Space Combat

Space is unbelievably vast, with celestial bodies separated by millions of kilometers. Encountering another spacecraft by accident is a literally astronomically small proposition. However, the emptiness of space also makes detecting another vessel through sensors extremely easy if those sensors know what to look for. Civilian ships (and military ships when not at war) are legally required to broadcast their names, registry numbers, and positions from transponders that can be detected by all standard ship sensor packages, which also aids in preventing collisions near space stations or along common routes.

Actual combat between peer space navies has never occurred in the history of humanity. Most space combat is conducted between armed civilian vessels, usually piracy, or between criminal ships and military ships pursuing them. Despite this, much literature has been written on how peer combat would be conducted and the defense force of every colony is theoretically prepared for such an occasion should it arise.

 Detection 

Ships are equipped with varied sensor packages, including radar, ladar, thermal scanners, and infrared and ultraviolet sensors. These consist of passive sensors (which are constantly on and feeding data to the ship's computers) and active sensors (which must be consciously turned on and used to sweep either the entire surroundings or a particular area). Should a ship illegally disable its transponder and shut off its engines to avoid thermal detection at long range, it can hide relatively effectively from passive sensors. Hiding from active sensors is very difficult and generally requires utilizing other objects to disguise its signature or block scanners. Some military experimentation has yielded success in stealth ships that use radar and laser-absorbing shapes and materials and onboard heat sinks to hide from thermal, radar, and ladar detection.

 Weaponry 

Civilian ships may legally only carry semi-automatic cannons up to 120mm caliber. These are intended for destroying rogue space debris that could be on a collision course without requiring the ship to spend fuel and acceleration changing course. Simple unguided projectiles like cannon shells and dumbfire rockets require computer calculation of the speed and trajectory of both the ship and the target to allow for the projectile to intercept its target; against an enemy vessel in combat, unguided projectiles must be fired very fast (such as from railguns) or at very short range to prevent basic evasive maneuvers from allowing them to dodge. Point defense cannons (PDCs) are often based on the Gatling or Metal Storm principle to fire a massive number of projectiles at a very high rate of fire, making it easier to walk fire onto a target.

Preferred projectiles are guided missiles, which can utilize onboard sensors and maneuvering jets to track a target and change course. Simple and inexpensive missiles rely on constant input from the ship's sensors (such as a laser lock) to identify and follow a target, while more advanced missiles have sufficient sensors that they can acquire their own lock even if the host ship ends its acquisition. These include visual scopes that can memorize the shape of a target vessel, allowing it to recognize and ignore a decoy. Because of the difficulty of making a direct hit, missiles often have very powerful warheads to allow for a damaging proximity detonation.

The most powerful non-nuclear weapons used aboard spacecraft are railguns, which use electromagnets to accelerate a dense tungsten projectile to extremely high velocity. These range from small turrets to fixed spine-mounted railguns on large military vessels. These spinal railguns require the entire ship to turn for aiming and can still be dodged by faster ships at long range, making them close-range battle finishers.

Laser weapons have the advantage of light speed velocity, making them impossible to dodge. They tend to have lower power than projectile weapons of equivalent size and the ponium-fluoride used in plasma sheaths easily absorbs their heat, making them ineffective against shields.

 Defenses 

Spacecraft are sealed against the vacuum, making any damage to the hull extremely dangerous. Therefore, most defensive strategies are based around not getting hit in the first place. Smaller ships are more agile due to requiring less thrust to move faster, which allows them to easily dodge unguided projectiles except at very close range. More massive ships may be unable to move in time, requiring them to utilize PDCs to shoot down incoming projectiles or jamming to scramble active locks from guided missiles.

All modern ships are equipped with a plasma sheath, which uses an electromagnetic field to hold a shield of charged ponium-fluoride, or PF particles, 10 meters away from the vessel. Most vessels only have simple shields designed to vaporize small space debris before impact, which are insufficient to protect against serious weaponry. Larger shield generators designed for defense can vaporize projectiles and detonate missiles away from the hull, but are costly and heavy. Manipulation of the electromagnetic field can open quick holes in the shield for firing weapons through it without dropping the entire field.

Plasma sheath shields function as a store of DR kept aboard the ship in the form of ponium-fluoride. This store can be distributed by manipulating the electromagnetic field, providing variable strength to different sectors around the ship. It's the responsibility of the ship's shield technician to distribute this strength to appropriate areas, strengthening shields on sides that are about to see weapons impact. This DR is ablative and permanently destroyed when it absorbs damage, reducing the amount of protection available for distribution. Ordinarily the electromagnetic field is shrunk to allow the PF to be guided back into the vessel for reuse; disabling the shield generator can cause the field to suddenly collapse, scattering the PF into space and causing it to be permanently lost. PF must be regularly restocked during refitting like any other consumable.

 Space Combat Doctrine 

The doctrine utilized varies depending on the capabilities of both ships in combat. The most common combat occurs between armed civilian vessels such as freighters and transports, either a personal conflict or piracy. This combat typically involves unguided weaponry such as semi-automatic cannons that are legally available and relatively inexpensive, as well as black market weapons such as dumbfire rocket pods or primitive guided missiles.

When combat is expected, it's considered preferable to place all members of the crew in spacesuits and vent the air from the ship. This prevents decompression in the event of a hull breach at the cost of making the crew reliant on their suits for survival even if no breach is made.

When utilizing cannons firing unguided projectiles, the ship must get as close as possible and orient itself to give its cannons an angle of attack. Cannons are often fired manually with computer guidance to create a firing solution, allowing the user to simply point and shoot. At sufficiently close range to make evasive maneuvers impossible, the attacking ship fires. Defense against this tactic relies on detecting the incoming vessel and either firing at it first or having sufficient armor and shields to absorb hits. Guided missiles are often fired at close range as well, as the inexpensive black market missiles typically used in these fights require constant sensor lock from the firing vessel and jamming is relatively easy.

In the untested doctrine of peer naval combat, large swarms of self-guided missiles (and cannon fire at close range) are used to overwhelm a target's defenses. The ship under fire attempts to maneuver out of the way of incoming projectiles and uses PDCs to shoot them down, including lasers turrets, while firing its own swarms. Railguns are used at close range, with the spinal rail guns of large naval vessels easily being capable of ending a fight on their own.

Boarding is possible against a disabled or surrendering ship. Should the engines be disabled, the boarding ship can easily perform a burn for an intercept course and dock with it. If the ship is still capable of fleeing, magnetic grapples can attach to the hull to reel it in. If the ship has not surrendered peacefully, the airlock is blown open and the ship boarded for close range combat.

As combat occurs, all members of the crew coordinate from their stations to maintain maximum combat capability. The pilot places the ship on courses that provide the best angles for weapons and shields while also performing evasive maneuvers, engineers redirect shields to provide optimal protection relative to threats and repair damage to the vessel when possible, sensors officers maintain communications and jam enemy ships, and gunners man weapons. The captain, if separate from any of these positions, monitors the tactical situation and gives orders.