View source for Celestial Bodies

<i>This page discusses the game mechanics for celestial bodies. For a list of all space bodies in Terra Invicta, as well as their stats, see [[Space Body List]] instead.</i>

'''Celestial Bodies''' are naturally occurring significant gravitational masses, representing the major locations of Terra Invicta's [[Solar System]]. They are the primary targets for the industrialization of space via [[Factions|human]] and [[Aliens|alien]] [[Habs|infrastructure]] ([[Solar System#Lagrange Points|Lagrange points]] being the exception).

The number of bodies depends on the [[Game Options#Solar system|System setup]] at the beginning of the campaign, but objects are always present in the game up to a distance of 50 Astronomical Units from the Sun (up to the Kuiper Belts)

[[File:Celestial_Bodies_1.png|upright=0.75|framed|right|Saturn and its satellites, as seen at the beginning of a campaign.]]

== Body types and Composition ==
With the exception of [[Sol|the Sun]], there are six main categories of celestial bodies modeled by the game: planets, dwarf planets, planetary moons, ateroidal moons, asteroids, and comets. These are subdivided into astrological classifications that form the title of a selected body (e.g. "terrestrial planet", "gas giant", "centaur").

Celestial bodies can have varying compositions between campaigns. The resource extraction potential is [[#Resource Formulas|calculated]] separately for each body and can differ drastically between playthroughs, based on resource rolls. The specific resource availability of a body is only revealed after [[Solar System#Prospecting|prospecting]], and can change as [[events]] are triggered by the game.

Determining the exact resources available requires either a probe, or a [[Spaceships|ship]] with a [[Mobile Space Science Lab]] to perform a survey operation. This prospecting data can also be acquired from other [[Factions]] by using the {{MissionIcon|Turn}}[[Turn Councilor]] mission or by forming an [[Factions#Trade_Negotiations|Intel Sharing Agreement]].

''*Tip: If you want to send many probes there is a one-click option in the Intel -> Solar System tab.''

== Orbits and Sites ==
Every celestial body has at least one [[Solar System#Orbits|orbit]]; planets and planetary moons also have [[Solar System#Lagrange Points|Lagrange points]] – these provide locations where [[Habs#Stations|stations]] can be constructed. Excluding [[Venus]] and the gas giants, almost every celestial body can have up to 25 surface locations (sites) where [[Habs#Bases|bases]] can be built.

A higher number of base sites and station orbits are more likely to be found on and around larger bodies, which are also more likely to support higher tier habitats ({{bodyIcon|Tier 1}}, {{bodyIcon|Tier 2}}, {{bodyIcon|Tier 3}}). In terms of orbits, the situation is more varied.

Low and high orbits are found on larger celestial bodies with asteroids and asteroidal moons often have "parking" orbits instead. Larger bodies can also support additional orbits, such as: Inclined, Medium, Intermediate, Extreme and Synchronous. The Earth has three unique orbits: Tiangong Orbit, ISS Orbit and Low Orbit 2. The altitude, gravitational pull, and the number of possible stations allowed in each orbit is unique to each body (though station number caps are typically 1 for asteroids and inclined orbits, 4 for dwarf planets and some moons, and 8 for the rest). [[Solar System#Lagrange Points|Lagrange points]] always have 1 orbit allowing a single station.

Low and parking orbits are also considered "interface" orbits (denoted by a body icon next to them), which allows several interactions through the use of specific [[Habs|hab]] and [[Spaceships|ship]] modules. As well as having by far the largest variety of possible interface orbit options, Earth also offers more than twice as many stations in interface orbits than other planets; "Low Earth orbit 2" doubles the default to 16, and the Tiangong and ISS orbits offer two more (uniquely inclined) low interface orbits. The latter two correspond to those of the real world International Space Station and Tiangong Station, and each allows for one additional station in an Earth interface orbit.

== Resources and Mining ==
The five basic space [[Resources|resources]] ({{icon|water|bgcolor=DarkSlateGray}} Water, {{icon|volatiles|bgcolor=DarkSlateGray}} Volatiles, {{icon|metals|bgcolor=DarkSlateGray}} Metals, {{icon|nobles|bgcolor=DarkSlateGray}} Nobles, and {{icon|fissiles|bgcolor=DarkSlateGray}} Fissiles) can be found in these bodies. Their abundance and distribution depend on dice rolls cast during world generation. Certain orbits also allow the harvesting of {{icon|antimatter|bgcolor=DarkSlateGray}} antimatter after the relevant technology has been researched.

Some celestial bodies will always be far more valuable than others in terms of resource availability and ease of extraction. Early resources on [[the Luna|Moon]], for instance, are far lower than [[Mars]] (which is typically the main expansion point in the early game). Space bodies in the outer solar system are also generally richer, to encourage further expansion, and as previously noted smaller space bodies may not allow the construction of higher tier bases – different bodies and orbits will carry different material or strategic value depending on the player's needs in a given campaign.

=== Resource Formulas ===
<i> This section discusses how the output values for each hab site are calculated. For a list of hab sites and mining profiles, as well as their stats, see [[Hab Site List]] and [[Mining Profile List]] instead. </i>

The game assigns every hab site a mining profile, which is essentially a set of values used by the randomizer to determine the resource outputs of the hab site. Specifically, for each of the five basic space resource types X, the mining profile contains:
* X_mean: The median output value for resource type X.
* X_min: The minimum output value for resource type X.
* X_jump: The chance to jump the output value away from the median for resource type X. (An unlimited number of jumps are possible.)
* X_width: The distance moved by each jump.

The mining profile also contains the special true or false value:
* modifyBySize: Whether the above values should be modified by the space body's mass and density.

The mass and density modifiers are calculated as follows:
<pre> Mass Modifier = Min(1, Space Body Mass (kg) / 50000000000000000 kg) </pre>
<pre> Density Modifier = Min(1, Space Body Density (g/cm³) / 1.25 g/cm³) × Max(1, Space Body Density (g/cm³) / 3 g/cm³) </pre>

If modifyBySize is true, then the Mean and Min values are modified as follows:
* For {{icon|water|bgcolor=DarkSlateGray}} Water and {{icon|volatiles|bgcolor=DarkSlateGray}} Volatiles:
<pre> Actual Value = Base Value × Clamp(Mass Modifier, 0.75, 1.25) </pre>
* For {{icon|metals|bgcolor=DarkSlateGray}} Metals, {{icon|nobles|bgcolor=DarkSlateGray}} Nobles, and {{icon|fissiles|bgcolor=DarkSlateGray}} Fissiles:
<pre> Actual Value = Base Value × Clamp(Mass Modifier × Density Modifier, 0.75, 1.25) </pre>

Regardless of whether modifyBySize is true, these numbers are also multiplied by the [[Game_Options#Mining_Productivity_Rate|Mining Productivity Rate]]. This is a slider you can adjust in [[Game_Options#Customize_Campaign|Custom Campaign Settings]]. When playing with a Full Solar System, it is 100% on Long Campaign mode and 200% on Accelerated Campaign mode. Smaller Solar System sizes increase this setting to compensate for the fact that they have significantly fewer hab sites.

The Width values are also modified by the [[Game_Options#Mining_Productivity_Rate|Mining Productivity Rate]] as follows:
* If [[Game_Options#Mining_Productivity_Rate|Mining Productivity Rate]] < 200%, then:
<pre> Actual Width = Base Width × Mining Productivity Rate </pre>
* Otherwise:
<pre> Actual Width = Base Width × (2 + Mining Productivity Rate ^ (1 - Jump) ) </pre>

Finally, if the Min values are greater than 0, then they are also randomized as follows:
<pre> Actual Min = Base Min × (0.8 to 1.2) </pre>

After all these modifiers are applied, the game now calculates the hab site's monthly output value V for each resource type X as follows:
# Repeatedly flip a weighted coin with X_jump chance of landing on heads, until it lands on tails.
# Set V to the number of heads.
# 50% chance: Multiply V by -1. 
# Multiply V by X_width.
# Add X_mean to V.
# Add a random value between -(X_width / 2) to (X_width / 2) to V.
# If V is less than X_min, then set V to X_min.
# If V is less than 0.01, then set V to 0.

In the case of {{icon|nobles|bgcolor=DarkSlateGray}} Nobles, there is one final modification:
# Let M be the {{icon|metals|bgcolor=DarkSlateGray}} Metals output value, and N be the  {{icon|nobles|bgcolor=DarkSlateGray}} Nobles output value.
# Divide M by either 2 or 3 (50% chance for each).
# If N > M, then set the {{icon|nobles|bgcolor=DarkSlateGray}} Nobles output value to M.

== Orbital Debris ==
<blockquote>
This orbit has ■■ dangerous cloud(s) of debris from space assets that have been destroyed here. Debris clouds present a hazard to undefended stations.
</blockquote>
~ Space UI Tooltip, Terra Invicta, 0.4.90.

Orbital Debris is currently a relatively unimplemented part of the game, with very few ways to affect it, and very few effects from it. So it is rarely worth paying attention to. Nevertheless, this section provides the details on the current mechanics for orbital debris.

{| class="wikitable sortable" style="text-align:center;"
|+ Methods for Creating Orbital Debris
|-
! Method !! Condition(s) !! Orbital Debris Created
|-
| Destroying a [[Spaceships|Ship]] || In Combat || 1
|-
| Destroying a [[Habs|Hab]] || Violently || Hab Tier
|-
| The [[Orbital Debris Strike]] Event || Depends on option picked || 0 to 1
|-
| The [[Anti-Satellite Test]] Event || Depends on option picked || 0 to 5
|-
| The [[Destructive Testing]] Event || Depends on option picked || 0 to 5
|-
| The [[Kessler Syndrome]] Event || None || 10 
|-
|}

{| class="wikitable sortable" style="text-align:center;"
|+ Methods for Removing Orbital Debris
|-
! Method !! Condition(s) !! Orbital Debris Removed
|-
| rowspan=2| Every January 1st || < 5 Orbital Debris, 25% chance || 1
|-
| ≥ 5 Orbital Debris || 0% to 15% of Orbital Debris
|-
| The [[Debris Duty]] Event || Depends on option picked || 0 to 1
|-
| The [[Low Earth Orbit Cleanup]] Event || Depends on option picked || 0 to 6
|-
|}

The only effect of orbital debris is to enable some events or weight the target selection of some events when they trigger:

{| class="wikitable sortable" style="text-align:left;"
|+ Events affected by Orbital Debris
|-
! Event !! Condition(s) !! Notable Event Effects
|-
! [[Kessler Syndrome]] 
| 
* Enabled by ≥ 40 Total Orbital Debris in ISS, Tiangong, LEO1, and LEO2.
* Can only happen once per game. 
| 
* [[Nations#Changing_Public_Opinion|Global Propaganda]] for {{icon|appease}}[[The Protectorate]] of strength 9 to 11.
* -10% {{icon|mc}}Mission Control Capacity for all Human Factions for 3 months.
* -8% to the [[Nations#Per_Capita_GDP|$3 Base GDPPC increase]] from {{icon|economy}}Economy Priority for 12 months.
|-
! [[Orbital Debris Strike]] 
|
* Enabled by > 0 Orbital Debris in Orbit.
* More likely to target Habs in orbits with more Orbital Debris. 
| Destroy up to 6 modules.
|-
! [[Debris Duty]] 
| 
* Enabled by > 0 Orbital Debris in Orbit.
* More likely to target Habs in orbits with more Orbital Debris. 
| Give 50 instant {{icon|research}} or Remove 1 Orbital Debris.
|-
! [[Low Earth Orbit Cleanup]] 
| Enabled by ≥ 10 Total Orbital Debris in ISS, Tiangong, LEO1, and LEO2. || Options to pay resources for [[Nations#Changing_Public_Opinion|Global Propaganda]] and Remove up to 6 Total Orbital Debris in ISS, Tiangong, LEO1, and LEO2.
|-
! [[Orbital Debris Near Miss]] 
|
* More likely to target Habs in orbits with more Orbital Debris.
* Can only happen once per game. 
| Give 50 instant {{icon|research}}.
|-
|}


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[[Category: Major Articles]]