[Spaceships] Million Merchant Marathon

[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.

[mlangsdorf]

Originally Posted by scc

Using a pulse drive not only means fuel costs, which raises the cost of this whole program, which given that Earth will go through a dark age making fuel production impossible for part of this, is a big problem. Tt also goes my decision to use another method propulsion as the primary for this setting, one with some cool, or at least interesting, options.

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

[johndallman]

Originally Posted by scc

To terraform the Moon I need to [move] 2.4e15 tons of nitrogen from Venus to the Moon, moving about that much to Mars is probably also a good idea as well.

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.

[FrackingBiscuit]

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.

Freighters that transform into giant maids with vacuums.

Just need a way to get past the planetary shields.

[Witchking]

Originally Posted by FrackingBiscuit

Freighters that transform into giant maids with vacuums.

Just need a way to get past the planetary shields.

We have a WINNER!!!!

Move it to Mars at Ludicrous Speed!

[johndallman]

Originally Posted by johndallman

You'd have to speed up Venus' rotation a lot to let you use orbital elevators.

Originally Posted by scc

. . . either a mass driver to increase rotational speed . . .

Could you lay out your sequence of stages in this operation? It's a bit confusing. As far as I can tell, it goes like this:

1. Build a sunshade for Venus, let it cool enough for the CO2 to liquify.
2. Build a huge mass driver on Venus' surface, which is covered in liquid CO2 to a substantial depth. That ocean also contains enough of various acids (hydrochloric, hydrofluoric and sulphuric) to worry about.
3. Start chucking rocks off Venus to increase its rotation rate. You have to get them to at least Venus orbital velocity, through a nitrogen atmosphere that's three times as dense as Earth's. That looks rather hard. Or are you going to let Venus cool enough to freeze the CO2 and liquify the nitrogen? That may take a long time, since Venus must be expected to have radioactive heat in its core.

[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?

Originally Posted by Qoltar

That is part of the background of the Star Trek universe - at some point in the future the Moon is terraformed and has lakes on it, one of which can be seen from Earth.

-Ed C.

Schlock Mercenary also opted for a terraformed Luna. There's a bit of discussion here in the notes for the comic; apparently they spun up Luna so it wouldn't have a month-long day, and chucked enough atmosphere at it that said atmosphere is 6x as deep as Earth's, which somehow prevents it from losing much atmosphere (and also means you get atmospheric pressure around that of Earth, despite the low gravity). I'm no planetologist, however, so I can't say how realistic any of this is.

[whswhs]

Originally Posted by Varyon

Schlock Mercenary also opted for a terraformed Luna. There's a bit of discussion here in the notes for the comic; apparently they spun up Luna so it wouldn't have a month-long day, and chucked enough atmosphere at it that said atmosphere is 6x as deep as Earth's, which somehow prevents it from losing much atmosphere (and also means you get atmospheric pressure around that of Earth, despite the low gravity). I'm no planetologist, however, so I can't say how realistic any of this is.

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.

[Anthony]

Originally Posted by Varyon

Schlock Mercenary also opted for a terraformed Luna. There's a bit of discussion here in the notes for the comic; apparently they spun up Luna so it wouldn't have a month-long day, and chucked enough atmosphere at it that said atmosphere is 6x as deep as Earth's, which somehow prevents it from losing much atmosphere (and also means you get atmospheric pressure around that of Earth, despite the low gravity). I'm no planetologist, however, so I can't say how realistic any of this is.

As long as you're willing to keep replenishing it you can make it work; it will leak away but not that fast.

[SydneyFreedberg]

I suppose by the time your civilization is seriously considering terraforming the gosh-darn Moon, the fact that you’ll have to keep replenishing the atmosphere is not going to bother you…