Long Voyages of Exploration

[marginaleye]

Here's a scenario:

Suppose you want to conduct a really long-range exploration/colonization mission, across a couple of thousands of parsecs of uncharted wilderness (which means no refined fuel, and no regular overhauls). Suppose, furthermore, you're in a big hurry, so the slow-but-safe approach (some combination of low berths, hydrogen ram-scoops, and sublight propulsion) isn't a viable option -- the colony ships have just got to be jump-capable. Is this even possible?

According to the rules, as written, it probably isn't. If a starship's jump drive doesn't get overhauled every year, the risk of misjump begins to go up. A voyage through a couple of thousand parsecs of wilderness would involve several decades without an overhaul, making a misjump (or worse) unavoidable.

Can anyone suggest how to make a voyage like this possible, without screwing up the rules for "mundane" starship operations and maintenance. I'm envisioning some combination of (a) "ruggedized" jump drives (which cost more, and take up a lot more space), (b) lots of space dedicated to spare parts, onboard testing and repair facilities, and so forth, (c) at least one extra jump drive (so the voyage can continue while the one is being inspected, scrubbed out and recalibrated), and (d) extra engineers (more than the canonical 1 per 100 dtons of drives installed).

Does this sound like a fair "hand-wave" around the problem of travelling very long distances without visiting starports? Yes, in theory, anyone (including player characters) could do this sort of thing, but who really wants to lose a large fraction of one's starship's internal volume for a benefit of dubious value? Ships equipped as I describe above would be at a severe disadvantage both for hauling cargo and fighting!

 

[Shadowdancer]

We started a campaign like this once in CT years ago, but never got past the planning and outfitting stage. We were going to use multiple ships. One was completely dedicated to carrying spare parts and workshops. Another ship had all the necessary equipment to mine, refine and process ore into metals, so that more spare parts could be manufactured along the way, if required.

We envisioned the campaign to be a full-blown Wagon Train or Caravan Through Space. I guess we watched too much "Battlestar Galactica."

 

[vutpakdi]

Originally posted by marginaleye:
Here's a scenario:
Does this sound like a fair "hand-wave" around the problem of travelling very long distances without visiting starports? Yes, in theory, anyone (including player characters) could do this sort of thing, but who really wants to lose a large fraction of one's starship's internal volume for a benefit of dubious value? Ships equipped as I describe above would be at a severe disadvantage both for hauling cargo and fighting!

Why isn't it possible around the current rules with slight bending? Seems that if you have a tender ship (or two) designed to maintain ships/drives and machine needed parts, you could have a fleet that could do long range exploration.

Yes, ships equipped as you described would be at a disadvantage for cargo and fighting, but their internal volume would hardly be taken up by things of dubious value. Rather, with respect to the mission, their internal volume would be taken up by things of incalculable value since without them, the mission fails.

Seems like you'd want to have a fleet of a number of different ships:
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• a number of colony ships</font>
• a number of defensive ships</font>
• pathfinder ships to scout ahead</font>
• supply ships</font>
• repair and maintenance tenders</font>
• hydroponic/foodstuff growing ships</font>

So, essentially what Paraquat said: a version of the Battlestar Galactica fleet. Or, alternately, the Homeworld game fleet.

Ron

 

[Hecateus]

There is an article somewhere descibing a Zhodani Core expedition. It goes over many of these issues. I am not sure where it is though.

 

[TheDS]

If he ship is big enough, you don't really need a whole fleet. There's no good reason why a few machine shops, some carried miners, and a dismountable jump drive (with corespondingly large repair bay to put it in) could not be put aboard a ship. SOmething of only 10,000 tons should be sufficient to the task, and having a spare drive aboard is a great idea.

The ship won't have as much in the way of weaponry as your standard cruiser would, but you don't want to send these things into combat anyway.

 

[Hecateus]

The problem arises around the Great Interstellar Rifts. Fuel must be imported and protected at depots...this was described in the Zhodani coreward thingy:
> Linky <

 

[Drakon]

Pardon, I am kind of new here.

It seems what you want is a jump capable depot level repair ship, or "tender" for several of your smaller vessels. The trick is to carry the repair facilities with you, possibly aboard this special ship, to service the other craft in the fleet.

Also the issue of redundancy should be investigated. Having a ship with dual jump engines means only having to service them once every two years instead of one.

At least that was the Navy's solution,redundancy and tenders, for submarines.

 

[marginaleye]

It seems what you want is a jump capable depot level repair ship, or "tender" for several of your smaller vessels. The trick is to carry the repair facilities with you, possibly aboard this special ship, to service the other craft in the fleet.

Also the issue of redundancy should be investigated. Having a ship with dual jump engines means only having to service them once every two years instead of one.

At least that was the Navy's solution,redundancy and tenders, for submarines.

The problem with "tender-based" solutions can be boiled down to this simple question: "Who overhauls the tender's jump drives?" If you can design a tender capable of operating in the wilderness for several decades, than you can also design a colonization ship capable of the same feat.

Right now, I'm leaning towards a streamlined cruiser-sized colony ship (about 50,000 dtons, possible at Tech Level 11 with a Model/5 computer, according to "High Guard"), carrying a few (5 to 10) small (100 to 400 dton) jump-capable scout ships. I'm envisioning a very early Solomani expedition out to rimward, launched before the rather surprising outcome of the Interstellar Wars could be forseen (when the fall of Terra to the First Imperium still seemed like a real and threatening possibility). It might be even more amusing if the expedition was launched even earlier, before the Terrans had established a world-state, but I'm not sure whether a Tech Level 10 colony ship could cover the distance and carry a large enough payload to establish a viable colony (at Tech Level 10, the best computer available is the Model/4, limiting the hull size to 10,000 dtons, and jump-2 is impossible, leading to a longer, slower, and thus more punishing trip).

Actually, launching the expedition a little later -- perhaps during a particularly bleak part of the Long Night -- might make more sense. I suspect that the very early Solomani didn't know enough about jump drives to foresee the problems spending decades without overhauls would cause...

 

[TKalbfus]

Ever consider an Interstellar Ramjet equipped with a jump drive and fuel processors? It would have to reach 6% of the speed of light. Relativity doesn't yet kick in at this speed, but its magnetic fuel scoops should be able to collect interstellar hydrogen at this velocity. No stopping at gas giants would be required and rifts wouldn't be a problem either. It would have to get to 6% of the speed of light first, this would require multiple stages. The ram jet would need spare jump drives and self repair capacity, but it would not have to slow down until it approached its destination. It would just make one jump after another with some time in-between to collect interstellar hydrogen. Even a voyage to the Andromeda galaxy is possible. Low berths of Generation ship arrangements might be necessary of course. The ship enters jump space at 6% of the speed of light and emerges from it at the same velocity.

 

[marginaleye]

Ever consider an Interstellar Ramjet equipped with a jump drive and fuel processors? It would have to reach 6% of the speed of light. Relativity doesn't yet kick in at this speed, but its magnetic fuel scoops should be able to collect interstellar hydrogen at this velocity. No stopping at gas giants would be required and rifts wouldn't be a problem either. It would have to get to 6% of the speed of light first, this would require multiple stages. The ram jet would need spare jump drives and self repair capacity, but it would not have to slow down until it approached its destination. It would just make one jump after another with some time in-between to collect interstellar hydrogen. Even a voyage to the Andromeda galaxy is possible. Low berths of Generation ship arrangements might be necessary of course. The ship enters jump space at 6% of the speed of light and emerges from it at the same velocity.

As a matter of fact, I did think of this (and, if my memory serves me correctly, I think I may have even floated the idea on the T.M.L., in connection with a voyage to one of the Magellanic Clouds, some years ago), but there's one very serious problem with the idea: misjumps.

I'm working under the assumption that when a ship jumps, it emerges from jump-space with the same velocity that it had when it entered it, and that the astrogator has at least some control over the ship's post-emergence orientation (with respect to some coordinate system or another). I'm also assuming, however, that a misjump not only causes an unpredictable point of emergence, but also an unpredictable post-emergence orientation. A misjumping ship might, for example, enter jump-space heading to Coreward, and emerge heading to Rimward.

Ordinarily, this wouldn't be a serious problem -- but if you're travelling at a significant fraction of the speed of light, a post-misjump course correction could involve months, or even years of braking and acceleration. If, furthermore, your ship is absolutely dependent upon detatchable external boosters to reach its ram-scoop's "minimum working velocity," then a single misjump could bring the entire voyage to a premature end.

If you're planning a voyage of a couple of thousand parsecs, and know that despite redundancy and onboard maintenance facilities the poor jump drives are going to be suffering, betting everything on not making one misjump is probably unwise.

The jump-capable ram-scoop starship is such an incredibly elegant concept -- am I being totally over-cautious in rejecting it? Perhaps I am. After all, scooping unrefined fuel from gas giants is pretty dangerous, too (the difference, I suppose, is that the danger isn't quantified in the rules -- but naval architects and mission planners are undoubtedly well-aware of the risk, and might take it a lot more seriously than the average Traveller player).

 

[TheDS]

No jumps cause change of N-space vectors; whether they are jumps or misjumps, the ship is always going the same way at the same speed. (Unless there is something in CT or T20 that says different, and then I would treat it like "jump-masking" - pour gasoline over the fool that suggested it and toss lit matches at him.)

Regardless of how you get there, the stars are going to be going at a different rate of speed than the ones you start from. This could be a huge difference. You're going to want to carry a good thruster anyway.

If this is in the Interstellar War era, it's highly likely that the drive of choice will be the fusion rocket, which couples very nicely to a Ramjet. It sips fuel and gives a heap of thrust. Take the MW output of your favorite fusion reactor and multiply it by 20 for tons of thrust per kl of drive. Mass is also based on the reactor. Fuel comsumption will be a horrendously large .1875g / kl of thruster, at 1% efficiency (100% efficiency would sip fuel at 1/100th that rate, or .001875g/kl.)

Whoops! That's per 1000 seconds, so for an hour of thrust, multiply by 3.6.

Magnetic scoop size is going to be based on how much surface area you need to sweep per second to pick up that much hydrogen. Interstellar hydrogen is about 1 per cubic centimeter on average, about half that in OUR neck of the woods, and considerably less intergalactically. The faster you go, the smaller your field can be, because you'll be sweeping the same volume per time unit.

 

[womble]

"Who tends the tender?"

The other tender of course...

The problem with having a ship be its own tender is that some things need to be done from outside... if the colony/exploration ship were its own tender you'd need to have two very large multipurpose ships to be able to fully maintain each other. I suppose you could make a design space allowance for permitting a ship access to its own external features, but that's inefficient. If you have two specialised tenders that's enough (barring casualties) repair capacity to look after a fleet of other ships.

If the explorer is big enough to be a jump-carrier, all the subsidiary ships can be built without jump drives.

 

[TKalbfus]

I'm working under the assumption that when a ship jumps, it emerges from jump-space with the same velocity that it had when it entered it, and that the astrogator has at least some control over the ship's post-emergence orientation (with respect to some coordinate system or another). I'm also assuming, however, that a misjump not only causes an unpredictable point of emergence, but also an unpredictable post-emergence orientation. A misjumping ship might, for example, enter jump-space heading to Coreward, and emerge heading to Rimward.

A velocity has both a magnitude and a direction associated with it. If a starship emerges heading the same speed, but in a different direction, it has a different velocity.

Ordinarily, this wouldn't be a serious problem -- but if you're travelling at a significant fraction of the speed of light, a post-misjump course correction could involve months, or even years of braking and acceleration. If, furthermore, your ship is absolutely dependent upon detatchable external boosters to reach its ram-scoop's "minimum working velocity," then a single misjump could bring the entire voyage to a premature end.

Braking is easy with a magnetic ramscoop, if fact you would need to fire your maneuver drive just to keep the ramjet going at the same speed as it will have a natural tendency to slowdown as it displaces alot of interstellar hydrogen as it plows through space. You could even bring the ramjet to a complete stop with this method, using no manuever drive, by heading toward a star. The stellar wind from the stars atmosphere will push the ramjet away.

 

[savage]

Why would you want 2 ships bobbing next to each other in space trying to fix things.

The key would be build the vessel as a portable starport/colony vessel. It needs to able to manufacture parts and carry the tools to do the repairs. If that means gantry structure to attach to the outside of the hull, then fine.

It doesn't need to be a tech level behind because the worlds tech level should be at a stable average.
For those that have worked with technology... we don't always have last years tech 100% perfect. We often move on because there is something better, faster, cheaper.

I built a 10million ton Mobile starport as an experiment to this end within the rules. It would have portable colony ships, materials for working on smaller vessels, the ability to repair itself, powerplant fuel for 1 year, and a small military contingency.

As the exploration vessels plunge into the sector the ship orbits a world setting up a colony or two. Smaller vessels examine local systems, surveying and being certain they were avoiding building on someone's turf. Meanwhile, other vessels can run errands on an irregular basis between the ship and the home worlds...

Well this all works if the intent is to build a corridor (perhaps the the coreward exploration).
The smaller exploration vessels would have self-repair facilities and materials onboard as well. I put a mobile 10mt starport together a little bit ago with 100kt colony landers and it would work fine in traveller.

Of course, this all hinges on intent. If we're trying to build a new wheel that is a different thing.

Savage

 

[marginaleye]

Why would you want 2 ships bobbing next to each other in space trying to fix things.

The key would be build the vessel as a portable starport/colony vessel. It needs to able to manufacture parts and carry the tools to do the repairs. If that means gantry structure to attach to the outside of the hull, then fine.

If the colony ship is going to be equipped with a hydrogen ram-scoop then it doesn't need to be streamlined enough to skim fuel from gas giants. An unstreamlined "dispersed structure" hull (which is half-way to the "gantry structure" you're suggesting) would be just fine.

Is there any reason that workers in pressure suits couldn't crawl around on hull of a starship travelling through interstellar space at, say, a tenth of the speed of light? Yes, there is the threat of dust particles, but I vaguely recall that they could be ionized, or otherwise given an electric charge, at a distance, and then electro-magnetically deflected away from the ship, using the same hardware used to gather fuel.

I believe Arthur C. Clarke suggested "armoring" the bows of starships with a ablative "shields" of ice -- if the diameter of the shield was slightly greater than that of the rest of the ship's hull, anyone doing extra-vehicular repair work would be protected, too.

I'm envisioning a far "quicker-and-dirtier" mission than you seem to have in mind, but I think we have much the same general idea.

 

[salamander]

Originally posted by Savage:
Why would you want 2 ships bobbing next to each other in space trying to fix things.

Just curious: what would cause ships to "bob" in space, IYTU?

 

[savage]

Quick and dirty? Well depends if your talking Traveller or not. If not this should be in random static. If we are then I recall discussions suggesting that ram jets would have to be kilometers across to suck in enough materials...

Regarding repairs...basic repairs can be accomplished by assembling and attaching a girder system (shielded by reflec, kevlar,...whatever) to the outside of the hull at pre-specified points.
The mastering of grav plating must have alternative products throughout the engineering industry (boots, etc...) that would make such work doeable. I see no alternative to stopping the vessel to accomplish major overhauls.

I was thinking in mind of the Zho effort to reach coreward... and the discussions with Marc about how that would be accomplished.

If we're in the scifi realm I just don't see ram jets as lower maintenance...or any reason not to fuel scoop.

Savage

 

[savage]

Wasn't quite finished... I put my design for a major colonization/exploration effort on my website as the columbus mobile starport. I could probably tweak it more but that's the general concept. It would take a major interestellar govt to afford such an effort (the Zho, Regency or Imp.).

If the entire goal is an exploration ship and ram jets are necesary I suggest doing a FFS based design.

Savage

 

[Drakon]

To suck in enough material for an interstellar ramjet, the scoops have to be on the order of 100,000 kilometers in radius. Very large.

As to tenders, something occured to me. The problem is that to overhaul ships from time to time, you essentially need to take them apart and put them back together. For naval vessels (I'm ex-Navy so I tend to think along those lines) you need a drydock large enough for the ship.

For a space vessel in deep space, there is another solution. It might sound kind of silly, but I think it will work, provide an environment to remove ship's components, and replace them, safely, without bulky spacesuits and all their attendent hazards.

A very large plastic baggy.

Essentially, take a large balloon, put the smaller vessel inside and inflate it. Instant dry dock. Now your workers can do whatever they need to all over the ship without worrying about decompression.

Mount the package on the hull of your tender. Extend scaffolding and cover with flexible plastic material, leaving one end open. Fly smaller vessel in, seal, press up. Commence repairs.

Once done, evacuate the "dry dock", open, release the vessel, and pack the "dry dock" back against the hull of your tender.

What do you think?

 

[Whipsnade]

Drakon wrote:

"To suck in enough material for an interstellar ramjet, the scoops have to be on the order of 100,000 kilometers in radius. Very large."


Sir,

There's also trouble with the region of space surrounding Sol. It seems that we're in a bit of a 'bubble'; a bubble hundreds of light years wide, that contains less bits of interstellar material than the average. Even if you could project the Bussard's 'wings', our neighborhood has has precious little for it to scoop.

"As to tenders, something occured to me. The problem is that to overhaul ships from time to time, you essentially need to take them apart and put them back together. For naval vessels (I'm ex-Navy so I tend to think along those lines) you need a drydock large enough for the ship." [snip of an excellent proposal] "A very large plastic baggy."

"What do you think?"

I like it. Like you, I too have spent time in shipyards as a 'visitor', 'yardbird', and 'tech rep'. I'd add a few extra bits to your baggie idea though; internal scaffolding for workers and equipment, external hard panels for micrometeorite protection and the occasional bumps from small craft, modular locks for personnel, tools, parts, etc., and lots and lots of pressure tight tool cribs, changing rooms, chow halls, medical bays, etc.

All of these extras would be made up of smaller, interchangeable components. The tender would carry them all as part of her normal load out. The tender would sidle up to the ship requiring repairs and quite literally spend the first few days building a 'dry dock' (air dock?) around her. Once the job is done, the dry dock is disassembled only to be rebuilt around the tender's next job.

For simple jobs, inflated 'sausages' may be attached to the vessel's hull over the area in question.

Sincerely,
Larsen