T4 Only: Some people say no stealth in space, a discussion.

[Marcatlas]

What if he is walking away and his body is between you and the torch?
What if the plain extends in 360 degrees around you and he is EAST of your hill and you are looking NW?

The point being made that you so quickly rejected is that DETECTION is not 100% perfect or automatic.

Certainly If a ship is in low orbital range and behind a planet in relation to the sensor then it is blocked. But that is NOT a "flat plain" as I argued. That's called moving the goal post in an argument. Passive sensors that would be employed would scan ALL directions in space otherwise they would not be that useful. The point being, yes as I described, the "torch" would automatically be detected. It's science.

 

[atpollard]

The point being, yes as I described, the "torch" would automatically be detected. It's science.

Gideon proved otherwise. [fyi: Judges 7 for the story]

 

[Marcatlas]

Gideon proved otherwise. [fyi: Judges 7 for the story]

I know the story

But the variable is really how long does it take to spot the ship. That depends on distance and TL of the sensors. From minutes to many hours

 

[Spinward Flow]

But the variable is really how long does it take to spot the ship. That depends on distance and TL of the sensors. From minutes to many hours

Those differences in time can "make or break" an encounter opportunity, let alone a rendezvous for a matching velocity intercept attempt.
From such differential performances do things like Blockade Running emerge ...

 

[Dragoner]

Right. If you are standing on a hill overlooking a pitch dark plain at night and someone 5 miles away is carrying a torch, it is illogical to assume that you won't see it.

The fact is that it happens all the time with detection systems, even the mark 1 eyeball.

 

[Spartan159]

The fact is that it happens all the time with detection systems, even the mark 1 eyeball.

So, being able to look around in a flat plane vs. searching a 3 dimensional sphere does not narrow down the search, not to mention would that 5 mile away torch possibly blend into a background of stars?

 

[mike wightman]

Here are the parameters from LBB2 81, with some edits for clarity

Starship combat uses the following scale for movement and combat resolution:
1. Time: Each game turn represents 1,000 seconds. ~17 mins
2. Space: A playing surface is required, representing space as a two-dimensional
surface at the scale of 1 :100,000,000; one millimetre equals 100 kilometres. Three
meters equal one light-second. Planetary template disks may be produced to show.
the presence of worlds and the effects of gravity.

Space is big. Now for detection

Ordinary or commercial starships can detect other ships out to a range of about
one-half light-second; about 1,500 millimeters or 1.5 metres. Military and scout starships have
detection ranges out to two light-seconds; 6,000 mm or 6 meters.
Ships which are maintaining complete silence cannot be detected at distances of
greater than half detection range; ships in orbit around a world and also maintaining
complete silence cannot be detected at distances greater than one-eighth detection
range. Planetary masses and stars will completely conceal a ship from detection.
Tracking: Once a vessel has been detected, it can be tracked by anyone up to
three light-seconds (about 9,000 mm, or 9 meters).

 

[Marcatlas]

The fact is that it happens all the time with detection systems, even the mark 1 eyeball.

Nope. It doesn't. Unless one were actually blind.

What we have here is Nicolls Law in play; https://projectrho.com/public_html/rocket/spacewardetect.php#nicollslaw
and Happyroachs Corollary to Nicolls Law. (see same link)

 

[Dragoner]

Nope. It doesn't. Unless one were actually blind.

What we have here is Nicolls Law in play; https://projectrho.com/public_html/rocket/spacewardetect.php#nicollslaw
and Happyroachs Corollary to Nicolls Law. (see same link)

Yes it does.

 

[Dragoner]

So, being able to look around in a flat plane vs. searching a 3 dimensional sphere does not narrow down the search, not to mention would that 5 mile away torch possibly blend into a background of stars?

You could be asleep, etc.

 

[Marcatlas]

You could be asleep, etc.

Yes, sensors go to sleep.

Yes it does.

Nicolls Law in play

 

[Dragoner]

Yes, sensors go to sleep.

Nicolls Law in play

So? No system is perfect, that is life.

 

[Marcatlas]

So? No system is perfect, that is life.

 

[Spinward Flow]

What we have here is Nicolls Law in play; https://projectrho.com/public_html/rocket/spacewardetect.php#nicollslaw
and Happyroachs Corollary to Nicolls Law. (see same link)

Hmmm ... interesting stuff if you keep reading long enough ...

A full spherical sky search is 41,000 square degrees. A wide angle lens will cover about 100 square degrees (a typical SLR personal camera is about 1 square degree); you'll want overlap, so call it 480 exposures for a full sky search, with each exposure taking about 350 megapixels.

Estimated exposure time is about 30 seconds per 100 square degrees of sky looking for a magnitude 12 object (which is roughly what the drive I spec'd out earlier would be). So, 480 / 2 is 240 minutes, or about 4 HOURS for a complete sky survey. This will require signal processing of about 150 gigapizels per two hours, and take a terabyte of storage per sweep.

~4 hours per COMPLETE 360º by 360º spherical sweep.
Not instantaneous.
About 4 hours.

Will your craft have changed position (at all) during those 4 hours?
If so, that's going to "skew" the sensor swept volume you can observe, such that you're not observing a "sphere" of space per se, but more like some kind of "corkscrew shape" that's almost but not quite "spherical-ish" (kinda sorta, but not really) when you plot both space AND time.

Imagine a spinning radar emitter that takes 4 hours to make a single "full circle" sweep, rather than spinning multiple times per minute.

That's going to leave ... gaps ... in sensor scan coverage for detections, because any sensor in orbit (around a star, around a planet, around a moon) is, by definition, in motion. Being able to scan the entire volume more quickly (and process the resultant data more quickly) will reduce the resultant "gaps" in the sensor sweeps, but an assumption of continuous real time omni-directional detection with total and perfect accuracy at all times without failure or need to roll anything would seem to be a much larger "leap of faith" as an argument.

Now, being able to intentionally "point" a sensor sweep in a specific vector to get more detailed "what is that?" scan will undoubtedly be relatively swift ... but that depends on KNOWING WHERE TO LOOK first ... in addition to being the difference between active and passive sensor sweeping.

 

[mike wightman]

So build a few more sensors stations - the data you quoted is for one station.

Fourteen stations - one full sensor sweep per space combat turn.

Now how many sensors can you fit on the hull of a ship considering the size of the sensor chip itself

 

[Dragoner]

Being able to scan the entire volume more quickly (and process the resultant data more quickly) will reduce the resultant "gaps" in the sensor sweeps, but an assumption of continuous real time omni-directional detection with total and perfect accuracy at all times without failure or need to roll anything would seem to be a much larger "leap of faith" as an argument.

Exactly. Only when one wants to eliminate operator errors, equipment failures, give unlimited time, etc. to the point where it is unrealistic. This is where the quote from Star Trek is relevant: "It is possible to make no mistakes and still lose, that is life." Same goes for detection regimes. Real life shows things can go wrong all the time. Just because something can be detected, does not mean it will be detected. This does not even go into tactical situations, such as military deception, such as misdirecting attention away from somewhere, which is standard procedure in operations as well.

 

[Marcatlas]

Just because something can be detected, does not mean it will be detected.

In this case, yes it does because the amount of time spent in plain view is VERY long. So unless sensors shut down for MANY hours or days at a time you WILL be detected

 

[kilemall]

Here are the parameters from LBB2 81, with some edits for clarity

Space is big. Now for detection

You’re skipping over the doggo rules, which expressly covers a stealth mechanic. A ship lying doggo is only detected at 1/8 the above stated civilian or military ranges.

Doggo is not defined but my definition is no emissions, maneuver or weapons fire and power plant tuned to life support only or batteries.

 

[mike wightman]

I have quoted the entire text from CT LBB2 81 Detection section, including the 1/8th which is even in bold text.

I did so in order that people could base their handwavium on the rules as written

Ships which are maintaining complete silence cannot be detected at distances of
greater than half detection range; ships in orbit around a world and also maintaining
complete silence cannot be detected at distances greater than one-eighth detection
range.

I take "maintaining complete silence" to mean no transponder, no comms, no active sensors, no weapon locks.

So detection range becomes a quarter of a light second for a civilian sensor and one light second for military

These are passive sensors.

How about active ie weapon locks?

A laser can fire out to 250,000km, it can hit targets from 250,000 out to 500,000km with a DM of -2, and targets beyond 500,000km at -5 which implies the active sensor lock ranges for weapon fire and thus the range for active sensor sweeps.
Since sensor range maxes out at 900,000km that appears to be the longest range for an active sweep also.

 

[kilemall]

Ok missed the doggo section, apologies.

The computer rule for detection I have is simple- model # x 100000 km, bis counts as .5. Works out pretty well as Model 1/bis matches civilian and Model 6 is military.

Model 9 of course works out to 900000 but that’s ok, I have maintain tracking pegged to TL x 100000. Range of weapons is pegged to their battery strength, so turret and bay is 900000 km anyway, just the missiles and spinal weapons can reach further.