04-06-2003 15:40									#61
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quote: Originally posted by DRoseDARs Well, with the lasers the main idea I've heard is to use huge satelites to collect sunlight and focus it into a much tighter beam (microwaves I believe). This beam would then be directed at the business end of a modified solarsail. Think of it as going from a passive sail to a mud-bogger(?) (one of those boats with the big fan on the back). Would wouldn't rely on the gentle nudge of the sun to speed up to your target, instead you'd get a stronger shove from a concetrated beam. I forget what you'd do once you got to your target...

Ah I see. Still doesn't look very practical in space combat though.

Is it (theorethically) possible to make such efficient use of photons that you don't need huge sails?

	04-06-2003 15:41									#62
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quote: Originally posted by Colon Besides, anyone considered the danger of a "stray bullet" in space? On earth, when you're at a large distance from a battlefield, you're usually safe from stray bullets. (although missiles have increased the danger) But in space a stray bullet could hit a target lightyears away. I wouldn't want to know what happens if you start firing nukes in space. And what when you use missiles that accelerate? If such a missile goes astray it could end up hitting something (eg a planet) at enormous speed.

Someone mentioned an "auto-destruct" feature earlier. No way of ensuring everyone installed one on every missile (nuclear and otherwise), but its a very feasible option to prevent "stray-bullets."

Lasers would be more of a problem, though...

	04-06-2003 15:44									#63
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quote: Originally posted by DRoseDARs Someone mentioned an "auto-destruct" feature earlier. No way of ensuring everyone installed one on every missile (nuclear and otherwise), but its a very feasible option to prevent "stray-bullets." Lasers would be more of a problem, though...

Ok, I missed the auto-destruct post too.

But still, you're bound to have 'rogue-entities' (beit Nort Korea or otherwise ) that can't be bothered to use such auto-destruct features.

	04-06-2003 15:44									#64
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quote: Originally posted by Colon Ah I see. Still doesn't very practical in space combat though. Is it (theorethically) possible to make such efficient use of photons that you don't need huge sails?

Earlier this year there was a thread on one aspect of the US Anti-Ballistic missile shield: Airborne Lasers installed on 747s. I think a production model is due later this decade. Fully-functioning supposedly in the manner I've described, heating missiles to cause them to explode prematurely and with GPS to target the inbounds.

	04-06-2003 15:45									#65
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Stray bullets? The chance that some space missile or whatever will hit anything after missing it's target is nill.

	04-06-2003 15:47									#66
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quote: Originally posted by DRoseDARs EDIT: I was too slow in posting this. This post reponds to the one before the one above. Yeah, the first such probe was launched a few months back...maybe even back in 2001, I can't remeber specifics anymore. I think its primary mission was an asteroid/comet that passed near Earth. The Ion drive was just added to see if it would work. I believe it did quite well.

Actually I can vaguely recall that test. Looks more promising if you consider there's probably going to be a lot of improvement on that technology.

	04-06-2003 15:48									#67
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quote: Originally posted by DRoseDARs Earlier this year there was a thread on one aspect of the US Anti-Ballistic missile shield: Airborne Lasers installed on 747s. I think a production model is due later this decade. Fully-functioning supposedly in the manner I've described, heating missiles to cause them to explode prematurely and with GPS to target the inbounds.

Sure you're replying to the right quote?

	04-06-2003 15:49									#68
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quote: Originally posted by Eli Stray bullets? The chance that some space missile or whatever will hit anything after missing it's target is nill.

You are incorrect. Traditional missiles have targetted the wrong targets before. Operator error, screwed-up targeting systems, or simple aquiring a new target after losing contact with the original target.

Heat signatures and radar echoes are still used by missiles to track their targets.

	04-06-2003 15:50									#69
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quote: Originally posted by Colon Sure you're replying to the right quote?

Sorry, yes I was.

	04-06-2003 15:59									#70
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Well, I've hit 4am and I have things to do later today, so g'night all.

DRoseDARs

	04-06-2003 16:06									#71
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quote: Originally posted by DRoseDARs You are incorrect. Traditional missiles have targetted the wrong targets before. Operator error, screwed-up targeting systems, or simple aquiring a new target after losing contact with the original target. Heat signatures and radar echoes are still used by missiles to track their targets.

Space is big, and fuel / battery life is limited. I don't think that there is a serious safety issue here.

	04-06-2003 16:09									#72
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quote: Originally posted by Sikander Space is big, and fuel / battery life is limited. I don't think that there is a serious safety issue here.

But you don't need fuel to keep an object moving, only to make it accelerate. (whatever the means of propulsion is) And since it will keep moving, it is bound to hit something at some time.

	04-06-2003 17:29									#73
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Hi folks. Fascinating thread. For those who fancy trying some of these ideas, there's a family of games (old timers will know about it) called Elite and Frontier. The last version is called First Encounters and is available as shareware from the author (who won the copyright back in court. Ming, don't go cussing me).

Download PC versions here

You will also need JJFFE (or similar) to run Frontier First Encounters on Windows or Linux systems.


Get your JJFFEWIN OR Linux here

They are very compact games and run on the desktop. Elite 4 is under construction, supposedly with multiplay.

Happy shooting.

EDIT: Elite was heavily influenced by an OLDDDD RPG called Traveller - it's pre D&D, that's how old. Megatrav came out (late 80s?) with an updated ship design system that was even sillier. Honestly, a naval architect friend of mine couldn't believe the amount of errors in the rules.

Last edited by Cruddy on 04-06-2003 at 22:21

	04-06-2003 18:52									#74
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quote: Originally posted by Colon But you don't need fuel to keep an object moving, only to make it accelerate. (whatever the means of propulsion is) And since it will keep moving, it is bound to hit something at some time.

It depends. Consider this - if you fire a photon in a random direction, chances of it hitting something is much less than that of it moving to the "edge" of the universe. Pretty similar to that of a missile flying in a straight line.

	04-06-2003 18:59									#75
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quote: Originally posted by Urban Ranger It depends. Consider this - if you fire a photon in a random direction, chances of it hitting something is much less than that of it moving to the "edge" of the universe. Pretty similar to that of a missile flying in a straight line.

Guess so. At least Earth never got hit by stray bullets from some far away intergalactic battle.

	04-06-2003 19:03									#76
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Laser would be a good weapon for space battles. Moves at light speed, and the attenuation is much less out in space.

	04-06-2003 19:06									#77
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quote: Originally posted by MichaeltheGreat * This is easy to do with current technology. Just take CCD imagers with a given field of view, and constantly take a series of short exposure images. It's simple data processing to sum the values of all pixels in the CCD field, and compare that number to the number for previous exposures of the same area. If there's a difference, you have either a reflective object, or something passing in front of another object. Once you have a suspect field of view that has some activity in it, you can then focus other detectors on that area and try to get a visual/IR read on it.

The only problem with that is, when you finally detect something, it's no longer there.

But then, unless it moves relatively fast, probably somewhere at 0.1c at least, it's not that big a difference.

	04-06-2003 20:22									#78
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Battles aren't fought for the sake of having battles. Battles are fought to seize and protect objectives.

In the near future, the only objectives in outer space will be the satillites in orbit around Earth...and maybe a few space factories, labs and maybe missile platforms.

These objectives can all be attacked with relatively small, unmanned hunter-killer satillites.

Lasers won't be the weapons of choice; it's too easy to protect against them just by using mirrored surfaces. Rather, because all these orbitting objects travel at very high speeds, kinetic weapons will be used. Imagine the damage that would be done by a one-inch sphere of depleted uranium traveling at 20,000 mph. Or, for easy reloading, space junk can be chewed up and turned into flying schrapnel.

	04-06-2003 20:35									#79
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I am not an expert, but I don't think mirrored surfaces are that great a defense against laser beams. Light bounces of all sorts of surfaces, the only difference between a rough and a polished surface is how the photons bounce - in one direction or scattered around.

	04-06-2003 22:10									#80
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quote: Originally posted by Urban Ranger I am not an expert, but I don't think mirrored surfaces are that great a defense against laser beams. Light bounces of all sorts of surfaces, the only difference between a rough and a polished surface is how the photons bounce - in one direction or scattered around.

It really depends on the wavelength of the beam. It's just about impossible to shield against an X-ray laser.

I say just about because it is THEORETICALLY possible to dump a large mass of water or similar refracting material in front of the beam to break up the coherance - that is of course if you know or suspect one is on the way! You're talking about an AI taking an automatic reflex defense in response to a suspected threat, NOT a human pilot reaching for the ECM and chaff.

	04-06-2003 22:16									#81
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quote: Originally posted by Zkribbler Rather, because all these orbitting objects travel at very high speeds, kinetic weapons will be used. Imagine the damage that would be done by a one-inch sphere of depleted uranium traveling at 20,000 mph.

This is quite true, but the problem with kinetic weapons is that they are inherently "dumb". They won't make a course change if the target takes evasive action. It's also difficult to calculate the correct trajectory if the relative speed of firer and target is in the several KMs per second range.

It may seem impossible to detect such a small object at a meaningful distance, but even current battlefield artillery radar can detect small birds or even butterflies at a distance of several hundred metres. Not terribly useful when you're on the lookout for incoming mortar and LCG shells, but I hope you take my point.

	04-06-2003 22:27									#82
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Another problem with kinetic weapons is that they will indistinctively destroy anything they touch, ennemy satellites and vessels as well as yours. Their use in orbit should therefore be restricted to orbits around ennemy planets.

	04-06-2003 22:29									#83
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You could fire rocket from gun.
They will have to get througt anti missile defence. And forget on speeds. Big speeds big space will you hit? For example on 1 sec distance?

	04-06-2003 22:45									#84
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Regarding stealth spacecraft:

Whilst they may have a role to play, it will probably be limited for the following reasons :

Stealth coating is very expensive. The cost of the ship would rise by a huge amount, particularly if it had a high surface area design, like a needle or a disc.

Stealth coating requires a lot of maintainence to remain efficient, meaning that stealth ships will need a larger logistics train to operate effectively. On long missions, the stealth coating could become eroded by micro-meteorites, rendering it useless.

A stealthed ship will absord most incoming radiation in order to remain undetected. This will create problems with dispensing with heat. One solution would be internal refridgeration systems that can absorb a limited amount of heat, until they have to be expunged, this would be the equivalent of rigging for silent running. Another solution would be external radiators that can be deployed on the surface of the ship to dump excess heat on a continuous basis. For stealth ships, these could be directed away from probable areas of enemy observation.

Finally, a stealth ship would be very vulnerable to lasers.

	04-06-2003 23:16									#85
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I did a bit of thinking, and in a way space war is already here.

Both the US and Russia have deployed anti-sat missile systems. They can ONLY reach to low earth orbit though - say 100 miles orbit, which is way below what most milsats travel at.

IIRC, the US one was launched from a high flying F-15.

	05-06-2003 00:29									#86
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quote: Originally posted by Sandman Regarding stealth spacecraft: Whilst they may have a role to play, it will probably be limited for the following reasons : Stealth coating is very expensive. The cost of the ship would rise by a huge amount, particularly if it had a high surface area design, like a needle or a disc. Stealth coating requires a lot of maintainence to remain efficient, meaning that stealth ships will need a larger logistics train to operate effectively. On long missions, the stealth coating could become eroded by micro-meteorites, rendering it useless.

True, but stealth would give a force a huge first strike advantage. A ship with stealth features in both radar spectrum, visible spectrum, infrared spectrum, would be very difficult to detect. Such a ship could sneak in and strike the enemy before the enemy had a time to respond. We know from present air combat, that stealth can give a force a huge advantage, in the ability to strike first and escape before detection.

I agree that stealth would be costly. That is why it would probably be reserved for fighters not capital ships. A stealth space fighter would probably be almost impossible to detect.

A space fighter would be rather small compared to a capital ship, so would it be able to carry enough firepower to even hurt a capital ship?

quote: Originally posted by Sandman Finally, a stealth ship would be very vulnerable to lasers.

Why? Any stealth material that is made to absorb radar signals would not necessarily aborb lasers the same way. The wavelengths would be completely different.

Also, remember that a stealth ship would be very difficult to detect, and you have to find the ship before you can shoot it!

	05-06-2003 00:37									#87
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There would be very little need for Stealth in space for the reasons MtG stated earlier. An actiuve search system would be suicide, announcing to everyone where you are, while having a low likelihood of finding anyone. Sensors would most likely be passive. Shieding then would be to keep in radiation, or dissipating it, specially exhaust from the engines.

	05-06-2003 00:40									#88
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quote: Originally posted by The diplomat True, but stealth would give a force a huge first strike advantage. A ship with stealth features in both radar spectrum, visible spectrum, infrared spectrum, would be very difficult to detect....

A stealth vehicle invisible to IR sensors IN SPACE????

That means the whole ship has to be about absolute zero - very chilly for the crew!

I honestly don't see how you could have stealth in IR frequencies. Radio yes, light yes, but heat? That's the product of just about every physical process.

Anyone got any bright ideas on this?

	05-06-2003 00:50									#89
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quote: Originally posted by GePap There would be very little need for Stealth in space for the reasons MtG stated earlier. An active search system would be suicide, announcing to everyone where you are, while having a low likelihood of finding anyone. Sensors would most likely be passive. Shieding then would be to keep in radiation, or dissipating it, specially exhaust from the engines.

Just like subs reduce their noise output to prevent passive detection, spaceships would want to reduce the amount of EM noise they put out into space to prevent passive detection.

Ships might not want to use active sensors, but you would still probably want weapons to use them. For example, a missile would need an active sensor, like a radar, in order to home in on its target. It would be almost impossible to hit a target without one. So, stealth could still be useful in reducing the chance of enemy weapons locking on to you.

	05-06-2003 01:07									#90
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quote: True, but stealth would give a force a huge first strike advantage. A ship with stealth features in both radar spectrum, visible spectrum, infrared spectrum, would be very difficult to detect. Such a ship could sneak in and strike the enemy before the enemy had a time to respond. We know from present air combat, that stealth can give a force a huge advantage, in the ability to strike first and escape before detection.

Well, Cruddy got there before me about the IR problem. Secondly, there's no guarantee that detection technology won't keep pace with stealth developments. Stealth is not that effective today, it's expensive, the planes are slow and otherwise defenseless, they need to fly at night, and they carry a small payload of weapons.

quote: Why? Any stealth material that is made to absorb radar signals would not necessarily aborb lasers the same way. The wavelengths would be completely different.

It would have to absorb optical light, otherwise you'd see it.

quote: Anyone got any bright ideas on this?

1. Internal heat absorbing systems. These soak up a limited amount of heat when the ship wants to be 'quiet'. The only problem is the limited size means that the heat has to be dumped somehow, otherwise the ship will overheat. When the ship is in a safe area, it could dump the built up heat via IR or by ejecting heated capsules.

2. Concealed radiator. The ship dissipates heat through a radiator that is angled so that it is out of enemy observation. Of course, the enemy could place passive observers all over space to eliminate this possibility.