The ultimate weapon

[drkem99]

A few thoughts. First, the fact that STL interstellar travel is possible by canon (the Islands subsectors in Reft Sector were settled that way, and canon has many other references to STL travel) implies that the issues with interstellar dust impacts with the hull at relativistic velocities must have an effective technological solution. Otherwise, the colonists would all have died en route. Pick one you like.

Second, STL interstellar travel does not mean that reactionless thrusters must be involved. There are other possible solutions; I personally like antimatter-catalyzed fusion drives using Bussard ramjets for hydrogen fuel as the drives for the colony ships. (See here and here for design details; the longer flights need the Bussard ramjet technology to meet fuel requirements.) The resources required to produce the required mass of antimatter fuel (and launch lasers, if you also use that technology) require a massive commitment of planetary GDP and time (probably decades-long) by the launching star system. This ensures that STL ships are not commonplace but will allow their use in canon. The GM may still use reactionless thrusters if desired with a 'speed limit' using whatever technobabble explanation suits your campaign in order to avoid relativistic weapons.

Third, I have to agree with Omnivore on the problems system defense will have with relativistic impactors. I would say that the existence of piracy in the OTU argues against massive sensor networks covering a system in excruciating detail in all but the most heavily settled star systems. (And how about all those high population, low tech worlds?) I also believe that synthetic aperture radar and long baseline arrays trade time and image quality respectively for spatial resolution; both tradeoffs will limit the effectiveness of the sensors for targeting. Precise shorter-range targeting sensors will run into the critical issue that Omnivore has described well (the small gap between the signal detected and the arrival of the near-C object.) Consider that Traveller point defense systems are a long way from 100% effective against standard starship missiles and fighters moving at a glacial pace compared to our relativistic impactors; I'm not sure with the sensor issue the defense will perform better against our hypothetical planet killers.

Finally, Niven pointed out in his Man-Kzin War stories that if you only attack planets with a relativistic weapon, you aren't thinking big enough. Large starship-sized relativistic weapons can destabilize stars. (Who needs the Star Trigger?)

As I commented recently in my blog, I think a GM needs to admit that the basic Traveller canon without further interpretation could permit a relativistic impactor, and the GM should decide in his own mind why they do not exist in his campaign world. Otherwise, there will be SLAGGED planets everywhere...

Nice to see the return of a classic green-purple argument to the forum.

 

[Gray Pennell]

Except for STL colony ships the easiest answer as to why you dont have impactors is engines may exploded at 6g+ or for going too long at 6g. Its just a matter of material strength. It doesn't violate the laws of physics probably compliments them.

Now for STL colony ships those buggers put a cramp in my argument and I guess we cam just say being fueled by exotic materials they are too costly, inefficient and dangerous to be used by the races of CT or latter TUs.

 

[aramis]

A few thoughts. First, the fact that STL interstellar travel is possible by canon (the Islands subsectors in Reft Sector were settled that way, and canon has many other references to STL travel) implies that the issues with interstellar dust impacts with the hull at relativistic velocities must have an effective technological solution. Otherwise, the colonists would all have died en route. Pick one you like.

Actually, canon has the answer... in CT Beltstrike, Folder 1, p. 2:

(Ships under power are not affected - part of the M-drive generates a low-power screen against radiation and meteorite impact- but a power failure during approach within a few million kilometers of the gas giant would be fatal.)​

 

[drkem99]

Aramis is (as usual; why am I not surprised?) correct; it's a good, canon-based solution. While it does have a touch of handwavium to it, solving two problems with one bit of handwavium has an economy to it I appreciate.

Too bad coherent superdense wasn't introduced earlier; you could just increase the power supplied to the hull to reinforce the atomic bonds when the radiation or the micrometeorites get bad. We could copy Enterprise and call it 'polarizing the hull plating'.

 

[jshiggin]

Except for STL colony ships the easiest answer as to why you dont have impactors is engines may exploded at 6g+ or for going too long at 6g. Its just a matter of material strength. It doesn't violate the laws of physics probably compliments them.

Now for STL colony ships those buggers put a cramp in my argument and I guess we cam just say being fueled by exotic materials they are too costly, inefficient and dangerous to be used by the races of CT or latter TUs.

You don't need to accelerate at 6G+ to get to relativistic speeds. 1G will work nicely, as long as you're willing to deal with taking 6 times as long.
Start from a parsec out, accelerate at 1G continuously, and you're moving at 97.3% of lightspeed.
Requires that your ship/missile have fuel for 26 months of acceleration, though it takes just over 50 months as the target measures time. Relativity - gotta love it.

Note that in MT rules, no "normal" ship could actually do this - too much H2 required. But it would be possible to design a purpose-built weapon that could accomplish the mission. Maybe...

Under HG rules, it would be pretty trivial - any J4 ship would be capable of doing it without even carrying extra fuel tankage in the hold.

 

[DangerousThing]

As I commented recently in my blog, I think a GM needs to admit that the basic Traveller canon without further interpretation could permit a relativistic impactor, and the GM should decide in his own mind why they do not exist in his campaign world. Otherwise, there will be SLAGGED planets everywhere...

Nice to see the return of a classic green-purple argument to the forum.

Unfortunately I agree that such an attack is possible.

What about active defenses such as some sort of deflector shield? Perhaps based on repulsor technology? Some sort of shield that would surround a *large* area such as a planet or sun and toss away anything that was going above some stated velocity X.

As long as we're hand waving, I'm thinking of some sort of aikido-like shield where the attacker's momentum would be used against him.

This might now work in the 3I but it might work in my ATU where the core systems are 14-15. The rim worlds (systems recently taken into the Empire) might have a problem, but they are less likely targets.
-
Jay

 

[BytePro]

For ships, I've used a 'C-Vector' shield that deflected high velocity objects. It had a huge power drain.

For a cool concept in planetary defense I highly recommend Adiamante by L. E. Modesitt Jr.

 

[rancke]

Unfortunately I agree that such an attack is possible.

So it is without further interpretation.

What about active defenses such as some sort of deflector shield? Perhaps based on repulsor technology? Some sort of shield that would surround a *large* area such as a planet or sun and toss away anything that was going above some stated velocity X.

As long as we're hand waving, I'm thinking of some sort of aikido-like shield where the attacker's momentum would be used against him.

If you're OK with adding something as monumental as deflector shields, what's wrong with instead adding an upper limit to the energy a thruster drive can add to a ship? For example, that it reaches its limit after one week of steady acceleration?

(I'm not quite sure how much explosive force that would allow; perhaps it would also be too much. But one week is the maximum you need to accept that the rules allow; if a trip would take longer, you'd jump instead. (Long range colony missions would have used other propulsion systems, such as ramscoops.)


Hans

 

[McPerth]

What about active defenses such as some sort of deflector shield? Perhaps based on repulsor technology?

I'm not sure repulsors would potent enough for that. If you are approaching to a meteorite (to put an example) at speed (relative) 0.3 G and you must deflect it from 25000 km (a square in MT, though I guess the repulsors range is quite less), you have only about 0.08 seconds to deflect it, so, how many Gs will you need for that?

Repulsors are thought to deflect missiles at quite slower relative speeds, so I don't believe they can apply the needed force to deflect them in time.

Same applies to any shield, IMHO, more so as they will probably have even less range, and 'hitting' a meteorite with your shield will make it to explode and release too much energy for your 'ship' to be left unharmed.

 

[Blue Ghost]

Getting back to the OP, I think it's a non-issue. Any defensive measure will have taken this into account. Just as we track all of the NEO objects today, so would likely be with outer perimeter defenses.

Just thinking about it, for worlds in border sectors there'd probably be a layered defensive structure, possibly starting at the Oort cloud, then gradually intensifying the closer you got inward. Tossing interceptors in the thing's path would more than work, and detection would be a breeze. Tracking would be another matter, but in order for the attacker to maintain their energy they would have to expend energy for evasive. That, and IIRC my CT jump rules correctly, a ship doesn't constantly accelerate when travelling through space.

Turning the thing into a hunk of plasma would be plenty effective. That plasma would dissipate quicky; i.e. expand to non-cohesion in addition to being pushed apart by "solar wind", the energy we're protected from here on Earth. Plasma only exists under certain conditions, and like all energy, that state needs fuel. Destroying the scout ship would create plasma side effects, but that cloud would last fractions of seconds at best.

The tactic first presented wouldn't be "diabolical beyond belief" and create a deterrent. It would merely be impractical.

 

[aramis]

Getting back to the OP, I think it's a non-issue. Any defensive measure will have taken this into account. Just as we track all of the NEO objects today, so would likely be with outer perimeter defenses.

Sadly, we can't even track all of them. We track most of them that we know about... some as low as a few mm...

And coorbital or semi-coorbital bodies (like the "horseshoe orbits") are still being discovered. Plus a new earth crosser or two a year seems the norm for comets.

 

[Blue Ghost]

Sadly, we can't even track all of them. We track most of them that we know about... some as low as a few mm...

And coorbital or semi-coorbital bodies (like the "horseshoe orbits") are still being discovered. Plus a new earth crosser or two a year seems the norm for comets.

Granted, but something that's really hauling across space would certainly be detected. It's cross section or other signature might not be easily detected, but it's trail and vector would raise an eyebrow here and there.

 

[77topaz]

Granted, but something that's really hauling across space would certainly be detected. It's cross section or other signature might not be easily detected, but it's trail and vector would raise an eyebrow here and there.

If it moves too fast, it won't be detected until it is already too late... :devil:

 

[Blue Ghost]

If it moves too fast, it won't be detected until it is already too late... :devil:

No, that's not really correct. If it starts out on the outer edge of the system, then there's plenty of time to get a rough course estimate as to where it's going. Even if it starts in close, it needs to accelerate according to rules. The acceleration alone would be detected, giving ample warning.

I think it's a non-issue. I think the only time that it would be a credible threat would be something like a terrorist attack on an inner system that didn't have a robust defensive network nor navy that was constantly on patrol.

 

[Omnivore]

No, that's not really correct. If it starts out on the outer edge of the system, then there's plenty of time to get a rough course estimate as to where it's going.

Eh problem is 1) detecting and 2) intercepting - both of which are complicated by the sheer distances involved as well as by light speed limits, relativistic effects, and week long micro jump ftl. Its even worse if enough of the vector is preserved across jump so that the vehicle starts off at 15% light speed or higher.

But, as I noticed a few pages back, this is a purple green debate. Pretty much impossible to convince anyone to switch from one side to the other as the answers are in the assumptions you come to the subject with and the type of universe you want to portray.

 

[BytePro]

The rules also allow Jumping in at high speeds...

 

[Whipsnade]

The rules also allow Jumping in at high speeds...

Yes, but given jump's temporal and physical accuracy, "aiming" through jump space is all but impossible.

[I wrote "all but" because someone will come up with a Golden Moment example in which several dozen factors all come together perfectly in order for a near-c object to be "aimed" through jump. ]

The near-c rock problem in Traveller has been discussed for longer than some of our members have been alive and with as little resolution as has been seen in this thread. As another poster already and wisely suggested, it's up to each indiviudal GM to come up with the explanation which works in their Traveller Universe be it MAD, m-drive shileding breaking down past certian velocities, m-drvies not working past certain velocities, etc., etc., etc.

This topic - like the question of why lasers in the setting aren't used to blind people because that is easier to do - is essentially a barren one. You'll get nothing for your effort.

 

[BytePro]

...
This topic - like the question of why lasers in the setting aren't used to blind people because that is easier to do - is essentially a barren one. You'll get nothing for your effort.

In the nature of a rules based or OTU solution - that is quite true.

It does have merit in terms of discussing possibilities...

 

[aramis]

Granted, but something that's really hauling across space would certainly be detected. It's cross section or other signature might not be easily detected, but it's trail and vector would raise an eyebrow here and there.

A lot depends on if it's moving across the field of view or not, and if it's moving across fast enough to not be realized that it's the same object that far apart.

 

[Blue Ghost]

A lot depends on if it's moving across the field of view or not, and if it's moving across fast enough to not be realized that it's the same object that far apart.

I question whether the aspect makes all that much difference. The return at event 1 is different form the return at event 2. If you pick up an object at X1, then pick up a similar return at X2, but with a different size and distance measure, though still in the same frame reference on the screen, then it seems reasonable that said object, if it is the same object, is approaching you. Delta-X over Delta-T tells you the velocity, and you can discern the X-Y-Z (i.e. vector) from the returns. At C, it takes what, six minutes to get a particle/wave from Earth to Jupiter? .15C, might give you enough lag to get an extremely fast countermeasure in place.

I don't know, I've uninstalled MathCAD and Maple from my computer ages ago, and I can't recall the calc-version of physics' formulas off the top of my head, but it seems like in order for an object to get to fifteen percent of the speed of light, that it would need to accelerate appreciably after jump. And to me, it seems like that kind of tactic is subject to detection.

I do agree, however, that if somehow said ship was already hurling at a fraction of C as it exited Jump, then said tactic has a good chance of succeeding. But, like others have pointed out, your Ref and mileage may vary.

It's an interesting proposition, but I think its feasibility is more in the realm of "how much do you think it's cool for your players to face this challenge" than a hard story element for the sake of it.

I need to get back to painting.