How do ships see?

[kafka47]

Now, there are all sorts of rules regarding sensors and the measurements that they take. Active EMS & Passive EMS all can be fooled by ECM. Densometers would only work if there was a position willing to feed back the information gathered.

So, IYTU or the OTU (as a matter of fact), what do ships "see"?

Some suggestions:

a)A full fledged holographic reproduction of the ship that is before them because the computer has guesstimated what ship is out there in the black based upon all variables it coorelates.

b) A Battlestar Galatica SADAR (original series) or DRADIS (reimagined series) reading which shows just blips like an early video game based upon transponder readings that would give approximate vectors from extrapolation.

c) Technical readouts that would ressemble the Matrix coding that appeared at the beginning of each film and a Sensor tech to interpet.

d) Like above but done with an audio signature rather than simply visual, like what submarines now face.

e) Ships are essentially blind until a sensor bounce back can an active reading.

f) something not mentioned above (please specify)

 

[Valarian]

In my opinion, sensors would act in a similar way to the submarine scenario, but the readings would be from energy signature and gravitational displacement rather than audio signature. Passive sensors would read the ambient energy and try to separate ships from the background energy readings. Active sensors would emit energy and read the returned signature.

EM, Neutrino and gravity sensor readings would be collated in to a display for the sensor tech to interpret. Whether this display would be the Galactica SADAR style or the submarine waterfall style could be dependent on cultural background. I like to think in terms of air traffic control radar. Ships with active transponders (most civilian ships) would be added to the display with their transponder code. Ships with no active transponder would be added only if detected and would display no code next to the icon representing their position.

 

[Andrew Boulton]

Basically (a), but lower TL/quality may be more like (b).

Civilian ships will generally base their display on just the transponder data, whereas military ones will use the actual sensor readings.

 

[Zob10701]

Forgive my igonorance, but what is SADAR?

 

[Black Globe Generator]

Originally posted by TheVamp:
Forgive my igonorance, but what is SADAR?

A Passover dinner.

 

[kafka47]

Originally posted by Andrew Boulton:
Basically (a), but lower TL/quality may be more like (b).

Civilian ships will generally base their display on just the transponder data, whereas military ones will use the actual sensor readings.

You partially answered the next part. What would PC ships have as part of their array.

What would be Megacorp liners have, akin to military or more like civilian?

Please treat these as follow-up questions not replacement for the originals.

 

[atpollard]

Originally posted by Valarian:
Passive sensors would read the ambient energy and try to separate ships from the background energy readings.

This is a very hard thing to do. A ship is so small and the ranges are so great that even a narrow field of view would require a very large grid of molecular scale detectors to achieve the resolution needed to detect a ship at Traveller detection ranges. Passive EM detection at AU distances would require either a giant detector or extraordinary luck. I tried running the math once and decided that "handwavium" worked a lot better than science.

I think active sensors would be better, the background should be a lot weaker than your reflected "ping". The power of your active beam then becomes the biggest factor in detection ranges.

 

[Anthony]

Originally posted by atpollard:
This is a very hard thing to do.

Not really. A 1 meter telescope, in space, can reasonably spot a magnitude-22 object in about ten seconds, using electronics available today. Using a conventional telescope it would take on the order of a day to scan the entire sky (and a pretty competent computer, though again, something you could get today), but on a bare hull (ignoring any heat output) that's a battlecruiser at 1 AU or a fighter at 50 light-seconds. At 1/10 that range you could use 100-200mm refracting lens and scan the entire sky every ten minutes or so. You can reduce visible light detection range a factor of ten or so with extremely black hulls, but it won't make much difference, because black hulls simply reradiate the sunlight in the infrared, and IR sensors aren't that much worse than visible light sensors. Worse, magnitude 22 at 1 AU is only around 10 MW anyway, so waste heat from the power plant will normally be visible at multiple AU for even very small ships.

 

[ElHombre]

Stealth in space doesn't work. The details can be found here but the short version is that, unlike water, space doesn't have anything to hide in. If a ship is powered (and if it has a crew, it needs to be unless they want to freeze to death) it generates a large enough heat signature to be measured across a star system. Using the drives is lighting a bonfire in a dark closet.

Ships that are moving automatically give away their mass. From this, it's easy for a ship's computer to tell what's on the way. So surprise is out. But you would need an active EMS system to give good targeting data.

 

[Ran Targas]

Originally posted by ElHombre:
Stealth in space doesn't work.

This statement is fine except it assumes a great deal on the part of the observer. The observer would a) have to be capable of "scanning" every square arc-second of view around their post with b) sufficiently advanced instrumentation to differentiate an approaching "stealth" starship from background radiation. As a) and b) can be physically difficult, technologically challenging, or even just plain cost prohibitive, there will always be ways to slip by undetected. If the observer isn't paying attention, even a black paint job and running silent might be effective.

And I wouldn't take anything posted on any fanboy's website as the definitive work on space based stealth technology. By the time humans are smart enough to figure out jump drives, I'm sure even smarter humans will be working on stealthing out a Type S.

 

[Ptah]

Originally posted by Ran Targas:
</font><blockquote>quote:</font><hr />Originally posted by ElHombre:
Stealth in space doesn't work.

This statement is fine except it assumes a great deal on the part of the observer. The observer would a) have to be capable of "scanning" every square arc-second of view around their post with b) sufficiently advanced instrumentation to differentiate an approaching "stealth" starship from background radiation. As a) and b) can be physically difficult, technologically challenging, or even just plain cost prohibitive, there will always be ways to slip by undetected. If the observer isn't paying attention, even a black paint job and running silent might be effective.

And I wouldn't take anything posted on any fanboy's website as the definitive work on space based stealth technology. By the time humans are smart enough to figure out jump drives, I'm sure even smarter humans will be working on stealthing out a Type S. </font>[/QUOTE]QFT, "project rho" should not be taken as gospel. The guy is an artist with a very cool site who appears to have searched the internet and cut and pasted things to his liking, as well as scanning and posting the covers of many a sci-fi novel.
He's not an expert as he himself says here
and shouldn't be taken as such. [/rant]

 

[ElHombre]

Originally posted by Ran Targas:
This statement is fine except it assumes a great deal on the part of the observer. The observer would a) have to be capable of "scanning" every square arc-second of view around their post with b) sufficiently advanced instrumentation to differentiate an approaching "stealth" starship from background radiation. As a) and b) can be physically difficult, technologically challenging, or even just plain cost prohibitive, there will always be ways to slip by undetected. If the observer isn't paying attention, even a black paint job and running silent might be effective.

Suit yourself, but space is, what, a few degrees above absolute zero? A ship's habitable section has to be kept around 300K. Then there's the heat generated by the power plant. It's not going to take much for a typical Traveller ship sensor equipment to notice. Space is big, cold, and empty. There's no ocean of heat-absobant material to conceal a ship and anyone would have plenty of time to notice a lighthouse AUs away.

In game terms, this means that you don't really have to worry about sensor rules (and one less set of rules to deal with is a good thing, IMO ). This also means that ships don't have to worry about the color of their ship affecting their stealth rating. Put a paint job on that thing that would make a Vargr blush. Imperial Marines use a specific shade of red to impress folks? Imagine the looks of awe when a BatRon arrives in orbit the same color!

As far as what sensors can see, if the other ship's signature is in your ship's database, you'll be able to recognize it. If you want to hide a ship, I can only think of a couple of different ways. One is to use the ship as a sub. SDBs already hide underwater, why not a corsair? Of course, IMTU, ships have to be specifically built to travel underwater. The other way would use Ancient technology (i.e.: handwavium). Instead of radiating a ship's heat into space, you have to store it in a portable universe and those are something that Ancient ships carried. (come to think of it, the Tardis would make an excellent stealth ship)

 

[atpollard]

The trick is not "seeing" a ship in space. You are quite correct that it's heat signature will rival that of most stars.

I see the problem as one of resolution. How do you detect the important specs of heat and ignore the unimportant specs of heat. At the most basic mechanical level, the sensor will be reduced to a matrix of detectors and each detector will receive all of the light/heat/whatever from a specific cone of space (some fractional seconds of arc). This sensor will add all of the energy it recieves and report it at a single pixel of data. Combining all of the pixels give you an image of the space around you. The heat of your ship will be averaged with the background stars and the empty space between the stars to give one numeric value for the pixel. At 1 parsec, your Scout Ship will occupy such a small fraction of the detection area of that 1 sensor dot that it will not be recorded as a significant portion of the energy being detected … so you cannot spot a scout ship at in a star system 1 parsec away (an extreme example to illustrate the point). On the other hand, if that same scout ship were only 100 meters away it would dominate all of the sensor pixels and you could see nothing but the scout ship (another extreme example). At some distance between these two extremes, the Scout ship will occupy the entire field of view of exactly 1 sensor pixel – this is the maximum detection range for that ship and that sensor. Farther away and the ship will be averaged with it’s background. Closer and it will begin to be detected in greater resolution.

Do not forget that the “background” is not at a nice uniform temperature and brightness but is composed of vast cold, dark areas and many small hot, bright objects. The difficulty that I see, is that each planet or bright star or star cluster has the potential to be detected by one or more sensor pixels. How do you distinguish between a typical planet at the range where it occupies one pixel and a ship at the range where its energy averaged with the background energy have the same energy on the sensor pixel as the planet. How do you see the enemy tree in the vast forest of background trees?

To complicate the task, your telescope/sensor is bouncing along in the back of a pickup truck while you are scanning the sky. As I stated earlier, the math gets ugly very quickly and I didn’t care about the answer enough to slug it out.

Detection is not impossible, but it is not as simple as “you can see any ship as far away as the oort cloud with a hand-held detector pointed out the window of your ship because nothing hides in space”.

Those are my thoughts on the subject.

 

[ElHombre]

How do you distinguish between a typical planet at the range where it occupies one pixel and a ship at the range where its energy averaged with the background energy have the same energy on the sensor pixel as the planet. How do you see the enemy tree in the vast forest of background trees?

Easy enough: You look for the tree that's moving. A star will stay put. A planet will be moving in a predictable orbit (assuming that the system is charted, which is a pretty good guess. the Scouts must have been doing something for the past thousand years). A ship will be a) moving against the steady background of stars, and b) changing its orbital path by using its M-drive (something a planet or asteroid should not be doing unless you have an affinity for Death Stars IYTU). Given the distances involved the sensors will have plenty of time to figure out which is which. Even vacuum-tube computers will have enough time to figure out the data.

The main point I'm driving at is that players spend less time dealing with sensor rules and more time deciding what to do about the Zho Shiiva which has changed its course for an intercept with the players. Do they talk, run, or fight? Which is what the players really want to do anyway.

 

[aramis]

Just remember: Detection is pretty easy, relatively speaking.

Identification is a whole 'nother matter.

ID requires enough data to get either distinctive EM emissions, or to get a "visual" image.

 

[GypsyComet]

Another thing to remember is that space is quite a bit "brighter" than most of us bottom-of-an-atmosphere dwellers realize. Even a night sky far from cities doesn't give an observer the whole picture.

And MT's over the top examples notwithstanding, how many penny-pinching merchants are going to spring for Survey-grade sensor suites? Most will not, and are far more likely to have a fairly simple ranged-but-directional passive array and broad-but-local active array. In other words, a navigational array and collision-avoidance radar.

 

[SGavorsky]

I think there are two different discussions going on here.

The first concerns the mechanics of seeing--sensors, transponders, etc. I'm on the side of "it's hard to hide in space"--with the notable point that IMTU normally questions of detection don't happen in open space but the cluttered confines of systems where planets, asteroids, other ships, satellites, and transmissions of all sorts form the local environment. It would seem to me that in this context the submarine analogy might be somewhat more accurate: there are environmental factors that can hamper detection if the target vessel is working to use these factors to its advantage.

Also, has anyone played with the "orbiting sensor platform" model for military ships, where co-travelling orbiting satellites might give fuller data (for instance, a true triangulation)?

The second issue is how this sensor data is presented to the crew in a usable format. I agree with the posters who argue for a dual-format for civilian/military ships. Civilian ships could use a transponder-based display that looks similar to modern air-traffic control stations, supplemented by occasional active sensor sweeps (maybe taking an hour to scan?) to "map" local space.

Military vessels might use more sophisticated systems that use technical readouts like the "waterfall" systems that give much finer data. With trained personnel to interpret the data, this becomes a more viable option. I still think, however, that "composite" displays that summarize the information for command officers--similar to the DRADIS on the new Galactica--would exist as well (although, given the time-scale of Traveller combat, I can see the argument this might not be necessary).

 

[SGavorsky]

Originally posted by TheVamp:
Forgive my igonorance, but what is SADAR?

I think they mean the sensor displays seen on the original Battlestar Galactica series.

My Google-Fu is failing me this morning, so no images. But the readout looked something like this:

[EDIT: Okay--my image totally didn't work. Basically, horizontal depiction with vertical range bands with Cylon Raiders (triangles) on the left, Galactica (triangle) on the right.]

It just struck me--this is pretty much the good 'ole Traveller range-band system.

 

[Anthony]

Originally posted by GypsyComet:
Another thing to remember is that space is quite a bit "brighter" than most of us bottom-of-an-atmosphere dwellers realize. Even a night sky far from cities doesn't give an observer the whole picture.

Roughly magnitude 22 per square arcsecond. That works out to a camera requiring about 13 megapixels per square degree, or a total of 500 gigapixels for the entire sky, assuming you scan it all at once, which you probably won't. It's an interesting data processing issue, but doable with today's computers. Reduce detection range by a factor of 10 and you can do it with a total of 5 gigapixels for the entire sky, plus a cluster of lenses; the whole system would fit within a dton, along with a tracking scope with probably thirty times the range. That's within the budget of a typical merchant; hell, it's probably what a mod-1 computer is.

 

[atpollard]

Originally posted by Anthony:
Roughly magnitude 22 per square arcsecond. That works out to a camera requiring about 13 megapixels per square degree, or a total of 500 gigapixels for the entire sky, assuming you scan it all at once, which you probably won't. It's an interesting data processing issue, but doable with today's computers. Reduce detection range by a factor of 10 and you can do it with a total of 5 gigapixels for the entire sky, plus a cluster of lenses; the whole system would fit within a dton, along with a tracking scope with probably thirty times the range. That's within the budget of a typical merchant; hell, it's probably what a mod-1 computer is.

No argument on your analysis, it sounds about right to me. Three questions:

First. Do you know what the range is that the sunlight reflected off a 300 degree K scout ship averaged with the background will be magnitude 44 per arc second? (the scout ship is twice as bright as the average sky).

Second. Have you considered that this computer/sensor problem needs to be solved in real time? If my ship is being shot at by another ship at a range of 100,000 kilometers, I may want to target the incoming missiles with my laser. I cannot abort a 10 minute scan because my ship performed evasive maneuvers and start a second scan with the sensors if I want to target the missile. We are searching for moving dots of light from a telescope that is doing barrel rolls on the back of a starship. This is not a job for a 2006 dell laptop with a dual core processor, and this is certainly not a job for Univac. I think multi-dTon starship computers need every bit of that space.

Third. If we use hardware to detect the moving object by comparing two images taken 1/10 of a second apart (an impressive exposure time) and only report the changes to the ship computer (to filter out stationary background objects) – then how fast will a ship need to travel (perpendicular to the field of view) at a distance of 900,000 km (maximum tracking range) to travel 1 arcsecond and be detected as “moving” by this 500 gigapixel detector.

Detection of a bright moving object by a fixed telescope comparing exposures made at 1 day intervals is easy, it would indeed be almost impossible to hide from such a detector. When you attempt to mount this scope to a spinning object and track missiles in real time, the problem becomes a lot harder. I would personally like to know what could be built TODAY using non-military technology and an unlimited budget. Mounted to a moving space shuttle, how far away could you detect another shuttle on a transfer orbit (no engines firing, but life support at normal levels). Is the range closer to kilometers or AUs or hundreds of AUs? Are CT sensors weaker than real life or “handwavuim” more advanced than real life?