Difference between revisions of "Duna"
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{{:Duna/Data}} | {{:Duna/Data}} | ||
| − | '''Duna''' is the fourth planet of the [[Kerbol System|Kerbol star system]]. | + | '''Duna''' is the fourth planet of the [[Kerbol System|Kerbol star system]]. As is the [[w:Mars|Mars]] analog for Kerbal Space Program, it is mostly red with polar icecaps and has one natural satellite, the [[moon]] '''[[Ike]]'''. Ike's size and proximity tidally locks it and Duna to each other. |
| − | With proper aerobraking, a round trip from [[Kerbin]] to Duna's orbit and back requires roughly 1700 m/s of [[Terminology#Physics|delta-v]], less than a round trip to any other planet. Duna is often the easiest planet to | + | With proper aerobraking, a round trip from [[Kerbin]] to Duna's orbit and back requires roughly 1700 m/s of [[Terminology#Physics|delta-v]], less than a round trip to any other planet. Duna is often the easiest planet to encounter because its orbital inclination is low. |
== Topography == | == Topography == | ||
[[File:Duna Topo ISA 3200x1600 compressed.png|thumb|left|A topographic map of Duna made with the ISA MapSat plugin]] | [[File:Duna Topo ISA 3200x1600 compressed.png|thumb|left|A topographic map of Duna made with the ISA MapSat plugin]] | ||
| − | Duna's terrain ranges in altitude from 124 to 8264 meters. Its mountainous ranges are a peril to landing craft, especially considering the thin atmosphere, | + | Duna's terrain ranges in altitude from 124 to 8264 meters. Its mountainous ranges are a peril to landing craft, especially considering the thin atmosphere, which permits very little safe aerobraking and causes Duna's expansive, icy poles. |
Duna has several craters, but they appear quite eroded, presumably from wind. | Duna has several craters, but they appear quite eroded, presumably from wind. | ||
| − | + | Several [[w:Lunar maria|maria]] (large regions of dark soil) are at exactly 0 meters altitude {{deprecated}}. Their flatness and low altitude allow for more aerobraking and make them easy but boring landing locations. These may have been lakes when the planet may have had liquid on it's surface in the past. | |
Duna's surface contains [[List of easter eggs#Duna|anomolous features]]. | Duna's surface contains [[List of easter eggs#Duna|anomolous features]]. | ||
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[[File:Atmosphere_kerbin_duna.png|thumb|left|A comparison of the atmospheres of Duna and Kerbin]] | [[File:Atmosphere_kerbin_duna.png|thumb|left|A comparison of the atmospheres of Duna and Kerbin]] | ||
| − | Duna's [[atmosphere]] begins at 41,446 m. It is only 20% as dense as [[Kerbin|Kerbin's]] at altitude 0 and is even less dense (relative to Kerbin) at higher altitudes | + | Duna's [[atmosphere]] begins at 41,446 m. It is only 20% as dense as [[Kerbin|Kerbin's]] at altitude 0 and is even less dense (relative to Kerbin) at higher altitudes: at Duna's highest points, atmospheric density is only 21% of that at altitude 0. (For comparison, on Kerbin, the atmosphere at the highest peaks is 45% as thick as at sea level.) This low density will cause parachutes to semi-deploy much lower, just over 10km for the [[Mk25 Parachute]], and just under 9km for all the other parachutes. |
<div style="clear:left;"></div> | <div style="clear:left;"></div> | ||
=== Landing === | === Landing === | ||
| − | + | [[Aerobraking]] can save fuel by reducing orbital and surface velocity greatly. An aerobraking maneuver should maximize time spent in the atmosphere by entering at a shallow angle and aiming for a landing location in a low-lying area. | |
Like all atmospheres in the game, Duna's atmosphere fades exponentially with increasing altitude (with a scale height of 3000 m). In general, the atmospheric pressure on Duna at an altitude expressed in meters is:<ref>A [[LV-N Atomic Rocket Engine]] has a specific impulse of 220 in 1 atm, 800 in vacuum, and the following at various Duna altitudes: | Like all atmospheres in the game, Duna's atmosphere fades exponentially with increasing altitude (with a scale height of 3000 m). In general, the atmospheric pressure on Duna at an altitude expressed in meters is:<ref>A [[LV-N Atomic Rocket Engine]] has a specific impulse of 220 in 1 atm, 800 in vacuum, and the following at various Duna altitudes: | ||
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: <math>p_d = 0.2\ e^{-altitude/3000}</math> | : <math>p_d = 0.2\ e^{-altitude/3000}</math> | ||
| − | + | The low efficiency of parachutes on Duna necessitates powered descent (unless you have enough drag/parachutes). | |
[[File:Duna colony.png|thumb|A nine Kerbal colony on Duna]] | [[File:Duna colony.png|thumb|A nine Kerbal colony on Duna]] | ||
=== Flying === | === Flying === | ||
| − | + | Below 5 km Duna's atmospher is thick enough to allow wings to generate enough lift for aerodynamic flight. Jet engines don't work for want of oxygen, but other propulsion methods work well. Performing a horizontal landing with a plane is also possible. | |
=== Starting === | === Starting === | ||
| − | An ascent to Low Duna Orbit from the surface typically requires around 1500 to 2000 m/s in Delta-V | + | An ascent to Low Duna Orbit from the surface typically requires around 1500 to 2000 m/s in Delta-V to reach a 42km altitude traveling at roughly 950 m/s. |
| − | The following table gives terminal velocities at different Duna altitudes | + | The following table gives terminal velocities at different Duna altitudes, which also the velocities at which a ship should travel for a fuel-optimal ascent from Duna, given the game's model of atmospheric drag.<ref>http://forum.kerbalspaceprogram.com/showthread.php/6664-Mini-challenge-max-altitude-with-this-supplied-spacecraft?p=100912&viewfull=1#post100912</ref> |
{| class="wikitable" | {| class="wikitable" | ||
|- | |- | ||
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== Observation of Ike == | == Observation of Ike == | ||
| − | Ike's orbit keeps it directly above a short range of | + | Ike's orbit keeps it directly above a short range of Dunar longitudes. The average Duna longitude that Ike tends to stay directly above (at the [[w:Zenith|Zenith]]) is 6 degrees east, but the eccentricity of Ike's orbit causes the exact longitude to oscillate between about 2 degrees and 10 degrees east and makes Ike appear to grow slightly larger and smaller to an observer on the surface of Duna. The latitude at which Ike is in the Zenith also oscillates between 0.2 degrees south and 0.2 degrees north due to Ike's orbital inclination, making Ike appear to rotate upwards and downwards as viewed from the surface, but due to the extremely small orbital inclination, this effect is nearly imperceptible. These phenomena together are known as [[w:libration|libration]]. The oscillation in Ike's position above the horizon allows areas from 88°W to 80°W and 92°E to 100°E on Duna to observe Ike rise and set at least partially across the horizon, as can any areas north of 89.8°N or south of 89.8°S. |
== Interplanetary Travel == | == Interplanetary Travel == | ||
| − | From altitude orbit around Duna, the | + | From altitude orbit around Duna, the delta-V needed to reach the orbits of other celestials is: |
{| class="wikitable" | {| class="wikitable" | ||
Revision as of 00:02, 28 August 2013
Duna is the fourth planet of the Kerbol star system. As is the Mars analog for Kerbal Space Program, it is mostly red with polar icecaps and has one natural satellite, the moon Ike. Ike's size and proximity tidally locks it and Duna to each other.
With proper aerobraking, a round trip from Kerbin to Duna's orbit and back requires roughly 1700 m/s of delta-v, less than a round trip to any other planet. Duna is often the easiest planet to encounter because its orbital inclination is low.
Contents
Topography
Duna's terrain ranges in altitude from 124 to 8264 meters. Its mountainous ranges are a peril to landing craft, especially considering the thin atmosphere, which permits very little safe aerobraking and causes Duna's expansive, icy poles.
Duna has several craters, but they appear quite eroded, presumably from wind.
Several maria (large regions of dark soil) are at exactly 0 meters altitude (deprecated). Their flatness and low altitude allow for more aerobraking and make them easy but boring landing locations. These may have been lakes when the planet may have had liquid on it's surface in the past.
Duna's surface contains anomolous features.
Atmosphere
Duna's atmosphere begins at 41,446 m. It is only 20% as dense as Kerbin's at altitude 0 and is even less dense (relative to Kerbin) at higher altitudes: at Duna's highest points, atmospheric density is only 21% of that at altitude 0. (For comparison, on Kerbin, the atmosphere at the highest peaks is 45% as thick as at sea level.) This low density will cause parachutes to semi-deploy much lower, just over 10km for the Mk25 Parachute, and just under 9km for all the other parachutes.
Landing
Aerobraking can save fuel by reducing orbital and surface velocity greatly. An aerobraking maneuver should maximize time spent in the atmosphere by entering at a shallow angle and aiming for a landing location in a low-lying area.
Like all atmospheres in the game, Duna's atmosphere fades exponentially with increasing altitude (with a scale height of 3000 m). In general, the atmospheric pressure on Duna at an altitude expressed in meters is:[1]
The low efficiency of parachutes on Duna necessitates powered descent (unless you have enough drag/parachutes).
Flying
Below 5 km Duna's atmospher is thick enough to allow wings to generate enough lift for aerodynamic flight. Jet engines don't work for want of oxygen, but other propulsion methods work well. Performing a horizontal landing with a plane is also possible.
Starting
An ascent to Low Duna Orbit from the surface typically requires around 1500 to 2000 m/s in Delta-V to reach a 42km altitude traveling at roughly 950 m/s.
The following table gives terminal velocities at different Duna altitudes, which also the velocities at which a ship should travel for a fuel-optimal ascent from Duna, given the game's model of atmospheric drag.[2]
| Altitude (m) | Velocity (m/s) |
|---|---|
| 0 | 212 |
| 1000 | 231 |
| 2000 | 252 |
| 3000 | 274 |
| 5000 | 324 |
| 8000 | 418 |
| 10000 | 495 |
| 13000 | 638 |
| 15000 | 756 |
| 20000 | 1.16×103 |
Tracking Station Info
Also known as the red dot that you can see if you squint really hard, Duna has long been a wonder to Kerbalkind. The planet has been held in much awe, due to its striking red color and stark contrast to the color green.
Orbital Statistics
The geosynchronous orbit of Duna is at an altitude of 0.00 m above Duna. The speed of the satellite is 0.00 m/s and it has an orbital period resonating with 1 Duna day (18.2 hours or 65517.859375 seconds). However, this is the same altitude at which Ike orbits, so unless a ship's orbit is perfectly precise, it will eventually be captured by Ike.
For a semi-synchronous orbit of ½ Duna day (9.1 hours or 32758.9295 seconds) an orbit of 0.00 m above Duna is needed with a velocity of 0.00 m/s.
Observation of Ike
Ike's orbit keeps it directly above a short range of Dunar longitudes. The average Duna longitude that Ike tends to stay directly above (at the Zenith) is 6 degrees east, but the eccentricity of Ike's orbit causes the exact longitude to oscillate between about 2 degrees and 10 degrees east and makes Ike appear to grow slightly larger and smaller to an observer on the surface of Duna. The latitude at which Ike is in the Zenith also oscillates between 0.2 degrees south and 0.2 degrees north due to Ike's orbital inclination, making Ike appear to rotate upwards and downwards as viewed from the surface, but due to the extremely small orbital inclination, this effect is nearly imperceptible. These phenomena together are known as libration. The oscillation in Ike's position above the horizon allows areas from 88°W to 80°W and 92°E to 100°E on Duna to observe Ike rise and set at least partially across the horizon, as can any areas north of 89.8°N or south of 89.8°S.
Interplanetary Travel
From altitude orbit around Duna, the delta-V needed to reach the orbits of other celestials is:
| Body | Delta-V | |
|---|---|---|
| Ike | ~300 m/s | |
| Kerbin | ~620 m/s | |
| Dres | ~820 m/s | |
| Eve | ~1080 m/s | |
| Jool | ~1350 m/s | |
| Eeloo | ~1580 m/s | |
| Moho | ~2100 m/s | |
Reference Frames
| Time warp | Minimum Altitude |
|---|---|
| 1× | Any |
| 5× | 50 000 m (above the atmosphere) |
| 10× | 50 000 m (above the atmosphere) |
| 50× | 60 000 m |
| 100× | 100 000 m |
| 1 000× | 300 000 m |
| 10 000× | 600 000 m |
| 100 000× | 800 000 m |
Gallery
Parachute descent down to Duna surface.
ISA satellite in orbit over Duna being used to map the planet surface.
Duna's surface at Dawn.
Duna and Ike.
A topographic height map of Duna made with the ISA MapSat plugin
A color map of Duna
Duna at sunrise
A rover at the edge of one of the "sinkholes"
Bill, his capsule, a flag, and Ike are all in this picture
Changes
- Art Pass
- Minor art pass
- Initial Release
Trivia
- Duna's name may be either a reference to its desert landscape or a shout-out to the Frank Herbert novel Dune.
- The low-lying areas near Duna's equator make a shape resembling Europe.
- On the surface of Duna, there is a large monument carved in the likeness of a Kerbal face, alluding to the infamous "Face of Mars" discovered in the Cydonia Mensae region of Mars during the 1970's.
- Buried deep under the surface, there is a small camera, similar to the design on the Pathfinder rover.
- One anomalous feature on Duna is a small, pyramid-like hill emitting an SSTV signal. When decrypted, it shows a diagram-like image of three figures standing next to the hill itself, implying that Duna was once inhabited or visited before.
Notes
- ↑ A LV-N Atomic Rocket Engine has a specific impulse of 220 in 1 atm, 800 in vacuum, and the following at various Duna altitudes:
altitude (m) 2 100 300 500 1460 2420 3000 4272 5000 10000 specific impulse 684.1 687.8 695.1 701.8 728.7 748.2 757.3 772.1 778.1 795.9 - ↑ http://forum.kerbalspaceprogram.com/showthread.php/6664-Mini-challenge-max-altitude-with-this-supplied-spacecraft?p=100912&viewfull=1#post100912
