Meteor Defence

Meteor Shower Frequency
A meteor shower spawns after a timer with a random duration expires. The timer is reset each time there is a meteor shower. The timer duration is a random number between 1 and whatever the meteor frequency mod setting is (defaults to 20).

The random time between showers means you can't always be sure that your defences will be recharged before the next one. Although it can be good to have backup defences you need to factor that risk against the constant power draw.

Currently all (occupied) surfaces have meteor showers simultaneously, but this is planned to change.

Meteor Count
The number of meteors is geometrically distributed with parameter 50%, so you have a 50% chance for 1 meteor, 25% for 2 and so on.

The probabilities for each number of meteors are:
 * 1) 50%
 * 2) 25%
 * 3) 12.5%
 * 4) 6.25%
 * 5) 3.125%
 * 6) 1.5625%
 * 7) 0.78125%
 * 8) 0.390625%
 * 9) 0.1953125%
 * 10) 0.09765625%
 * The probability of getting 11 or more meteors is 0.09765625% = (1 - 0.5)10

Meteor Defences
All meteor defences need ammunition and power. Then need to charge up before they can fire. While charging the energy requirement is increased. When fully charged there is a passive power draw to keep it ready.

The Meteor Point Defence has a range of radius 64 tiles. This is good and bad. The bad is that it won't protect everything. The good is that it won't waste shots on things that don't matter. It is good for protecting high value locations like reactors, warehouses, and rocket silos. They can also have 4 shots loaded and charged, each with 50% accuracy.

Meteor Defence Installations have unlimited range and 80% accuracy. They will try to protect the entire surface OR orbit (whichever it is built on). This means they will waste shots on protecting areas that don't matter.

Defences fire in sequence to see if they hit. If there are still meteors left then the next defence fires until there are no meteors left, or no defences that can fire. Ammo and energy is not wasted firing at meteors that have already been destroyed.