Before we discuss designing and using mines in the game, lets see what they usually are used for.

Mines got two main uses - defense of local area or prevention of enemy to use an area safely.

The first option usually uses controllable mines. The mines may even be linked to automatically coordinate their attacks towards the enemy. Usually defensive mines are known as they also may pose as navigational hazards in peace time. These mines may be put into action pretty fast as they are pre-deployed and may even be remotely controlled so they can attack enemies far outside their own sensor range.

As an offensive weapon it can be used to prevent the enemy to make safe use of refuel points and planets. These types of mines are usually inserted covertly one way or the other. Either by dedicated vessels or just dumped out the cargo hold as a trader in disguise orbits an enemy world. The latter method are quite inefficient for deployment and may be quite risky. If the target planet got good sensor coverage en frequent patrols, they may suspect foul play when a lot of new contacts appear near the ship.

Deployment

There is several ways to deploy mines. They come down to three methods. Either by dedicated mine laying vessel. The most efficient way is to deploy mines with dedicated vessels. These are buildt with large internal magazines holding thousands of mines. Mines are launched out with launch tubes much like the ones used for fighters from carriers. However, with a couple if major differences. The deployment rate are far greater than normal launch tubes and each mine may be given its own vector which ensures a proper spread.

Another major advantage is that the mines deployed this way can be deployed far out from their target orbits.With the proper vector there are limited need for breaking thrusters.

The least favourable way is to just dump them out the cargo hold and hope they settle in some sort of arbit that can pose a threat. There is little control over the distribution and it takes time to deploy a large number of mines.

A third way to deply mines is to mount them on bosters that transports them into position. This can be fine, but require volume dedicated for boosters and typically a missile turret or barbette. In additon the signature from the booster may alert the locals that something fisky is happening. So this type of deployment are not very efficient when it comes to large numbers of mines, but may be used to get mines into spesific positions.

Mine Design

Mines are in essence engineless missiles with an important difference. They are expected to stay operational for years if need be.

Mines comes in three main categories; Dumb, Smart and Controller

Dumb mines are just that a mine with nothing more than a warhead and a few hours of battery life for the sensor when activated. This type of missile must be controlled either by a controller or from other type of control center. It has no capability to engage or track targets without outside help. This type of mine are often found in defensive mine fields. As teh mine has a minimum requirement suite of sensors the mines may be set to attack anything that it detects. However, the capability of the mine itself won't be able to distinguish between friend foe or voalidity of the target. In a wors case scenario, the mine may even attack other mines in the field. This kind of setting are usually set as last resource. Dumb mines with this setting got the same attack rating as the FIMs of equal TL minus 2. A mine field with only dumbmines like this will have their average density multiplied with 0.6 before other modifiers are counted in. See below. Dumb mines set to kill whatever it detects will keep running until the batteries run out. After that they will go inactive.

Mines may be designed with nuclear pumped laser with extended range. Even if the mine doesn't have the cabability to engage targets that far away due to limited sesnor range. However, in those cases mine controllers either on ground or automated may do the targetting for the mine.

Smart mines are unlike dumb mines able to engage targets after a preloaded target list or just based on IFF signatures alone. Smart mines usually have solar cells for power source to give it the power needed to operate both the sensor and the robotic brain. Some mines may have a combination. Using batteries until they run down, deactivate and use solar panels to collect enough power to fill up the batteries. However, this is a very inefficient way top operate so this type of mines are clearly in the minority.

Smart mines can also be controlled by a controller ensuring proper sensor coverage and capability. Smart mines usually require more power and in most cases must use solar cells with extendable solar panels to ensure high enough power output. This of course increases the sensor signature against active sensors.

Dontrollers are the ultimate mines. usually they do not have a warhead. But instead they are loaded up with advanced sensor systems which have better ranges that smart mines. As it takes several thousands of mines to get a proper coverage of a target world Controller Mines usually flies at 10 diameters or higher scanning for targets. When one is found, one or more mines are assigned to the target.

Usually several controllers are deployed if the mine field is large or a lot of traffic is expected. It also ensures that the field can operate if a controller malfunctions or are destroyed.

Most mines and all controllers got self destruct functions to prevent capture and tamping.

Clearing mine fields

Clearing mine fields are a dangerous job. Usually clearing mines are done with specialized small crafts with small drones armed with mass drivers and kinetic rounds. The mine clearing craft usually uses powerful sensors and try to stay clear of the minefield while the drones go in and disables any found mines.

Kinetic rounds has lower chance of accidentally detonate the mine than a high powered laser beam. A nuclear detonation will alarm any controllers and ensure a counter attack. Exploding nuclear warheads will also make it harder to keep track of already detected mines and the detection of new mines due to the EMP burst. Likewize will most minefield be controlled by mine controllers to prevent mines to knock each other out and affect sensor readings. Thus mines will be coordinated to attack in such a way that EMP bursts and other interference will have as little impact as possible.

Even if the mine clearing craft stays out of the field an mine controller will notice if mines under its controll goes offline without prior warning. The controller may then start searching for obvious culprits and alter orbits of mines to counter attack.

Design Constraints

There are several constraints when it comes to designing mines. Power supply and sensor ranges are the most important. Batteries can ensure usually only a couple of months worth of power. Combined with solar cells the active time decreases sharply as it needs to go offline to recharge batteries.

Mines rarely has active sensors or else they end up as targets pretty fast. Sensors are also the most power hungry item in a mine. That and limited sensor array size unless the mine is going for a deployable array. This will increase the sensor signature. Thus most mines have only 300 or 3000km short range. In a way this is good as a uncontrolled minefield could cause too many mines attacking the same target. drawback is that there will be gaping holes in the mine field.

Controllers usually have 30K Km short range, thus having a larger sensor signature.

Knocking out mines with nukes are possible, but will be very expensive as the blast wave has very little effect after a few thousand meters as there is no atmosphere to transfer the shockwave. As mines are armored, the metalic hull will work as a farrady cage. However, a nuclear burst in a minefield can temporarily blanket out the area making detection virtual impossible for the next hour or so.

Another way to disable mines are to use nuclear dampers and provoke them to explode, which fires the triggering mechanism, but doesn't ignite the fission/fusion process, thus turning the mine effectively into a dud. However, when the nuclear damper beam is removed, the mine is back to being dangerous unless the detonation charge hasn't been triggered.  

Game rules

Mines can be designed with the FF&S rules as usual. No special consideration are needed. Smaty mines can be designed with either the same controll package from this article. To give the mine more  capability and autonomy it may be given a robotic brain. If a brain is installed it should have the sensor skill and suiteable weapon skill. All mine controllers that are supposed to be autonomous must have robotic brain. The controller  must also have sensor and appropriate weapon skill. In addition it can several other skills to improve its capability.

A smart mine with a FIM-like control package may be programmed in the same way as missiles. But the control package will never be able to spot deception or tamper attempt. However a Robotic brain may attempt to spot a deception and roll a difficult task towards intelligence.

As mentioned above mines can be either deployed by jettisoning them out the cargo bay or by using a mine launcher. Mine launchers are designed as launch tubes, but uses 26 times the volume of the largest mine it is going to deploy. The power use are also 4 times higher than normal launch tubes to enable it to deploy up to 4 mines a minutes. Which translates to 120 mines a space combat turn.

Mines storage in a magazine to feed the launch tube takes the volume of the mines times 2 and mass 0.5 tons per Kl. Price is 0.015 pr Kl. There is no power requirements.

Mines can be placed anywhere on the map, but usually around planets or important locations as asteroids which holds bases.

Field density are the paramount for a minefield to be successfull. It doesns't need to be water thight, but be dense enough to attack often enough to make the enemy worried and assign resources for field cleaning.

As a rule of thumb 100 mines in a hex gives a density of 5% for 300Km sensor range mines and 15% for 3000km sensor range mines. Add the controllers Intelligence if one or more controllers are present. Additional controllers add 2% per controller. For every 10 mines above 100 adds 1% for 300km sensor range and 3% for 3000km range.

A quick and dirty way to generate density is to roll 1D6 times Short sensor range of mine and take the cube root of the result. Add two to the roll if controllers are present.

Resolving mine attacks are much the same way as for land mines. When a craft flies through one or more hexes with mines add up the squares and multiply with average hex density number. For instance a craft flies through three squares of a minefield with a density of 18%. Multiply 3 with18% gives a result of 54. A roll of 54 or less on a D100 results in an attack.

However, the value above is the base chance of attack. Take appropriate passive sensor signature of the target craft and multiply with 10. Small target will add 10 to the attack chance increasing it to 64% unless an EMM are installed. Then the chance is reduced to 54% as EMM reduces signature with 1 towards PEMS sensors.

Dropping decoys reduces the chance of attack with 0.5% pr decoy.

Each nuclear damper used reduces the attack probability with 1D6%

If the starship captain suspects he is entering a mine field he can try to evade the mines. To do so he needs to go in with active sensors. Roll a difficult sensor task. If it succeeds, reduce the attack chance with 1% per sensor and astrogation skill of the pilot and sensor operator. If the task fails nothing changes. But on a catastrophic failure increase the chance with 2D6%.  The attach chance can't drop below 5% or exceed 95%.

Resolve the attack as normal missile attack using the skill rating of the attacking mine. However, unless the attack destroys the target it is a possibility that other mines also attacks as the crafts travels through the hexes. If the chance roll was less than half the required another attack is possible. From the example above, the chance roll needs to be 27 or lower. So long as the chance roll continues to be lower than half of the required target number new attacks are possible. The number of attacks are also limited to 2 attacks pr hex if the mine sensor ranges are 300 or 3 attacks per hex for longer sensor ranges. One additional attack is possible if a controller are present. In the above example with 300km sensor range on mines and controllers would give up to 7 possible attacks.

Contributors

This document wasa inspired by the commerce raiding thread on CotI. A few people on the TNE mailing list has more or less directly contributed to this article. Their names are:

• Roger Clark
• Tim O'Reilly
• Richard Perks
• Eamon Watters

Thanks for your help.