Planetary defense is a bit of a headache. It is at the same time cheap and hard to kill. A PD meson installation does not require drives or armor and only requires power enough for its gun, so more bang for the buck. The gun itself, and likely the crew serving it, are invulnerable to attack from space. Likely the computer is too, though surface sensors are vulnerable. The power plant might be vulnerable to attack based on locating it from its neutrino emissions, but that same argument makes ships vulnerable to attack from the PD installation using sensors that can't be detected or attacked, and fusion plants can be constructed as many small plants scattered over a wide area to reduce their vulnerability, something ships can't do. How would a fleet silence PD batteries other than by landing troops, and how would it support landed troops without the support getting blown up as it approached the planet?
Planetary defense
- Thread starter Carlobrand
- Start date
In CT, detection range is something like 300,000 km while tracking range once detected is like 900,000 km. So Fighters positioned 300,000 km from the planet can locate the Deep Meson Gun, while taking fire from it ... yet the FLEET can fire on the planet, DMG and enemy Defense Force from ranges that deny the planet any chance of detecting the fleet to get a target lock on it.
In the "there is no stealth in space" universe, you simply glass the ball of rock from far, far away ... congratulations, the DMG "won" the battle and lost the war.
In the "there is no stealth in space" universe, you simply glass the ball of rock from far, far away ... congratulations, the DMG "won" the battle and lost the war.
Timerover51
SOC-14 5K
Which is why I argue that planetary invasions are not exactly a good idea.
Several points here:
The MG sites are not,as you say, invulerable, at least to meson fire from space, as the MG can pass through any matter. The main point here is detecting them with enough exatitude to fire them (though probably a near miss would have some effect, be it due to EMP, radiation, damages on power gird or collapsing of part of the tunnels.
In both cases, I think rules refer to detection, not to pinpoint with enough ecxatitude to make them MG targets. Remember MG fire must be quite accurate on the specific point it makes the mesons decay, so it must aim a speciic point, not just a direction, as most other weapons.
And you're probably right in that it would be a true nightmare, but they may be in some cases necessary (aside from being interesting from he gaming POV).
OTOH, as most planets in OTU are relatively low population ones (among hundreds of thousands and a few millions) and lower TL than the Imperial troops, the planetary invasions are a true possibility with relatively few troops, and their capacity to build DMGs is limited.
Timerover51
SOC-14 5K
If you have a population for a planet of in the hundreds of thousands to a few millions, population 5 or 6, that is a different story. You can always land where there are not a lot of people, set up a base, and proceed from there. Basically the island hopping campaign in the Pacific, trying to land where the Japanese were weakest. That got tougher the closer to Japan though.
Detection is two light-seconds, but that's a quibble. More on point, how precisely are the fighters detecting the meson batteries?
On a semi-related note, I wouldn't as a gamemaster allow missile fire on a planet-side target in atmosphere from three light-seconds off. If missiles could survive re-entry at those speeds, they wouldn't even notice laser fire. Conversely, if they slow down to manage a re-entry, they're sitting ducks for defensive fire from the planet. Even if they could, having a ship pick out a specific target against the surface of a planet from three light-seconds off is not the same as picking out a target against the background of space. Always figured the reason Invasion Earth required ships on bombing runs to be in close orbit was because the missiles either wouldn't survive re-entry, would get shot down if moving slower from farther out, or the ships wouldn't be able to distinguish targets against the background of a planet's surface from farther out. I also wouldn't let a ship get away with firing weapons while remaining undetected, even at three light-seconds. But, other people may have different views.
And, from Striker Book 2: "The most common form of active defense in the deep meson gun site. A deep meson gun is a meson gun of ship ordnance size buried in a deep underground chamber. As the planet itself is transparent to the meson beam, the meson gun can fire at any target desired, while the site itself is effectively impossible to locate. Only when the gun site's surface sensors and target acquisition devices have been destroyed or captured can the gun be silenced, this generally requiring the use of ground troops or extensive planetary bombardment."
MegaTraveller followed through on that theme. EM sensors aren't going to detect something buried deep in a planet, and densitometers go to 1 Km at TL15; below that depth, you couldn't detect anything except neutrinos, which means the power plants are vulnerable but the buried guns aren't.
See response above. One cannot hit a target if one has no idea where it is. I can argue for eroding the power supply, and I'd have to develop rules for locating and destroying sensors if I were inclined to model such a combat, but the gun itself is pretty much impossible to find unless your intelligence agents managed to learn its position.
Depends on tech level, which model you're using for GWP, and a couple other starting assumptions, but I'm getting in the vicinity of 300 thousand or so population as the minimum to afford a single installation at TL13. At that it's eating up 15% of GWP annually, so it's most of a planet's military budget. Less at TL15 because of the higher per capita GWP and cheaper power. Gets rather expensive before that, between the lower tech systems and the lower per capita. Mind, it's a good investment if the point is to keep people from threatening your cities with nukes from orbit, but it's a pretty heavy tax burden; whether it's worthwhile or not is likely to depend very much on local circumstances.
Enoki
SOC-14 1K
I would think that a serious planetary defense system would be nearly impossible to beat head on.
First, powering the defenses would be of little difficulty. You could use a mix of dedicated sources and tie the defenses into the planet's grid as well. That would give near unlimited power to the weapons for all intents. It would also make taking out their power supplies very hard to do.
The fire controls could be placed off planet as well as located with the battery to give more than one means to target things. Satellites or even stations on moons or other nearby objects could be used, linked by various communications means, to ensure that targeting is always available.
If the planet has moon(s), these too could be worked into the defenses as additional positions making it harder to take any one of them out.
I would think that an attacker would focus at first on degrading or eliminating the targeting systems for the planetary defenses. I'll leave it to imagination how that could be done. Some suggestions might be:
EMP weapons to degrade electronic sensors. Spreading "sand" in the path of the planet's orbit and waiting for it to enter the cloud before attacking.
Laying siege to the system is an obvious tactic, assuming that the system isn't self sufficient in terms of basic needs of the population.
First, powering the defenses would be of little difficulty. You could use a mix of dedicated sources and tie the defenses into the planet's grid as well. That would give near unlimited power to the weapons for all intents. It would also make taking out their power supplies very hard to do.
The fire controls could be placed off planet as well as located with the battery to give more than one means to target things. Satellites or even stations on moons or other nearby objects could be used, linked by various communications means, to ensure that targeting is always available.
If the planet has moon(s), these too could be worked into the defenses as additional positions making it harder to take any one of them out.
I would think that an attacker would focus at first on degrading or eliminating the targeting systems for the planetary defenses. I'll leave it to imagination how that could be done. Some suggestions might be:
EMP weapons to degrade electronic sensors. Spreading "sand" in the path of the planet's orbit and waiting for it to enter the cloud before attacking.
Laying siege to the system is an obvious tactic, assuming that the system isn't self sufficient in terms of basic needs of the population.
kilemall
SOC-14 5K
Stealing plans and locations of the defenses, internal saboteurs planted, hacking control systems are all non-frontal assault ways of dealing with planetary defenses.
Building on this, finding these defensive positions in peace time will be a priority mission for any Naval Service and their construction will be registered in several locations between the contractors, local defence, local government and fleet defences. In the case of large empires add in sector and central government agencies.
Other vulnerabilities include supply chain considerations, supplying people, spares, food, upgrades, etc. The power source in peacetime, which might use thermal energy (no neutrinos emitted), might also be used to supply nearby cities or industry. The specialist crew, while not large, may also not be overly subtle in enjoying their elite status in the local defense hierarchy, locating where they spend off-duty time may not be difficult.
Training exercises may also provide useful intelligence and could be monitored using autonomous passive sensors. Training may also involve defense elements outside the deep meson team, for instance local ground forces tasked to defend odd locations with little perceptible defense value. SDB units working in concert with ground based defensive fire.
The gold is the rough location of the deep meson site. Once this is established, that information will be good for decades.
Of course that leads into counter-intel operations, leading offensive intel to believe they have the gold...
"They blew up Cheyenne Mountain! Hah! We haven't used that since we let that TV show film there!"
From what I recall meson guns cannot be tracked, so if you buried one under a mile of rock it's essentially unhittable except by other meson weapons. But it's also entirely blind on it's own. I would think it would be impossible to take out all planetary sensors because even passive ones would give you a good view of attacking forces, enough for you to feed to your meson sites. Plus EMP blasts would be useless against mil-spec gear. All you are doing is frying civilian electronics - ones you probably want intact if you want the planet intact.
Power-wise a big planet would have so many neutrino sources it would be near impossible to detect them all - unless you had some device that could pinpoint all of them, and I don't think that would fall within the Traveller tech concepts. And there's always hydropower, geo-thermal, even fission, that could be used.
Planetary invasions are supposed to be horrible and hard. Which is why you want to get your troops down on the ground as fast as possible. Ships in orbit at least have meson screens to help defend against the sites.
Power-wise a big planet would have so many neutrino sources it would be near impossible to detect them all - unless you had some device that could pinpoint all of them, and I don't think that would fall within the Traveller tech concepts. And there's always hydropower, geo-thermal, even fission, that could be used.
Planetary invasions are supposed to be horrible and hard. Which is why you want to get your troops down on the ground as fast as possible. Ships in orbit at least have meson screens to help defend against the sites.
Enoki
SOC-14 1K
Since meson communications exist, it would be easy to put the fire controls for a meson weapon off planet such that you'd have a near impossible time detecting them and they could send the firing crew all the data they needed to aim accurately.
Worse, the defense could easily distribute active sensor systems such that the component parts are numerous, redundant, and widely scattered making it impossible, or nearly so, to take them out.
Worse, the defense could easily distribute active sensor systems such that the component parts are numerous, redundant, and widely scattered making it impossible, or nearly so, to take them out.
This has always been my perspective. These are strategic assets, and while they can be kept secret, it's kind of hard to do so. Also, the meson guns mounted on starships are REALLY big. Their blast radius is substantial, compared to the ground based ones mentioned in Striker.
Yea, but they don't really comment on how much easier it is to hit planet based stuff in contrast to starships. Much of the "to hit" logic in the game is based on tiny target and far ranges moving at high velocities. Yes planets move at high velocities, but it's vector is well set -- unlike starships. So, I think there should be a large DM for "nuking sites from orbit" than simply "it's 500Kton + sized starship".
The two hard problems with deep meson sites is a) locating them, and b) penetrating their meson screens.
But if you know with any certainty where they are, then, it's really just up to the meson screen. Once through that, though, "It's dead Jim - one shot, one kill". Mechanically, I would not roll "to hit" against a PD Meson Gun. I'd just roll to penetrate.
If you DON'T know where it is, or you know where, but not how deep, then it's recon by fire. Not sure what happens when a 100m radius meson blast goes off 125m below the ground. Collapses all tunnels, does it shatter bedrock? Do construction firms use meson guns to soften up areas to dig deep meson sites?
How deep would a meson site need to be to be resistant to "bunker busting" nuclear weapons?
For what I know, those shown in Stiker are mobile ones, as SP artillery. The DMG are as large as any ship's one.
In Assignement Vigilante, IIRC, the one they find is rated as T.
That's my take too, and intelligence, by any means, is the critical factor here. If they are ever located, remember they cannot be moved.
I guess most DMG are over 1 km under the earth crust, just to avoid hiPen densiometers (according MT, at least). I guess that's deep enough for most (if not all) "Bunker busting" nukes...
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mike wightman
SOC-14 10K
You should be able to detect a meson screen from its interaction with a meson comm broadcast...
If you're using MT, detecting and pinpointing isn't an issue, assuming enough spacecraft with detectors and good computers. They can't and won't discriminate between civilian and military sources; they need to silence as many power sources as possible to silence the guns. Numbers would be a problem if the world is big enough and the power plants sufficiently small and dispersed.
Striker Book 2: "Meson guns have a burst radius equal to their High Guard ratings in cm, with A counted as 10, etc." So 270 meters for a T.
It's not as hard to hide as you'd think. Certainly spies could pick up the entrances, but the precise underground position could be hidden by varying the angle of the dig. Change out the workers at key stages, design the elevators that bring miners (and eventually personnel) down so occupants can't guess at the rate of descent - equip them with grav generators and inertial dampers and the occupants won't even know the direction they're going - and the only people who know are the engineers who design it. If those are brought in from off-planet, just finding out who knows could be a major espionage effort. Design the actual chamber as a shell game with several chambers that the gun can rotate through, and even knowing the location doesn't ensure they can knock out the gun.
This assumes planet-based stuff is fixed and of known location. One thing that's pretty clear in the future military setting is things need to be mobile if they don't want to get nuked. Deep meson sites can be hidden. Sensors are vulnerable but likely also mobile. Fusion plants are vulnerable but can be buried against nuclear attack and made small and dispersed so meson attack degrades the power net only slowly. In a culture with thousands of years of experience of war in space, it may even be the custom to place all war manufacture industries and even power sources away from urban centers and in deep bunkers, to minimize the danger to civilian populations. They might perhaps even make some vital factories grav-mobile, little different from spacecraft in fact, so they could move away from approaching enemy troops or go hide in the sea to escape bombardment. The strategic combat environment starts looking very different if you use all the tools available.
Invasion Earth, in addition to its fixed PD installations, presented mobile PD installations which acted a lot like SDBs/battleriders designed to operate from the ground and protected by a regiment of troops, probably more vulnerable to attack from space but able to move away from approaching enemy troops.
I'm really struggling with meson screens for planetary defenses. Their usefulness is marginal against big guns but they'd stop any bay mesons and would seriously impair the performance of light-cruiser mesons, which would force the bigger ships to come in and expose themselves if the enemy wanted to bring mesons to bear to reduce the PD installation. For a ship, one unit covers the ship with the power needed determined by the size of the ship, which in the context of a ground installation presumable means the volume to be protected. Multiple dispersed volumes - the dispersed power plants - would presumably each need their own unit (much as multiple ships would), which can get expensive. Or, I could do something like use a single unit to create a field big enough protect all of them (and the volume of empty space between them), which really ratchets up the power needed, which means a big investment in power plants to power the meson screen. It approaches a point where it makes more sense to put in a second gun rather than investing in a meson defense, whether it's from the cost of all those meson screens or from the cost of the power needed by the one meson screen covering the large area.
Build a large (500 km or more) grid of deep tunnels, with blast doors and multiple meson guns that can move between sections of tunnel. Sensor sites use meson communicators to fixed repeater sites that then use optical fiber to distribute the targeting data to the meson guns. (meson communications direct to a gun is a Bad Idea, capture the sensor and you get the gun's position) each repeater services a single sensor platform.
Power systems: banks of accumulators charged in peace time able to support the operation of the gun for months to years. If you're willing to spend the money you can have a really hard to eliminate deep meson defense complex. Oh and crews? the guns themselves are not crewed or they are crewed but the crews are stationed there for life. (Some government types CAN do that). This would reduce the humit angle of finding the guns.
Power systems: banks of accumulators charged in peace time able to support the operation of the gun for months to years. If you're willing to spend the money you can have a really hard to eliminate deep meson defense complex. Oh and crews? the guns themselves are not crewed or they are crewed but the crews are stationed there for life. (Some government types CAN do that). This would reduce the humit angle of finding the guns.
Just some questions:
Many talk about detecting the power sources by the neutrinos, but what about non-neutrino generating ones, like solar, geothermic (quite useful, I guess, for underground facilites), etc. Could they be so detected?
Can meson screens be deployed in underground facilities? I know Nuclear Dampers may be used planetside (the vehiclesjust for that are told about in several groundunits descriptions in CT), and I guess Black Globes cannot (as matter will interfere with them1), but I've never heard about meson screens...
And what about DMGs being mounted in deep going submarines (should the world have such hydrosphere) so that they can be moved? How would ocean interfere with densiometers?
Many talk about detecting the power sources by the neutrinos, but what about non-neutrino generating ones, like solar, geothermic (quite useful, I guess, for underground facilites), etc. Could they be so detected?
Can meson screens be deployed in underground facilities? I know Nuclear Dampers may be used planetside (the vehiclesjust for that are told about in several groundunits descriptions in CT), and I guess Black Globes cannot (as matter will interfere with them1), but I've never heard about meson screens...
Note 1: I've read in another thread about T5 talking about a Marine Base protected by a BG, but T5 must have retconned the BG, as this seems against most what was said on them in previous versions
And what about DMGs being mounted in deep going submarines (should the world have such hydrosphere) so that they can be moved? How would ocean interfere with densiometers?
