Do you want to build a spaceship?

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maurvir Meat popsicle
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Since I'm apparently being a smartypants today, I figured I would toss out this thought experiment. Do you want to build a space ship that can safely explore the outer solar system? (and, conceivably, become the basis of a generation ship, but that's a bit out there still)

I believe that we aren't that far from being capable of building a vehicle capable of keeping humans safe and healthy for the extended period of time required to personally visit the outer planets. So, let's review what we need:

1) Air
2) Water
3) Food
4) Shelter (and heat)
5) Gravity
6) Power
7) Propulsion
8) Navigation

Air is fairly obvious, but we have a problem. Humans consume oxygen and generate carbon dioxide. Simple enough, scrub the CO2 from the air. Except now all your oxygen is trapped in the form of CO2 and you eventually run out. Not cool. How do we solve that? Well, we either strap a metric crap ton of O2 bottles to the ship, or we recover it. There are two ways to do this - electrolysis or hydroponics. Both have their upsides and downsides, but hydroponics helps resolve problem #3 as well. Maybe a mix of both, in case the plants don't do well.

Water is also fairly obvious, but it comes with a second potential benefit to #4. Radiation in space is a much different animal than radiation on Earth. Without a magnetosphere and heavy atmosphere, you will be constantly bombarded by charged particles and free neutrons. With a sufficient amount of water all around you, this problem becomes much more manageable. Oh, and now you have all the water you need to perform hydroponics!

Food is also fairly obvious, but here is where we may find our first truly new synergistic effect. The one part of Biosphere II which is still up and running is the artificial reef. Turns out the giant aquarium worked pretty well. Given that we need 40' of water on all sides, which is pretty deep, it may be possible to turn our watery shield into a hydroponic "sea farm". By securing large kelp to the walls and stirring the water with pumps, we could grow a fairly large amount of food in a short period of time. Additionally, fish stocks could be maintained within the shell providing a true protein.

Shelter. In space this means a lot more than it does on a planet. It has to keep our air and water in while keeping rocks and radiation out. Now, given a depth of 40' on all sides for our watery hydroponic shield, we are going to have a major mass problem, particularly given that the outer diameter of the vehicle will need to be approximately 1.4km in order to generate a reasonable inertial force approximating gravity. Fortunately, we don't necessarily need complete rings, but I'll leave that for the next section. Instead what you need is a way to deal with micrometeorites (or worse). A paint chip was able to crack several layers of the glass on a space shuttle once. A paint chip. Obviously there are worse things out there to deal with, but we have a crap ton of water shielding us, plus all that kelp. It's like a natural ballistics gel. However, you don't want it all leaking into space, particularly sine we are going to be simulating gravity in the next section.

This is where materials science comes in. Our outer shell will need to be more or less "self healing", and it will need to spread the force of an impact over a larger surface area like a bullet proof vest. A combination of a thin self-healing polymer layer combined with another thin layer of non-Newtonian fluid could manage that without too much fuss. You would need a lot of it, as the entire outer surface will have to be covered, but it's doable. Particularly if we carve up our ship into multiple sections instead of a continuous ring. we still have the minor issue of water applying pressure to the outer walls, which means we will need a fairly strong material to handle it. Fortunately, this is largely a solved problem. Aquariums deal with it all the time. It will need to be radiation resistant, though, as radiation often makes materials brittle over time.

We also have a solution for sanitation, and it goes back to Biosphere II. We can reintroduce the waste products from the crew - CO2, urine, and stools - as inputs to the hydroponic shelter itself. There may be some need for processing the poop and urine to avoid poisoning the fish, but many of the products will be directly either directly or indirectly usable by the kelp. The amount that actually has to be drawn from the system and stored or processed will likely be fairly small in comparison, and even that could be burned off or dumped overboard. This does mean reverse osmosis will be required to directly use the water (since we will be creating an aquarium in our outer shelter), but that's a solved problem. We just need to make sure we carry enough membranes.

Heat is also an issue, but instead of trying to warm things up, we will have the bigger problem of keeping everything cool. That is, I suspect our ship will be covered in radiators to dump heat, rather than the other way around due to the the sheer amount of water itself, which will need to be kept at a temperature adequate to maintain our kelp and fish. (So around 76-80 degF) However, at some point we will lose heat due to radiation, which can be topped off from the coolant reservoirs that keep our nuclear reactors from overheating.

Gravity. We don't really think about it, but we actually do need it. Without gravity, our bodies start to fall apart, and given enough time, people would be stuck in space unable to function in a gravity well. This is well worn territory - you need a large, spinning vehicle with a radius of about 200m. Fortunately, most of that can be empty with only support structures holding things in place. However, it does start to set up some constraints on our outer "ring". Instead of a continuous ring, we instead use a series of spheres evenly placed to maintain the center of gravity about the central service vehicle (where the engines are) connected by structural rings that allow passage via vehicle of some sort.

Power is an obvious problem as well. Right now, we are probably talking about a set of fission reactors, but that sets a limit to our mission. We can supply enough to last for a decade or more, but nuclear materials are necessarily dense, heavy materials. A better choice would be fusion, but we aren't quite there yet. We do, at least, have the benefit of microgravity, which means containment of the plasma should be simpler. Unfortunately, this places another constraint on the rotational speed (due to Coriolis effects), which may impact our minimum ring diameter.

Propulsion. Our space ship is now exceptionally heavy from water alone, and that doesn't even get into the tremendous amount of metal, plastic, etc. Chemical rockets aren't going to cut it unless we plan to take the extremely slow tour of space. No, we need nuclear propulsion ala the original project Orion. Our disk will need to be at least the same diameter as the outer ring with shock absorbers at each spherical segment. That's a pretty big ablative disk, and quite possibly what nixes the whole thing. However, if you can create the ablative disk, you can now drop small nukes through the back and get up to speed pretty fast.

At the sheer size we are talking, acceleration will be pokey, but that's fine. Too much acceleration orthogonal to the ring will cause stress on the vehicle and could potentially cause a failure of a possible fusion reactor.

Navigation. Our space ship is going to be spinning in order to recreate gravity, which means we will be ballistically stabilized (like a rifle round). This is good if we are going in a straight line. Not so good if we need to turn. This means planning the trip far, far in advance and taking advantage of gravity wells to steer us. Otherwise, we aren't going to be doing much more than minor course corrections, and even then it will take some hefty rockets. Reaction control thrusters aren't going to cut it with a ship like this. Instead, steering may involve something closer to an F5 rocket. Doable, but it means keeping a large amount of propellant on board - presumably in the middle of the vehicle where the lack of gravity isn't an issue.

So, what do we have? We have a ring comprised of multiple artificial "seas" where the crew live in "submarines" which are all connected together by a metal superstructure. The crew obtain their air, water, food, and shelter from the vehicle itself. Further, their liquid and solid waste are used to fertilize the plants and feed the animals in the ring. We have created a self-contained habitat that should be able to sustain all of the life forms on board. Finally, we have also created a propulsion system capable of moving the many thousands of tons of stuff at a realistic velocity.

Thoughts?
arkayn Aaarrrggghhhh
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We better come up with the tech from Star Trek quickly.
Donkey Butter jerk face
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You may have solved some of the issues but this is at least 100 years out because where do we build it?

I mean this could never be build on earth and then rocketed into space. So this has to be built in space right.

So how do we do that? I'd guess by using a "space elevator" since the rocket powered transport of today just isn't feasible. (unless you have an alternate plan for construction)
maurvir Meat popsicle
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Yeah, that all assumes you are building in space, which means creating an infrastructure in space first. Also, that's a crap load of metal, water, etc., that has to come from somewhere - probably the moon. My guess is that this thing would be built in lunar orbit.

However, aside from the scale of it, most of the actual technologies exist now. Self-healing polymers exist, non-Newtonian fluids exist, mobile fission reactors are actually becoming obsolete, etc. Aquaculture is also pretty well a mastered technology, though getting it to work in microgravity may be a challenge. Even the Orion nuclear engine concept was at the engineering stage when it was killed due to the nuclear test ban treaty.

The biggest issue is the scale of it.

Last edited by maurvir on Thu Apr 11, 2019 7:57 pm.

TOS
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the tech isn't there, nowhere near ... not just in terms of the vehicle itself but also the lifting capacity to get it built and launched

there's also no money or interest in such a mission, but i guess we can make those side-issues
maurvir Meat popsicle
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TOS posted:
the tech isn't there, nowhere near ... not just in terms of the vehicle itself but also the lifting capacity to get it built and launched

there's also no money or interest in such a mission, but i guess we can make those side-issues


Well, yeah, which is why I asked the question. It would cost in the many tens of billions, and require support infrastructure both in space in and on the moon. However, I disagree about the tech. We don't have all of it, but we have quite a bit of it.

Keep in mind, this thing would practically beg for modularity and most of the ship would be hollow voids with nothing but superstructure holding it together.

Last edited by maurvir on Thu Apr 11, 2019 8:01 pm.

juice Inadvertently correct
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Maybe if the commies were going to get there before us...
ukimalefu Rebel? resistance? why not both?
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TOS posted:
the tech isn't there, nowhere near ... not just in terms of the vehicle itself but also the lifting capacity to get it built and launched

there's also no money or interest in such a mission, but i guess we can make those side-issues


I believe the technology is available, but it would take LOTS of money and a LONG time.

Think about the International Space Station. You build an interplanetary spaceship like that, build parts on Earth, assemble in low end orbit, then send it out. So lots of time, and money, and... people willing to risk spending a few years in space.

Impractical, difficult, unlikely, but not impossible IMHO.

I still believe humans will set foot on Mars this century. Hopefully I'll get to see it. Beyond that, last quarter of this century, maybe next century. It's happening.

Oh, and don't even attemp to land on Europa.
maurvir Meat popsicle
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ukimalefu posted:
Oh, and don't even attemp to land on Europa.


Screw that. Europa is probably the best place after Mars for a new colony. It is a water-covered moon with an ice coating and oxygen atmosphere (if thin). Yeah it's going to suck when you have radio blackouts with Earth, but now you are dealing with relatively tried and true submersible technology that we perfected decades ago - just on a remote moon.
ukimalefu Rebel? resistance? why not both?
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maurvir posted:
ukimalefu posted:
Oh, and don't even attemp to land on Europa.


Screw that. Europa is probably the best place after Mars for a new colony. It is a water-covered moon with an ice coating and oxygen atmosphere (if thin). Yeah it's going to suck when you have radio blackouts with Earth, but now you are dealing with relatively tried and true submersible technology that we perfected decades ago - just on a remote moon.


But... but... the black monolith is not going to be happy, but ok.
I agree this tech is nearly there. I'd say we'll be much more seriously thinking about habitats in space for more than a handful of people in about fifty years.
tbh I'd want to focus on a near-earth orbital at first to test the technology before going where there's no help when human waste hits the fan.
DukeofNuke FREE RADICAL
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In a way, that's what we've been doing for the last sixty years.
Long term studies on humans in orbit is about done. Unfortunately there's long term problems. We'll have to work those out before we move permanently into space. Hence my 50 year estimate.
ukimalefu Rebel? resistance? why not both?
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The science of people being long term in space

some of it anyway

https://www.theverge.com/2019/4/11/1830 ... nes-health

Quote:
After years of processing data, the official release of a study comparing twin astronauts Scott and Mark Kelly is finally here. One clear trend emerged in the findings, which were published today in the journal Science: a year in space changed Scott Kelly’s body, but many of those changes were only temporary and vanished after time back on the ground.

A episode of Carl Sagan's Cosmos did a segment on ships proposed for space-faring.
C. Ives Lacks Critical stick fiddling Thinking
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This is already happening. Honestly, do none of you watch the news?

https://www.youtube.com/watch?v=_AUXpnB ... gs=pl%2Cwn
ukimalefu Rebel? resistance? why not both?
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C. Ives posted:
This is already happening. Honestly, do none of you watch the news?

https://www.youtube.com/watch?v=_AUXpnB ... gs=pl%2Cwn


:up:
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Do you want to build a spaceship?