Laser changes and the tactical use of missles

[BP]

...As noted maybe ships don't operate at high velocities, ...

Irregardless, interstellar objects do!

If one choose to not ignore the issue, whether a highport or a ship - all will need protection from high kinetic energy impacts and regardless of the protection will still be playing odds, like everything else unless one resorts to shields/magic. So, your premise still is valid...

 

[Mongoose Pete]

According to the Demolitions Table on Page 103 of the same supplement just 6 kilogram of conventional explosive of TL 9 are sufficient to penetrate Armour Value 40 enough to break its sealed environment integrity. If the energy of 6 kg of explosive are enough to penetrate the armour, its protection against the kinetic energy of micro-meteoroids is truly negligible.

Say we take Octaazacubane, a currently theoretical explosive suitable for TL9, at 22.9 MJ/kg (in comparison to TNT at 4.6 MJ/kg) then you are still looking at a not insignificant puncture energy of 137 MJ. Not bad for the basic hull of what I'd consider to be the equivalent of an unarmoured starship in MgT.

So (taking that explosive and the premise raised in MT) basic hulls should be able to weather sand particles at 51 km/s. In fact they could survive impacts of up to several kg at that velocity. More if we start plating them with armour.

Irregardless, interstellar objects do! Wink

If one choose to not ignore the issue, whether a highport or a ship - all will need protection from high kinetic energy impacts and regardless of the protection will still be playing odds, like everything else unless one resorts to shields/magic. So, your premise still is valid...

I honestly don't think folks need to rely on shields/magic. As I wrote before, I'm pretty sure pebble sized objects can easily be detected far enough away in order to avoid a collision - assuming your sensors are working and the M-drive isn't cold (passive observation of 2.5cm objects at a nearly a thousand klicks is achievable now). Smaller stuff should bounce off the armour, and wedge shaped deflection surfaces probably help too.

Also as others pointed out, there's a lot of volume out there, and not very much material filling it. I can visualise most incidental interceptions being automatically avoided by the autopilot, without passengers even noticing the tiny changes in velocity required to slip past them.

After all, how many deep space robotic missions have we sent across our solar system which have exploded dramatically from a micro-meteorite encounter? And there must have been several centuries worth of flight time logged between them.

So unless you purposely travel through a known cometary orbit, or the pilot has a severe case of lead-foot and tears through systems at high hundreds or thousands of km/s I don't think its that big a problem.

I could be wrong of course! But at the moment I've not seen any astronomical data suggesting its that bad out there, as long as you keep your sensors peeled and fly carefully. :wink:

 

[rust]

Say we take Octaazacubane, a currently theoretical explosive suitable for TL9, at 22.9 MJ/kg (in comparison to TNT at 4.6 MJ/kg) then you are still looking at a not insignificant puncture energy of 137 MJ. Not bad for the basic hull of what I'd consider to be the equivalent of an unarmoured starship in MgT.

I think you are a bit generous with the efficiency of the TL 9 explosive.

According to the table mentioned, the 6 kg of TL 9 explosive are the equi-
valent of 12 kg of TL 5 explosive, which is most probably TNT, and so we
are talking about ca. 55 MJ instead of 137 MJ.

Anyway, as mentioned before, I would just ignore this "problem" of hits
by fast small particles. In my view it is a rather hypothetical danger in
the real world and an unnecessary complication in the game.

 

[srogerscat]

I agree with Rust. Sensors spot them, and they are either dodged or zapped.

 

[DFW]

If the energy of 6 kg of explosive are enough to penetrate the armour, its protection against the kinetic energy of micro-meteoroids is truly negligible.

Well, I never said the game designer possessed the science knowledge of an 8th grader.

 

[BP]

...Say we take Octaazacubane, a currently theoretical explosive suitable for TL9, at 22.9 MJ/kg (in comparison to TNT at 4.6 MJ/kg) then you are still looking at a not insignificant puncture energy of 137 MJ. ...
So (taking that explosive and the premise raised in MT) basic hulls should be able to weather sand particles at 51 km/s. In fact they could survive impacts of up to several kg at that velocity. More if we start plating them with armour.

Don't neglect force per unit area - the penetrating force required for a needle vs a fist are quite different.

I'd agree with the sand particles being 'weatherable' (what I referred to in a previous post as ablative of surfaces over time), but think you might have missed some unit conversions when referring to 'several kg' impacts. Even at just 1 kg at 51 km/s, the KE is 0.5 x 1 kg x 51,000 m/s x 51,000 m/s or about 1300 MJ. So even 1 kg is 10 times more powerful than needed in the example above.

If one choose to not ignore the issue, whether a highport or a ship - all will need protection from high kinetic energy impacts and regardless of the protection will still be playing odds, like everything else unless one resorts to shields/magic. So, your premise still is valid...

I honestly don't think folks need to rely on shields/magic. As I wrote before, I'm pretty sure pebble sized objects can easily be detected far enough away in order to avoid a collision - assuming your sensors are working and the M-drive isn't cold (passive observation of 2.5cm objects at a nearly a thousand klicks is achievable now). Smaller stuff should bounce off the armour, and wedge shaped deflection surfaces probably help too.

A Highport is gonna avoid the strike?

My post was probably unclear. It is about playing odds. Given thousands and thousands of highports and many more moving ships - strikes are bound to happen. Again, unless one either ignores the issue completely - or resorts to handwavium technologies. So - no need to rely on such - rather, a need to accommodate the odds.

...
Also as others pointed out, there's a lot of volume out there, and not very much material filling it.

Yep - space is huge! Near stellar systems (if ours is anything to go by) are also full of stuff wizzing around...

In your example above (51 km/s) the ship has less than 20 seconds to move to safety and scan a volume of space over 4 billion, billion cubic meters of space for an object 1/400th of a meter in size. NASA actually factors on upto 80 km/s near Earth for micrometeorites - bringing that down to 12.5 seconds. Besides the potential to be moving even faster than that, small objects in space do occasionally travel with company.

...
I can visualise most incidental interceptions being automatically avoided by the autopilot, without passengers even noticing the tiny changes in velocity required to slip past them.

Me too.

...
After all, how many deep space robotic missions have we sent across our solar system which have exploded dramatically from a micro-meteorite encounter? And there must have been several centuries worth of flight time logged between them.

Actually, at least one has - but that was trailing a comet! (Not counting impactors there - one actually was lost from impacts at around the expected time and sized particles.)

All of our deep space probes have experienced small hypervelocity impacts - mostly harmless dust with the only real effect of reducing solar panel and comm array efficiencies, though a few were suspected as causes of minor system failures.

Irregardless, the volumes and surface areas of Traveller spacecraft and spacestations far, far exceed any relevance to today's space probes.

Past the orbit of Saturn, in the early '80s, Pioneer 10 and 11 found dust particles of unknown origin. Turns out the solar system appears to be surrounded by a ring of 'dust' possibly generated from object collissions in the Edgeworth-Kuiper belt. Of course, these are generally small and appear to have a density of only 1 ever 50 cubic km. Still, there is a lot of stuff zipping around in the solar system and sooner or later hardware will encounter it (the visible surface of the moon is an easy off scale reminder of that).

BTW, IIRC, the Long Duration Exposure Facility experiments (early '80s) recorded about 1,000 visible impacts per month (though that included manmade debris).

...
...astronomical data suggesting its that bad out there, as long as you keep your sensors peeled and fly carefully. :wink:

Even if you don't - the odds are with you (regardless of thrust...).

Likewise - given the 'age' and numbers in the OTU - the odds are very much in favor, even if extremely rare, of catastrophic occurrences.

Didn't see anyone really post otherwise - only that it was a potential issue that was not really addressed by most versions of Traveller. Even though, in RL, it is an issue space agencies evaluate, plan for and spend resources on without being a vast empire or equipped with 6G handwavium tech

Regarding Traveller - I play this as Referee determined 'random' RP fun as previously mentioned. If one were to try and make a mechanic, something rare and non-catastrophic would be appropriate.

 

[Mongoose Pete]

I think you are a bit generous with the efficiency of the TL 9 explosive.

According to the table mentioned, the 6 kg of TL 9 explosive are the equi-
valent of 12 kg of TL 5 explosive, which is most probably TNT, and so we
are talking about ca. 55 MJ instead of 137 MJ.

Opps. I didn't have the table to refer to, so I simply picked out a real world explosive currently being worked on. My mistake. :wink:

Anyway, as mentioned before, I would just ignore this "problem" of hits
by fast small particles. In my view it is a rather hypothetical danger in
the real world and an unnecessary complication in the game.

I agree.

 

[Mongoose Pete]

Don't neglect force per unit area - the penetrating force required for a needle vs a fist are quite different.

Very true. There are many configurations of micro-meteor material and shape which can affect the impact.

I'd agree with the sand particles being 'weatherable' (what I referred to in a previous post as ablative of surfaces over time), but think you might have missed some unit conversions when referring to 'several kg' impacts. Even at just 1 kg at 51 km/s, the KE is 0.5 x 1 kg x 51,000 m/s x 51,000 m/s or about 1300 MJ. So even 1 kg is 10 times more powerful than needed in the example above.

Apologies. I was writing at 2am and didn't have the mental clarity to check the math.

A Highport is gonna avoid the strike?

No. But the highport can probably mount better protection, much longer range sensors, and weapons capable of deflecting or breaking the object apart before impact. Its also more likely to be built in a system where dangerously sized material has been cleaned up. Otherwise yes, its technically a sitting duck and the locals wouldn't build one.

My post was probably unclear. It is about playing odds. Given thousands and thousands of highports and many more moving ships - strikes are bound to happen. Again, unless one either ignores the issue completely - or resorts to handwavium technologies. So - no need to rely on such - rather, a need to accommodate the odds.

Ah, I understand now.

In your example above (51 km/s) the ship has less than 20 seconds to move to safety and scan a volume of space over 4 billion, billion cubic meters of space for an object 1/400th of a meter in size. NASA actually factors on upto 80 km/s near Earth for micrometeorites - bringing that down to 12.5 seconds. Besides the potential to be moving even faster than that, small objects in space do occasionally travel with company.

Very true. My 51 km/s was the average cometary fragment speed, not its maximum, which could of course be in the thousands range for something ejected from an extra-solar black hole interaction.

As for coverage, then I'll fall back on the caveat of improving ship-board sensor tech, and the fact that civilised systems will likely emplace dozens of warning buoy sensors around their local area of operation (a few hundred diameters out from the homeworld at least) to pick up just such objects.

Concerning response time... Well at these velocities (assuming a small vessel) you only need to make a change of several metres per second to avoid the interception. With 12.5 seconds warning, a less than 1 second burst of acceleration/deceleration/or coasting from a Manoeuvre 1 drive would avoid the collision. (Unless my newly wakened brain is misfiring again :wink: )

That does assume of course, that the drives are already on-line and ready to respond - and its a single object, not travelling in company as you rightly pointed out.

...
After all, how many deep space robotic missions have we sent across our solar system which have exploded dramatically from a micro-meteorite encounter? And there must have been several centuries worth of flight time logged between them.

Actually, at least one has - but that was trailing a comet! (Not counting impactors there - one actually was lost from impacts at around the expected time and sized particles.)

Cool! I'll have to track details of that one down.

All of our deep space probes have experienced small hypervelocity impacts - mostly harmless dust with the only real effect of reducing solar panel and comm array efficiencies, though a few were suspected as causes of minor system failures.

Yes, so that sort of stuff can legitimately be ignored by traveller ships.

Irregardless, the volumes and surface areas of Traveller spacecraft and spacestations far, far exceed any relevance to today's space probes.

I'm sure that's a good reason for type s scouts to be wedged shaped, since they are likely to be exploring less well charted systems and probability increases that significant impacts will be frontal if you travel at higher speeds.

Past the orbit of Saturn, in the early '80s, Pioneer 10 and 11 found dust particles of unknown origin. Turns out the solar system appears to be surrounded by a ring of 'dust' possibly generated from object collissions in the Edgeworth-Kuiper belt. Of course, these are generally small and appear to have a density of only 1 ever 50 cubic km. Still, there is a lot of stuff zipping around in the solar system and sooner or later hardware will encounter it (the visible surface of the moon is an easy off scale reminder of that).

Likewise - given the 'age' and numbers in the OTU - the odds are very much in favor, even if extremely rare, of catastrophic occurrences.

Which for game fun suggests the inclusion of (non-catastrophic) impacts as in-system random events or the raison d'être of a scenario.

Didn't see anyone really post otherwise - only that it was a potential issue that was not really addressed by most versions of Traveller. Even though, in RL, it is an issue space agencies evaluate, plan for and spend resources on without being a vast empire or equipped with 6G handwavium tech

True!

 

[Captain Jonah]

Highports would have station keeping thrusters which would allow then to shuffle around a bit or they could be nudged by the many tugs in the area. A non mobile highport seems a bit odd when you have the capacity to build 1,000,000 dton starships, a bit 20th century

Scouts and many wedge and needle shaped ships will deflect many head on impacts. Something like a Far Trader on the other hand with that huge great glass house stuck on the front is in a world of hurt.

Something not mentioned, or I may have missed it, the object doing the hitting will also have an impact on how the starship armour resists it.
A chunk of low density ice hitting a slab of armour will flash vapourise itself disipating some of the impact energy. A sliver of bonded superdense blown of a warship in some old battle will go straight through a hull.

 

[rinku]

Scouts and many wedge and needle shaped ships will deflect many head on impacts.

Damme Cap, but if you haven't just put your finger on a flaw with spherical spaceships that's been bugging me. Needle/Wedge gets sloped armour vs oncoming hazards - spherical gets the least efficient armour protection

 

[rust]

... spherical gets the least efficient armour protection

I am not sure. The entire surface of a spherical ship is automatically "slo-
ped" to a certain degree, and a spherical armour shell also has the high-
est possible structural strength. Therefore it seems to me that a box sha-
pe would be a lot more vulnerable.

 

[DFW]

In your example above (51 km/s) the ship has less than 20 seconds to move to safety and scan a volume of space over 4 billion, billion cubic meters of space for an object 1/400th of a meter in size. NASA actually factors on upto 80 km/s near Earth for micrometeorites - bringing that down to 12.5 seconds. Besides the potential to be moving even faster than that, small objects in space do occasionally travel with company.

A 6G ship going from Earth to Jupiter is hitting top speeds ~9160 km/s. Too fast to detect & do anything about it, other than collide. Either that hull can handle ~41,952,800,000 joules or, say bye, bye. Especially, the bridge crew
hanging around the ships nose sitting behind glass. LOL

 

[DFW]

And I'm sure your own calculations of impact velocities would show that MT armour 40 is not sufficient of itself. There must still be something else at play to avoid the threats.

In reality, the only thing at play, is the sub par education of the writers...

 

[rust]

In reality, the only thing at play, is the sub par education of the writers...

Well, the writers obviously had a problem that had not much to do with
their level of education.

In order to write a science fiction game you can:

a) pay respect to scientific accuracy,
b) try to design plausible game mechanics,
c) try to make the game fun to play,

- but you can always only pick two of the three ...

 

[DFW]

Well, the writers obviously had a problem that had not much to do with their level of education.

I consider the inability to do basic math an education issue. In Sci-Fi you hand wave ONLY what you must. Jump drive, fusion power. You DON'T throw out VAST swaths of physics unless it makes the game/story impossible.
It wasn't necessary to throw out the entire subject of kinetic energy to make the game playable. Ergo, an EDU problem.

 

[rust]

I consider the inability to do basic math an education issue.

Consider the inability to apply basic physics such an education issue, too,
and FTL drives, gravitics and long range laser weapons go out of the win-
dow right behind the armour protection against fast particles - if you want
to have them in your science fiction games, you have to turn off the edu-
cated part of your brain. :lol:

 

[zero]

A 6G ship going from Earth to Jupiter is hitting top speeds ~9160 km/s. Too fast to detect & do anything about it, other than collide. Either that hull can handle ~41,952,800,000 joules or, say bye, bye. Especially, the bridge crew
hanging around the ships nose sitting behind glass. LOL

So what would be a sufficient level of armour for a 200 ton ship, also what if it was a Railgun (article on wikipedia for those not in the know) that would hit it?

Also, just wondering, if a system ship travels at a constant 3.3 AU per week (their top speed), how fast is that in km/s?

 

[rust]

Also, just wondering, if a system ship travels at a constant 3.3 AU per week (their top speed), how fast is that in km/s?

If I did not fumble my math roll, 3.3 AU per week should be about 816
kilometers per second.

So what would be a sufficient level of armour for a 200 ton ship ...

It would depend on the armour material and the size and speed of the im-
pacting object - and on your definition of "sufficient".
In the end, make the starship invulnerable to fast particles, and it is most
probably invulnerable to all non-military weapons, too, eliminating space
combat from most of the game.

 

[Mongoose Pete]

Well, the writers obviously had a problem that had not much to do with their level of education.

In order to write a science fiction game you can:

a) pay respect to scientific accuracy,
b) try to design plausible game mechanics,
c) try to make the game fun to play,

- but you can always only pick two of the three ...

There's a fourth option specifically concerning Traveller which is adherence to canon. But that's another issue altogether... :wink:

It wasn't necessary to throw out the entire subject of kinetic energy to make the game playable. Ergo, an EDU problem.

Well in MgT there are collisions. Micrometeorites and space junk appear on the Space Encounters table, and under the Collision entry it does state that 'Almost any collision at high speed will destroy even the most powerful spacecraft.' So Gareth did take things into account up to a point, and decided to leave out in-depth scientific accuracy in favour of simple mechanics and keeping it fun.

So don't belittle the man. He did a good job, aiming the game at being simple and fun, which has brought in a lot of old-timers and newer players. A re-release of Traveller at a FF&S level would not have come anywhere close to being as successful.

 

[Captain Jonah]

As Pete says above, Points B and C are the important ones to consider because the game must be fun and playable with a minimum level of math. If its no fun no one will play it anyway and if its too ”mathy” (hey I invented a new word ) you cut out a lot of people not happy with needing to take a calculator to a game.

Beyond a point, and not very far at that, the game play takes precedent. While in the real world impacts require some fairly thick armour layers to stop or deflect in game these quickly overwhelm the rest of the game system.

If micro meteorites can punch holes straight through armour 6 or armour 12 why are missiles so crap. After all a missile fired from maximum range is going to be moving at a fair clip when it hits and yet is just messes the paint work on small civilian ships most of the time. Not up to the speeds you could get but still fast enough to be noticed. Fit a missile with a warhead of kinetic penetrator heads and accelerate it from maximum range to the target and away it goes, or in MonT, doesn’t go.

To my mind there is a problem with combat and the lack of lethality with space weapons but until this gets Mongoose supplemented we can house rule while keeping it balanced. Using real physics to have a random encounter which basically goes “your ship is hit by a micro meteorite travelling at x kilometres per second, it punches through the hull and the energy release turns you into an expanding cloud of vapour” takes the fun out of things.

So for the sake of a good game it is far easier to leave physics at a fairly minimum level and just have fun. When a ship can withstand multiple hits from missiles and lasers with no more than minor damage then that is how the tough the ship’s hull is. In MonT star ship combat is not what you would call scary, oh no that enemy scout has a missile launcher, beam laser and sand caster. We are DOOOMED.

Playing TNE was fun in many ways but space combat was something to be afraid of, each incoming missile was something that could kill you. 8 or 10 missile hits in mongoose on a Free Trader may even breach the hull and put you in danger of getting hurt.

So space debris impacts need to be at the same level as other threats in order to hold a balance. Sadly physics takes second place, happily fun takes first place.