How close are orbital starports?

[steve98052]

. . .
One could call such a facility and express spaceport.
. . .

Yeah Buddy! You are right on target, and those are great details! New components assimilated, now officially part of MTU.

I'm flattered, and glad the idea is useful.

I would add the express spaceports are uncommon, and restricted to authorized ships.

Here's an example of how they might be used:
Worlds "A" and "B" are jump-7 apart, and have huge passenger traffic between them.

Top-paying passengers board a shuttle on A to the express spaceport, and board luxurious staterooms in a module with 100 staterooms, 100 dtons of high passenger space, a dedicated power plant for life support, and little else. There they await a Jump-4 module carrier, and when it arrives in system, a high-G tug transports the module to the carrier, other tugs pull priority cargo, and high-G fuel tankers refuel the carrier. The carrier is over-staffed in engineering so it can do its every-jump routine maintenance rapidly. It jumps out to an in-between world in less than a day.

The modules from the Jump-4 carrier are unhooked while high-G tugs haul modules from the express spaceport, returning with the modules from the carrier. It's checked up, refueled, and hooked up with more modules.

The modules from A wait there until a Jump-3 module carrier arrives, and the process continues. Arriving at B, the modules are unhooked, and tugs haul them to the express spaceport, where they're transferred to shuttles, which take them to the starport.

 

[BigDogsRunning]

. . .
One could call such a facility and express spaceport.
. . .

Yeah Buddy! You are right on target, and those are great details! New components assimilated, now officially part of MTU.

I'm flattered, and glad the idea is useful.

I would add the express spaceports are uncommon, and restricted to authorized ships.

Here's an example of how they might be used:
Worlds "A" and "B" are jump-7 apart, and have huge passenger traffic between them.

Top-paying passengers board a shuttle on A to the express spaceport, and board luxurious staterooms in a module with 100 staterooms, 100 dtons of high passenger space, a dedicated power plant for life support, and little else. There they await a Jump-4 module carrier, and when it arrives in system, a high-G tug transports the module to the carrier, other tugs pull priority cargo, and high-G fuel tankers refuel the carrier. The carrier is over-staffed in engineering so it can do its every-jump routine maintenance rapidly. It jumps out to an in-between world in less than a day.

The modules from the Jump-4 carrier are unhooked while high-G tugs haul modules from the express spaceport, returning with the modules from the carrier. It's checked up, refueled, and hooked up with more modules.

The modules from A wait there until a Jump-3 module carrier arrives, and the process continues. Arriving at B, the modules are unhooked, and tugs haul them to the express spaceport, where they're transferred to shuttles, which take them to the starport.

LIkely the Express Spaceports would be owned and operated by particular passenger lines. there wouldn't be any need for random freighters to stop there, they would likely have facilities to support ships of their line. Like a Greyhound bus station. independent tour buses don't pull in there to fuel up or load/unload passengers.

 

[phavoc]

LIkely the Express Spaceports would be owned and operated by particular passenger lines. there wouldn't be any need for random freighters to stop there, they would likely have facilities to support ships of their line. Like a Greyhound bus station. independent tour buses don't pull in there to fuel up or load/unload passengers.

Due to the cost of running a spaceport like that I don't see individual lines having their own spaceports. Plus passengers would want the flexibility of arriving on one liner and then taking another to their next destination. It just makes more economic and logical sense to have share facilities - much like airports are today.

 

[baithammer]

Not to mention the high rollers wouldn't bother with public transport options, they tend to go with their own private ships.

 

[BigDogsRunning]

LIkely the Express Spaceports would be owned and operated by particular passenger lines. there wouldn't be any need for random freighters to stop there, they would likely have facilities to support ships of their line. Like a Greyhound bus station. independent tour buses don't pull in there to fuel up or load/unload passengers.

Due to the cost of running a spaceport like that I don't see individual lines having their own spaceports. Plus passengers would want the flexibility of arriving on one liner and then taking another to their next destination. It just makes more economic and logical sense to have share facilities - much like airports are today.

There are high rollers, and there are high rollers. If you can afford you’re own yacht, you are in a different class than people traveling high passage.

Maybe it would depend on the line, and how much traffic they have through a particular system. Maybe they build standardized modular stations, and ship them out to where they need to go. Perhaps at the high volume ports you would see a purpose built station, or a wing of a public station, designed for the liners. Staff would know roughly when the liners were due in system, and have some warning after they arrive, but prior to docking. Much like cruise lines today.

 

[Condottiere]

I heard of an elderly woman who sold her house, and bought a life time supply of cruise ship tickets.

Our equivalent would be Traveller Aid Society members who get a High Passage ticket every two months, and use of facilities at probably a reasonable cost.

 

[phavoc]

There are high rollers, and there are high rollers. If you can afford you’re own yacht, you are in a different class than people traveling high passage.

Maybe it would depend on the line, and how much traffic they have through a particular system. Maybe they build standardized modular stations, and ship them out to where they need to go. Perhaps at the high volume ports you would see a purpose built station, or a wing of a public station, designed for the liners. Staff would know roughly when the liners were due in system, and have some warning after they arrive, but prior to docking. Much like cruise lines today.

Meh, I don't see any reasoning that would alter the economic models of the future beyond the models of today. As we know from Traveller, operating any spacecraft or space station isn't a cheap thing to do. Even companies awash in money don't necessarily fritter it away without a good reason (and a way to make more money). Due to the vagaries of jump space you have a fairly large window of arrival times, then the ship has to move to the station. Time will always be a factor. Putting the station out towards the 100D limit means quicker transit times for the ships, but there's more to costs than just that. And there's the time it takes to actually get off the ship. It takes many hours to clear a ship of it's passengers. And stations at the 100D limit are still subject to planetary laws regarding control, so people arriving will still need to go through customs - whatever those customs controls are for that planet.

 

[AnotherDilbert]

100D stations have some problems:

You only save a few hours out of a ~180 h trip, so the shipping companies will not pay all that much. Operating space stations is not cheap.

Ships come in from many directions, so we need many 100D stations to catch most traffic.

Unless you depart in the same direction as you came from you might not save any time, since you may have to manoeuvre around the jump shadow of the planet anyway.

 

[phavoc]

100D stations have some problems:

You only save a few hours out of a ~180 h trip, so the shipping companies will not pay all that much. Operating space stations is not cheap.

Ships come in from many directions, so we need many 100D stations to catch most traffic.

Unless you depart in the same direction as you came from you might not save any time, since you may have to manoeuvre around the jump shadow of the planet anyway.

All valid points. If it were tracked more closely, the position of the station would make a distinct difference, but the game doesn't do that. There are different advantages/disadvantages to placing the station above/below the system plane, trailing, or leading the planet, or along the inner/outer system plane.

Ships would be able to jump directly to a single station as long as it's location was known. They'd simply set their destination to be at the 100D limit and they could easily rendezvous with the station. Not any harder really than emerging from jump space at a planet light years from where you started.

 

[NOLATrav]

I recall reading somewhere that local planetary law ends at 10 diameters from the surface, at which point Imperial law takes precedence. That's what I've been using IMTU for highports, customs, etc etc. It's enough of a buffer zone to mitigate surprises/attacks and it allows the big haulers to shave a few hours off a trip. Orbit/dock at the highport for inspection, cargo/pax offloading, etc then be on your way. Making planetfall usually requires a visa of some sort, generally pretty cheap and easy unless you want to land your ship.

Systems without highports generally use cutters and shuttles based around a 10-60D flight zone but poor/low tech/troubled worlds obviously may not.

Also, I use three diameters as geo-sync orbit so that puts commerce and space traffic well away from any satellite networks, low-orbit stations, etc.

Works great.

 

[Condottiere]

It's a grey area between ten and a hundred diameters.

Cooperative and joint patrols.

 

[paltrysum]

Ships come in from many directions, so we need many 100D stations to catch most traffic.

I would argue that it isn't the vagaries of where an astrogator chooses to arrive in a system, so much as the unpredictability of jump durations. Given that each starport has a predictable orbital period, shouldn't the location of each starport be predictable at any given moment, too? Seems to me there would be a database with this information so that immediately when coming out of jump, the ship's astrogator will know the nearly exact location of the starport based on the mathematical data in the ship's Library program. Starports as presented in MgT2 High Guard have manuever-0, so they do move slightly based on various factors, but that would be updated, too, at least on well-travelled worlds. The unpredictable length of a jump, however, means you don't know when and hence where you'll be when you leave the jump envelope.

Where this might completely fall down is the Void or other frontier systems. Who knows what factors might precipitate starport movement? Piracy, rogue celestial bodies, dictatorial whim? Especially on less-travelled paths, things might get a little unpredictable.

 

[AnotherDilbert]

I would argue that it isn't the vagaries of where an astrogator chooses to arrive in a system, so much as the unpredictability of jump durations. Given that each starport has a predictable orbital period, shouldn't the location of each starport be predictable at any given moment, too? Seems to me there would be a database with this information ...

Agreed, but you can't choose what side of the planet you exit jump since you can't jump through planets.

I imagine that you normally aim the jump directly at the planet and are bumped out of jump by the 100D limit. That way small deviations in jump time doesn't matter. For example the Earth moves at about 30 km/s around the Sun, with a 10 h deviation you will miss by ~1 million km, less than the 100D limit, so you are bumped out of jump at the 100D limit, but not in any predictable position.

Even if we normally ignore it there is not always a jump path between two planets, because at least some times of the year a sun, planet, or even moon might block the direct route.

 

[Condottiere]

Either to cheap to employ an astogator, or someone who enjoys flying by the seat of his pants.

You could try projecting one parsec over, but deliberately driving through a closer gravity well.

 

[BigDogsRunning]

I would argue that it isn't the vagaries of where an astrogator chooses to arrive in a system, so much as the unpredictability of jump durations. Given that each starport has a predictable orbital period, shouldn't the location of each starport be predictable at any given moment, too? Seems to me there would be a database with this information ...

Agreed, but you can't choose what side of the planet you exit jump since you can't jump through planets.

I imagine that you normally aim the jump directly at the planet and are bumped out of jump by the 100D limit. That way small deviations in jump time doesn't matter. For example the Earth moves at about 30 km/s around the Sun, with a 10 h deviation you will miss by ~1 million km, less than the 100D limit, so you are bumped out of jump at the 100D limit, but not in any predictable position.

Even if we normally ignore it there is not always a jump path between two planets, because at least some times of the year a sun, planet, or even moon might block the direct route.

I'm caught on a couple of different issues. Given the unpredictability of the jump duration, and the implication that the Jump entrance/exit points being stationary (whatever that means) against the universal reference frame, you have a wide margin of error on predicting the exit location from Jump.

Movement to account for: https://astrosociety.org/edu/publications/tnl/71/howfast.html
Galaxy through Universe: 2.1M km/hr
Solar system through Galaxy: 828K km/hr
Earth around Sun: 108km/hr

So, depending on the whether a planet is moving, relative to your Jump entrance point, away around its sun, or towards you around its sun, you could have up to 3,036,000 km/hr of movement to account for. Given a 10% variance on 168hrs, your exit area is an arc 102 million km long, even assuming perfect navigational information. This has always bothered me. Another thing that bothered me was, I just assumed that starships regularly jumped in above the solar ecliptic, to miss the jump shadow of the various worlds in the system. On the other hand, Jump Space doesn't actually correspond to real-space, so why would it be impacted by gravatic influences in this universe anyway? There has always been some cognitive dissonance required to make Jump drive work. I realize that the Jump mechanism was introduced to maintain the Tall-ship era in space feel, but there are problems with it that I just have difficulty working out. I tend to be pretty hand-wavy regarding technology when I run games, but at the same time, I strive for some internal consistency, and look for ways that the science would produce economic and cultural impacts.

Does anyone have thoughts regarding the Jump reference frame that resolves any of these issues? I'm assuming that someone has addressed these issues previously. Can anyone point me at a good explanation that will allow me to continue hand-waving the inconsistancies? :idea: :shock:

 

[baithammer]

The gravitational influence is the formation of the jump space exit, the exit can't exist inside a strong gravitational field.

As to the inbound jump track, have to take into account orbital bodies and if the planet is near the stars 100d limit which might limit the landing zone to a more limited area.

 

[AnotherDilbert]

Galaxy through Universe: 2.1M km/hr
Solar system through Galaxy: 828k km/h
Earth around Sun: 108k km/h

And since you carry your velocity vector with you through jump, you will exit jump with a velocity corresponding to the relative velocity of the star systems and planets.

Does anyone have thoughts regarding the Jump reference frame that resolves any of these issues? I'm assuming that someone has addressed these issues previously. Can anyone point me at a good explanation that will allow me to continue hand-waving the inconsistancies? :idea: :shock:

I can't recall any canon source that even start to address this.

The laws of conservation of mass and energy continue to operate on ships which have jumped; when a ship exits jump it retains the speed and direction that it had when it entered jump.
...
An additional complication is imposed on ships when the two star systems involved have a high proper motion with respect to each other. In that case, a ship must take into account relative velocity between the two, when computing speeds and directions.

We could possibly take this to imply that common velocity compared to the Galaxy does not matter.

 

[Condottiere]

Generally speaking, astronomical information should be pretty precise in the immediate interstellar neighbourhood.

 

[baithammer]

Not with communications having to rely on the deviation of x-boat jumps.

 

[Linwood]

That could be a reason for regular re-surveys of known systems - to improve accuracy of jump calculations.