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Interesting things to do with the solar system in scifantasy
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Mechalich
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PostPosted: Sat Feb 18, 2017 4:49 am    Post subject: Reply with quote Add User to Ignore List

Zinegata wrote:

The issue here is that the space craft and the mining colony are incredibly costly items from a capital expenditure perspective. Fishing boats used by slavers by contrast are often cheap hand-me-downs. Any reasonable business seriously trying to exploit resources elsewhere in the Solar System isn't going to put a billion-dollar craft in the hands of a couple of slaves who might consider just crashing the damn thing into the nearest rock out of spite. It's also the same reason why the process for selecting astronauts has thus far been an extremely careful process.


It's not only cost that matters, it's also danger. Jon's Law for SF Authors states very accurately that "Any interesting space drive is a weapon of mass destruction. It only matters how long you want to wait for maximum damage."

If you want some kind of nasty fusion torch that punches you up to prolonged 1g acceleration, you have to deal with the fact that your spacecraft engines are weapons of nuclear devastation that will be unable to land anywhere not capable of surviving the equivalent of a low-level nuke and that are capable of potentially accelerating to relativistic velocities and turning any ship (or just a rock with engines strapped to the side) into an unstoppable planet-shattering weapon (xkcd theoretically threw some things at the Earth really fast, reading the results gives you the idea).

This is the catch-22 of Hard SF settings - any drive system powerful enough to lower travel times sufficient to allow for interesting stories is so devastating that it mandates a draconian control regime that severely restricts interesting stories.
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FrankTrollman
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PostPosted: Sat Feb 18, 2017 9:30 am    Post subject: Reply with quote Add User to Ignore List

Mechalich wrote:

If you want some kind of nasty fusion torch that punches you up to prolonged 1g acceleration, you have to deal with the fact that your spacecraft engines are weapons of nuclear devastation that will be unable to land anywhere not capable of surviving the equivalent of a low-level nuke and that are capable of potentially accelerating to relativistic velocities and turning any ship (or just a rock with engines strapped to the side) into an unstoppable planet-shattering weapon (xkcd theoretically threw some things at the Earth really fast, reading the results gives you the idea).


You have your qualifiers backwards. A 3 billion joules per second fusion torch is capable of accelerating a mass to be a world destroying missile. But that's a jet of flame that as described is one quarter the power of the jet of flame that shoots out the bottom of a space shuttle launch. A sustained fusion torch is capable of much gentler takeoffs and landings than the short bursts of hydrogen ignition we use today.

You still probably wouldn't want to send your big capital ships up and down the Earth gravity well, because you'd be exposing your ridiculously expensive and massive ship to a lot of weather and shit that it wouldn't have to deal with in space. But the jet of flame itself is only a world destroying threat if the pilots decide to make it so a few days in advance.

Zinegata wrote:
It's two fold - an asteroid must have the rare metals and elements that you want, and it must have stuff needed to generate and renew a supply of water. Without water you can't really do a lot of industrial processes to do on-site separation of ores.


This is completely wrong. We use water based separation because it's cheap and easy to do when you have a lot of water. Gasseous centrifuging is much more effective when you have access to really good insultation - like millions of kilometers of vacuum.

Zinegata wrote:
You can get more gold on Earth if you look hard enough and are willing to invest in more expensive process


This is also not true.

BBC, on Eros 433 wrote:
In the 2,900 cubic kms of Eros, there is more aluminium, gold, silver, zinc and other base and precious metals than have ever been excavated in history or indeed, could ever be excavated from the upper layers of the Earth's crust.


Basically all we have to do is find one high metal content asteroid of medium size and it is a richer mining source of metals than all mines on the Earth's surface that have ever existed in history or could ever be built. If our society ever wants to go really crazy with metals - like building houses out of high tech ferrous foams and shit, then we need to get our hands on an order of magnitude more metal than we have right now. And that's completely available inside the solar system from just a few hyperdense rocks.

-Frank
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Mechalich
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PostPosted: Thu Feb 23, 2017 1:41 am    Post subject: Reply with quote Add User to Ignore List

In interesting news on this topic there's the discovery of the TRAPPIST system. That's a system with seven Earth-sized planets and three potentially habitable ones. Critically though, all of the seven planets are at orbital distances from 0.011 AU to 0.06 AU. That's seven systems crammed into a space considerably smaller than the orbit of Mercury (0.3-0.45 AU). Distances in the range of 0.01 AU are only ~1.5 million kilometers, which is only around 4 times the Earth-Moon distance. That's very manageable without any sort of assumptions about futuristic energy capabilities.

These sorts of ultra-compact systems around ultracool dwarfs are ideal for solar empire adventures. They're admittedly foreign, but it's certainly a trade-off worth thinking about.
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Zinegata
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PostPosted: Fri Feb 24, 2017 8:33 am    Post subject: Reply with quote Add User to Ignore List

FrankTrollman wrote:
BBC, on Eros 433 wrote:
In the 2,900 cubic kms of Eros, there is more aluminium, gold, silver, zinc and other base and precious metals than have ever been excavated in history or indeed, could ever be excavated from the upper layers of the Earth's crust.


Basically all we have to do is find one high metal content asteroid of medium size and it is a richer mining source of metals than all mines on the Earth's surface that have ever existed in history or could ever be built. If our society ever wants to go really crazy with metals - like building houses out of high tech ferrous foams and shit, then we need to get our hands on an order of magnitude more metal than we have right now. And that's completely available inside the solar system from just a few hyperdense rocks.

-Frank


Uh, there's a big difference between there being a lot of metal in an asteroid and there being a lot of extractable metal in an asteroid:

http://news.bbc.co.uk/2/hi/sci/tech/401227.stm

Quote:
If Eros is typical of stony meteorites, then it contains about 3% metal. With the known abundance's of metals in meteorites, even a very cautious estimate suggests 20,000 million tonnes of aluminium along with similar amounts of gold, platinum and other rarer metals.


What's important here isn't that there are possibly millions of tons of aluminum on Eros. What's important here is that it's still just 3% of the thing's overall mass. Aluminium, by contrast, is about 8% of the Earth's crust. That means you'll actually have to sift through more than twice the amount of useless rock to get the same amount of aluminum out of an Eros mine compared to an average Earth mine. For an asteroid mine to be profitable, it would have to show larger concentrations of rare metal ores (e.g. 25% aluminum composition); otherwise you're just spending more energy to create the same pile of rare metals.

And since the initial excitement over the Eros calculations (way back in the late 90s) the dawning realization is that most "rare metal" sites that we've already found actually have lower concentrations than traditional Earth sources. Granted, it's a big universe and someday we might find a wonderful 99% Titanium asteroid that would be totally profitable to mine, but until then it's put a damper on the whole "mine in space" thing.

(Note: This is conversely why Helium 3 mining has to be done in space. On Earth something like .001% of Helium is HE3, whereas higher percentages have been detected in Lunar Regolith. Quite simply, very little He3 makes it to Earth because of our atmosphere and magnetic field)

Secondly, when I say you need water for mining I don't mean you're going to use it for a wash plant like in Discovery Channel's Gold Rush. Rather, the vast majority of proposals for automated (and even human-operated) asteroid mining requires some kind of renewable on-site fuel source as Solar may not generate power reliably.

Water, which can be split into hydrogen and oxygen, tends to be a really convenient fuel source in addition to all of its other useful properties (like say keeping astronauts alive); and indeed it's probably the only one that you can hope to find in an asteroid that also contains the metals you want.


Last edited by Zinegata on Fri Feb 24, 2017 8:45 am; edited 2 times in total
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FrankTrollman
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PostPosted: Fri Feb 24, 2017 9:27 am    Post subject: Reply with quote Add User to Ignore List

Using energy to split Hydrogen out of water and then getting some of the energy back when you recombine it is not a fuel source. It's an energy storage system. When you use terms that badly, it's hard not to think that you are completely talking out of your ass. If you need energy, and you do, you're still going to have to get it from nuclear reactors (whether that nuclear reactor is "the Sun" or not is up to you).

The point of asteroid mining is that there is no "down." Whatever is in an Eros sized asteroid is automatically within 6 kilometers of one surface or another. And that in turn is half the distance of the deepest holes we dig on Earth. An asteroid does not need to be particularly mineral rich to be a better source of metal than everything we have access to on our planet combined. And we also know that the metal density of asteroids varies a lot, and we get to choose which asteroids we cut up.

And let's not beat around the bush, some of the M-class asteroids are just reasonably pure metal. 16-Psyche is 181 kilometers thick and apparently simply made out of nickel iron. The entire world production of iron ore is 3 billion tonnes a year, and 16-Psyche has ten million times that and it's purer than anything we can reach in or on our planet. If our society for some reason needed to increase the amount of steel we used by a million times, that would doable off the take from one asteroid.

-Frank
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Mechalich
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PostPosted: Sat Feb 25, 2017 1:43 am    Post subject: Reply with quote Add User to Ignore List

The economics of asteroid mining depend on a lot of factors, and the value of the metals (or whatever other compounds you might be extracting) and the cost of mining may not be even in the top ten as most important. When comparing with the Earth-equivalent industry you have to think about the whole process cycle, from start to finish. So from the cost of the prospector to find a viable deposit all the way to the cost of transporting the ingots (or whatever the semi-finished product ready for industrial use happens to be) to an industry capable of using them, whether on Earth or elsewhere.

For example, unless you have a space elevator or something like it, the cost of landing your minerals on Earth (or in fact in any substantial gravity well) may be prohibitive. The comparison for Earth-based mining is someone driving a truck from the smelter to the factory. Likewise if you can't construct the majority of your mining equipment in situ and have to haul it out, you're subject to immense rocket expenses as a result. Note that if your equipment includes 'humans' then you're subject to the immense expenditure of hauling them out to the site. Again, this is compared to someone driving a truck on Earth.

Asteroid mining may or may not still be viable, depending on conditions and of course on the demand for the product on Earth or even whether there's demand elsewhere. If civilization is centered on Mars, with its reduced distance to the asteroid belt and its considerably less restrictive gravity well things are actually easier. If you can transmit people around the solar system and plop them into robot bodies like in Eclipse Phase it's much, much easier. If you have self-assembling nanobot replicators that handle the whole process from start to finish after you point the prospector ship at an asteroid, then go nuts. However, at that point your technological advances have almost certainly modified society to the point that a traditional 'space opera' model no longer really holds.

That's the real trick - building a solar empire that is cool without including a society-transforming technology that is likely to overwhelm the solar empire aspect of your worldbuilding. Eclipse Phase, being overstuffed with pretty much every major type of speculative future tech to come out of the last 20 years of science fiction, certainly has this problem. There are various devices to deploy. For example, the engine technology that enables everything can be based on alien physics that humanity doesn't properly understand (like in Mass Effect). It's a careful balancing act.
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OgreBattle
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PostPosted: Tue Feb 28, 2017 11:50 am    Post subject: Reply with quote Add User to Ignore List

This blog post has an overview of space combat, a shortand succinct read:
http://josephshoer.com/blog/2009/12/thoughts-on-space-battles/

I'm going the Gundam route where "awesome fusion reactor" tech makes for a highly efficient energy source for powering space flight. That they also radiate jamming waves and force combat to be within visual range is also convenient for space dogfighting. Heat seeking missiles still works though, spacecraft can have a part that looks like 'eyes' for laser comms.

Something with the power to do "Earth to Jupiter if you plan their orbits just right takes 1 year", maybe with R&R and refueling stations along the way on Mars, the asteroid belt (Ceres and all that water).

How do you decelerate in space though without just using thrusters in the other direction? This website says stuff further from the sun just starts to slow down but doesn't explain why:
https://www.spaceanswers.com/space-exploration/how-can-spacecraft-slow-down-after-accelerating-through-space/

Also found there's a https://www.reddit.com/r/worldbuilding/ which has some old threads about space travel and terraforming
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FrankTrollman
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PostPosted: Tue Feb 28, 2017 11:54 am    Post subject: Reply with quote Add User to Ignore List

If you talk about maximum speeds you are implicitly implying that almost all acceleration is done with booster rockets at the beginning of the journey, with limited maneuvering thrusters to achieve orbit or docking later on. If you're talking about round trip space ships powered by technobabble, those concerns are gone. If the space ships have reusable sources of meaningful thrust, they are simply not constrained by that at all and don't have to care.

If you want the trip to Jupiter to be a round trip sort of affair and you want it to be something that takes a long time (like: more than a few weeks), then you are probably looking at some sort of very low but continuous acceleration model - like solar sails or ramjets. We're talking about constant acceleration of 12 ten-thousandths of a meter per second - or more likely a couple of really modest burns followed by many months of coasting. To get to Jupiter in a year, your average speed has to be 18.6 kilometers a second, which is achieved in just over half an hour of 1g acceleration, or more likely about a day of less than a twentieth of that powered by some sort of solar collection sails.

Edit: To put things in Nautical terms, an aircraft carrier weights a bit over 102,000 tonnes, and has engines that output 190 MW. That would get you to Jupiter-in-a-year speeds in a bit under 3 hours. Now obviously actual aircraft carriers run their engines night and day for weeks on end, so your technobabble is going to be about why they are getting acceleration that is much much worse than that. Good places to start would be having limited amounts of reaction mass if you are using some form of rocketry. Perhaps they load up on water to super heat and shoot out the back to get acceleration and they will just run out of stuff to throw after a few hours and they have to coast the rest of the way.

-Frank

-Frank


Last edited by FrankTrollman on Tue Feb 28, 2017 12:46 pm; edited 1 time in total
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rasmuswagner
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PostPosted: Tue Feb 28, 2017 1:25 pm    Post subject: Reply with quote Add User to Ignore List

Big-ass propellers (or jet engines, if you want to be less silly), and a gateway device that puts your ship 1% into a parallel dimension where those propellers can interact with something. Of course you can crank up the gateway field to increase acceleration, but then things start slipping through.
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Stahlseele
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PostPosted: Tue Feb 28, 2017 6:55 pm    Post subject: Reply with quote Add User to Ignore List

so basically the exact opposite of kavitation just in space?
interesting idea at least . .
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Hicks
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PostPosted: Thu Mar 02, 2017 4:30 am    Post subject: Reply with quote Add User to Ignore List

Children of a Dead Earth, because I heard someone say realistic space battles, and at the moment there is no more realistic space battle simulation available. Everything is customizable. No multiplayer though, but it's like if KSP got grim-dark, and also used n-body physics.
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Occluded Sun
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PostPosted: Thu Mar 02, 2017 11:40 pm    Post subject: Reply with quote Add User to Ignore List

rasmuswagner wrote:
Big-ass propellers (or jet engines, if you want to be less silly), and a gateway device that puts your ship 1% into a parallel dimension where those propellers can interact with something. Of course you can crank up the gateway field to increase acceleration, but then things start slipping through.


I'm reminded of Asimov's The Gods Themselves, which if you adopted the central conceit and made the aliens a little less sympathetic, could be utterly terrifying.

Short version: a scientist conducting an experiment realizes that he's isolated a sizeable amount of an isotope which is impossible, given the rules of physics. Humanity eventually realizes that an alien civilization in a different universe is making contact, and sending its physical law to us, in an attempt to establish an energy-generating system. We take to it like ducks to water... and use the new system to run our entire civilization. Then a few scientists realize the implications, too late.
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deaddmwalking
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PostPosted: Fri Mar 03, 2017 2:15 am    Post subject: Reply with quote Add User to Ignore List

I recall them finding a solution - making it another universe's problem.

Human ingenuity.
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Zinegata
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PostPosted: Tue Mar 07, 2017 7:43 am    Post subject: Reply with quote Add User to Ignore List

FrankTrollman wrote:
Using energy to split Hydrogen out of water and then getting some of the energy back when you recombine it is not a fuel source.


If you're going to be real strict about the terminology then what you're looking for is the term propellant, rather than fuel (two very different things but are used interchangeably by most sci-fi terminology).

Without propellant how exactly are you going to move dirt around for processing? Nuclear reactors generate heat (and that heat can be turned to electricity) but for tons of rock to be moved around you need propellant.

And before you go "Ion Drive!" or other similar tech - note that those need propellant too; for instance Ion Drives use various exotic gases (Xenon was used by the Deep Space 1 probe) as propellant and you will eventually run out. Mass drivers are a little better off because they can use just about anything as propellant, but that requires a lot of electromagnetic energy to be produced and you will need workers to periodically pick up and load rocks unto it (which all but certainly will require the use of propellant). The only propulsion method that doesn't really use propellant are solar sails - but that't not going to be terribly reliable and I'm not really sure how viable it would be for specific purposes.

And splitting water isn't terribly problematic. All you need is a bit of electricity - which you get via solar panels or a nuclear reactor.

Again, the key term is "industrial process". If you want to mine thousands of tons of metal, you need to be prepared to move thousands of tons of stuff. Even in Zero-G you still need to be able to generate a lot of force to move stuff.

Quote:
The point of asteroid mining is that there is no "down."


Yeah, but you still need to move the dirt on it and sift for the valuable components. To excavate the metal in Eros for instance would require moving and sifting through more rock than has ever been mined on Earth too. That's why I keep repeating the industrial process bit. You can't just have 3 guys digging through tens of thousands of tons of rock with some man-portable power tools. They'll basically never finish.

Quote:
And let's not beat around the bush, some of the M-class asteroids are just reasonably pure metal. 16-Psyche is 181 kilometers thick and apparently simply made out of nickel iron.


Like I said, big universe and there may be a pure Titanium asteroid somewhere.

The issue, as Mechalich noted, is that even a 100% pure Titanium asteroid still needs to be transported to where people actually can use the Titanium. A titanium asteroid in the belt is a curiosity, not a resource, until it's in the hands of people who can turn that metal into useful things.

Indeed, I would note that for reasonably "pure" asteroids it may be wiser to just attach an engine on it (with an efficient drive that uses low amounts of propellant) and to drop it down the Earth's surface so long as we are reasonably sure we can crash it into an uninhabited area and it won't trigger big environmental problems. Having a 10 ton Titanium asteroid crash into Siberia and have it "mined" on Earth would probably be cheaper than sending a crew into space to mine it bit by bit.

In particular, I would note that this is an option that's totally encouraged in Terraforming Mars. Rather than mine asteroids and send stuff down to Mars, players are encouraged to drop entire asteroids into the Martian surface to both increase available metals or water on the surface and to trigger increases in temperature. The most extreme case being attaching a bunch of engines on Deimos and dropping one of Mar's moons unto the planet itself. Big Grin

In short, the game turns you into a Gundam villain. Except your actions are totally legal and profitable. Big Grin


Last edited by Zinegata on Tue Mar 07, 2017 7:55 am; edited 4 times in total
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Stahlseele
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PostPosted: Tue Mar 07, 2017 9:26 am    Post subject: Reply with quote Add User to Ignore List

For the crashmining approach i'd propose to use the moon.
It is our shield against space rocks and close enough to get there and back in a reasonable time frame (read hours to days).
Meaning you can effectively view the moon as a rather big and expensive to run oil rig, just for minerals instead of oil.
Depending on how all out you want to go with the colony for workers, you could even have a complete industry up there, as opposed to only mining.
There's reasonable expectations for there to be water/ice on the moon.
And Helium≥ as in Iron Sky. So you would have the basics needed for running a colony. Energy and water. And as established, the water can be turned into fuel/propellant(i get those mixed up on a regular basis as well) using the energy from the Helium≥.
But more sophisticated robotics would be better to have. Because even if they are heavier and thus need more energy to get them up out of our gravity well, after that all they reasonable need to function is a bunch of solar panels and the odd shipment of replacement parts and lube.
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