Best Hull/Thickness For Longterm Manned Spaceflight

[Spacescifi]

Scifi Scenario: Thrust and propellant are not a concern...that's taken care of. So how heavy materials are is not a concern either.

What is the best hull materials/thickness for long duration space mission?

Or a space station located halfway between here and Proxima Centauri? In deep interstellar space?

The goal: NOT to EVER have to replace your hull because space radiation has made it unsafe. Basically, I want a hull that can survive space radiation safely for at least a century, ideally centuries without needing to be replaced.

My guesses: A meter thickness of hull at the very least. Probably composed of lead and hydrogen rich plastic composites.

Two meters thick would be preferred.

Still...I reckon that may not be good enough. Space radiation over time is kind of uber.

Another option is to just use radiation absorbent fluids that one replaces periodically, kind of like a spaceship oil change.

Yet for that you need FTL or warp to get fluids replaced before they no longer block radiation.

What do you think?

Edited December 13, 2020 by Spacescifi

[cubinator]

Do you suppose you could make something...alive? Regenerating, healing, while taking in energy and a little bit of food?

[Spacescifi]

52 minutes ago, cubinator said:

Do you suppose you could make something...alive? Regenerating, healing, while taking in energy and a little bit of food?

 

That would be ideal...would it not?

I suppose any hull like that would also be more flexible than the rigid scifi trope spaceships we know.

Food? That's the harder part. Unless it has no problem eating asteroid rubble piles and converting THAT into energy.

Really much energy is all around us. What's difficult is concentrating and harnessing it to do useful work.

 

The only thing I know of that space has a whole lot of is radiation. If one had an FTL field that could concentrate a whole light hour's worth of space radiation in a second and actually harness it for useful work...that would be something.

The problem is actually less concentration and more harnessing.

We made nuclear bombs so we know how to concentrate.

Yet we cannot harness massive energy levels without burning the containment box.

There is a way in theory one could do it...if they only knew how to bend light without physical structures surrounding the light.  Rather across distances at range,  perhaps via field projection?

Bending light is bending radiation, which means one could literally channel radiation away from his ship without it absorbing it.

It's the same tech that would enable invisibility cloaks, at the cost of not being able to see stuff  outside the field if inside the cloaking field.

Edited December 13, 2020 by Spacescifi

[GluttonyReaper]

23 minutes ago, Spacescifi said:

 

I suppose any hull like that would also be more flexible than the rigid scifi trope spaceships we know.

Food? That's the harder part. Unless it has no problem eating asteroid rubble piles and converting THAT into energy.

Not necessarily - I'm envisioning some kind of genetically engineered super-moss. Perhaps have a more traditional hull on the outsider, but then this organism forming a kind of "inner" wall, maybe even in a cavity between two walls. It wouldn't have to endure the full intensity of vacuum then, and it'll stick around as long your interior is at vaguely life-friendly temperatures and atmosphere. And it's a free CO2 scrubber, so that neat.

23 minutes ago, Spacescifi said:

 

I suppose any hull like that would also be more flexible than the rigid scifi trope spaceships we know.

Food? That's the harder part. Unless it has no problem eating asteroid rubble piles and converting THAT into energy.

Not necessarily - I'm envisioning some kind of genetically engineered super-moss. Perhaps have a more traditional hull on the outsider, but then this organism forming a kind of "inner" wall, maybe even in a cavity between two walls. It wouldn't have to endure the full intensity of vacuum then, and it'll stick around as long your interior is at vaguely life-friendly temperatures and atmosphere. And it's a free CO2 scrubber, so that neat.

[kerbiloid]

5 mm thick aluminium between the uninhabited modules.

[AHHans]

10 hours ago, Spacescifi said:

Scifi Scenario: Thrust and propellant are not a concern...that's taken care of. So how heavy materials are is not a concern either.

What is the best hull materials/thickness for long duration space mission?

Hmmm... Bring a planet.

Seriously: the atmospheric depth of 10 t/m² is very good at shielding us from cosmic radiation and impacts of solid objects. And being a gas that is bound to our "spacecraft" by gravitation means that it will "self heal" after every impact.

If you "just" want to shield against cosmic radiation as good as out atmosphere does, then that 10 t/m² is what you need. It doesn't really matter what material (and thus the physical thickness) that is made of. If you want better shielding then you need to add more mass, but if you think that the lack of radio-isotopes in your ship's hull - as compared to Earth - allows you to have more radiation exposure due to cosmic radiation then you can reduce the hull thickness.

As for the material? Anything that can withstand the impact of (micro?) meteorites and is cheap.

[Nuke]

use a double hull and put the fuel and other consumables in the space between the hulls. if you need to haul a lot of water around it makes a great neutron absorber. then just have a electromagnetic coil to handle the charged particles.

Edited December 13, 2020 by Nuke

[Spacescifi]

1 hour ago, Nuke said:

use a double hull and put the fuel and other consumables in the space between the hulls. if you need to haul a lot of water around it makes a great neutron absorber. then just have a electromagnetic coil to handle the charged particles.

That is one way I suppose....preferable for giant spacestations with fixed orbits and regular ressupply.

Exploratory starships going at warp or FTL at a LY per hour?

Probably need something else.

I know I said thrust don't matter, but I was being purposely vague. It more or less does not near gravity wells.

I plan to use a freeloader version of a gravity drive that converts gravity from a planet into direct thrust for the ship, which behaves weightless otherwise, even crew inside of it.

The inverse square law still applies, which means trying to use gravity thrust far away by some asteroid simply is a no go.

They would have to rely on rocketry, with all the known issues you know they have. Gravity drives would do the planning of trajectory and speed matching ahead for intercept, but actually flying on and off a space rock with negligible gravity would require rocket propellant.

My point? The more massive and dense a spacecraft is, the more of it needs to be proportionately propellant to move it anywhere quickly.

Unless one has fusion or AM burning off the propellant, which have known issues even if we had them.

[Nuke]

interstellar ships also have to contend with simple grains of dust, which will hit you like a nuke and would be very destructive without a big armor plate at the front of your ship.  though i think a low incidence plate would be better., essentially a long conical bit of armor that tries to deflect the debris rather than stop it completely. other than being destructive it would also rob you of momentum (assuming sublight relativistic flight). we also really dont know what is floating around in interstellar space, we have a rough idea of whats there, but the voyager probes have only scratched the surface.  i have no idea how you would deal with this problem with an ftl drive, i couldn't come up with anything better than what you see on star trek (the only main stream scifi i know of that gives this any thought at all). 

[Spacescifi]

5 hours ago, Nuke said:

interstellar ships also have to contend with simple grains of dust, which will hit you like a nuke and would be very destructive without a big armor plate at the front of your ship.  though i think a low incidence plate would be better., essentially a long conical bit of armor that tries to deflect the debris rather than stop it completely. other than being destructive it would also rob you of momentum (assuming sublight relativistic flight). we also really dont know what is floating around in interstellar space, we have a rough idea of whats there, but the voyager probes have only scratched the surface.  i have no idea how you would deal with this problem with an ftl drive, i couldn't come up with anything better than what you see on star trek (the only main stream scifi i know of that gives this any thought at all). 

 

Not if they don't travel through space they don't.

Hyperspace or it's many variants are an easy trope fix here.

Lest we want all ships to have massive spikes for noses.

In ST they deflect dust with some type of projected field deflection.

IRL that would be hard. But if possible it means that both STL and FTL up to a certain speed are no threat at all.

After all we are talking deflecting oncoming cosmic dust at 1 LY per hour.

If that can be done, no STL projectile can ever hope to even try to hit the ship without being overpowered and deflected by whatever OP deflector field the ship is using.

ST does not realize that it's tech is so OP it makes much of it obsolete even in the same setting.

Phasers and torpedoes would not hit anything at all, they would be deflected.

Edited December 13, 2020 by Spacescifi

[starcaptain]

Nate Simpson has said for KSP2 that they've already examined subliminal particle collisions and vessel degradation from interstellar travel as a gameplay mechanic. It proved to be counter-intuitive gameplay that lead to optimizing vessels that look like giant pills, made of enormously heavy shields at both ends of the vessel.. Some cleverer scifi authors have thought of shielding using water ice, and so their ships resemble icicles pointed prograde. However, gameplay that makes for convergence on these sorts of designs is boring, so KSP2 will not have any particle collisions in the interstellar medium, and vessel wear & tear will just be cosmetic on textures.

Whipple shields are a great lightweight solution for particle protection. I'd recommend looking up the ISV Venture Star for inspiration of what that looks like, for subluminal particle shielding.

As for radiation, unless you're going to presume some exotic material, radiation can only be proofed by biological resilience to it, or good ol' fashioned fat lumps of dense material. Smart people are trying to come up with some kind of lifeform that can eat radiation in a practical manner, but other than that, you might be looking at thick metal plating.

For an example of a genetically modified organism that eats radiation, look up the Japanese Miracle from the anime series Ghost in the Shell. Using something like that, suspended in solar-array-like algae panels might be a believable idea.

 

[Spacescifi]

15 minutes ago, starcaptain said:

Nate Simpson has said for KSP2 that they've already examined subliminal particle collisions and vessel degradation from interstellar travel as a gameplay mechanic. It proved to be counter-intuitive gameplay that lead to optimizing vessels that look like giant pills, made of enormously heavy shields at both ends of the vessel.. Some cleverer scifi authors have thought of shielding using water ice, and so their ships resemble icicles pointed prograde. However, gameplay that makes for convergence on these sorts of designs is boring, so KSP2 will not have any particle collisions in the interstellar medium, and vessel wear & tear will just be cosmetic on textures.

Whipple shields are a great lightweight solution for particle protection. I'd recommend looking up the ISV Venture Star for inspiration of what that looks like, for subluminal particle shielding.

As for radiation, unless you're going to presume some exotic material, radiation can only be proofed by biological resilience to it, or good ol' fashioned fat lumps of dense material. Smart people are trying to come up with some kind of lifeform that can eat radiation in a practical manner, but other than that, you might be looking at thick metal plating.

For an example of a genetically modified organism that eats radiation, look up the Japanese Miracle from the anime series Ghost in the Shell. Using something like that, suspended in solar-array-like algae panels might be a believable idea.

 

 

Thanks...yeah, too bad reality has to spoil...or rather our knowledge of our own limitations. We may overcpme them someday.

[kerbiloid]

Daedalus "had" a heavy beryllium _(iirc) shield on top.

***

FTL ship requires temporal shields because the FTL particles would damage it before they had collided.

***

If the massive spike on the nose is enough sharp, we can try to pierce the space-time with it to make a wormhole, so it would save time.

***

Most part of humanly absorbed radiation is not from space, it's from underground (unless you're a Mayan priest on a 6000 m high mountain).

27 g/cm² is considered enough to be relatively safe for a Martian expedition. The terrestrial 10 t/m² = 1000 g/cm² is a little overkill.
As humans can safely live at ~3..4 km above sea level (exp(-3.5/8) ~= 0.6), so ~500 g/cm² is enough.
Without the underground sources of radiation (radon, etc), probably ~250 g/cm² is normal for endless life.

Average density of an orbital station module is ~15 000 / (10 * 4) * 1 000 / 10 000 ~= 40 g/cm².

So, you can safely fly to Mars being surrounded by the lab, gym, shed, bath modules without another armor.
Having parallel fuel tanks allows you to die from zero-g sooner than from radiation.

As no flight longer than 2..3 years looks viable without artificial gravity (which requires a ~200 m wide ship), the radiation is a problem only for its outer layers.
Just keep inside and don't stare at stars too long.

[wumpus]

On 12/13/2020 at 6:55 AM, AHHans said:

Hmmm... Bring a planet.

Seriously: the atmospheric depth of 10 t/m² is very good at shielding us from cosmic radiation and impacts of solid objects. And being a gas that is bound to our "spacecraft" by gravitation means that it will "self heal" after every impact.

If you "just" want to shield against cosmic radiation as good as out atmosphere does, then that 10 t/m² is what you need. It doesn't really matter what material (and thus the physical thickness) that is made of. If you want better shielding then you need to add more mass, but if you think that the lack of radio-isotopes in your ship's hull - as compared to Earth - allows you to have more radiation exposure due to cosmic radiation then you can reduce the hull thickness.

As for the material? Anything that can withstand the impact of (micro?) meteorites and is cheap.

Using the empty husk of a mined asteroid is an old sci-fi idea.

The shuttle flew "backwards" orbiting.  The engines weren't needed to land, and had a lot of mass.  Using them as a shield for meteorites/orbital debris made sense (losing a windshield while flying "forward" would be a disaster).  Similarly, flying inside the solar system you want to present a lot of mass toward the Sun.  Ideally, bits without a lot of electronics or anything else that a solar flare might damage.  You'd also need cosmic ray shielding around all inhabited parts.  I'd assume that any "meteor shielding" would only be needed on the path of the eleptic.  But I've never heard of any spacecraft being lost to such things, so I imagine that avoiding such things would be trivial, and you wouldn't bother with shielding and just maintain an attitude perpendicular to the Sun.

[AHHans]

32 minutes ago, wumpus said:

The shuttle flew "backwards" orbiting. [...]

Didn't know that. But it makes sense, while the difference isn't as large as for travel on Earth you are still more likely to be hit from your prograde direction than your retrograde direction.

35 minutes ago, wumpus said:

Similarly, flying inside the solar system you want to present a lot of mass toward the Sun.

You don't need the 10 t/m² that I mentioned to shield against solar wind, I guess a lot less than 1 t/m² will be enough(*). That's still a few orders of magnitude more than you want to use on any spacecraft we are going to build in RL any time soon, but a lot less than you need to shield against the high-energy cosmic rays you get from outside the solar system.

P.S. (*) Oh, crud! For this kind of stuff the kind of material actually does make a difference. Heavier elements are better at shielding electrons and photons. So 1 t/m² of air (or carbon, or water) might actually be on the low side for shielding, while 1 t/m² of steel should be plenty.

[kerbiloid]

12 hours ago, wumpus said:

Using the empty husk of a mined asteroid is an old sci-fi idea.

Until the reader realizes that the asteroid is usually a heap of stones, rather than a monolith.

11 hours ago, AHHans said:

while 1 t/m² of steel should be plenty.

Absolutely. Because such heavy ship will stay on the Earth.

[radonek]

@kerbiloid 16/Psyche :-p

To the topic, I like the idea of self-healing lichen, but I'd grew it on outside, to prevent dust abrasion and act as a kinda whipple shield. For radiation, habitable part could cower under water shield. Most other parts don't matter since they will be zapped by drive anyway.

[kerbiloid]

22 minutes ago, radonek said:

16/Psyche :-p

Quote

Psyche appears to be an exposed metallic core or a fragment of a metallic core^[21] from a larger differentiated parent body some 500 kilometers in diameter. If Psyche is indeed one, there could be other asteroids on similar orbits. However, Psyche is not part of any identified asteroid family.^[28] One hypothesis is that the collision that formed Psyche occurred very early in the Solar System's history, and all the other remnants have since been ground into fragments by subsequent collisions or had their orbits perturbed beyond recognition. However, this scenario is considered to have a probability of just 1%. An alternative is that Psyche was broken by impacts, but not catastrophically torn apart. In this case, it may be a candidate for the parent body of the mesosiderites, a class of stony–iron meteorites.^[28]

https://en.wikipedia.org/wiki/16_Psyche

Even if it's metallic, this doesn't mean it's a slab. It's still a heap of scrap and stones.

Edited December 16, 2020 by kerbiloid

[wumpus]

22 hours ago, AHHans said:

Didn't know that. But it makes sense, while the difference isn't as large as for travel on Earth you are still more likely to be hit from your prograde direction than your retrograde direction.

You don't need the 10 t/m² that I mentioned to shield against solar wind, I guess a lot less than 1 t/m² will be enough(*). That's still a few orders of magnitude more than you want to use on any spacecraft we are going to build in RL any time soon, but a lot less than you need to shield against the high-energy cosmic rays you get from outside the solar system.

P.S. (*) Oh, crud! For this kind of stuff the kind of material actually does make a difference. Heavier elements are better at shielding electrons and photons. So 1 t/m² of air (or carbon, or water) might actually be on the low side for shielding, while 1 t/m² of steel should be plenty.

Not for solar wind, but for bursts such as solar flares and whatnot.  You probably don't need to maintain that attitude constantly (I think the real danger is ions emitted in a solar flare, or other such things with real warnings), but I'd keep it that way "just in case" the Sun decided to emit a large EM event in my direction without warning (since you have to be able to turn that way occasionally anyway).  From memory, there was a real fear that the Apollo astronauts would be in real danger from such an event (although granted, a LEM is one of the flimsiest vehicles ever produced by humans).

 

3 hours ago, kerbiloid said:

https://en.wikipedia.org/wiki/16_Psyche

Even if it's metallic, this doesn't mean it's a slab. It's still a heap of scrap and stones.

If there's a solid core (or at least a large chunk somewhere in the pile) that would be enough.  Granted, that assumes you are capable of mining through the thing, and that you are digging out ore instead of breaking metal into useful sizes.  Real asteroid mining may involve just sifting through the rubble looking for nearly entirely metal bits and melting them with minimal smelting.

[kerbiloid]

3 minutes ago, wumpus said:

If there's a solid core (or at least a large chunk somewhere in the pile) that would be enough.  Granted, that assumes you are capable of mining through the thing, and that you are digging out ore instead of breaking metal into useful sizes. 

It's 200 km in diameter, and probably has many kilometers thick upper layer made of scrap and stones.

It's a long way to go dig.

P.S.
Why nobody is still flying to Psyche, when we need to know so much.

Edited December 16, 2020 by kerbiloid

[AHHans]

6 minutes ago, wumpus said:

Not for solar wind, but for bursts such as solar flares and whatnot.

Not really. You need the large thickness of shielding to shield against (extra-solar) cosmic rays, because the single particles have high energies (>> several GeV, up to 10²⁰ eV). These particles form particle cascades when they hit the atmosphere or denser matter. To shield against this you need enough material to have a high enough number of generations in the cascade so that the single particle energy is low enough to be stopped. (The cascades from the higher energy cosmic rays don't get stopped in our atmosphere, but they are few of those so that's what we can live with.)

Solar wind, solar flares, coronal mass ejections, etc. is all low energy stuff(*) with energies of usually less than 1 GeV per particle. Compared to the high energy comic rays there are lots of them - and even more during solar flares - so that's what causes the largest biological effect for the time being. (There are a few orders of magnitude between the number of solar and extra-solar particles.) But you don't actually need all that thick shielding to nearly completely block that. You "only" need about 10 cm of steel as shielding, not a meter or more.  But even that is beyond our capability right now - and for the foreseeable future - so people are worrying  about that before they start thinking about the smaller and even more impossible to shield against threat.

(*) At least for someone who worked on detecting cosmic rays at energies of 10¹⁷ eV and higher.