Data File Updated: Wednesday, May 15, 2019
The only forces that can attack an enemy star system are various kinds of starships. The most important defense element for any star system is also a starship, because it is mobile and can be where it needs to be at the appropriate time to face, follow, pre-empt or avoid an enemy force. Purely defensive units and installations have limitations, chiefly that they are usually confined to a single system or location within a system, and therefore can sometimes be avoided by a disobliging enemy. However, there are often instances where a less-expensive specialized system defense unit makes more sense than a more-expensive multirole starship, and there are some instances (such as the protection of a large orbital spaceport) in which making such large craft jump-capable is impractical.
The descriptions of system installations below are most specific to Loroi examples, but apply in general to any starfaring civilization at a similar level of technology.
The number, size and capabilities of system installations in a particular star system will vary depending on the location of the system (especially in relation to enemy borders), whether it has inhabited worlds or outposts, and whether there is significant transit traffic to and from nearby systems. A remote, uninhabited system might only have a single system buoy, whereas a homeworld may have dozens of stations with a wide array of facilities.
With only a few exceptions such as ground bases, system installations such as space stations are NOT "fixed." Although they usually have no FTL drives, all of the installations listed here are spacecraft, with at least some limited ability to maneuver. Propulsion is necessary even for the most basic satellites to maintain a stable orbit, and is especially necessary for station-keeping in areas (such as near a jump zone) which are not orbital. Maneuverability is also necessary to avoid kinetic kill weapons which, while very primitive, are also catastrophically damaging if they can score a hit.
The most basic installation that will be in any controlled system is at least one System Buoy, usually a small unmanned satellite. The System Buoy transmits a constant stream of ID and traffic control information, notifying passing vessels of system conditions and hazards, and keeping a record of system transits. The buoy is usually interactive and can be used by passing ships as a signpost to leave messages and upload and download news and network updates. Lone buoys are often placed in a long comet-like orbit well out of the planetary plane of the system, to keep interaction with system bodies to a minimum. Systems with a lot of activity will have many such buoys at various locations throughout the system, and a plethora of additional special-purpose buoys for a variety of uses.
In the absence of faster-than-light communication technologies, messages must be carried by starships. However, a ship carrying conventional mail can require weeks or months to travel from one location to another. The answer to improving the speed of communication (vital to the operation of an interstellar empire) is to use a kind of pony-express relay system, that is an empire-wide network of courier vessels and relay stations known as a Command and Control Network. The CCN works by using courier starships to make jumps between star systems, but then using in-system communication infrastructure to transmit messages across the system to another courier starship waiting at the next jump point. This means that the message can cross the system at the speed of light, instead of being restricted to the realspace speed of a courier ship that has to cross the system. A typical distance between jump points at opposite ends of the same system is 80 Light Minutes, and a courier vessel can get underway and up to jump speed in about an hour, so it is possible for a message to cross ten systems in less than one day.
So, if a system is a part of the CCN, it will have at least two Relay Bases situated near to the applicable jump zones that lead to adjacent systems in the network. Each of these bases will have at least basic communications infrastructure for broadcasting clear messages across the system, but more importantly will have fuel and operations facilities for a stable of courier vessels. These couriers will operate between the Relay Bases on each side of the jump link between the two stars like net runners in a tennis match; a courier after delivering a message will usually stay on the far side and refuel, while another courier from the opposite base will make the return jump.
For systems near a source of threat (such as an enemy border), even if it isn't a normal part of the CCN, observation posts to watch for incursions must also have similar bases that support couriers so that any information gathered can be relayed to headquarters.
Jump Link Traffic Control Issues
Because the only way to get information from the neighboring system is via the arrival of a starship, there is a limited amount that can be done to predict when and where an inbound starship will appear. Normally, the chance of collision between inbound and outbound starships is very unlikely, due to the scales of the space involved. However, if there is enough traffic through a particular jump link, the chances of collision may rise to the point where it may be necessary (even if only for reasons of psychological reassurance) to implement some kind of jump traffic control scheme. Possible strategies include:
Whether in various planetary, moon, or solar Lagrange orbits, or keeping station near a jump point, space stations are functional spacecraft with at least some ability to maneuver. Battle Stations designed for combat may have thrust capability as high as 5g and can change system locations on their own; stations with less robust acceleration capability may rely on tugs to move them in a more timely manner.
Various types of space stations can serve one or multiple functions:
Space Platforms vs. Battle Stations
Base Stations or "Battle Stations" are spacecraft with rigid hulls that are like starships in most respects, but are optimized for system defense and have no jump drive and much more limited propulsion. "Space Platforms" tend not to have rigid hulls and are often modular, more fragile than bases, but not as limited in size or growth potential. Platforms are generally not designed for combat and therefore may suffer catastrophic structural failures if they receive damage from weapons fire. Our contemporary space stations such as the ISS or Mir would be considered space platforms.
The Loroi term for a large, hardened, weaponized battle station is a "Citadel." Loroi Citadels at frontline locations such as Seren or Azimol have seen direct action and over the years have grown to formidable sizes. Though Citadels are usually designed around combat capability, they often provide a multitude of station facilities: headquarters, logistics, support, habitat, fighter hangars and extensive heavy weaponry and protection.
The largest battle station in Loroi space is Seren Citadel, located in the sector capital near the Charred Steppes. The first incarnation of the citadel saw heavy action during the first Siege of Seren early in the war, and was destroyed when Seren fell to the Umiak in 2139. It was rebuilt when the Loroi recaptured Seren in 2145, bigger and better than before.
A battle station would be cheaper than a comparably-sized starship, but not by orders of magnitude. A battle station needs pretty much all the same systems that a starship has, except for jump generators. A battle station still needs engines, though it can spend less on the drive components, and you'll still want artificial gravity and inertial dampers. It can be larger and heavier than is practical to build most starships, as it doesn't need to be as mobile and you don't have to worry about jump field coverage, though if it's very large it will probably have to be constructed in-system. It will also be able to divert power that would have gone for high acceleration into heavier weaponry.
I would guess that a battle station would cost perhaps 75% as much as a starship of the same size, but is probably better armed. If you have border systems like Seren or Azimol with important bases that come under regular attack, then I think it will make sense to build up a certain amount of local defenses. There are very few border systems that still have large civilian populations, so what needs to be protected is primarily your military bases and their supporting infrastructure. If the system needs orbital infrastructure such as spaceports and depots and shipyards, then it makes some sense to build them as hardened, armed stations that are more likely to survive an attack (rather than constantly rebuilding cheaper civilian platforms that are frequently damaged or destroyed). Second, while it's true that battle stations can't leave the system to aid in an attack on a different system, even the Loroi won't want to move 100% of their forces to every hotspot; Farseers are not 100% reliable, and important bases like Azimol and Seren will need some kind of defense all the time, regardless of whether there are attacks elsewhere. Battle stations can move anywhere within a system, just not as quickly as more conventional warships, and smaller battle stations can potentially be relocated to other systems by jump-capable tugs.
Because the Umiak regularly and deliberately attack high-value Loroi targets rather than trying to bypass them (in order to force the Loroi to defend and thereby expose themselves to casualties), I think it makes sense for the Loroi to build fairly large and well-armed citadels in the major frontier bases, supported by numerous smaller battle stations that can be redeployed throughout the system as needed. If the planet has airless moons, these will be good sites for ground bases. If the planet is moonless, you might consider towing in an asteroid or two, but I'm not sure that's really necessary.
The Umiak don't have Farseers and so must keep defensive forces (or at least patrols) in every border system, so battle stations might make sense, but they maintain very large defensive reserve fleets that don't rush around to hotspots the way the Loroi forces do, so battle stations are probably not as necessary. It's also true that when the Loroi do go on the offensive, they have a better record of breaking through than the Umiak, so "fixed" Umiak defenses have a greater chance of being bypassed than Loroi versions. I would expect the Umiak to build mostly cheap orbital platforms for the infrastructure they need, and rely primarily on their extensive fleets for defense.
Starship fleets are usually a star system's best defense, and key systems that are near enough to enemy threats will often have starships based in the system or on regular patrol routes through the system. Systems with a significant civilian population will often have dedicated system security forces, sometimes under the control of the interstellar government, sometimes under the control of local governments or even private firms. System security forces will often be primarily concerned with local law enforcement.
If military fleets are not based directly in the system, it may still be possible to call for aid using the CCN (or more general courier vessels, if the system is not on the network).
A "monitor" is a military spacecraft that is identical in all ways to a starship with the exception that it does not have a jump drive. These kinds of warships most often find use in very heavily populated systems, where there will always be a need for protection that does not need to leave the system. Monitors will typically be used by local police forces or private security firms, whose interstellar jurisdiction may be sharply limited anyway.
Defense Satellites are dedicated weapons platforms, usually deployed as a last-ditch defenses around inhabited planets. DefSats are usually unmanned and often armed with point-defense weaponry, to protect a planet from missile barrages; however, some DefSats are larger and armed with anti-ship weapons.
Manned, maneuverable small craft are more expensive than DefSats but also more flexible. Fighters will usually be based on carriers or stations in the system, though they may also sometimes fly from ground bases on small, airless moons. Fighter bases are possible on inhabited planets, but the atmosphere and larger planetary mass will usually mean less than optimal operation for a space fighter.
Mines are not well suited to space combat, because space is big and ships are small; collision with a mine is astronomically unlikely. Even a remote-detonated mine with a relatively huge blast radius is still very unlikely to provide enough area coverage to be effective. Also, there's no way to conceal a mine in open space, so they are usually easy to spot and avoid (or destroy). Delayed-activation torpedoes can be used in special circumstances as a sort of mine, but this is a low-efficiency use of a fairly expensive resource.
Ground Bases are cheap and easy to maintain, but are often less effective than space-based stations due to the effects of a planet's gravity and atmosphere. Ground bases can be heavily bunkered and protected, but are vulnerable in the sense that they cannot dodge enemy fire, especially kinetic weaponry. Also, defensive screens do not operate well in atmosphere.
Ground-based defensive installations can include: fighter or missile bases, point-defense batteries, or anti-ship batteries. Infantry barracks or other ground-combat-oriented facilities are also common, but are outside the scope of this article.
An orbital elevator (which is a cable leading from the ground to geostationary orbit) is incredibly vulnerable and difficult to protect, and any station connected to such an elevator also becomes vulnerable because it loses most ability to maneuver. If threatened, a station may be forced to detach from the elevator cable so that it may maneuver freely, which may mean destruction of the elevator.
Small airless moons are ideal sites for ground-based defensive installations.
Defense Strategies and Defensive Tactics
Defensive installations alone can rarely repel a determined
fleet attack, therefore all viable defensive strategies are
centered around fleet battles, and the contribution of dedicated
system defense are usually secondary.
then becomes: where does the defender choose to make his stand?
The question then becomes: where does the defender choose to make his stand?
Defending Jump Zones
Any well-traveled system will usually want to have some kind of
station near the jump zone, to aid in traffic control, early
warning, and as a base for courier vessels if the system is on
the communications network. However, defensive installation will
often want to limit how close they are situated to the zone; in
addition to collision risks, they are likely to be quickly
destroyed if a major enemy force suddenly appears,
unless these defenses are very substantial.
Any well-traveled system will usually want to have some kind of station near the jump zone, to aid in traffic control, early warning, and as a base for courier vessels if the system is on the communications network. However, defensive installation will often want to limit how close they are situated to the zone; in addition to collision risks, they are likely to be quickly destroyed if a major enemy force suddenly appears,
unless these defenses are very substantial.
Denial of a Jump Zone
An oft-mentioned idea is to attempt to make an inbound jump zone unusable by flooding it with debris, in the hope that it will cause collisions with inbound enemy vessels. The first problem with this idea is that space is big and ships are small; it would require an incredible amount of debris to fill the ~1 AU wide volume that is a typical jump zone to any density that would make the chance of collision significant. The second problem is that this debris won't stay in the zone; because a jump vector is fixed in relation to a nearby star, debris placed in the zone will eventually fall in toward the sun or orbit out of the zone. The third problem is that such debris will pose a serious hazard to one's own side, both for friendly vessels that want to use that jump link, and for system safety in general as the debris diffuses out of the zone and clutters up the system.
Defending Planets and Key Infrastructure
In some situations, such as combat out in the no-man's-land of the Charred Steppes, there won't be any system installations to defend at all, and the combatants may maneuver through the system without restriction. In such a situation in which neither side has any assets that must be protected (other than the fleets themselves), one side may often be able to avoid combat if it chooses. In a controlled system with assets that need to be defended, the defender will be obliged to deploy his fleets to protect them.
If the defender chooses to deploy near the asset, he will have the advantage of whatever defensive infrastructure that has been built around that asset. He will also have more time to observe the enemy forces as they assemble at the jump point, and assess the enemy's strength and disposition. This will give the defender better options to retreat with his fleet intact if the situation seems untenable. The disadvantage is that the enemy will have time to marshal his forces in an orderly fashion. If there are multiple such assets, this may require the defender to split his forces.
If the defender chooses to deploy near to the jump zone, he will have the advantage of being able to oppose the enemy fleet entry into the system immediately, as the enemy vessels appear. The advantage is that the enemy is likely to be disorganized as they enter the system, and some species (notably the Umiak) will be at reduced efficiency due to the effects of jump sickness. The disadvantage is that the defender is committed to battle, and may have limited time to prepare and limited option to retreat if the enemy force is larger than expected. The defender must also be certain which jump link the enemy is likely to use; if the enemy enters the system from a different direction than expected, it may not be possible for the defending forces to redeploy in time to protect the key assets.
The defender can split his forces and guard multiple points, but this will often mean that those forces guarding the jump zone will be outnumbered and destroyed if the enemy comes through in force. (You can probably guess which side favors this tactic.)
In the state of the war at the time of the story, there are not many planets with major population centers near the front lines, as most of these have already been evacuated or depopulated, so most assets that must be protected are military and economic assets (bases, supply depots, resource gathering operations).
Ground combat is conducted with the same classes of weaponry we're accustomed to (infantry, armor, artillery, air), and won't be explored much in the story. Planetary invasions tend to be very one-sided affairs: whichever side has space superiority is going to have an enormous advantage in any ground combat, being able to pound targets from orbit with relative impunity.