I really like the sensor explanations there.
However, now break it down to at max 4 systems (plus the stealth tech which can be 20 for all I care), and make sure that every single one of them has a distinct strength and weakness, a use in game, and looks consistent within the games rules (faster than light signal travel, no 3d space, etc.

Block of text ahead...

Even more craziness.  Would make an absolutely awesome addition (alliteration FTW) to the game though.  Rather complex though. 

2.  EM signature and thermo-signature. . .  are, I'm afraid, one and the same in space.  Since there is no surrounding medium, the only way to get rid of heat is to radiate it away, in the form of EM radiation.  I know that accuracy isn't Auroras first concern (although the real scale stellar systems already top all other 4x games I know of), but it's kind of an itch every time I see the two. . .  Yes, I'm pedantic, feel free to ignore.

That said, we need the good ole' telescope back. 
Perhaps merge the sensors into a first principles system. 

Define the wavelength your sensor measures (radio, micro, infrared, visual, x-ray+)
 - You cannot see anything outside the range you define.  To make it simpler, just have those 5 instead of making players learn the scale of the EM spectrum
 - Deep Space Tracking should see into all ranges of course. 
Define energy sensitivity to a maximum of the background radiation / resolution
 - Bigger sensors have higher sensitivity approaching the background.  Since anything gives off at least a bit of energy from solar irradiance, you can see things further away with the radiation. 
 - Background radiation decreases as you go from radio to x-ray. 
Define resolution to the minimum arc angle you can differentiate. 
 - Affects distinguishing of contacts and so on. 

All ship systems, shields, engines, colonies.. everything including planets and the suns give out radiation. 
Active sensors (radar) and communication relays give off radio waves
 - As well as any electronic ship system that is active (cargo holds, fuel tanks and armour don't give that off unless actively loading/unloading)
 - Populations give off alot of this due to high emissions of installations
Microwaves are given off by high energy systems and obviously the microwave weapon. 
 - Firing/charging weapons give this out, microwave weapons give out alot
 - The sun gives this off liberally as well
X-ray+ are shields, jumpdrives and jumpgates + missile detonations.  And scattered x-rays from lasers.  (see active sensors below)
Infra-red would be the based on the temperature of the ship. 
 - Engines and running reactors (ie. charging weapons) give out alot of this. 
 - Crew quarters also give this out.  Black body radiation equation vs race optimum living temperature... ?
 - The sun sheds tons of it. 
 - Planets give off a lot, depending on their temperature. 
Visual is the tricky one.  Active engines give this out.  The sun gives off alot as well.  Planets give it off depending on irradiation strength vs planetary albedo divided by greenhouse factor. 

Each system would have an emission spectrum and power of each wavelength.  The total of your task group is added and fades via inverse square law.  If it goes below the background radiation, you can't be seen at that distance. 
 - even if it fades below background, multiple overlapping signatures close together could add together to produce something detectable.  IE. things in one task group or on a planet/asteroid simply add their signatures.  Task groups might need a distance between ships however, to detect individual ships when you get close enough.  Perhaps resolution below cross-section size of a ship will allow your sensors to pull out the individual contacts of ships around that size. 
 - Cloaking simply reduces your power output by stated percentage.  Absorption paint could absorb more power against actives and lower reflection. 

Resolution of your sensor depends on your sensor size / wavelength. 
The resolution of your sensor means that any ships less than that angle apart merge into one contact.  The power output of that contact is added together. 

When sensors find a contact, all you're given is power output detected and distance with errors. (size of the contact depends on resolution)  Displayed on the system map with error bars for more win. 
 +detail: Sensors in separate positions could combine readings to increase resolution, detected power and give an autocalculated estimate of the actual power output.  Reduces errors on the distance estimate on the angle between the two most separate sensors and the number of sensors. 
 ++detail: System survey.  When you first enter a system, you don't see all the system bodies immediately.  You have to detect them via sensors.  Luckily, bodies tend to be relatively big and shine from the sun's output.  If you have a good telescope, you should see everything except for far away comets and oort cloud objects.  The defaults sensors on every ship should be able to see the sun regardless unless you're ridiculously far away. 


Active sensors.  Well, these things are essentially torchlights. 
You shoot a pulse (either directed at a contact or in all directions) of a wavelength that your antenna supports.  The power depends on the size of the antenna. 
 - Higher wavelengths require more power to run.  And hence are generally longer ranged but suck more fuel and are more obvious. 
The power of this pulse drops via inverse square. 
When active, things receive power from the sensor.  Depending on the cross-section of the object and it's albedo to that wavelength (special cloak paint?), it reflects some of it.  This increases the power shed by the object... which passive sensors pick up. 
A directed pulse can be shot at an object.  Radiowaves need an antenna.  Microwaves use that weapon.  Higher wavelengths use the lasers.  (non-combat lasers XD)
 - Since an active sensor sheds power further than it reflects off objects, active sensors show up very obviously.  So, if you pick up something on passives, you might want to turn on active sensors and only fire a directed pulse at the contact to avoid giving away your position that a general broadcast would.  Either that or get the boys back home on the so obvious colony to do the active sensor broadcast for your ships. 
 - Lasers are directed pulse only.  And require you to hit (albeit at increased accuracy due to defocusing)

Lasers.  When they hit something, it's emission on that wavelength increases for one tick. 
If they deal damage beyond shields, there's a residual increased infrared signature for a minute or two. 
Lasers firing directed pulse don't deal damage obviously. 

Missiles explode to give off a very high emission of all wavelengths.  Not enough to reflect though (and to save computational power)

The sun is a giant active sensor.  With regards to system survey, all system bodies receive power from the sun and reflect it dependent on albedo.  ^^  Consistency. 


Fire Controls.  You don't need an active sensor to fire a missile.  It's just recommended.  You fire a missile at a contact.  Distance error affects accuracy, not tracking speed.  Missiles still need to catch their targets though and their equation isn't affected. 
Missiles will thus almost certainly require a sensor. 

ECMs.  You can beam power towards a contact to increase your power rating for that sensor alone or just broadcast it (requires bigger ECM for same power)
ECMs can emit from any wavelength you like but can only make your power output increase. 
Which makes you appear as different than you normally are. (is that one big ship or many small ones or just one small one with an ECM?)
You could also orbit a planet while having everything off.  You'd appear very similar to a rather metallic moonlet with an unusually high thermal rating (crew quarters can't be turned off)
ECMs in general could be tuned to give off any emission profile you want.  Good cloaking tech and good ECMs could make you look like asteroid chunks if you're big enough. 
 - A new engine tech could be created.  Similar to a low tech engine in power, but emission spectrum is similar to a comet tail.  XD you can see where I'm going with this. 

Chaff: The real ECM.  You shoot a missile out from your ship which contains an ECM to look like a ship's emission profile.  This creates more ship-like contacts if they have the resolution to see you (decoys) or increases the effective size of your contact if they don't (higher inaccuracy + decoys). 
If they light it up with a directed pulse, they'll find out pretty quick that it doesn't have the expected cross-section.  Which a good ECM combined with passive sensors could make it change ECM profile when that happens to mimic a larger cross-section. 
If they hit with a weapon laser however, your cover's blown. 


Would make detection of wrecks more difficult since you need to active sensor sweep once the body has cooled down and gives off almost nothing.  And it really just looks like a small asteroid until you look at it's emission profile and find it's insanely reflective. 

3.  Installed installations.  It is a bit irritating how everything in the Aurora universe seems to be portable, even a factory that was in use for the last few decades.  It might be a nice Idea that would add even more need for planning to put installations into a "storage" after being constructed, where they don't have any benefits.  From there, they could either be transported away or installed on the planet.  Once installed on whatever planet, they bring their benefits, but cannot be removed again. 

Sounds simple. 
Installations don't work in storage but can be picked up like any another cargo. 
Installations can freely convert between storage and installed modes.  It just takes time and some manpower.  (construction power?)

This might be a question you hear often and probably get bored of, so I hope you'll forgive me asking: why not C++?

'cuz I told him C# was a much more powerful, next-generation language that he should take a look at, and he seems to have believed me :-)  Try it - you'll like it :-)

ahhh. . .  so EM in aurora majorly serves the purpose of picking up em emissions in the very low em spectrum.  It actually would make sense to have different sensors for that.

Not quite.  EM = "the same stuff the active FTL sensors emit" in Aurora language, i.e. it's poorly named.

John

the calculations required to be in the right place at the right time are considerable.

I know. . .  I'm an Orbiter player.    So yeah, I didn't expect that one to find any real consideration, since I know pretty well what's involved, especially if you'd take realistic isp and thrust values.  although, for the purposes of aurora the model could be simplified to consider spherical cows like constant mass and teh powerfull torchdrives(TM) (which it more or less already has).  But yes, rewriting the whole AI to conform to the new environment would be a somewhat monumental task, and I perfectly understand how that is not what you're after.

At the moment I am learning Visual C# 2010 and considering a Newtonian combat game.

This might be a question you hear often and probably get bored of, so I hope you'll forgive me asking: why not C++?

The problem is I like 4x games involving combat more than stand-alone combat games, mainly because 4x games provide a reason for the combat to take place.

I don't consider that a problem, since I wholeheartedly agree with your sentiments.  The only thing better than a 4x game could (imho) be an RPG with a 4x game running in the background, but there's no such thing yet. . . 

So I think I will end up writing Aurora II at some point,

A most exciting prospect to be sure!

EM in Aurora is analogous to using ESM to detect radar signals while thermal is analogous to infrared detection systems.

ahhh. . .  so EM in aurora majorly serves the purpose of picking up em emissions in the very low em spectrum.  It actually would make sense to have different sensors for that.

This has evolved due to user-demand.

Interesting.  While I'm progressing through the game I start to see how it might have evolved, with planets running dry on resources and the industrial capacity to rebuild all those mines being used for other things, but making it optional (like maintenance failures) might have been a good move.

It would be too fundamental a change for Aurora though.

since I don't know the architecture of Aurora, I take your word for it.  I wouldn't have expected it to be a very fundamental change.

I found Aurora about a week ago, registered on the forum, and since then waited for a mail by the Admin that I was aproved, until I finally tried to login today just to see what would happen, just to find out that obviously I have been aproved without getting a mail. . .

Same for me... Something should be done on forum registration, I desperately waiting for a mail that never arrived.

You should post things like this in the current official suggestions thread. Steve uses those threads as a sort of filing cabinet so he doesn't have to remember what all the individual threads say. A thread like this is liable to fall off the first page and be forgotten.

In regards to your suggestions:

1. Building a Newtonian flight model is relatively simple compared to building guidance algorithms that would let ships actually function in such an environment. It's just not worth the effort, to say nothing of how complicated combat would get.

2. I'm not sure EM sensors actually have anything to do with electromagnetism, actually. They pick up shield emissions, grav pulse active sensor emissions, and populations. Populations are the only one of these that would obviously have a big electromagnetic signature.