Unimplemented Content

The following is a list of content that was stated at one point by a developer to be planned to be added to Kerbal Space Program, but was never implemented into the game.

New Celestials

Xubol

A near-molten ball of salt and sand, Xubol was to be the first planet of the Kerbol System.^[1]

Radius: 200 kilometers
Rotation period: 2.5 hours
Atmospheric density: 0.005 kb (kb = Kerbal Bars, equal to Kerbin's atmospheric pressure at sea level)
Surface gravity: 0.2 g
Semimajor Axis: 2,243,970 kilometers
Inclination: n/a
Eccentricity: 0.425

Faz and Jall

Planned moons of Eve.

Faz was to have a 30km radius and 3,000km semimajor axis.
Jall was to have a 200km radius and 8,000km semimajor axis.

Rupa

Rupa, a planned moon of Kerbin with a 60km radius and 30,500km semimajor axis, was revised to become Minmus.

Meander

A brilliant green gas planet, worshiped in years past as the god which created Kerbal-kind. Revised to become Jool.

Radius: 2,700 kilometers
Rotation period: 8.5 hours
Atmospheric density: 15.0 kb (at 50 km down)
Semimajor Axis: 19,447,740 kilometers
Inclination: n/a
Eccentricity: n/a

Moons:

Haqua (150km, 6,350km)
Egar: The second-largest moon of Meander, Egar is an interesting contrast. Half icy wasteland, half desert - enormous polar ice caps dominate this moon. Revised to become Duna.
- Radius: 350 kilometers
- Rotation period: Tidally locked
- Atmospheric density: 0.025 kb
- Surface gravity: 0.7 g
- Semimajor Axis: 13,500 kilometers
- Inclination: n/a
- Eccentricity: n/a
Lumowan (400km, 25,800km)
Minor moons: 20+

Toshakona Belt

A ring of debris large and small stretching from just outside Meander's orbit to just inside that of Juniper.

Sothebin

Upon discovery it was touted as a 'Second Kerbin' - but that frenzy died down quickly after discover that the dark patches on its surface were dried basaltic lava, not oceans.

Radius: 720 kilometers
Rotation period: 9 hours
Atmospheric density: 0.8 kb
Semimajor Axis: 28,423,620 kilometers
Inclination: 0.35 °
Eccentricity: 0.09
Surface gravity: 3.4 g

Juni

The largest of the planets, Juni was also to boast the largest ring system and most moons.

Radius: 5,800 kilometers
Rotation period: 9 hours
Atmospheric density: 80 kb (at 50 km down)
Semimajor Axis: 28,423,620 kilometers
Inclination: 0.35 °
Eccentricity: 0.09

Moons:

Gax (230km, 34,400km)
Tiberius
Minor moons: 30+
Junimu: The largest known moon, and the only one with a ring system of its own, composed mostly of material stolen from the main rings of Juni.
- Radius: 600 kilometers
- Rotation period: 4.5 hours
- Atmospheric density: 0.8 kb
- Surface gravity: 0.8 g
- Semimajor Axis: 59,000 kilometers
- Inclination: n/a
- Eccentricity: n/a

Mandrake & Rutherford

Mandrake and Rutherford were to be two brilliant blue gas planets orbiting one another, named for their siamese twin discoverer(s), Mandrake & Rutherford Kerman. How they formed is unknown, as is how long this configuration will last.

Radius: 3,100 kilometers & 2,900 kilometers respectively
Rotation period: Tidally locked
Atmospheric density: 20 kb (at 50 km down)
Orbital parameters (around Kerbol):
- Semimajor Axis: 67,663,175 kilometers
- Inclination: 1.5 °
- Eccentricity: 0.015
Orbital parameters (around the other planet):
- Semimajor Axis: 38,500 kilometers
- Inclination: n/a
- Eccentricity: n/a

Harvest

A reddish-brown miniplanet sharing Kerbin's orbit, occupying its L4 Lagrange Point.

Radius: 80 kilometers
Rotation period: 5 hours
Atmospheric density: n/a
Surface gravity: 0.02 g
Semimajor Axis: 13,680,255 kilometers
Inclination: n/a
Eccentricity: n/a

Ralph

An icy body, situated between Meander and Juniper.

Radius: 110 kilometers
Rotation period: 24 hours
Atmospheric density: n/a
Surface gravity: 0.12 g
Semimajor Axis: 37,399,500 kilometers
Inclination: 8.6 °
Eccentricity: 0.15

Moons:

Ralph Jr.(10km, 550km)

Gas planet 2

~50% larger than Jool, with rings.^[2]

Eeloo: Relocated to orbit GP2, now with large geysers that can knock ships around.
Daphy: Unusually smooth and round ball of fluff. An asteroid which has accumulated material from the rings, practically no gravity.
Potatus: Small moon with relatively high inclination relative to GP2's equator. Composed of ices surrounding a highly dense core. Very rapid rotation (21 minutes) causes it to be stretched into an oblate spheroid.
Fonso: Largest moon, ~300 km radius. Very mountainous, with a thick atmosphere that only extends partway up the mountains (the mountain peaks are in vacuum, while the proper surface is at two atmospheres).
Tiny moons: Same case as Jool.

Gas planet 3

Perhaps not an actual gas planet, could be a 2000km rocky planet with a thick atmosphere, with 6g and 30 atmospheres of pressure at the surface.

Possible moon with rings, would have to be diffuse rings as well as recent, fully-formed rings wouldn't last long in that position.

Mez

Super-Kerbin with rapid rotation period, somewhat lens-shaped as a result.

Thick atmosphere
Gravity at poles approaches 10-20g, gravity at equator only ~0.05g.
Scale height of atmosphere varies accordingly, and grows very diffuse and stretched around the equator.

Miscellaneous

Low-density belt of vulcanoid asteroids below the orbit of Moho.^[3]
Asteroids discoverable in the actual asteroid belt, along with a significant quantify of larger asteroids.
Additional gas planets beyond the third one.
Extra bodies with analogues of most real-world dwarf planets (especially Sedna).

Changes to Existing Celestials

Eve

Inclination reduced to make an easier early-game interplanetary target.
Hotter and generally more angry atmosphere on Eve.
Not as purple.
Perpetual clouds and heavy haze, thunder ambiance, flashes of lightning and a surface dark enough to require lights to see properly (except when the lightning is going).

Kerbin

Small amounts of eccentricity and inclination.

Mun

More realistic crater distribution in both size and location.
Tycho crater ripoff with properly shaped solid-black monolith.

Duna

More, flatter lowlands, more obvious ancient water-carved features.
More irregular ice caps with "super cool" features.
An additional asteroidal moon, far beyond Ike, if the systems allowed it it would have irregular rotation like Pluto's small moons are expected to (due to the odd dynamics of a binary planet system).

Ike

Return of the magic boulder.
Craters and a more moon-like heightmap.

Jool

Actually the second-smallest gas giant, with unusually large moons. All other gas giants would have objects smaller than or comparable to Moho.

Re-arrangement of major moons to be more widely spaced and similar to Saturn's layout of moons.
150% its original size, with enlarged moon orbits as well.
Not so green, perhaps green bands instead, which when sampled yield algae.
Oblateness similar to that of Saturn's or Jupiter's (would require reworking of how atmospheres are handled).
More tiny moons: Just a bunch of small moonlets, at least 20. Probably would be nameable by the player or given designations (ex. J-17 for the 17th moon of Jool discovered).

Laythe

Very volcanic because of its proximity and the tidal forces from the other moons. Still oceans of water, but now with actual active volcanos with lava lakes (that destroy things).
Smaller, Duna sized.
Mostly cloud covered.
No ice caps (hot greenhouse atmosphere would destroy them easily).
Faint torus of gas along its orbit from escaping atmosphere (not enough to affect ships, but enough to catch the light, as in Saturn's E ring (possibly enough to change orbits using aerodynamic surfaces).

Vall

More like eeloo, with large cracks in the ice and a more chaotic surface.
Smaller, Mun sized.

Tylo

Perhaps turned into a highly-contrasting body like Iapetus.
Smaller, slightly below Duna sized.
Two-thirds-gee surface gravity (High for a body of that size, so perhaps a dense iron core surrounded by ices; a body from the inner solar system that was ejected and then captured by Jool).
Ice geysers + resulting atmosphere.
Second faint gas torus.

Eeloo

Surface like Pluto with "flowy stuff".
Small blob of a moon.

Technical advances

Functional atmospheres for non-spherical bodies.
Proper altitude detection for non-spherical bodies.
Non-spherical atmosphere rendering.
Gas torus rendering.
Dynamic loading/unloading of planet surface maps to keep memory usage sane (or just 64-bit and deal with the inefficiency).
Ambient sound system for planets.
Irregular planetary rotation (optional, for Duna's minimoon).
Clouds.