[Spaceships] Million Merchant Marathon

[Agemegos]

Originally Posted by scc

Atmosphere or lack there of is more a matter of capturing said atmosphere, Titan is only a bit bigger then our moon and has a greater atmospheric pressure then Earth.

Titan is 48% larger than the Moon. On the other hand it is less dense. Taking one thing with another, Titan's escape velocity is 2.64 km/s, whereas the Moon's is only 2.38 km/s. That's a small difference, but Titan is also a lot colder than the Moon. That means that the gas molecules in its atmosphere move more slowly, and therefore that fewer reach escape velocity.

Using the formulas in GURPS Space, Titan's black-body temperature is 90 K and its minimum molecular weight retained works out to 26.9 a.m.u. Whereas the Moon's black-body temperature is 278 and its minimum molecular weight retained works out to 102.5 a.m.u. The molecular weight of nitrogen gas is 28 a.m.u. So that's why Titan has retained nitrogen whereas nitrogen would escape fairly quickly from the Moon.

[Anthony]

Originally Posted by Agemegos

So that's why Titan has retained nitrogen whereas nitrogen would escape fairly quickly from the Moon.

Note that "fairly quickly" means "quickly on a geological time frame"; 2.38km/s is still pretty far down the velocity distribution tail for atmospheric gases. Estimates I find online are that it you could get an atmosphere that lasted a thousand years or thereabouts.

[scc]

Originally Posted by Fred Brackin

It's obvious that nitrogen is desirable as an atmospheric dilutant anywhere they don't have it but what does isolating it on Venus and then getting rid of it have to do with the atmosphere of Venus? That's 95% carbon dioxide.

I've seen proposals that capture the carbon and turn it into many many miles tall cooling towers of diamonoid (pumping heat from the lower atmosphere to the upper where it is more easily gotten rid of).

You're probably going to need the nitrogen on Venus to make bio-mass when it cools enough.

By contrast the moons of Neptune are very unlikely to e terraformed and you can mine the solid nitrogen with cryogenic nanites or aomething like that.

Because the nitrogen in Venus' atmosphere alone gives it an atmospheric pressure 3 times that of Earth's, so if I want an Earth normal atmosphere on Venus, a lot of that has to go.

As for cooling Venus, I'm taking the sunshade approach, once it's complete it seems like it'll take 70 years for the CO2 in it's atmosphere to liquefy.

You might be right about the bio-mass bit but.

Originally Posted by Anthony

The simplest option for Mars is to head out to the Kuiper belt or Oort cloud (depending how patient you are; further out = less delta-V but more time) and start kicking comets towards Mars. Mostly what this will get you is water, but you need a thousand times more water than you need nitrogen, so the ammonia content of the comets should do the job.

Scooping up the atmosphere of Venus won't do you any real good, because it's not made up of the things you need anyway; it's mostly carbon dioxide, which isn't what Mars needs. Venus is a ridiculous mega-engineering project, far beyond the scope of Mars, but if you're really dedicated to doing it you want to deliver large amounts of water, re-spin the planet, restart tectonics so you can bury a lot of the CO2, and give the entire planet a sun shade. You might be able to start in on that by whacking it with a substantial planetoid, assuming you don't mind waiting a million years for it to be habitable.

The CO2 is actually useful because the carbon will be needed for creating biomass and the excess water can be combined with hydrogen imported from Saturn to make water. I expect that this plan will involve starting soil conditioning really early.

Originally Posted by Agemegos

Titan is 48% larger than the Moon. On the other hand it is less dense. Taking one thing with another, Titan's escape velocity is 2.64 km/s, whereas the Moon's is only 2.38 km/s. That's a small difference, but Titan is also a lot colder than the Moon. That means that the gas molecules in its atmosphere move more slowly, and therefore that fewer reach escape velocity.

Using the formulas in GURPS Space, Titan's black-body temperature is 90 K and its minimum molecular weight retained works out to 26.9 a.m.u. Whereas the Moon's black-body temperature is 278 and its minimum molecular weight retained works out to 102.5 a.m.u. The molecular weight of nitrogen gas is 28 a.m.u. So that's why Titan has retained nitrogen whereas nitrogen would escape fairly quickly from the Moon.

The Moon lacks an atmosphere more because it formed so late in the development of the Solar System then anything else.

[Agemegos]

If the Moon had formed with a thick atmosphere it would have lost it to Jeans escape long before now, and if it were provided with a nitrogen-oxygen atmosphere that atmosphere would evaporate to space in a millennium or so. The example of Titan doesn’t indicate that the Moon would be able to retain a thick nitrogen atmosphere, because the Moon is much hotter than Titan.

[scc]

Originally Posted by mlangsdorf

Okay, what was your original, gaming related question? You seem to have this all worked out to your satisfaction.

I want to know if people think it would make for a good game, I'm not sure it last beyond one or two sessions, but it's repeatable and there are other places to go in the system and do the usual Traveler inspired tramp freighter things

Originally Posted by johndallman

How are you planning to lift all that mass to Venus orbit? You'd have to speed up Venus' rotation a lot to let you use orbital elevators.

Originally Posted by scc

Um, no rockets, either a mass driver to increase rotational speed to reactionless drives tailored to produce space fighters (They have a top speed).

Originally Posted by Varyon

How are you seeing this marathon work? Are we talking a race to see who goes from Venus to the Moon fastest with everyone starting in Venus' orbit? A staggered race where you just track how long it takes each vessel for a single trip? A variant of one of the previous where how much mass of nitrogen the vessel is transporting is factored in? A "race" where victory goes to the vessel that transports the most nitrogen to the Moon during the "nitrogen transport" phase of the terraforming project? Something else? And do you see the Mars project involving a separate race, or would it be something like the above where transporting to Mars instead of the Moon is worth more points?

Yes an actual race, the races by clipper ships to bring tea to England was on my mind when I came up with this. The event is annual and the first across the line wins. Vessels get around by Mag-Sail assisted by particle accelerator stations so there's something of a starting whistle when that fires up but starting early is allowed (Because it doesn't automatically give you an advantage). At this point I'm not sure then carting stuff to Mars would begin, it could start at the same time or later on, I'm not sure.

Originally Posted by whswhs

The pressure part makes sense. Atmospheric pressure is the weight of atmospheric gases, which is the mass of those gases times the acceleration of gravity. The moon has 1/6 g, so if you have six times as much atmosphere, you'll have the same pressure. (The scale height is inversely proportional to gravitational acceleration, so it will be six times as great.)

But with the lower gravity the atmosphere will escape far faster.

I calculated how much would be needed based upon Titan's atmospheric pressure.

[Anthony]

Originally Posted by scc

I want to know if people think it would make for a good game

Running bulk freighters is not in general going to be an interesting game, though it can be the backdrop for something more exciting.

[Fred Brackin]

Originally Posted by scc

I want to know if people think it would make for a good game, I'm not sure it last beyond one or two sessions, but it's repeatable and there are other places to go in the system and do the usual Traveler inspired tramp freighter things

.

I'm having trouble seeing a place for mag-sails and any reactionless drive usable for heavy lifting in gravity wells like that of Venus. Even oif the reationless drive has a speed limit like 8 miles per second (relative to what?) drifting at that speed for free compared to the trouble and expense of mag-sailing looks pretty attractive.

It's also one of those "Space" things where you ask "Why are there humans involved in this?".

Races are also pretty hard to make into actually interactive rpg stuff. It was one of SJ's genius moments when he decided in Car Wars to sideline the going in circles and just have the cars shoot at each other.

It's also a problem that a solar system government big enough to be funding (and presumably supervising) this sort of terraforming will be squashing any Player Character shennaigans.

Of course,a society wealthy enough to be able to afford this sort of thing usually does not have that much use for terraformed planets.

[scc]

Originally Posted by Anthony

Running bulk freighters is not in general going to be an interesting game, though it can be the backdrop for something more exciting.

Like my races, yes? But there's other things to do both in conjunction with the race (Some other cargoes need hauling and there's spare space to haul them, some are government, some are private, plus people need to travel, there's also speculative trade, many goods, even basic ones, aren't made off Earth) and there's a few other places to visit.

Originally Posted by Fred Brackin

I'm having trouble seeing a place for mag-sails and any reactionless drive usable for heavy lifting in gravity wells like that of Venus. Even oif the reationless drive has a speed limit like 8 miles per second (relative to what?) drifting at that speed for free compared to the trouble and expense of mag-sailing looks pretty attractive.

Mag-Sails provide some nice cinematic and game-play opportunities but they can also accelerate to higher velocites then the reactionless drives. Also said drives are both capable of boosting said fighters into orbit while being unable to accelerate them faster then WW2 fighters, don't think about this contradiction too much.

Originally Posted by Fred Brackin

It's also one of those "Space" things where you ask "Why are there humans involved in this?".

Probably

Originally Posted by Fred Brackin

Races are also pretty hard to make into actually interactive rpg stuff. It was one of SJ's genius moments when he decided in Car Wars to sideline the going in circles and just have the cars shoot at each other.

It's more in the setup, the race is probably decided in the launch from Venus, but it isn't going to involve moving pieces on a map or anything.

Originally Posted by Fred Brackin

It's also a problem that a solar system government big enough to be funding (and presumably supervising) this sort of terraforming will be squashing any Player Character shennaigans.

No system government or even planetary government. Project through the UN pushed by CANZUK and EU mainly as a jobs thing.

Originally Posted by Fred Brackin

Of course,a society wealthy enough to be able to afford this sort of thing usually does not have that much use for terraformed planets.

They are unlikely to be that wealthy when they start.

[Anthony]

Originally Posted by scc

Like my races, yes? But there's other things to do both in conjunction with the race (Some other cargoes need hauling and there's spare space to haul them, some are government, some are private, plus people need to travel, there's also speculative trade, many goods, even basic ones, aren't made off Earth) and there's a few other places to visit.

In my experience running games, neither racing nor mercantile activity makes for a good game, other than maybe the very occasional theft or sabotage storyline.

[mlangsdorf]

Originally Posted by scc

I want to know if people think it would make for a good game, I'm not sure it last beyond one or two sessions, but it's repeatable and there are other places to go in the system and do the usual Traveler inspired tramp freighter things.

I have to confess, when I did the prep work for my tramp freighter game, it didn't occur to me to figure out the economics of terraforming Mars. In large part because the kind of regular, bulk freight loads involved in carrying a small asteroid's worth of N2 to Mars are pretty much the opposite of tramp freight loads.

But that's me, and my opinion shouldn't matter if you players think it is interesting. However, you asked, and I don't think it's a particularly interesting premise: what's the challenge here? Where are the opportunities for shenanigans and reversals?

As I indicated, I am currently running a tramp freighter game, and these are the things we've done:
* Intercept another tramp freighter to deliver a repossession team on board, and incidentally defend it from attack by pirates
* Smuggle 50 tons of highly enriched uranium (HEU), and deal with the consequences of the fact that the only people that are illegally transporting HEU are pirates
* carry a load of freight that the shipper neglected to mention contained genetically modified gladiator apes for arena battles, and have the apes' containment systems fall apart almost at the end of the journey and the apes get loose and start wrecking the cargo hold
* smuggle a huge load of precious metals, and fend off hijackings and pirate attacks and hijackings during pirate attacks because the PCs are bad at screening their passengers

Some of these plots have worked better than others, but they've all been entertaining. Shipping bulk N2 on Hohlman transfer orbits doesn't sound entertaining.