Necro about stealth in space split from some unknown thread.

[tater]

No stealth is entirely reasonable. 

Edited August 19, 2018 by tater

[Diche Bach]

On 11/12/2017 at 5:42 PM, tater said:

No stealth is entirely reasonable. 

Stealth being very difficult for a highly advanced solar system is entirely reasonable. Stealth being non-existent is silly under any circumstances. One does not have to be invisible to be stealthy. Stealth is just one variety of crypsis and crypsis can take on many forms. D-Day managed to be fairly cryptic despite a complete lack of "stealth" in the modern sense of the term. Human beings are far too cunning to presume that "no stealth is entirely reasonable."

Still, it does seem reasonable that stealth would be quite problematic and require exceptional efforts and highly specialized (thus restrictive, expensive and niche designs) space ship engineering. With that in mind, leaving it out of the game seems like a perfectly reasonable design decision. But that is a design decision based on project scope and resources, not "realism." In a truly realistic space warfare sim, crypsis of various forms would be at least as paramount as it is today in modern international relations and quite possibly moreso by virtue of the vast distances, enormous populations and myriad hiding places.

[tater]

No, in space you radiate basically all generated energy. A spacecraft with a crew is a bright IR object at long range. If it operates an engine capable of meaningful, particularly "sci fi" level thrusts (travel within the solar system in time frames not measured in years between A and B), then the ships is so bright as to be obvious to anyone.

The only possible physics solution would be magical radiators that were narrowly directional, and those presume that the craft in question knows where the enemy's sensors are so as to not point at them.

The bottom line is that an operating spacecraft cannot hide, sorry. It's a physics problem. Anything above 2.725 K is going to be detected at some range. "Room temperature" (20°C) spacecraft are incredibly bright objects. Operating engines are far brighter. Maybe you could use solar sails, for example, but then your trip from one part of the solar system to another would result in your crew dying of old age before they can attack their (now also dead of old age) enemies.

Edited November 18, 2017 by tater

[HebaruSan]

24 minutes ago, tater said:

No, in space you radiate basically all generated energy. A spacecraft with a crew is a bright IR object at long range.

And without a crew?

24 minutes ago, tater said:

If it operates an engine capable of meaningful, particularly "sci fi" level thrusts

I thought CoaDE didn't have sci fi engines. The few gameplay examples I saw involved KSP-like orbital dynamics, which at least suggests there aren't torchships.

24 minutes ago, tater said:

(travel within the solar system in time frames not measured in years between A and B),

We have ample precedent for multi-year wars in the past century or two.

24 minutes ago, tater said:

The only possible physics solution would be magical radiators that were narrowly directional, and those presume that the craft in question knows where the enemy's sensors are so as to not point at them.

Pointing it at a random spot is still better than pointing it everywhere. Which percentage chance of detection would you prefer, 5% or 100%?

24 minutes ago, tater said:

The bottom line is that an operating spacecraft cannot hide, sorry. It's a physics problem. Anything above 2.725 K is going to be detected at some range. "Room temperature" (20°C) spacecraft are incredibly bright objects. Operating engines are far brighter. Maybe you could use solar sails, for example, but then your trip from one part of the solar system to another would result in your crew dying of old age before they can attack their (now also dead of old age) enemies.

The best method is probably the least technical: blend in with the thousands of other crafts operating in the solar system and conceal your hostile intentions till the last possible moment. When in doubt, steal enemy transponder codes and affix fake cargo containers to your hull.

[tater]

1 hour ago, HebaruSan said:

And without a crew?

Does it have a power source capable of running a meaningful drive (fast travel, not years to get someplace) or power a directed energy weapon? Then it's visible.

1 hour ago, HebaruSan said:

I thought CoaDE didn't have sci fi engines. The few gameplay examples I saw involved KSP-like orbital dynamics, which at least suggests there aren't torchships.

If you can get places in weeks, not many years, they're visible.

1 hour ago, HebaruSan said:

We have ample precedent for multi-year wars in the past century or two.

There are not human civilizations around different parts of the solar system without better drives than solar sails. Explain the context that results in war in this game, as well as typical travel times. They must have NTRs at the very least, right?

 

1 hour ago, HebaruSan said:

Pointing it at a random spot is still better than pointing it everywhere. Which percentage chance of detection would you prefer, 5% or 100%?

One, you can't beam heat in that narrow a direction without science fiction (read: fantasy) radiators. Two, again, you can maybe pick some large fraction of sky to try and send waste heat, you have now mitigated detection only to the extent there are no sensors that way. The counter is to throw sensor satellites around the solar system. If directional radiators are a thing, then anyone building warships would spam such sensors.

1 hour ago, HebaruSan said:

The best method is probably the least technical: blend in with the thousands of other crafts operating in the solar system and conceal your hostile intentions till the last possible moment. When in doubt, steal enemy transponder codes and affix fake cargo containers to your hull.

That's fine, but not stealth. Stealth is making a ship invisible at some range, and less visible at some shorter range. 

[HebaruSan]

2 hours ago, tater said:

Does it have a power source capable of running a meaningful drive (fast travel, not years to get someplace) or power a directed energy weapon? Then it's visible.

I don't know. Maybe it's just a dumb projectile. Maybe it's dormant till it gets to close range.

2 hours ago, tater said:

If you can get places in weeks, not many years, they're visible.

OK, so suppose it's years, because the attacker wants stealth.

2 hours ago, tater said:

There are not human civilizations around different parts of the solar system without better drives than solar sails. Explain the context that results in war in this game, as well as typical travel times. They must have NTRs at the very least, right?

I haven't played it, but it's easy enough to make things up. Let's start with resource squabbles, or maybe religious conflict.

2 hours ago, tater said:

One, you can't beam heat in that narrow a direction without science fiction (read: fantasy) radiators. Two, again, you can maybe pick some large fraction of sky to try and send waste heat, you have now mitigated detection only to the extent there are no sensors that way. The counter is to throw sensor satellites around the solar system. If directional radiators are a thing, then anyone building warships would spam such sensors.

... and anyone else building warships would destroy such satellites as quickly as they were placed, which wouldn't be very quickly without torch drives. I'd love to see the cost estimate on a swarm of thousands of orbital LSSTs.

[tater]

3 hours ago, HebaruSan said:

I don't know. Maybe it's just a dumb projectile. Maybe it's dormant till it gets to close range.

Then it was likely detected when it was launched and formed a trajectory. If you are counting on a target being in the same place months or years from now... good luck with that.

3 hours ago, HebaruSan said:

OK, so suppose it's years, because the attacker wants stealth.

What makes them think there will be a target within a few km of the target point years hence?

3 hours ago, HebaruSan said:

I haven't played it, but it's easy enough to make things up. Let's start with resource squabbles, or maybe religious conflict.

Not terribly plausible.

3 hours ago, HebaruSan said:

... and anyone else building warships would destroy such satellites as quickly as they were placed, which wouldn't be very quickly without torch drives. I'd love to see the cost estimate on a swarm of thousands of orbital LSSTs.

They are cheaper than warships, and use (and hence radiate) less power.

[HebaruSan]

1 hour ago, tater said:

Then it was likely detected when it was launched and formed a trajectory. If you are counting on a target being in the same place months or years from now... good luck with that.

Unless the attacker took some action to disguise it or distract the enemy, etc. You know, like a military might do if they were launching an attack. Or if there were tens of thousands of ships flying all over the solar system and nothing unusual about this one from a distance, especially to a robo-telescope that has to sift through GB of data per hour.

1 hour ago, tater said:

What makes them think there will be a target within a few km of the target point years hence?

You'd have to ask their intelligence services, but there are many possibilities. First thing that comes to mind is targeting ground installations, second is very wide-effect weaponry, third is course adjustments later on, fourth is targeting a shipping lane and picking a specific ship later.

1 hour ago, tater said:

Not terribly plausible.

Ha!

1 hour ago, tater said:

They are cheaper than warships, and use (and hence radiate) less power.

Oh no, your spy satellites do not get to be stealthier than my weapons just because. They'll also be detected when they're launched and form a trajectory. And they'll be constantly beaming full-sky surveys to your HQ, which not only requires them to radiate heat, but also gives me the opportunity to stumble across the actual comms channel.

To conclude: The objections raised are constraints on space stealth, not dealbreakers. They're things you'd have to keep in mind if you wanted to attempt (or write hard sci-fi about) stealth operations, not reasons why they can't be done. Yes, you'd need to control temperatures carefully. Yes, you have to be very conscious of your burns, and ideally find ways of masking them. Yes, your enemy might have an infinite field of spy satellites, or they might not, especially if you intervene. These are all challenges that some future space military might well accept.

[tater]

4 minutes ago, HebaruSan said:

Unless the attacker took some action to disguise it or distract the enemy, etc. You know, like a military might do if they were launching an attack. Or if there were tens of thousands of ships flying all over the solar system and nothing unusual about this one from a distance, especially to a robo-telescope that has to sift through GB of data per hour.

You can't disguise anything. What, they send a ship on a trajectory... you now know where it will be forever, unless it maneuvers, which you will also see. 

4 minutes ago, HebaruSan said:

You'd have to ask their intelligence services, but there are many possibilities. First thing that comes to mind is targeting ground installations, second is very wide-effect weaponry, third is course adjustments later on, fourth is targeting a shipping lane and picking a specific ship later.
 

That's fine, but with the exception of maybe solar sails, it's likely detected, and even those reflect light by definition, so those might be detected, too. So you need a war where things happen perhaps over decades. If you are aiming for land targets, drop rocks, BTW.

That's another reason for no wars.

4 minutes ago, HebaruSan said:

Ha!

There are no resources worth fighting over, because there are too many resources. 

We're talking about manned spacecraft, right? 

4 minutes ago, HebaruSan said:

Oh no, your spy satellites do not get to be stealthier than my weapons just because. They'll also be detected when they're launched and form a trajectory. And they'll be constantly beaming full-sky surveys to your HQ, which not only requires them to radiate heat, but also gives me the opportunity to stumble across the actual comms channel.

This is true, but they are smaller, so the detection distance is likely shorter to see them. They are certainly cheaper. Their beaming is very narrow, because they aim at a planet, then the planet broadcasts to the ships. Comms can actually be directional, unlike radiators, or rocket exhaust. The sensors are also placed before any war, the war has to start sometime, right?

4 minutes ago, HebaruSan said:

To conclude: The objections raised are constraints on space stealth, not dealbreakers. They're things you'd have to keep in mind if you wanted to attempt (or write hard sci-fi about) stealth operations, not reasons why they can't be done. Yes, you'd need to control temperatures carefully. Yes, you have to be very conscious of your burns, and ideally find ways of masking them. Yes, your enemy might have an infinite field of spy satellites, or they might not, especially if you intervene. These are all challenges that some future space military might well accept.

No, physics breaks stealth. There is no stealth, there are constraints on detection ranges, etc, but there is no such thing as making spacecraft effectively unseen, which is what stealth is.

If space warfare were to only consist of 1 ton probes shooting each other, what's the point, exactly? This game seems to show pretty large warships, for reasons. 

This is not controversial, stealth in space was debunked decades ago, back when I was having this discussion on USENET groups. If you want spacecraft hiding in space, you have to stick to fantasy universes, sadly.

 

I'd try this out, but it's on Steam, and I don't do steam.

 

22 minutes ago, HebaruSan said:

Oh no, your spy satellites do not get to be stealthier than my weapons just because. They'll also be detected when they're launched and form a trajectory. And they'll be constantly beaming full-sky surveys to your HQ, which not only requires them to radiate heat, but also gives me the opportunity to stumble across the actual comms channel.

I need to expand on this a little.

Presume some ability to mask emissions, like directional radiators (which is possible, but only over a pretty wide arc, it's not like a laser). So there, you have stealth of a sort. That means I have the same stealth for tiny, passive sensors that radiate their few watts of heat away. I spam many, many of them. You can know where they went, but you cannot now point radiators anywhere (you'd still be radiating over an area that is a large % of the sky, after all). If you need to use any maneuvering, you're detected regardless, the small sensors or for catching non-maneuvering objects based on waste heat. Nearly maneuver is observed at solar system distances. Any maneuver designed to shape trajectories over reasonable human timespans is detectable.

Again, who is having a war not expected to take any sort of shape until after you children (of a dead earth?) are long dead, since you maneuvered with so little energy that your warship will be in range of something, maybe, in 100 years.

[tater]

Also, the range matters. being able to do something unseen in the Kuiper Belt is possible, for example, but only meaningful if you can then act on it within some useful time period. The range of stealth that matters in combat, is some multiple of weapon range. You could be 100% stealthy if you did your maneuver in another star system, we'd all agree on that. But it's be thousands of years before your craft is at our solar system, so it;s safe to ignore that as a case.

So I would argue that stealth is a meaningless concept for any system that cannot engage a target within some time period we'd have to agree on. How many years should that be?

[WinkAllKerb'']

i do wonder if you two plan to marry someday ^^ 

Edited November 20, 2017 by WinkAllKerb''
pm

[Diche Bach]

Stealth in Space is Possible

[weissel]

On 27/11/2017 at 12:00 AM, Diche Bach said:

Stealth in Space is Possible

And now read the Atomic Rockets website and find out that "stealth" again is relative.

Yes, you likely can use hydrogen or helium to dump heat and expel the waste (or use it for thrust, too) while being hard to see.

And now imagine you were the guy in charge of protecting your planet/asteroid/system from threats like these "stealth ships".

• Are you going to have lots of small, cheap drones around that look for heat signatures?  Sure you would.
• How about drones scanning everything nearby with Radar or Lidar or similar?  Sure you would, even if they are more costly and visible to all due to their higher power use and active radar/lidar use.  And if they are attacked, that in itself is an important alert signal.
• How about extensive surface systems, which can be totally stealthed under ground, both for observation and for counterattacks?  As much as the budget can be squeezed and then some!
• How about organising a 24/7 watch on the brightness of all stars bright enough to be of use?  No problem!  We routinely do monitor star brightness of stars over months and years, detecting tiny dips of 0.1%, which shows us there's a planet crossing the star far away.  All that is needed are some large aperture lenses (apparently the old 200mm f1.8 Canon lenses do great work for a very low price --- compared to specially made optics, at least) and sensitive sensors (current DSLRs have fairly good sensors, enough for that work) and some software for tracking and finding the stars on the photos and measuring the brightness.  Which we all have today.
• I am pretty sure you'll find some other ideas --- even a very sparse, but wide hydrogen stream at 9km/s (and 22K) should be detectable with matching active sensors.  I am thinking of something not quite dissimilar to Michelson-Morley (trying to detect the Aether which obviously failed due to non-existent Aether --- but that hydrogen cloud exists ...).

All that being given, do you see a role for spy craft of that kind?  And if so, will they (at 190m/s per day) be manoeuvrable enough for any kind of battle where they are detected?  (I guess no.  Once they are detected in any way, any dumb kinetic weapon will take them out, they cannot dodge at all.

 

So yes, you may have some stealth in space --- given very special circumstances --- and now tell me, what can you do with it?

[FennexFox]

To anyone who truly believe there's no stealth in space: Just stop being a nerd and take a look how REAL military fights. Never say any repurposed bovine waste anymore.

 

The fact that you can detect a ship from a distance doesn't mean you broke his/her stealth. You have to locate the ship accurate enough to direct your gun to hit the ship. THAT'S WHY SOLDIERS WEAR CAMO. If the ship is directionally stealthy, you have to rely on remote sensors to locate them. At least 3 to triangulate, preferably more than 10 to be quick and accurate enough. Keep in mind that every single asset in battlefield is limited, including comms and processors. If aggressors are many enough, you can't triangulate everyone with the remote sensor at once, so they can reduce the chance to be hit: THAT'S WHAT STEALTH IS FOR. Even if you can triangulate them all, you have to get a data link from the sensors and you're not the only ship want it. Only a part of your fleet can get data in time so that limit your firepower. THAT'S WHAT STEALTH IS FOR. If you have established a central comms and processing node that can get every data from the remote sensors and can send the data to every single ship of your fleet, that would be the bottleneck or weak point. Aggressors can try to destroy the central node to neutralize or at least make your fleet less accurate. THAT'S CALLED SEAD. Don't forget you don't need to have the bottleneck if the enemy is not directionally stealthy. THAT'S WHAT STEALTH IS FOR.

Even if you can get over every obstacles and be able to defeat your stealthy enemy, you have spent a lot of resources you wouldn't have to if they're not stealthy. THAT'S WHAT STEALTH IS FOR.

Edited August 15, 2018 by FennexFox

[weissel]

On 8/15/2018 at 6:31 AM, FennexFox said:

To anyone who truly believe there's no stealth in space: Just stop being a nerd and take a look how REAL military fights.

Well, the REAL^(tm) military ... has fired a gun in space, once, just to find out if they could hit a simple, non-maneuvering object.  That did get a bit Kessler, too.  Ballistic Missiles don't count, they are to space combat what a hot air balloon from besieged Paris is to air combat.  And "Star Wars" AKA SDI has never reached operational status, never mind fought (and that would be against ICBSs, which do not evade or counter-attack).

And to my knowledge the Trumpian Space FarceForce is not yet there, either.

Which REAL^(tm) military were you refering to, then?

Oh, I see ... you are talking about ground troops.  That's like the "Königin Louisa" here:
which surely is a most excellent air combattant, and once you cross their T you really have the enemy.  (See the original web page, with more photos and the history of the "real life" vessel which this model shows.)

As you can see, Jules Verne's 1886 novel "Robur-le-Conquérant" ("Robur the Conqueror", also known as "The Clipper of the Clouds") predicts the very same model of air vessels.

As you can see, this would be the very way  the real military fights.  On the sea, that is, where the Immelmann, the scissors or the barrel roll were ... ah, rarely performed.

Though of course, we can go and do space fights on the analogy of pike square tactics, seeing that the real military used it from the last quarter of the 15th century to the mid-17th century to great effect on those who did not use it.  (And it fell out of favour only after firearms were much improved and hand to hand fighting, even against charging cavalry, became rare and the bayonet helped out in these rare cases.)

 

On 8/15/2018 at 6:31 AM, FennexFox said:

The fact that you can detect a ship from a distance doesn't mean you broke his/her stealth.

Let us assume you could detect the presence, number, movement and pretty accurate position of all enemy soldiers less than 100km away, under all circumstances (no hills, trees, bunkers, horizon ...).
Let us also assume your effective fighting range was around 600-1000m.

Would the detection ability change the way you fight?

If yes, then yes, you broke operational stealth.  The kind you need the enemy not to break when you lure them into a trap.  Imagine how the Battle of Jutland --- where both sides tried to get the other side to run into an ambush --- would have been fought if one or both sides had known reliably where the other sides' forces were, even with an error of 10km.

If no, then sorry, I disbelieve you.

 

On 8/15/2018 at 6:31 AM, FennexFox said:

You have to locate the ship accurate enough to direct your gun to hit the ship. THAT'S WHY SOLDIERS WEAR CAMO.

Oh, did I mention lasers yet?  At the ranges we are talking about, they are hitscan weapons.  You fire them directly at the target, no bullet drop, no relevant time delay even at 30,000 km (about 2/10s, there and back), boom.  Range does almost never matter, just angle, and that you can get just fine. Pointing your laser accurately enough is much more of a challenge.  No camo will help.  You need to stay invisible.

 

On 8/15/2018 at 6:31 AM, FennexFox said:

 If the ship is directionally stealthy, you have to rely on remote sensors to locate them. At least 3 to triangulate, preferably more than 10 to be quick and accurate enough.

Let's see ... "directional stealth".  That sums up to a lot of weight.  Weight you are not using for reaction mass, weapons, stores, sensors, creature comfort.  Weight that will reduce your dV.

And you only need 2 remote sensors:

• Position of remote sensor: Lidar, possibly with a transponder, from the defender
• Target angle: Simply photograph the target and get the brighter stars in the same frame, too.  Startracker software --- especially if you have an idea of your orientation in space, say from said star tracker --- finds out which stars they are (that is very much today's technology), pixel counting tells you the angles.
• 2 lines intersect at the enemy vessel.

Done.

And that does not even count active sensors like lidar and radar from the defender.  Does your stealthing handle those?
The remote sensors can use radar and lidar, too, BTW.
If you cross in front of a star from any kind of remote sensor anywhere in the system, you give another data point --- the largest problem would be the time for a sensor many light minutes behind the defender and agressor to detect and for that report to reach the defender.

And it does not handle any weapon with sensors and the capability to change its path of flight.  Missiles, for example.  Who'd also report all the data they get back home.  Or drones.  They can simply zig out of the stealth shadow and then get in on you.

Finally, you do know that your maneuverability is severely restricted if you need to keep the defender in your stealth cone.  Which makes you a much less, if at all, maneuverable target, i.e. a much easier target.

 

On 8/15/2018 at 6:31 AM, FennexFox said:

Keep in mind that every single asset in battlefield is limited, including comms and processors. If aggressors are many enough, you can't triangulate everyone with the remote sensor at once, so they can reduce the chance to be hit: THAT'S WHAT STEALTH IS FOR.

The comms and processor needs here are trivial.  It's like worrying that a game of chess by email might overwhelm the internet in a world of netflix streaming.  If the agressors are --- how many is "many enough?"  Are we talking about 50+ versus one or 2 defenders (assuming similar tonnage for all vessels)?  In which case the combat power of the attackers is going to overwhelm the defenders handily and tactical stealth does not matter.

Or are we talking a roughly 1:1 or 2:1 ratio?  In this case each defender needs to "handle" only 1 or 2 attackers, the combat network will pass all information between the defenders, no problem.  Position + orientation + movement vector data for an attacker is shorter than this sentence ...

The limitations on orientation and therefore direction and speed changes given by needing to keep directional stealth aligned is a huge drawback.  Especially when you are in effective range against a little maneuvering enemy but not against a freely maneuvering one --- think of bullets & co with a number of seconds of flight time.  Enough time to dodge, if you move freely.  That really is increasing the chance to be hit.

 

On 8/15/2018 at 6:31 AM, FennexFox said:

Even if you can triangulate them all, you have to get a data link from the sensors and you're not the only ship want it. Only a part of your fleet can get data in time so that limit your firepower. THAT'S WHAT STEALTH IS FOR.

You have heard of "omnidirectional antennae"?
And of tactical data links?  It's not like the defender is trying to hide it's position or that their vessels cannot talk to one another.  And yes, they could use laser comms if they want to.

64bit (8 byte) is enough for sub-mm resolution many times beyond Pluto.

• A position: 3 values @ 64 bit (24 bytes total), e.g.
  • Distance from the centre of the system
  • angle against the ecliptic (or height above/below it)
  • angle to the galactic centre
• An orientation.  3 values @ 16 bit (6 bytes total) --- this is enough for a better than 0.01° accuracy --- for pitch, roll, yaw
• A speed vector.  3 values @ 24 bit (9 bytes total) --- this is enough for a better than 0.01 m/s accuracy up to 100 km/s (which probably is enough unless you are *very* close to the sun), if needed we can always slap on more bits.
• An acceleration vector: let's say another 6 bytes.
• An angular velocity vector.  6 bytes should do it.
• An angular acceleration vector.  Oh hell, another 6 bytes.
• A vessel ID/name/type: let's assume 16 million targets is enough, that is 3 bytes.

That would be a whopping 60 byte, and we have not yet talked about any kind of compression/reduction.  Likely we will not have a combat space from several times beyond Pluto to several times beyond it on the other side of the solar system.  Likely the speed will not change by 5km/s per second, so we can do with a delta. etc.

But yes, 273 complete data sets per second --- which is about what an 128kBit MP3-stream has --- will knock out the data links.

On 8/15/2018 at 6:31 AM, FennexFox said:

If you have established a central comms and processing node that can get every data from the remote sensors and can send the data to every single ship of your fleet, that would be the bottleneck or weak point. Aggressors can try to destroy the central node to neutralize or at least make your fleet less accurate. THAT'S CALLED SEAD. Don't forget you don't need to have the bottleneck if the enemy is not directionally stealthy. THAT'S WHAT STEALTH IS FOR.

And that is why you do not do a Napster with one central node.  That is why you use a decentralised system.  That is why you build a redundant system. That is why any vessel can take over every role of every other vessel when it comes to monitoring and enemy position calculation.

Which you would do anyway because it's good design.

On 8/15/2018 at 6:31 AM, FennexFox said:

Even if you can get over every obstacles and be able to defeat your stealthy enemy, you have spent a lot of resources you wouldn't have to if they're not stealthy. THAT'S WHAT STEALTH IS FOR.

And you have spent vastly more resources on hauling around all that directional stealth and the gear to look around it, and the gear to fire "over" it (you cannot look or fire through it.  And if you want to stay stealthy, you better super-cool your sensors and weapons peaking over it, as well) and the lower acceleration and the maneuvre constraints and the wasted dV and the less efficient radiators.  All that stuff just so you could be an easier target as you cannot maneuvre without giving up any advantages of that expensive toy of yours may have ... and you still get shot up.  THAT'S WHAT STEALTH DOES TO YOU.

The idea --- be harder to hit --- is of course sound.  The difference is that camo for soldiers is very lightweight and blends easily in with the background while not hindering movement at all and making them mostly invisible to their enemies if they take advantage of the environment.  That is very much not true for space vessels, there are quite significant drawbacks and the threat profile faced by infantry does not usually include (nuclear tipped) homing missiles and the kind of drones we see or lasers reaching 100s of kilometres or 10 km/s projectiles ...

You may as well say that because infantry soldiers hide behind walls and in depressions and tend to dive into bunkers or at least trenches and craters when artillery comes a-calling, battleships should act the same way.  (That'd be a submarine, which usually does not have a big battleship size gun[1] and certainly not the armor.)   And as soldiers have a helmet and a flak-vest, there should be no armour on battleships.  And battleships should carry just a rifle or two, maybe an MG when several are around to carry the ammo.  Does not make sense, but that is how "real military" fights --- in totally different circumstances, but still ...
 

[1] The M-Class submarines of the Royal Navy (1917/1918) had a single 12" gun, which could be fired (but not reloaded) submerged, from gun spares of the Formidable-class battleships.  Torpedoes were seen as unreliable beyond 1000m against faster moving ships and a single shell should kill most merchant vessels.  None saw combat.
The Surcouf (French submarine) had a 2-gun turret with 8" heavy cruiser guns and 600 shot, as well as an observation floatplane.  It was a cruiser submarine --- designed to be a cruiser, as the Washington Naval Treaty limited cruisers, but not submarines.  This was fixed soon after the launch by the London Naval Treaty, making her one of a kind.  She was lost in Febuary 1942 to either friendly fire or accidental collision at night (or both), not having fired shots in anger.  (There was a fight with 4 dead, but that was side arms, when the British, fearing the French Fleet to fall into the hands of the Kriegsmarine at a French armistice --- see also Mers-el-Kebir.)

 

8 hours ago, FennexFox said:

+ Here's a trap tho: You have to beat a few campaign to unlock the ship design, and much more to module design.

...  or you flick the not-so-secret switch to enable ship and module design from the get go.  You will have to do the relevant campaign missions without these possibilities, but otherwise you are fine.

And you might even learn a thing or two doing the campaign missions.

[FennexFox]

On ‎8‎/‎17‎/‎2018 at 4:02 PM, weissel said:

Well, the REAL^(tm) military ... has fired a gun in space, once, just to find out if they could hit a simple, non-maneuvering object.  That did get a bit Kessler, too.  Ballistic Missiles don't count, they are to space combat what a hot air balloon from besieged Paris is to air combat.  And "Star Wars" AKA SDI has never reached operational status, never mind fought (and that would be against ICBSs, which do not evade or counter-attack).

And to my knowledge the Trumpian Space FarceForce is not yet there, either.

Which REAL^(tm) military were you refering to, then?

Oh, I see ... you are talking about ground troops.  That's like the "Königin Louisa" here:
which surely is a most excellent air combattant, and once you cross their T you really have the enemy.  (See the original web page, with more photos and the history of the "real life" vessel which this model shows.)

As you can see, Jules Verne's 1886 novel "Robur-le-Conquérant" ("Robur the Conqueror", also known as "The Clipper of the Clouds") predicts the very same model of air vessels.

As you can see, this would be the very way  the real military fights.  On the sea, that is, where the Immelmann, the scissors or the barrel roll were ... ah, rarely performed.

Though of course, we can go and do space fights on the analogy of pike square tactics, seeing that the real military used it from the last quarter of the 15th century to the mid-17th century to great effect on those who did not use it.  (And it fell out of favour only after firearms were much improved and hand to hand fighting, even against charging cavalry, became rare and the bayonet helped out in these rare cases.)

 

Let us assume you could detect the presence, number, movement and pretty accurate position of all enemy soldiers less than 100km away, under all circumstances (no hills, trees, bunkers, horizon ...).
Let us also assume your effective fighting range was around 600-1000m.

Would the detection ability change the way you fight?

If yes, then yes, you broke operational stealth.  The kind you need the enemy not to break when you lure them into a trap.  Imagine how the Battle of Jutland --- where both sides tried to get the other side to run into an ambush --- would have been fought if one or both sides had known reliably where the other sides' forces were, even with an error of 10km.

If no, then sorry, I disbelieve you.

 

Oh, did I mention lasers yet?  At the ranges we are talking about, they are hitscan weapons.  You fire them directly at the target, no bullet drop, no relevant time delay even at 30,000 km (about 2/10s, there and back), boom.  Range does almost never matter, just angle, and that you can get just fine. Pointing your laser accurately enough is much more of a challenge.  No camo will help.  You need to stay invisible.

 

Let's see ... "directional stealth".  That sums up to a lot of weight.  Weight you are not using for reaction mass, weapons, stores, sensors, creature comfort.  Weight that will reduce your dV.

And you only need 2 remote sensors:

• Position of remote sensor: Lidar, possibly with a transponder, from the defender
• Target angle: Simply photograph the target and get the brighter stars in the same frame, too.  Startracker software --- especially if you have an idea of your orientation in space, say from said star tracker --- finds out which stars they are (that is very much today's technology), pixel counting tells you the angles.
• 2 lines intersect at the enemy vessel.

Done.

And that does not even count active sensors like lidar and radar from the defender.  Does your stealthing handle those?
The remote sensors can use radar and lidar, too, BTW.
If you cross in front of a star from any kind of remote sensor anywhere in the system, you give another data point --- the largest problem would be the time for a sensor many light minutes behind the defender and agressor to detect and for that report to reach the defender.

And it does not handle any weapon with sensors and the capability to change its path of flight.  Missiles, for example.  Who'd also report all the data they get back home.  Or drones.  They can simply zig out of the stealth shadow and then get in on you.

Finally, you do know that your maneuverability is severely restricted if you need to keep the defender in your stealth cone.  Which makes you a much less, if at all, maneuverable target, i.e. a much easier target.

 

The comms and processor needs here are trivial.  It's like worrying that a game of chess by email might overwhelm the internet in a world of netflix streaming.  If the agressors are --- how many is "many enough?"  Are we talking about 50+ versus one or 2 defenders (assuming similar tonnage for all vessels)?  In which case the combat power of the attackers is going to overwhelm the defenders handily and tactical stealth does not matter.

Or are we talking a roughly 1:1 or 2:1 ratio?  In this case each defender needs to "handle" only 1 or 2 attackers, the combat network will pass all information between the defenders, no problem.  Position + orientation + movement vector data for an attacker is shorter than this sentence ...

The limitations on orientation and therefore direction and speed changes given by needing to keep directional stealth aligned is a huge drawback.  Especially when you are in effective range against a little maneuvering enemy but not against a freely maneuvering one --- think of bullets & co with a number of seconds of flight time.  Enough time to dodge, if you move freely.  That really is increasing the chance to be hit.

 

You have heard of "omnidirectional antennae"?
And of tactical data links?  It's not like the defender is trying to hide it's position or that their vessels cannot talk to one another.  And yes, they could use laser comms if they want to.

64bit (8 byte) is enough for sub-mm resolution many times beyond Pluto.

• A position: 3 values @ 64 bit (24 bytes total), e.g.
  • Distance from the centre of the system
  • angle against the ecliptic (or height above/below it)
  • angle to the galactic centre
• An orientation.  3 values @ 16 bit (6 bytes total) --- this is enough for a better than 0.01° accuracy --- for pitch, roll, yaw
• A speed vector.  3 values @ 24 bit (9 bytes total) --- this is enough for a better than 0.01 m/s accuracy up to 100 km/s (which probably is enough unless you are *very* close to the sun), if needed we can always slap on more bits.
• An acceleration vector: let's say another 6 bytes.
• An angular velocity vector.  6 bytes should do it.
• An angular acceleration vector.  Oh hell, another 6 bytes.
• A vessel ID/name/type: let's assume 16 million targets is enough, that is 3 bytes.

That would be a whopping 60 byte, and we have not yet talked about any kind of compression/reduction.  Likely we will not have a combat space from several times beyond Pluto to several times beyond it on the other side of the solar system.  Likely the speed will not change by 5km/s per second, so we can do with a delta. etc.

But yes, 273 complete data sets per second --- which is about what an 128kBit MP3-stream has --- will knock out the data links.

And that is why you do not do a Napster with one central node.  That is why you use a decentralised system.  That is why you build a redundant system. That is why any vessel can take over every role of every other vessel when it comes to monitoring and enemy position calculation.

Which you would do anyway because it's good design.

And you have spent vastly more resources on hauling around all that directional stealth and the gear to look around it, and the gear to fire "over" it (you cannot look or fire through it.  And if you want to stay stealthy, you better super-cool your sensors and weapons peaking over it, as well) and the lower acceleration and the maneuvre constraints and the wasted dV and the less efficient radiators.  All that stuff just so you could be an easier target as you cannot maneuvre without giving up any advantages of that expensive toy of yours may have ... and you still get shot up.  THAT'S WHAT STEALTH DOES TO YOU.

The idea --- be harder to hit --- is of course sound.  The difference is that camo for soldiers is very lightweight and blends easily in with the background while not hindering movement at all and making them mostly invisible to their enemies if they take advantage of the environment.  That is very much not true for space vessels, there are quite significant drawbacks and the threat profile faced by infantry does not usually include (nuclear tipped) homing missiles and the kind of drones we see or lasers reaching 100s of kilometres or 10 km/s projectiles ...

You may as well say that because infantry soldiers hide behind walls and in depressions and tend to dive into bunkers or at least trenches and craters when artillery comes a-calling, battleships should act the same way.  (That'd be a submarine, which usually does not have a big battleship size gun[1] and certainly not the armor.)   And as soldiers have a helmet and a flak-vest, there should be no armour on battleships.  And battleships should carry just a rifle or two, maybe an MG when several are around to carry the ammo.  Does not make sense, but that is how "real military" fights --- in totally different circumstances, but still ...
 

[1] The M-Class submarines of the Royal Navy (1917/1918) had a single 12" gun, which could be fired (but not reloaded) submerged, from gun spares of the Formidable-class battleships.  Torpedoes were seen as unreliable beyond 1000m against faster moving ships and a single shell should kill most merchant vessels.  None saw combat.
The Surcouf (French submarine) had a 2-gun turret with 8" heavy cruiser guns and 600 shot, as well as an observation floatplane.  It was a cruiser submarine --- designed to be a cruiser, as the Washington Naval Treaty limited cruisers, but not submarines.  This was fixed soon after the launch by the London Naval Treaty, making her one of a kind.  She was lost in Febuary 1942 to either friendly fire or accidental collision at night (or both), not having fired shots in anger.  (There was a fight with 4 dead, but that was side arms, when the British, fearing the French Fleet to fall into the hands of the Kriegsmarine at a French armistice --- see also Mers-el-Kebir.)

 

...  or you flick the not-so-secret switch to enable ship and module design from the get go.  You will have to do the relevant campaign missions without these possibilities, but otherwise you are fine.

And you might even learn a thing or two doing the campaign missions.

I just want to remind you that even Gerald Ford class CVN, one of the most biggest ship mankind ever had, is still struggling to get STEALTH for its only partial fraction. Way easier target than a multi square kilometer cross section space warship megameters away. Now say that whatever stealth you have made is useless on the naval surface because of tidal trace, wave it faces,  and so much of blah blah, and say that again to the REAL admirals who spend tons of budget and manpower. Note that it doesn't want to be invisible, just to be harder to hit.

Stealth is not completely being transparent from enemy. It's rather destined to be broken. Its only concern is just to earn not too short time to take advantage of. F-22 Raptor or B-2 Spirit, one of the most STEALTHy thing mankind ever had, must be seen if poorly operated. Don't wanna mention that F-117 was shoot down in battle. So there's no valid concept of stealth in your criteria. You're saying for nothing. D'oh

Directional stealth can be nothing as much hard as you said. Just put some radiators behind your back and cold fuel tanks broadside, not to be seen by the enemy. It still will radiate heat. That's okay, the enemy would misread your amount of force. They need some remote sensor to detect your real heat signature. You made them to spend pennies, that's it. Way better than showing off your glowing radiator to them and say "HELLO I'M BLAHBLAH CLASS CRUSIER FROM THE BLAHBLAH FACTION HOW ARE YOU?"

Besides, you can dodge while showing your stealthy side to your enemy, thanks to the space being 3 dimensional. But I don't think that's even needed. If you have taken advantages from your stealth enough, you can ditch it. Submarines to super quiet not to be detected, but can dodge in full speed making a huge noise. That's what called tactical decision. And if you want to dodge, being stealthy so make them hard to point you out would help you enormously.

About your simplistic calculation, if things go in that way we don't need institutions of technology. How can you draw the line? In which accuracy? How can you evaluate it? How to encrypt and decrypt? What if the aggressor mimicking the data, called electronic warfare? How do you tell the decoy out of the real target? If you use omnidirectional antenna it's easy to be jammed. If you use directional laser comm you have to know where your sensors and laser batteries. All these engineering problems are the purpose of being stealthy. Distributed assets? Haha, tell them to real generals again. I do wonder why haven't they make every single fighters AWACS and be stealthy and can carry a company and can refuel.

Do you know that even stationary installment like fortress or castle tries its best not to be seen by its opponent, from the very start of human history, even thought that's just not possible by physics? War is not all-or-nothing game, it's just try-your-best-not-to-be-dead-before-your-enemy thing.

Once again, stop being nerd.

Edited August 19, 2018 by FennexFox

[0111narwhalz]

58 minutes ago, FennexFox said:

stop being nerd.

It's amusing that you come here, of all places, to tell people to not be nerds.

[FennexFox]

Just now, 0111narwhalz said:

It's amusing that you come here, of all places, to tell people to not be nerds.

You can't make a circular orbit if you go way too much with one direction

[weissel]

10 hours ago, FennexFox said:

I just want to remind you that even Gerald Ford class CVN, one of the most biggest ship mankind ever had, is still struggling to get STEALTH for its only partial fraction. Way easier target than a multi square kilometer cross section space warship megameters away. Now say that whatever stealth you have made is useless on the naval surface because of tidal trace, wave it faces,  and so much of blah blah, and say that again to the REAL admirals who spend tons of budget and manpower. Note that it doesn't want to be invisible, just to be harder to hit.

So we are playing WWII subs and destroyers in space?  That's a fine, comfortable metaphor we all (think) we understand.

Unfortunately, applying naval ships to the space environment is as apt as applying pike formation tactics to air carrier task force vs submarines battles.  It simply does not compute, the environment is simply too different.

 

First, you are still misunderstanding the difference between operational stealth and tactical stealth.  The aircraft attacking Pearl Harbour were not stealth craft --- they did not do tactical stealth: They were pretty easy to see and to hear.
They relied on not being hit by a) surprising the defence (which is why the second and third waves had much higher attrition) and b) being aircraft: much faster and much more manoeuvrable than, say, battleships or destroyers, making them hard to hit.  And c) of course also being much smaller than even destroyers.

The aircraft utilized stealth (operational stealth) by nobody knowing the carriers were even there --- the carrier force (again, not exactly stealthy vessels) kept away from common traffic routes, used absolute radio silence (including removing key parts of all senders and locking them away securely) and e.g. leaving their (normal) radio operators back in Japan to create traffic[1].

 

[1] Morse code operators have a distinct "hand", like a finger print.  Which means that of course the US knew the "hand" of at least all morse code operators of larger warships, and likely of every last one they could get hold of.  And so radio direction finding of the known hands of a warship in Japan would (usually) indicate that that warship would be in Japan.

 

10 hours ago, FennexFox said:

Directional stealth can be nothing as much hard as you said.

I did not say "hard".  I did say it means a lot more mass, mass which is always at a premium in spacecraft.  Mass that you do not use for weapons, armour, storages, ammunition, batteries, reactors, heat sinks, fuel, crew living space, sensors, missiles, specialists, an extra bathroom or even a cinema or arcade game hall.

But do read up on it, do the maths yourself if you need to and come back and tell us how to do it right and what that entails.

 

10 hours ago, FennexFox said:

Just put some radiators behind your back and cold fuel tanks broadside, not to be seen by the enemy. It still will radiate heat. That's okay, the enemy would misread your amount of force. They need some remote sensor to detect your real heat signature. You made them to spend pennies, that's it. Way better than showing off your glowing radiator to them and say "HELLO I'M BLAHBLAH CLASS CRUSIER FROM THE BLAHBLAH FACTION HOW ARE YOU?"

"Just put some radiators behind your back" ... just in front of or just behind the engines? And how many can you put there --- remember if the radiating sides can see each other, they will also soak up heat from each other.

The enemy will "misread your amount of force"?  Yes, they will be getting your exact tonnage the second you use your engine.  They know how fast your engine is spitting out matter (spectral line shift), what matter it is (spectral lines), how much matter it is (brightness), how much you accelerate radially (towards/away from any observer they have) and even with one observer they can track your perpendicular motion change.
Which means they know exactly what your mass is.  And what drive(s) you use.  And that is just you using your engine.  Which you will have to.
Now, yes, you could have various vessel types with the same mass and identical engine but different armour/weapons/stuff, but that is all you can do.

And to answer your next question:
http://www.projectrho.com/public_html/rocket/spacewardetect.php#nicollslaw

PS: how long, again, is your plume?

PPS: What "fuel" do you use that is liquid at 3K?

 

10 hours ago, FennexFox said:

Besides, you can dodge while showing your stealthy side to your enemy, thanks to the space being 3 dimensional. But I don't think that's even needed. If you have taken advantages from your stealth enough, you can ditch it. Submarines to super quiet not to be detected, but can dodge in full speed making a huge noise. That's what called tactical decision. And if you want to dodge, being stealthy so make them hard to point you out would help you enormously.

Which side would that be, considering that there will be sensors in about every direction everywhere?

And how do you, exactly, "ditch your stealth"?  No ditching, at best no longer using.

As to submarines: if you want quiet, you need a diesel-electric one.  Nuclear reactors need pumps and co.  Modern diesel-electric subs are quieter than the ocean that surrounds them, which has embarrassed and frustrated a number of US carrier task forces and their commanders as they tend to get into perfect torpedo attack positions and are only noticed when they surface there during the exercise.

Note that obviously nuclear subs can outrun (endurance) and outsprint (top speed) diesel-electric ones easily.  And of course a nuclear sub can be under water until food runs out; however AIP has allowed diesel-electric subs to stay under water for 3 weeks, including travelling from Europe to the US while staying submerged the whole time.

 

10 hours ago, FennexFox said:

And if you want to dodge, being stealthy so make them hard to point you out would help you enormously.

Sure it would.  A Harry-Potter-like cloak of invisibility would help enormously as well --- and is on the whole more likely.

Dodging means applying your engine.  Applying your engine --- well, let's just say that a single RCS thruster of the space shuttle is visible 15 million kilometres away.  So inside any kind of weapons range you'll be visible --- and that thing is way too weak to 'dodge' anything for your much larger vessel in combat.  The space shuttle main engines + SRBs is visible plain to Uranus at least.

So please show me how you dodge without uncovering your radiators and not showing your engine plume.  Even with just one single enemy and no other sensors in the universe, the only way to keep your plume hidden is dodging straight towards them.

 

10 hours ago, FennexFox said:

About your simplistic calculation, if things go in that way we don't need institutions of technology. How can you draw the line? In which accuracy? How can you evaluate it? How to encrypt and decrypt? What if the aggressor mimicking the data, called electronic warfare? How do you tell the decoy out of the real target? If you use omnidirectional antenna it's easy to be jammed. If you use directional laser comm you have to know where your sensors and laser batteries. All these engineering problems are the purpose of being stealthy.

Simplistic?  I gave you a minimum example.  In an universe where directional stealth worked well, even the smallest "coast guard cutter" would have dozens, if not hundreds, of sensor drones.  Never mind that sensor drones would be about everywhere.  Imagine an air defence not using any kind of RADAR, but solely relying on listening posts and range, speed and altitude guessing --- today, in a developed country.  That's how incompetent "not placing sensors everywhere" would be in that universe of yours.

"How can you draw the line?"  You really, really have to ask that?  I draw a line using a pencil and a ruler (or their electronic equivalents), like anybody else.If you ask how to get the position is even easier: vector maths, finding the closest distance between the 2 vector lines. Let me google that for you.  You then assume the "real" point is in the middle of the shortest distance. You set an error term from the length of the shortest distance, and then you get a point and a confidence by combining any number or sensor readings.

Accuracy?  See confidence above.

Evaluate: see above

Encrypt and decrypt?  Whatever your standard system is?  Not that you need to, really, the data is not of that much knowledge to the enemy.

Electronic warfare?  "YAY, the stealthy enemy is sending a strong signal and is no longer stealthy!  Just fire at the source and ready the anti-radiation missiles."  Also, cryptographic signatures.  Sort of hard to fake, without taking over the sensor sat itself ... for which you would have to become visible to the sensor net.

Decoy?  As soon as you burn your engine, you decoy better has the same mass (and engine) as you do, or it'll stop being a decoy.

Jamming?  See above: anti-radiation missile & co.

Yes, I assume we all know where our sensors are at any given moment.  Just like GPS.  Which they actually might double as, except for space, too.
Since they are everywhere, they also are a hazard to normal shipping if they don't know, but knowing where they are won't help the enemy to avoid them.  And if they die, that in itself is a serious alarm signal. And yes, they'll be connecting to each other and reporting.  With cryptographic signatures.

The price of stealth is a widespread early warning system you would want anyway?  That's like saying big gun battleships were the price the other side had to pay for armouring up their vessels of war (Ironclads, Merrimac, ...).

 

10 hours ago, FennexFox said:

Distributed assets? Haha, tell them to real generals again. I do wonder why haven't they make every single fighters AWACS and be stealthy and can carry a company and can refuel.

Real generals usually do not keep all their forces in one single block.  Unless they had only one single phalanx and no auxiliaries at all: no scouts, no cavalry, no skirmishers, no rear guard ... not even a supply train.
Real generals tend to keep their main fighting force together to avoid defeat in detail, but they very much rely on distributed assets for intelligence, scouting, detachments(!), garrison forces, forts well spread out to serve as observation posts, strong holds, supply dumps ... they are distributed.  In fact, they would not work centralized.

The reason we tend to not have AWACS stealth fighters is the same reason there won't be directional stealth space vessels of war.  They don't work in the real world.

 

10 hours ago, FennexFox said:

Do you know that even stationary installment like fortress or castle tries its best not to be seen by its opponent, from the very start of human history, even thought that's just not possible by physics?

I also do not know of the illustrious career of the Titanic, where it was sunk at the close of WWII in a mine field laid by the US while doing duty as a "luxury" hospital ship.
But I suspect that illustrious career of the Titanic is much closer to the truth than your claim of "trying to be invisible" fortresses and castles.  Could you tell me which one of these is trying to be "not seen":
photos of medieval fortresses (duckduckgo.com search engine)

 

10 hours ago, FennexFox said:

Once again, stop being nerd.

Some call true reports they don't like "fake news", so I wonder, do you call people inserting facts into your space combat fantasy "nerds"?

Or are you simply telling me not to be a stickler with physics and details?

 

9 hours ago, FennexFox said:

You can't make a circular orbit if you go way too much with one direction

Any orbit (in a sphere of influence system like KSP) repeats itself over and over and over and over again.  Just like stealth in space discussions, covering the same ground again and again.

Please, before you go and tell us about all the wonderfulness of your directed stealth system, do the maths and give us a sensible estimate what weight penalty and operational limits that causes.

 

Edited August 19, 2018 by weissel
Unfinished post.

[Vanamonde]

Discussion split from another thread. Please stop insulting each other about it. 

[tater]

This necro starts with my true statement that stealth not being a thing is entirely reasonable (in a science fiction context). It is 100% true.

This doesn't mean it is impossible to make detection less likely, stealth has a specific meaning. A stealth aircraft has a signature that is that of a bird. If your sig is distinguishable from a natural object, you're not a "stealth" target, you'd just a less visible target. reducing the ability to direct weapons is only a thing outside ranges where missing is impossible. Directed energy weapons are unlikely to miss out to whatever their max range is, because they can simply raster shots across the possible target cross section.

All that said, we can postulate directional radiators, etc, and that's fine, but you need to flesh out the specifics of the SF universe we're talking about.

Let's assume that for some reason warfare makes sense at all (a large, marginal assumption, IMO). Reducing signatures is possible via radiators tech, etc. There are none the less a few problems with this.

In such a situation, the combatants cannot maneuver without being detected, they only have stealth in the sense that they are visible maneuvering, the they coast. If the maneuvering is detected, then then Newton is doing the driving, and you need not detect them at any given moment, you know exactly where they are (within some cone of uncertainty). Regardless, the militaries in that situation would then have a powerful incentive to place detection systems in a halo around the star system such that any directed radiation is detectable. That is a cheap countermeasure, so it would happen. You're now directing radiation away from some specific enemy, but not from their detection system at large.

As I've said above, and in every other thread about this, any arguments need to specifically enumerate the sci fi universe and all the tech available within that universe or they don't mean much. Using current tech, any space battlefield is in Earth orbit, and the sats are literally visible from the ground. No stealth, we even track tiny sat debris. Any battlefield beyond Earth orbit must be predicated on some SF future where there is some reason for such a fight, with all the tech that requires.

1 hour ago, Vanamonde said:

Discussion split from another thread. Please stop insulting each other about it. 

No idea why this was moved from a thread about a game, with rules that directly relate to this very subject---and indeed the nature of stealth in that game is highly defined because it's about that particular SF setting--to the Science and Spaceflight thread, where it's literally meaningless as discussion, IMO. Every poster will now be talkiing past each other, with a specific SF world in mind, or none at all, but without realizing that it has to have a context...

It would be better to just delete this, and presumably ban conversation about the realism of any specific rules of Children of a Dead Earth from the thread about that game (for reasons that entirely escape me, since it seems like this particular stealth discussion very much belongs within the thread about that particular game universe).

[Cassel]

Stealth in space is possible, just read about asteroids that we can not detect because they are too small and move quite fast. The stealth satellite will be made of suitable materials, so it will be even harder to detect.
The orbit of such a satellite can run outside the Earth's low orbit and it can perform maneuvers beyond the moon. Is it enough to hide in front of observation devices on Earth and its orbit?
There are materials that allow you to hide tanks from infrared scanners, why hiding a more advanced satellite in space would be more difficult?
Can you defect ion drive?

I do not understand the need to wander in a short time throughout the entire solar system, what we want to observe, from hiding, is on Earth.

Edited August 19, 2018 by Cassel

[Bill Phil]

22 minutes ago, Cassel said:

Stealth in space is possible, just read about asteroids that we can not detect because they are too small and move quite fast. The stealth satellite will be made of suitable materials, so it will be even harder to detect.

Those asteroids are difficult to detect, yes. But that applies to us, at our current level of technology and number of telescopes. It's entirely reasonable for multiple space militaries to have massive, hundred meter or larger, telescopes hunting for thermal signatures. Scanning the entire sky can be done in a matter of hours with current technology.

But even then, spaceships emit more heat. Apophis (an asteroid) has a mean radius of roughly 185 meters. Solar irradiance is about 1361 W/m^2. It only receives 146 megawatts or so from the Sun. To be in thermal balance, it has to radiate this heat away. There are a number of equations for this, but we can basically say that it has to radiate away as much heat from the Sun as it gets, or it'll just get more and more energy from the Sun. Meanwhile, a single SSME has gigawatts of power, an appreciable amount of which is radiated as heat. And that's a chemical engine with an exhaust velocity of less than 5 km/s. You'd want something much more powerful to get around at any decent speed. In the Expanse, for example, they have stealth ships. Even though they have drives with massive plumes that are thousands of degrees Kelvin. No stealth is possible in that situation.

As for satellites, you could get away with stealth of some sort. But once a detector is within some range it'd be easy to see.

[Cassel]

24 minutes ago, Bill Phil said:

Those asteroids are difficult to detect, yes. But that applies to us, at our current level of technology and number of telescopes. It's entirely reasonable for multiple space militaries to have massive, hundred meter or larger, telescopes hunting for thermal signatures. Scanning the entire sky can be done in a matter of hours with current technology.
 

Hehe, like with everything, with 100,000 tanks you can conquer the planet, but is there a state that can afford such an expense? Stealth is to raise defense costs to such an extent that the opponent will not be able to lead a war.

Quote

But even then, spaceships emit more heat. Apophis (an asteroid) has a mean radius of roughly 185 meters. Solar irradiance is about 1361 W/m^2. It only receives 146 megawatts or so from the Sun. To be in thermal balance, it has to radiate this heat away. There are a number of equations for this, but we can basically say that it has to radiate away as much heat from the Sun as it gets, or it'll just get more and more energy from the Sun.

How does the Earth radiate heat?

Quote

Meanwhile, a single SSME has gigawatts of power, an appreciable amount of which is radiated as heat. And that's a chemical engine with an exhaust velocity of less than 5 km/s. You'd want something much more powerful to get around at any decent speed. In the Expanse, for example, they have stealth ships. Even though they have drives with massive plumes that are thousands of degrees Kelvin. No stealth is possible in that situation.

As for satellites, you could get away with stealth of some sort. But once a detector is within some range it'd be easy to see.

I'm writing a second time, why is this satellite have to fly far away? After all, everything we want to watch is on Earth, the only thing that is needed is minimal corrections with low power engines.

What about the ion drive, it also generates so much heat?

Edited August 19, 2018 by Cassel

[tater]

^^^^Because this thread is about nuclear powered spacecraft fighting wars all around the solar system, with humans living past Earth. Any other presumptions are off topic, which is why this should not have been split from the thread or came from.