MT Only: Planetary defense undetectable sensors

[Carlobrand]

Playing around with planetary defenses, came upon a curious feature of MT design: undetectable sensors. MegaTrav uses pinpoint sensors to gain a lock on targets to shoot at them. Pinpoint sensors include active EMS (basically radar and similar), densitometers, and neutrino sensors. The latter two are considered passive sensors - they don't emit anything you can detect, but instead try to detect something you're emitting. What this basically means is that of the three targeting sensors, two can't be detected. That's trickier at lower levels - TL13 and down sensors have a harder roll to lock onto the target. You get one free roll and a second if you have no weapons batteries; if you have weapon batteries, you can forego firing a weapon battery and get another roll. I don't think there's any limit on how many battery attacks you can forego. Once you have a lock, any of your craft can fire at that target, so if you have enough batteries to forego or enough independent platforms rolling that one scan, you start approaching a statistical certainty of a lock.

Per canon, deep meson sites can only be silenced by taking out their sensors: you roll as if they were a ship or boat, but only the sensor hits have an effect. That effect is to destroy one or more sets of sensors, attacker chooses type. However, as described you can't detect densitometers or neutrino sensors and - presumably - such detectors can be placed underground and the site camouflaged to look like any other patch of ground. You might find densitometers by scanning with your own densitometers - I suspect burying them any significant depth would interfere with their function - but a planet is a huge place; you're looking for a needle in a haystack. Neutrino sensors though, they can be as deep as the meson battery itself, which logically means they can't be silenced. They can also be used for passive scan.

That's a bit of a problem.

 

[kilemall]

Got you covered.

Meson guns are defended against by Meson Screens. They aren’t sensors per se, but by their nature they are going to interact with incoming fire and slow it down enough to hopefully ‘detonate’ short of the ship.

The screen therefore is interacting with the incoming particle stream and should be able to detect its direction and strength. It has to if only to reinforce the screen when under fire.

Not sufficient to get a target solution first thing as you likely won’t get depth finely enough from the strength. But as the meson guns fire, by comparing the line of each incoming shot vs different ships and presumably location, a picture emerges where these streams converge at the point of origin.

The other solution is to use the fleets neutrino sensors and destroy all the power plants.

 

[mike wightman]

Geothermal power plants.

 

[whartung]

Densitometers and neutrino detectors can't achieve lock. Fine for detecting, but not so much for targeting.

The big "problem" with deep meson sites is that they don't need "sensors". They need targeting data. Data that can come from anywhere. Surface installations, orbital installations, lunar bases, other ships, etc. Conventional artillery needs a map coordinate, they don't care how that coordinate is determined. Meson guns a point in space. They don't track fire like a machine gun or something, they discern where and when a target will be and make that point in time and space a very undesirable place to be.

Active sensors are going to get knocked out. The game is having more active sensors than the enemy can disable before the meson guns take their toll.

And, all told, sensors are cheap.

We just don't know how difficult cracking a planet would be on a wartime footing. We all know what irreparable harm a fleet can do to a planet, in a way a planet can do little about, raining rocks and nukes down on to the surface. So, is a planet with 100 unstoppable meson guns a "real" thing or no? I guess if you're trying to reduce an invading fleet as it passes through your sector, laying waste with no regard as it goes, then, maybe. But that doesn't seem very tenable from any perspective (outside of, say, Virus just being ticked at Carbon Based Lifeforms...).

"Mr. Saberhagen to the front desk please."

 

[Enoki]

I see this as a variant of the Flak / air defense system problem. The first problem is detection.

If you are limited to just a few means of detecting an enemy fleet moving in, to attack, then the best move for that fleet is to jam the living $4!+ out of your sensors. Against neutrinos, put out a screen of jammers that generate lots and lots of them, flooding the detection system. I'd think by TL 15 there's a way to generate them available. It would be like a hi-tech smokescreen. Sure, the defense knows you're coming and can be alert for your attack, but they can't predict your course, composition, or target until the jamming lifts, is imperfect (has gaps), or you move beyond it. In WW 2, the RAF did this against German air defenses using a jammer called Mandrel for example. Densitometers, same thing.

Since you are limited to the speed of light with meson guns and other energy and particle weapons, you have to predict where the enemy ship you're targeting will be when things arrive at their end. If the firing battery location and time it takes to get a fire control resolution are roughly known, the first line of active defense is to ensure you randomly, and effectively, change course within that action loop. That disrupts the OODA.

This means the defenders might well have to alter their tactics to account for this problem. It also argues that the best defense is a fleet of your own that goes out and attacks the enemy well away from your planet.

In fact, it might be better if defending planetary weapons, like the meson gun, fire a charge / round that has an area effect like an flak round, than expecting it to actually hit a specific ship in a fleet at say a million kilometers.

 

[whartung]

Since you are limited to the speed of light with meson guns and other energy and particle weapons

In orbit, this is not really a problem. Ships don't move, dodge, jink, or anything else at subsecond resolutions. Large ships can actually be "too big" to "get out of their own way". Aircraft have the advantage of control surfaces to make minute, quick direction changes. Spacecraft, not so much. They need to spin those hulls around to engage the main drive to make any kind of gross maneuver. All of that takes time, seconds, perhaps 10s of seconds, not a lot to us, but to light speed weapons and fast computers and sensors, it's an eternity.

Of course, this is manifest in B5 as DMs based on size, and configuration.

 

[kilemall]

Geothermal power plants.

Works for earth and other hot metal core planets. Thinking quite a few planets, aren’t.

 

[Enoki]

In orbit, this is not really a problem. Ships don't move, dodge, jink, or anything else at subsecond resolutions. Large ships can actually be "too big" to "get out of their own way". Aircraft have the advantage of control surfaces to make minute, quick direction changes. Spacecraft, not so much. They need to spin those hulls around to engage the main drive to make any kind of gross maneuver. All of that takes time, seconds, perhaps 10s of seconds, not a lot to us, but to light speed weapons and fast computers and sensors, it's an eternity.

Of course, this is manifest in B5 as DMs based on size, and configuration.

What fool of an admiral would attack from orbit. You start with stand-off weapons at a million kilometers or more from the planet. Then send in < 100 ton "fighters" and "bombers" in horde waves to decimate the defenses. If the planet is a "Magniot" planet, then take the rest of the system and lay siege to it. Lets see how long the defenders can hold out with zero resources...

 

[Carlobrand]

Densitometers and neutrino detectors can't achieve lock. Fine for detecting, but not so much for targeting. ...

While I would tend to agree that densitometers and neutrino detectors shouldn't achieve lock, at least so far as meson fire is concerned since it needs to correctly determine range as well as bearing, it remains that MT rules as written say they can achieve lock, unless there's been some revision in errata. Per the Referee's Manual, a TL14 HP Densitometer shows a passive object pinpoint difficulty of Routine, as does the TL14 10 Kw Neutrino Sensor, which is the same as the Far Orbit EMS Active Sensor. Later, the rules say the referee should use the most favorable sensor pinpoint difficulty to lock onto a target. I don't know about. I have no idea how they work in other versions of Traveller.

If the planet is a "Magniot" planet, then take the rest of the system and lay siege to it. Lets see how long the defenders can hold out with zero resources...

I think most planets powerful enough to be "Maginot" planets are going to have a heck of a lot of resources down on the planet itself.

 

[TamsinP]

Huh? How can a densitometer scan passively?

 

[mike wightman]

Universal Gravitational Wave interaction...