Passive Planetary Defenses

[Garnfellow]

DGP's World Builder's Handbook has a nice, short section on planetary defenses on page 96. Active defenses, namely deep meson gun sites, have been discussed in a few different threads here. But I'm interested in the passive defenses:

Passive defenses center on major population concentrations, and take the form of damper projectors and large (city-sized) meson screens. The atmosphere of a planet itself provides an effective shield against long-range laser and particle accelerator fire.

What would be the TL of planetary defense-scale damper projectors or city-sized meson screens? Have these been detailed anywhere else?

 

[flykiller]

well, hg2 specifies no particular size limit on screen sizes, so long as appropriate energy points are available. so, the tech levels involved would be the same, starting at, what, tech 12?

nuclear damper screens energy point requirements are fixed, so I imagine the device is a projector rather than a general screen.

 

[Condottiere]

I'd imagine that technological level twelve megacities would import the best possible defences they could afford.

 

[flykiller]

I'd imagine that technological level twelve megacities would import the best possible defences they could afford.

if the setting permits it, sure. if cost is the only issue then I'm sure they could afford anything available anywhere.

with limits, of course. I'm sure zimbabwe could buy some f16's, but operating them ... might be an issue.

 

[Enoki]

I'd think this depends a lot on how likely the given world is to be attacked. You don't see the US for example building bomb shelters everywhere when there's little real threat of a strike against the nation.
Why would some world in a "safe" location deep within the Imperium, for example, be wasting piles of cash on civil defense measures that in all likelihood will never get used?

As for places that are threatened, there are several approaches:

The first is to concentrate the means of defense. Large public shelters, organized defensive weapons emplacements, etc.

An alternative is to disperse the measures. Build smaller shelters everywhere, maybe less effective each but in such large numbers that most of the population will survive. Place other defenses as necessary for local protection but don't try to protect everything.

Then you might try to use camouflage and decoys to deflect attacks onto non-target areas instead, or make it difficult to find targets.

I'd also think what the attacker's motives were in terms of destruction. If their goal is virtual elimination of the planet's population and economic ability that requires different measures than if conquest and occupation with most of the planet intact were.

 

[Condottiere]

While meson screen might be optional, nuclear dampers are probably mandatory.

You never know where those Rebellion fanatics will strike next and with what.

 

[infojunky]

I am pondering where the concept of atmosphere protecting a planet from orbital laser fire came from.

 

[Whipsnade]

LBB:4 Mercenary has battlefield dampers appearing at TL 13 while LBB:5 HG2 has the shipboard variety appearing at TL 12. Looking at the battlefield version could give you some ideas regarding planetary defense installations.

The battlefield version consists of a pair of projectors mounted in vehicles along with either dedicated a targeting/acquisition system or one shared with artillery/rocket batteries. Depending on a ratio which varies by TL, the distance by which the projectors are separated translates into the area covered.

A planetary defense system would conceivably involve many more projectors separated more widely with a more extensive targeting/acquisition system.

 

[flykiller]

LBB:4 Mercenary has battlefield dampers appearing at TL 13 while LBB:5 HG2 has the shipboard variety appearing at TL 12.

the battlefield version is mobile. there's no reason for a city defense system to be mobile.

 

[Garnfellow]

LBB:4 Mercenary has battlefield dampers appearing at TL 13 while LBB:5 HG2 has the shipboard variety appearing at TL 12. Looking at the battlefield version could give you some ideas regarding planetary defense installations.

The battlefield version consists of a pair of projectors mounted in vehicles along with either dedicated a targeting/acquisition system or one shared with artillery/rocket batteries. Depending on a ratio which varies by TL, the distance by which the projectors are separated translates into the area covered.

A planetary defense system would conceivably involve many more projectors separated more widely with a more extensive targeting/acquisition system.

Good find. The MegaTraveller Referee's Companion has at TL 14 "Sophisticated nuclear dampers enable virtually complete protection of entire operational areas against nuclear warheads."

(It also has at TL 11 "Meson guns are introduced as a non-mobile, deep-mounted planetary defense weapon and as a space vessel weapon." I had thought this would have been TL 12.)

 

[Quint]

I am pondering where the concept of atmosphere protecting a planet from orbital laser fire came from.

The only thing that comes to mind is the "thermal blooming" that gets mentioned in the Tom Clancy novel Cardinal of the Kremlin

D.

 

[flykiller]

I am pondering where the concept of atmosphere protecting a planet from orbital laser fire came from.

atmospheric water will attenuate it. how effective this is will depend on how powerful you envision lasers as being.

 

[TheDS]

I am pondering where the concept of atmosphere protecting a planet from orbital laser fire came from.

FFS mentions the attenuating effects of atmospheres on both laser and particle accelerators.

Most Traveller players already know enough about Astronomy to know that the atmosphere protects us from pretty much every wavelength of light other than visible and radio. What they might not realize is that unlike movie lasers, Traveller lasers are likely to use frequencies of light which are a great deal more efficient than those, so for example, you'd prefer to use a UV laser because it offers significantly improved range performance over visible light. X-Ray lasers offer stupendous range performance! But they're not good in an atmosphere.

Likewise, atmospheres tend to disturb particle streams, which are made of magnetically neutral particles (think hydrogen atoms). However, there's a cheat: you can used charged particles (think protons) instead, and as they interact with the atmosphere, they create a magnetic pinching effect which holds the beam together; not as well as a neutral beam in space, but a hell of a lot better than a neutral beam in an atmosphere.

In game, these effects are represented with atmospheric range effects, which quickly attenuate damage and penetration. You can, of course, mount visible lasers and C-PAWs, but you really need to get a lot closer to use them; may as well put them on an atmospheric craft and gain the advantages of maneuverability. Meanwhile, your ortillery should be in the form of mesons or rail guns or missiles (oh my!).

 

[Enoki]

One way to neutralize to some extent the effect of lasers in an atmosphere is the same as allowed in the game in space: Sand. Simply put up a cloud cover of smoke made of particles that will diffract the beam, scattering and absorbing it.
It would actually work better in an atmosphere as it would remain in place for a relatively long period.

Against charged particles one could, at the simplest, create local powerful magnetic fields to interfere with them.

 

[infojunky]

It was less a Scientific pondering and more a 180 degree turn in assumptions as based in the rules, or at least CT. As ground based Laser Turrets were a thing in Book 2.

One way to neutralize to some extent the effect of lasers in an atmosphere is the same as allowed in the game in space: Sand. Simply put up a cloud cover of smoke made of particles that will diffract the beam, scattering and absorbing it.
It would actually work better in an atmosphere as it would remain in place for a relatively long period.

I actually like this one and probably will keep it is the toolbox....

Against charged particles one could, at the simplest, create local powerful magnetic fields to interfere with them.

Now remember that the assumption for particle beams that any atmosphere is a sufficient defense.

 

[Xerxeskingofking]

It was less a Scientific pondering and more a 180 degree turn in assumptions as based in the rules, or at least CT. As ground based Laser Turrets were a thing in Book 2.





I actually like this one and probably will keep it is the toolbox....



Now remember that the assumption for particle beams that any atmosphere is a sufficient defense.

the atmosphere as a defence is based on the assumption that the incoming beam is coming though the whole atmosphere. A ground based laser could provide point defense on a base site against, for example, a landing ship or incoming missiles.

 

[Otto Harkaman]

How about space stations, satellites, maybe outposts on asteroids? I am sure there is a layered defense, depending on the atmosphere would be the last resort if I was the Minister of Planetary Defense. :coffeecup:

Passive defense makes me think also of detection devices. Its obvious a lot of damage can be done to a planet by flinging an asteroid or sending a spacecraft at a super high velocity at it. I would imagine there are detection space buoys far out to monitor anything.

 

[AnotherDilbert]

Passive defense makes me think also of detection devices. Its obvious a lot of damage can be done to a planet by flinging an asteroid or sending a spacecraft at a super high velocity at it. I would imagine there are detection space buoys far out to monitor anything.

Exactly, what use are nuclear dampers when a 3 tonne (~1 m³) rock dropped from orbit has the impact energy of a small nuke?

If an enemy fleet is willing to terror-bomb you back to the stone age, they can. The major powers might not want to risk the inevitable reprisals.

 

[Carlobrand]

...If an enemy fleet is willing to terror-bomb you back to the stone age, they can. The major powers might not want to risk the inevitable reprisals.

The far future equivalent of Mutually Assured Destruction.

 

[Whipsnade]

The far future equivalent of Mutually Assured Destruction.

That's been the - unpalatable to some - "answer" to the problem of near-c rocks for decades now.