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Vall as seen from orbit.
Moon of Jool
Orbital Characteristics
Semi-major axis 43 152 000 m [Note 1]
Apoapsis 43 152 000 m [Note 1]
Periapsis 43 152 000 m [Note 1]
Orbital eccentricity 0
Orbital inclination 0 °
Argument of periapsis 0 °
Longitude of the ascending node 0 °
Mean anomaly 0.9 rad (at 0s UT)
Sidereal orbital period 105 962 s
4 d 5 h 26 m 2.1 s
Synodic orbital period 106 069.5 s
Orbital velocity 2 559 m/s
Longest time eclipsed 4 706 s
Physical Characteristics
Equatorial radius 300 000 m
Equatorial circumference 1 884 956 m
Surface area 1.1309734×1012 m2
Mass 3.1087655×1021 kg
Standard gravitational parameter 2.0748150×1011 m3/s2
Density 27 487.522 kg/m3
Surface gravity 2.31 m/s2 (0.235 g)
Escape velocity 1 176.10 m/s
Sidereal rotation period 105 962.09 s
4 d 5 h 26 m 2.1 s
Sidereal rotational velocity 17.789 m/s
Synchronous orbit 3 593.20 km
Sphere of influence 2 406 401.4 m [Note 1]
Atmospheric Characteristics
Atmosphere present No
Scientific multiplier
Surface 12
Splashed N/A
Near space 9
Outer space 8
Recovery 8

  1. 1.0 1.1 1.2 1.3 The distances are given from the body's center, not from the surface (unlike ingame)

Vall is the second of the five natural satellites of Jool. Like the other large Joolian moons, Laythe and Tylo (of which Vall is the smallest), Vall is tidally locked to its parent. Synchronous orbits around Vall are not possible, as they would lie outside of its SOI, at a radius of 3,893,254 meters.

Vall occupies a comparable orbital position to Jupiter's moon, Europa. Also like Europa, it is remarkably crater-free. However, it has considerably greater surface relief, suggesting different internal structures or processes. Vall may be subject to less tidal heating, but still enough for the ice to have some plasticity and for small-scale cryovolcanism.

Though the bodies have topical similarities, landing on Vall and returning is significantly more challenging than a landing on the Mün, due to the former's higher gravity, more uneven terrain and distance from Kerbin.

According to former developer NovaSilisko, Vall was planned to be made more like Eeloo, with cracks in the ice and a more chaotic surface than in 0.20.2.[1]

In-game Description

KSP 1:

Vall was one of the last Moons of Jool to be discovered. Frustrated scientists kept attempting to wipe it off the lenses of their telescopes. Eventually after a rash of returned telescopes, Advanced Optics Co. finally decided to just tell them it was an actual object in the sky.

Kerbal Astronomical Society

KSP 2:

Vall, "The Frozen Wonderland," is the second moon orbiting Jool. The icy surface covers a liquid water ocean, which occasionally bubbles out of its many cryovolcanoes. Tidally locked to its parent planet, Vall's Jool-facing side is slightly warmed by radiation as it orbits. If you've wondered why some of the ice mountains can skewer your vessels and others seem smoother, now you know!


Vall has an icy surface dominated by hilly lowland areas separated by mountain ridges and which ranges in elevation from 0 to 7976 m. There are almost no completely level areas, making it hard to find good landing spots.

Vall has some circular mountain ridges which could be remnants of impact craters, but they are heavily eroded, hinting that Vall has some geological activity, presumably in the form of cryovolcanism.

The surface color ranges between white and light blue. When terrain scatters are activated, large boulders with contrast-rich black and white surface patterns can be found on the surface.


Vall has 9 biomes. It has mostly large Lowlands broken up by Midlands and Highlands with some high Mountains in between. There are four distinct Basins and Poles available as well.

Biome list

Vall In-game biome map as of 1.2
  • Poles
  • Highlands
  • Midlands
  • Lowlands
  • Mountains
  • Northeast Basin
  • Northwest Basin
  • Southern Basin
  • Southern Valleys

Reference Frames

Time warp Minimum Altitude
5× 24 500 m
10× 24 500 m
50× 24 500 m
100× 40 000 m
1 000× 60 000 m
10 000× 80 000 m
100 000× 100 000 m



  • According to the Tracking Station information on Vall, it was one of the last moons of Jool to be discovered. This was because the Kerbal astronomers mistook the icy moon for a smudge. After multiple failed attempts to get rid of the "smudge", they figured out it was, in fact, a moon.
  • If N-body simulation were used in the game, Vall would be slingshotted out of the Joolian system within a few days, due to the gravitational influences of nearby Laythe and Tylo, this implies that the spheres of influence are actual laws of physics in the KSP universe, not just for ease of processing.
  • One of the game loading screen phrases says "Sending Val to Vall" which refers to Valentina Kerman as Val.
  • Vall was possibly named after Vaal, a self aware computer from Star Trek.


  • Texture revamp
  • Added biomes
  • Added biomes
  • Initial Release


  1. Post in the forum by NovaSilisko