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Limiting size of Jump capable ships
- Thread starter sideranautae
- Start date
Yes, I see your point. I am thinking this would be difficult to calculate.
Imagine a pillar of metal at rest and you shoot a laser at it. You keep firing until it melts and then boils. Due to increased pressure (a gas would expand relative to the more compressed solid/liquid states) it expands. But by how much. It isn't an explosion, just the effect of steam rising. So what is this? 10 cm / second? 1 meter per second? New steam keeps being created and fans out at 1 m/s creating a big cloud. Applying slight pressure on the missile so it changes course a very small amount the other way (a bit of gas pushing against a big solid piece). But this is cumulative so let's say that eventually everything is gaseous spreading out to the side at 1 m/s.
We would add the two vectors. One has the gas travelling on its original course at 5 million meters per second. The other has the gas move sideways 1 meter per second. If it is aimed at a very precise target in orbit this small variation in course could make a difference. But if it is aimed at the center of where the planet will be when the courses intersect, you need a lot of course correction. Earth has a radius of around 6,370 km. Okay, this is a size 8 world and a lot of worlds are smaller but would still want to miss the atmosphere too. Let's say that a 4,000 km course correction is sufficient. To get this correction (a 4 million meter correction) you would need to have boiled off the missile outside of 20 billion km.
Maybe the laser being fired is extremely intense. Kind of a spinal mount weapon, not just a standard starship weapon. Something so powerful it can push starships by firing at them. Something so intense that it turns a chunk of solid metal into a rocket with 2G of thrust over the time you fired at it. If it can boil off hull armor at that speed this would be one scary starship combat weapon (outperforming all spinal mount particle accelerators). But let's say such a super laser is used and you can fire at the target continuously for 1 minute. Such a laser would allow you to intercept the kinetic torpedo up to 2.8 million kilometers out.
If you can build and operate such a laser you still have to hit that moving target for that minute. Leaving aside targeting considerations (hitting a 3 cubic meter target travelling at extreme speeds that has zero emissions), you have to keep it in range for that full minute. What is the range of the laser? Regular starship based weapons (spinal mounts included) seem to cap out at 50,000 km. Can we multiply that by 10, to have a weapon that can fire 500,000 km? (would have an impact on overall tactics if you have defensive weapons that outperform weapons on attacking starships like that, but let's assume we can).
Cool. This 500,000 km range means you can be off to the side a little and fire as the kinetic torpedo passes by because it will take about 200 seconds to cross weapon range (less if the laser platform is moving - which it must have the capability of doing so because it would have to move out to around 1-2 million km out from the planet in a position to defend against the attack).
A less powerful or shorter range laser could be used much farther out (with more space to cover harder to be in position) or (even harder) matching vectors with the missile (starting out near the attacking ships - but way out of weapons range - and accelerating with them so you can be on a similar vector to the torpedo so you have lots of time to just keep firing at it).
Less dependent on having ships in lucky positions, I'm thinking that a wing of heavy fighters (maybe 50-60 tons each) with great sensors and communications equipment (to coordinate with larger vessels that have better sensors) firing tactical nuclear missiles at incoming objects. Such craft can be scrambled and (if your Traveller universe allows) be set up as drones with greater than 6G acceleration. Not useful against enemy capital ships that will most certainly have nuclear dampers but a dead weight kinetic weapon would have no nuclear damper protection. Each fighter can carry multiple (many) missiles such that you can do an overkill spread. (if you fire ten nukes at each kinetic weapon are you guaranteed at least one will hit?) Fighter craft that can be scrambled out when you detect ship(s) accelerating in at an unusual vector (one that doesn't allow turnaround and deceleration to reach planetary orbit). They don't actually launch the nukes unless there are kinetic missiles to intercept.
But since kinetic weapons don't use or need any additional guidance or control systems it doesn't change the price that much if you use 1 50 ton missiles or 50 1ton missiles. The easier it is to intercept the attack the more likely that many smaller missiles would be used.
Maybe the key to interstellar war is to ensure the battle is fought in unimportant stars systems near the border and not let enemy squadrons get within jumping distance of the really important worlds.
Imagine a pillar of metal at rest and you shoot a laser at it. You keep firing until it melts and then boils. Due to increased pressure (a gas would expand relative to the more compressed solid/liquid states) it expands. But by how much. It isn't an explosion, just the effect of steam rising. So what is this? 10 cm / second? 1 meter per second? New steam keeps being created and fans out at 1 m/s creating a big cloud. Applying slight pressure on the missile so it changes course a very small amount the other way (a bit of gas pushing against a big solid piece). But this is cumulative so let's say that eventually everything is gaseous spreading out to the side at 1 m/s.
We would add the two vectors. One has the gas travelling on its original course at 5 million meters per second. The other has the gas move sideways 1 meter per second. If it is aimed at a very precise target in orbit this small variation in course could make a difference. But if it is aimed at the center of where the planet will be when the courses intersect, you need a lot of course correction. Earth has a radius of around 6,370 km. Okay, this is a size 8 world and a lot of worlds are smaller but would still want to miss the atmosphere too. Let's say that a 4,000 km course correction is sufficient. To get this correction (a 4 million meter correction) you would need to have boiled off the missile outside of 20 billion km.
Maybe the laser being fired is extremely intense. Kind of a spinal mount weapon, not just a standard starship weapon. Something so powerful it can push starships by firing at them. Something so intense that it turns a chunk of solid metal into a rocket with 2G of thrust over the time you fired at it. If it can boil off hull armor at that speed this would be one scary starship combat weapon (outperforming all spinal mount particle accelerators). But let's say such a super laser is used and you can fire at the target continuously for 1 minute. Such a laser would allow you to intercept the kinetic torpedo up to 2.8 million kilometers out.
If you can build and operate such a laser you still have to hit that moving target for that minute. Leaving aside targeting considerations (hitting a 3 cubic meter target travelling at extreme speeds that has zero emissions), you have to keep it in range for that full minute. What is the range of the laser? Regular starship based weapons (spinal mounts included) seem to cap out at 50,000 km. Can we multiply that by 10, to have a weapon that can fire 500,000 km? (would have an impact on overall tactics if you have defensive weapons that outperform weapons on attacking starships like that, but let's assume we can).
Cool. This 500,000 km range means you can be off to the side a little and fire as the kinetic torpedo passes by because it will take about 200 seconds to cross weapon range (less if the laser platform is moving - which it must have the capability of doing so because it would have to move out to around 1-2 million km out from the planet in a position to defend against the attack).
A less powerful or shorter range laser could be used much farther out (with more space to cover harder to be in position) or (even harder) matching vectors with the missile (starting out near the attacking ships - but way out of weapons range - and accelerating with them so you can be on a similar vector to the torpedo so you have lots of time to just keep firing at it).
Less dependent on having ships in lucky positions, I'm thinking that a wing of heavy fighters (maybe 50-60 tons each) with great sensors and communications equipment (to coordinate with larger vessels that have better sensors) firing tactical nuclear missiles at incoming objects. Such craft can be scrambled and (if your Traveller universe allows) be set up as drones with greater than 6G acceleration. Not useful against enemy capital ships that will most certainly have nuclear dampers but a dead weight kinetic weapon would have no nuclear damper protection. Each fighter can carry multiple (many) missiles such that you can do an overkill spread. (if you fire ten nukes at each kinetic weapon are you guaranteed at least one will hit?) Fighter craft that can be scrambled out when you detect ship(s) accelerating in at an unusual vector (one that doesn't allow turnaround and deceleration to reach planetary orbit). They don't actually launch the nukes unless there are kinetic missiles to intercept.
But since kinetic weapons don't use or need any additional guidance or control systems it doesn't change the price that much if you use 1 50 ton missiles or 50 1ton missiles. The easier it is to intercept the attack the more likely that many smaller missiles would be used.
Maybe the key to interstellar war is to ensure the battle is fought in unimportant stars systems near the border and not let enemy squadrons get within jumping distance of the really important worlds.
I've thought about the points raised about intercepting and deflecting a kinetic weapon. A lot of valid approaches to dealing with a kinetic attack stop being valid when you go beyond some level of mass and velocity. We can look up formulas and crunch numbers of the amount of energy involved but the rules just don't provide much guidance on how this would work so it isn't possible to determine at what point it becomes impossible to intercept the object through regular means (ie. weapons a regular small starship might carry) and at what point it is not even possible to intercept the weapon through extraordinary means.
I mean, I think we can all recognize that if a weapon was coming in at 0.99 of the speed of light that it is virtually impossible to intercept it at even TL 15 because even if you could detect some light or radar reflection off of the weapon from two billion km away there would only be a minute between detection and it hitting.
If the object is coming in at 500 meters per second without maneuvering, interception is certain. How can you miss?
But what about in between.
I have an analogy for the difference between objects at normal ship combat speeds and the extreme velocities described for a strategic kinetic weapon.
Say I have a small metal object, a little piece of lead. I casually toss it at you. I think we can agree that it will bounce off your clothes and, if your clothes are thick and baggy enough (like a down filled coat), you may not even detect it. If you wanted to swat it out of the air as it came in or even catch it), it wouldn't be too difficult (maybe not certain but possible depending on your coordination and skill). . With equipment such as a tennis racket or baseball glove the chance of deflecting or catching it could be significantly improved. Let's say this little piece of lead is like an asteroid that might hit our planet (about 20 km/s) or a space ship travelling at similar speed.
Now, instead of throwing that little ball of lead it is packed into a cartridge loaded into a working replica of a civil war era revolver. I fire this revolver at you. Can you expect:
1) to catch the bullet?
2) to deflect it with a tennis racket?
3) your regular clothes to stop it?
Obviously limitations at TL 7 or 8 do not necessarily apply at TL 14 or 15. But I think some limitations are bound to be there regardless.
There is bound to be a speed that exceeds the ability of a defender to intercept. If 500 km/s isn't fast enough anymore, then 1,000 km/s, or 5,000 or 10,000. If defense systems become better able to target high velocity objects, fire a larger volley mass of weapons and split that mass up into smaller missiles to present many more targets for interception. Attackers will try to stay ahead of the capabilities of defenders.
Trying to defend against kinetic weapons like this seems like the money being blown on strategic missile defense. For all the talk of deploying a missile defense system against ICBMs there has not been a successful test in which the launch time and trajectory of the missile being targeted was not communicated in advance - and even then it isn't something that can be counted on. The American Physical Society (yeah, rocket scientists) analyzed this a few years ago and concluded that the only defense that had a reasonable likelihood of success involved as-yet undeveloped high velocity missiles stationed in low orbit to launch down at ICBMs moments after they launched. To defend against a specific location, such as North Korea, would require seven interceptors spread around the circumference of the earth (low orbits require greater speed and cannot be geosynchronous) in order to have one interceptor ready at all times. So to have 60 interceptors ready would require 420 in orbit. The logical response for an enemy would be to mass-produce ICBMs with dud warheads, and keep building more as each missile costs your enemy more than ten times as much in defensive systems.
Attackers will develop technology and methods of attack to bypass or overwhelm enemy defenses and the nature of technology is that our ability to destroy has already outstripped our ability to defend. The defense of the USA against an ICBM attack is not a hope that some missiles in Europe will be able to intercept anything, it is early detection systems and a sufficient inventory of weapons to ensure the destruction of whoever initiates such an attack.
We can imagine a conventional proxy war in Ukraine between forces backed by Russia or by NATO. But can we imagine NATO forces punching through Russian forces and driving on Moscow? At some point the conflict may threaten one side too much - presenting a possibility of resorting to nuclear weapons. Both sides would seek to keep it from getting to that stage. The political leadership of both sides would be closely involved in the conflict and be in communication with the other side to avoid escalation.
Just so, I think that in the conflicts between the Imperium and the Zhodani I think the primary defense against such strategic bombardment is not nuclear missiles or energy weapons that put capital ship spinal mounts to shame. Even if possible the cost of defending each world would take resources away from offensive capability. I think that it comes down to the best defense being a good offense. It is the shear size and industrial might of each side (ability to produce and deploy many such weapons), the expected resolve to continue a war by similar means if such weapons are unleashed, and natural human reluctance to take the risk of war escalating to that stage.
I mean, I think we can all recognize that if a weapon was coming in at 0.99 of the speed of light that it is virtually impossible to intercept it at even TL 15 because even if you could detect some light or radar reflection off of the weapon from two billion km away there would only be a minute between detection and it hitting.
If the object is coming in at 500 meters per second without maneuvering, interception is certain. How can you miss?
But what about in between.
I have an analogy for the difference between objects at normal ship combat speeds and the extreme velocities described for a strategic kinetic weapon.
Say I have a small metal object, a little piece of lead. I casually toss it at you. I think we can agree that it will bounce off your clothes and, if your clothes are thick and baggy enough (like a down filled coat), you may not even detect it. If you wanted to swat it out of the air as it came in or even catch it), it wouldn't be too difficult (maybe not certain but possible depending on your coordination and skill). . With equipment such as a tennis racket or baseball glove the chance of deflecting or catching it could be significantly improved. Let's say this little piece of lead is like an asteroid that might hit our planet (about 20 km/s) or a space ship travelling at similar speed.
Now, instead of throwing that little ball of lead it is packed into a cartridge loaded into a working replica of a civil war era revolver. I fire this revolver at you. Can you expect:
1) to catch the bullet?
2) to deflect it with a tennis racket?
3) your regular clothes to stop it?
Obviously limitations at TL 7 or 8 do not necessarily apply at TL 14 or 15. But I think some limitations are bound to be there regardless.
There is bound to be a speed that exceeds the ability of a defender to intercept. If 500 km/s isn't fast enough anymore, then 1,000 km/s, or 5,000 or 10,000. If defense systems become better able to target high velocity objects, fire a larger volley mass of weapons and split that mass up into smaller missiles to present many more targets for interception. Attackers will try to stay ahead of the capabilities of defenders.
Trying to defend against kinetic weapons like this seems like the money being blown on strategic missile defense. For all the talk of deploying a missile defense system against ICBMs there has not been a successful test in which the launch time and trajectory of the missile being targeted was not communicated in advance - and even then it isn't something that can be counted on. The American Physical Society (yeah, rocket scientists) analyzed this a few years ago and concluded that the only defense that had a reasonable likelihood of success involved as-yet undeveloped high velocity missiles stationed in low orbit to launch down at ICBMs moments after they launched. To defend against a specific location, such as North Korea, would require seven interceptors spread around the circumference of the earth (low orbits require greater speed and cannot be geosynchronous) in order to have one interceptor ready at all times. So to have 60 interceptors ready would require 420 in orbit. The logical response for an enemy would be to mass-produce ICBMs with dud warheads, and keep building more as each missile costs your enemy more than ten times as much in defensive systems.
Attackers will develop technology and methods of attack to bypass or overwhelm enemy defenses and the nature of technology is that our ability to destroy has already outstripped our ability to defend. The defense of the USA against an ICBM attack is not a hope that some missiles in Europe will be able to intercept anything, it is early detection systems and a sufficient inventory of weapons to ensure the destruction of whoever initiates such an attack.
We can imagine a conventional proxy war in Ukraine between forces backed by Russia or by NATO. But can we imagine NATO forces punching through Russian forces and driving on Moscow? At some point the conflict may threaten one side too much - presenting a possibility of resorting to nuclear weapons. Both sides would seek to keep it from getting to that stage. The political leadership of both sides would be closely involved in the conflict and be in communication with the other side to avoid escalation.
Just so, I think that in the conflicts between the Imperium and the Zhodani I think the primary defense against such strategic bombardment is not nuclear missiles or energy weapons that put capital ship spinal mounts to shame. Even if possible the cost of defending each world would take resources away from offensive capability. I think that it comes down to the best defense being a good offense. It is the shear size and industrial might of each side (ability to produce and deploy many such weapons), the expected resolve to continue a war by similar means if such weapons are unleashed, and natural human reluctance to take the risk of war escalating to that stage.
sideranautae
Mongoose
Meanderer said:There is bound to be a speed that exceeds the ability of a defender to intercept. If 500 km/s isn't fast enough anymore, then 1,000 km/s, or 5,000 or 10,000.
Near speed of light is very difficult if it is suddenly upon the defenders simply because sensors work at light speed. Significantly BELOW c is interceptable using the tech at levels in Traveller for interstellar societies. I already gave the examples.
If one wants to accelerate something near c in Trav you have to start out WAY beyond the distance of Pluto (considering Earth as a target) which gives the defenders MANY days to ready a defense. So, it isn't THAT big of a problem.
If you can give specific technical reasons countering the technical solutions given so far in this thread, I'm all eyes. Otherwise...
Anyway. Since it is takes a long time and a lot of set up to attack a planet with a near c item. The easiest defense is a couple planetoids with m-drives that can be put into a blocking position as there will always be adequate warning to do so.
Laser energy on 50 tons of metal. Theoretically you can do the interception by continuously firing even with a turret based weapon - but how long do you think you need to do this? Because a weapon coming in at you at 5,000 km/s is going to completely cross your weapon range in 20 seconds if you are stationary (weapon range 50,000 km each way for a total firing radius of 100,000 km). If you are moving out to intercept then your velocity comes in to play as your momentum is carrying you in the wrong direction (ie. if you are moving out at 3,000 km/s the time you can fire that laser is now down to 12.5 seconds before the target is out of range again). I really don't think just seconds of firing at an incoming object will be enough with lasers typically in use. The proposed weapon is made entirely of crystaliron. The temperature of the weapon after launch and the boiling point are not defined (imaginary material) but how many megawatts are put into that laser that it is going to so rapidly change the energy state. I've applied physics and done some math. Could a laser interception work on a titanium missile at that speed?
One thing that the math is clear is that the kinetic energy of a 50 ton missile at 5,000km/s 1.25 x 10^18 Joules. A 10 kg cannon ball thrown at that missile to intercept it at 500 km/s has a kinetic energy of 2.5 x 10^12 Joules. Now that is one hell of a cannon ball but, really, it is still quite negligible in relation to what it is trying to intercept. You know, I have the technologicial capability to intercept an oncoming freight train with a rifle. Means I can hit it. Doesn't mean I can stop it.
I do stand corrected on one of my calculations as I further checked facts. I was taking the kinetic energy against 50 tons to create a changed vector. This is an incorrect application of the Law of Momentum Conservation http://en.wikipedia.org/wiki/Momentum. Apologies for not catching this earlier. I'm not a physics major.
The correct calculation for conservation of momentum uses just mass times velocity (momentum, not kinetic energy). The sum of the mass times velocity of the objects colliding must be maintained. So that high velocity cannonball, if it bounces off the oncoming missile at a velocity of 6,000 km/s (faster than the kinetic missile) that leaves 50 tons of incoming mass travelling at 4,998.9 km/s. At an 1,100 m/s difference in velocity, this changes the distance at which the course correction will miss target by more than 4,000 km (missing a medium sized planetary target) to 18 million km out (not the 4 million km I had before). You need to intercept these weapons earlier.
But the assumption of 500 km/s can be adjusted too. Accelerating out from planetary orbit to this interception range at 6G a fighter will reach a velocity of over 1,200 km/s at a range of around 12.5 million km. If this cannon ball bounces off the kinetic missile at a velocity of 8,000 km/s this will slow the kinetic missile down by 1.6 km/s which would be enough to cause it to miss the planet. Of course the time to accelerate out to this interception point is about 5.7 hours. So you need to detect the incoming kinetic missile at a range of over 114 million km. Before you start intercepting that kinetic missile it may be shaped in any shape with a non-reflective coating in order to avoid it being detected. (check my math. Using basic physics formulas here. Could be underestimating what the matter of that exploding cannonball is flying off at. If it flies off at a higher velocity this would cut down the range at which you must intercept the kinetic missile. But how is this not a technical argument about the difficulty of intercepting?).
Note, having craft positioned further out in the system allows an earlier interception but the wider the arc of coverage for stationing system defense craft the more of them you need.
Technical reasons making interception more difficult:
1) trying to detect a very small object that is not emitting any radiation. The rules cover encountering another ship with encounters starting at very long range (between 25,000 and 50,000 km. Other ranges for ship sensors are not provided but clearly sensors are capable of targeting objects up to 50,000 km. Under what rule is a very small object (by spacecraft standards) detected and plotted at 114 million km out, particularly if it has zero emissions.
Having sensor platforms further out extends the range of detection but multiplies the number of sensor platforms as you are covering a much larger area of space. If such a stealth object can be reliably detected at such ranges this would render pretty much all stealth craft described in Mongoose rules as useless for sneaking anyone onto a planet. Something has to change there.
2) physics described above appears to render conventional weapons insufficient to stop the target unless you have an extremely early detection or are just plain lucky enough to have defense craft in the right location. Even that 10kg cannonball that can intercept the kinetic weapon 12 million km out is hitting with the energy of a 3 kiloton explosion. This is obviously beyond the scope of regular Traveller combat. So we are talking nuclear missiles that must be launched to hit a stealth target precisely as it flies by you at incredible speed. What is the range for precision location/targeting? (not just detecting something and getting a rough measure of its velocity, I'm talking about hitting a bullet as it flies at you precision). Nothing in the rules has such precision targeting much beyond weapons range of 50,000 km.
3) rules based argument, even in normal space combat a roll to hit is needed. Sparing some thrust for maneuver means a pilot can make a dodging maneuver for a -2 penalty for the attacker. Not allocating any thrust to maneuver means no dodging so no penalty (but there is no bonus to hit a target that isn't maneuvering). (pages 147-149 of main rulebook).
Further rule reference: High Guard page 75 Spinal weapon attacks. Taking the most sophisticated weapon in your fleet and using the weapon its fire control systems are built around at a 30 ton ship's boat gets you a targeting penalty of -6 and a further size penalty of -3. This -9 penalty would be offset by crew skill (typically +3 to +5) meaning a roll to hit with at least a -4 to hit. Now logically there should be some bonuses added back for taking some time to line up a shot but the point remains that firing at targets that are not maneuvering doesn't mean an automatic hit. Now assume that the -6 penalty is completely waived for being able to line up a shot, there still must be a roll to hit. And this would apply to a small craft moving at 50 km/s.
The rules don't say what to do about a target travelling at 100 times this speed but certainly some penalties would be in order.
Again, I am not saying that it is impossible to intercept a strategic kinetic attack. Only that it is not going to be easy to detect and get an intercept course on the incoming object, and that it is also not easy to hit it. The rules do not indicate that interception is automatic. Also, for reasons described above based on Physics, it is not simply enough to hit the incoming object. You need to significantly alter its course. That can take an awful lot of energy.
To summarize:
1) stealth craft in Traveller indicate that sensors are not perfect in detecting all objects within many millions of kilometers.
2) starship combat does not allow automatic hits of non-maneuvering targets (must still roll to hit) so the rules don't indicate that you can automatically hit the oncoming object
3) Physics shows that the energy put out by conventional Traveller weapons are insufficient (other than missiles intercepting with immense kinetic energy) and even then the interception must be made beyond a range of millions of kilometers to sufficiently affect the kinetic weapon to make it miss. Intercepting cannot be casually done from orbit - it takes very early detection, significant time and energy to achieve an interception vector and hitting a very small target with pinpoint precision with a firing window in microseconds. (supports additional penalties over and above those that would apply in regular space combat.)
Additional point. If it is not certain to hit a 30 ton ship's boat that is not maneuvering, what additional penalties for hitting a stealthed target, 3 tons in size, that is difficult to detect. And if they launch it with a big load of reflective chaff (okay, early detection problem solved) doesn't this exacerbate the problem of hitting the kinetic weapons as it should make it much more difficult to get an exact target fix).
I think I've given substantial technical proof that intercepting a kinetic weapon is not certain. So please tell me where in the rules it says that regular weapons will stop any incoming kinetic object.
One thing that the math is clear is that the kinetic energy of a 50 ton missile at 5,000km/s 1.25 x 10^18 Joules. A 10 kg cannon ball thrown at that missile to intercept it at 500 km/s has a kinetic energy of 2.5 x 10^12 Joules. Now that is one hell of a cannon ball but, really, it is still quite negligible in relation to what it is trying to intercept. You know, I have the technologicial capability to intercept an oncoming freight train with a rifle. Means I can hit it. Doesn't mean I can stop it.
I do stand corrected on one of my calculations as I further checked facts. I was taking the kinetic energy against 50 tons to create a changed vector. This is an incorrect application of the Law of Momentum Conservation http://en.wikipedia.org/wiki/Momentum. Apologies for not catching this earlier. I'm not a physics major.
The correct calculation for conservation of momentum uses just mass times velocity (momentum, not kinetic energy). The sum of the mass times velocity of the objects colliding must be maintained. So that high velocity cannonball, if it bounces off the oncoming missile at a velocity of 6,000 km/s (faster than the kinetic missile) that leaves 50 tons of incoming mass travelling at 4,998.9 km/s. At an 1,100 m/s difference in velocity, this changes the distance at which the course correction will miss target by more than 4,000 km (missing a medium sized planetary target) to 18 million km out (not the 4 million km I had before). You need to intercept these weapons earlier.
But the assumption of 500 km/s can be adjusted too. Accelerating out from planetary orbit to this interception range at 6G a fighter will reach a velocity of over 1,200 km/s at a range of around 12.5 million km. If this cannon ball bounces off the kinetic missile at a velocity of 8,000 km/s this will slow the kinetic missile down by 1.6 km/s which would be enough to cause it to miss the planet. Of course the time to accelerate out to this interception point is about 5.7 hours. So you need to detect the incoming kinetic missile at a range of over 114 million km. Before you start intercepting that kinetic missile it may be shaped in any shape with a non-reflective coating in order to avoid it being detected. (check my math. Using basic physics formulas here. Could be underestimating what the matter of that exploding cannonball is flying off at. If it flies off at a higher velocity this would cut down the range at which you must intercept the kinetic missile. But how is this not a technical argument about the difficulty of intercepting?).
Note, having craft positioned further out in the system allows an earlier interception but the wider the arc of coverage for stationing system defense craft the more of them you need.
Technical reasons making interception more difficult:
1) trying to detect a very small object that is not emitting any radiation. The rules cover encountering another ship with encounters starting at very long range (between 25,000 and 50,000 km. Other ranges for ship sensors are not provided but clearly sensors are capable of targeting objects up to 50,000 km. Under what rule is a very small object (by spacecraft standards) detected and plotted at 114 million km out, particularly if it has zero emissions.
Having sensor platforms further out extends the range of detection but multiplies the number of sensor platforms as you are covering a much larger area of space. If such a stealth object can be reliably detected at such ranges this would render pretty much all stealth craft described in Mongoose rules as useless for sneaking anyone onto a planet. Something has to change there.
2) physics described above appears to render conventional weapons insufficient to stop the target unless you have an extremely early detection or are just plain lucky enough to have defense craft in the right location. Even that 10kg cannonball that can intercept the kinetic weapon 12 million km out is hitting with the energy of a 3 kiloton explosion. This is obviously beyond the scope of regular Traveller combat. So we are talking nuclear missiles that must be launched to hit a stealth target precisely as it flies by you at incredible speed. What is the range for precision location/targeting? (not just detecting something and getting a rough measure of its velocity, I'm talking about hitting a bullet as it flies at you precision). Nothing in the rules has such precision targeting much beyond weapons range of 50,000 km.
3) rules based argument, even in normal space combat a roll to hit is needed. Sparing some thrust for maneuver means a pilot can make a dodging maneuver for a -2 penalty for the attacker. Not allocating any thrust to maneuver means no dodging so no penalty (but there is no bonus to hit a target that isn't maneuvering). (pages 147-149 of main rulebook).
Further rule reference: High Guard page 75 Spinal weapon attacks. Taking the most sophisticated weapon in your fleet and using the weapon its fire control systems are built around at a 30 ton ship's boat gets you a targeting penalty of -6 and a further size penalty of -3. This -9 penalty would be offset by crew skill (typically +3 to +5) meaning a roll to hit with at least a -4 to hit. Now logically there should be some bonuses added back for taking some time to line up a shot but the point remains that firing at targets that are not maneuvering doesn't mean an automatic hit. Now assume that the -6 penalty is completely waived for being able to line up a shot, there still must be a roll to hit. And this would apply to a small craft moving at 50 km/s.
The rules don't say what to do about a target travelling at 100 times this speed but certainly some penalties would be in order.
Again, I am not saying that it is impossible to intercept a strategic kinetic attack. Only that it is not going to be easy to detect and get an intercept course on the incoming object, and that it is also not easy to hit it. The rules do not indicate that interception is automatic. Also, for reasons described above based on Physics, it is not simply enough to hit the incoming object. You need to significantly alter its course. That can take an awful lot of energy.
To summarize:
1) stealth craft in Traveller indicate that sensors are not perfect in detecting all objects within many millions of kilometers.
2) starship combat does not allow automatic hits of non-maneuvering targets (must still roll to hit) so the rules don't indicate that you can automatically hit the oncoming object
3) Physics shows that the energy put out by conventional Traveller weapons are insufficient (other than missiles intercepting with immense kinetic energy) and even then the interception must be made beyond a range of millions of kilometers to sufficiently affect the kinetic weapon to make it miss. Intercepting cannot be casually done from orbit - it takes very early detection, significant time and energy to achieve an interception vector and hitting a very small target with pinpoint precision with a firing window in microseconds. (supports additional penalties over and above those that would apply in regular space combat.)
Additional point. If it is not certain to hit a 30 ton ship's boat that is not maneuvering, what additional penalties for hitting a stealthed target, 3 tons in size, that is difficult to detect. And if they launch it with a big load of reflective chaff (okay, early detection problem solved) doesn't this exacerbate the problem of hitting the kinetic weapons as it should make it much more difficult to get an exact target fix).
I think I've given substantial technical proof that intercepting a kinetic weapon is not certain. So please tell me where in the rules it says that regular weapons will stop any incoming kinetic object.
sideranautae
Mongoose
Meanderer said:Laser energy on 50 tons of metal. Theoretically you can do the interception by continuously firing even with a turret based weapon - but how long do you think you need to do this?
Hit it with a nuc while a couple days away. I already gave that workable solution way back. And, STILL not countered as a viable solution using basic physics.
Done.
Planet defense sized IR 'scopes ARE going to detect every operational ship within the solar system. That's inescapable physics. DAYS and DAYS of travel at that power output seals the fate of that ship. The CRB nailed it when it first sited it.
If one wants to accelerate something near c in Trav you have to start out WAY beyond the distance of Pluto (considering Earth as a target) which gives the defenders MANY days to ready a defense. So, it isn't THAT big of a problem.
So, now we are detecting ships trillions of km away? I guess there really is no such thing as stealth.
Jump out far enough and you can finish your acceleration before any enemy ship has time to accelerate out to meet you. Carry enough fuel for two jumps and you will jump out before you can come under attack.
If you can get an object up to .99 c there is no defense (other than some magical Ancient device that can detect and disintegrate the incoming object).
If you can target and hit something like that then there shouldn't be any rolls to hit in starship combat (just determine damage when everyone fires).
See my previous e-mail for why detecting the attack is only part of the problem in mounting a defense.
A correction on the precision firing within microseconds.
Even if you have exact information on the target object's position and speed, if you are more than 0.00001 seconds off on your planned firing time you will miss. If you fire an energy weapon at one very precise point in space, you will hit it for at most 0.00001 of a second. Are you able to change the bearing on your weapon to track a target this fast? (and I'm talking about the 5,000 km/s object here, not some insane object at near light speed). Are railguns or missile launch tubes (and missile propulsion systems) so accurate that you can hit a target point in space that is less than 1 meter in profile at that precise a point in time?
sideranautae
Mongoose
Meanderer said:So, now we are detecting ships trillions of km away? I guess there really is no such thing as stealth.
Sure. We can do it today (TL 7) with off the shelf (civilian) components costing less than $5,000. Why wouldn't a planetary gov do it at TL's 10-15? I don't understand your reasoning on that.
The IR 'scopes our current gov has would spot a ship out to the Ort cloud easily...
Meanderer said:Jump out far enough and you can finish your acceleration before any enemy ship has time to accelerate out to meet you.
Why would one want to meet the thrusting ship? Just track the incoming object. All you have to know is the ships vector before jump and you'll always know the exact location of its dropped impacter..
Also, if you want to go by canon, LONG ago Marc correctly rules and wrote in da rules that a ship that maintains a course without maneuvering is auto hit. It was in response to people using Black globes and thinking that because they were invisible they couldn't be targeted. Marc correctly stated that if you were observed right before you went to black globe, your position can be auto calculated and auto hit because you aren't changing vector.. No to hit roll needed.
Cool comments. We are getting somewhere.
Is this confusing eventual detection (as in every once in a while a new significant item is spotted and logged)? We get people identifying comets and asteroids that are drifting through (in long elliptical orbits in and out or are on their way spiraling in towards the sun). Are you sure that people with $5,000 gear are identifying objects out beyond the asteroid belt? Are they logging every asteroid of less than a meter in diameter? Will every small object be tracked even at TL 15? Maybe but there are an awful lot of small rocks and chunks of ice out there. And the telescope needs to be pointed in the right direction. If you can coat the ship and its torpedo(es) to be non-reflective that civilian gear wouldn't show much.
Sure, a rocket (fusion or chemical) will project a lot of heat (and you can tell if it is accelerating or decelerating based on this). But is a Traveller starship radiating heat. You just need to have something you can sink the ship's heat into. The fusion reactor is generating heat but this is getting turned into energy which is lost into the maneuver drive. I can't recall where but I read something recently about cutting emissions from a ship including heat emissions. And once you just have the kinetic weapon it could be quite cold when launched. It has no heat sources onboard because it is a solid object so once acceleration ceases it would just be a cold dead object. I know about active radar emissions, transponders and (close enough) neutrino sensors. Not sure that thermal imagery works that well. Interested if there is a Traveller source I am missing. This is intriguing. Please tell me more.
not quite exact location. it may continue accelerating for a while going ahead of the kinetic missile and then give itself a bit of thrust on the turnaround so it will miss the kinetic missile while decelerating. So is that kinetic missile going 5,000,418 m/s or just 4,999,992 m/s. You detect the ships. Figuring out that they dropped something maybe predicted from its course but the kinetic missiles may be coated to not reflect light or radar, and won't be an active heat source either so where exactly did they drop the torpedoes?
Intercepting the ships before they launch disrupts their vector. If you can make them alter course or knock out their maneuver drives you may prevent the kinetic missile attack. Remember that the ship isn't heading for the planet, but for where the planet will be at a particular time for a planned intersection with the kinetic weapon. 22 minutes or 4,000 km may cause the course to be all wrong. Also, for all their ability to maneuver the ship is a bigger target that is easier to detect (hey! neutrino emissions!) . And it probably takes less to knock out the ship's critical systems than it does to deflect the kinetic weapon.
Okay, a rule applied to ships already detected and within weapons range (and therefore within the really effective range of sensors) that suddenly disappears. Not much trouble to get a pretty good idea of where it is. And you don't have to hit the actual ship, but the wider sphere of the black globe (a shot that might otherwise have missed the ship could hit where the black globe is).
But what do we make of this rule. Is this like a magic bow of never missing? This is a science fiction game and we should try to keep the science in mind.
Consider a man walking across a field, and an expert shot with a rifle intending to shoot him (a woman, for the sake of this case). The man walks out of the trees and continues across the field at a steady walking pace (5 km/hour) while the woman takes aim and drops him. I mean, would we say there is much of any chance of missing here? He's not dodging or anything. So the markswoman can automatically hit him because she saw him, is tracking him closely, and he isn't evading. Simple.
So if she tries to shoot a rocket shooting across the field at 500 km/hour she must automatically hit because she can see it, can estimate it's course and it isn't evading. Right. Um, but that really doesn't make sense, does it.
Of course with more sophisticated weapons and certainly with higher tech levels that 500 km/hour rocket may be an easy target. At TL 15 certainly. But we weren't talking about a rocket like that. What if the "rocket" is travelling at 17,999,971 km/hour. Being half a meter off on the position of a fighter or ship's boat will probably still mean a hit. But being a half meter off on this zero-emission object probably means you miss.
Even being able to track it doesn't mean you can precisely hit it. The best shot is being as close as you can to its line of travel which may be more difficult than it sounds. An intercepting ship would need to get onto the course of the kinetic object and ditch the momentum that got it there. This can be done as you accelerate towards the object, gradually correcting the course but will depend on exact information about it's position and course. Not just that there is a torpedo coming in but being able to tell the latitude and longitude of where it will hit down to the centimeter?
Not that precise? Well as much information you have the better. Trying to hit it from the side is the real crapshoot. At the speed it is going it will be really hard to line up that precise shot. Even if you have an exact position and velocity the shot must be timed incredibly close - because a slight difference in time means it is somewhere else when the shot gets there. Consider the volume it is occupying (a cylinder 1/2 meter in diameter and 16 m long). You are to hit it at x time. At 0.0000032 seconds no part of the object is in that volume anymore.
We are talking a level of precision never needed in normal starship combat. If a ship is accelerating at 6G and you are .1 seconds late shooting at it you probably still hit it.
And unless you are shooting exactly down its path there is at least some of this margin to miss regardless. It's coming at you along its axis, a circle a half meter in diameter. Your ship may be lined up exactly on its course but does that mean your turrets are lined up?
I figure that this is not exact but higher tech level defense systems can give the intercepting craft some form of boost. To go back to my analogy, systems designed to shoot at that man running across the field (which can certainly hit him if he only walks in a straight line) have a shot at hitting that rocket flying across the field only because of the boost provided by the defense systems but I really can't see this as being the same as attacking a coasting ship with only a small relative velocity differential.
Had a thought about those nukes. And this bothers me because I really liked the idea of trying to intercept these monstrosities with nukes. How long does the nuke need to detonate? I understand the nuclear reaction takes nanoseconds but the impact with the missile would be instantaneous and catastrophic. I figure the nuke needs some sensors to target anyway and would have special programming to trigger its detonation before impact to try to detonate close too the kinetic weapon but before impact - but this is another thing that can go wrong, isn't it? Too soon and there is wasted energy. Too late and the nuke is blown to bits before it can detonate.
Besides, which is more fun in an RPG:
1) kinetic weapons are inbound. Who cares. The navy can intercept them automatically. or
2) kinetic weapons are inbound. All ships with missile launchers that are able to match this vector are requested to divert and try to intercept (having the players make some hard dice rolls and hope they can make an interception for... a reward? a knighthood? fame? popularity? a chance to make some new connections and get another job? with a mad scramble of all available ships trying to reach an intercept course?
Exactly. A compact missile capable of delivering massive energy. Divert its course far enough out and it will miss.Hit it with a nuc while a couple days away.
Sure. We can do it today (TL 7) with off the shelf (civilian) components costing less than $5,000.
Is this confusing eventual detection (as in every once in a while a new significant item is spotted and logged)? We get people identifying comets and asteroids that are drifting through (in long elliptical orbits in and out or are on their way spiraling in towards the sun). Are you sure that people with $5,000 gear are identifying objects out beyond the asteroid belt? Are they logging every asteroid of less than a meter in diameter? Will every small object be tracked even at TL 15? Maybe but there are an awful lot of small rocks and chunks of ice out there. And the telescope needs to be pointed in the right direction. If you can coat the ship and its torpedo(es) to be non-reflective that civilian gear wouldn't show much.
.The IR 'scopes our current gov has would spot a ship out to the Ort cloud easily...
Sure, a rocket (fusion or chemical) will project a lot of heat (and you can tell if it is accelerating or decelerating based on this). But is a Traveller starship radiating heat. You just need to have something you can sink the ship's heat into. The fusion reactor is generating heat but this is getting turned into energy which is lost into the maneuver drive. I can't recall where but I read something recently about cutting emissions from a ship including heat emissions. And once you just have the kinetic weapon it could be quite cold when launched. It has no heat sources onboard because it is a solid object so once acceleration ceases it would just be a cold dead object. I know about active radar emissions, transponders and (close enough) neutrino sensors. Not sure that thermal imagery works that well. Interested if there is a Traveller source I am missing. This is intriguing. Please tell me more.
Well, there is a key word. Operational. Does that mean a dead ship with no working power plant may not be detected. Because if we are talking about a ship that is maneuvering under power as operational, that doesn't necessarily describe a relatively small (3 displacement tons) kinetic missile. It's not operating. It just is. Again, if it is cooled before launch it isn't going to pick up that much heat on its way in so what thermal signature would the missile have. And if the launching ship did its acceleration far outside of the solar system is it really going to be detected either? How do the stealth coatings (page 106 of the rules) and the stealth jump drives described in Book 2 (High Guard) fit in with this?Planet defense sized IR 'scopes ARE going to detect every operational ship within the solar system.
Why would one want to meet the thrusting ship? Just track the incoming object. All you have to know is the ships vector before jump and you'll always know the exact location of its dropped impacter.
not quite exact location. it may continue accelerating for a while going ahead of the kinetic missile and then give itself a bit of thrust on the turnaround so it will miss the kinetic missile while decelerating. So is that kinetic missile going 5,000,418 m/s or just 4,999,992 m/s. You detect the ships. Figuring out that they dropped something maybe predicted from its course but the kinetic missiles may be coated to not reflect light or radar, and won't be an active heat source either so where exactly did they drop the torpedoes?
Intercepting the ships before they launch disrupts their vector. If you can make them alter course or knock out their maneuver drives you may prevent the kinetic missile attack. Remember that the ship isn't heading for the planet, but for where the planet will be at a particular time for a planned intersection with the kinetic weapon. 22 minutes or 4,000 km may cause the course to be all wrong. Also, for all their ability to maneuver the ship is a bigger target that is easier to detect (hey! neutrino emissions!) . And it probably takes less to knock out the ship's critical systems than it does to deflect the kinetic weapon.
.Also, if you want to go by canon, LONG ago Marc correctly rules and wrote in da rules that a ship that maintains a course without maneuvering is auto hit. It was in response to people using Black globes and thinking that because they were invisible they couldn't be targeted. Marc correctly stated that if you were observed right before you went to black globe, your position can be auto calculated and auto hit because you aren't changing vector.. No to hit roll needed.
Okay, a rule applied to ships already detected and within weapons range (and therefore within the really effective range of sensors) that suddenly disappears. Not much trouble to get a pretty good idea of where it is. And you don't have to hit the actual ship, but the wider sphere of the black globe (a shot that might otherwise have missed the ship could hit where the black globe is).
But what do we make of this rule. Is this like a magic bow of never missing? This is a science fiction game and we should try to keep the science in mind.
Consider a man walking across a field, and an expert shot with a rifle intending to shoot him (a woman, for the sake of this case). The man walks out of the trees and continues across the field at a steady walking pace (5 km/hour) while the woman takes aim and drops him. I mean, would we say there is much of any chance of missing here? He's not dodging or anything. So the markswoman can automatically hit him because she saw him, is tracking him closely, and he isn't evading. Simple.
So if she tries to shoot a rocket shooting across the field at 500 km/hour she must automatically hit because she can see it, can estimate it's course and it isn't evading. Right. Um, but that really doesn't make sense, does it.
Of course with more sophisticated weapons and certainly with higher tech levels that 500 km/hour rocket may be an easy target. At TL 15 certainly. But we weren't talking about a rocket like that. What if the "rocket" is travelling at 17,999,971 km/hour. Being half a meter off on the position of a fighter or ship's boat will probably still mean a hit. But being a half meter off on this zero-emission object probably means you miss.
Even being able to track it doesn't mean you can precisely hit it. The best shot is being as close as you can to its line of travel which may be more difficult than it sounds. An intercepting ship would need to get onto the course of the kinetic object and ditch the momentum that got it there. This can be done as you accelerate towards the object, gradually correcting the course but will depend on exact information about it's position and course. Not just that there is a torpedo coming in but being able to tell the latitude and longitude of where it will hit down to the centimeter?
Not that precise? Well as much information you have the better. Trying to hit it from the side is the real crapshoot. At the speed it is going it will be really hard to line up that precise shot. Even if you have an exact position and velocity the shot must be timed incredibly close - because a slight difference in time means it is somewhere else when the shot gets there. Consider the volume it is occupying (a cylinder 1/2 meter in diameter and 16 m long). You are to hit it at x time. At 0.0000032 seconds no part of the object is in that volume anymore.
We are talking a level of precision never needed in normal starship combat. If a ship is accelerating at 6G and you are .1 seconds late shooting at it you probably still hit it.
And unless you are shooting exactly down its path there is at least some of this margin to miss regardless. It's coming at you along its axis, a circle a half meter in diameter. Your ship may be lined up exactly on its course but does that mean your turrets are lined up?
I figure that this is not exact but higher tech level defense systems can give the intercepting craft some form of boost. To go back to my analogy, systems designed to shoot at that man running across the field (which can certainly hit him if he only walks in a straight line) have a shot at hitting that rocket flying across the field only because of the boost provided by the defense systems but I really can't see this as being the same as attacking a coasting ship with only a small relative velocity differential.
Had a thought about those nukes. And this bothers me because I really liked the idea of trying to intercept these monstrosities with nukes. How long does the nuke need to detonate? I understand the nuclear reaction takes nanoseconds but the impact with the missile would be instantaneous and catastrophic. I figure the nuke needs some sensors to target anyway and would have special programming to trigger its detonation before impact to try to detonate close too the kinetic weapon but before impact - but this is another thing that can go wrong, isn't it? Too soon and there is wasted energy. Too late and the nuke is blown to bits before it can detonate.
Besides, which is more fun in an RPG:
1) kinetic weapons are inbound. Who cares. The navy can intercept them automatically. or
2) kinetic weapons are inbound. All ships with missile launchers that are able to match this vector are requested to divert and try to intercept (having the players make some hard dice rolls and hope they can make an interception for... a reward? a knighthood? fame? popularity? a chance to make some new connections and get another job? with a mad scramble of all available ships trying to reach an intercept course?
sideranautae said:The IR 'scopes our current gov has would spot a ship out to the Ort cloud easily...
Hum, not really, we could make that scope, but we aren't gonna spend the money. Don't get me wrong the are plenty of IR spectrum instruments looking out, it just a matter of resolution and probably a lot of confusing Thermographs with Infrared range sensors which are related but different types of instruments.
Thinking about the whole automatic hitting of non-maneuvering targets.
If that is the big issue, it can be resolved simply by building a high-thrust/maneuverability ship's boat under robot control around the torpedo. Just need sensors, a computer, power plant, maneuver drives and a maximum of one week of fuel. Need it to handle the tonnage payload of the missile even though it's volume is much less.
This way the attacking warships don't even need to stick around. They can launch as soon as they have located the planet and jump out as soon after as their jump drives are ready. The missile "boats" are different than regular missiles and torpedoes as they lack the limited burn time from chemical rockets - they can put thrust into movement or maneuver as long as the power plant continues to operate.
They thrust up to the speed they need for their attack and then coast along unless potential intercepting objects are detected and then maneuver to avoid them. As they are putting their full 6G into maneuvering, they will be fairly hard to hit even with their robot control) and unless they are continuously evading attacking ships and missiles they will have plenty of time to course correct, if it is even needed.
Full thrust in any one direction can result in a velocity change of 21 km/s and/or some change in the vector. This can cause a miss if done even one million km out, but the whole point of maneuvering is that the ship not just thrust in one direction so the net effect of the maneuvering will most likely be less and even a couple of million km out there could be a full turn to correct. Even then, there would be a calculated point where the cost/benefit of maneuvering goes down to the point that it is better to eject the missile and let the "boat" and kinetic spear be two separate objects for interception. This makes the weapon more expensive but could prevent the effective interception of the weapon at any range where deflection is reasonably possible.
I still think such weapons would be developed and tested to "show what we can do", and then be held as a deterrent for others trying such attacks. Human nature generally runs against governments using such weapons. Terrorists still may.
Dangerous weapons.
If that is the big issue, it can be resolved simply by building a high-thrust/maneuverability ship's boat under robot control around the torpedo. Just need sensors, a computer, power plant, maneuver drives and a maximum of one week of fuel. Need it to handle the tonnage payload of the missile even though it's volume is much less.
This way the attacking warships don't even need to stick around. They can launch as soon as they have located the planet and jump out as soon after as their jump drives are ready. The missile "boats" are different than regular missiles and torpedoes as they lack the limited burn time from chemical rockets - they can put thrust into movement or maneuver as long as the power plant continues to operate.
They thrust up to the speed they need for their attack and then coast along unless potential intercepting objects are detected and then maneuver to avoid them. As they are putting their full 6G into maneuvering, they will be fairly hard to hit even with their robot control) and unless they are continuously evading attacking ships and missiles they will have plenty of time to course correct, if it is even needed.
Full thrust in any one direction can result in a velocity change of 21 km/s and/or some change in the vector. This can cause a miss if done even one million km out, but the whole point of maneuvering is that the ship not just thrust in one direction so the net effect of the maneuvering will most likely be less and even a couple of million km out there could be a full turn to correct. Even then, there would be a calculated point where the cost/benefit of maneuvering goes down to the point that it is better to eject the missile and let the "boat" and kinetic spear be two separate objects for interception. This makes the weapon more expensive but could prevent the effective interception of the weapon at any range where deflection is reasonably possible.
I still think such weapons would be developed and tested to "show what we can do", and then be held as a deterrent for others trying such attacks. Human nature generally runs against governments using such weapons. Terrorists still may.
Dangerous weapons.
One way to defeat IR is quite old-fashioned - just come in to your target from the direction of the sun. This will defeat an neutrino detection because the sun it's generating neutrino's. With the proper placement on your hull of IR generators you could change your heat signature to be the same as the sun's. This would defeat most passive sensors at your target. To defeat this sort of thing would require placement of sensors that track things obliquely, and even then depending on the location of the sensor it may still get spoofed.
If you want to whack a world it's not hard. Jump a few hundred AU from your target, accelerate for 30 days, release your solid penetrator rounds and leave. They will coast all the way to your target with zero emissions and be impossible to stop.
The only thing stopping the various political entities from planet busting is that if you do it to them, they'll do it to you. And everybody is vulnerable to the same thing, so unless you as a political entity have a death wish, it's not a tactic that will ever be used.
If you want to whack a world it's not hard. Jump a few hundred AU from your target, accelerate for 30 days, release your solid penetrator rounds and leave. They will coast all the way to your target with zero emissions and be impossible to stop.
The only thing stopping the various political entities from planet busting is that if you do it to them, they'll do it to you. And everybody is vulnerable to the same thing, so unless you as a political entity have a death wish, it's not a tactic that will ever be used.
sideranautae
Mongoose
phavoc said:One way to defeat IR is quite old-fashioned - just come in to your target from the direction of the sun.
Unfortunately that won't work either. When using an IR 'scope while pointed towards the sun they would use an occlusion filter which still allows detection of something in the range of a ships temp sig to be easily seen. Of course this is current tech that will only improve as you move up to Trav interstellar TL ranges...
One way to defeat IR is quite old-fashioned - just come in to your target from the direction of the sun.
Unfortunately that won't work either. When using an IR 'scope while pointed towards the sun they would use an occlusion filter which still allows detection of something in the range of a ships temp sig to be easily seen. Of course this is current tech that will only improve as you move up to Trav interstellar TL ranges...
Sensors will become more sensitive as tech level increases. This will allow smaller targets to be detected. Variables will be: size of object, distance from the star (objects closer to the star will be harder to detect than those further away), and how narrow the scan is. I think scanners looking at a particular area of the star's surface are much more likely to pick up the difference (noting something different than normal variations in the star's surface temp.) There is a lot of surface to scan on a star so a very small target may remain hidden where a capital ship sized target will not.
I think such a position might also not show up on neutrino scans because the neutrinos being generated by the power plant will be less than the neutrinos coming off the star, and the star's emissions are not constant so a ship in such a position would fall within normal variation of neutrino emissions.
The biggest issue is maintaining an orbit to stay in such a position. An orbital sensor will be moving with its planet (so maybe 30 km/second). The position will only help you in that one direction anyway and if you don't stay in the right orbit you will eventually no longer have the star behind you.
Of course a really important star system such as Rhylanor in the Spinward Marches will have resources for multiple sensor stations and will want to know what is going on on the far side of the star as well so they may maintain sensor stations each a 90 degree arc ahead or behind the planet. These would pick up a ship between the planet and the star from the side.
Another problem of hiding between the star and the planet is how did you get there? not much room to jump in without being in the 100 diameter limit of the star and if you maneuver in there the system sensors may already have picked you up and been tracking you. If they are already watching you it will be easer to narrow down where to scan. This will allow tracking to take place at a lower tech level than what is needed to do a detection of something not previously known.
I think a better way to hide from IR sensors is to control emissions. This is similar to the IR damping that goes into combat armour or battle dress where the wearer matches background heat sources to essentially be invisible in the IR spectrum (making IR sights useless). This is bound to be imperfect on a moving vessel but the biggest defense is to not have been detected yet. Scanning a huge arc of space is difficult. Even TL 15 sensors may be incapable of scanning a huge arc of space with precision to detect a small target really far out. If they focus sensors in a particular narrow arc the chance of detection of vessels in that arc goes up substantially but which narrow arc. I doubt it will be practical to do a narrow passive scan in every direction - but maybe some really paranoid star system is really willing to go through the expense of having several million sophisticated passive sensors going constantly in order to multiply the chance of early detection.
sideranautae
Mongoose
Meanderer said:Sensors will become more sensitive as tech level increases. This will allow smaller targets to be detected. Variables will be: size of object, distance from the star (objects closer to the star will be harder to detect than those further away), and how narrow the scan is. I think scanners looking at a particular area of the star's surface are much more likely to pick up the difference (noting something different than normal variations in the star's surface temp.) There is a lot of surface to scan on a star so a very small target may remain hidden where a capital ship sized target will not.
A target the size of the space shuttle currently takes about 5-10 minutes to scan for if in front of the sun (and around that temp.) and you are scanning from the distance of Earth. Scanning is done by degree of arc. If it was REALLY close to the surface of the sun (corona distance) it could take longer but the ship would get vaporized in the process.
Yes, on neutrinos. I believe you are quite correct. Anything coming out of the relatively puny PP gets overwhelmed and probably is indiscernible.
For an advanced systems (their defenses) will entail having sensors ALL over the solar system. Including out to at least Ort cloud distances. Any ship will be detected rather quickly if within the star system. There will be no planet to hide behind as there will be no "behind"...
It would also be easy enough to spoof IR sensors. We can do that today.
A defender will never have enough resources to protect every target in a system from attack. Plus there is a massive investment in sensor infrastructure that would have to be made, not to mention the cost of maintaining it. There is never enough money in the Imperial budget to fully pay for all the needs of the Imperial armed forces, let alone individual planets and colonies.
A defender will never have enough resources to protect every target in a system from attack. Plus there is a massive investment in sensor infrastructure that would have to be made, not to mention the cost of maintaining it. There is never enough money in the Imperial budget to fully pay for all the needs of the Imperial armed forces, let alone individual planets and colonies.
A defender will never have enough resources to protect every target in a system from attack. Plus there is a massive investment in sensor infrastructure that would have to be made, not to mention the cost of maintaining it. There is never enough money in the Imperial budget to fully pay for all the needs of the Imperial armed forces, let alone individual planets and colonies.
I think this is the nature of improving technology. We've seen this in the continued development of aircraft and missiles in both an offensive and defensive role - and the fortunes spent on trying to develop a defense against ballistic missiles (and still failing to develop a workable ABM weapon.), with an expectation that even a working defense will cost more than ten times the cost of the ICBMs it hopes to defend against. If your enemy is constrained by how many nuclear warheads can be developed, you can expect a lot of dead warhead ICBMs to be developed. The advantage remains with the attacker.
And this is compounded by having many key worlds to defend while your enemy can concentrate the offensive capability at each one in turn. If you build a defensive system that can defend against a volley of 100 kinetic weapons, expect your enemy to demonstrate a capability of sending 400 at you all at once.
A more effective defense for the Imperium would be to make no effort to defend against such a substantial attack but to demonstrate an even greater ability to retaliate - as the enemy would face the same problems in trying to present a defense. Ultimately, this may serve as a further incentive for Imperial membership as a world alone may be threatened by such attacks whereas an Imperial world may be covered by a threat of retaliation that an aggressor will be reluctant to test.
sideranautae
Mongoose
Meanderer said:And this is compounded by having many key worlds to defend while your enemy can concentrate the offensive capability at each one in turn. If you build a defensive system that can defend against a volley of 100 kinetic weapons, expect your enemy to demonstrate a capability of sending 400 at you all at once.
Very unlikely as it is easier and cheaper to jump into 100D range and bombard with 10 or 100X that amount of nuc missiles/torps.
Trying to spend the set up time (takes MANY days after jumping in at edge of system) and ships to send 400 rocks is stupid use of ships.
Very unlikely as it is easier and cheaper to jump into 100D range and bombard with 10 or 100X that amount of nuc missiles/torps.
Trying to spend the set up time (takes MANY days after jumping in at edge of system) and ships to send 400 rocks is stupid use of ships.
The numbers I crunched show that projectiles going 5,000 km/second will hit with the force of nuclear weapons. A velocity of 5,000 km/s can be achieved from a stationary position in about 1 day at 6G (not many days). (If the attacking vessel has weak maneuver drives like the Lightning Class cruisers - just 2G - then it would take three days to reach 5,000 km/s. Not sure if 3 days counts as "many".)
Stand-off kinetic attacks allow an attacking vessel to achieve a launch vector, launch, decelerate to achieve safe distance from the kinetic weapons (outside of their 100 diameter limit) and jump out while the missiles continue on target. All this requires is a high enough jump drive rating and sufficient fuel for multiple jumps. These ships will also be able to jump away if they see that they will be intercepted before getting in a launch position.
To jump in closer to a major world will requires either an ability to stand on the line of battle against the system defenses with reasonable certainty of being able to overwhelm them. Otherwise, the attacking ships will need an ability to escape (extra fuel enough for another jump). But the more fuel you carry the less able you are to stand on the line of battle against fleet monitors that don't have/need jump drives.
With nukes, you don't have to spend the few days reaching an attack vector - just a few hours from jumping in and matching vector with the planet's orbit (depends on how much early/late you arrive from jump the planet may not be there yet or may have already passed our emergence point). But lower velocity missiles will be easier to intercept and nuclear attacks can be neutralized by planetary based nuclear dampers. Kinetic weapons coming in at very high velocity (such as 5,000 km/s will be harder to hit and even harder to neutralize - as they must be deflected from far out to make them miss; nuclear dampers do nothing against kinetic energy and shattering them at close range just means that the planet gets hit with 300 megaton gravel).
I have been assuming an attack on a high-population industrialized very high-tech world (TL 15). At lower tech levels or industrial capability, nuclear damper protection may not be as established and system defenses will be weaker. Easier for a high-tech navy to fight its way into a position to launch ordnance against the planet, and greater chance that nuclear weapons will hit and be effective.
Meanderer said:Easier for a high-tech navy to fight its way into a position to launch ordnance against the planet, and greater chance that nuclear weapons will hit and be effective.
Except by this time, it would be easier to tailor a virus that could kill not just planets, but whole subsectors with much less effort than a bunch of kinetic kill weapons. However, this runs against reality, such as today, where genocide, and genocidal weapons of mass destruction, simply aren't used. Functional NBC warfare was developed during WW2, but for the most part, except for cases like http://en.wikipedia.org/wiki/Unit_731 or the bombing of Nagasaki and Hiroshima, it never becomes standard procedure.
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