Eeloo (OPM)
Eeloo orbit
Eeloo (OPM) as seen from orbit.
Moon of Sarnus
Orbital Characteristics
Semi-major axis 19 105 978 m [Note 1]
Apoapsis 19 170 938 m [Note 1]
Periapsis 19 041 018 m [Note 1]
Orbital eccentricity 0.003
Orbital inclination 2.3 °
Argument of periapsis 260 °
Longitude of the ascending node 55 °
Mean anomaly 3.14 rad (at 0s UT)
Sidereal orbital period 57 915 s
2 d 4 h 5 m 14.8 s
Synodic orbital period 57927.7 s
Orbital Velocity 2 066 to 2 080 m/s
Longest Time Eclipsed 5200 s
Physical Characteristics
Equatorial radius 210 000 m
Equatorial Circumference 1 319 469 m
Surface area 5.5417694×1011 m2
Mass 1.1149224×1021 kg
Standard gravitational parameter 7.4410815×1010 m3/s2
Density 28 740.754 kg/m3
Surface gravity 1.69 m/s2 (0.172 g)
Escape velocity 841.83 m/s
Sidereal rotation period 57 914.784 s
2 d 4 h 5 m 14.8 s
Sidereal rotational velocity 22.783 m/s
Synchronous orbit 1 639.06 km
Sphere of influence 1 159 066.2 m [Note 1]
Atmospheric Characteristics
Atmosphere present × No
Scientific multiplier
Surface 11
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 bodies center not surface (unlike ingame)

Eeloo is the third moon of Sarnus and was originally the seventh (and last) celestial body in the game. The Outer Planets Mod changes the orbit of the once-dwarf-planet into a tidally-locked moon of Sarnus, making it an analog for Enceladus. It is any icy world marked by dark streaks and fissures in the surface.

As with the rest of Sarnus' moons, Eeloo's relatively large distance from Kerbol reduces solar panel output to as little as under 1.06% of that at Kerbin. Bringing an alternate power source (e.g. RTGs) is recommended.

In-Game Description

Discovered at the same time as Plock, the square heads in charge of cataloging the astronomical discoveries mixed up the records of two celestial bodies, leading to years of one being confused for the other. The surface of Eeloo is covered in brown scratches, which could be the result of cryovolcanic activity. This might mean that the moons harbors a liquid ocean beneath its frozen crust.

Kerbal Astronomical Society


The surface of Eeloo is relatively smooth and covered in gray-white ice, with deep canyons exposing the brownish rock below. There are few large craters, but the surface is peppered with smaller procedural impact craters. Its highest points are near the equator and are almost 3.9 km high, while the lower areas can go lower than sea level.

Eeloo's surface lacks ground scatter, suggesting the ice on the surface is subject to erosion of some sort.

It originally had an atmosphere early in its development as a stock body, but was been removed because the renderer for it doesn't work on bodies smaller than about Duna's size.

Subsurface Ocean

It is widely believed that there is a liquid ocean underneath the moon's icy surface. Being tidally locked to a gas giant, the interior of the moon could be internally warmed by the tidal forces but sealed from radioactivity and the elements of space from its icy crust - which would allow the interior of the moon to remain a liquid.


The composition of Eeloo is widely believed to be that of water ice, however recent irradiance scans implicate a surface that is more reflective than water ice. This may indicate that at least the surface of the moon may be coated in a different material, if not the liquid ocean underneath as well.

One can estimate the composition of the moon using the average density. This gives a possible interior structure: An ice crust and subsurface ocean 21 km thick - it is still unknown how thick the ice sheet is - estimates range from 1 to 18 km thick; a rocky "mantle" around 150 km thick, and an iron core with a radius of 37.8 km.


Eeloo has a total of 11 biomes.

Biome list

Eeloo (OPM) Biome Map

Eeloo (OPM) biome map

  • Poles
  • Northern Glaciers
  • Lowlands
  • Highlands
  • Ice Canyons
  • Craters
  • Midlands
  • Fragipan
  • Babbage Patch
  • Southern Glaciers
  • Mu Glacier


Being a moon of Sarnus, its faraway orbit, in addition to its low gravity, make encounters challenging. Its distance from Kerbin also tends to make missions very lengthy.

A synchronous orbit around Eeloo is not possible as it lies just outside Eeloo's sphere of influence, as is common with tidally locked bodies.

Reference Frames

Warp Minimum Altitude
5× 3 938 m
10× 7 875 m
50× 15 750 m
100× 31 500 m
1 000× 63 000 m
10 000× 126 000 m
100 000× 252 000 m