A little doomsday weapon, perhaps ?

[rinku]

Debris defence may have its work cut out for itself. The suicide ship has as much time to maneuver as it wants (one of the reasons I used a normal M-Drive rather than rockets), so you can't be totally sure of its vector. It doesn't *have* to accelerate all the while - that was just the simple case. The debris cloud is going to have to be quite dense and widespread to have any chance of an impact. I seriously doubt any normal sandcaster has the ability to do so with any realistic chance of a hit, though something mounted on a missile might have a shot.

Missiles may work, but are hampered by a lack of endurance. They won't be able to match velocities, so have to go for a frontal collision kill. Against a maneuvering target, that's going to be tough, and they only get one shot.

At several hundred km per second, you'll only have one space combat turn in which to engage it normally, with whatever systems you are using.

It's a tough proposition. Oh, and did I mention I'd expect these to be used in swarms? Even a few hundred of them will be far cheaper to produce than a single major battleship. Or you could make 100 Dton ones that strike with a "mere" 15 Megaton impact...

Re smuggling in a nuke... you're probably right, though a special forces team dropping onto a planet probably requires more in money and risk terms for their stealth ship, special forces training and extraction (unless they are also on a suicide mission, in which case their training and equipment is not recovered).

 

[Mongoose Pete]

Debris defence may have its work cut out for itself. The suicide ship has as much time to maneuver as it wants (one of the reasons I used a normal M-Drive rather than rockets), so you can't be totally sure of its vector. It doesn't *have* to accelerate all the while - that was just the simple case. The debris cloud is going to have to be quite dense and widespread to have any chance of an impact. I seriously doubt any normal sandcaster has the ability to do so with any realistic chance of a hit, though something mounted on a missile might have a shot.

The sandcaster carrying vessel simply needs a 6g manoeuvre too. Its only the lateral vector it needs to match, mirroring whatever the approaching target is doing (cancelling the accel/decel aspect with a head on approach vector). Also the probable surface based targets of the suicide ship should be easy to predict, so the defending vessel will technically need to only cover a small arc to guarantee an interception, a bit like a goalie coming out from the goal to cut down the angles.

Missiles may work, but are hampered by a lack of endurance. They won't be able to match velocities, so have to go for a frontal collision kill. Against a maneuvering target, that's going to be tough, and they only get one shot.

Actually for my plan to work, only a frontal collision would work anyway, since its relying on the velocity of the ship to provide the destructive energy.

At several hundred km per second, you'll only have one space combat turn in which to engage it normally, with whatever systems you are using.

Very true. But you could always stagger a line of low orbit interceptors to get several chances. Or have the city (or whatever the target is) itself launching the ordnance to strike at the top of the stratosphere - tracking hypervelocity railguns on rapid-fire perhaps?

However, for both missiles and sandcasters the difficulty of hitting only comes from predicting the lateral dodging. So in games terms it is no more difficult than point defence hitting an incoming missile for example (or any other dodging ship at Traveller space combat ranges). In fact, since it has to approach down a steadily narrowing cone, the chance of interception should actually improve.

It's a tough proposition. Oh, and did I mention I'd expect these to be used in swarms? Even a few hundred of them will be far cheaper to produce than a single major battleship. Or you could make 100 Dton ones that strike with a "mere" 15 Megaton impact...

Eek! It might be cheaper than a battleship, however, its still a scary amount of money to throw away on a single attack.

Re smuggling in a nuke... you're probably right, though a special forces team dropping onto a planet probably requires more in money and risk terms for their stealth ship, special forces training and extraction (unless they are also on a suicide mission, in which case their training and equipment is not recovered).

The hull of your streamlined 1000dTon ship is 110MCr, plus 88MCr for the 6g M-Drive, plus 176MCr for the power plant and 60MCr per level of Meson Screen (3 max). Without armour and internal components you're looking at a base cost of a little over half a billion. :shock:

12 small nukes cost 45,000, so a big nuke might be around 50KCr. The special forces team could land with any old ship as long as it had a legitimate reason to visit the world. (I am of course assuming that unless the target planet was technologically challenged or massively inferior, no stealth ship can land without detection.) You could always smuggle in parts of the bomb piecemeal and construct in-situ, which as long as you are not using fissiles as a trigger, or the world has a draconian law level, should be relatively easy.

Well, I think that's the way a military command will look at it. Men are cheap, ships are not, and half a billion is a very expensive route to what is effectively a very modest bang. (I'm not sure a smiley is appropriate considering the subject matter, but the conceptual exercise is fun!)

 

[rust]

The hull of your streamlined 1000dTon ship is 110MCr, plus 88MCr for the 6g M-Drive, plus 176MCr for the power plant 60MCr per level of Meson Screen (3 max). Without armour and internal components you're looking at a base cost of a little over half a billion. :shock:

This is the price tag of almost 30,000 nuclear warhead torpedoes, and in
my view these would be a far more frightening attack, because they would
almost certainly overload the planetary defence system, and if only 1 %
or 300 of them would explode in the atmosphere or on the ground, the de-
struction would most probably damage a far wider combined area than a
single mega-hit could do.

So, if someone in my setting really wanted to make a planet uninhabita-
ble, he would almost certainly develop torpedo pods with several dozen
torpedoes each, with all of the torpedoes from all the deployed pods laun-
ched as one overpowering salvo, and then count on the nuclear winter ef-
fect caused by the multitude of nuclear explosions to do the rest.

 

[BP]

In 1961, the Ivan (Tsar or King of bombs...) was air detonated - it had a designed yield of 100 megatons, but was intentionally restricted to 50 - IIRC, the U.S. claims it exceeded that...

So, a more effective method might be to Jump in several ships at very high velocity already (otherwise, at 50D in the above example, active defenses are gonna have a very good chance of neutralizing the kamikaze ships) and launch missiles from them.

As a known threat, defenses would be designed to address this, however, given enough Jump re-entry velocity, the only truly effective method of deterrent might resolve to Mutually Assured Destruction.

['Brainstorming' here... some game mechanics that might work against this form of attack being viable could include inaccuracy of Jump at high 'velocities' (relative to whatever?); 100D limit greatly expanded at high velocities (now this might work given relative nature to target mass); or, the inability to travel at high velocities without risks of destruction from interstellar objects.]

 

[DFW]

If this were a recognized threat I could see a gov't having some Ni-Ir asteroids in high orbit with M-Drives that are remotely controlled. Simply maneuver one or more into the path.

 

[BP]

The path of the attacker, or the path of the target... :lol:

 

[DFW]

The path of the attacker, or the path of the target... :lol:

Both. (Catcher - Bat - Ball)

 

[BP]

Nah, that wouldn't work as a practical defense... :roll:

But the title to this thread, little doomsday weapon, perhaps?, has planted the seed for my next campaign :twisted: - Thanks rust!

 

[Mongoose Pete]

['Brainstorming' here... some game mechanics that might work against this form of attack being viable could include inaccuracy of Jump at high 'velocities' (relative to whatever?); 100D limit greatly expanded at high velocities (now this might work given relative nature to target mass); or, the inability to travel at high velocities without risks of destruction from interstellar objects.]

Some possible answers...

1) Accelerating up to velocities beyond several thousand km/s will probably be very difficult unless you can find an exceptionally clean region of space. Granted that you can however, jumping into an inhabited system will place you back into a densely populated sand/grit/paint fleck region - most likely taking care of the situation without any need for action by the defenders.

2) Conversely, assuming the ship can withstand the sand blasting, emerging at the 100d limit will give a 6g ship travelling at 2000km/s a mere 500 seconds before crossing a million kilometres. Assuming no forwards velocity change it could offset its vector by up to 7500km before running out of time. Since however the planet itself is moving, about 30km/s in the case of Earth, the planet will move such a distance itself in 250 seconds.

In the case of a high speed attack, this means (assuming my math is correct) the initial jump will have to be incredibly accurate in order to actually intersect the planet before the world moves out of its trajectory cone. Since as I pointed out earlier, jumps can vary by 6d6 hours - the chance of the vessel being able to hit the planet becomes increasingly tiny the faster its travelling at exit.

3) Extrapolating from DFW's comment, I could see important or paranoid worlds seeding/mining low orbit with a band/shroud of 1g steel ball-bearings. A density of 1 per m3 with a depth of 10m should give fair odds of a collision. Population/infrastructure dispersal on the surface will govern how extensive the bands need to be. All vessels wishing to land on the world below would need to maintain (relatively low) safe speeds in order to push through the cloud without harm. No problem for surface to orbit shuttles.

This assumes gravitics to achieve orbit and the sacrifice of a few dozen (or more) cubic kilometres of metallic asteroids of course, with the occasional top up for good measure... :wink:

 

[BP]

Under the impression in the OTU, that 6d6 hours simply is a change in when it emerges, not necessarily where? (Though, IMTU, the where and the direction of re-entry are also randomized )

Creating a high deltaV 'shield' for a planet sized object, significantly separated enough from the planet to provide adequate protection, using even small mass balls, would require huge masses of materials, which would also need to be accelerated to orbital velocities and maintained - though the image of ships having to slow to safe entry speeds while being pelted by pinging metal balls is appealing 8).

(P.S. - a good idea for intra-system 'speed bumps' ala your prior speed limit scenarios, at least for established 'space lanes'.)

Of course, at high velocity, the impactor (er ship) - which doesn't need to worry about maneuvering in defense, BTW - has little to fear from small particles that are more likely to go thru the vessel, than obliterate it or change the course/dispersion of most of its mass.

But, as with any offensive/defensive tech - countermeasures would ensue. In the case above, a 'simple' dispersion mechanism (pre-shield, explosion, gravitic device, etc) would likely be used...

 

[DFW]

Nah, that wouldn't work as a practical defense... :roll:

That's true, smacking into a solid iron asteroid wouldn't stop the ship. :roll:

 

[DFW]

2) Conversely, assuming the ship can withstand the sand blasting, emerging at the 100d limit will give a 6g ship travelling at 2000km/s a mere 500 seconds before crossing a million kilometres. Assuming no forwards velocity change it could offset its vector by up to 7500km before running out of time. Since however the planet itself is moving, about 30km/s in the case of Earth, the planet will move such a distance itself in 250 seconds.

Quite correct. With this in mind there is another major fly in the ointment. So far this has been planned on the premise that you will exit jump space at an exact time so as to be lined up with the planet. In MGT this isn't the case.
You will probably be early or late and therefore the planet will not be in the expected position...

 

[BP]

Nah, that wouldn't work as a practical defense... :roll:

That's true, smacking into a solid iron asteroid wouldn't stop the ship. :roll:

Correct - simple physics 101 - the asteroid is not going to stop! :lol:

As a practical defense, simple math defeats the idea - the asteroids have a specific velocity to be in orbit (or massive fuel requirements to maintain higher velocity yet still be in place for defense) - which precludes them being able to get in position in time, or requires too many bodies to be practical (especially if one wants to support inbound space traffic).

 

[Mongoose Pete]

Of course, at high velocity, the impactor (er ship) - which doesn't need to worry about maneuvering in defense, BTW - has little to fear from small particles that are more likely to go thru the vessel, than obliterate it or change the course/dispersion of most of its mass.

My premise must be wrong. :? I was imagining that if it had something like superdense armour, the impact energy would at the very least crack/warp the airframe, if not blast a reasonably sized hole. Once streamlining is compromised wouldn't the 100km (or more depending on impact angle) of atmosphere would finish the job?

Hmm. Just plugged the numbers into the Earth Impact Effects program, for an approximately 10 million Kg solid iron asteroid travelling at 2000 Km/s hitting the earth at a perpendicular angle (best possible outcome). The result was a 4920 Megaton airburst at 15.8 km altitude. Ouch!

Not much damage in actual impact debris, but the overpressure wave will flatten a fair amount of TL7 architecture! In fact it probably causes more damage by not reaching the surface. :shock:

Considering this was a solid lump of metal, I wouldn't be surprised if a ship simply crumpled and broke up from the incredible deceleration, probably at a higher altitude. Anyone here with an engineering degree and willing to crunch some ballpark numbers?

 

[Mongoose Pete]

Quite correct. With this in mind there is another major fly in the ointment. So far this has been planned on the premise that you will exit jump space at an exact time so as to be lined up with the planet. In MGT this isn't the case. You will probably be early or late and therefore the planet will not be in the expected position...

Which was the point I was trying to make, but I wasn't clear enough. :wink:

 

[BP]

My premise must be wrong. :? I was imagining that if it had something like superdense armour, the impact energy would at the very least crack/warp the airframe, if not blast a reasonably sized hole. Once streamlining is compromised wouldn't the 100km (or more depending on impact angle) of atmosphere would finish the job?

Depends on the rigidity (and area of course, but you were postulating small objects) - but in the case of 2000 km/s...

Hmm. Just plugged the numbers into the Earth Impact Effects program, for an approximately 10 million Kg solid iron asteroid travelling at 2000 Km/s hitting the earth at a perpendicular angle (best possible outcome). The result was a 4920 Megaton airburst at 15.8 km altitude. Ouch!

Curious which program did you use? (link please? )

That would be roughly 10~11 m on a side cube of iron? Atmo is compressible, so yes, very powerfull shockwave, though I doubt that program was designed to calculate what happened to the 10 million kg of 'shrapnel' - most would be 'vaporized', but plasma still goes somewhere - and your trajectory was 'straight' down for a mere fraction of a second (well in excess of any normal visitor from space that such simulations are designed for)

Not much damage in actual impact debris, but the overpressure wave will flatten a fair amount of TL7 architecture! In fact it probably causes more damage by not reaching the surface. :shock:

To life and tech - generally yes! (Same holds true for nuclear weapons.)

Considering this was a solid lump of metal, I wouldn't be surprised if a ship simply crumpled and broke up from the incredible deceleration, probably at a higher altitude..,

Yep - the ship would be 'toast' - but again, the force and matter has to go somewhere (even at that 'speed' all that matter won't be changing directly to energy)

All that said, as a WWD (Weapon of World Destruction) - Traveller ships, aren't really viable to me... sure ramming is a tried and true method of attack (that also has counter-measures), but tech offers more practical approaches... still, it would be a 'dramatic' roleplay option that has merit in that aspect.

 

[BP]

Quite correct. With this in mind there is another major fly in the ointment. So far this has been planned on the premise that you will exit jump space at an exact time so as to be lined up with the planet. In MGT this isn't the case. You will probably be early or late and therefore the planet will not be in the expected position...

Which was the point I was trying to make, but I wasn't clear enough. :wink:

Your point seemed clear (though DFWs was concise), though Jump space is not consistent with travel in normal space so the time difference wouldn't seem to directly relate to actual position. Those rules, of course, could be interpreted in different ways...

 

[Mongoose Pete]

Curious which program did you use? (link please? )

Here you go Death from above

Its still technically a rough model, but it is far, far better than anything else I've found and I'd never be able to wade through the equations by hand. Take a look at the pdf link at the bottom of the page. It makes some very interesting bedtime reading.

That would be roughly 10~11 m on a side cube of iron? Atmo is compressible, so yes, very powerfull shockwave, though I doubt that program was designed to calculate what happened to the 10 million kg of 'shrapnel' - most would be 'vaporized', but plasma still goes somewhere - and your trajectory was 'straight' down for a mere fraction of a second (well in excess of any normal visitor from space that such simulations are designed for)

I used a 13.5m diameter as the program assumes a spherical projectile. I also deliberately used a perpendicular impact angle to see what the greatest atmospheric penetration could potentially be. Shrapnel? I think folks standing within 20km would be more worried about spontaneously combusting in the heat flash...

I guessed that the program model would probably break down at excessive velocities, but it was interesting to see what it came up with.

All that said, as a WWD (Weapon of World Destruction) - Traveller ships, aren't really viable to me... sure ramming is a tried and true method of attack (that also has counter-measures), but tech offers more practical approaches... still, it would be a 'dramatic' roleplay option that has merit in that aspect.

I quite agree, on all points!

 

[phavoc]

If you needed a clean part of space, I'd suggest boosting your rock out of the plane of the ecliptic of the system, then coming in at your target from above or below the system plane. It's probably going to be the cleanest space you are going to find. Should be a relatively easy enough task to figure out where your target is going to be.

Plus above/below is probably going to be the least scanned portion of space, at least system wise. I'm sure there would be some scans, but not many.

 

[BP]

Curious which program did you use? (link please? )

Here you go Death from above

Thanks! (Seen it before, but those bookmarks are archived - one of the space agencies had one I really liked...)

A quick glance at the PDF - the time dependencies in the Thermal Radiation equations and the assumptions based on empirical models for breakup, I suspect, break down in relation to the 2000 km/s example... but, to be sure, the results are still impressive. (Actually, I suspect a more accurate model might be less dramatic re impacting the Earth - but that is a very relative statement!)

... Shrapnel?

'Shrapnel' - with the quotes!

Poor word choice, but at 2000 km impact to atmo, suspect one is left with basically balls of plasma with very high speed trajectories - some heading one's way. Not that it would matter much - but they may outrace the pressure wave...