Population in colonies and other tidbits

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Population in colonies and other tidbits

Postby SeraphimKnight » Sat May 31, 2014 6:43 am

I was wondering how much colonists would live on colonies? What's considered a huge/big/medium/small colony in terms of population? If there is a system with multiple habitable planets, is it standard to colonize all of them? What about fuel extraction from gas giants? Are there orbital colonies nearby? What kind of population would those have? Considering the need for a lot of traffic between planets within a single system, is it realist to think there'd be more than one transit gate and can all transit gates travel to other systems or does the size/available power have to do with it?
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Re: Population in colonies and other tidbits

Postby gusindor » Sat May 31, 2014 9:07 am

SeraphimKnight wrote:If there is a system with multiple habitable planets, is it standard to colonize all of them?

If the gain were worth the expense, sure. People colonize based on where would be good to live and where there are resources they want.
What about fuel extraction from gas giants? Are there orbital colonies nearby?

IIRC one of the four founders of the Solar Union is the Jovian Accord, which is a collective of colonies on Jupiter's many moons. I think it's safe to say that harvesting various substances from gas giants' atmospheres is a viable thing. As for colonies that are giant space-stations, it seems like it would be easier to build on the planet itself or on a moon, but if neither of those are options and the planet is really worth it, colony-satellites are probably possible.
What kind of population would those have? Considering the need for a lot of traffic between planets within a single system, is it realist to think there'd be more than one transit gate

You'd need some pretty exceptional circumstances to justify building multiple transit gates in the same system, especially just for zipping between planets. Gates are expensive, and I'm pretty sure ships can travel between planets just fine on their own.
and can all transit gates travel to other systems or does the size/available power have to do with it?

I don't think there are really different sizes of gate. If it's not big and powerful enough to send fleets of ships to other systems, it's not worth the expense of building. So smaller short-range gates might be possible, but they don't exist.
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Re: Population in colonies and other tidbits

Postby spacemonkey » Sat May 31, 2014 12:16 pm

SeraphimKnight wrote:I was wondering how much colonists would live on colonies? What's considered a huge/big/medium/small colony in terms of population?
Regarding colony sizes, you'll want to check out the discussion in this thread: Colonization in the Solar Union

SeraphimKnight wrote:Considering the need for a lot of traffic between planets within a single system, is it realist to think there'd be more than one transit gate and can all transit gates travel to other systems or does the size/available power have to do with it?
Adding to what gusindor said, yes all transit gates allow travel to others systems (that and interstellar communication are their primary functions) and no, miniature gates aren't practical. Transit limits primarily come down to economics: short transits are impractical due to the high base financial expense while super long jumps are largely infeasible due to the insane amount of power that would be required as Soren mentioned in this thread.
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Re: Population in colonies and other tidbits

Postby Soren » Sat May 31, 2014 2:06 pm

SeraphimKnight wrote:Transit limits primarily come down to economics: short transits are impractical due to the high base financial expense while super long jumps are largely infeasible due to the insane amount of power that would be required as Soren mentioned in this thread.


Edited that post for clarity. Also worth noting that it's one of the things that allows us to have 'geography' (astrography?) between systems, since jumping twice with a waystation over the same distance will use less energy than a single jump. This means some marginal planets and moons will be settled (or at minimum, play host to stations and can-cities) primarily as 'rest-stop' colonies on the way to richer, more settled ones, giving the universe a bit more texture.
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Re: Population in colonies and other tidbits

Postby SeraphimKnight » Sat May 31, 2014 7:25 pm

Thanks for the answers. Now I got more questions though!

In the colonization of planets, is the surface temperature a big factor in its colonization? Since a lot of Jovian moons have been colonized I'd think it's not a big deal. Following on that, as long as it's not something like a hadean moon, it should be relatively okay to colonize a gas giant's moons, right?

On another topic, following the reasoning that Venus is currently being teraformed, is Saturn's moon Titan being colonized? It could be an interesting venue to exploit the hydrocarbon lakes at the poles.

I know this was mentioned somewhere before, but generally where are the transit gates placed? It makes sense to place them nearest to the most colonized planet of the system, but where? A lagrangian point? Intra-lunar orbit? Near-earth orbit?
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Re: Population in colonies and other tidbits

Postby Soren » Sat May 31, 2014 7:49 pm

SeraphimKnight wrote:Thanks for the answers. Now I got more questions though!

In the colonization of planets, is the surface temperature a big factor in its colonization?


No more so than you want it to be. One of the colonies I brainstormed up a while back was a partially-terraformed Venusian world with a steambath atmosphere and seas full of purple sulfur bacteria. Others include iceballs where the atmosphere freezes out at the poles, or tidelocked desert planets around red dwarf stars. Exotic and weird environments are more fun than Oh Look, Yet Another Earth.

SeraphimKnight wrote:Since a lot of Jovian moons have been colonized I'd think it's not a big deal. Following on that, as long as it's not something like a hadean moon, it should be relatively okay to colonize a gas giant's moons, right?


Yes and yes. I love inhabited gas-giant moons (earthlike and otherwise) as a trope in science fiction, so go nuts. Mind the intense magnetic field.

SeraphimKnight wrote:On another topic, following the reasoning that Venus is currently being teraformed, is Saturn's moon Titan being colonized? It could be an interesting venue to exploit the hydrocarbon lakes at the poles.


No reason it couldn't be? The universe is open-ended so you can decide for yourself. If we haven't said yet, it means we don't have an answer.

SeraphimKnight wrote:I know this was mentioned somewhere before, but generally where are the transit gates placed? It makes sense to place them nearest to the most colonized planet of the system, but where? A lagrangian point? Intra-lunar orbit? Near-earth orbit?


Depends on the system and your personal whim. I like whims.
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Re: Population in colonies and other tidbits

Postby SeraphimKnight » Sat May 31, 2014 8:51 pm

One last question; how lengthy is intra-stellar travel? Is it realistic to say that there's a lot of traffic between planets in a given system?
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Re: Population in colonies and other tidbits

Postby spacemonkey » Tue Jun 03, 2014 3:34 pm

SeraphimKnight wrote:I know this was mentioned somewhere before, but generally where are the transit gates placed? It makes sense to place them nearest to the most colonized planet of the system, but where? A lagrangian point? Intra-lunar orbit? Near-earth orbit?
There is a little more discussion about this in the thread: What Orbit are Transit Gates Placed in?

SeraphimKnight wrote:One last question; how lengthy is intra-stellar travel? Is it realistic to say that there's a lot of traffic between planets in a given system?

In the past Joshua has mentioned this (emphasis mine):
Joshua A.C. Newman wrote:Ships meant to go between planets are more like aircraft carriers, though: huge, with lots of life support, redundant systems, artificial gravity rings, hydroponics, all that jazz. They might have the same number of people and frames onboard, but they need to live on there for months at a time.


As a point of reference, I found this information in an article about the travel time from Earth to Mars on Space.com:

Nola Taylor Redd, SPACE.com Contributor wrote:The fastest spacecraft launched from Earth was NASA's New Horizons mission, which is en route to Pluto. In January 2006, the probe left Earth at 36,000 mph (58,000 kph). The time it would take such a probe to get to Mars would be:

Closest approach: 942 hours (39 days)
Farthest approach: 6,944 hours (289 days)
On average: 3,888 hours (162 days)

As for there being "a lot of traffic" between planets, I would guess if there are valuable enough resources on the other planets there is probably frequent travel between the worlds with a ship or convoy coming or going every few days (probably would vary "seasonally" based on relative orbits of the planets) but in general the space lanes would be very empty/open. I would think the only place(s) with "heavy traffic" would be around the transit gate(s) probably requiring actual space traffic (as well as docking) coordinators to facilitate the safe and timely arrival/departure of ships on a daily or even hourly basis (not that gate transits would be that frequent but the moving of goods to and from the station's cargo facilities could be).
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Re: Population in colonies and other tidbits

Postby SeraphimKnight » Wed Jun 04, 2014 4:33 am

My understanding is that space-faring travel is at least a good deal more advanced in SC than what we have here (without being FTL or even anywhere close to near-light), so even the fastest spacecraft sent from earth in the present would be a pretty leisurely pace in MFZ. So realistically you could expect Earth-Jupiter (at closest orbit) to take around 20 days to a month and Earth-Mars to go about a week. I'd think that that's a fair estimate, but are these realistic?

All these questions are really only to make my understanding of the MFZ universe better so that I can make my own setting as coherent to canon as possible :) Thanks for all the answers by the way
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Re: Population in colonies and other tidbits

Postby spacemonkey » Wed Jun 04, 2014 12:37 pm

Well I provided those numbers as sort of a "minimum" baseline given that is what our current fastest space travel allows but let us consider if SC travel is say 4x faster on average (which doesn't seem like an unrealistic possibility):

4x faster = 144,000 mph (~232,000 kph).

The time it would take to get from Earth to Mars would be:

Closest approach (33.9 million miles/54.6 million km): ~235 hours (~10 days)
Farthest approach (250 million miles/401 million km): ~1736 hours (~72 days)
On average: ~972 hours (~40 days)

The time it would take to get from Earth to Jupiter would be:

Closest approach (365 million miles/588 million km): ~2535 hours (~106 days)
Farthest approach (601 million miles/968 million km): ~4174 hours (~174 days)
On average: ~3354 hours (~140 days)

I think the average numbers are the best ones to consider. As the planets are always in motion even launching at the closest approach won't yield those exact times as the planets will have separated some distance during the intervening travel time. Also notably, Mars has never approached Earth at that very closest distance at anytime in recorded history and only makes a close approach roughly every 26 months.

So even going with your assumption, SeraphimKnight, of roughly a week from Earth to Mars (at closest) would still yield a rough travel time from Earth to Jupiter (at closest) of almost 3 months but the averages would be more like a month's travel to Mars and just under 4 months to Jupiter. Either set of these travel times could still fit with Joshua's statement but also works with my general assumption on intra-system traffic. So not quick enough to really encourage many recreational or business travelers but short enough to be economical for the transportation of goods and people.
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Re: Population in colonies and other tidbits

Postby Soren » Wed Jun 04, 2014 1:07 pm

Consider also the Aldrin cycler, which should be more widely known. It's the interplanetary equivalent of freight rail - slow, but high-capacity and reliable. There are probably passenger accommodations as well, if not terribly fancy ones.
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Re: Population in colonies and other tidbits

Postby SeraphimKnight » Wed Jun 04, 2014 6:44 pm

Cyclers look like a neat option to use.

Alright, thanks a lot to the both of you (and also gusindor) for the answers!
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Re: Population in colonies and other tidbits

Postby spacemonkey » Wed Jun 04, 2014 7:09 pm

As an addendum to my thoughts on intra-system traffic, I thought of one other potential "heavy traffic" zone that might frequently exist: multiple colonies/settlements on stations or moons orbiting the same gas giant. If that same gas giant is playing host to the transit gate... well you could have traffic backed beyond the planetary rings. :P
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Re: Population in colonies and other tidbits

Postby SeraphimKnight » Wed Jun 04, 2014 11:29 pm

Well, the main purpose of all of these questions is for worldbuilding for my MFZ faction and the systems they occupy. I've started fleshing out what I consider their "main system", so any good ideas are welcome :)
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Re: Population in colonies and other tidbits

Postby Meaker VI » Thu Jun 05, 2014 2:37 pm

Soren wrote:Consider also the Aldrin cycler, which should be more widely known. It's the interplanetary equivalent of freight rail - slow, but high-capacity and reliable. There are probably passenger accommodations as well, if not terribly fancy ones.


Something I've read about that would be an interesting addition to this is to put regular fuel-dumps along useful orbital paths. If your society uses interplanetary travel for moving people frequently, they might invest in regular fuel-launches to support higher-speed passenger vessels. The passenger ship would plot an intercept course with one (or more) of the fuel dumps and go all-out until it gets there, refuel, and then keep going all-out until it gets to its destination. This might allow higher-G Brachistochrone* trajectories, enabling Earth-Mars trips in as little as 4 days and Earth-Jupiter in 12 days. Keep in mind though, that's really fast (you'd be burning literal tons of fuel every day), and the travel times given above are already nearly .1 G Brachistochrone missions.

*Brachistochrone trajectory = going from place to place without turning off your engines. Full burn to half-way point, flip the ship around, full burn to slow down to your destination. The most inefficient way to travel, but also the fastest. A nice side-benefit is that your ships have gravity along the direction of thrust.
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Re: Population in colonies and other tidbits

Postby grafvonbarnez » Sat Jun 07, 2014 12:11 am

Unfortunately, you're never going to even get close to a 1g (or even 0.1g) brachistochrone trajectory with anything that could probably exist in the Solar Calendar.

(Lots of math incoming!)
Say you've got an absurd propulsion system like a nuclear salt-water rocket. The given theoretical values for one are 13 meganewtons of thrust at an exhaust velocity of 66km/s. At 13MN of thrust, the largest our rocket can be to get 1g of acceleration fully loaded with propellant is ~1325 metric tons. (We could start it larger and slower and aim for an average acceleration of 1g, but once the tank was almost empty the acceleration would destroy it, and have long before killed all the passengers. Assume we can throttle the engine somehow to stay at 1g of acceleration through the whole trip.) Say we somehow manage to make the dry mass of our enormous nuclear rocket a mere 50 metric tons (33 of which are engine, giving us 17 tonnes for the body of the rocket, propellant tanks, life support, and passengers), giving us a bulky 1275 tons of fuel. The Tsiolkovsy rocket equation then gives our rocket a delta-v budget of [66,000 m/s * ln( 1325000 kg / 50000 kg)] = ~ 215,000 m/s. A 1g brachistochrone from Earth to Mars requires ~1,750,000 m/s delta-v. We'll have to hit at least 8 propellant depots along the way, refueling at speed while riding a continuous nuclear explosion. Total fuel consumption: ~10000 metric tons, including ~4000 tonnes of highly enriched uranium salts, to get maybe one person from Earth to Mars in 2 days.

If we assume a more reasonable engine technology and flight plan, it gets a lot easier but longer. If we assume, as spacemonkey wrote, SC engine technology is 4x better than current space tech, we'll end up with a theoretical propulsion system capable of just as much thrust as a chemical rocket and 4x the fuel economy (exhaust velocity or specific impulse). Current chemical rockets burning liquid hydrogen and oxygen have a specific impulse of ~450 seconds, corresponding to an exhaust velocity of ~4400 m/s. As long as the thrust is reasonably high, the exact number doesn't matter. For a low-thrust engine, the delta-v numbers get a little weird and I don't know how to calculate them.

So, if SC engines are 4x better, let's say they have a specific impulse of 1800s. That's reasonably close to a closed cycle gas-core nuclear thermal rocket, which is a decently cool engine design while not being completely ridiculous. We'll give it a dry mass (including payload and 30 tonnes of engine) of 200 tonnes, about 3 space shuttles, and a mass ratio of 4, so the total mass with fuel will be 800 tonnes. Going again to the rocket equation, [(1800s *9.81 m/s^2) * ln(800,000 kg / 200,000 kg)] = ~24000 m/s delta-v. Looking good!

The best estimate I can find of the maximum time/minimum delta-v Hohmann transfer orbit from geosynchronous Earth orbit to low Mars orbit is 4500 m/s. If we go off the Atomic Rockets table, subtracting the ~10000 m/s to take off from Earth and land on Mars, and cutting the total in half for a one way trip, we can make the I2, little over a month long trip (17000 m/s) easily. Granted, 600 tonnes of liquid hydrogen strapped to a nuclear reactor probably still isn't going to be cheap, but if you don't want to wait the 146 days for the next cycler trip and you've got the money and resources, why not?

To take that hypothetical ship further, if you're in a system without a fleet of cyclers set up, you can still get some pretty good economy out of it. If you're trying to get something from the equivalent of GEO to a Jovian moon, you're looking at about 13500 m/s of delta-v. If we trim down our rocket's delta-v budget to 15000 m/s for the trip plus course corrections and safety margin, we can get a [e^(15000/(1800*9.81)] ~ 2.33 mass ratio. Now our 200 tonne ship only needs ~260 tonnes of propellant. A 2.33 mass ratio is probably well within the range of where a cargo ship could actually be economical. If this same ship is only going the 4500 m/s seven month trip between exo-Earth and exo-Mars, we can get away with only 65 tonnes of propellant. Almost 75% of our ship can actually be ship! Ain't space cool?

As an aside, a closed-cycle gas core nuclear thermal rocket is probably a decent choice for an SC spaceship engine. It does require a little bit of hand-waving, as the thrust isn't comparable to modern chemical rockets and the engine core will, you know, be crazy radioactive. But if we say they solved the thrust problem in an unconventional way, and maybe discovered a nuclear fuel cycle that avoids some of the major lingering radioactivity problems of current nuclear fuels, it's fairly powerful, compact, and economical while still being reasonable.
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Re: Population in colonies and other tidbits

Postby spacemonkey » Mon Apr 06, 2015 4:02 pm

A little thread necromancy but I just saw this article this morning: VASIMR Rocket Could Send Humans To Mars In Just 39 Days.
Funnily enough that could take my earlier speculation from a plausible development to a possibility in our lifetimes... :shock:
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Re: Population in colonies and other tidbits

Postby Vitoria » Tue Apr 07, 2015 5:00 pm

spacemonkey wrote:A little thread necromancy but I just saw this article this morning: VASIMR Rocket Could Send Humans To Mars In Just 39 Days.
Funnily enough that could take my earlier speculation from a plausible development to a possibility in our lifetimes... :shock:


Space exploration is really amazing, I wonder how far ion propulsion will get in the next few decades.

I rememeber, when I was a kid, I saw a documentary about the concept and it sounded like something so distant and scy-fy, especially when they mentioned the TIE Fighters from Star Wars.
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