Misjumps and fuel question.

[GypsyComet]

Still 15 years is better than a couple of centuries.

The distance means a lot less signal strength, though. At that distance, the target system needs to have a SETI-like program in place to hear you. Your pinpoint lasercomm signal is flashlighting the whole system at such a low energy density that you'll be lucky to be heard as interference, much less a coherent signal.

The nature of the Third Imperium (and the UWP generation system in general) is that very few systems actually have much of well, anything. Stranded a parsec out of Regina, Glisten, or Lunion is one thing. If the nearest worlds are all like Craw and Dawnworld, you're out of luck...

 

[EDG]

Are we getting the sense of "atom in a haystack" now?

No, we don't. Maybe needle in a haystack. Searching with a strong magnet.

Then you're failing to understand the magnitude of the scales involved.

A "military grade scanner" on one ship won't pick up anything that is "light weeks away". One light-week is 1.81e11 km - 181 billion km, or about 1200 AU (30 times further than Pluto is from the Sun). Anything detected at that distance was there a week ago, and most likely isn't there now or even remotely near where it was when it emitted them. Any signals it's emitted would also be very attentuated at that distance (since they'd be emitted spherically - forget things like LIDAR or whatever, you need to know where your target is for that) and would also have been absorbed and degraded by interstellar dust and gas.

Synthetic Aperture detectors may help, but they'd have to be pretty big to have any chance of detecting anything coherent that far off that's emitted by a lone starship. Neutrino detectors would be the best bet, as they'd be able to detect neutrinos emitted by fusion reactors and those won't get attenuated. But you'd still have the lightspeed problem there, and the ship probably isn't anywhere near it was when it emitted the neutrinos that you're detecting now. But then I suspect that you wouldn't be able to identify whether those neutrinos were emitted by a star or by a fusion reactior so it'd just look indistinguishable from the background stellar neutrinos.

I think my point is still pretty solid. My statistics is flaky so what follows may be wrong, but I think that the probability of two "light-day spheres" overlapping (i.e the misjumped ship and the search ship) if the search ship and the misjumped ship each arrive at a random location in the empty hex so that they can actually detect eachother is actually 1/200millionth x 1/200millionth, which is 1 in 40 quadrillion (4e16), so good luck with that...

 

[Custodian]

Further more this is Traveller where each system snuggly fits into the centre of a hex on a flat plane. 27 cubic light years is the "space is big" number but Traveller is far more PC-centric than a rocket travel sim.

Correction: It's actually 18 cubic lightyears of volume (not 27 - I was using a parsec as the radius for that, when of course I should have been using 0.5 parsecs as the radius).

You're just varying the big number - regardless of the size of this number Traveller space is flat, regular, containable and cosey.

Distances remain the same for the sake of comms but effective volumes of space for the sake of interaction have always been abstract.

 

[EDG]

You're just varying the big number - regardless of the size of this number Traveller space is flat, regular, containable and cosey.

So when people on a planet look up into the night sky in the Traveller universe, they just see a bright line of stars with nothing above and below it? That's what they'd see if space was flat and regular there.

Traveller Space is not "flat". Jumpspace maps may show it as flat, but the realspace it corresponds to most certainly isn't.

 

[captainjack23]

Good luck on pointing the ship in the right direction for it to arrive at a system. Given that all the positions of the stars that are now several lightyears away, and you don't necessarily have a very accurate fix on where you actually are in interstellar space, and the slightest deviation of your course will mean that you miss your target by a very large distance... At the very least, you'd need the ship's computer online to do course corrections as appropriate during the trip.

Yes. One assumes that the typical ship would have better direction than a cheap skyrocket.

Besides. Pulsars can give a pretty good fix AND if one can get some analysis of the local stars (spectra, etc), one can identify them via navigation databases (only a 36 parcec sphere of stars needed from any one jump, after all) ; from there its just a matter of looking up the relative vectors (which one can assume are relative to Reference (the planet) and contained in the "Imperial Practical Navigator database"), and solving for final trajectory.


Then one chooses the nearest likely star, programs the comp to "seek", and nighty night.

And are low berths really designed to keep people safely suspended for many years?

Yes. Plenty of textual refrences to people surviving centuries in a low berth. It's one of the advantages a berth has over just using Fast drug.

 

[captainjack23]

My statistics is flaky so what follows may be wrong, but I think that the probability of two "light-day spheres" overlapping (i.e the misjumped ship and the search ship) if the search ship and the misjumped ship each arrive at a random location in the empty hex so that they can actually detect eachother is actually 1/200millionth x 1/200millionth, which is 1 in 40 quadrillion (4e16), so good luck with that...

Actually, the chance is just 1/200x 10^6. The probability is describing the search ship sphere jumping into contact with the misjumped ships sphere, which is essentially stationary. It's still a big number, though.

Assuming, of course that a 1 week sphere is 1/200x10^6 the volume of a parsec sphere...I took that as written.

 

[EDG]

Besides. Pulsars can give a pretty good fix AND if one can get some analysis of the local stars (spectra, etc), one can identify them via navigation databases (only a 36 parcec sphere of stars needed from any one jump, after all) ; from there its just a matter of looking up the relative vectors (which one can assume are relative to Reference (the planet) and contained in the "Imperial Practical Navigator database"), and solving for final trajectory.

That's all very well, but would all spacecraft carry all the right databases and spectrometers? Would a spacecraft be able to tell a nearby red dwarf from a distant red giant? And a misjump wouldn't necessarily jump you to within a 36 parsec radius either - heck, it might not even jump you to the same era.

 

[captainjack23]

So, how fast can one get going given say, one weeks constant acceleration at 2G ? Relative to lightspeed ?

 

[EDG]

Assuming, of course that a 1 week sphere is 1/200x10^6 the volume of a parsec sphere...I took that as written.

It's the ratio of a one week radius sphere relative to a one parsec diameter sphere. But yes, either way it's a big number.

 

[kristof65]

That's all very well, but would all spacecraft carry all the right databases and spectrometers?

Why wouldn't they? These are starfaring ships - they need the tools to determine their position to chart their course. The databases and spectrometers seem to me to be among those tools they would likely carry.

Sure, they may rely on the future equivelent of our GPS for most navigation tasks, but a good astrogator will want to have all the tools he's been trained to use. Even today's GPS navigated Supertankers still carry old fashioned charts and sextants.

 

[GypsyComet]

Traveller's "g" is 10 m/s/s, so a ship with 2g available thrust is increasing its velocity by 20m/s every second.

There are 60 x 60 x 24 x 7 = 604,800 seconds in a week.

Final velocity after a week is thus roughly 12 million meters/second, or about 4 percent of lightspeed. From hex-center to hex-center, around 80 years.

Assuming you don't hit something. At 0.04c, that's going to leave a lot more than a scar...

 

[Custodian]

You're just varying the big number - regardless of the size of this number Traveller space is flat, regular, containable and cosey.

So when people on a planet look up into the night sky in the Traveller universe, they just see a bright line of stars with nothing above and below it? That's what they'd see if space was flat and regular there.

Traveller Space is not "flat". Jumpspace maps may show it as flat, but the realspace it corresponds to most certainly isn't.

A character in the Traveller universe won't see a flat universe but in game terms the Traveller universe is still flat. Fortunately I have both the CT and MGT to refer to at the moment so I've been able to check this.

Traveller works on these kinds of abstractions to make things playable.

Neither system uses the term 'jumpspace maps' either.

However you are always welcome to use it in your OTU, of course.

 

[captainjack23]

That's all very well, but would all spacecraft carry all the right databases and spectrometers?

Its stuff that we can do now, so by the tech rules the equipment will be tiny and cheap. The database is just a bit bucket - I suspect one can get basic emergency navigationdata for all of known space on a gigabyte thumb drive. Its likely that in a beurocratized empire, and especially with a bank owned ship, that such nav resources are required by law -as well as good sense.

besides, if you don't have the mandated safety equiptment, who's fault is it if you drift forever in the icy dark of space. ?

Would a spacecraft be able to tell a nearby red dwarf from a distant red giant?

See above. We can now, and it wouldn't take a massive amount of computing power to derive location from very crude data; it's essentially a comparative cluster analysis, looking for specific groupings of very basic data. Heck, I'm running somthing more complicated on my desktop right now....wait, it's done !

Given 200 stars , using bonehead spectra observations (is it red ?y/n, is it blue ?y/n) I guarantee that you can find yourself. Heck, probably 20 would do for a first iteration.

And a misjump wouldn't necessarily jump you to within a 36 parsec radius either - heck, it might not even jump you to the same era.

Well, the future is an issue, yes. You could however get the date by pulsar observation. So you could know how VERY VERY SERIOUSLY you pissed off the ref.

As to the distance, its the basic misjump distance in CT (1-6 d6), and IIRC its pretty vaguely defined in MGT, so I just went with that.

In any case, If you land anywhere in charted space, you can find out where you are as above. If you don't land in charted space, you're clearly in "world of Hurting" space, and, thus, out of luck.....so, next time, bring good beer to the game

 

[kristof65]

RE: Navigational databases -

Something that occured to me whne thinking about what ships would/wouldn't carry. The star catalogs they have would be much, much more precise than what we have now. Think about it - everything we currently know about the galaxy and universe - positions of stars, galaxies, etc, is pretty much triangulated from with in our own little solar system - and most of that from points that are no more than 186 million miles apart, which is VERY insignifcant on a stellar scale.

A star faring society, however, would have much more accurate star charts, particularly one that's been around as long as the 3I. The data for most stars will have been gathered from within that star system, or no more than a few parsecs away. Exact spectrums, number of planets, orbital data, etc will be pretty darn accurate.

More importantly, how does that relate to this topic and help the stranded space ship?

Think about this in terms that most people are familar with, or can recreate. Go to Google Earth or any website/app that lets you look at satellite photos. Zoom into any random house with a car parked in the driveway, and try and identify what make/model the car is. You can't. Now zoom into your own house, or that of a friend or neighbor - can you identify the car(s) parked there now? I bet you can. Why? Because the internal "database" you have already knows what the car is supposed to be - you just need enough visual clues to match it to the database.

Same goes for this stellar database most ships would carry - the data is already there, the astrogator just needs enough information to identify a few star systems to the point they can triangulate a position. It doesn't matter if he can't get an exact spectroscopic scan - he only needs one accurate enough from enough objects to match a pattern in the database.

 

[EDG]

A character in the Traveller universe won't see a flat universe but in game terms the Traveller universe is still flat.

Then it's not flat. Abstractify it anyway you want, but you're still dealing with a volume of space whether you like it or not. You may abstractify a planet so that it's just a starport and a community around it, but that doesn't change the fact that it's actually a large spherical body orbiting a star that has billions of square kilometres of other stuff on it.

 

[Custodian]

A character in the Traveller universe won't see a flat universe but in game terms the Traveller universe is still flat.

Then it's not flat. Abstractify it anyway you want, but you're still dealing with a volume of space whether you like it or not.

I thought you might understand the difference between the perspective of a character in a role-playing game and the way Traveller works as a game but I'm not so sure now.

Note: I'm explaining how Traveller is published in CT and MGT - your OTU can vary. You don't need to justify your personal decisions to me. Whatever you do in your personal games obviously works for you.

An in-character scientist will be able to prove that the world is flat but this does not stop Traveller space being flat to keep the game manageable, imaginable and dramatic.

What makes you think I don't like volumes of space? I hope it's not due to poor memory or reading skills because I wrote very early on:

I would tend to model an empty hex on the space of an absent solar system (plus some significant fringes) rather tha[n] the SiB number.

Note that this is a significant volume of space.

I doubt you'll be able to a find published, official CT or MGT scenario that ventures beyond that kind of volume within any given Traveller hex, empty or not.

Why? Because it's to keep the game manageable, imaginable and dramatic.

 

[EDG]

I thought you might understand the difference between the perspective of a character in a role-playing game and the way Traveller works as a game but I'm not so sure now.

I don't view Traveller as a game - I view it as a setting, set in a universe that should be much like our own (which is why I balk at unrealistic worlds and stars and distributions etc). The flat space argument has gone on for years and as far as I can see the general consensus (to make any kind of sense of it) is that jumpspace maps show space as flat because that's just how jumpspace corresponds to realspace. But realspace itself is the same as our own. The distance between Sol and Alpha Centauri in Traveller terms may be J1, or one hex on a map, but in realspace even in Traveller it's still 4.3 lightyears.

The game has to fit around the setting for me, not the other way around.

Why? Because it's to keep the game manageable, imaginable and dramatic.

I can manage and imagine things on large scales and keep them dramatic as well. I don't need that dumbed down for me. YMMV, evidently.

 

[Custodian]

don't view Traveller as a game [...]

The game has to fit around the setting for me, not the other way around.

In your OTU, along with whatever people you want to reach consensus with, you're more than welcome to do this.

However I consider Traveller to be a game and on this board I consider the discussion of the MGT game, with all it's implications and the way it flavours the setting, to be more pertinent and on-topic.

 

[EDG]

In your OTU, along with whatever people you want to reach consensus with, you're more than welcome to do this.

Okay... so long as you realise that you're presenting your view as if it's what the OTU says, which it doesn't. In one's own TU (there's only one OTU - the OTU of whatever ruleset you use - and that may or may not have relevance to the setting one actually plays in), one can do whatever one likes, but by making blanket statements like "Traveller space is flat, regular, containable and cosey" you're just trying to impose your own view over everyone else's. The OTU certainly doesn't say that realspace is flat, regular, containable or cozy - that's just your interpretation of it.

And at least I have reality to back me up. I have no reason to believe that the nature of space is different in Traveller compared to what it is in reality, so that's what I go with. Systems aren't arranged nicely to be in the exact centre of one-parsec wide hexes in reality, so why should they be in Traveller? And at least reality is something we all have as a common reference, so it's more useful to compare to that rather than to arbitrary, subjective abstractions of "regularity" and "containability".

Maybe you just see Traveller in a strongly Gamist way, and I see it in a strongly Simulationist way, I dunno. I guess we'll have to just agree to disagree.

However I consider Traveller to be a game and on this board I consider the discussion of the MGT game, with all it's implications and the way it flavours the setting, to be more pertinent and on-topic.

I don't think MGT really discusses any of this... the OP was asking about misjumps and how to refuel in empty hexes. I'm just illustrating the probabilities of being able to find another ship that's misjumped into an empty hex - heck, a ship could misjump into an occupied hex and still be light-weeks away from the target system and about as undiscoverable.

 

[Pyromancer]

A "military grade scanner" on one ship won't pick up anything that is "light weeks away". One light-week is 1.81e11 km - 181 billion km, or about 1200 AU (30 times further than Pluto is from the Sun). Anything detected at that distance was there a week ago, and most likely isn't there now or even remotely near where it was when it emitted them.

Where is the problem with that? The moment I know where it was, the moment I know where I have to take a closer look.

Any signals it's emitted would also be very attentuated at that distance (since they'd be emitted spherically - forget things like LIDAR or whatever, you need to know where your target is for that) and would also have been absorbed and degraded by interstellar dust and gas.

147dB of free-space path loss, and I think we can omitt interstellar dust and gas. Those few atoms won't hurt much.

Synthetic Aperture detectors may help, but they'd have to be pretty big to have any chance of detecting anything coherent that far off that's emitted by a lone starship.

Wasn't the point of synthetic apertures that the antennas itself could be quite small, they only had to be far apart? And does that really help detecting weak signals?

I think my point is still pretty solid. My statistics is flaky so what follows may be wrong, but I think that the probability of two "light-day spheres" overlapping (i.e the misjumped ship and the search ship) if the search ship and the misjumped ship each arrive at a random location in the empty hex so that they can actually detect eachother is actually 1/200millionth x 1/200millionth, which is 1 in 40 quadrillion (4e16), so good luck with that...

Your statistic is flaky, but your point is still solid. The chances are small.
With my assumptions, they are a little bit better, but still too small to bet your life on. It really doesn't matter if your chances of survival are 1:10.000 or 1:1.000.000.000. In the end, you are dead.