mikegarrison

Colonization Discussion Thread (split from SpaceX)

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2 hours ago, kerbiloid said:

Wanna lunar base?

Ask them, how.

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32DBAE8800000578-3524147-image-m-10_1459

 

this is a horrible analogy,  the air is free and supplies can easily be brought in,  they have a 24hr day and an atmosphere meaning heating/cooling is a lot cheaper, and the ground is nothing like lunar regolith

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3 hours ago, Kerbal7 said:

I can't see any realistic Colonization taking place out into the solar system unless the deep space radiation problem gets solved. From what I've read this is a show stopping hurdle that has yet to find a solution. Even a flag and footprint mission to Mars runs into this deadly problem.

It's manageable for an expedition. NASA DRMs have it slightly exceeding lifetime allowed workplace radiation exposure as set by OSHA, so any Mars astronauts for NASA would not fly again. Mitigation schemes are also possible (the DRMs have little/no shielding). The Lockheed Martin Mars Basecamp idea has the crew sleeping quarters surrounded by the propellant tanks, so that substantially reduces radiation exposure in flight to and from Mars.

For both the Moon, and Mars, regolith could be used as shielding. Have robot excavators bury the hab areas ahead of crew arrival, for example. They might bury just the sleep quarters to start (a smaller, hardshell lander), then the crew inflates a larger, connected common area hab, and works on shielding it themselves (for the year stay variety of mission).

 

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12 minutes ago, insert_name said:

this is a horrible analogy,  the air is free and supplies can easily be brought in,  they have a 24hr day and an atmosphere meaning heating/cooling is a lot cheaper, and the ground is nothing like lunar regolith

I find the analogy amazing.

Underground vaults covered with a meter of ground protecting from radiation, micrometeorites and temperature variations.
Numerous small but comfortable patio just asking for being covered with thick glass domes keeping the air inside, allowing to take UV baths every day.
Roads right between the roofs allowing to walk along a concrete street rather than regolith.

Of course it requires supplies and air like any colony out of the Earth, did somebody promise that that will be easy?

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7 minutes ago, kerbiloid said:

I find the analogy amazing.

Underground vaults covered with a meter of ground protecting from radiation, micrometeorites and temperature variations.
Numerous small but comfortable patio just asking for being covered with thick glass domes keeping the air inside, allowing to take UV baths every day.
Roads right between the roofs allowing to walk along a concrete street rather than regolith.

Of course it requires supplies and air like any colony out of the Earth, did somebody promise that that will be easy?

but these arent buried for radiation or micrometeorite protection, and square cube law makes it more efficent to have one large park than several small patios, this is important as space-rated glass isnt cheap, and pressurized tunnels are better than roads for lunar colonies as spacewalks take a long time to prepare for, are difficult, and waste atmosphere.

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Tunneling might be tricky, but you could build a town that looks like a chinese one, where it's all completely buried (so that vehicles could operate on the surface, or solar panels, etc), except for limited common areas that have some windows for seeing out.

You could build habs in an arc along one side of a crater, then push regolith from above down on top. The habs could have windows facing in towards the center of the crater, with a LARGE overhang. If the crater is deep enough, and the overhang long enough, the inside would be highly protected from GCRs, and even if the GCR flux was high right next to the window, you take a step back, and you're fine.

I made a crappy drawing a long time ago, let me find it...

ViJPe4V.jpg

 

That is looking at the crater wall, rather than across. Basically, if you have no LOS to the sky, you are pretty safe. If you get a sliver of sky, then depending on how the areas are inside, you are also pretty safe. Put your sleeping areas away from the windows.

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29 minutes ago, insert_name said:

but these arent buried for radiation or micrometeorite protection

Any house under a meter thick layer of ground is protected against radiation and micrometeorites, intentionally or not.
They built this intuitively.

29 minutes ago, insert_name said:

square cube law makes it more efficent to have one large park than several small patios

1. Square cube law makes it more efficient to have several small domes rather than a large one because the lever is shorter and mass per contact area (so pressure) is lesser.

2. It's much easier and cheaper to repair or replace a small glass rather that a large one.
That's exactly why vintage houses have such windows. It's just cheaper to buy a new glass if broken.

Spoiler

ad39f5ed78.jpg

3. If a small dome is broken, bodycount is lesser. Rather than a whole city gets depressurized.

4. It's cheaper to make and deliver a lot of small similar domes than build an unique one. Economics basics.

29 minutes ago, insert_name said:

this is important as space-rated glass isnt cheap,

Total volume and mass will be more or less the same because a large dome must be thicker proportionally to its diameter.

29 minutes ago, insert_name said:

pressurized tunnels are better than roads

Houses are instead of tunnels. Roads are above the roofs between the domes.

29 minutes ago, insert_name said:

and waste atmosphere.

Which is much easier to control when the full volume is splitted into local areas.

P.S.
If you ever have been to a military camp you'll find this town view familiar.

P.P.S.

27 minutes ago, tater said:

Put your sleeping areas away from the windows.

Make cupola like on ships instead of windows, and screen displays with waterfall screensavers.
When houses are placed close to each other like in this town, their walls are neighbors' protection.

Edited by kerbiloid

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Earth radiation levels are about like 1,000g/cm2 of radiation shielding in space. 2-3 meters deep of lunar regolith is about 400 g/cm2. This is adequate for some level of protection, but inadequate for flares.

Numbers I see for loose regolith are on the order of several meters deep.

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Spoiler
38 minutes ago, tater said:

Earth radiation levels are about like 1,000g/cm2 of radiation shielding in space. 2-3 meters deep of lunar regolith is about 400 g/cm2. This is adequate for some level of protection, but inadequate for flares.

Tell this to PB666 before he builds an O'Neil cylinder made of thin carbon. I wat considered too paranoidal suggesting a ha;f-meter of iron. :cool:

According to the ESA Martian ship study published on the forum, (2.6.4.2-2.6.5)
9 g/cm2 on a spaceship decreases overall dose down to 2 Sv/year.
25 g/cm2 on a spaceship decreases overall dose down to 0.12 Sv/year.
This includes GCR as well as solar flashes.

So, 50 g/cm2 (i.e. 20 cm of ground or concrete) would definitely protect you from the space radiation on the Moon.
1-2 m is a typical protection in "duck and cover" literature. It allows to survive on the nuke fallout trace and 2-3 days later quickly go away to a clean place.

For comparison: half-protection layer (or how is it in English) is ~ ( 23 / density, g/cm3), cm.

Edited by kerbiloid

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8 hours ago, kerbiloid said:
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Tell this to PB666 before he builds an O'Neil cylinder made of thin carbon. I wat considered too paranoidal suggesting a ha;f-meter of iron. :cool:

According to the ESA Martian ship study published on the forum, (2.6.4.2-2.6.5)
9 g/cm2 on a spaceship decreases overall dose down to 2 Sv/year.
25 g/cm2 on a spaceship decreases overall dose down to 0.12 Sv/year.
This includes GCR as well as solar flashes.

So, 50 g/cm2 (i.e. 20 cm of ground or concrete) would definitely protect you from the space radiation on the Moon.
1-2 m is a typical protection in "duck and cover" literature. It allows to survive on the nuke fallout trace and 2-3 days later quickly go away to a clean place.

For comparison: half-protection layer (or how is it in English) is ~ ( 23 / density, g/cm3), cm.

I bolded your figure. That's 120 mSv/year. A normal dose here on Earth is 3 mSv/yr. That's 40X too high.

We're in a colonization thread, not a mission to Mars/Moon thread. We know humans do OK at some dose rate that is maybe high altitude Earth. But regardless, it's on the order of 3 mSv/yr, not 2 orders of magnitude higher.

Edited by tater

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1 hour ago, tater said:

I bolded your figure. That's 120 mSv/year. A normal dose here on Earth is 3 mSv/tr. That's 40X too high.

We're in a colonization thread, not a mission to Mars/Moon thread. We know humans do OK at some dose rate that is maybe high altitude Earth. But regardless, it's on the order of 3 mSv/yr, not 2 orders of magnitude higher.

Titan has a nice thick atmosphere and natural protection from radiation. Resources too. Why not set up a Colony on Titan. Seems like a much better spot to pitch tent than radiation baking Mars.

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2 hours ago, tater said:

Earth radiation levels are about like 1,000g/cm2 of radiation shielding in space. 2-3 meters deep of lunar regolith is about 400 g/cm2. This is adequate for some level of protection, but inadequate for flares.

Numbers I see for loose regolith are on the order of several meters deep.

You could greatly lessen this number if you could copolymerize the substrate with a hydrogen rich plastic. Might even be good to have embedded boron, lithium or berylium. The ideal of slowing down cosmic radiation is to have a collision partners which are light enough to take alot of the energy out of the moving particle. If you take out energy they become less relativistic (they age more rapidly) and shower more quickly. Its not just substrate, if you can select from within the substrate the lightest elemental components . . . .hydrogenate these components . . . .one could make the shielding more effective.

Short term .   you place a Cylinder on the planet, connect it to adjacent cylinders and you bury the center one in as much substrate as the structure can withstand. As you say starting from a fresh crater of smallish size is a good place to start, but in the short term you want quantity is more important than quality. Robotics are the answer here, move, elevate, dump.

I don't see storage of hydrogen cylinders on top of the facility as a viable option; not at least until someone can find a source of water that could be used for electrolysis that would exceed the biological needs of a Lunar or Martian colony.

 

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30 minutes ago, Kerbal7 said:

Titan has a nice thick atmosphere and natural protection from radiation. Resources too. Why not set up a Colony on Titan. Seems like a much better spot to pitch tent than radiation baking Mars.

While Mars is certainly not the greatest target for colonization, I wouldn't say Titan is, either. For one, there's a factor of distance. It orbits Saturn. It will take quite a long time to get there. Not only that, but the atmosphere can be an issue. Being a very cold, dense atmosphere, it can easily take heat away. Although that may not be a serious issue... the distance from the sun and the haze prevents effective use of solar arrays, so you'll need reactors, which would have to be designed for that environment. Beyond that, there's the low gravity. Mars has that problem to an extent as well. We have virtually no data on low gravity's effects on child development.

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4 hours ago, Bill Phil said:

We have virtually no data on low gravity's effects on child development.

Have some centrifuge cities.  You can have tilted rings that spin to combine local and centrifugal gravity.  They would be much more costly than normal stationary habitats, but they might be nessasary for pregnancy and infants.  

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1 minute ago, DAL59 said:

Have some centrifuge cities.  You can have tilted rings that spin to combine local and centrifugal gravity.  They would be much more costly than normal stationary habitats, but they might be nessasary for pregnancy and infants.  

While definitely possible under the laws of physics, that's impractical for a few reasons. They'd need to be big, and that means that they'd be hard to build. Not only that, but they'd need to be built on another planet. It's possible, but impractical, at least for now. Things like advanced bearings and maybe magnetic levitation might be necessary. At that point you might as well avoid building the thing on a planet or moon's surface and just do it in orbit.

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59 minutes ago, DAL59 said:

Have some centrifuge cities.  You can have tilted rings that spin to combine local and centrifugal gravity.  They would be much more costly than normal stationary habitats, but they might be nessasary for pregnancy and infants.  

This makes a colony a non-starter, IMO.

Might as well make them in space, there is no reason to put centrifuges at the bottom of a gravity well, that's insane. A precursor to a colony would be testing mammal embryology at 0.38g (for Mars).

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3 minutes ago, tater said:

This makes a colony a non-starter, IMO.

Might as well make them in space, there is no reason to put centrifuges at the bottom of a gravity well, that's insane. A precursor to a colony would be testing mammal embryology at 0.38g (for Mars).

You don't have to do that if you have centifuges in space.  Plenty of raw materials form phobos to build a station.

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20 minutes ago, DAL59 said:

You don't have to do that if you have centifuges in space.  Plenty of raw materials form phobos to build a station.

Orbital colonies make plenty of sense.

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9 hours ago, tater said:

I bolded your figure. That's 120 mSv/year.

No.
25 g/cm2 is 120 mSv/year.

Upd. made wrong calc below, overestimated the thickness. Sorry. Corrected.

Doubling the thickness will decrease the dose proportionally.
You have to have 50 g/cm2 to get 0.12*(0.12/2) = 0.0072 Sv/y = 7 mSv/y.

Official limits are:
nuclear plant personnel = 5 rem/y = 0.05 Sv/y = 50 mSv/y
civilians = 0.5 rem/y = 0.005 Sv/y = 5 mSv/y

So, 50 g/cm2 fulfils the requiremenets for heroes and nearly does this for civilians.

Density of both regolith and concrete is ~2.5 g/cm3
50 / 2.5 = 20 cm.

So, with 10 cm concrete roof and a 10 cm layer of regolith on top (it is necessary to protect the concrete from micrometeorites), you completely meet the requirements even for civilians.
(Also better have the regolith on top to replace it from time to time when it gets activated).

The house is protected from down by the planet, so dose / 2.
And in Henan design it's protected from sides - by neighbors. So, dose / 4.

With such design you can have 8..10 cm of concrete with 10 cm of regolith on top.

Though anyway the concrete roof will be even thicker than 10 cm, just for construction.

***

Use triple quartz UV-semitransparent glasses in mini-domes, with gas between the layers.
The lower two glass layers are a thermos an unlikely will broke at once.
The outer (upper) layer is expendable, you'll be replacing its glasses from time to time on their scratching by meteorites.

~15 cm in total to protect from radiation even in the patio.

Edited by kerbiloid

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7 hours ago, PB666 said:

You could greatly lessen this number if you could copolymerize the substrate with a hydrogen rich plastic.

Works only against primary protons, not against gamma.

7 hours ago, PB666 said:

Might even be good to have embedded boron, lithium or berylium

Rhodium and palladium are also nice.
But local dirt is good enough.

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Does it scale that way? All my docs on lunar bases from civil engineers talk about meters of regolith. The 3 mSv figure is from NASA.

Solar event particles will not be significantly diminished by 50cm of regolith, even a meter might not be enough for a flare event.

I keep seeing reference to needing 700-1000g/cm2 (~5 meters of regolith) to stop all non-heavy nuclei GCRs. Clearly there is no need for zero exposure, so under 5m.

Most are discussing short term exposures, as well. Meaning something like a 1 month stay on the surface, not living there for years, so they use higher dose limits (nuclear powerplant worker, etc).

G5NHP.jpg

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1 hour ago, tater said:

Does it scale that way?

?
It works for reactors and  nuke vaults, why shouldn't for lunar bases?

1 hour ago, tater said:

The 3 mSv figure is from NASA.

5 mSv is official medical limit for civilians.
Though, 20 cm of concrete + 10 cm of regolith anyway is much thicker than both 3 or 5 mSv.

1 hour ago, tater said:

Solar event particles will not be significantly diminished by 50cm of regolith, even a meter might not be enough for a flare event.

ESA study considers solar events up to two days long.
They have a 50 cm space between walls filled with water and food (density 1 g/cm3) as a built-in vault.
So, have a 1 ft thick roof. (Anyway irl it probably will be even thicker just for construction reasons.)

1 hour ago, tater said:

I keep seeing reference to needing 700-1000g/cm2 (~5 meters of regolith) to stop all non-heavy nuclei GCRs

Then DSG crew is dead.

Reactor walls are ~6 m thick, this is 1800 g/cm2.

Upd. Probably I understand.
700..1000 g/cm2 would stop all GCR particles.
Lunar base doesn't need to stop every photon and proton. It's enough to decrease the dose rate below the medical limit.

Upd 2.
Couldn't see your picture first time.
Now I've seen it. It sounds rather strange.

Btw they underestimate regolith density.  1000/770 = 700/540 = 1.3 g/cm3.
From wiki:

Quote

The density of regolith at the Apollo 15 landing site averages approximately 1.35 g/cm3 for the top 30 cm, and it is approximately 1.85g/cm3 at a depth of 60 cm.

So, 1.35 is just the porous upper layer. Normally lunar ground is 1.85 g/cm3 dense.
So, their numbers should be multiplied 1.35/1.85 =0.73.
Concrete is ~2.5 g/cm3.

So, their "5.4 meters" are in fact 2.5 m of concrete + 1 m of regolith.

The overall dose for the 1956 flash is 0.14 Sv, i.e. 14 rem.
Medical limit for a single accident is 25 rem.
So, it's acceptable to get this dose without any protection at all for a personnel, but after that they should be returned to the Earth for medical assistance and further reabilitation.

Currenly it is 2018. So, this flash is 1..2 times per century and lasts for several hours..two days.

So, it's enough to have a vault room in the dungeon with additional 1..2 meter of concrete above the head to make this risk negligible even for civilians.
They will use it once per decade.

But they need such vault anyway at least due to nuclear powerplant right aside the town.
So, after "Radiation alert" signal the lunar citizens just have to arrive to the closest vault and hide.

Edited by kerbiloid

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You don't need solar flare rated shielding on the entire habitat. You only need a bunker that can fit the population for a couple of days, and only that bunker is dug deeper.

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And if the whole town is in fact a, say, wide 4-storey building with two lower storeys technical and two upper storeys living (like 2-storey appartaments: ground floor - hall, kitchen, patio;  and minus one floor - dormitories), then the vault can be just a room in the lowest technical storey, between storehouses and life support equipment.

Also that additional 2 meters can be a pillow under patio. Then 3 storey is enough.

P.S.
Patio are not a luxury.
Don't forget that all of them are either inside a room, or inside a spacesuit. No UV.
So, either patio, or solarium. The former is better.

P.P.S.
I would suggest to make the ground floor as trapezoid in section (for strength purposes).

Then the patio will be like an overturned trapezoid: glass ceiling wider than floor.
This will extend the angle from which the Sun is visible and gives UV.
 

Edited by kerbiloid

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