Invading Star Systems/Defending Them

[Raynulf]

I would think that in any vital system a large scale 'wall of defences' would not be used, but rather key resources/ points would be heavily defended.

A system contains only a handful of planets and usually a large number of small asteroids. Hidden mine dispersal facilities among moons, asteroids and planetary rings are a given, making such regions hazardous for ships to enter.

Many people have suggested jumping to a region behind a gas giant and mustering/refueling. The solution to this appears simple. Defend the gas giants.

Multible small, deep atmosphere stations, armed with 'conventional' and nuclear missiles and guided mines will inflict horrendous casualties on oncoming fleets, especially if they are attempting to use the planets shadow as a muster point. They will also notify the system defences of the enemy fleet as it arrives. Even on a small scale such installations would render it unfeasible to try to use local resources to refuel, forcing enemy fleets to bring sufficient fuel with them for the jump in, prolonged combat and emergency jump out (aka withdrawal).

Defend the things worth defending and don't give your enemy in-system hiding places.

 

[savage]

The enemy fleet probably wouldn't have that intel.

IMTU gas giants are defended. And it can be deadly
to have 20 meson guns open up on incomming ships trying to refuel.

Savage

 

[Raynulf]

"Incoming fleet wouldn't have that intel"

What intel? I'm assuming this was in response to my post.

My assuption was that the incoming fleet would have limited knowledge of the defenses in place, however it would likely have some idea as to whether or not things would be defended.

Take roid belts, for example. A large number of variously sized obect floating in orbit of the sun. It is relatively easy to place some nuclear mines, missile platforms and the odd meson cannon amongst them. Inpenetrable? No, since space is 3D and you can just go over them, making massive defensive facilities impractical since they can be avoided.

Roids also have little short term strategic value. Gas giants however do, and are far easier to defend than a vast stretch of space.

 

[savage]

Raynulf,

I was agreeing with your assumption of defending the gas giant(s) but there is no reason to assume an enemy fleet is aware of the defense being in place.
This causes an issue. If they attack the world before the gas giant those defenses will not be as useful...afterall suprise is an important factor.

Also, once we let them roam about the system it might be very hard to ever get rid of them. They
could leave spies at key locations... etc.

Savage

 

[Typhonis]

Hmm where are the mine rules? and couldn`t you design say a 50Dt vehicle to do the same thing((remeber the Centauri barrier mines from B5?))

Simply have it scan for IFF codes if they don`t match the computer has the thing wait till gravity has a good hold of the target craft then it opens up while sending an alert to the local military

 

[RainOfSteel]

Originally posted by Typhonis:
Hmm where are the mine rules? and couldn`t you design say a 50Dt vehicle to do the same thing((remeber the Centauri barrier mines from B5?))

Simply have it scan for IFF codes if they don`t match the computer has the thing wait till gravity has a good hold of the target craft then it opens up while sending an alert to the local military

What does the mine do if no IFF is being broadcast? Does it do its own scans, announcing its location?

Also, can you further explain how the mine would deliver its ordinance?

 

[Typhonis]

It would use passive sensors to determine if a target craft is in the area nothing that broadcasts its presence .IFFs transmit cinstantly if I remeber correctly so it only needs to recieve the correct data as for puting steel on target it could simply launch a spread of missle at said target ,most missles have there own guidance I believe))or a more advanced model could have a laser turret course once it locks and fires it dies you`ll only need about 30 shots for the lasers

 

[The Oz]

Military vessels do not continuously broadcast their identity, either today or in the world of TRAVELLER. The transponders on military craft today will only respond to properly coded transmissions (this is the IFF function), this way you can't get them to give themselves away with a random radar hit.

I can't see things working any different in the game. Military ships have ID transponders which can be shut down, which can reply with false IDs, or which can be set to only respond to queries from other friendlies.

However, it's still possible to have mines. There are ways to identify a non-cooperative target, even with passive sensors. It usually takes longer (you need more time to gather the data) and is less precise, but since you'd only be deploying mines in wartime the benefit of using mines is probably worth the occasional loss of a ship or two of your own. Losing friendly ships in friendly minefields is a long-standing fact of war.

 

[Typhonis]

True and the simplest mine may be a large AS missle say 1 DT with a robot brain and passive sensors deploy them near targets or along expected Jump paths friendly civilain ships will not be molested since they may transmit IFF all the time and if placed to interdict fueling they will have an hour or so to determine friend or foe status .

 

[MrMorden]

I haven't read the entire thread (9 pages!) so this may have already been brought up:

You don't have to destroy deep meson gun sites. You destroy their surface fire control sensors. Once they're blind they can't effectively hurt you. The sensors will be broadcasting, since passive EM sensors won't get through the atmosphere. Neutrino sensors can be located and destroyed by waves of small craft.

Plus, there are always meson screens.

 

[Anthony]

Passive EM sensors get through atmosphere just fine. The problem with taking out the sensors is that you can have quite a lot of sensors for any given meson gun, one sensor can provide firing solutions to multiple weapons, and it's a pain when you have troopships landing on the world and they suddenly trundle an extra set of targeting sensors out of a garage somewhere and the troopships start blowing up.

 

[MrMorden]

Heh, point taken.

However, I do think passive EM is not a good choice on a planet with an atmosphere. IR attenuates badly in atmosphere, especially if there is a lot of water vapor present. And microwave range signals assume your targets are emitting. If do don't want a bunch of ships to run silent and slip into low orbit, you're best off with active EM or neutrino sensors.

IMO, of course!

 

[Anthony]

Originally posted by MrMorden:
Heh, point taken.

However, I do think passive EM is not a good choice on a planet with an atmosphere.

You do realize that optical sensors are passive EM? Optical sensors are perfectly effective from planetary surfaces.

 

[Rupert Boleyn]

Originally posted by MrMorden:
I haven't read the entire thread (9 pages!) so this may have already been brought up:

You don't have to destroy deep meson gun sites. You destroy their surface fire control sensors. Once they're blind they can't effectively hurt you. The sensors will be broadcasting, since passive EM sensors won't get through the atmosphere. Neutrino sensors can be located and destroyed by waves of small craft.

Plus, there are always meson screens.

What if the sensors consist of thousands of small (satelite TV or amateur astonomer telescope sized) sensors scattered across the planet and connected to all the meson guns via the local internet? A proeprly design net is hard to destroy (especially if you want to use the planet yourself), and the sensors and guns can be anywhere, and replacements can be plugged in anytime.

Easier to provike attacks with a heavily screened ship (preferably one without much value or crew) and track back to the gun from the meson shot.

 

[mike wightman]

Question. Any ideas how to track back a meson shot? It could be a function of the meson screen and main computer but are there other ways?

 

[Rupert Boleyn]

Originally posted by Sigg Oddra:
Question. Any ideas how to track back a meson shot? It could be a function of the meson screen and main computer but are there other ways?

Nothing's mentioned in canon, though it seems likely that there'll be some sort of firing signature - they're exactly low-energy devices.

IMO the burst pattern from a meson gun is likely to have a distinctive shape that will depend on range, weapon model, etc. Using the observed characteristics of the burst and it's size (it'll be more dispersed at long ranges) it should be possible to calculate the area the shot came from. Obviously the more shots you observe the more accurate your location will be. Also, it's likely the defenders will have multiple guns of the same make, model, and year, and put at least some close (but not too close) together and fire them in a random order so that it looks like the same gun's firing but it's actually not.

 

[The Oz]

Originally posted by Sigg Oddra:
Question. Any ideas how to track back a meson shot? It could be a function of the meson screen and main computer but are there other ways?

I've always held that a meson gun burst will be essentially linear. What you get is a line of explosions in space as the mesons decay, with most of the explosions occurring at the point the burst was meant to decay, but some mesons will decay early or late, forming the line of explosions. This line should point back to where the meson gun was when it fired the burst. Don't forget the meson gun will have moved a bit while the burst travelled to the target, not much but a little. Even a Deep Meson Gun Site (DMGS) will have moved a bit as the planet rotates and orbits around its primary.

The trouble is that you don't know where along that line the meson gun is. This is not a problem for ship-mounted guns, as the gun is obviously in the ship. But for a DMGS the "line of fire" (and it would have been a "line of fire" as those mesons decayed) will extend through a big object and you need to know just where inside that planet to aim your own meson burst.

If you can get two or more bursts from the same DMGS weapon (I'm assuming that the burst of any weapon is individually distinctive, which it might be or might not be) you could cross-correlate the "lines of fire" from the multiple bursts with the motion of the planet and so effectively triangulate on the rough location of the DMGS. The more bursts you get from the same weapon the faster and more accurately you can do this. Of course, surviving those multiple meson gun bursts could be no fun at all....

 

[savage]

Passive sensors don't necessarily have to be on the planet. If it has a moon or other bodies, initial sensor readings can come from those locations as well. If one can track for 2 parsecs this becomes a minor issue.
If your going to the expense to build DMGs there are a few things to be certain you do.
1. Allow the MG to rotate positions.
2. If there is a way to track it add in a rail system for limited movement. It needs to be difficult to track for about 1/2 hr of live fire.
3. Run the power off the planet via geothermal, if available.
4. Overkill on sensors. 1 sensor gets destroyed activate the 2nd then the 3rd...

I haven't seen any canon to support meson decay leaving a trail. This would make DMGs extremely dangerous to the populace of the defended planet.
If there were a trail it would have to be relatively brief to keep the weapon effective.

I'd say this calls for a good definition of meson weaponry.
I looked quickly and found a couple things;
1. MT says communicators are non-intereceptable it would be logical to assume the entire packet of energy emerges at one location not leaving a trail.
2. Communicators also do not need to re-aquire a target once the link is established. They do start the emission via sensor tracking.
3. TNE:FFS states that DMGs were used extensively during the final war. And that some of the last people on worlds were the DMG crews.
4. that meson's have a short life span and the decay span can be timed.
5. This makes armour useless. The decay is within the target unlike a particle accelerator.
6. The screens pre-maturely detonate the packet by causing early decay.
7. CT: High Guard mentions that damage occurs via explosion and radiation
8. CT: Striker mentions that 2 communicators require a battlefield computer with one of the to stay aquired if either is moving. We might extrapolate that. If the ship is not moving or is on a predictable course a meson system should be able to still hit the target without re-viewing sensor readings.
9. Everything mentions that mesons pass through matter without interacting with it.

I'd assume that if you had a trail you could intercept a meson communications. Since, you cannot I don't see justification for the trail theory unless you have another source?


Savage

 

[Anthony]

Originally posted by Savage:
Passive sensors don't necessarily have to be on the planet. If it has a moon or other bodies, initial sensor readings can come from those locations as well.

You want to minimize sensor delays; it would be hard to hit something near earth based on sensors on the moon because of a 1.3 second sensor lag.

 

[mike wightman]

Check the scales of the various Traveller ship combat systems and then compare to the Earth-Moon distance. It doesn't appear that a couple of seconds sensor lag affects tageting too much

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