Space and Sensor information

[avi.hecht]

From what I played in CT and read in T20 the whole sensor/combat interaction seems to be over simplified to non-existent. Is it any better in the other incarnations of Traveller?

Detection (Passive/Active) EW and IC2 play a great role in the modern navel battle and could change the shape of the whole battle field. The current Traveller 'image' of ships of the line 'punching' through the enemy lines of combat feels more like a Napoleonic navel scene and not a modern fleet action.
I would imagine that navel warfare will look more like submarine warfare – but to really 'test' that we need a good model…

PS I have found in the past an article that discusses this but foolishly forgot to copy it or mark the page, can anyone please point me at it? The article was called something like "The Ultimate sensor …."

 

[Black Globe Generator]

Citizen Supplement Four has a whole bunch of sensor rules posted here and here.

There are more advanced sensor rules in DGP's out-of-print Grand Survey for Classic Traveller, but I don't remember much about EW (and I don't have my books handy at the moment). I'm betting that later editions cover this more extensively.

 

[mike wightman]

For why you don't need to worry too much about sensors read this:

http://www.projectrho.com/rocket/rocket3w.html

I personally like the sub-hunt ship combat model, and I think T2300's Star Cruiser to be almost the best incarnation of this.

 

[Andrew Boulton]

FF&S2 is what you need, plus this:

http://au.geocities.com/ca_barnett/traveller/misc/senrules.htm

 

[Black Globe Generator]

Originally posted by Sigg Oddra:
For why you don't need to worry too much about sensors read this:

http://www.projectrho.com/rocket/rocket3w.html

How. Cool. Is. That?

Great site - thanks for sharing the link.

 

[parmasson]

The site is very good and very realistic.
It looks like TL10+ sensors will almost always detect every ship, nearly every time.

Look at all the sources and decide what works best for game balance with your players. After all if it doesn’t help you entertain yourself or others it might not be what you need.

This subject has been done before and if you don’t want to go the realistic route then there are loads of good ideas deep in this forum that can help you explain it if you ever feel the need.

 

[flykiller]

when cassini arrived at saturn it promptly discovered several new moons. these things are hundreds of miles across, some of them are bright white, they weren't trying to hide, and people have been staring at saturn for centuries with every insturment they can come up with knowing they might have a chance to name a new moon - but nobody saw them. I hear all this talk of omniscient sensors, and I have to wonder.

 

[Anthony]

Saturn is an average of 9.5 AU from the earth, with 1.1% of the illumination, and most of the new satellites are quite small. Some of the 'everyone sees everything' sites are optimistic, but at the edges of combat relevant ranges (say, 5 light-seconds) a 10m object (smaller than most Traveller starships) is about as visible at a 100km moon orbiting Saturn.

 

[RandyT0001]

Originally posted by Anthony:
Saturn is an average of 9.5 AU from the earth, with 1.1% of the illumination, and most of the new satellites are quite small. Some of the 'everyone sees everything' sites are optimistic, but at the edges of combat relevant ranges (say, 5 light-seconds) a 10m object (smaller than most Traveller starships) is about as visible at a 100km moon orbiting Saturn.

I thought it was the IR/heat from the ship's power plant that made Traveller ships so easy to detect and not reflected sunlight.

 

[Anthony]

Yes, the power plant is generally visible at greater ranges than reflected sunlight, but sunlight gives us a lower bound on sensible detection ranges.

 

[flykiller]

I thought it was the IR/heat from the ship's power plant that made Traveller ships so easy to detect and not reflected sunlight.

about two years ago some launched satellite went off-course. if I recall correctly it had a thermopile onboard. the command facility had to find it before it could reestablish control, and it took them twenty-four hours, even though they knew almost exactly where to look, it wasn't trying to hide, and it was considerably less than one light second away.

I don't know anything about the subject matter, but I get the impression there's quite a variance between the assertions of "forget it, can't hide, it's hopeless" and real-world performance.

 

[RandyT0001]

Flykiller, I think there is a big difference in the temperature between a fusion reactor that is (assumed to be a 'non cold fusion' type) at one million degrees and a thermopile that uses radioactive decay that is in the thousands of degrees temperature range. Plus I think some IR wavelengths are absorbed by our atmosphere whereas in space there would not be any similar blockage of wavelengths.

One of the problems with the piece that Sigg linked to that might arise is determining mass, size, etc based on the intensity of reactants from thrust in a Classic Traveller universe where the tech assumes a 'reactionless' thrust system.

Anyway, I think a ship can be detected but not positively identified at great ranges but that for combat purposes and resolution the limit is a few light seconds. In order to maximize the possibility of achieving a hit one must use active sensors. Short range is within 150,000 km and long range is 150,001 km to the edge of CT 'detection' ranges (300,000km civilian, 500,000 km military, 750,000km with a positive lock military). IMTU

 

[Anthony]

Originally posted by Randy Tyler:
[QB] Flykiller, I think there is a big difference in the temperature between a fusion reactor that is (assumed to be a 'non cold fusion' type) at one million degrees and a thermopile that uses radioactive decay that is in the thousands of degrees temperature range.

More importantly, there's a difference between a power consumption of a few hundred watts and a power consumption of a few hundred megawatts.

It's also harder to do detection from the ground.

 

[flykiller]

http://www.nasa.gov/vision/universe/watchtheskies/near_earth052104.html

"Approximately 65 percent of the estimated 1,100 large near-Earth objects (those larger than 1 kilometer or .62 miles) have already been discovered, with 45 percent discovered since 1998.

"Yeomans is part of a team of experts assembled by NASA to predict and define goals to detect hazards caused by near-Earth objects... 'Once we reach our goal for 2008, we plan to focus our attention more on finding and tracking smaller objects which are more abundant, but harder to find,' Yeomans said. 'If those smaller objects managed to impact Earth, the damage would be regional, not global.'

...

'We'd like to find objects larger than about 140 meters (459 feet) across, which is the length of one-and-a-quarter football fields.'"

If everything the "it's useless, you can't hide in space" people are saying about IR is true, it seems to me the simple solution for NASA is to orbit an IR sensor system above Earth's atmosphere. Given that anything near Earth's orbit is heated to several hundred degrees when exposed to the sun and then presumably radiates IR, it should take the system only a few hours to locate each and every item that comes anywhere near Earth orbit.

 

[RandyT0001]

Originally posted by flykiller:
If everything the "it's useless, you can't hide in space" people are saying about IR is true, it seems to me the simple solution for NASA is to orbit an IR sensor system above Earth's atmosphere. Given that anything near Earth's orbit is heated to several hundred degrees when exposed to the sun and then presumably radiates IR, it should take the system only a few hours to locate each and every item that comes anywhere near Earth orbit.

There is a big difference between detecting an internal IR source that radiates one million degrees temperature and a couple of hundred degrees of reflected IR that might be reflected off an asteroid but most asteroids don't have perfect nor even exceptionally high albedos so the light they do reflect, either visible or IR, would be distinctly lower than it recieves from the Sun. Plus the fact that radiation intensity drops by the inverse square law as distance increases (at distance x the energy is y, at distane 2x the energy is 1/4y and at distance 3x the energy is 1/9y) and most NEA's are not discovered while close to Earth but at a substantial distance from us. Admittedly detecting that fusion powered spaceship from Earth when it's close to Pluto's orbit is going to be more difficult (if you don't know where to start looking) than if it were just 100 diameters out from Earth but within a short time it could be done.
IMO

 

[Anthony]

If everything the "it's useless, you can't hide in space" people are saying about IR is true, it seems to me the simple solution for NASA is to orbit an IR sensor system above Earth's atmosphere.

Rocks aren't terribly hot; ships are obvious because they consume considerable power. The other thing to remember is that asteroid search is a low budget exercise. The entire telescope capacity dedicated to searching for asteroids could easily be outpowered by the sensors on a type S scout.

 

[avi.hecht]

First thanks for the very prompt responses and pointers to sites…
I found Sigs' site very depressing
My main concern is with long range detection and follows the discussion on the "Dynamics of system defense and other thoughts". The defender has to decide where to put his reserves and how to spread his listening posts, while the aggressor has to decide how to come in – one bunch many small drop ins, jump in far away as close as possible.
One thing the site does show is that my concept of "Submarine" warfare is wrong – in submarine warfare detection ranges are short and accuracy is low (all relative to air combat) In space if we use the heat signature of power reactors and maneuver drives ranges are high…

 

[mike wightman]

I've rationalised things IMTU as the difference between a sensor lock and a weapon firing solution.
I have laser and beam weapon ranges much smaller than is common in Traveller canon - ships have to be closer to hit each other.
The ships know they are out there, and can detect enemies quite a long way away, but they can't fire upon them until they get closer to obtain a weapon lock - obtaining or spoofing the firing solution becomes the sensor conflict.

Missiles can be launced from any range though...

 

[Black Globe Generator]

Originally posted by AviH:
I found Sigs' site very depressing

Remember, there's absolutely nothing that says you have to go with the physics assumed in the article. I found the article informative and helpful but I have no intention of giving up my sensor ranges and their effects on detection and combat - the sensor rules add FUN to space travel!

I enjoyed the fact that it reintroduces the human element - some gamers complain that by the 57th century, "computers will do it all!" The article provides a couple of good reasons why this may not be true, reasons that dovetail nicely with the way elements of Traveller are presented.

Just to make sure you have way too much information to choose from, here's another article on sensors in Traveller...

 

[flykiller]

Rocks aren't terribly hot; ships are obvious because they consume considerable power.

the article in question says, "If the Oscar's crew was shivering at the freezing point, the maximum detection range of the frigid submarine would be 13.4 * sqrt(1510) * 2732 = 38,800,000 kilometers, about one hundred times the distance between the Earth and the Moon, or about 129 light-seconds." if that's true, then it seems to me NASA or whoever just ain't serious at all about these NEO's.