# Difference between revisions of "Duna"

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Duna is the fourth planet of the Kerbol star system. It is the Mars analog for Kerbal Space Program and is mostly red with polar icecaps. It has one natural satellite, the moon Ike. Due to Ike's size and proximity, Ike and Duna are tidally locked to each other.

## Topography

 A topographic map of Duna made with the ISA MapSat plugin Duna is a iron-rich planet which has greatly varying land altitude, the consequence of which is very difficult judgment of a safe landing position. Its mountainous ranges are a peril to landing craft, especially considering the thin atmosphere, where very little aerobraking can be done safely. It is important to slow one's ship down before coming into the atmosphere, to ensure a safe descent. There are several maria (large regions of dark soil) at exactly 0 meters altitude. These are excellent landing locations due to the their flatness and their low altitude, which allows for more aerobraking. Duna's poles are very expansive and are the result of a thin atmosphere. The central regions make a shape resembling Europe. Duna's surface contains anomolous features, including a rock face similar to the one seen in early satellite images of Mars.

## Atmosphere

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's at altitude 0 and is even less dense (relative to Kerbin) at higher 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:[1]

${\displaystyle p_{d}=0.2\ e^{-altitude/3000}}$

Parachutes work at lower efficiency than on Kerbin, making powered descent necessary when landing from orbit (unless your craft is a glider or just a pod with a parachute).

An ascent to Low Duna Orbit from the surface typically requires around 1500 to 2000 m/s in Delta-V, leaving you in a orbit at 42km altitude traveling at roughly 950 m/s.

The following table gives terminal velocities at different Duna altitudes. These are 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

## 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, a long-term orbit at this point is not possible, as it will eventually intersect Ike's SOI.

For a semi-synchronous orbit of ½ Duna day (9.025 hours or 32490 seconds) an orbit of 0.00 m above Duna is needed with a velocity of 0.00 m/s.

## Interplanetary Travel

From altitude orbit around Duna, the amount of delta-V needed to reach the orbits of other celestials is as follows:

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

 Warp 5x, 10x 50x 100x 1000x 10,000x 100,000x Minimum Altitude above atmosphere 60 km 100 km 300 km 600 km 800 km

## Changes

0.18
• Minor art pass
0.17
• Initial Release

## Trivia

• 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.
• Duna's name may be either a reference to its desert landscape or a shout-out to the Frank Herbert novel Dune.
• 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.

## Notes

1. A nuclear 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
2. http://forum.kerbalspaceprogram.com/showthread.php/6664-Mini-challenge-max-altitude-with-this-supplied-spacecraft?p=100912&viewfull=1#post100912