Solar System

A view of the solar system up to the orbit of Jupiter

Terra Invicta models the larger bodies in Earth's Solar System out to a distance of roughly 50 times the distance of the Earth from the Sun. This includes much of the Kuiper Belt, the group of icy bodies orbiting beyond Neptune.

The Solar System also includes Lagrange Points as locations Fleets may travel to. These are stable anchorages created by the equilibrium of gravity between two Celestial Bodies and marked on the map with geometric shapes.

Gameplay and Mechanics

The number of objects in the solar system is chosen at the start of a new game. Regardless of the option chosen, all planets, moons, dwarf planets and major asteroids will be present.

Orbits

All celestial bodies and Lagrange Points have one or more stable orbits around them, pre-defined by the game, and where factions can locate fleets and build a limited number of space stations. Fleets and stations don't require any propellant to maintain a constant trajectory in a stable orbit.

Orbits close to a space body's surface are called interface orbits, and can be identified by a celestial body icon next to them. These are orbits that fleets can travel to in order to land or bombard targets on the surface. Around Earth, some hab modules grant bonuses providing greater benefits to the surface only if they are in an interface orbit.

Due to the lower gravitational pull, higher-altitude orbits typically cost less delta-v (Δv) when launching from them to local moons or other planetary systems. This concept is also known as "escape velocity".

A few orbits also produce extremely small amounts of antimatter that may be harvested with hab modules after the appropriate technology has been researched.

The game factors in gravity for all space maneuvers, and technically decaying orbits and stable orbits not pre-defined by the game are possible to achieve. However, this will rarely occur unintentionally through normal gameplay.

Lagrange Points

The Earth-Luna Lagrange points in Terra Invicta

Normally, two celestial bodies exert an unbalanced gravitational force at any given point between them, requiring a stable orbit to maintain a constant distance without the application of delta-v. An exception to this are Lagrange points.

Lagrange points are a location in an orbital system where gravitational forces and centrifugal forces between two celestial bodies are in equilibrium, creating a relative but consistent coordinate between two bodies where zero (null) gravity is constantly experienced.

For any planet or their planetary moons(s), five Lagrange points are always possible (L1 to L5). For example, this means Earth, which has a moon but also orbits the Sun, has five Lagrange points for the Earth-Luna orbital system, and another five for the Earth-Sun.

Terra Invicta does not provide defined Lagrange points for dwarf planets and their satellites, for asteroids and asteroidal satellites, or for comets and centaurs.

L1, L2 and L3, always correspond to a line drawn through two celestial bodies in orbit, each providing a single stable "halo orbit". L4 and L5 will always correspond to a point following or preceding the orbital path of the less massive body, providing a stable leading and trailing "trojan orbit" respectively.

Objects at Lagrange points always require zero delta-v to remain in position, and also have an effective escape velocity of zero. This means that as a rule of thumb, they are very likely to be the most efficient locations from which to launch ships or probes to any given destination, especially when targeting locations within their respective orbital system.

If a Solar Mirror, Automated Solar Mirror or Solar Array is built on a space station in orbit of any L1, L4 or L5 location between a planet and one of its moons, it will provide a bonus to solar energy production for any bases using solar power modules on that planet or that moon. The L1 between a planet and the Sun will apply this bonus to all bases in that planetary system.

Hab Sites

With the exception of the Sun, the hellish world of Venus, and the gas giants Jupiter, Saturn, Uranus, and Neptune, all space bodies have at least one hab site where factions may build a base (a hab on the surface of a body) by constructing any applicable "core" module at that site. Planets and other larger bodies will have up to 25 hab sites able to build Tier 3 base modules, and this number will decrease roughly in proportion to a body's diameter. Smaller bodies are also more likely to only allow contruction of Tier 1 or Tier 2 modules.

Mining

When a mine module is constructed, a base will continuously output a quantity of one or more resources to the faction that controls the mine. The type of resources generally depends on the composition of the space body.

When first viewing the Solar System, factions will only have estimates of the mining potential of a particular hab site. To discover their exact potential, they will need to conduct a prospecting survey of the parent space body.

Prospecting

To build a base, a faction must first survey the space body to determine the precise location for the habitat. Prospecting a space body will also reveal the exact mining output values of available hab sites.

Prospecting can be conducted by a probe launched from Earth or from a shipyard at a hab, or by ships equipped with a Mobile Space Science Lab module. Prospecting data may also be stolen from other factions using turned councilors, or shared with an Intel Sharing Agreement.

Each planet, with the exception of Neptune and Uranus requires a separate Space Science technology to prospect it and its satellites. The asteroid belt also needs a specific technology to begin prospecting there. Moons are unlocked by their parent planets, except for Luna which requires a separate but cheaper technology.

For a fleet to perform prospecting, it must contain at least one ship with the Mobile Space Science Lab module, and execute the Survey operation. This action takes 28 days, divided by the number of ships having lab modules. Multiple lab modules on a single ship do not affect the time.

Ship Interactions in the Solar System

Orbital bodies provide an important role for space faring vessels when travelling. Depending on the delta-v of a vessel, travel might be carried out by "hopping" between bodies for resupply, thus making their position crucial. Alongside this, several maneuvers such as aero-braking and gravity assists allow a fleet to "pivot" on a journey when travelling in space and connecting with a target. This leaves the player with an array of options for travel and base planning when expanding or pursuing their factions' interests.

See also

• Celestial Bodies
• Habs

External Links

• Delta-v (Wikipedia)
• Escape velocity (Wikipedia)
• Lagrange point (Wikipedia)
• Gravity assist (Wikipedia)
• Aerobraking (Wikipedia)