Where I find my inspiration

[PFVA63]

2LS is the mil sensor range in CT.

Most military craft in MT, TNE, T4, and T20 have multiple light-day sensor ranges.

They'd be detected well before, as that's a week of burn, and a single freighter of rubble ends your attack run in gory detonations, and since that ends your acceleration, you miss the world, too.

Hi,

In general, my thoughts on such an attack, fall kind of along the lines of some of the stuff discussed in the Anime Planetes, specifically the Kessler Syndrome where basically (in this case) if an enemy were to make a high speed pass, launching a couple missiles or whatever, that could detonate as they approach a planet, spraying a range of orbit bands with a lot of debris, this could potentially damage any satellites, ships or other items in orbit, creating a cascade of further damage through those orbit bands, disrupting surface to orbit transit, and potentially communications, navigation and other such things if enough satellites get damaged.

Similarly, it would be fairly easy for an attacker to know where the various Lagrange Points would be, and similarly they could make a high-speed pass launching similar "buckshot" filled missiles to spray these locations as well.

In general, a tactic like what you have described, using a freighter load of rubble, that could potentially be used against any ship, provided that you know where the enemy might transit. However, there are many potential possible short comings with trying to enact such a defense. First you'd have to anticipate such attacks and have the necessary equipment (freighters of rubble and such) located within range of each potential target planet/satellites.

Next you'd have to position you're "freighter" in a position to block the incoming enemy, which will be capable of maneuvering all the way in and which may actually be along several vectors, depending how many attacking ships there are. And finally, since the inbound enemy will likely be firing missiles that don't necessarily have to hit anything to be effective (they just need to spray part of the orbit above a planet, even if they are hit and or "exploded" before reaching the point where it would have normally detonated anyway, the debris of the missiles may still have the same effect (that of peppering a part of the orbit around the planet with debris).

In addition to the above as already suggested by others, any sensor that can detect out to light minutes, light hours, or more really only tells someone where you were that many minutes or hours ago.

 

[aramis]

PFVA, you're overlooking one MAJOR flaw in your logic... (aside from using Anime to justify anything)...

The inbound force has a very limited range of potential target points - and their burn will give away which rather quickly. They are literally sitting ducks. They dodge and miss, or they accept engagement.

Anime runs by Rule of Cool - if it looks cool, it generally works.
Traveller isn't written for Rule of Cool - it does play a bit loose with certain elements of physics, but is generally fairly realistic. And that means from any given point in system, there's only one time-efficient course to any given target.

Plus, at speeds of up to 10PSL (a week at 6G), the dust in basically empty space is itself a radiation hazard, and not a small one. A BB encountered at those kinds of speeds is a potentially fatal encounter for even a cruiser. V of 36E6m/s is 1.3E15 Joules per kilogram, or about 0.3KT per gram. And each square meter is getting a significant fraction of a gram in dust.

The single high speed pass is a serious desperation move - a freighter and a gravel pit can be catastrophic. Hell, a freighter and a garbage dump.

There is no assymetry, either. The faster you're going, the less reaction time from detection of their launch you have. And a 60KG missile is a total-kill on even a large ship doing 0.5PSL+.

Such a high speed pass isn't a viable means of anything other than near-suicidal xenocide. (Something OS Card mentions in one of the later Enderverse novels...)

 

[PFVA63]

Hi,

I think that you might want to reread some of the stuff on the Kessler Syndrome. Its probably a lot harder science than anything in Traveller;

http://en.wikipedia.org/wiki/Kessler_syndrome
http://webpages.charter.net/dkessler/
http://apod.nasa.gov/apod/ap090218.html
http://lasp.colorado.edu/~lix/class/asen5335/hw6.html
http://www.nytimes.com/2007/02/06/science/space/06orbi.html?_r=0
http://www.wired.com/wired/archive/15.05/st_houston.html
http://www.wired.com/magazine/2010/05/ff_space_junk/
http://www.nytimes.com/2009/02/12/science/space/12satellite.html?_r=1&emc=eta1
http://spectregroup.wordpress.com/2008/03/24/earth-will-have-rings/

In addition to this, in orbital mechanics I believe that craft won't necessarily be travelling in straight lines but rather arcs and orbits which will vary with the acceleration burns of the craft.

In the end, when attacking, a track to a target doesn't necessarily have to be time efficient to the target either. If you can force the defenders to overcommit in one direction by approaching from multiple 3D vectors, with potential feints and break-offs I suspect that it may be very possible to disrupt a defensive forces disposition and look for the best opening for the first craft in.

A couple quick strikes like this could potentially disrupt one sides forces in a war and force increased defensive reaction in response.

In some ways this could be similar to how the German Asiatic Fleet in early WWI and the German Pocket Battleships and commerce raiders of WWII forced the Allies to commit forces to protect trade in theaters away from the front to counter these threats.

In addition, it also reminds me a bit of some stories that I've heard about WWII attacks on bomber formations where some defending fighters would only make a single high speed pass on the formation trying to cause as much disruption as possible and then breaking for home.

I don't think its a desperation move at all, but rather a means to try alternate tactics to try and act in a means that an enemy may not be expecting. If your ships are capable of high, long term acceleration, then there might be some benefit in trying to see if you can make use of that.

And finally, if an attacking force is accelerating in at a high-speed against a defending force that is initially at a fairly low initial acceleration and speed, then if the defender sits and waits for the attack, the relative difference of the vectors of the two forces will likely be great once they get close in, and if the defenders try instead to move toward the attackers the delta in vector will probably be even greater. As such I would have my doubts of any need to try and slow down to try and engage the defenders in any sort of more convectional battle.

 

[Carlobrand]

Hi,

I think that you might want to reread some of the stuff on the Kessler Syndrome. ...

The Kessler Syndrome describes the behavior of a very large amount of material in a vary large volume of space. I don't think your attackers can replicate that scale.

You have the basic problem that your "shot" are unguided and non-maneuvering. No matter how fast you go, they still need to cross the distance from you to him before his lateral boost can take him out of their path. Thus, you either take them in close yourself - and risk getting killed before you can release them - or you launch a very wide "net" from farther out. However, the wider your "net", the more mass you need to make it - and the individual masses can't be too small or a well-placed nuke will turn the ones threatening a given target into an expanding gas cloud far enough out that the target won't be too badly endangered.

A kilometer-radius net involves over three million square meters of area. If you expect a density of one impactor per hundred square meters, for example, that's 31,400 impactors times whatever they happen to weigh. Stretch it to ten kilometers radius, you need over three million impactors. Stretch it to a hundred, you need three hundred million - but a 6-g ship can cover a hundred kilometers in about a minute, so you still have to be less than a minute away before you have a chance of hitting him.

Unless you change Traveller maximum-g rules for ships or are very lucky with a jump, you will have to spend a week or more acquiring the velocity needed to do lethal damage, and - space being space, and depending on the rule set - he will spend much of that week seeing you do it. Trying to put him inside that lethal 1-minute cone when he's seeing you coming for the past week is going to be one really neat trick. He could:

- send something cheap and expendable up to do exactly the same thing to you, forcing you to either avoid it (and acquire so much lateral delta-v in the process that you end up missing the target) or release your payload far too early, when they have only a fraction of the necessary speed and are likely to spread far too thinly to have any hope of hitting you.

- set several nukes on the line between you and him, so that either you or your payload encounters a succession of nuclear blasts, vaporizing a tunnel in the inbound "net" just big enough for the ship to pass through.

-put the body of the planet - or just the local moon - between you and him, monitoring you indirectly by satellite.

And, the faster you're charging in, the less arc is involved. At the speeds you're considering, it might as well be a straight line.

 

[Timerover51]

Hi guys.

I'm new to the forum ... but not new to Traveller. Well, not to Classic LBB Traveller, anyway. I'm happy with that as a set of rules providing a framework for my Sci Fi RP gaming, so I have never felt the need to move on to other variants.

I'm sure this has probably been discussed many times before, but I thought I'd share a few of the ideas that have given me inspiration for the design of my Traveller universe.

Pardon me, but what does this extensive discussion of ship tactics have to do with the original post?

 

[Carlobrand]

Pardon me, but what does this extensive discussion of ship tactics have to do with the original post?

I think it comes under the heading of exploring the ramifications of 57th century technology on that Age-of-Sail paradigm.

 

[aramis]

I think it comes under the heading of exploring the ramifications of 57th century technology on that Age-of-Sail paradigm.

That and that "stay on topic" hasn't been enforced here in a decade, provided that it follows a natural flow of conversation drift. (It has been enforced in certain limited circumstances - mostly by pulling the spur off into a separate thread).

The implications of the age of sail model informing HG are that it's a very poor representation of what should happen.

 

[PFVA63]

The Kessler Syndrome describes the behavior of a very large amount of material in a vary large volume of space. I don't think your attackers can replicate that scale.

You have the basic problem that your "shot" are unguided and non-maneuvering. No matter how fast you go, they still need to cross the distance from you to him before his lateral boost can take him out of their path. Thus, you either take them in close yourself - and risk getting killed before you can release them - or you launch a very wide "net" from farther out. However, the wider your "net", the more mass you need to make it - and the individual masses can't be too small or a well-placed nuke will turn the ones threatening a given target into an expanding gas cloud far enough out that the target won't be too badly endangered.

A kilometer-radius net involves over three million square meters of area. If you expect a density of one impactor per hundred square meters, for example, that's 31,400 impactors times whatever they happen to weigh. Stretch it to ten kilometers radius, you need over three million impactors. Stretch it to a hundred, you need three hundred million - but a 6-g ship can cover a hundred kilometers in about a minute, so you still have to be less than a minute away before you have a chance of hitting him.

Unless you change Traveller maximum-g rules for ships or are very lucky with a jump, you will have to spend a week or more acquiring the velocity needed to do lethal damage, and - space being space, and depending on the rule set - he will spend much of that week seeing you do it. Trying to put him inside that lethal 1-minute cone when he's seeing you coming for the past week is going to be one really neat trick. He could:

- send something cheap and expendable up to do exactly the same thing to you, forcing you to either avoid it (and acquire so much lateral delta-v in the process that you end up missing the target) or release your payload far too early, when they have only a fraction of the necessary speed and are likely to spread far too thinly to have any hope of hitting you.

- set several nukes on the line between you and him, so that either you or your payload encounters a succession of nuclear blasts, vaporizing a tunnel in the inbound "net" just big enough for the ship to pass through.

-put the body of the planet - or just the local moon - between you and him, monitoring you indirectly by satellite.

And, the faster you're charging in, the less arc is involved. At the speeds you're considering, it might as well be a straight line.

Hi,

I'm a bit confused on where the assumption that the incoming missiles will be "non-guided" and non-maneuverable", as I had assume that they would be missiles firing fragmentary warheads. As such, prior to detonation the missiles will still be very maneuverable as well as guided. There is the potential that even if the missiles are destructed prior to planned detonation, that the debris from this destruction will also contiue on unguided and potentially serve the same purpose as if the warhead detonated though.

Beyond this, from what I've read a Kessler Syndrome type event will not necessarily require a large amount of material in a large volume of space. Here is a brief article discussing how a single 8 ton satellite currently in Earth orbit (as of the time the article was written this Auguast) and how it could potentially serve as a starting point "close" to what many believe would be suffient for a trigger to a Kessler Syndrome type event. The article goes on to note that this satellite currently passes within 200m of at least teo catalogued items in space every year.

http://www.spacesafetymagazine.com/2012/04/25/don-kessler-envisat-kessler-syndrome/

In addition to this, it is also worth noting that no specific limited area would have to be targeted, as a large amount of debris passing at high velocity through low Earth orbit briefly over say Siberia would likely have just as much a chance of impacting some orbiting satellites and/or other space debris altering their current trajectories just as much as if the same "cloud" were to instead pass through low Earth orbit over say Brazil, China, the Pacific Ocean or any other area. Or in other words, the attacker would only have to put some "debris" (be that ball bearings projected outward from a detonating warhead or the fragmentary remains of the exploded missile itself, etc) through some part of the volume around a planet where satellites, ships, and even space debris may already be orbiting. As such a defender would have to protect against many possbile trajectories where the incoming missiles may be able to detonate their warheads so that the debris from them will pass through a part of that volume.

If you consider that many missile firing ships may be inbound, each taking a slightly different vector, including considering that you are operating in a 3D environment, where an orbit slightly off the ecliptic plane (both above and below) can later re-intersct that plane both due to its manevering ability and the elliptical nature of orbits, you have a much more complex issue to deal with rather than just assuming all the enemy ships and/or missiles must pass through this "hex" on the map therefor I'll put a "roadblock" here (be that a barrier of nuclear detonations timed for best effect or a "freighter's worth of rubble").

For reference, here are a couple images showing the extent of current satellites, catalogued debris and other orbiting object currently around Earth to give some idea of what may be involved. A blast of high velocity "debris" through any small arc of space (especially in Low Earth Orbit) may well be sufficient to damage, deflect and/or break off enough components (or new debris) such that these new pieces of debris and damaged satellites and other orbiting objects would then begin to start impacting other itmes in orbit that were well clear of the initial "blast" of incoming debris.

From other comments here though, I see that although this initial discussion was spawned by some thoughts I got the "inspiration for" from watching a certain anime series, the overall discussion is kind of getting away from the OP, and as such should maybe be moved elsewhere if continued. One thing that this vearing off of the discussion has brought to my mind is, if I/you/whoever were respensible for laying out the defense of a Solar System like Earth in a Traveller like setting, how would I/you/he go about it. Maybe that would be a good start for a new/spearate discussion, perhaps in the "Fleet" subgroup of this board.

http://upload.wikimedia.org/wikipedia/commons/a/a1/Debris-GEO1280.jpg

http://webpages.charter.net/dkessler/files/Kessler Syndrome-AAS Paper.pdf

 

[Carlobrand]

Hi,

I'm a bit confused on where the assumption that the incoming missiles will be "non-guided" and non-maneuverable", as I had assume that they would be missiles firing fragmentary warheads. As such, prior to detonation the missiles will still be very maneuverable as well as guided. There is the potential that even if the missiles are destructed prior to planned detonation, that the debris from this destruction will also contiue on unguided and potentially serve the same purpose as if the warhead detonated though.

Beyond this, from what I've read a Kessler Syndrome type event will not necessarily require a large amount of material in a large volume of space. Here is a brief article discussing how a single 8 ton satellite currently in Earth orbit (as of the time the article was written this Auguast) and how it could potentially serve as a starting point "close" to what many believe would be suffient for a trigger to a Kessler Syndrome type event. The article goes on to note that this satellite currently passes within 200m of at least teo catalogued items in space every year.

http://www.spacesafetymagazine.com/2012/04/25/don-kessler-envisat-kessler-syndrome/

In addition to this, it is also worth noting that no specific limited area would have to be targeted, as a large amount of debris passing at high velocity through low Earth orbit briefly over say Siberia would likely have just as much a chance of impacting some orbiting satellites and/or other space debris altering their current trajectories just as much as if the same "cloud" were to instead pass through low Earth orbit over say Brazil, China, the Pacific Ocean or any other area. Or in other words, the attacker would only have to put some "debris" (be that ball bearings projected outward from a detonating warhead or the fragmentary remains of the exploded missile itself, etc) through some part of the volume around a planet where satellites, ships, and even space debris may already be orbiting. As such a defender would have to protect against many possbile trajectories where the incoming missiles may be able to detonate their warheads so that the debris from them will pass through a part of that volume.

If you consider that many missile firing ships may be inbound, each taking a slightly different vector, including considering that you are operating in a 3D environment, where an orbit slightly off the ecliptic plane (both above and below) can later re-intersct that plane both due to its manevering ability and the elliptical nature of orbits, you have a much more complex issue to deal with rather than just assuming all the enemy ships and/or missiles must pass through this "hex" on the map therefor I'll put a "roadblock" here (be that a barrier of nuclear detonations timed for best effect or a "freighter's worth of rubble").

For reference, here are a couple images showing the extent of current satellites, catalogued debris and other orbiting object currently around Earth to give some idea of what may be involved. A blast of high velocity "debris" through any small arc of space (especially in Low Earth Orbit) may well be sufficient to damage, deflect and/or break off enough components (or new debris) such that these new pieces of debris and damaged satellites and other orbiting objects would then begin to start impacting other itmes in orbit that were well clear of the initial "blast" of incoming debris.

From other comments here though, I see that although this initial discussion was spawned by some thoughts I got the "inspiration for" from watching a certain anime series, the overall discussion is kind of getting away from the OP, and as such should maybe be moved elsewhere if continued. One thing that this vearing off of the discussion has brought to my mind is, if I/you/whoever were respensible for laying out the defense of a Solar System like Earth in a Traveller like setting, how would I/you/he go about it. Maybe that would be a good start for a new/spearate discussion, perhaps in the "Fleet" subgroup of this board ...

If you wish to lead, I'll be glad to follow, but could you shrink the size of that big picture? It's blowing the page formatting to heck.

I really don't think you're fully appreciating the scale involved. I see your image - hundreds of dots clustered around the Earth. However, the Earth is 8000 miles wide. Those white dots represent satellites whose measures are taken in yards. A better way to look at it is imagining that world globe filling your room, then imagining each of those dots being the point of a needle. What you're trying to do is very much like trying to kill a swarm of gnats with a shotgun loaded with birdshot - you might hit one or two, but you aren't going to accomplish much overall.

The problem with the missile idea is they're more vulnerable. You're still in the position of either coming in close to make sure they get through or firing from standoff - and seeing them rendered inert by outbound defenses. An outbound missile casting a cloud of sand in their path, or a few nukes set as mines between your missiles and their target, is enough to convert them from guided missiles to inert hypervelocity masses.

The enemy doesn't have to kill you to survive the battle - he only has to make sure you don't kill him long enough for you to sweep past, after which he can tail-chase you long enough to see if you're going to give it up and jump home or slow down and turn around. If you slow down, he can engage you in an old-fashioned slugfest.

 

[PFVA63]

If you wish to lead, I'll be glad to follow, but could you shrink the size of that big picture? It's blowing the page formatting to heck.

I really don't think you're fully appreciating the scale involved. I see your image - hundreds of dots clustered around the Earth. However, the Earth is 8000 miles wide. Those white dots represent satellites whose measures are taken in yards. A better way to look at it is imagining that world globe filling your room, then imagining each of those dots being the point of a needle. What you're trying to do is very much like trying to kill a swarm of gnats with a shotgun loaded with birdshot - you might hit one or two, but you aren't going to accomplish much overall.

The problem with the missile idea is they're more vulnerable. You're still in the position of either coming in close to make sure they get through or firing from standoff - and seeing them rendered inert by outbound defenses. An outbound missile casting a cloud of sand in their path, or a few nukes set as mines between your missiles and their target, is enough to convert them from guided missiles to inert hypervelocity masses.

The enemy doesn't have to kill you to survive the battle - he only has to make sure you don't kill him long enough for you to sweep past, after which he can tail-chase you long enough to see if you're going to give it up and jump home or slow down and turn around. If you slow down, he can engage you in an old-fashioned slugfest.

Hi,

Sorry about the image, I just linked to one off Wikipedia. I see that one of the Moderators appears to have cleaned up the issue for me (Thanks).

I think you hit on what I am trying to get at toward the end of your post.

Specifically " An outbound missile casting a cloud of sand in their path, or a few nukes set as mines between your missiles and their target, is enough to convert them from guided missiles to inert hypervelocity masses"

Which is perfectly fine for the purposes of what I am suggesting. Any mass of stuff moving through orbit at high velocity (even a bunch of destroyed missiles) will have the potential for intersecting orbit with anyone of numerous (hundred?, thousands?) orbiting objects. A collision with anyone of these orbiting objects (be they satellites, spacecraft, or space debris, etc). An impact with any of these items will create its own debris field in multiple new slightly different orbits (depending on angle of impact with the incoming object, the resultant tumbling and/or change in vector it may impart on the struck object and the failure modes off how the pieces may break off the struck object.

These new pieces of debris, in their new orbits may now begin impacting other orbiting objects causing for new debris fields in additional orbits.

This is why the Kessler Syndrome is termed a "cascading" event. A few initial collisions create additional debris that in turn cause further collisions, etc.

In a far future setting where planets may have orbiting power stations and other such things, a cascading event like this may be an even bigger issue than if such an event were to occur in modern times on Earth.

PS. Another thing to consider is that while each of the dots in the image of stuff currently orbiting Earth might be consider similar to a "pinhead" it should also be remembered that these are not static "pinheads" but rather they are in motion crisscrossing throughout this space.

 

[Carlobrand]

...
These new pieces of debris, in their new orbits may now begin impacting other orbiting objects causing for new debris fields in additional orbits.

This is why the Kessler Syndrome is termed a "cascading" event. A few initial collisions create additional debris that in turn cause further collisions, etc.
...

The Kessler Syndrome begins with the assumption of objects moving at orbital velocities - or at least at something much closer to orbital velocities than you are envisioning.

At the velocities you are envisioning, I see two types of "additional debris". The stuff that is going to be tossed out on a trajectory to intersect neighbors other than those on your vector, is going to be moving at something more like "normal" velocities; in a milieu that assumes Factor 40 armor as a minimum (Striker, MegaTraveller), neighboring craft and satellites will be able to resist that. Factor 40 armor is equivalent to a bit over a foot of steel - excessive, in many people's views, but it is canon from at least Striker forward, and that level of armor would stop a hypervelocity round from an 80mm tank gun. Compared to that, our modern satellites are basically glass-walled.

The stuff that's moving with something more akin to the extreme velocities you are envisioning, will also have something more akin to your trajectory. In other words: only targets more or less along your vector are at risk from that material. And, again, scale works against you - lot's and lots of open space, odds of a random intersection pretty low.

In a nutshell, the Traveller universe seems to have anticipated and addressed the potential for cascade events.

 

[PFVA63]

Hi,

I don’t agree with your assessments. The debris from an exploding or destroyed missile may be on a very small scale (think for example of a missile with a warhead filled with “buckshot”, “birdshot”, “BB’s”, or “ball bearings”, for example). With regards to armoring, I would suspect that it would be very hard to armor Solar Panels, antennae, and the like, let alone many other components of many satellites or other space debris.

As for number of incoming missiles, I took a look at Mongoose’s High Guard last night and noted that the typical cruiser that they should has a capacity of 6000 missiles. Since the distance between say Mars to Earth, or the Asteroid Belt to Mars, or Saturn to Jupiter, etc may be measured in days, if not weeks at a 4G acceleration this would seem to give the attacker ample time to pump out these missiles, even if you delay the first launch a few days, in order for the firing ship to have reached a relatively fast velocity. Also, there is no reason for the attacker to take a direct course towards Earth, but rather they may be using part of their maneuver to adjust trajectory a bit, so that some missiles may be targeting passing through orbit in the northern hemisphere while others pass through orbit in the southern hemisphere, with some at lower latitudes and others at higher ones, etc.

Due to the different firing times of these missiles (based on the ever increasing then possibly decreasing velocity of the attacking ship(s)) their arrival will likely be quite staggered, and then if you consider that rather than just one single attacking cruiser you may have several more ships in the attacking flotilla, then I think you can see just how complex the situation may become.

For example just half a dozen cruisers could potentially put 36,000 inbound, and if each ship is on a separate trajectory, maneuvering a bit to vary the directions for missiles fired one hour from the trajectory of the missiles fired in previous or future hours, then any thoughts of just blocking one “area” of space will likely be infeasible.

The explosion (or even destruction) of these 36,000 missiles (espcecially if fitted with special warheads of “buckshot” or its space warfare equivalent) all potentially streaking through orbit at varying times and latitudes would seem to me very likely to impact more than just a few existing orbital items, altering their existing orbits, creating new debris fields which then in turn will likely cascade on further and further.

As such, orbiting satellites such as those for comms, GPS-like services, and power generation, etc, plus any existing bits of debris, shuttles, grav vehicles, and other such items would likely also be at risk and eventually enough debris from the cascading events could likely make any transit through low Earth orbit by any vehicle not well shielded infeasible.

 

[Carlobrand]

Hi,

I don’t agree with your assessments. The debris from an exploding or destroyed missile may be on a very small scale (think for example of a missile with a warhead filled with “buckshot”, “birdshot”, “BB’s”, or “ball bearings”, for example). With regards to armoring, I would suspect that it would be very hard to armor Solar Panels, antennae, and the like, let alone many other components of many satellites or other space debris.

This has been going a bit now. I don't know how to prove this to you without getting into very detailed mathematics, and it's becoming clear from your answers that you haven't done the math on this yourself.

Let's do this. Let's put aside the odds of hitting the first target for the moment, and let's focus on that cascade you're thinking about. So, first question: assuming the launching ship managed 6G for a week before launching whatever munition he's launching, how much energy does, say, a 1 kg impactor carry?

How does a 1 kg impactor travelling at 18 thousand klicks per second actually interact with Target A? Does the target shatter like a bomb in all directions? Vaporize completely? Does the mass punch through like a bullet, yielding a conical spray of fragments from the "exit wound"? Or are the impact energies high enough that the mass under the point of impact would be vaporized, the impactor becoming a dense hot plasma that drills through like a fusion torch, yielding only vapor from the "exit wound"? The real point here is to study the physics of the interaction and figure out what if any fragments would be travelling in what directions, and whether they'd carry away anything remotely like the speed the impactor brought in.

Next: assuming B is a roughly cubish satellite of, say, 2dTons (27 cubic meters), and assuming for argument that target A explodes like a bomb when hit, throwing fragments in all directions, what are the odds of a random fragment from impact target A flying out 20 kilometers and hitting target B? How many such satellites would need to be within 20 km for Target A to have at least 50:50 odds of hitting one?

Assuming Striker's factor 40 armor, let's say it takes roughly a 1 kg mass travelling at 1500 m/s to penetrate. How much energy does that represent? Assume for the moment that Target A breaks up in an ideal manner, spreading enough fragments out to give that 50:50 chance of hitting one of the 2 dTon satellites out at 20km: how much energy is that? Is it reasonable for the impactor to deliver that energy to Target A, or is the impactor more likely to transfer only a portion of its energy and carry away the rest with it when it exits Target A?

Given the odds calculated above, what are the odds of hitting a specific piece of target B, say a vulnerable antenna of 1 square meter cross section - and why doesn't target B have a backup antenna?

What happens to a far future solar panel when a "ball bearing" passes through it? Is it rendered inert, or does it simply sustain a hole and continue operating at reduced power?

My concern is that me laying out the math and physics for you is only going to result in you doubting the math and finding reasons to maintain your view of what might happen. I really don't think you're grasping the scale or the nature of the interactions involved, and it's very clear that I'm failing to communicate those points, for which I blame no one but myself. I think it would be better if you analyzed the physics of the problem for yourself. Run some numbers - it doesn't have to be perfect, a lot of this is very rough approximations - and if you like the results then you can start up a new post and we can debate the physics, instead of turning this thread into a physics class.

As for number of incoming missiles, I took a look at Mongoose’s High Guard last night and noted that the typical cruiser that they should has a capacity of 6000 missiles. Since the distance between say Mars to Earth, or the Asteroid Belt to Mars, or Saturn to Jupiter, etc may be measured in days, if not weeks at a 4G acceleration this would seem to give the attacker ample time to pump out these missiles, even if you delay the first launch a few days, in order for the firing ship to have reached a relatively fast velocity. Also, there is no reason for the attacker to take a direct course towards Earth, but rather they may be using part of their maneuver to adjust trajectory a bit, so that some missiles may be targeting passing through orbit in the northern hemisphere while others pass through orbit in the southern hemisphere, with some at lower latitudes and others at higher ones, etc.

Due to the different firing times of these missiles (based on the ever increasing then possibly decreasing velocity of the attacking ship(s)) their arrival will likely be quite staggered, and then if you consider that rather than just one single attacking cruiser you may have several more ships in the attacking flotilla, then I think you can see just how complex the situation may become.

For example just half a dozen cruisers could potentially put 36,000 inbound, and if each ship is on a separate trajectory, maneuvering a bit to vary the directions for missiles fired one hour from the trajectory of the missiles fired in previous or future hours, then any thoughts of just blocking one “area” of space will likely be infeasible.

The explosion (or even destruction) of these 36,000 missiles (espcecially if fitted with special warheads of “buckshot” or its space warfare equivalent) all potentially streaking through orbit at varying times and latitudes would seem to me very likely to impact more than just a few existing orbital items, altering their existing orbits, creating new debris fields which then in turn will likely cascade on further and further.

Okay, let's do the math on 36 thousand buckshot missiles and see what the actual odds of hitting anything are when they're trying to hit objects that have a 10-30 square meter cross sectional area spread through a 150-some million square kilometer cross-sectional target area. How many such satellites need to be in that area for, say, 360 million 1.5 gram pellets to have a 50:50 shot at hitting at least one?

And, keeping in mind that this is a Traveller forum and that what we're discussing is paradigms for Traveller combat, let's add to that new post and talk a bit about your basis in Traveller for deciding that a ship can launch 6000 missiles over a period of time and have them all be able to select and home on targets several hours or days away - and how you intend to prevent the target from detecting and responding to them while they're still some minutes or even hours away.

I recall something like that strategy from Star Fleet Battles, but I'm not sure Traveller supports it.

 

[aramis]

Okay, let's do the math on 36 thousand buckshot missiles and see what the actual odds of hitting anything are when they're trying to hit objects that have a 10-30 square meter cross sectional area spread through a 150-some million square kilometer cross-sectional target area. How many such satellites need to be in that area for, say, 360 million 1.5 gram pellets to have a 50:50 shot at hitting at least one?

And, keeping in mind that this is a Traveller forum and that what we're discussing is paradigms for Traveller combat, let's add to that new post and talk a bit about your basis in Traveller for deciding that a ship can launch 6000 missiles over a period of time and have them all be able to select and home on targets several hours or days away - and how you intend to prevent the target from detecting and responding to them while they're still some minutes or even hours away.

I recall something like that strategy from Star Fleet Battles, but I'm not sure Traveller supports it.

Assuming a roughly even distribution of 36K "00" buckshot pellets (which really are about 3.5g spheres, 1cm or so across). A typical smallest-face cross section of a merchantman is 6x15m; of a warship, more like 30x30m or so. So, to assure a hit on a warship, we need to get 1 per 900m². 36K x900=32.4M m² - your "window" is 6.4km wide. Too small. Oh, and that's a 125kg bag of shot. Plenty fine for a heavy missile... but about 10x the payload of a "standard" CT missile.

So, we instead use a dumpster-load (about 2x1.5x1.5m) of about 18 tons... about 5 million pellets. Which gives about a 75.7km diameter sphere - which, for orbital insertion, is a fairly small window. double it to 150km, and your chance of hit drops from ~1 to about 0.25... versus a 5000Td destroyer. Vs a much bigger cruiser, that same pattern.

Going up to a 4 displacement ton standard shipping container, that's 6 dumpster-loads... and about 2.4x the radius. about 180km across. Double that (for a 25% chance vs a destroyer, or about a 150% chance vs a cruiser), and you've got a window about the minimum to assure an intercept.

Take that to a 100 ton freighter load... and you're getting 1800km across for assured hit on a DD, or 3600km for an assured hit on a CA.

Truth is, the shot will almost always be either edge biased or center biased, not evenly distributed. But that complicates the calculations more than I care to solve for. I'll stick to a 1st order approximation.

Still, I'd lay odds that the standard defense will be some discretionary burn missiles intended for intercept at distance. And if you acquire a planetary intercept vector that's not going to be orbital insertion, they will look for an intercept and shoot at you... because they've got nothing much to lose by shooting you, and a lot to lose if you decide your ship is the impactor.

 

[PFVA63]

Hi,

I suspect that there may be a fair bit of misunderstandings going on here between us. When I used the term “buckshot” I intentionally put it is quotes and also added reference to “or its space warfare equivalent” because this could really be anything that future scientists, strategists, and/or tacticians may figure makes sense. For example, looking at various proposals for anti-satellite missiles there have been a range of options including an expanding frame from a 1980’2 program called the Homing Overlay Experiment to the high-velocity, teardrop-shaped projectiles made of tungsten as kinetic warheads proposed for the proposed Brilliant Pebbles satellite based interceptors from later in the 1980’s.

http://en.wikipedia.org/wiki/Strategic_Defense_Initiative

For the sake of discussions let’s say that we have a 50kg missile whose warhead payload is about 1/5th that. If this 10kgs of payload is then detonated into 100 smaller subparts, instead of 36,000 inboard projectiles you would have at least 3.6 million (not considering the additional fragments of the missile bodies themselves which would also be continuing in on the final trajectory that the missile was following, and each of these submunition/parts would have a mass of about 1/100th of the 10kg payload (or 0.1kg – which is equal to about 0.22lb or 3.5oz – if I did the math right). This in turn is about equal to 2/3rds the mass of a standard baseball for reference.

With the respect to a satellite or other orbiting object, it might be worthwhile to consider what this actually means. As I understand it, in space any object in orbit is really in freefall about that object. And, for the most part the two main issues affecting/allowing this are that the object being orbited is exerting a gravitational pull on the orbiting object, and the orbiting object has a velocity which allows it to continue freefalling around the object being orbited.

Because the orbiting object is in space though, any contact with another object can/will impact that existing velocity vector that the orbiting object is moving along. In particular, in the simplest case, a hyper-velocity mass, even if it doesn’t penetrate the surface of what it impacts, will alter the velocity vector of that orbiting object. If the vector of the orbiting object and the impactor are in a relatively similar direction, the overall velocity of the orbiting object will likely increase, leading the orbiting object to either change into a higher orbit or actually leave orbit if the resultant new velocity vector of the orbiting object is greater than escape velocity.

If however, the impactor’s vector and the vector of the orbiting object are in different enough directions the resultant vector of the orbiting object will likely decrease, causing the orbiting object to begin to fall from its present orbit, if I am understanding correctly, and it may in fact eventually fall completely out of orbit, if the delta is great enough.

Because the impacted (orbiting) object is now on a new trajectory or orbit the possibility that the orbiting object (on this new likely unexpected trajectory) may impact other orbiting objects greatly increases, leading to further cascading events. Added to this is of course the potential that these 3.6 million inbound impactors may end up striking more than just one single orbiting object.

However, in addition to this, there are many other potential other things that may also occur. For instance, taking the 2dton satellite mentioned in a previous post, if an impactor strikes its surface same distance from the center of mass of the orbiting object, in addition to altering its vector it will also likely take on a spin or tumble. As such, even if this orbiting object were a “satellite” which could potentially be controlled from the ground, attempts to regain control may be very difficult due to this spinning and tumbling.

Depending on the construction of the satellite, including whether it has any attached solar panels and/or extended antenna, this spinning and tumbling could lead to those objects breaking free as well.

Other things to consider include that if the impactors do in fact penetrate the surface of an orbiting object there are many of the issues that have been mentioned previously. Specifically, systems can be destroyed on the orbiting object, the object could potentially be broken/torn/blown to pieces *due to this) and/or spalling and or plasma etc can be ejected, causing the formation of new pieces of space debris further increasing the chances of later cascading collisions with other objects. Specifically it is my understanding that any plasma formed by means of a collision will, in the emptiness of space, eventually change phase back into a solid forming new debris as well.

 

[aramis]

PFVA - the chances of a sub 10cm object hitting even a 4m² object, assuming a billion of them in near-identical orbits is still rather close to nil.

The Shuttle program has been hit by only a dozen or so items of any note - in 60+ flights - and has shown no propensity for hit objects to hit other objects other than the Earth. Anything in orbit that's hit either falls into a new orbit, is ejected from orbit, or falls into the object orbited, depending upon angle, altitude and velocity.... and we TRACK 10K+ objects in orbit.

The odds of hitting anything you aren't specifically aiming for is so low outside immediate orbital space as to be negligible.

If it's further out than Geostationary Orbit, tidal force will eventually clear it. Bigger items take longer to clear. Anything inside Geostationary will eventually be slowed down by tidal force and fall in.

Thing is, an orbital insertion window is pretty narrow - I can fling active terminal guidance missiles out to where the can intercept, and shoot you with their shot while you're slowing down to enter.

It's pretty damned easy to spot and track a ship. People were able to track the Apollo program capsules (10m x 4m) at 1LS with 10x binoculars, at least when the lit side was towards them.

 

[PFVA63]

Hi,

Here is some additional info for consideration.

From this Australian Government site on the Leonid Meteor showers (http://www.ips.gov.au/Educational/4/1/5 ) it notes that:

“In the extreme case, a large Leonid meteoroid could impact a satellite and cause sufficient damage so as to render the craft unusable. During the early days of space travel, the meteoroid hazard in general was considered a significant threat and NASA spent a considerable amount of money in trying to define the hazard nature and extent. Fortunately, the threat proved to be a lot less worrisome than first thought, although for large structures, such as the International Space Station (ISS), which will orbit for lengthy periods, the meteoroid threat does become significant, and shielding against this threat will be carried by the ISS.

If a Leonid storm rate of 100,000 per hour does eventuate, several predictions have been made that at least one if not several geosynchronous and/or low Earth orbiting satellites may be rendered inoperational. It has also been pointed out the debris hazard at the Earth-Sun Lagrange point (normally known as the L1 point) may be even more intense than on the Earth. This area is host to a number of scientifc satellites that observe the Sun and measure parameters of the space environment. If any of these were to be destroyed, we would lose a substantial space weather predictive ability which we have only recently attained.”

As it has been noted previously, just six cruisers could launch over 36,000 missiles which in turn could then fragment into 3.6 million separate 0.1kg “impactors”. (And of course a larger fleet would increase this to an even greater amount).

Additionally, here is another link to another article that provides some info on the spatial density of objects currently in Earth orbit, and another general article on space debris.

(http://www.google.com/url?sa=t&rct=...80q1BenYRIMnqmhI13j2Q&bvm=bv.1355534169,d.b2I)

(http://en.wikipedia.org/wiki/Space_debris)

One interesting thing to note is that the second article it notes that:

“In 1991 Kessler published a new work using the best data then available. In "Collisional cascading: The limits of population growth in low earth orbit" he mentioned the USAF's conclusions about the creation of debris. Although the vast majority of debris objects by number was lightweight, like paint flecks, the majority of the mass was in heavier debris, about 1 kg (2.2 lb) or heavier. This sort of mass would be enough to destroy any spacecraft on impact, creating more objects in the critical mass area. As N-sthe National Academy of Sciences put it:

‘A 1-kg object impacting at 10 km/s, for example, is probably capable of catastrophically breaking up a 1,000-kg spacecraft if it strikes a high-density element in the spacecraft. In such a breakup, numerous fragments larger than 1 kg would be created.’“

For reference, from this site (http://www.ajdesigner.com/constantacceleration/cavelocity.php) a ship accelerating at a constant 4G’s for a 7 day period would have achieved a velocity of 24,192,000 m/s (or 24,192 km/s) assuming an initial velocity of 0 m/s. As such a 0.1kg impactor would thus have 2,419,200 kg-m/s or N-s (or about 242 times the momentum of the 1kgm 10km/s object noted from the quote a few paragraphs ago that was suggested to be capable of destroying a spacecraft if it hits a high-density element).

Here is a listing of several large satellites and such that provide mass data for some Earth orbiting satellites (spaceflight.nasa.gov/shuttle/reference/green/sumcarg.pdf) showing some units up to maybe 40,000lb (or about 18mt).

This site also gives info on orbital velocities for Low Earth Orbit noting that “The speed needed to achieve a stable low earth orbit is about 7.8 km/s, but reduces with increased orbital altitude”.

(http://en.wikipedia.org/wiki/Low_Earth_orbit)

As such the momentum for am 18mt satellite in LEO may be somewhere on the order of about 140,400,000 N-s (if I did the calcs right). If anyone wants they can try and do some additional calcs to try and make some estimates of what a collision between these two items might result in.

PS. I also meant to note that according to this article (http://en.wikipedia.org/wiki/Space_debris) while "The Joint Space Operations Center, part of United States Strategic Command (formerly the United States Space Command), currently tracks more than 8,500 objects larger than 10 cm in LEO, however a limited Arecibo Observatory study suggested there could be approximately one million objects larger than 2 millimeters, which are too small to be visible from Earth."

 

[Carlobrand]

Sigh

Hi,

Here is some additional info for consideration.

From this Australian Government site on the Leonid Meteor showers (http://www.ips.gov.au/Educational/4/1/5 ) it notes that:

“In the extreme case, a large Leonid meteoroid could impact a satellite and cause sufficient damage so as to render the craft unusable. During the early days of space travel, the meteoroid hazard in general was considered a significant threat and NASA spent a considerable amount of money in trying to define the hazard nature and extent. Fortunately, the threat proved to be a lot less worrisome than first thought, although for large structures, such as the International Space Station (ISS), which will orbit for lengthy periods, the meteoroid threat does become significant, and shielding against this threat will be carried by the ISS.

If a Leonid storm rate of 100,000 per hour does eventuate, several predictions have been made that at least one if not several geosynchronous and/or low Earth orbiting satellites may be rendered inoperational. It has also been pointed out the debris hazard at the Earth-Sun Lagrange point (normally known as the L1 point) may be even more intense than on the Earth. This area is host to a number of scientifc satellites that observe the Sun and measure parameters of the space environment. If any of these were to be destroyed, we would lose a substantial space weather predictive ability which we have only recently attained.”

This is all very interesting, but it isn't Traveller. The Traveller orbiter's built like a tank - literally.

As it has been noted previously, just six cruisers could launch over 36,000 missiles which in turn could then fragment into 3.6 million separate 0.1kg “impactors”. (And of course a larger fleet would increase this to an even greater amount).

And Aramis pointed out that up to 5 million impactors gave you just a 1 in 4 chance of hitting something as big as a 5000 dT destroyer in a 150 km radius region. And you propose to spread over a larger area and try to hit smaller targets.

Additionally, here is another link to another article that provides some info on the spatial density of objects currently in Earth orbit, and another general article on space debris.

(http://www.google.com/url?sa=t&rct=...80q1BenYRIMnqmhI13j2Q&bvm=bv.1355534169,d.b2I)

Which tells us that the highest object density, at 1000 km altitude, for this world of - I believe it was 5.4 billion people as of the date of publication - is 1.5x10^-8 objects per cubic kilometer, or roughly 1 object per 60 million cubic kilometers. In other words, there's one satellite in a volume of space roughly 400 kilometers on a side

Just as an FYI: of the 439 systems of the Spinward Marches, there are only 42 with populations in the billions or greater. Nine times out of ten, you will encounter systems with much less in the way of orbital bric-a-brac - usually orders of magnitude less.

(http://en.wikipedia.org/wiki/Space_debris)

One interesting thing to note is that the second article it notes that:

“In 1991 Kessler published a new work using the best data then available. In "Collisional cascading: The limits of population growth in low earth orbit" he mentioned the USAF's conclusions about the creation of debris. Although the vast majority of debris objects by number was lightweight, like paint flecks, the majority of the mass was in heavier debris, about 1 kg (2.2 lb) or heavier. This sort of mass would be enough to destroy any spacecraft on impact, creating more objects in the critical mass area. As N-sthe National Academy of Sciences put it:

‘A 1-kg object impacting at 10 km/s, for example, is probably capable of catastrophically breaking up a 1,000-kg spacecraft if it strikes a high-density element in the spacecraft. In such a breakup, numerous fragments larger than 1 kg would be created.’“

Once more, the Traveller spacecraft's built like a tank. Not to say such a projectile wouldn't punch through rather easily, but it's behavior's likely to be more like a hypervelocity round punching through the tank - in other words, it's liable to punch a hole straight through rather than causing a catastrophic breakup.

For reference, from this site (http://www.ajdesigner.com/constantacceleration/cavelocity.php) a ship accelerating at a constant 4G’s for a 7 day period would have achieved a velocity of 24,192,000 m/s (or 24,192 km/s) assuming an initial velocity of 0 m/s. As such a 0.1kg impactor would thus have 2,419,200 kg-m/s or N-s (or about 242 times the momentum of the 1kgm 10km/s object noted from the quote a few paragraphs ago that was suggested to be capable of destroying a spacecraft if it hits a high-density element).
).

Very nice, but the question wasn't whether it would hurt the spacecraft. There's no doubt that an impactor doing 24 thousand klicks per second is going to pack a lot of punch. The questions are:

1) what are the odds of your impactor actually hitting something, and
2) if it hits, will it cause the target to shatter in a manner that throws additional shrapnel of lethal velocity about, or will it punch through and out the other side, leaving the target with a hole but otherwise intact, and
3) if the target shatters, what are the odds of a fragment hitting a neighbor with lethal force.?

Here is a listing of several large satellites and such that provide mass data for some Earth orbiting satellites (spaceflight.nasa.gov/shuttle/reference/green/sumcarg.pdf) showing some units up to maybe 40,000lb (or about 18mt). ...

Roughly 1 1/3 dTon volume.

This is a math exercise. If you don't do the math, you won't get the right answer. Your odds of hitting one 1 1/3 dT satellite in a volume of space 400 klicks on a side are around 1 in 557 billion. You propose to throw 3.6 million projectiles into the task - your odds are now something like 2 in 300,000.

 

[aramis]

For comparison - building disposable or single-use spacecraft in MegaTraveller requires AV4 for one-way, or AV8 for single trip ships. It requires AV 40 for normal ships. AV 4 is the equivalent of 1cm of steel, 8 is the equivalent of 2cm... AV 40 is the equivalent of 33cm of steel.

Quite a LARGE difference. And real apollo craft had the equivalent of 3-5mm of steel... much of which was actually foam.

 

[Fritz_Brown]

Such fragile things in which to traverse that immense gulf to Luna. Yet, we ventured forth to conquer the unknown. Amazing.

Merry Christmas, y'all.