Detecting Jump...

[HighKeeba]

Has anything ever been written or discussed about if it's possible to detect a vessel as it jumps into a system? In MTU I've ruled that if a ship appears just outside the 100D limit it is detectable by both orbital and ground stations as long as they're sensors are pointing in its general direction. Thus, if said ship was determined to be hostile (…after failing to answer repeated hails or not displaying the appropriate IFF signal) it could be targeted and intercepted fairly easily. I've explained this to players as being the result of a blast of photons, tachyons, or some other sort of sub-atomic particle (…or simply appearing less than 30K clicks near, or between, ships is good enough for visual identification). If a ship breaks out of Jump a distance outside the 100D limit, and if no other units are nearby to "see" it appear, then it can coast under EMCON toward its target in order to observe, attack, or to do some other form of mischief.

I'm in the middle of writing an adventure where one aspect is for the players to figure out how to get to the system, and then make planetfall without arousing a lot of attention. I thought about placing several moons around the primary world and then cooking up a story about a "smuggler's route" that would allow them to accomplish this task (…plus the added benefit of making them work for the information in the first place). But (…and this is part of my question, I suppose) can't some sub-atomic particles easily pass through sold matter, like the aforementioned moon, so that they could be detected?

Any reference or rule I'm missing here? I have all of the books for GURPS Traveller and most for Classic and Mongoose.

Thanks for the help!!

 

[Swiftbrook]

Two references that I know of:

To those looking at a starship returning to normal space, a blue haze begins to form. For an instant, a point of brilliant blue-white light forms at its center, which suddenly stretches out to become a line and then bursts into the brilliant three-dimensional grid pattern made by the lanthanum hull web. The haze fades out slowly behind the ship, while the grid quickly loses its charge and returns to normal.

The most notable of these is a product of its Kurgin Hyperflex IV jump drive. When transitioning from jump space to real space, the drive discharges an inordinate amount of energy. This energy burst shows up well on most ship's sensors, thus announcing the ship's arrival in a given system.

Seems like I've seen a task somewhere, just not sure where.

-Swiftbrook

 

[Commander Truestar]

As I've suggested in other threads,

1) Most worlds advanced enough(or with other forces in system that are advanced enough: Ex: Jae Tellona/Spinward Marches IN Base) have traffic control. Having traffic control would allow them th advertise to neighbor systems the "quadrants of their space above and below the world(Zenith and Nadir) as restricted for arrival or departure. So a ship arriving in-system from the wrong vector would be seen as an intruder.

2) All ships must have active transponders. Starports would have, again where technologically legitimate or logically imported, constellations of robotic probes in their traffic control regions...including near the 100d limit(like our modern constellations of cell phone sats). So any ship entering the pattern without a transponder would stick out like a thumb. And any ship with a transponder that does not correspond to any already-tracked transponder from further out would likewise glow like a star.

Moving beyond that, there are numerous partials which we track scientifically today by capturing them in the lowest mine shafts we have because we need them to slow down as they do passing through dense matter like a planet.

My best recommendation is to either do the drift strategy of emerging well beyond the 100d limit and drifting under Econ(as you mentioned) or to make the players seek out a freeport where they can purchase some "transponder control systems".

Marc

 

[Major B]

HIWG's Imperial Navy Handbook (version dated 28 May 1992) had a mention on this subject. It is not canon but you may wish to adopt this bit for YTU:

Entering jumpspace is an irrevocable decision point. The ship enters a higher-energy domain, and travels in it until "jumpspace friction" lowers its energy below the level needed to stay in that domain. (The source of jumpspace friction is unknown. Jumpspace friction is as abstract as the normal idea of friction.) The ship then re-enters normal space, shedding additional energy between jump-insertion and normal space levels.

That led to settling a sensor issue. Considering normal space energy levels and those needed to enter jumpspace, it seemed enough energy became visible light to make detection of an arrival easy.

 

[Andrew Boulton]

IMTU (and hinted in canon), jump entry flash is impossible to hide. Exit flash is much smaller - you really have to be looking in the right place (assuming transponder is off). Higher-tech, better traffic control, and Navy/Scout bases would make detection more likely.

 

[Sturn]

Mongoose Traveller has jump detection rules. Don't yell at me if you hate Mongoose, just providing more information.

In a nutshell-

Incoming jumps are detected automatically if within sensor range.

Jump drives with stealth technology are available. These require the sensor operator to detect the jump with a task roll (not automatic detection). The difficulty varies by range.

 

[CosmicGamer]

Unless the transponder is somehow off, I would think the signal from a new arrival would easily be detected.

 

[the angle]

I have a great deal of difficulty with the whole transponder issue. The notion of a tamper-proof transponder doesn't sit well with high tech or frontier travel. There's no way a transponder can't be modified or removed.

Ultimately, though, your best bet for entering a system undetected is to do it well outside traffic control's normal sensor range and then drift in at very low energy output. Even that would be nearly impossible at a planet with the tech development of, say, present-day Earth. Nothing enters Earth orbit without us knowing about it.

Steve

 

[HighKeeba]

Reference?

Mongoose Traveller has jump detection rules.

You wouldn't happen to know where that reference is by chance? I've been pouring over my Mongoose collection and can't seem to find it.

And, for the record, I have nothing against Mongoose Traveller at all, so no raised voices from this sector. Indeed, the great majority of games that I've run in the past all used GURPS.

Thanks!

 

[HighKeeba]

Transponders

I have a great deal of difficulty with the whole transponder issue. The notion of a tamper-proof transponder doesn't sit well with high tech or frontier travel. There's no way a transponder can't be modified or removed.

In MTU I've allowed players to either replace or hack transponders, but I usually make it prohibitively expensive if they hire someone outside the party to do it or very difficult in terms of skill rolls and luck if they choose to make the attempt themselves.

Simply being able to turn it on or off is another matter entirely IMO. While not strictly legal (...especially in the core systems), I can see the justification for a Free Trader wanting to have the ability to avoid being too easy to track while operating in 'hostile space'....thus, in my view it isn't as difficult in terms of game mechanics to pull this off. If this modification was discovered during an inspection it would probably, depending on the system, result in a citation or small fine/bribe rather than having the ship impounded and the crew imprisoned for a transponder that was obviously tampered with.

 

[far-trader]

Has anything ever been written or discussed about if it's possible to detect a vessel as it jumps into a system?

First question is do you mean for the game or reality? The answers are very different. The game generally (imo) presumes stealth is possible, reality on the other hand says pretty unequivocally "there is not stealth in space." The best source I've found for this discussion is on the Project Rho pages (aka Atomic Rocket) here:

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

(and there's lots of other great topics there as well)

Give that a read and then...

...repeat "it's just a game" and ignore reality if you want a chance at stealth because it's fun

CT has long allowed that the transponders can be turned off. And it is accepted practice to do so before entering an unknown or known hazardous system. To avoid being a beacon to every pirate in the system. However once your passives have determined there is no immediate threat, or that you are indeed in a "safe" system you are expected to turn your transponder back on. Or you will be treated as the hostile by everyone else. You'll be lucky if all that happens is you lose you ship and go to prison if you're caught trying to lurk.

CT also has some pretty limited (unrealistic) ranges of detection. Just 150,000km for civilian ships to 600,000km for military ships. With a tracking range of 900,000km for both. Those are something like 100 times less than real (current tech) detection ranges for small ships (up to about 1000dtons) running cold (no power and at zero degrees celsius), not the presumed active thrust and power mode.

CT also presumes, from everything I recall running across, that there is no jump flash. At least on entering a system/exiting from jump space.

Or you might take those ranges as how close you'll get before the detecting ship has done a complete sky scan. Current tech can process a full sky sweep in about 4 hours according to Project Rho so that's possible. For certain detection, for one ship. The more ships the more likely you'll be detected sooner/further away. Time for the mantra again "It's just a game." For me, I want and accept some stealth, but require some detection reality.

I simplify it for CT, usually along the lines of:

Detection 1 - Class A or B Starport, or Navy or Scout Base in system - Detection is automatic and immediate for all ships in all states. No sneaking in at all. "There is no stealth in (properly monitored) space."

Detection 2 - Class C Starport in system - Detection of active ships out to 6 million km is automatic and immediate, passive ships are undetected for 4turns (about 1 hour) or until closer (within 600,000km). Detection of passive ships out to 600,000km is automatic and immediate.

Detection 2 - Military Ship - A single military ship is equal to the above Class C Starport capability but requires a roll to achieve. Roll 13+ per turn with a DM+1 per computer model number. Multiple ships may improve the odds with each rolling to detect if separated by 300,000km.

Detection 3 - Class D Starport in system - Detection of active ships out to 1.5 million km is automatic and immediate, passive ships are undetected for 8turns (about 2 hours) or until closer (withing 150,000km). Detection of passive ships out to 150,000km is automatic and immediate.

Detection 3 - Civilian Ship - A single civilian ship is equal to the above Class D Starport capability but requires a roll to achieve. Roll 13+ per turn with a DM+1 per computer model number. Multiple ships may improve the odds with each rolling to detect if separated by 75,000km.

Detection 4 - Class E or X Starport in system - No detection facilities in place that can't be beat by standard ship operation.

Adjust up or down based on:

Military Stealth - Treat detection as one level harder.

Large Ships - Ships over 1000dtons are one level easier. Ships over 10,000dtons are two levels easier. Ships over 50,000dtons are three levels easier. But note that Class E and X have no sensors at all, it doesn't matter how easy it is.

Small Craft - Ships under 100dtons are one level harder.

Tracking ships once detected is automatic and unlimited by range until lost by either jumping or occluding. If a ship jumps out they are gone of course. If the sensor is blocked by occlusion (running behind a planet, gas giant, or star) then detection has to happen again once the ship is no longer occluded.

These are detection ranges only. Targeting ranges are limited to 600,000km by military ships and 150,000km by civilian ships. Targeting sensors are active sensors and ships using active sensors are not passive for detection purposes.

Eg 1: A 400ton Trader entering a system with a Class C starport is civilian (no military stealth) and under 1000dtons so it is the standard detection. It can come in cold from jump and not be detected for an hour or until it gets within 600,000km, whichever comes first. Its 20ton Launch would be one level harder to detect for its size, so it could drift undetected for 2 hours or until it hit orbit, whichever comes first.

Eg 2: A 400ton Patrol Cruiser entering a system with a Class A starport is under 1000tons but has military stealth so it is one level harder to detect. It can come in cold from jump and not be detected for an hour or until it gets within 600,000km, whichever comes first. Its 30ton Boat also has stealth and would be one level harder to detect for its size, so it could drift undetected for 2 hours or until it gets within 150,000km, whichever comes first.

Special Note: Drop Capsules are even harder to detect. They have military stealth of course and are much smaller than small craft. I treat them as three levels harder total (treating Detection 1 as Detection 4). They can be inserted into even the most secure systems and make it to the ground undetected. My reasoning is purely game play. It makes small strike ships with drop capsules a key ingredient in combat. They get in undetected (briefly at least) and launch drop capsules to drift in and make planetfall to take out the system defenses such as deep meson sites, missile bases, and such before the regular fleet can safely approach to blockade or invade in force.

And of course the above is simply my take on it, and just guidelines even then. If the plot requires the players to make a sneaky approach well maybe they notice the system is due for a spike in solar flare activity and with a little luck a flare will blind the sensors in the system just long enough. Of course they'll be just as blind... Or maybe the sensor net is down for repairs after some virus knocked it out, a secret known to only a few but the players have heard the rumour. Or is it a trap...

This all refers to official Imperial detection systems of course. Local detection systems based on resources and TL may also be a consideration. They will rarely be better or worse than Imperial systems in place though. But it is pretty hard to hide a 500,000ton Dreadnaught orbiting a world even if the population below is relying solely on Mark 1 Eyeballs. And some of them will have seen the streaks of fire as the Drop Troops came in hot the days before.

So fold, spindle, and mutilate for your own needs

 

[far-trader]

I knew I was forgetting some comments in my earlier reply but I was rushed (and they may have been answered already)...

...I thought about placing several moons around the primary world and then cooking up a story about a "smuggler's route" that would allow them to accomplish this task (…plus the added benefit of making them work for the information in the first place).

Seems to me if there were a smuggler's route that the players could find out about that the authorities would also know it, if they cared. And if it were some feature of astrogation it would long ago (thousands of years old Imperium) have been figured out and sensors in place, again if it is important enough.

But (…and this is part of my question, I suppose) can't some sub-atomic particles easily pass through sold matter, like the aforementioned moon, so that they could be detected?

Yep, neutrino emissions for one iirc, which are a by-product of fusion reactors. But again Traveller seems to suppose some shielding of radiation that may make this difficult to detect.

In the end it'll come down to a handwave, not realism, on your part if you want stealth

 

[aramis]

Not to mention the gravity wave disturbances. To date, we have little proof of gravity propagation speeds... because we have no sudden appearance nor disappearance of significant mass....

But whatever speed it propagates at, we know that densitometers can be used to map masses to several dozen meters... so they should be able to detect the fluctuations of something suddenly appearing or disappearing.

And, as Dan points out, yes, any blind areas in the near system will be monitored if there is sufficient population and tech to do so.

 

[Sturn]

You wouldn't happen to know where that reference is by chance? I've been pouring over my Mongoose collection and can't seem to find it.

High Guard Bk2. Page 43, top right corner under Stealth Jump option. I don't think there is anything about detecting jumps in the core book.

 

[Diveguy]

I knew I was forgetting some comments in my earlier reply but I was rushed (and they may have been answered already)...



Seems to me if there were a smuggler's route that the players could find out about that the authorities would also know it, if they cared. And if it were some feature of astrogation it would long ago (thousands of years old Imperium) have been figured out and sensors in place, again if it is important enough.

Unless you consider the authorities may WANT that route(s) open, for various reasons - with plenty of real world analogs. Everything from the fact that "We know the bad guys come in here, we can pick and choose who we want to bust." to "Give us our cut, or you all get busted." to the local/Imperium reps using it to move their own people/products.

For the even more cynical it gives the system a nice scapegoat - that "threat" which requires funding, military personnel etc to protect against.

Just a few thoughts on it...

 

[Icosahedron]

Interesting detection rules, FT, I might 'borrow' those.

Reminds me of the Covert Insertion rules I devised for Pocket Empires. Basically the maximum size unit you could insert past enemy defences was the reciprocal of the defence size. Eg, a system has a Size 10 space defence fleet and a Size 4 ground defence force, so the largest unit you could secretly insert into the system would be Size 0.1 (1/10) and the largest unit you could secretly land would be Size 0.025 (1/10*4). The maximum insertion force would be an Impossible task, and would get easier as the size reduced.
Never got to playtest them, though, so caveat emptor.

All strictly non-canon, of course.

 

[HighKeeba]

First of all, thanks to all such detailed answers, they were exactly what I was looking for and has added quite a bit of fresh fire to the discussions on this subject for me and my players.

First question is do you mean for the game or reality? The answers are very different.

The framework that I've always worked from for MTU (...and seems to work well for my players in terms of holding their interests and keeping it fun) is that technology in the far future will allow a ship with the right equipment to 'run silent, run deep.' Indeed, even though we understand intellectually that the two environments are quite different for the most part, we often equate movement between spacecraft as being somewhat similar with submarine operations in the real world.

I try to balance this by saying that, since hiding a spacecraft's emissions 'in reality' is difficult at best, regardless of the Tech Level, advanced stealth systems are quite pricey (...well out of reach for the "common sophont") and work best on smaller ships. No discussions on an upper tonnage limit for these systems has come up yet, but I'm thinking beyond say 1500 to 2000dtons there would be too many "cracks" or "overlaps" in the hull to make it practical to apply these systems. Then again, there might be some political, or ethical reason why certain ships aren't designed to "hide with extreme prejudice"... cruisers, battleships, and dreadnoughts are suppose to be seen because one of their primary missions is to project power...and arriving in system buttoned-up under full EMCON might send the wrong message. Also officers and personnel aboard these ships might be institutionally prejudiced to think it "improper" or at least "not strictly honorable" to sneak up on an opponent, even though they understand the tactical and strategic necessities of such an ability.

Seems to me if there were a smuggler's route that the players could find out about that the authorities would also know it, if they cared.

Good point. I figured that a repressive government with tight controls on the local economy would understand the necessity of allowing some sort of black market to operate under their noses as long as it doesn't upset day-to-day functioning (...Iran and N.Korea come to mind here as modern examples). Part of the plot hook I've been working on is the disappearance of two ships along such a route, and the players are hired to discover their fates. I suppose with the proper amount of legwork, role-playing, and dice rolls they could discover the names of certain government officials that have been allowing ships to land "undetected" as long as they get a cut of the profits. Of course, if those officials happen to have been transfered, forced into early retirement, or...insert your favorite euphemism for murder most foul, then things might get even more interesting.

 

[Hal]

Has anything ever been written or discussed about if it's possible to detect a vessel as it jumps into a system?

<Snipped stuff>

Any reference or rule I'm missing here? I have all of the books for GURPS Traveller and most for Classic and Mongoose.

Thanks for the help!!

There are two sources I've come across regarding "jump flash" if you will. The first is from the STARSHIP OPERATORS MANUAL - which is NOT considered to be canon, but it describes the simple fact that starships energizing their grids can be detected visually as - well, energizing their jump grids <g>. High Guard also indicates that ships preparing for jump can be detected - with jumping ships required to take two turns (ie 40 minutes) to enter into jump, or 20 minutes if the power level of the powerplant is twice that of the jump level of the jump plant.

However - GURPS TRAVELLER does in fact, have rules on jump emergence and jump entry. It is predicated on the concept that entering and exiting jump space is an electromagnetic event (ie visible flash) that can be detected out to a given range based upon the sensors of the ship, etc. It also has rules for how far away a transponder can be detected based upon the signal strength of the transponder itself. While I don't have my GURPS TRAVELLER books handy as I write this, let me know via email hal att roadrunner daht com if you want the specifics from the GURPS TRAVELLER rules set.