

High Kerbin Orbit

2 863.33 km to 12000km (Mun altitude)

SHKO - Super High Kerbin Orbit

12000km to 84159km

Delta-V Requirements

From the lowest possible stable orbit around Kerbin (70 km), the average amount of delta-V needed to reach other destinations is:

Body Δv
Mun ~860 m/s
Minmus ~930 m/s
Eve ~1033 m/s
Duna ~1060 m/s
Geostationary Orbit ~1120 m/s
Dres ~1540 m/s
Moho ~1676 m/s
Jool ~1915 m/s
Eeloo ~2100 m/s
Kerbol escape ~2740 m/s

Reference frames

Time warp Minimum Altitude
1× Any
5× 70 000 m (above the atmosphere)
10× 70 000 m (above the atmosphere)
50× 70 000 m (above the atmosphere)
100× 120 000 m
1 000× 240 000 m
10 000× 480 000 m
100 000× 600 000 m

KSP 2

Surface Research Locations

Surface research locations include:

  • Grasslands
  • Highlands
  • Mountains
  • Desert
  • Ice
  • Water
  • Beach

Maps

Biomes

Kerbin biome map with legend (as of v0.2.1.0 (from Orbital Survay mod))

Visual map

File:Kerbin visual.png
Eve visual map (as of v0.2.1.0)

Kerbin visual map (Imgur)


Gallery

Kerbal Space Program

  • Topographical map of Kerbin as of version 0.21

  • A projection map of Kerbin, as of 0.14.1 and before (including the old demo).

  • An accurate full-colour projection map of Kerbin as of 0.14.2 to 0.17.1

  • A map displaying the delta V needed from/to Kerbin

  • Kerbin, Mun and Minmus.

  • Kerbin with its two natural satellites, the Mun and Minmus, seen from KEO. Minmus can be seen just above the horizon of Kerbin on the left side of the picture.

  • A topographic heightmap of Kerbin made with the ISA MapSat plugin

  • Kerbin and the Mun, barely visible from ~500,550,000 m

  • Topographical image of Kerbin from 0.17.1. The terrain is slightly different in the latest version.[2]

  • An unmanned probe on escape trajectory, flying past Kerbin, Mun and Minmus

  • Kerbin's North Pole

  • Kerbin's South Pole

  • A solar eclipse from low Kerbin orbit (LKO).

  • Kerbin and Minmus seen from the surface of the Mun.

  • Kerbin, Mun, and Minmus in a line, seen from a Minmus landing craft.

  • Another picture of the kerbin system, seen from near-Minmus space

Kerbal Space Program 2

  • The horizon of Kerbin in KSP2.

  • Grass on Kerbin in KSP2.

  • Flowers on Kerbin in KSP2.

Spoiler: Easter Eggs Are Shown

  • The second launch site (currently unused).

  • Kerbin from above with the Runway Easter Egg

  • A Crashed UFO on Kerbin's northern ice cap.

Changes

1.10
  • KSC's grass now changes according to the currently set terrain shader quality.
1.2
  • Added biomes.
1.0.5
  • Kerbin spun up to have a 6 hour synodic day.
0.90
  • Updated biomes.
0.22
  • Biomes added.
0.21
  • Terrain revised to produce more detailed and interesting landforms.
0.19.1
  • Fixed ladders on the fuel tanks near the launchpad.
0.19
  • New mesh for the launchpad and area (no launchtower anymore).
  • New mesh for the runway, with lights and sloping edges for rovers.
0.18
  • Terrain overhaul: Entire planet redo. Deserts, darker and greener grass, islands, darker ocean/water, snow capped mountains. Looks more realistic.
  • Several Easter Eggs added.
  • Airport added to island off of KSC coastline. (Not a launching point)
0.17
  • Improved atmosphere visuals.
0.15
0.14.2
  • Much more varied and taller terrain was added. Prior to this, some mountain ranges exceeded 600 m in height, but the tallest point was at an altitude of approximately 900 meters.
0.12
0.11
  • Terrain overhaul, oceans became wet.
0.10.1
  • Atmosphere extended from ~34,500 m to ~69,000 m.
0.7.3
  • Initial Release

Trivia

  • Kerbin's continents are derived from libnoise[3], a coherent noise generating library, though they have been increasingly modified with time.
  • Before 0.90 Kerbin was one of the few bodies with multiple Biomes. Following the 0.90 update all celestial bodies have biomes.
The biomes on Kerbin as of 0.90
  • The quote from the Kerbal Astronomical Society is true. As in real life and in Kerbal Space Program for an one-way interplanetary mission. half the delta v is expended on orbit.

Real-world comparison

Kerbin has approximately one-tenth the radius of Earth and 1/113th the mass.

See also

Notes

  1. ↑ “Some Major Orbit Types” uses that, the Wikipedia article mentions 0.74105, and “Orbital Parameters of a Molniya Orbit” uses 0.72.
  2. ↑ http://forum.kerbalspaceprogram.com/entry.php/247-A-Brave-New-World
  3. ↑ http://libnoise.sourceforge.net/examples/complexplanet/
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