GT: Starports and Deep Space Stations

[DaltonSpence]

A while back I was looking for information on Traveller space stations on the Imperial Encyclopedia site and discovered the page about Jason Kemp's Deep Space Station. (BTW I noticed his id here was "Last seen Jun 4, 2018" so I hope he is okay.) It was meant as a "stepping stone" station of a J-2 Jump Bridge traversing the Lesser Rift in the Empty Quarter Sector between the Hegemony of Lorean and the Third Imperium. I noticed some of the design specs seemed a bit odd but put it up to having GURPS Traveller: Starports (T:ST) as my only guide to starport design and thought he might have used rules from a different version of Traveller. (I looked among my CT books but found nothing like that.) I was going to try making a from scratch design using T:ST rules when I realized what was really bugging me.

The Deep Space Station supports thirty-eight small 100-dton hangers and seven standard 800-dton hangers to serve as ship berths.

That was when I realized the only 100-dton starships I knew of were Sulieman-class Scout/Couriers and Sulieman II-class Seekers and while they were both J-2 neither has much commercial potential. The smallest J-2 Far Trader I'm aware of is the 200-dton Empress Marava-class and most other commercial ships are larger than that. Standard 800-dton starport berths could be used for some of them but the smaller 100-dton size berths seem more suitable for smaller auxiliary support craft and really shouldn't be assigned by the SPA formula for berthing starship traffic on T:ST p.74. (There must be a reason the SPA considers the 800-dton size starport berth "standard".) I'm not saying 100-dton berths wouldn't be useful but should be assigned to house transfer craft needs (see the second table on T:ST p.75).

The second thing that occurred to me (actually the first but I didn't want to admit the berthing issue is the new revelation) was how the fuel reserves would be replenished. Providing fuel to these stations is a bit tricky since any jump tanker on the route would have to carry its own fuel for the return trip before allocating space for the fuel being delivered. There are three worlds that supply fuel for the stations on the Saeghvung-Turley-Exile Run:

1. Sahale (2227) which serves DSS 2225,
2. Saeghvung (2618) which serves DSS 2720, and
3. Turley (2523) which serves both DSS 2621 and DSS 2324.

The first two systems have gas giants that can be skimmed for unrefined fuel (some of which will needs to be processed for the first jump) while the third (Turley) has no gas giants but its Class V (A) starport can provide refined fuel processed from the planet's abundant (90%) water supply. While Exile (2423) is on this route it has no fuel to provide. (I don't want to repeat myself here so see this post on the SJG GURPS Traveller forum.) Now this isn't a real Starport (just a fueling station) so it's interesting to note that while there is no real reason for the passengers, crew and cargo of the transient shipping to offload, it would probably be smart to provide recreational facilities for the crew and passengers while the ship is refueling. ("Cabin fever" can be nasty on long trips.) Regular maintenance could also be handed off to station personnel during this period to give the ship's crew a bit of a break.

I have some other ideas about this but I need more data about this setting from the original source (Jason Kemp) if possible.

Dalton “So how's this for a first post here?” Spence​

 

[tjoneslo]

The hangers are there if you want to do a shirt-sleeve transfer of cargo or passengers on/off a ship. If you are doing only fuel transfers (like suggested) or don't mind having passengers traverse a docking port, you can design to manage as many ships as will fit on the exterior of the station.

Transferring cargo into/out of a ship across a vacuum can be a tricky business, as not all cargo containers are sealed and most cargo reacts badly to vacuum exposure. This is where the hangers are most important. But, as you say, most of the ships are not there to on/off load cargo. There will be some transfer for spare parts, fresh food, and the like

Or, as you speculate, there are several small craft which float out to the nearby ships to transfer passengers, cargo, and other items. How that works depends somewhat on how you want your Traveller Universe to wok.

One thing to think about is going from Sahale to Saeghvung may not be just one ship. There may be different ships that do different legs of that trip. I suspect the change at Turley would require a transfer of ships, partly because you are going across a border. Each side of that journey is handled by a different company with the expertise to cross the border into the different empires.

As for refueling the stations, I would go very large on the oilers. Design backwards from the expected traffic and have two ships with the cargo space (for full week fuel capacity) and jump fuel capability to do the double jump.

The other option is to assume there is a nearby deep space object (e.g. a comet or small planet) as a water source which can be mined for water or other hydrogen fuel source. They are very numerous (every new astronomical survey finds more of them), so building your station on, or at least near, one seems like a brilliant idea.

 

[whartung]

As for refueling the stations, I would go very large on the oilers.

At TL15, Jump 3, an oiler can carry about 20% net fuel. So, if you have a 100,000 ton oiler, it can deliver 20,000 tons. The rest is needed by the ship and for the round trip.

The lower TLs get worse. But this scales above 1000 tons, basically, anything over 1000 tons can deliver 20% tonnage as fuel (or, well, anything).

 

[Grav_Moped]

Launch the oilers to the stations using drop tanks, especially if the tanks can be recovered. Larger payload fraction that way.

 

[Grav_Moped]

The highest TL on that run is 14, at Turley/Turley (EQ2523). It has a Class A starport, but is coded Non-Industrial. Expect them to be able to maintain TL-14 logistics-support ships for the bridge easily, but those ships would have been built elsewhere.

I don't know GT build rules, so I couldn't say what that means for the needed tanker designs. (In CT, absolutely. GT? No idea.)

 

[DaltonSpence]

I've never really liked concept of drop tanks; to me they always felt like someone's bright idea of a way to cheat the system. At the very least there should be a penalty to the jump roll when you use them. Recovering used ones could be tricky and would require a specialized vessel that would accompany the tanker to the jump point. One idea I might support is an externally carried fuel blimp that could be collapsed and stowed aboard after delivery to reduce the fuel needed to go home but I have no idea how to stat this or if it could be carried through jump space. (I don't want to leave trash floating around near the station; it could become a navigation hazard.) Anyway here is the ship I designed for this; it's not fancy but it would work.

Dalton “who needs more info on the planets” Spence​

 

[McPerth]

One idea I might support is an externally carried fuel blimp that could be collapsed and stowed aboard after delivery to reduce the fuel needed to go home but I have no idea how to stat this or if it could be carried through jump space.

This idea was already discussed in this old thread. As you can see there, I will not be the one to talk against it...

 

[daryen]

The other option is to assume there is a nearby deep space object (e.g. a comet or small planet) as a water source which can be mined for water or other hydrogen fuel source. They are very numerous (every new astronomical survey finds more of them), so building your station on, or at least near, one seems like a brilliant idea.

I just want to stress this point. Space is apparently just littered with crap. I would think that somewhere in a one parsec diameter area a comet or icy body can be found. Whether the station is directly on it, or simply sends refueling ships back and forth, I have to imagine something can be found.

And if there are multiple locations (i.e. hexes) that the deep space station (i.e. calibration point) could have been located, the more justification available to say that *this* spot was chosen because of the randomly wandering cometary body.

 

[DaltonSpence]

An externally mounted fuel bladder would have to be tougher than an internal collapsible tank, maybe by doubling the collapsed size, mass and cost with the same inflated capacity and acceleration limit (1.5 G). Installing a full bladder and demounting and stowing an empty one should take the same amount of time as the installation and removal of a solid demountable tank. Draining the bladder during a jump would probably not be a good idea as it would change the geometry of the ship and might cause a mis-jump. There could be some other issues. (Should the bladder have an embedded flexible jump grid? What is the temperature of jump-space? Would the bladder need a cooling mechanism to keep it from exploding?)

As to the resources available in an empty hex, you shouldn't expect there to be anything at all just because you want there to be. The only thing you can count on is the station itself and what is brought to it. If the referee thinks differently then we have a different story and station entirely.

Dalton “half the game's fun comes from meeting its challenges” Spence​

 

[whartung]

Space is apparently just littered with crap.

But as we're learning with Earth orbit, it can be littered too much.

 

[Condottiere]

I don't think GURPS had Collectors in general availability, as that would be the go to for tankers.

There are possible issues regarding drop tanks for jump bubbles, but not necessarily for the lanthanum grid, except as possible sources for gravity generating objects near the transition point.

 

[DaltonSpence]

One thing to think about is going from Sahale to Saeghvung may not be just one ship. There may be different ships that do different legs of that trip. I suspect the change at Turley would require a transfer of ships, partly because you are going across a border. Each side of that journey is handled by a different company with the expertise to cross the border into the different empires.

You could be right. This would justify a bigger starport on Turley than I had been previously considering.

Along the Saeghvung-Turley-Exile Run, the deep space stations are identified by the designation DSS, followed by the location of the empty parsec in which it resides. For example, a rift station located in the empty parsec of Empty Quarters 2225 would be called DSS 2225. In total, the Saeghvung-Turley-Exile Run requires four deep space stations: DSS 2225, DSS 2324, DSS 2621 and DSS 2720. The pair rimward of Turley were constructed within the Third Imperium and are manned primarily with Imperial personnel, while the pair coreward of Turley were constructed and manned by Hegemony personnel. Details within the trade pact that create created the Deep Space Station Project requires that at least ten percent of each station be manned by personnel from the more distant polity, to insure representation from both parties.

See the History of the Deep Space Station Project​

The tricky part is how much of the cargo/passenger exchange would be done at the highport and how much at the downport? Remember this would not be an SPA facility; Turley is a non-aligned world and while both the Imperium and the Hegemony would probably contribute equal numbers of personnel to the starport's operation they would most likely cede control to the local government to ensure its neutrality. This could make it an interesting place for an adventure, particularly since any ships would have been travelling most of a month just to get there. (I really need to know more about this world than the blurb contained in its wiki entry. For example, does the "Verrada Turley Foundation" control its class 8 Civil service bureaucracy government?)

Dalton “Where is Jason Kemp when you need him?” Spence​

 

[DaltonSpence]

Okay, it looks like I may have to design a new jump tanker just for Turley. (Now if only I had something more recent than the ancient (2000) GURPS Traveller Ships program by Thomas Bont to do it with. ) So I'm thinking a 2,000-dton hull (unstreamlined since it won't be skimming gas giants), a 2,100-dton fuel blimp (half the station's weekly needs) and a 820-dton drop tank (I don't like them but it would more efficient). This would quadruple the number of weekly 800-dton Oiler visits plus one more to fill the highport's needs, the drop tanks, the fuel blimps and the tanker's return fuel requirements leaving 94 tons of left over fuel per week to play with ( (7×4+1)×606-(3×4200+4×(820+400)) = 94 ) since tankers won't be landing at the downport to be refueled. This would reduce the jump fuel production needs of the downport by about 30%. (70 dtons of water processed an hour is still a lot but there would be a market for the LOX produced for life support.)

Dalton “Why do I get these ideas at 4 AM?” Spence​

 

[DaltonSpence]

To be honest the idea of "fuel blimps" intrigued me since the name implied they might be collapsible and storable in a starship's spacedock or cargo area. When I went to check my references though the only ones I found were in GT: Starports and only a few of those. Has anyone ever heard of them elsewhere in Traveller?

Dalton “afraid his bright idea has been shot by a canon” Spence​

 

[whartung]

I've talked about having a fueling operation where you have skimmers at the gas giant loading up fuel canisters (fuel blimps here) and just pushed around the system with tugs. The tug accelerates the canister, pushing it inwards towards the main system, lets it fly, and then another tug captures it and delivers it to wherever. Doesn't really matter where the refinery is.

I even had designs and worked out the costs -- a large enough corporation would save money using a scheme like this to fuel their ships than paying the 500Cr per ton for refined fuel, but it has to be large enough to pay the startup costs along with the ongoing maintenance.

But a 10,000 dTon canister filled with refined fuel is "worth" 5MCr. And the operations to build, manage, skim, refine, and wrangle that fuel is less, substantially less, than 500Cr per ton. So, it pays off.

 

[DaltonSpence]

The situation on Turley would be a bit different. There are no gas giants in that system with all the hydrogen being taken from the planet's oceans. I was looking for a collapsible fuel blimp that a starship could carry to a Deep Space Station 2 parsecs away and after delivering the fuel could collapse and stow aboard the starship for the return trip. This would save jump fuel bringing back the volume of an empty tank. Could such a blimp be constructed by GURP Traveller: Starships rules?

Dalton “I always crush my empty pop bottles for recycling” Spence​

 

[whartung]

TNE has rules for Collapsible Tanks, Drop Tanks, and Collapsible Drop Tanks.

Collapsible tanks are Cr100 per cubic meter of fuel (1400 per dTon), and take 5% to store. Drop Tanks are Cr200 per cubic meter, but are just rigid tanks. Collapsible Drop Tanks are Cr500 per cubic meter and store at 25%.

Since you're looking for a "free standing" fuel bladder, rather than thinking "blimp", I think "zeppelin" is more appropriate. And by that I mean something with some kind of rigid scaffolding to support the structure.

Deployable, Free Floating, Zero-G Fuel Bladder: Cr200 per cubic meter, collapses down to 10% for storage and transfer. The structure is designed to reinforce and contain the enclosed fuel bladder, and does not have the strength to be moved once filled. It simply can't contain the stresses of acceleration. Takes 1 hour per 1000 dTons to assemble.

 

[DaltonSpence]

Deployable, Free Floating, Zero-G Fuel Bladder: Cr200 per cubic meter, collapses down to 10% for storage and transfer. The structure is designed to reinforce and contain the enclosed fuel bladder, and does not have the strength to be moved once filled. It simply can't contain the stresses of acceleration. Takes 1 hour per 1000 dTons to assemble.

Would taking such a thing into Jump-space be considered "acceleration"? I assume the framework has mass connected to its surface area; I need that to define the GT: Starships module for it.

Dalton “crossing design systems is always painful” Spence​

 

[whartung]

Technically, Jump is not acceleration. But at the same time, I think a jump capable "blimp" would be different since it would need to have the jump grid built in to it.

At that rate, honestly, I'd go with the collapsible drop tanks, disassemble them at the destination, and bring them back in the hold.

 

[Condottiere]

1. Rules are a little fuzzy regarding transition, beyond the obvious ones.

2. Material is speculative as to whether anything not metallic can be used, otherwise vacuum proof tarpaulin should work.

3. Speculatively, use the external metal skeletal framework of the zeppelin to support the lanthanum grid.