Planetary defense posts can be used to hide the planet from various sensors. In addition, they contribute fighters, launch bays and beams to the defense of the planet. Finally, no planet without defense posts can attack an orbiting ship, and any orbiting starbase will have only its fighters.
The maximum planetary defense posts that a planet can support is the lesser of:
The number of colonist clans on the planet
TRUNC(50 + SQRT((Colonist Clans) - 50))
Defense posts will screen the planet's industrial activity from long range sensor sweeps by enemy ships. The odds of detection are (100 - (Number of Defense Posts) * 6.67 )%. If the planet has 15 defense posts, it will be completely screened from normal sensor sweeps.
When there are 20 defense posts on a planet, the planet will be hidden from Bioscanners.
Details on combat mass can be found here.
As the number of defense posts on a planet increase, so does the number of fighters that the planet contributes to its defense. The number of fighters that the planet contributes can be calculated as follows:
ROUND( SQRT( MAX(0, (Planetary Defense Posts) - 0.75)))
If there is one defense post, the planet will contribute one fighter to the defense. Each fighter lost in combat by the planetary garrison will remove one defense post; planetary fighters are lost after starbase fighters.
As the number of defense posts on a planet increase, so does the number of fighter bays that the planet contributes to its defense. The number of fighter bays that the planet contributes can be calculated as follows:
TRUNC( SQRT(Planetary Defense Posts))
If there is one defense post, the planet will contribute one fighter bay to the defense.
As the number of defense posts on a planet increase, so does the number of beams that the planet contributes to its defense. The number of beams that the planet contributes can be calculated as follows:
MIN(10, ROUND( SQRT(((Planetary Defense Posts) + (Starbase Defense Posts) + (Starbase Mass Bonus)) / 3)))
The Starbase Mass Bonus is 0, except for starbases in the radiation shell of a star cluster, which receive a 200 KT mass bonus. If there is one defense post, the planet will contribute one beam to the defense. The planet may not be defended my more than 10 beams.
As the number of defense posts on a planet increase, so does the power of the beams that the planet contributes to its defense. The beam slot of the beams that the planet contributes can be calculated as follows:
MIN(10, TRUNC( SQRT(Planetary Defense Posts / 2)))
If there is one defense post, the planet will contribute slot-1 beams (Lasers) to the defense. If there is a starbase in orbit around the planet, and the starbase has researched a higher level of beam, then that beam type will be used.
Planetary defense posts improve the ability of colonists to resist ground assaults. The defending planet's combat rating is calculated as follows:
1 + (Planetary Defense Posts / 20)
The advantages Ground Defense (Lizard) and Ground Defense (Fury) provide defenders of those races with a different base combat rating; instead of 1, they start with 15 and 5, respectively.
To get the overall defense ratio of the planet, multiply the planet's combat rating by the racial ground defense advantage. This is the number of attacking clans that are needed to kill one defending clan. Please remember that the racial ground attack advantages of the Lizards and Fury make one clan attack as though it's many clans.
For more information, please refer to the Ground Attack page.
If a planet detects that it is a victim of any of the Super Spy Deluxe or Super Spy Command missions and it has more than 30 defense posts, it can burn up 10 of the defense posts to emit an ion pulse that will decloak all cloaked ships in orbit.
A planet normally has about a 20% chance of pulling this off, but if its Friendly Code is changed to mfX , where X represents any character, then it will always trigger the pulse as long as the required defenses are present. In any case, there is no way for the planet owner to cause this to happen or turn it off.
This table shows the defensive capabilities that are delivered by various numbers of defense posts, up to a Colonist population of 10,000,000 (366 defense posts).
| Planet Only | Planet and Starbase | |||
|---|---|---|---|---|
| Defense Posts | Fighters | Fighter Bays | Beam Type | Beam Count |
| 0 | 0 | 0 | None | 0 |
| 1 | 1 | 1 | Laser | 1 |
| 3 | 2 | 1 | Laser | 1 |
| 4 | 2 | 2 | Laser | 1 |
| 5 | 2 | 2 | X-Ray Laser | 1 |
| 7 | 3 | 2 | X-Ray Laser | 2 |
| 9 | 3 | 3 | X-Ray Laser | 2 |
| 13 | 4 | 3 | Plasma Bolt | 2 |
| 16 | 4 | 4 | Plasma Bolt | 2 |
| 19 | 4 | 4 | Plasma Bolt | 3 |
| 21 | 5 | 4 | Plasma Bolt | 3 |
| 25 | 5 | 5 | Blaster | 3 |
| 31 | 6 | 5 | Blaster | 3 |
| 36 | 6 | 6 | Blaster | 3 |
| 37 | 6 | 6 | Blaster | 4 |
| 41 | 6 | 6 | Positron Beam | 4 |
| 43 | 7 | 6 | Positron Beam | 4 |
| 49 | 7 | 7 | Positron Beam | 4 |
| 57 | 8 | 7 | Positron Beam | 4 |
| 61 | 8 | 7 | Disruptor | 5 |
| 64 | 8 | 8 | Disruptor | 5 |
| 73 | 9 | 8 | Disruptor | 5 |
| 81 | 9 | 9 | Disruptor | 5 |
| 85 | 9 | 9 | Heavy Blaster | 5 |
| 91 | 10 | 9 | Heavy Blaster | 6 |
| 100 | 10 | 10 | Heavy Blaster | 6 |
| 111 | 11 | 10 | Heavy Blaster | 6 |
| 113 | 11 | 10 | Phaser | 6 |
| 121 | 11 | 11 | Phaser | 6 |
| 127 | 11 | 11 | Phaser | 7 |
| 133 | 12 | 11 | Phaser | 7 |
| 144 | 12 | 12 | Phaser | 7 |
| 145 | 12 | 12 | Heavy Disruptor | 7 |
| 157 | 13 | 12 | Heavy Disruptor | 7 |
| 169 | 13 | 13 | Heavy Disruptor | 8 |
| 181 | 13 | 13 | Heavy Phaser | 8 |
| 183 | 14 | 13 | Heavy Phaser | 8 |
| 196 | 14 | 14 | Heavy Phaser | 8 |
| 211 | 15 | 14 | Heavy Phaser | 8 |
| 217 | 15 | 14 | Heavy Phaser | 9 |
| 225 | 15 | 15 | Heavy Phaser | 9 |
| 241 | 16 | 15 | Heavy Phaser | 9 |
| 256 | 16 | 16 | Heavy Phaser | 9 |
| 271 | 16 | 16 | Heavy Phaser | 10 |
| 273 | 17 | 16 | Heavy Phaser | 10 |
| 289 | 17 | 17 | Heavy Phaser | 10 |
| 307 | 18 | 17 | Heavy Phaser | 10 |
| 324 | 18 | 18 | Heavy Phaser | 10 |
| 343 | 19 | 18 | Heavy Phaser | 10 |
| 361 | 19 | 19 | Heavy Phaser | 10 |
| 381 | 20 | 19 | Heavy Phaser | 10 |
| 400 | 20 | 20 | Heavy Phaser | 10 |
| 421 | 21 | 20 | Heavy Phaser | 10 |