Difference between revisions of "Kerbin"

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'''Kerbin''' is the home planet of the [[Kerbal]]s, the location of the [[Kerbal Space Center|Space Center]], and the main focus of [[Kerbal Space Program]]. It is also the [[w:Earth|Earth]] analog for the game and has two [[moon]]s named '''[[Mun]]''' and '''[[Minmus]]'''.
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 [[delta-v|Δv]] of approximately 3400 m/s (vacuum), though the exact amount depends on the efficiency of the ascent profile and the aerodynamics of the launch vehicle and payload. The only planet that requires a higher Δv to attain orbit is [[Eve]]. Many interplanetary missions expend over half of their Δv in reaching Kerbin orbit. The energy required to escape a body from a given altitude is always exactly the square root of two times the kinetic energy of a circular orbit around the body at that height, leading one observer to remark:
{{Quote|If you can get your ship into orbit, you're halfway to anywhere.|Robert Heinlein|quoted on page 194 of ''A Step Farther Out'' by Jerry Pournelle}}
== In-game description ==
|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. <br><br> Reaching a stable orbit around Kerbin is one of the first things budding space programs strive for.  It is said that he who can get his ship into orbit is halfway to anywhere.
|[[Kerbal Astronomical Society]]}}
== Topography ==
[[File:Kerbin heightmap.jpg|thumb|left|Topographical representation of Kerbin's surface as of 0.18.2. Click for high resolution. by Zeroignite]]
[[File:TallestMountain_small.png|thumb|left|Kerbal at Kerbin's highest peak]]
Kerbin has a roughly equal distribution of surface liquid water and solid land, with polar icecaps and scattered deserts. Some of its mountains exceed 6&nbsp;km in height, with the tallest peak being 6764.1&nbsp;m in altitude at the coordinates 46°20'17" E 61°35'53" N. The lowest point is almost 1.4&nbsp;km deep and about 313° south-west of the Kerbal Space Center.
=== Craters ===
[[File:KerbinCraterElevation.jpg|thumb|left|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 [http://files.mundos-fantasticos.com/200000857-6eb2d6fab1/waves.jpg longitudinal], or P-wave [http://tpsearthspace12student.wikispaces.com/file/view/PwavesSwaves.jpg/113267379/PwavesSwaves.jpg earthquakes] that ensue.) Both are in excess of 100&nbsp;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 ==
[[File:KerbinBiomeMap.png|left|thumb|The biomes on Kerbin as of 0.90]]
Before 0.90 Kerbin was one of the few bodies with multiple [[Biome]]s, Kerbin was second only to the Mun in number of biomes it has. Following the 0.90 update all celestial bodies have biomes. [[Science]] [[Science#Activities|experiments]] can be performed at 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 destinct Northern and Southern Ice Shelf added
[[File:Kerbin biome 1800x900.png|thumb|left|Kerbin biome map as of 1.2]]
<span id="Planetary biome list"></span>
=== List of biomes ===
* Ice Caps
* Northern Ice Shelf
* Southern Ice Shelf
* Tundra
* Highlands
* Mountains
* Grasslands
* Deserts
* Badlands
* Shores
* Water
<span id="KSC location biome list"></span>
{{FlipBox|style=word-wrap: normal;margin: 0em 0em 0.5em; border-style: solid solid solid solid; padding: 0px; background-color: #FFFFFF; border-color:#aaaaaa; border-width:1px; width: 24em;
|title=KSC location biome list
* [[KSC]]
** [[Administration Facility|Administration]]
** [[Astronaut Complex]]
** Crawlerway
** [[Flag Pole]]
** [[Launch Pad|LaunchPad]]
** [[Mission Control]]
** [[Research and Development|R&D]]
*** R&D Central Building
*** R&D Corner Lab
*** R&D Main Building
*** R&D Observatory
*** R&D Side Lab
*** R&D Small Lab
*** R&D Tanks
*** R&D Wind Tunnel
** [[Runway]]
** [[Spaceplane Hangar|SPH]]
*** SPH Main Building
*** SPH Round Tank
*** SPH Tanks
*** SPH Water Tower
** [[Tracking Station]]
*** Tracking Station Dish East
*** Tracking Station Dish North
*** Tracking Station Dish South
*** Tracking Station Hub
** [[Vehicle Assembly Building|VAB]]
*** VAB Main Building
*** VAB Pod Memorial
*** VAB Round Tank
*** VAB SouthComplex
*** VAB Tanks
== Atmosphere ==
[[File:Kerbin_Atmosphere_T&P.png|thumbnail|left|Temperature and pressure of Kerbin's atmosphere as a function of altitude.]]
<!-- SPECULATION: Kerbin has an atmosphere of unknown composition, though Kerbin's plants and animals would not survive without O<sub>2</sub>, N<sub>2</sub>, and CO<sub>2</sub>. -->
Kerbin has a thick, warm [[atmosphere]] with a mass of approximately 4.7×10<sup>16</sup> 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 the only planet or moon with a breathable atmosphere.
The average [[w:Molecular_mass|molecular weight]] of Kerbin air is 28.9644 g/mol, and its [[w:Heat_capacity_ratio|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 [[w:Atmosphere_of_Earth|Earth's atmosphere]] (about 21%).
Like all other atmospheres in the game, Kerbin's atmosphere fades exponentially as altitude increases.  The [[w:Scale_height|scale height]] varies with altitude, which is a change from pre-1.0 [[Version_history|versions]] of the game.  The pressure-altitude profile is globally constant and independent of temperature.  The following table gives the atmospheric pressure at various altitudes above sea level.
{| class="wikitable"
! Altitude (m) !! Pressure (Pa) !! Pressure (atm)
| 0 || 101 325 || 1.000
| 2 500 || 69 015 || 0.681
| 5 000 || 45 625 || 0.450
| 7 500 || 29 126 || 0.287
| 10 000 || 17 933 || 0.177
| 15 000 || 6 722 || 0.066
| 20 000 || 2 546 || 0.025
| 25 000 || 989.0 || 0.010
| 30 000 || 401.3 || 0.004
| 40 000 || 78.99 || 0.001
| 50 000 || 15.56 || 0.000
| 60 000 || 2.382 || 0.000
| 70 000 || 0 || 0.000
Kerbin's atmosphere can be divided into three major layers, comparable to Earth's [[w:Troposphere|troposphere]], [[w:Stratosphere|stratosphere]] and [[w:Mesosphere|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 [[w:U.S._Standard_Atmosphere|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 [http://www.braeunig.us/space/atmmodel.htm#table4 equations of the USSA], where Kerbin's geometric altitude, z, is converted to Earth's geopotential altitude, h, using the following equation:
:h = 7963.75·z / (6371 + 1.25·z)
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.
[[Parachute]]s 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 engine]]s can operate in Kerbin's atmosphere. And, together with it's thickness, Kerbin's atmosphere is ideally suited for [[aircraft]] flight.
[[File:StationDocking.png|thumbnail|A modified Orbiter 1A prepares to dock with a space station.]]
== Orbits ==
[[File:Sputnik in Kerbin's orbit.png|thumbnail|left|A Stayputnik MK2 satellite]]
A [[synchronous orbit]] is achieved with a semi-major axis of {{OrbitAltitude|b=Kerbin|f=k|3=0}}. [[KEO|Kerbisynchronous Equatorial Orbit (KEO)]] has a circularly uniform altitude of {{OrbitAltitude|b=Kerbin|f=k}} and a speed of {{OrbitVelocity|b=Kerbin}}. From a 70&nbsp;km low equatorial orbit, the periapsis maneuver requires 676.5&nbsp;m/s and the apoapsis maneuver requires 434.9&nbsp;m/s. A syncronous [[w:Tundra orbit|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 [[w:semi-synchronous orbit|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 {{OrbitAltitude|b=Kerbin|f=k|pf=1/2}} with an orbital velocity of {{OrbitVelocity|b=Kerbin|pf=1/2}}. A semi-syncronous [[w:Molniya orbit|Molniya orbit]] with eccentricity of 0.742<ref>“[http://www.uwgb.edu/dutchs/AstronNotes/Orbits0.HTM Some Major Orbit Types]” uses that, [[w:Molniya orbit#References|the Wikipedia article]] mentions 0.74105, and “[http://www.eumetcal.org/euromet/english/satmet/s3220/s3220332.htm Orbital Parameters of a Molniya Orbit]” uses 0.72.</ref> and inclination of 63 degrees can not be achieved, because the periapsis would be 36&nbsp;km below the ground. The highest eccentricity of a semi-synchronous orbit with a periapsis of 70&nbsp;km is 0.693<!---389102957193457747187874683092468355009655955115825698569= (1585.18 + 600-670)/(1585.18 + 600)--> with an apoapsis of 3100.36<!-- (1585.18+600)*2-670-600 -->&nbsp;km.
The [[w:Hill sphere|Hill sphere]] (the radius around the planet at which moons are gravitationally stable) of Kerbin is 136 185&nbsp;km, or roughly 227 Kerbin radii.
<div style="clear:left;"></div>
== Delta-V Requirements ==
From the lowest stable orbit around Kerbin (70&nbsp;km), the nominal amount of delta-V needed to reach other destinations is:
{| class="wikitable"
| [[Mun]]
| ~860&nbsp;m/s
| [[Minmus]]
| ~930&nbsp;m/s
| [[Eve]]
| ~1033&nbsp;m/s
| [[Duna]]
| ~1060&nbsp;m/s
| [[KEO|Geostationary Orbit]]
| ~1120&nbsp;m/s
| [[Moho]]
| ~1676&nbsp;m/s
| [[Jool]]
| ~1915&nbsp;m/s
| [[Eeloo]]
| ~2100&nbsp;m/s
| [[Kerbol]] escape
| ~2740&nbsp;m/s
== Reference frames ==
== Gallery ==
Kerbin ISA Topo 0 21.jpg  |Topographical map of Kerbin as of {{version|0.21}}
Kerbin map from 0.14.jpg  | A projection map of Kerbin, as of [[0.14.1]] and before (including the old demo).
Kerbin color.png          | An accurate full-colour projection map of Kerbin as of [[0.14.2]] to [[0.17.1]]
KerbinDeltaVMap.png        | A map displaying the delta V needed from/to Kerbin
Kerbin_mun_minmus.jpg | Kerbin, Mun and Minmus.
Kerbin,_Mun,_and_Minmus.jpeg | 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.
kerbin map 800.gif | A topographic heightmap of Kerbin made with the ISA MapSat plugin
Kerbinmun500550km.png      | Kerbin and the Mun, barely visible from ~500,550,000m
Kerbin ISA Topo.png | Topographical image of Kerbin '''from 0.17.1'''. The terrain is slightly different in the latest version.<ref>http://forum.kerbalspaceprogram.com/entry.php/247-A-Brave-New-World</ref>
Kerbin r0 1.png | An unmanned probe on escape trajectory, flying past Kerbin, Mun and Minmus
KerbalPolar1.png | Kerbin's North Pole
Solar eclipse in LKO.jpg | A solar eclipse from low Kerbin orbit (LKO).
|description=Easter Eggs Are Shown
Kermmunist_Launch_Site.png | The second launch site (currently unused).
KEasterEgg.png | Kerbin from above with the Runway Easter Egg
File:Crashed Polar UFO.png| A Crashed UFO on Kerbin's northern ice cap.
== Changes ==
* Added biomes.
* Mass reduced to compensate for g0 and G changes.
* Kerbin actually spun up to have a 6 h synodic day.
* Updated biomes.
*Biomes added.
*Terrain revised to produce more detailed and interesting landforms.
*Fixed ladders on the fuel tanks near the launchpad.
*New mesh for the launchpad and area (no launchtower anymore).
*New mesh for the runway, with lights and sloping edges for rovers.
*Terrain overhaul: Entire planet redo. Deserts, darker and greener grass, islands, darker ocean/water, snow capped mountains. Looks more realistic.
*Several [[List of easter eggs|Easter Eggs]] added.
*Airport added to island off of KSC coastline. (Not a launching point)
* Improved atmosphere visuals. 
* [[Minmus]] added.
* Much more varied and taller terrain added. Prior to this, some mountain ranges exceeded 600 m in height, but the tallest point was at an altitude of approximately 900 m.
* [[Mun]] added.
* Terrain overhaul, oceans became wet.
* Atmosphere extended from ~34,500 m to ~69,000 m.
* Initial Release
== Trivia ==
Kerbin's continents are derived from libnoise,<ref>http://libnoise.sourceforge.net/examples/complexplanet/</ref> a coherent noise generating library, though they have been increasingly modified with time.
=== Real-world comparison ===
Kerbin has approximately 1/113<sup>th</sup> the mass and a 1/10<sup>th</sup> the radius of Earth.
== Notes ==
<references />
{{Celestial Bodies}}

Revision as of 18:11, 17 March 2017