Is a planetary defense regiment (ground-to-space defenses) defined anywhere?

[Anonymous]

See lots of info for strength of space jump-capable units down to the exact size of subsector fleets.

See very little on system defense or planetary defense specifics, apart from occasional refences to missiles on a high port and SDBs/ammo hidden in asteroids, rings or gas atmospheres.

Is there a standard regiment?

But counting ships is easy. What ground bases or orbital bases cover a planet?

Orbital forts? Ground based ships? Surface-to-orbit missile bays? Buried meson gun? Army base?

"A cruiser" of bases is probably a meson gun, 20-30 missile bays and a fighter/SDB squadron. Using the fact that 4 satellites are needed for global coverage we quadruple the above to get all-round coverage for our planet. Maintenance for ships is cheap, so not sure putting that in orbital satellites is economical (especially with blind spots). But ground bases would be even cheaper and might be hidden.

edit: How is atmospheric point defense done? I believe rules say space-strength beam and sand are attenuated/useless in an atmosphere.

edit: 4 satellites, but that's to cover the surface form space, not space. 3 sats or ground bases should in theory cover space with some gaps at low altitude due to the planet's curve. IDK how satellites orbit so let's not get too deep into this. And of course a meson gun can fire through the planet.

 

[Reynard]

Remember that the Imperium does not extend beyond the fence on the ground and within the 100D except for the assets of Imperial Highports IF there is a Highport. This often means a system relies on their tech level and resources to raise and army and Close Orbit and Airspace Control Command assets. A world would need to be very important and/or have the support of a Naval Base for better protection.

MegaTraveller's COACC supplement as well as Marc Miller's Traveller Imperial Squadrons and Pocket Empires give some indication what could be available to a planet. If you get a chance to review T5's Resource Unit calculation and World Importance profile you would understand why defense is... chaotic. Realistically, it won't be every system's homeworld bristling with TL 15 battle stations and ground based defenses. This is probably why many systems rely on mobile warships for protection especially colonial fleet assets. They can be moved where potential threats may be.

 

[Anonymous]

I don't have those books. Do they provide just Cr guidelines, or also guidelines on what the Cr are spent on?

Isn't it a feudal system inside 3I?

A planet maintains its own defenses, and "tithes" a portion of that to subsector. You'd build a jump-capable ship as obligation to the subsector lord, but you're highly incentivised to build non-jump units for local defense so they don't get "borrowed", and they're also cheaper.

 

[AnotherDilbert]

See lots of info for strength of space jump-capable units down to the exact size of subsector fleets.

Only primary warships really. We know very little about bases, transports, logistics, ships like mine-layers/-sweepers, and reconnaissance.

Is there a standard regiment?

Not that I know of.

Orbital forts? Ground based ships? Surface-to-orbit missile bays? Buried meson gun? Army base?

Orbital forts does not really work in any Traveller combat system, afaik.

Any spacecraft weapon can be deployed on the ground, canon mentions lasers, missiles, and buried mesons.

The Imperial Army is not well defined.

Maintenance for ships is cheap, so not sure putting that in orbital satellites is economical (especially with blind spots). But ground bases would be even cheaper and might be hidden.

Fixed installations in space can be destroyed from stand-off range. Orbital fortifications has to be somewhat mobile (ships).

Buried mesons presumably work well.

edit: How is atmospheric point defense done? I believe rules say space-strength beam and sand are attenuated/useless in an atmosphere.

Lasers have reduced range, but still plenty in atmosphere.
Mesons are unaffected.
PAs work in atmo (charged particles) or in vacuum (neutral particles), not both.
Missiles have enough acceleration and endurance to be unaffected.

edit: 4 satellites, but that's to cover the surface form space, not space. 3 sats or ground bases should in theory cover space with some gaps at low altitude due to the planet's curve. IDK how satellites orbit so let's not get too deep into this. And of course a meson gun can fire through the planet.

Missiles can presumably fire over the horizon, we only need sensors in all directions.

 

[AnotherDilbert]

Remember that the Imperium does not extend beyond the fence on the ground ...

Not quite: Local jurisdiction ends at the starport fence (and 100D), but the Imperium extends throughout the system.

 

[Sigtrygg]

What about systems where the mainworld has colonised their entire system before joining the Imperium? What about the worlds of the original Sylean Federation which became the Imperium?
What about virgin worlds colonised by the Imperial Ministry of Colonisation?

The trope that the 'Imperium rules the space between the planets' is only part of the story.

It should read 'in frontier sectors the Imperium rules the space between the planets, while the planetary government is permitted extensive home rule'. Move towards the core sectors and the Imperium will/does directly rule a lot more real estate. remember this stuff is the Library Data written by the Imperium for an audience in the Spinward Marches...
The Imperium has never been described as an entirely space based culture composed of orbitals and O'Neill cylinders.

Back to the defensive strength etc - there was a JTAS article about planetary defense factor, which formed the basis for the rules in T4's Imperial Squadrons and Pocket Empires books.

It has long been an area that has cried out for more details.

 

[phavoc]

What about systems where the mainworld has colonised their entire system before joining the Imperium? What about the worlds of the original Sylean Federation which became the Imperium?
What about virgin worlds colonised by the Imperial Ministry of Colonisation?

The trope that the 'Imperium rules the space between the planets' is only part of the story.

It should read 'in frontier sectors the Imperium rules the space between the planets, while the planetary government is permitted extensive home rule'. Move towards the core sectors and the Imperium will/does directly rule a lot more real estate. remember this stuff is the Library Data written by the Imperium for an audience in the Spinward Marches...
The Imperium has never been described as an entirely space based culture composed of orbitals and O'Neill cylinders.

Back to the defensive strength etc - there was a JTAS article about planetary defense factor, which formed the basis for the rules in T4's Imperial Squadrons and Pocket Empires books.

It has long been an area that has cried out for more details.

As far as I can tell, there are numerous grey areas within the materials that explain how these things are worked out. Also would a space station count as ownership of the planet it is orbiting? Is there a specific population size that must be reached in order for the Imperium to allow a claim for a planet as more than just an outpost/colony?

 

[Condottiere]

If you have an effective enough navy, you don't need coastal forts.

There are no hard and fast rules, just guidelines depending how often you expect unwelcome guests, how restless is the electorate and if the peasants are revolting.

Modified by current and expected budgets, divided by procurement, maintenance, research and development, wages, pensions, and operations.

Sector Fleet gives a picture of Spinward Marches naval dispositions. Imperial and Reserve, and probably planetary.

 

[Reynard]

For a clue to the lowest tier on the interstellar military forces, here is a description about Colonial fleets for the Imperium from The Third Imperium: Sector Fleet supplement:

"The active vessels of the Colonial Fleet (i.e. those not ‘mothballed ‘ at naval depots) are owned and operated by individual
world governments, noble houses and corporate concerns. Any world is entitled to own and operate a star-faring navy,
though the operations of this navy are subject to regulations laid down by the Imperial Colonial Office once beyond the
immediate vicinity of the parent world."

"In addition to vessels maintained by member worlds, the Colonial Fleet gets its ships from two other sources. Squadrons
of obsolescent and obsolete warships are maintained at naval depots and manned by crews drawn from the Fleet
Reserve and Colonial Fleet. These include many capital ships which are beyond the means (and the needs) of most
worlds in peacetime, but which add greatly to the capabilities of the fleet in war.

In time of war, control of Colonial Fleet assets passes from the Colonial Office to the Navy. Colonial units are assigned to
the Sector and Subsector fleets, increasing their strength. They retain their ‘colonial’ designation but are commanded by
the Sector or Subsector admiral. Non-jump-capable warships remain under the control of their home system defense
command, of course."

This is the strategy of local protection in peace and war. The Imperium doesn't have the resources to patrol and defend the majority of their worlds with Sector and Subsector fleets. While colonial assets won't be individually as powerful, their numbers still make them a threat in all but frontline war.

The more powerful (richer) worlds don't rely on garrisoned jump fleets parked above. Defenses are a layered onion to pass through before invasion of the surface. Top layer will be both jump ships and more often non-jump ships - monitors, system defense boats, and other warship assets. It was either Pocket Empire or Imperial Squadrons that had a formula not only for locally produced warships but SDBs based on the wealth of the system. SDBs aren't just for sneak attacks. In support will be battle stations with the best available long ranged weapons and fighters and military small craft. Cheap manned and automated weapon platforms and drone mines (Traveller Companion) will form a ring before, alongside and behind the stationary assets. (COACC had an interesting design for an automated 120 dton medium missile bay that looks for the correct IFF). Once ships that survive pass to low orbit and the upper edge of the atmosphere they will face aerospace units built to take on small ships and landing units backed up by strategically emplaced batteries of aerospace defense lasers, missiles and other long ranged weapons. By the time troops step off they face ground opposition without full assets.

You have a fight on your hands.