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[TempAcc]

Why the hell is Brianna Wu running for congress.
Has amurica truly entered the age of ridic politics with Trump?
Inb4 alex jones for senator.

[LordBaal]

On the health issue. Thing is nobody really knows how such low gravity would affect us. Currently we know very well what both 1g and (almost) 0g do over prolonged periods of time. But no one knows for sure what anything significant in between 0 and 1 would do. We have good guesses but nothing has been proven just yet.

On the energy one, considering the night/day cycle on the moon the only place where is practical is on the poles.

[sluissa]

But then, why launch from the Moon instead of constructing your sci-fi scale interplanetary ships in orbital space directly?  On the Moon, you're still sitting at the bottom of a significant gravity well, but you don't have enough gravity to actually ensure the health of your local workers without additional measures.  You don't have the mineral resources of Earth, and you can't tap a convenient NEO that may have the heavy elements you need in abundant supply much more easily on the Moon than you could on Earth.  You also get to worry about that lovely sharp lunar dust getting into everything; your entire construction area needs to be safed against it unless you want to worry about damaged gaskets, sealing, wires, fine lenses, and so forth. 

EDIT:
Ah, at any rate, my own thoughts.  I see the moon being primarily a resource-extraction industry at the very most, albeit one primarily focused on relatively light elements: helium-3, oxygen, water, and (on the heavier side) aluminum and maybe iron.  It's generally believed that short of a trip out to the outer planets, the Moon is the most convenient source of helium-3 in the inner system.  This, however, requires effective cold-fusion to make any use of ³He; most present uses for the isotope aren't really worth the cost of going to the Moon and back.  Even as a power source, it's questionable if it's worth the cost.  A space economy is likely going to be centralized in Earth orbit with possible occasional forays to near-Earth objects or even the asteroid belt for the foreseeable future.  While resource extraction is going to be major due to the wealth of accessible resources available in certain types of asteroids, zero-G manufacturing does have significant promise.  Power generation is also a possibility: without gravity, tremendous solar arrays can be constructed without the structural support necessary on Earth, and without occlusion by weather or the planet itself, can operate continuously, but the question then becomes if efficiency losses from power transmission from orbit to the ground outweigh this.

Here's the thing. Yeah, you could build things in orbit, but where are those resources coming from? Asteroids could work, if you could get those back, but most of them are WAY out there. If you're launching from earth... well, we're already doing that, and it's expensive and slow. (See ISS).

The moon has resources, even if it's just iron. Hell, even if it's just rock. I don't know about the strength of the material or how it'd work in space, but if you just carved out a cylinder from lunar basalt, weight be damned it'd be cheaper to launch that from the moon than likely any conventional launch from earth to get ANYTHING of equivalent size into orbit.

Build a magnetic catapult on the surface and you've got most of the way into orbit. Just a small amount of thrust to circularize and you could launch almost anything for only the cost of the electricity.

The only problem is infrastructure. Self replicating machines would be my choice but . Launch a handful, they build more, then they build manufacturing structures and/or habitat for humans.

[Sheb]

Why the hell is Brianna Wu running for congress.
Has amurica truly entered the age of ridic politics with Trump?
Inb4 alex jones for senator.

Who is she?

[Reelya]

Why the hell is Brianna Wu running for congress.
Has amurica truly entered the age of ridic politics with Trump?
Inb4 alex jones for senator.

Who is she?

She's one of the activist game devs who got embroiled with the GamerGate idiots.

[Gentlefish]

Guys pls take it to not the space thread.

[WillowLuman]

Affirmed: that has nothing to do with space. Take it elsewhere. Also, I'd appreciate it if you could edit those last few non-space posts so that no one feels tempted to respond with more off-topic and potentially volatile things. Thank you.

[Culise]

Here's the thing. Yeah, you could build things in orbit, but where are those resources coming from? Asteroids could work, if you could get those back, but most of them are WAY out there. If you're launching from earth... well, we're already doing that, and it's expensive and slow. (See ISS).

The moon has resources, even if it's just iron. Hell, even if it's just rock. I don't know about the strength of the material or how it'd work in space, but if you just carved out a cylinder from lunar basalt, weight be damned it'd be cheaper to launch that from the moon than likely any conventional launch from earth to get ANYTHING of equivalent size into orbit.

Build a magnetic catapult on the surface and you've got most of the way into orbit. Just a small amount of thrust to circularize and you could launch almost anything for only the cost of the electricity.

The only problem is infrastructure. Self replicating machines would be my choice but . Launch a handful, they build more, then they build manufacturing structures and/or habitat for humans.

You're correct that most asteroids are not near Earth, but that's because of the sheer amount of asteroids out there.  There are more than 14 thousand near-Earth asteroids, just counting those that we know about.  There are 1786 potentially-hazardous objects, which are defined as asteroids or comets that approach the Earth to within 0.05 AU and have a diameter of at least 100-150 metres and should probably be considered for redirection at some point even if they don't contain useful resources; there are even more that are smaller than that.  It's become known in the last decade as well that asteroids are regularly captured by the Earth even without human involvement before eventually leaving Earth's gravity well for the Sun, such as 2006 RH₁₂₀, whose 2006 capture sparked interest in this phenomenon.  Estimated yields from even a single such S-type asteroid can contain tremendous amounts of metals, including not only iron, but also those that cannot be found easily on the Moon at all such as platinum or gold for electronics.  You really don't need *that* many, at least in the timescale of an early space economy where the Earth-Moon system is still the be-all and end-all of exploitation  with Mars at the most distant hinterland (Earth itself will likely always be a metropole for the solar system, short of terraforming Venus/Mars, but that's another question entirely). 

Besides, it seems like it'd be quite cheaper to lift the materials off the moon (whether it's with your fancy magnetic catapult or with, going one further, a space elevator; you can make one of the latter far more cheaply on the Moon than on Earth) and build your spaceships in orbit, where they never have to deal with more than microgravity and can be engineered solely to handle whatever forces may be generated by their own engines, rather than building them on the Moon itself where they must be built to support their own weight (which is significant even at a sixth of Earth standard) in addition to their thrust forces, where they have to be lifted off against Lunar gravity once manufactured, and where Lunar dust would be an endemic problem (especially if they're sufficiently large that you can't build them in a sealed chamber).  For ships that don't necessarily have massive instantaneous forces applied to them, such as anything lifting off from the Earth, it's more efficient to build in microgravity directly rather than operating via intermediaries.  This also, unlike Lunar colonies, allows for the possibility of allowing the construction workers to live in a rotating station that can generate full Earth gravity.  Finally, on the Moon, you gain none of the unique benefits of microgravity refining.  I can see some manufacturing done on the Moon, but I would expect it to be bulk goods, refined metals, fuels, and certainly relatively little that requires materials not found on the Moon or enjoys particular benefits from microgravity manufacturing (such as electronics or semi-conductors).  Ceramics and concrete would be convenient, for instance; those materials are found in abundance on the Moon. 

[smjjames]

You can dig underground on the moon. The biggest risk for significant times off of earth is radiation and the most cost efficient way to deal with radiation threat is to dig deep. Lunarcrete is cheap because it's in situ.

Alternatively, one could use lava tubes, which would be HUGE on the Moon, big enough to fit a city inside, so, plenty of space. The tricky part though is finding one.

[WillowLuman]

Just use ground sonar?

[sneakey pete]

I find it intriguing that suddenly people are calling for NASA to just cancel the SLS because spacex can do it instead.
However the spacex module to be sent would weigh approximately 1/3rd of the weight of the payload sent to the moon by the SLS (according to a source I read. validation of that would be nice?) because it doesn't have to land or even achieve orbit. So hopefully people figure that out eventually.

Though it does raise the question. If they (spacex) start doing their mars shuttle thing in the next decade, would they then just use it to ferry back and forth stuff to the moon while they wait for transfer windows? That would surely have the ability to get to and land on the moon, and often.
Moonbase anyone?

[Starver]

When it comes to Moon materials, best to do your mining and processing on the Moon (excepting where you'd like a gravity-'free' environment for consistency of product, although the lack of convection/stratification can be an engineering challenge as well in refining) then Mass-Drive finished girders/etc into space, rather than launching ore for space-separation (definitely needing centrifuge technology at varioys stages of separation).

But it'll be a process needing some thought, once we have a better idea of what can be mined and processed from there and other places.


BTW: Just listened to two comedy radio shows about space.  The first is intentional (a repeat, heard it before several times) called Helen Keene's It Is Rocket Science. Short, snappy and scientific if slightly satirical. If you're geoblocked from listening, outside the UK, I'm sure you've got enough information to find something that isn't, as well as anyone who wants to find the other series(/seasons) before this one.  A quarter of an hour probably isn't too long to get an idea before tracking down other episodes and 'series'.

Then, this morning, there was In Our Time, on the Kuiper Belt. Not any actual comedy, the basic conceit of the series (in both senses of the word) is that cultural-all-rounder Melvin Bragg (much parodied, for many decades) gets some experts in a scientific, historical, philosophical and/or other field and he tries to shepherd them (obviously with not-always-accurate notes he makes during a preparatory discussion, off-air) into explaining the topic-of-the-week in an everyman-level of understanding (at least as its grounding, then stretching things so that the complexities of Fermat or Solipsism or the life of some obscure Egyptian Monarch are at least touched upon), all in 45 minutes of apparently live-and-uncut discussion (30 minutes in the edited down evening repeat.

So, today the subject was, as indicated, The Kuiper Belt. And the experts were decent and proven stalwarts of broadcasting (sometimes there's an expert on Mediæval History who definitely knows his stuff but has a hard to ignore verbal tick/radio-shyness/tendency to punctuate his speech by a fidgety tapping that gets picked up on the mike).  And it went well.  But the experts did miss a few better answers to "so why are the KBOs going so slow?" (Bragg, more of an Arts person, thinking this was important, the experts obviously thinking it was just self-obvious) and got dragged into telling us of F=Gm₁m₂/r² when they could really have just said that if they were going significantly faster they just wouldn't be in the Belt for long! (Also related, about stability of orbit, not that these things were stable, just that they are stable enough to still be there...)

And then there was the "temperature at the Belt" (presumably its objects, not the space, although it's sort of arguable that it's the same).  They knew their figures but got tied up about units.  "About minus 220 Kelvin,"/"minus 600 Celsius"/"No, wait, that's wrong, umm..." 

Anyway, there's a whole set of podcast categories for this programme, probably available worldwide, and here are the direct low and high quality versions of this episode, if you feel like a listen yourself after my 'recomendation'. More of an acquired taste, I think, but you may end up learning more about Nietzsche or gin or penicillin (not necessarily in that order!) if you wander through some other of the many (just exceeded 750!) prior episodes.

[smjjames]

So... SpaceX just announced they're gonna send two private citizens on a trip around the moon... Next year.

Hours beforehand, NASA announced they're considering putting people on their currently planned as unmanned capsule test around the moon... Next year.

Next year could be great.

Speaking of space travel, something I saw in Science Daily: https://www.sciencedaily.com/releases/2017/02/170227152338.htm (has some interesting sidebar stuff too). I don't know if the Apollo astronauts suffered vision problems, maybe they weren't out long enough for changes with the eyes to take effect. However, with space tourism starting, it's going to be more important to figure things out. Also, we don't even yet know what happens to the body in extended low gravity situations like The Moon or Mars, we know what happens in zero (micro) gravity and normal, but nothing about in between. So, every human we send into space is gonna be a gunea pig for decades (and perhaps a century or two) to come.

[Starver]

You remind me that I recently saw this, about rocky material in a binary ('Tatooine'-style) system...

[smjjames]

You remind me that I recently saw this, about rocky material in a binary ('Tatooine'-style) system...

It'd be bigger news if we found it in a young system (or at least one which hasn't had either of it's stars get to the white dwarf phase) because that one is a white dwarf (a stellar corpse, if you will) and a brown dwarf, so, it's effectively a dead solar system. Though it doesn't mean that planets can re-form or perhaps the cores of gas giants survive as we've found a bunch of pulsar orbiting planets as well.