I agree that it should not be hard to spot, but I think it would add to the game if you at least need to bring a 1-4 ton thermal sensor to spot them from normal "earth" solar system distances.
When it comes to wrecks it would be pretty cool for them to also not "pop up" but have to be detected through normal active sensors.
I have to disagree. There's discovering neat things, then there's missing neat things because you had no idea they were there.
A battle in a system you just explored, for example. On the one side, you see distant weapon flashes as the battle rages and ships exchange vollies. On the other you just get lag-lag-lag-oh a wreck-lag-lag-lag - and if wrecks aren't auto-detected then you don't even see that.
Wrecks likewise are fairly uncommon, neat things. Making them harder doesn't seem like it would add much. I suppose I could see maybe a small
chance for wrecks to show up as just lifeless ships under the same detection rules and such, but that also complicates combat as it becomes harder to tell if a ship you just shot is really dead or not. Maybe if it was an 'intact wreck' with a boosted chance of salvage?
Imagine if a wreck is indistinguishable to a powered down undamaged ship? Imagine the tension of having to close to very very near distance to be able to spot minimal thermal signatures added to for example life-support systems to be able to determine this.
Most of this damage is however transfered to the ship. At least for me I always assumed that a nuke does not actually impact but rather detonate some distance away meaning most of the energy is directed elsewhere (for example towards your sensors).
Much of the energy is still radiated away indurectly from things like swaths of hull being flashes to star-hot plasma and flashes of hard radiation as phenominal energy densities rip atoms apart enmass.
And there's the fact that modern tech is good enough to spot the space shuttle's engines firing from the orbit of Pluto.
If you
don't want to handwave things, Aurora sensors are either incredibly,
phenominally bad, or transnewtonian ships have some pretty major innate stealth characteristics.
I tend to go with the later, as more believable and in line with the ability to see every planet, moon, asteroid and comet in a system as you jump into it without having to conduct an in-depth survey. I also imagine that wrecked ships have been torn open and these stealth qualities lost.