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Old 08-04-2022, 05:51 PM   #1
scc
 
Join Date: Mar 2013
Default [Spaceships] Million Merchant Marathon

So I'm working on stuff for a setting that has Earth going through terraforming Venus, The Moon, and Mars. It's this terraforming bit that kind of interests me for the moment. To terraform the Moon I need to 2.4e15 tons of nitrogen from Venus to the Moon, moving about that much to Mars is probably also a good idea as well.

Now this number is big, so that means there will be a lot of freighters moving this nitrogen, even the absurd number I give of 1 million will require something like 3 million years of ships moving gas so it's probably actually low. Now given that Hohmann transfer orbits are a thing that means that the ideal conditions for a race.

The amount of prize money isn't great, but it's on top of a contract that's specifically designed to pay your bills and it probably puts you at the top of the list for anyone other then the government (government contracts are assigned at random) looking to ship stuff to Venus.

So the government has structured things so that only family operated ships, or those that appear to be so, eligible for nitrogen shipping contracts and neither the shipping nor the race is a good way to make money fast, but it means you'll have you're foot in the door when actual competitive shipping begins. And other destinations are on offer, just not every often.
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Old 08-04-2022, 08:06 PM   #2
Fred Brackin
 
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Default Re: [Spaceships] Million Merchant Marathon

I wouldn't move those quantities of nitrogen from Venus to either the Moon or Mars and I wouldn't use rocket ships in hohman orbits.

The best alternative I can think of off-hand is to move it from the moons of Neptune where its a solid and wrap it in enough aluminum (shiny side out) to keep it from melting and also provide the conductor necessary for use in a magnetic launcher.

Titan might also be an interesting source.
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Old 08-04-2022, 08:13 PM   #3
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Can you terraform the Moon? Id be surprised if it had enough gravity to retain nitrogen.
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Old 08-04-2022, 08:22 PM   #4
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Default Re: [Spaceships] Million Merchant Marathon

At TL9, does a 300,000 ton, SM+13 advanced fusion pulse drive system that costs $7.2 billion count as a family operated ship? Because it takes 1.2e10 trips by that kind of freighter to move that amount of nitrogen.

A cheaper, SM+10 version of the design only costs $240 million, so more family friendly, but requires 3.6e11 trips. Which is a crazy high number.

But I agree with Fred. It is going to decades, if not centuries, to move that much stuff, and there's no great reason to do it with manned (or even robotic) cargo ships. Build a ridiculously huge mass driver or laser launch system in orbit around Venus and send frozen N2 payloads to the inner system on ballistic paths.
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Old 08-05-2022, 02:01 PM   #5
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Default Re: [Spaceships] Million Merchant Marathon

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Originally Posted by SydneyFreedberg View Post
Can you terraform the Moon? I’d be surprised if it had enough gravity to retain nitrogen.
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.

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Old 08-04-2022, 08:52 PM   #6
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Originally Posted by Fred Brackin View Post
I wouldn't move those quantities of nitrogen from Venus to either the Moon or Mars and I wouldn't use rocket ships in hohman orbits.

The best alternative I can think of off-hand is to move it from the moons of Neptune where its a solid and wrap it in enough aluminum (shiny side out) to keep it from melting and also provide the conductor necessary for use in a magnetic launcher.

Titan might also be an interesting source.
So I'm using Venus because I'm trying to terraform all three, Venus has too much atmosphere while the Moon and Mars have too little, either way I'm going to be moving that stuff off of Venus, might as well use to for these other terraforming projects as well.

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

Want liquid nitrogen because it's easier to handle (slightly)

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Originally Posted by SydneyFreedberg View Post
Can you terraform the Moon? Id be surprised if it had enough gravity to retain nitrogen.
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.

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Originally Posted by mlangsdorf View Post
At TL9, does a 300,000 ton, SM+13 advanced fusion pulse drive system that costs $7.2 billion count as a family operated ship? Because it takes 1.2e10 trips by that kind of freighter to move that amount of nitrogen.

A cheaper, SM+10 version of the design only costs $240 million, so more family friendly, but requires 3.6e11 trips. Which is a crazy high number.

But I agree with Fred. It is going to decades, if not centuries, to move that much stuff, and there's no great reason to do it with manned (or even robotic) cargo ships. Build a ridiculously huge mass driver or laser launch system in orbit around Venus and send frozen N2 payloads to the inner system on ballistic paths.
First off, yes I realise about the time scale.

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.

Last edited by scc; 08-04-2022 at 09:05 PM.
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Old 08-04-2022, 09:18 PM   #7
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Originally Posted by scc View Post
So I'm using Venus because I'm trying to terraform all three, Venus has too much atmosphere while the Moon and Mars have too little, either way I'm going to be moving that stuff off of Venus, might as well use to for these other terraforming projects as well.

s.
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.
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Old 08-04-2022, 09:28 PM   #8
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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.
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Old 08-04-2022, 09:46 PM   #9
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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.
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Old 08-04-2022, 10:27 PM   #10
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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.
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