Misjumps and fuel question.

[BP]

Just to throw out there -

Given a 3.25 LY 'volume' of space really puts a damper on 'complimentary fuel dumps' or precipitous rescue patrols.

Without FTL sensors, patrols aren't a good solution when talking 3.25 LY. The best case would probably have to be a 'fixed' (i.e. there longer than three years - or with pre-determinable path) rendezvous beacons to hone in on for fuel or rescue.

Then one has to get to that point - typically at non-relativistic speeds - potentially traveling a good percentage of a year or more. Now there is the power/fuel/life support issue.

There is also the problem of wether the 'fuel' would be enough for a given ship to jump.

Once you throw in the economics of the thing - whether one or thousands of ships/fuel containers to supply/maintain/check- it just doesn't make a lot of sense.

Trying to overcome this by statistical mapping seems counter-productive - since the misjump is an exceptional situation to begin with. Using gravity well of fuel dumps seems quite a stretch given relative size/mass -and they would still need to be detected via signals or sensors and subject to the light speed time lag in the potential 3.25 light year 'hex' before they could be steered to (if not 'fixed' in place as above).

More importantly, if mis-jumps are that much of a problem in the Imperium, well then inaccurate jumps alone would wreck havoc with interstellar trade.

Rikki Tikki's solution addresses these issues quite well => Traveller sector mapping is by main 'planet' - not by star, so his solution doesn't break OTU.

And just having players 'jump' to oblivion on a die roll - why even play?

 

[GypsyComet]

All good points, BP.

The fuel dump as a passive solution is problematic in multiple ways. For starters, assuming the dump and local stars are centered in their hexes (for simplicity, not because I consider it likely) it would still be possible to emerge almost 2 LY from anywhere.

If you put out a whole network of these things in every empty hex, the infrastructure to do so wrecks established parts of the setting (such as the impenetrability of the rifts and the basis for the Battle of Two Suns). You also have to either assume that these are being visited and refilled by someone (a massive job all by itself) or that they are often going to be uselessly empty.

Then there are pirates. Hang a network of readily findable fuel depots in empty hexes and you *know* they'll be used for illicit purposes. Pirates are probably already using some of the deep space rockballs and iceballs mentioned above, but to give them a web of free gas stations as well?

On the flip side, for ATUs, webs of deep sky depots offer additional places for chicanery, lost communities who really have dropped off of the charts (it being easier to lose a depot than to lose a *star*), and societies of deep sky dwellers who rarely if ever visit planets.

 

[captainjack23]

So, thinking about the "low berth fast forward" mentioned by Gypsycomet, actually how much time would be lost ? If you can accelerate up to some portion of c (say .3) one could get players across a parsec in a term or three -and potentially back to their lives (10 years at .3) ?

Question is, how long to accelerate to the cruising speed, and is there enough fuel in a standard load post jump ? Assume you have a 2G drive, and 2 weeks of fuel.

 

[Dave Chase]

So, thinking about the "low berth fast forward" mentioned by Gypsycomet, actually how much time would be lost ? If you can accelerate up to some portion of c (say .3) one could get players across a parsec in a term or three -and potentially back to their lives (10 years at .3) ?

Question is, how long to accelerate to the cruising speed, and is there enough fuel in a standard load post jump ? Assume you have a 2G drive, and 2 weeks of fuel.

Interesting question. Another one is, I missed Gypsycomet's mentioning of low berthing fast forwarding, where is it at in this thread? Or is it in another thread?

...

Dave Chase

 

[GypsyComet]

So, thinking about the "low berth fast forward" mentioned by Gypsycomet, actually how much time would be lost ? If you can accelerate up to some portion of c (say .3) one could get players across a parsec in a term or three -and potentially back to their lives (10 years at .3) ?

Question is, how long to accelerate to the cruising speed, and is there enough fuel in a standard load post jump ? Assume you have a 2G drive, and 2 weeks of fuel.

You need to be able to get the powerplant well down below 1% max output for most of the trip. I expect there is such a function in most power plants, as a bootstrap startup generator, but the next question is whether that 1% is enough for the necessary cold berths. A "cold equation" in more than one way.

A day at 2g gets the ship's velocity rather high, but still only a small fraction of c. Two days helps, but also cuts the fuel available to 10 "days", which means you have to be able to knock the powerplant down to about 1/100th of 1% to have the duration on the cold berths. Yes, you're looking at centuries.

If T4's powerplant and drive model (powerplant fuel is in years, plus thruster plates) is in play, this gets MUCH easier, as you can spend the month accelerating to a comfortable (or uncomfortable, depending on your perspective) fraction of c, rotate your crew through cold berthing for the decade it takes to get to the next hex over, and still hopefully have the fuel left to turn the engines back on for decel.

Back to MGT. If you have the fuel to get the ship up to a decent percentage of c, you may have enough to jump. On a big enough ship with a large-but-insufficient fuel supply, I'd be looking at chopping the ship in two. Drives and most of the remaining fuel on one side and whoever you can't carry on the other with a couple weeks of emergency power. If you can get the drive side down small enough to jump to get help, everyone lives. If you can't, plan a proper greeting for the Flying Dutchman when he shows up to claim you all.

Since Traveller ships aren't built with this sort of lifeboat extremis in mind, we can draw the conclusion that misjumps are simply not as common as the rolls indicate. Wouldn't be the first time.

All in all, its probably best to rig your comms to go to '11', turn them on, and go into cold berths for the 3-4 years it takes the signal to reach someone who can come and get you.

I missed Gypsycomet's mentioning of low berthing fast forwarding, where is it at in this thread? Or is it in another thread?

My first post in this thread.

 

[Dave Chase]

....

I missed Gypsycomet's mentioning of low berthing fast forwarding, where is it at in this thread? Or is it in another thread?

My first post in this thread.

Oh, duh. Low berth versus cold berth.

Too long of a day. No wonder I couldn't find it.

Darn the Capt for using different words :lol:

Thanks for pointing it out. It only took me re-reading 3 times to figure it out. (brain fried I guess from actually working all day in over 5 months)

Dave Chase

 

[ShadowDragon8685]

There is always another option.

If the ship you're on is both Radiation Shielded and Heat Shielded...

You should actually be able to get close enough to a star to get helium from it.

"Tricky" doesn't begin to describe it, but it should, in theory, be possible. The real bitch will be losing heat once you've gained it.

 

[EDG]

So, thinking about the "low berth fast forward" mentioned by Gypsycomet, actually how much time would be lost ? If you can accelerate up to some portion of c (say .3) one could get players across a parsec in a term or three -and potentially back to their lives (10 years at .3) ?

Question is, how long to accelerate to the cruising speed, and is there enough fuel in a standard load post jump ? Assume you have a 2G drive, and 2 weeks of fuel.

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.

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

 

[ShadowDragon8685]

Not to invoke a Startrekism...

Okay, to invoke a Star Trekism, if you have a good computer with a good astrology chart, you can get a fix by identifying the stars' as they appear to you, and then extrapolating from that where you are.

It works, it might take awhile, but frankly, it's mainly crunching numbers by comparing from some really prominant stars, and then honing in, correcting for distance and time, and then setting your course appropriately.

As for are they designed for it... Well, the alternative is "tell your players they die in hibernation, make new ones." So yeah, I'd say they're designed for it - or they work well enough, at any rate.

 

[EDG]

Okay, to invoke a Star Trekism, if you have a good computer with a good astrology chart, you can get a fix by identifying the stars' as they appear to you, and then extrapolating from that where you are.

Yes, because knowing that Venus was in Capricorn on the captain's birthday would certainly save the day! (It's Astronomy, dammit!) :roll:

Besides... you'd know where the stars were however many years ago the light they emitted left them... which isn't where they are now. Maybe ships have ephemerides that include the proper motion of the stars so they can predict where they are now, but would that be able to help you if you're stuck between stars?

And if you just arrived at a random location in the interstellar space between stars, how would you be able to tell exactly how far you were from the (past locations of the) stars around you? I don't think many ships would come equipped with parallax measurers. Maybe you could plot sight lines from each star back to you and find out where they crossed, but there'd still be some degree of error there.

 

[ShadowDragon8685]

Okay, to invoke a Star Trekism, if you have a good computer with a good astrology chart, you can get a fix by identifying the stars' as they appear to you, and then extrapolating from that where you are.

Yes, because knowing that Venus was in Capricorn on the captain's birthday would certainly save the day! (It's Astronomy, dammit!) :roll:

No, but knowing the navigator was born under a doomed sign might help you in choosing to not sail on that vessel.

Besides... you'd know where the stars were however many years ago the light they emitted left them... which isn't where they are now. Maybe ships have ephemerides that include the proper motion of the stars so they can predict where they are now, but would that be able to help you if you're stuck between stars?

And if you just arrived at a random location in the interstellar space between stars, how would you be able to tell exactly how far you were from the (past locations of the) stars around you? I don't think many ships would come equipped with parallax measurers. Maybe you could plot sight lines from each star back to you and find out where they crossed, but there'd still be some degree of error there.

Actually, I'd think that would be rather standard equipment, given that it's just a matter of computing power and math, which is going to be relatively cheap in the far future - especially compared to the possibility of getting lost forever in the void!

And frankly, I'd think your star charts damn well would be a full chart with the motion of the stars programmed in - that would also be only a matter of math and processing power. I'd frankly call all of this just part of the Jumpdrive package and call it good.

And if you got stuck between stars, the principle still applies - just calculate where you are, pick the nearest place you can reach that you can refuel at, derive your travel time, set the alarm clock, and go the hell back to sleep.

(This is also why having Expert medic robots on hand on a ship with cold berths is a good idea.)

 

[AndrewW]

And what happens to the ship payments? After you've been missing awhile maybe some ship tracer with stumble across you. Ok, they would have to know where you where.

 

[ShadowDragon8685]

As a general rule, if you're gone more than 10 years or something, your creditors probably would have written the ship off. In fact, I know that in the US, if a creditor has not or can not act on a debt for six years or more, it's against the law to act on it after that time.

So if you float back into known space with a ship fifty years out of date and younger than your own children/grandchildren, chances are nobody's going to give a crap.



Actually, that would be one way to get out of your debts... Kind of drastic, but taking the ship, loading it with fuel, jumping somewhere out of the way and floating in on grav-drives for the better part of a century. When you get back, there'll be nobody who cares enough to say you didn't get lost in space or suffer a misjump and have to limp home.

 

[Custodian]

Bit of perspective here. I read in a news article the other day that navies can't keep track of every pirate incident going on off the coast of Somalia right now - and that's a vastly smaller volume to cover than 1 cubic parsec of space, which is about 27 cubic lightyears.

However this is looking out for small vessels on turbulent sea at night with a horizon that can prevent direct line of sight.

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.

I would tend to model an empty hex on the space of an absent solar system (plus some significant fringes) rather tha the SiB number. This still makes things hard to detect with non-FTL senses but not impossibly so.

Within this kind of space an articifical object becomes easier to spot than a small boat containing teenagers with heavy weapons.

However I do agree that, nervious referees aside, that misjumps should be rare as this is what the MGT rules say, after all.

So I'm cooling on fuel drops but warming to checking empty hexes for security reasons.

 

[EDG]

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).

If I've calculated right, a 100 metre radius spaceship is about 2e17 times smaller than a cubic parsec. For comparison, an atom is about 1e10 times smaller than a metre. A proton' radius is about 1e-15 metres. So even a large starship in a cubic parsec is probably about equivalent in size to a single electron in a cubic metre of volume.

That should hammer home just how hard it is to find something there.

 

[Rikki Tikki Traveller]

Now, to take the arguement in a slightly different direction.

Your ship misjumps into an empty (truly empty) hex (1 cubic parsec).

Rather than set the ship toward the nearest system and go into cryo for a century or more, why not just send a radio message to that system giving your exact coordinates and then go into cryo with your transponder still on.

In about 3-4 years a rescue ship shows up, charges you a HUGE fee and you only loose 1 term of prior history!

(HUM sounds like an event that I need to add to my career tables).

 

[EDG]

In fact, let's make it even easier - say that each ship is actually a light-day in radius, which very generously represents its maximum scanner range. 1 light-day = 2.6e10 km, 1 cubic light-day = 7.3e31 km³. 1 parsec = 3.09e13 km, 1 cubic parsec = 1.54e40 km³.

So even if you treat a ship as if it's a volume with a radius of 1 cubic light-day (i.e. covering the volume in a sphere with a diameter of 52 billion km across - at least 5 times larger than our solar system), that's still only five-billionths of the volume of a cubic parsec!

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

 

[Pyromancer]

In fact, let's make it even easier - say that each ship is actually a light-day in radius, which very generously represents its maximum scanner range. 1 light-day = 2.6e10 km, 1 cubic light-day = 7.3e31 km³. 1 parsec = 3.09e13 km, 1 cubic parsec = 1.54e40 km³.

My take is that a military grade scanner can pick up a distress signal from light-weeks away.
With that, the chance of finding a misjumped ship in an empty hex improves to about 1 in a few 10.000s.
For one ship. Doing one scan.
With regular patrols, say, a dozen ships every few months, with an optimized search pattern, the chances to be found within a few years improve to 1 in a few hundred. Still small, but not astronomically small.

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.

 

[GypsyComet]

All in all, its probably best to rig your comms to go to '11', turn them on, and go into cold berths for the 3-4 years it takes the signal to reach someone who can come and get you.

Rather than set the ship toward the nearest system and go into cryo for a century or more, why not just send a radio message to that system giving your exact coordinates and then go into cryo with your transponder still on.

In about 3-4 years a rescue ship shows up, charges you a HUGE fee and you only loose 1 term of prior history!

(HUM sounds like an event that I need to add to my career tables).

At least one standard career already has similar.

As for the huge fee, that could be one of those things the Imperium regulates (like fuel and passage prices), especially if deep sky misjumps are common enough that someone is sitting around waiting to hear about them.

Of course, woe betide the ship that jumps into the Abyss Rift, three hexes away from anyone with their ears on.

 

[Rikki Tikki Traveller]

Still 15 years is better than a couple of centuries.