Hey there! My name is Cozy, and I’m writing a science-fiction book. The problem is, I want it to be a lot more heavy on the science than most similar books, but I’m not particularly knowledgeable. So I’m looking for either answers to questions I have from people smarter than me, or someone who is willing to teach me how to find/discover/learn the answers on my own. Anyway, my current question is, what would be the most realistic way to mine ice from the surface of Pluto? Or am I mistaken in believing that Pluto is mostly ice? Any answers would be appreciated, I look forward to learning!! Thanks for reading!
Does it have to be Pluto specifically? There are plenty of other objects in the Solar System with plenty of ice, and many of them are much easier to mine than Pluto would be. And why is it being mined? Is it to be sent to some planet, or used in space? Where? And if it’s a planet, does it need to be brought down gently, or are high-speed impacts OK (or even preferred)? Do you just want a quantity of water, without caring about its form, or do you need it solid? And if solid, does the shape or size of the chunks matter to you?
I’m not particularly knowledgeable on space topics, but I can at least tell that the question is pretty vague. Does the ice need to be returned to earth, or is it to be used for a 1-way journey somewhere else?
Just in case no one else answers, I’m pretty sure the answer will be something like this: Launch a manned or unmanned probe to Pluto at an opportune time, have the probe land via some convenient method, have people or a robot fill up a compartment on the probe with ice, then have that detach from the rest of lander and fly off to wherever is needed, possibly meeting up with an orbiter (like on the Apollo missions).
For what it’s worth, most “scientifically plausible” science fiction books are written by authors with backgrounds in physics or other hard sciences. I imagine it’d be very difficult, if not impossible, to write hard science fiction without a strong grasp of the science behind it. It’d be akin to writing a math textbook without understanding the math.
Based on observations by the Hubble telescope, Pluto’s density is such that it is currently thought to be about 50 to 70 percent rock, with the remainder made up of water ice and frozen nitrogen. Scientists currently think that most of the rock has made it to Pluto’s core, leaving the ice outside of that and the frozen nitrogen on top.
The Kuiper belt is a region beyond Neptune that contains a whole bunch of little rocky iceballs, and Pluto happens to be one of these little iceballs. While Pluto is larger than other known Kuiper belt objects, it isn’t unique in structure.
There are other sources of water ice that would be easier to get to. Several of Jupiter and Saturn’s moons have water ice on the surface, so you wouldn’t need to drill through frozen nitrogen to get to it. Also, if you are trying to get this water back to earth for some reason, the asteroid Ceres is currently thought to contain a lot of water ice, and it’s a heck of a lot closer than Pluto.
There’s a LOT I didn’t know about so didn’t consider. To Chronos, no, it does not have to be Pluto, but we do need a very large amount of ice. It’s being mined to use as ablative shielding for 4 generation ships leaving our solar system. The ships are being constructed in orbit because they’re too large to leave the atmosphere effectively. In this world, the idea of “shields” or “force fields” never came about, so they need something to protect them from micro-meteors and the like. I was told that the easiest way to do that would be to use ice as ablative shielding, and the person who told me said that Pluto would be a good place to start because there’s so much ice there. It does have to be solid, but it doesn’t have to be able to be brought down to a planet. So far as the size of the chunks and the shape, I honestly am not sure, I don’t know enough about engineering to determine what I would need for my ships.
To respond to Joker, I’m sorry for the vagueness. DX Again, I’m not really that knowledgeable, so I’m not 100% certain what exactly I need, I’m going off of what others have told me. No, it doesn’t need to go back to Earth, it’s for a one-way journey. And I need a LOT of ice, so small probes wouldn’t be enough. Also, I may eventually give up and just wing it, but I really do want to try and make it as realistic as possible, if I can. 
And to engineer, no, it doesn’t need to go back to Earth, it just needs to be solid. And do you think that the other sources would provide enough ice to make the shielding, or would I just need to look for another source entirely?
I’m not sure how a society could develop spaceships without the idea of shielding or barriers. I mean, even cavemen evidently know that you put something (a cave) between yourself and bad things (like rain). If a society was so primitive that they couldn’t understand that, they couldn’t possibly build a spacecraft, which requires exceedingly advanced shielding, to protect from radiation, heat loss, micrometeorites, and what not. Plunking down a giant disk of tungsten in front of your spaceship is probably the easiest part of building it.
I really don’t want to say “your premise is flawed”, but I’m not sure the best science could make ice shielding a plausible idea.
When I say shielding, I mean the kind you see in Star Trek. They understand fully that they need to protect themselves against the dangers of space, they simply can’t do it with force fields. They have to use physical, non-technological shielding.
You would mine Pluto by going to the center of the planet and working from the center outward. The reason you do this is the planet itself would shield you from harmful radiation. Also you would use the by product of your ice mining, which is metal ore, to construct your new home at the center of Pluto. Building rooms and terrariums that you heat using hydrogen powered engines. Hydrogen comes from splitting water atoms. Water being made of H2O from your ice. As you mine out more and more of Pluto’s center you have a growing city growing bigger and bigger. There can’t be gravity equivalent to Earth on Pluto and I don’t know solution to that.
Okay… is there a reason they’re using ice? I think that rock or metal would probably do at least as well, especially as they have higher melting points.
Perhaps a better reason to chose Pluto, storyline wise, is not to get the ice there (as there are other places), but to transition the first generation to lifetime space travel. It gives them a goal to achieve (first people to walk on Pluto) and a chance to set foot on a planet (or so) for the last time.
This would most likely mean a slower route out of the solar system, taking several more years then a more direct route, but for the people on the ship it might be what is needed till the generation of space children take over and used to interstellar travel w/o FTL drives.
The route would be gradual and take quite a bit of time to match speeds. However once at Pluto, it would be really easy to take off and fall almost into the sun (just orbit around it - the close the better), and thrusting at the nearest point to the sun, would give a great velocity boost to leave the solar system.
Yeah, that’s true. They do have around 400-450 years of travelling to do, and that’s with an entirely made-up solar system for the destination. But this isn’t something that will happen quickly. It will take years, possibly decades, to simply BUILD the ships, much less get them moving.
Better shielding / mass ratio?
What about hijacking an existing comet, preferrably one in a highly eccentric orbit, and merely attaching your habitation / propulsion modules to it? This could be done at the range of Pluto; the comet / spaceship would then pick up a lot of speed approaching the sun. At perihelion, burn your thrusters full speed - and exit the solar system!
From what I was told by someone on the Universe Sandbox forums, Ice would be the best because it’s easy to transport and light, and metal would be heavier, requiring more fuel.
That could be done, if it would be workable… Actually… Would it be possible to build the ship inside of the comet as it went through our solar system…? Or is that a dumb idea? Also, would they still be able to steer it?
As I understand it, hydrogen-containing compounds (like water ice) are make particularly good shielding against proton and neutron radiation. Or rather, hydrogen makes particularly good such shielding, and hydrogen-containing compounds are a more convenient way to hold a bunch of hydrogen at sufficient density.
Well, workable is relative to technology - at least in fiction, I think a lot can be done with cables of carbon nanofibers, fusion power and whatnot…
Regarding the time frame, I don’t really know…I’ll see if I can find any numbers or do a crude estimation…
You would certainly have to dig into the comet, if only to make a firm anchor for your proposed modules… the first step to steering it would be to get rid of the rotation, and this might not be so easy - but let’s say that this particular comet has an extraordinarily low speed of revolution!
You would probably want to keep the bulk of the comet in front of you, so no need to dig into the center.
I won’t take the fun away from you as a writer, but may I suggest that, in time, it may even turn out that there’s a perfectly logical reason for that low angular velocity…?
OK, I looked up Pluto on Wikipedia, and it seems as its’ average orbital speed is 4.7 km/s, although this varies considerably, as Pluto has a decidedly non-circular orbit.
This is a very crude estimate, but using that number, and dumbing down to circular motion, you would expect any object in solar orbit, however eccentric, to have a velocity not more than 6.7 km/s when crossing Pluto’s orbit.
Can your rockets match that, with the intended payload?
They will sure as shit need to charge more than $1.29 per bag.
It would probably go to the boutique vodka makers.
Some 6 - 7 km/s ain’t all that bad though - and remember, it wouldn’t have to be achieved in a day! More likely, the to-be-starship (or it’s components) would have had years to build up that speed, gradually spiraling outwards from their home planet.
They may even have gained speed by making a turn around Neptune…