The ultimate weapon

[Icosahedron]

Some of the following ideas have been covered already, but I was writing while I read.

The detection ranges quoted in Traveller are for solitary patrolling ships. One roving adventurer detecting another. There are other options.

Ships may have longer detection ranges if they are stationary, or silent, or both. They may extend detection ranges by working together to form a ‘virtual aperture’ network. There may be a static array of detectors that feed a planet’s military command. Such an array, linked to a deep meson site would probably remove the threat from a single incoming device, if not a good number of them.

Ships are designed to withstand/deflect ‘grain impacts’ at normal speeds. Once you start accelerating to ‘silly speed’, your ship is likely to hit grains that will tear it apart partway along its run - especially if the near-planetary environs have been seeded with sand specifically for this purpose.

These are passive defences. There are also active defences - space patrols, coastguards, etc, carrying out sweeps for jump-flashes, detecting inbound craft during the early stages of their run-up, intercepting or passing information back to Command to facilitate other intercepts. The automatic beacon that announces and identifies any civilian vessel as soon as it jumps in.

Then there is intelligence. Who have you spoken to while you were planning and preparing your attack? Who is buying up old small craft? What are they doing with them? An order for 10,000 1 ton ceramic balls - what are those for?Where did you fuel up? What was your flight plan? When did you deviate from it? A ship left system X bound for system Y on date Z, it never arrived, where is it now?

Then there is propaganda and community spying. Have YOU heard anything suspicious? It could be YOUR world next.

Then there is Black Ops Intelligence. If we had clairvoyants, which we don't, they might have ‘seen’ a world destroyed sometime next month, which they didn't. They might say there are five would-be perpetrators on planet Zargle, which there aren't. Your totally deniable mission, should you choose to accept it, is to find and eliminate these non-existent miscreants before their non-existent plan can unfold...

 

[Omnivore]

Very interesting ideas Icosahedron, the detection ideas make a great deal of sense, especially the 'virtual aperture' network. I also think you're on the right track with the intelligence angle.

With respect to grain impacts and seeding the near-planetary environs, problem is two-fold, first any intelligent attacker will use a trajectory that avoids the most dense area (the ecliptic plane), and second - once the inbound r-bomb is within a few seconds of impact it's too late - it will, by design, self destruct into many fragments as that gives a more effective attack. If it is an attack by an enemy military force, there will be dozens if not hundreds of the things inbound - they are extremely cheap compared to the target.

Trying to patrol the launch zone is also a bit of a problem - it is a spherical shell of between 250 and 1000 AU in radius depending upon the G-rating of the r-bomb.

However the biggest problem of all is in trying to get into position and hit the incoming r-bombs while they are still far enough out. Basic problem is they are traveling so fast that even if you can somehow get into a possible intercept position, by the time you see them, they are millions of km away from that point and even a small bit of evasive maneuvering makes hitting them so highly improbable as to effectively be impossible.

There is also the point that they'll only be in range for a few seconds at best - say 1/250th of a High Guard combat turn. Roll 3d6 for 18 to get a solid hit even if you are aiming in the right general direction where normal to-hit rolls would be applicable. But you won't be because their effective agility is off the scale.

From a defensive standpoint it is pretty much identical to the cold war period with submarine launched ICBMs.

Heh, just had the thought - what about using the relativistic bombardment vessel as a missile bus - idea not being to totally destroy the planet but to drop a few crowbars on strategic targets?

 

[BytePro]

From back when I cared to address such anomalies for game play - IMTU, high TL (and rich) worlds have a sphere of satellites in orbit inside the safe jump emergence boundary - less than 180 suffice around a typical size 8 world to provide under 1 light second separation. Wealthier ones have multiple layers of defenses.

(IMTU these exist for other reasons - routine defense and as I allow hot jumps where ships can have a decent relative velocity incoming.)

Even near-c impactors within CT limits are addressable - though the system could be over-saturated and, of course, targeted. An expensive system - that would be very effective against any single target (even most that 'separate' themselves) such as those launched by pirates and small organizations and most that are the merest fraction of c - but would, as any system is, be less effective against an expensive attack or a uniquely creative one.

Accelerating to frac-c, and especially, near-c is very time consuming in terms of CT accelerations - requiring a very 'clean' ramp up path many Neptune orbits long... not only a chance to temp self-obliteration, but also turning the 'weapon' into a nice cosmic ray collector (increasing odds of system failures).

IMTU, cosmic rays are one of the reasons ships need annual overhauls and routine repairs. In RL, traveling distances that take one outside the 'protective' confines of a solar system greatly increases cosmic ray exposure.

Another aspect of multi-week and multi-month ramp ups - it gives time for intelligence. The week jump delay, of course, neutralizes a bit of the value of such - but not completely.

So frac-c/near-c jump impactors, while not inconceivable, are generally a very expensive operation IMTU and are largely subject to failure prior to jump, not to mention they leave a huge trail (pun) of forensic evidence behind. Not really a good thing to be known for in one's galactic neighborhood (for a government or a pirate...).

[Borrowing from RL, there is Relativity to consider as well as exotic affects, like electron stripping, that could also be used for in-game damping ships accelerating to high-v... not to mention handwavium house rules.]

 

[Hal]

A couple of thoughts hit me while looking at the posts in the thread:

Per older Traveller material - it seems that jumps are not overly accurate. The one most recent document written by Marc Miller, was on the order of 3,000 km is the most accurate a jump can be - per parsec of travel. Toss in the time variable of +/- 10% for the standard 168 hour journey - and the question of "aimed directly for the planet upon jump space emergence" becomes a problem.

Why? Because planets are moving at some pretty fantastic speeds in and of them selves. Take Earth for example. Its 29.8 kilometers per second orbital velocity means that in the space of 3 hours, it will have moved some 321,840 kilometers from its original position.

So, the exit from jump space has to be accurate to begin with (ie with respect to location) and it has to be accurate with respect to the vector movement attempting an intercept plot with the planet. Then the jump emergence has to be accurate enough for the ship to actively hit the target.

As for detection ranges for jump flash?

It all depends on whether or not you believe that the Jump emergence or entrance creates a visual flash. THE STARSHIP OPERATOR'S MANUAL mentions a jump flash. If that isn't canon, then the issue of whether or not jump flash exists becomes a bone of contention

The next thing to consider is this:

These ships are supposed to be designed such that high velocity impacts at High C would be a "Bad thing". Wouldn't you expect that there would be safety overrides to avoid ships "accidentally" initiating a high C impact with a given world?

In addition to all of this - would you not expect that just as airports have approach vectors for landing and taking off at any given air port, wouldn't one expect that the starport authorities would make an effort to create order out of chaos when dealing with approaching star craft capable of pulverizing worlds even when NOT moving at significant fractions of C?

And last but not least: Would would be the effect of a vaporizing explosion on any mass moving through space? Would not the explosion act as a potential "reaction thrustor" against the object in question? Could a steady Meson Stream designed to impact on the surface of an object, act almost like mass driver of sorts - where the constant explosion and vaporization of the surface can act like a thruster? Just thoughts that run through my mind.

Keep in mind, all of this depends on advanced knowledge of an incoming ship. If moving at say, .8 C's - that ship had darn well better be aimed PERFECTLY, as a miss by a few miles is still a miss.

 

[Omnivore]

Rereading some of the posts leads me to believe some posters are missing a crucial bit. When using specially designed relativistic attack drones, the launching ship would not jump to 100D of the target world.

Instead, the launching vessel would jump to either empty space or a body of some sort (for Sol system something between Kuiper belt and Oort cloud). The jump exit point would be on the order of 100 light hours from the target, preferably a bit above or below the plane of the ecliptic.

Depending on the design of the relativistic attack vehicle, it would take between three and six months to reach the target. Obviously the attack vehicle would expend a small percentage of its delta-v on random trajectory variations. There would be no orbiting although the initial approach might look something akin to an extremely elliptical orbit around the system primary.

I hate to have to keep repeating the obvious but... there is no way to determine the absolute position at any time of a maneuvering object traveling at an appreciable percentage of light speed. You can only see where it was some millions of kilometers ago. Even if you are directly in its path, if it is maneuvering evasively at all, the volume of space enclosing its possible real positions is *huge*. By the time the trajectory narrows due to needing to hit the target, it is too late to hit it. Even if you managed to vaporize it, it would still deliver the energy to the target - just in a slightly different form.

Sigh... and I know there will be people reading this who just don't understand still, so this will be my last feeble attempt at explaining the physics involved.

 

[madmike]

Pretty much my take on the issue as well.

The launch ship jumps in (well outside the inner system) then launches the "rock" after the system is scanned and an appropriate course is plotted.

If the "rock" is launched at 2G, it would accelerate very rapidly as it "fell" into the gravity well of the star, on towards the easily computed impact point of the target.

"The Lost Fleet" series by Jack Campbell uses kinetic projectiles for long and short range bombardment. Capital ships firing HSKP rounds or "rocks" whilst in the outer edges of systems to kill orbital facilities and ground targets.

I decided several weeks ago that I was going to use jump points as opposed to a ship simply jumping in at any location within to a destination system.

 

[Hal]

Rereading some of the posts leads me to believe some posters are missing a crucial bit. When using specially designed relativistic attack drones, the launching ship would not jump to 100D of the target world.

Instead, the launching vessel would jump to either empty space or a body of some sort (for Sol system something between Kuiper belt and Oort cloud). The jump exit point would be on the order of 100 light hours from the target, preferably a bit above or below the plane of the ecliptic.

Depending on the design of the relativistic attack vehicle, it would take between three and six months to reach the target. Obviously the attack vehicle would expend a small percentage of its delta-v on random trajectory variations. There would be no orbiting although the initial approach might look something akin to an extremely elliptical orbit around the system primary.

I hate to have to keep repeating the obvious but... there is no way to determine the absolute position at any time of a maneuvering object traveling at an appreciable percentage of light speed. You can only see where it was some millions of kilometers ago. Even if you are directly in its path, if it is maneuvering evasively at all, the volume of space enclosing its possible real positions is *huge*. By the time the trajectory narrows due to needing to hit the target, it is too late to hit it. Even if you managed to vaporize it, it would still deliver the energy to the target - just in a slightly different form.

Sigh... and I know there will be people reading this who just don't understand still, so this will be my last feeble attempt at explaining the physics involved.

The only thing I will add to your points raised above are:

A) vector movement being what it is - you have to account for not only where the impactor is at any given moment, but also where the target of the impactor is at any given moment. Here's the problem with your statement about not knowing where the impactor is at any given time....


You can ALWAYS predict where the impactor must impact with a given world... ALWAYS. You may not know where in its orbit, the world will be when the impactor hits, but the impactor's high speed works against the impactor as much as it works against the defense.

Why?

If the built up velocity of the impactor is higher than its acceleration can modify its course - the more precise its path must be to insure that it hits the target world at all. If for instance, it jinks for 2 minutes worth of time in one direction at say, 6G acceleration, but has achieved a velocity of .8 C's - the "jinking" displacement is a really SMALL percentage of volume that the impactor can move within, relative to the path it must take in order to hits a planet with a known velocity or a known location at a given time.

To put it another way? The closer the impactor approaches its target world, the smaller the cone of volume will be that the impactor must travel within - in order to hit the target world.

So - the faster the impactor's movement towards its target world, the more "narrow" the cone of possible movement on the impactor's part, from its last known location. The target's motion is predictable, and from that, the volume of space the impactor has to travel becomes reasonably predictable.

 

[Omnivore]

So - the faster the impactor's movement towards its target world, the more "narrow" the cone of possible movement on the impactor's part, from its last known location. The target's motion is predictable, and from that, the volume of space the impactor has to travel becomes reasonably predictable.

Reasonably predictable - your target is a freight truck somewhere in Kansas. Worse, your target is 1000 fragments of what used to be a freight truck somewhere in Kansas. Reasonably predictable isn't good enough.

The point where the trajectory narrows significantly is also the point where the vehicle will MIRV since it is far more effective to hit a thousand separate points than a single one.

Remember that the impactor can vary its trajectory in any direction, including the amplitude of its vector. In other words, you don't know where within a say 1/10 of planetary diameter it is aiming at and you don't know when it will impact exactly. On top of that, it's an extremely small target - the size of a small craft prior to MIRV and a thousand basketballs afterwards. Worse, even if you hit them - doesn't matter - the energy will still impact at that point.

PS: yeah I know I said last post earlier - but had to point out that its a problem in four dimensions not three.

 

[BytePro]

If near-c weapons didn't exist and one is not working within the limits of Traveller acceleration - sure. Otherwise - jumping in and ramping up is even less effective overall.

 

[travlar]

Well, it's always possible that densitometers don't have detection lag. As far as I know, anyway, no one has figured out what speed gravity travels yet. Or I could just be horribly wrong, and maybe they have. But if densitometers don't have that lag, it would help the accuracy a lot. Beyond that, there's still questions like when would the world detect it, and how long can the vessel survive near C travel.

 

[mike wightman]

Gravitational waves and gravitons - if either exist - propagate at the speed of light.

 

[Hal]

Reasonably predictable - your target is a freight truck somewhere in Kansas. Worse, your target is 1000 fragments of what used to be a freight truck somewhere in Kansas. Reasonably predictable isn't good enough.

The point where the trajectory narrows significantly is also the point where the vehicle will MIRV since it is far more effective to hit a thousand separate points than a single one.

Remember that the impactor can vary its trajectory in any direction, including the amplitude of its vector. In other words, you don't know where within a say 1/10 of planetary diameter it is aiming at and you don't know when it will impact exactly. On top of that, it's an extremely small target - the size of a small craft prior to MIRV and a thousand basketballs afterwards. Worse, even if you hit them - doesn't matter - the energy will still impact at that point.

PS: yeah I know I said last post earlier - but had to point out that its a problem in four dimensions not three.

We're pointing out both sides of the coin as far as 4 dimensions rather than 3. However, you've negelected the fact that the delta velocity issue of the impactor is within known aspects, plus - once a given value of velocity is achieved, that known "displacement" becomes smaller and smaller relative to ALL of the factors involved in trying to impact against a planet at a known point in time and space. A 6G acceleration impactor, can change its velocity (and thus displacement) by no more than 6 x 9.8 meters per second per second. Any variation OFF the true impact path required to hit its target - will also require it to move BACK onto the path in time to hit its target. This is why the targeting solution for both the impactor itself against the planet, and the planet's defenses against the impactor - narrow down into a cone function of possible locations that can STILL hit the planet (and thus narrow down where the impactor has to be in order to hit the planet).

In all? The closer the impactor gets to the planet, the more precise its aim has to be. If it is releasing basketball sized objects, these objects are ultimately SMALLER than a missile, and subject to repulsor bays and sand casters. Now, the real question becomes one of how much time the defenders have to detect the incoming impactor.

Also - the question becomes one of whether or not a ship can handle the high fractional C speeds and not suffer what amounts to battle damage with simple collisions with small objects. Sand particles count as small particle objects. Multiple sand caster particles thrown out by a huge ship designed specifically to counter high fractional C velocity impactors may be sufficient in and of themselves (maybe - because we're talking about a ficitional universe with a fictional technology). One thing that has always intrigued me was the creation of the sand caster technology. How does a swarm of sand stay sufficiently together to offer protection during 20 minute rounds of combat (or 1000 second rounds of combat in Book 2 rules). Then it crossed my mind that if there are artificial gravity generators, it wouldn't be a major stretch to include miniature gravity generators to help keep the sand from spreading. Is this the case? Probably not - but often times, game designers build the effect first, then worry about justifying it later.

In any event - hitting a planet with a high velocity impactor is NOT an easy task. Don't believe me? Try it out using vector math where the target is moving at a known velocity of 29.8 km per second, and then try to have an impactor of any given speed you care to try out as the basic moving speed, and then attempt to have the impactor "dodge" about. The 6G acceleration relative to the built up speed, is going to have so little impact on the "displacement" of the impactor relative to the target that it MUST strike with precision.

80% lightspeed means that the impactor is moving at a speed of 239833 km/s versus a world whose movement will be (to use Earth as an example) 29.8 km/s.

There isn't a LOT of leeway for the impactor to not be aimed precisely at where the planet will be at a given point in time - not when dealing with a drive whose max acceleration is roughly only .02% of the relative velocity of the impactor itself.

Absent the math proof, which I can not provide - we can't really determine the outcome of this hypothetical exercise.

The first issue is determining where the object is relative to the world it will strike against. That is a BIG issue. Having only say, 8 minutes to respond to such an event, will be bad enough as most reaction times for a naval vessel will not be able to respond to it. However, building up to fractional C velocities takes time, and that might be detectable - maybe. Aim at a planet from that far out as one attempts to make navigational fixes on the impactor versus the target it intends to hit - may also be something of a problem.

 

[Dragoner]

Even a small kinetic hit can nudge a impactor off target.

 

[BytePro]

Or 'just place' a bunch of 'big rocks' in the way - any 'ultimate weapon' can always come up against an 'ultimate defense' in imaginary worlds... (Ad infinitum).

Imaginary budgets and imaginary tech all provide for whatever one desires... IMTU, near-c impactors are a 'possibility' (i.e. I never house ruled velocity limits) - there are also technical reasons it is largely impractical, defenses to defeat it for those that have the means, ways those defenses can be defeated (including man in the field), and social/political repercussions that make it exceedingly rare. In practice, tiny fraction c impactors have informed the backstory and planetary defenses, with only one plot featuring such more directly (with players witnesses to a genocide... and identified fleeing the system :devil.

The rules support numerous options - and if they didn't, then I would just implement my own rules.

The Ultimate Weapons is simple Will. Sometimes it succeeds.

 

[Hyphen]

Well, it's always possible that densitometers don't have detection lag.

This is exactly the basis for FTL comms in Honor Harrington's universe.

 

[Omnivore]

I'm going to hate myself for continuing this discussion

Information lag - effect of light speed limited sensors and weapons.

At 75% c, at time t, distance to target of 10 light seconds, your sensor readings show where the target was 7.5 seconds ago. It will take somewhere around 2 seconds for your light speed weapon to reach any of the possible target locations. Let point x be the location the target would be if it performed no maneuvers between time t and t+9.5. Assume the target can maneuver each second such that it can change its straight line projected position by even as little as 5 times its cross section in any direction each second.

The possible locations for the target covers an area well over 6000 times its cross section at time t+9.5.

Yes, this becomes more constricted but the RKV's target is *not* a predictable point. For a size 8 world, it is any of 20000 points (if each point is considered to cover the RKV's cross section area). This means the target can continue to maneuver to any of the 6000+ positions possible at each step as long as the endpoint trajectory ends at one of the 20000 points.
The 3d graph looks something like a water filled condom, with the nipple being the RKV's last recorded position and the open end at top being the possible impact locations.

For weapons traveling slower than light speed such as N-PAWs and much much worse missiles or sandcasters the scenario is even less favorable to the defender. Sandcasters are pointless during the final 500000km or so - it does you no good whatsoever to turn the incoming mass into plasma. The majority of the RKV's energy is still going to be delivered to the planet.

Regardless of weapon employed, you are pretty much only going to have one shot per weapon. As cheap as the RKV's are, a staggered pattern of a dozen could pass through your weapon range before you could get a second shot off.

Which brings up yet another point, depending on what kind of detection ranges you assume, it is going to be rather difficult to get any weapons platforms into range in time to do any good. Orbital satellite defense platforms are utterly useless as they are less than 0.2 seconds from the planet. Even a direct hit by a multi megaton nuke wouldn't do much to alleviate damage at that point. If you are the defender, neither Einstein nor Newton are on your side.

All this assumes OTU Traveller or harder scifi basis of course. Magitech can solve anything.

 

[Carlobrand]

Wow. My ill-fated little scout/courier only managed about 0.01c. You guys are scary.

Here's an interesting twist to the thought exercise. I had a thought of hitting a sun and making a splash that way, but even if I ratchet it up, my little ship's impact is peanuts compared to the power of a solar flare on your typical G-2 V, and that's never been an earth-shaking event for the Solomani an AU distant. However, there are a lot smaller stars, and a lot closer worlds - Porozlo, for instance. What would happen if you plunked one of those C-monsters into, say, an M1-V with a world orbiting at Orbit-0, 2/10ths of an AU from its parent star?

 

[Hal]

I'm going to hate myself for continuing this discussion


All this assumes OTU Traveller or harder scifi basis of course. Magitech can solve anything.

Doing the admittedly *SIMPLIFIED* Math:

Velocity = A x T, where Accelleration = 6 G (max accel for CT ships) or 58.8 meters per second.

Displacement = 1/2 Acceleration x time x time

It would take approximately 4078808.952 seconds to attain a velocity of 80% light speed.

Displacement however, would be roughly equal to:

((9.8 x 6)/2) * 4078808.952^2

The answer above would be the distance travelled in meters. Divide that whole value by 1,000 to get an answer in kilometers.

The answer I got? 489,118,464,619 km

So, I was curious. How far is that overall? In AU's, this works out to roughly 3269.55 AU's in distance. In light years, this is about 5% of a light year.


So - the aiming mechanism for this weapon system, has to be Exceedingly accurate to hit a target that is roughly 3269 times the distance that Earth is from the Sun, and be able to accelerate sufficiently well enough to correct its course sufficiently to slam into a world that it will take roughly 47 days to strike?

If an instrument is off by a mere 1 second of one degree (1/3600th) - how accurately could it strike a target with a light speed velocity (ie a laser beam) and still its target that is 3,260 au's away? It is simple trig where you know the angles of all three apexes of a triangle (90 degrees, 89.99972222222 (repeating) and 1/3600 as the final angle. Determine the lengths of the three sides of said triangle, where the one side (opposite the Hypotenuse) is 489,118,464,619 km. The other two sides can be determined using the sine rules etc.

Wanna bet that the faster you go, the harder it will be to make course corrections where the distance of "error" (ie the distance in which your one second of one degree accuracy) can STILL miss an Earth Sized planet?

Play with the math and see what answers you get.

 

[Omnivore]

I cheat on the math: http://www.cthreepo.com/lab/math1.shtml.

As for the deviation, that's why it has an onboard computer and nav system along with at least rudimentary sensors. The trajectory (including evasions) would be preplotted by the launching vessel, but the RKV would be responsible for mid course corrections.

Considering the distances involved with plotting jumps, I don't believe a military vessel's computer would have much of a problem determining a decent enough initial trajectory.

Now, all that said, you have hit upon a possible defense if you abandon Traveller's detection rules and do not allow for stealth (particularly in the IR band) in deep space. Even better if you disallow gravitic drives to achieve relativistic speeds. Depending upon design and terminal velocity desired, the RKV is going to be accelerating for somewhere between 3 and 6 months beginning at a point somewhere between (for Sol system) the Kuiper Belt and the Oort cloud in distance and ideally at an angle far removed from the ecliptic plane.

Given sufficient sensor coverage of the outer system, you might get lucky enough to spot flights of RKVs early in their voyage and have sufficient time to jump warcraft into intercept positions before they reach a significant fraction of light speed. It would still likely be a long shot proposition but would be a much better defense than you'd face later on.

PS: Carlobrand - I have not a clue on what it'd take to reliably trigger a solar flare out to even 0.2AU distance from a M1-V star. My gut instinct is you'd be better off launching the RKVs at the world itself.

 

[Hal]

I cheat on the math: http://www.cthreepo.com/lab/math1.shtml.

Here's a quickie web site that will do the trig calculations for you.

http://www.csgnetwork.com/righttricalc.html

When I get the chance, I'll spend more time figuring out how far away from Earth the Impactor/Ship has to be in order to miss by only the diameter of the Earth itself (I think the distance is roughly 18 AU's with a sensor that is accurate up to 1/3600th of a degree - which I'm using to illustrate just how god awful the sensors have to be and the pilot has to be in aiming his ship directly at a target. Even the Laser turrets in the Traveller universe are unable to accurately hit a target at a major distance of only 3 light seconds with any level of certainty.

But, let's look at the numbers when we get the chance.