Can Humankind Establish a Supply Chain in Space? (arxiv.org)

Long-time Slashdot reader RockDoctor shares a new paper by NASA planetary scientist Philip Metzger, "detailing a roadmap for humanity to take control of the Solar System in order to solve problems on Earth" by utilizing the resources that are already on the moon. In a 2013 paper, Dr. Metgzer wrote: "[B]ootstrapping" can be achieved with as little as 12 metric tons landed on the Moon during a period of about 20 years... The industry grows exponentially because of the free real estate, energy, and material resources of space. The mass of industrial assets at the end of bootstrapping will be 156 metric tons with 60 humanoid robots or as high as 40,000 metric tons... Within another few decades with no further investment, it can have millions of times the industrial capacity of the United States...
Dr. Metzger wrote in 2013 that "This industry promises to revolutionize the human condition." (See RockDoctor's original submission for more details.) While Metzger now notes that "It will require a sustained commitment of several decades to complete," his new article points out that a lunar supply chain outpost "will cost about 1/3 or less of the existing annual budgets of the national space programs," thanks to advances in both robotics and artificial intelligence, and will help humanity develop renewable energy and greatly expand the availability of other limited resources.

Comments

Yes

[NotInHere]

a matter of when not whether.

Re: Yes

[BarbaraHudson]

Short answer: no.

Long answer: no, not going to happen. The will and commitment are not there, the "free power" arguments are bs, we don't know where (or even if) the needed resources exist in viable quantities or concentrations, human colonies are a death sentence to anyone living there permanently (ignoring the too-low gravity and the radiation, even a minor "oops" will kill you), and at the rate we're avoiding meeting even our moderate climate change goals, we'll have a massive depopulation or extinction event long before that.

Re: Yes

[K. S. Kyosuke]

Why humans? Who says it won't be our non-human successors?

Re: Yes

[DanielRavenNest]

I think you are being too pessimistic, Barbara.

Space industry as of 2015 was $335 billion in economic activity ( see page 7 of http://www.sia.org/wp-content/... ), with about 1400 operational satellites in total. We don't have a way to effectively repair or refuel these satellites. When they stop working, we have to replace them at great expense. Saving money or increasing profits provides plenty of "will and commitment" to build the first generation of space mining and production. This would start with propellants, since just about every satellite uses them, and they are a simple product to make.

> we don't know where (or even if) the needed resources exist in viable quantities or concentrations

On the contrary, nearly all satellites operate on solar energy, so we know that is feasible. The total solar flux passing closer than the Moon is equal to the whole world's fossil fuel reserves *every minute*. That's more energy than we know what to do with, provided we can tap it economically.

Meteorites are pieces of asteroids that hit the Earth and survived re-entry. So we are able to examine those in detail, and then infer the composition of asteroids still in space by comparing spectra. For a handful of asteroids, and the Moon, we have visited by scientific missions, or in person, and gotten more direct information. So, for example, we have detailed geologic maps for the Moon ( http://www.lpi.usra.edu/resour... ) and are building up our knowledge of other bodies.

> human colonies are a death sentence to anyone living there permanently

I will set aside the fact that the human condition has a 100% mortality rate so far, and that a minor oops driving to work will kill you on Earth. But I helped design and build the Space Station, and it's been occupied for 15 years now. Think of it as a proof of concept. A space colony in orbit or on the surface can deal with gravity by rotation. On the ground that means a merry-go-round or racetrack setup that people use for as many hours as required to maintain health. Bulk rock is easy for surface locations, and not so hard for orbital ones. Enough thickness will provide good shielding. Most illustrations of space colonies are "artist's concepts" and don't address safety in the way engineers building bridges and skyscrapers have to. A real colony would have multiple layers of pressure shell, compartmentalization, emergency shelters, and other safety provisions. Yes, accidents and failures will happen, but we live with fires and natural disasters on Earth. The question is can you bring the risks down to a comparable level as on Earth. I think the answer is yes.

> at the rate we're avoiding meeting even our moderate climate change goals, we'll have a massive depopulation or extinction event long before that.

We are installing over a hundred billion watts of solar and wind capacity worldwide this year. Coal use has dropped by a third in the US in the last 10 years. Things could move faster, but when oil states like Saudi Arabia and Dubai are installing renewables, it should be obvious change is happening ( http://www.pv-tech.org/news/sa... )

Re: Yes

[Applehu Akbar]

The will and the commitment are there in the private sector, which is willing to tolerate far more personal risk than the public sector and is not saddled by the 'priorities' argument.

Re: Yes

[NotInHere]

the "free power" arguments are bs

Its bs only in some regards. If you are in an environment where engineering doesn't target

we don't know where (or even if) the needed resources exist in viable quantities or concentrations

So let's find out! If we don't try we won't win.

human colonies are a death sentence to anyone living there permanently

How is that different from life on earth? You die here too. Yeah, maybe life expectancy in space is lower, but it was low on earth as well: just think of the stonemen, they had a hard life having to fight for survival. Thanks to civilization, we easily forget that earth is a harsh place. Of course, space will have its own challenges, and it IS a rougher place than earth without doubt, but I doubt that the challenges can't be mastered.

and at the rate we're avoiding meeting even our moderate climate change goals, we'll have a massive depopulation or extinction event long before that

We live in dangerous times for our civilization, agreed. That's why we need a backup in space. Maybe just putting a few domes with humans inside on the bottom of the oceans and somehow powering them with e.g. geothermal or nuclear fusion or whatever would do the job as well, could help us survive meteorite impacts or similar things, but idk, space is a good option as well. It just needs to be self sufficient and not depend on the atmosphere of the earth to be transparent to sunlight (which it isn't when a volcano exploded or a meteorite crashed into our planet, etc) or stuff like that

Re: Yes

[no1nose]

I have to agree. We can barely get people to work on Earth on time. Imagine the delays in getting supplies to space colonies. Hopefully, they can grow potatoes like The Martian did.

Re: Yes

[Anonymous Coward]

Short answer: no.

[citation needed]

Long answer: no, not going to happen.

[longer citation needed]

You know, or maybe you do not know, but gosh darn it, you sometimes appear to be an enormously arrogant twit. More than a little full of yourself.

I strongly suggest that you read carefully what someone who knows far, far more about this subject has replied to you, and others, on this topic.

If you lose the arrogance, you might even learn something. That would do you good.

Re: Yes

[ArmoredDragon]

GP is just overly sheltered to be honest, and kind of lacks perspective.

The perils described don't really sound that different from mining in ages past. Consider, for example, how dangerous nitroglycerine is to handle; so dangerous that most people refused to handle it. And yet it was basically all that was available for use in mining operations for a very long time, and mining remained profitable and continued anyways because people would handle it if the pay was right. And among other things, the job was often out in remote areas, so indeed the workers were quite isolated, cave-ins were a very real risk, and work shifts were so deep underground that it might be days before you see daylight, and there was so much soot and dirt in the air that your lungs would age very quickly.

But again, people would do this anyways because it paid a lot more than any other work they could have done.

With all of this talk about automation taking over jobs, and if that does result in economic hardship, you'll have an easier time getting people to do dangerous off-planet work than you might realize.

https://www.youtube.com/watch?...

Re: Yes

[dbIII]

Longer answer - China and Russia care less about the problem you have identified with living in space for long periods of time. It remains to be seen if they have the will or commitment to take the steps but colonists with a reduced lifespan are not seen as a showstopper.

We've been there in the west not so long ago and may still be in that situation in some places - dangerous jobs were not so uncommon only a couple of generations back. My grandfather worked at a mine where apparently nobody lived past fifty. Attitudes have changed but may change back.

Re: Yes

[K. S. Kyosuke]

I see several problems with this. First, you say that "we wouldn't give a shit about what they would or wouldn't accomplish". That problem is, many people obviously do give a shit. Second, you say that "they don't exist. They may never exist." And you're completely, absolutely right. The problem is, we don't know for sure that they can't ever exist. And the future is very, very long. In fact, unless we manage to wipe ourselves out, it's going to be orders of magnitude longer than the even the whole current history of the human civilization. We've only had organized civilizations for a few thousand years, and even the human from a few hundred years ago wouldn't recognize today's world. Just the world half a millennium from now on will be a very different place, not to mention the world thousands or tens of thousands of years from now on. How different it will be is anyone's guess. The one thing we can be quite sure about, even if we don't engage in any sort of trans-humanist effort, is that the evolution itself hasn't stopped. So the idea that we can have any inkling of what is actually going to happen is a delusion. All I'm claiming is that if any moving of technological civilization outside Earth will happen (without claiming that it will happen), given the massive changes that have already taken place, there's absolutely no reason to a priori assume that humans will be required for it, especially if it will happen a very long time from now. You haven't refuted that with your tirade.

Re: Yes

[BarbaraHudson]

The Germans would disagree with you (and they're not the only ones). Even aircrews within the protection of Earth's magnetosphere flying at high altitudes receive higher radiation doses (the FAA classifies flight crew as radiation workers, and on average they receive twice the radiation exposure of someone working in a nuclear power plant). >p>The moon doesn't have the protection the earth does. And it looks like the Apollo moon walkers have a much higher rate of radiation-induced cardiovascular disease than those who stayed within the earth's radiation shield.

Re: Yes

[BarbaraHudson]

Why would they send humans to explore space when robots can do (and are doing) the job?

Re: Yes

[BarbaraHudson]

Totally irrelevant to the original question, which was "Can Humankind Establish a Supply Chain in Space". Humans aren't fit for space. Robots, on the other hand ... they're the only way to fly :-) It's also why any aliens we encounter won't be biological.

Re: Yes

[RockDoctor]

Bulk rock is easy for surface locations, and not so hard for orbital ones. Enough thickness will provide good shielding.

For radiation shielding, yes.

To a first approximation, what matters is mass, not composition. We live at the bottom of an atmosphere equivalent to about 10m of (sea) water. You can achieve that shielding with about 3m of compacted silicate dust. Or about 2/3 m of lead. Still adds up to much the same mass, so you use the most available stuff.

Most illustrations of space colonies are "artist's concepts" and don't address safety in the way engineers building bridges and skyscrapers have to. A real colony would have multiple layers of pressure shell, compartmentalization, emergency shelters, and other safety provisions.

My personal preference for shielding is to make lots of plastic bags, fill them with salty water melted out of your pet asteroid, or coarse or fine dust filtered from the water as the first stage in your processing. Attach bags to outside of space ship, in overlapping layers. Micrometeorite punctures a dust bag - big fucking deal - you've a thousand more around you. Punctures a water bag - it's already frozen to ice ; big fucking deal, as above.

Started building metal-rock paels for the next chunk of your space station? Well, start building it around the outside of your existing shield, maybe moving dust bags off so there are only water bags in between the layers. Then puncture the water bags and use it for leak detection, or just to mop up the dust. Eventually you have a shell with no major leaks, inside which you can start to build your next bit of living space, while pumping the remaining water bags out to add to the shielding.

It's do-able. Not significantly more hazardous than working on oil rigs (which I've done for nearly 30 years).

Re: Yes

[BarbaraHudson]

Nonsense. The private sector has become dependent on governments making the general population absorb the risks for th e"too big to fail." It would have cost less to bail out every single homeowner in the housing crisis than it did to bail out the banks.

And then there are subsidies and tax breaks ...

Look at Apple - sitting on a cash horde it doesn't want to pay taxes on and won't repatriate until it gets a tax holiday, reduced to removing a headphone jack as "innovation".

Re: Yes

[BarbaraHudson]

I don't see anyone, least of all you, offering citations to prove I'm wrong. So take your [citation needed] and stick it.

Re: Yes

[ArmoredDragon]

We still live in a world where mining isn't done by robots, and it probably won't be by the time any of this comes to fruition. Maybe, who knows. The best we can do at this point is speculate.

Re: Yes

[strikethree]

But I helped design and build the Space Station...

Thank you. This makes you somewhat of a hero in my eyes.

Re: Yes

[BarbaraHudson]

I wrote the robots are doing the space exploration, not mining. And yet, even back in the '60s the Surveyor spacecraft were prospecting on the moon, and did some soil analysis. Curiosity drilled 2-1/2" to extract and analyse a "core sample". Will this ever be scaled up to actual mining? Certainly better than the chance of humans doing so - we're becoming redundant in so many jobs.

Re: Yes

[david_thornley]

You're listing problems that will be encountered, some that are already fixed, and claiming they will never be adequately solved. That is a fairly strong statement that we're not in general agreement with and is definitely not self-evident. If you want your post to convince anyone you need to provide more support for it.

Re: Yes

[BarbaraHudson]

No, I don't. The burden of proof is on the person making the extraordinary claim.

Re: Yes

[rtb61]

Are China or Russia willing to make that effort to get from the Earth, to a major moon base and from that base to the rest of solar system and then out into the galaxy, not really. Now a combined China Russia commercial space program with their own individual military space programs, now that's a whole different story and most likely where the future of humanity in space will come from. Once they have settled down that combined space program (being driven by American aggressiveness and threats of attack from space by the US space program), they will likely invite others and that's when that program will really kick off leaving the US behind and the EU undecided about what the hell to do, at least to start with.

Russia and China would be far better squeezing down on their military program to make it as small and cost efficient as possible and invest that money on a future in space, ultimately the secure high ground, well, when it comes to other mud monkeys of course.

Re: Yes

[david_thornley]

The "extraordinary claim" that you see is that we might be able to establish an industrial base off-planet someday. In what way is that claim extraordinary?

Re: Yes

[Coren22]

I can't get TFP without paying for it, so I can't say for sure. It looks like you might be arguing against a strawman. The paper's abstract specifically talks about AI and robotics, so what is to stop humanity from building a supply chain with teleoperated robots shipped to the moon?

You are arguing against humans mining on the moon when clearly our robots can do it now with minutes of lag between commands (Mars rovers), so in the future?

Re: Yes

[BarbaraHudson]

Because we don't have the tech, and we probably won't last long enough to develop it before the wheels start coming off everything. Business certainly isn't going to do it - that requires investing tens of trillions of dollars for something without a payoff within the lifetime of many of the people you'd want to pony up the money.

Re: Yes

[BarbaraHudson]

our robots can do it now with minutes of lag between commands (Mars rovers)

The lag is a lot more than that, and that's why every move has to be done with extreme planning. And when Mars is on the other side of the sun, forget it. The lag between the between you sending the command and seeing the result is between 8 minutes and 48 minutes. Telepresence? VR? Ain't gonna happen with that much lag.

Re: Yes

[Coren22]

https://arxiv.org/abs/1609.007...

There is your citation, it is listed in TFS, and is apparently a freely available paper (no charge like I initially thought and replied elsewhere to you).

You should write detailed rebuttals of the actual paper instead of speculating on what the paper says, as rebutting human colonies when they aren't even in the paper makes it look like you maybe don't know what the paper was about.

Re: Yes

[Coren22]

I don't even see the big deal about people living there. We currently have a 15 year habitated station with microgravity. The moon at least has way stronger gravity, and is only three days away by a tiny rocket (if I recall correctly from Apollo 13). It isn't like people would be permanently living on the moon, though eventually we might get to that point.

Re: Yes

[BarbaraHudson]

The paper is flawed. It relies on suppositions, none of which have been proven in space. We've had light-out facilities for decades. Big deal. Look at the claims on page 13 that we can rapidly terraform Mars. No, we can't.

We could also rapidly terraform Mars [11]. First, autonomous robotic labor can capture icy bodies in the outer solar system and transport them to enter the Martian atmosphere.

Not in your lifetime. Not in your grand-kid's lifetime. And given the current trends, we'll lose all capability to do that sort of stuff within a generation, same as we already lost the capability to put a man on the moon in the previous one.

Re: Yes

[david_thornley]

"We don't have the tech" is true, but a completely useless observation when it comes to predicting the future. "We probably won't last long enough", even if true, doesn't justify saying "we will never". "Business certainly isn't going to do it" is arguable, but there are other ways to do things than wait for private industry to get around to them.

If I say "we might last long enough to get the necessary tech going with a lot of government assistance", I'm being completely consistent with what you just said, and that contradicts your earlier "not going to happen".

In a word

[Anonymous Coward]

No. I believe that answered your question. You may now close this thread. Have a nice day.

The most expensive part...

[matbury]

...will be getting sufficient supplies of Brawndo, The Thirst Mutilator, to people stupid enough to try to live in space.

Re:The most expensive part...

[DanielRavenNest]

Who needs Brawndo, when you can have Pussy in orbit ( https://www.amazon.com/Pussy-N... )? :-)

In any case, water, carbon, and electrolytes are available in the Chondrite type asteroids ( http://www.sciencedirect.com/s... ), so at most you would have to supply trace nutrients.

Re:The most expensive part...

[no1nose]

Damn. I already commented so I can't upvote. But THIS.

"the free blah blah blah of space"

[Nutria]

Nothing is free, especially in space because of not just the resources but the industrial capacity to create those resources -- and in space you'll need a lot, since not only aren't there any on the Moon, but you need to claw out of a really deep gravity well to get that stuff to the Moon -- required to take advantage of that so-called free energy and material resources.

Re:"the free blah blah blah of space"

[K. S. Kyosuke]

There's one important resource that's really scarce on the Moon, comparatively to what we might want: carbon. Other things I'm not so sure about. After all, Moon is made basically of the same material that the Earth was formed with.

Re:"the free blah blah blah of space"

[Anonymous Coward]

well I was wrong. Turns out not much in the way of carbon. Lot's of iron, titanium, calcium, and surprisingly oxygen. Well we could get our carbon the same way we get loads of it on Earth, Amazon boxes. (I have a pile of them by the front door). What ever you ship up there make sure you can burn the packaging in was sent it in order to break it down into the base carbon, and extract all the hydrogen in the form of water while you are at it.

Re:"the free blah blah blah of space"

[Nutria]

According to this graph, there isn't too much carbon.
https://en.wikipedia.org/wiki/...

https://en.wikipedia.org/wiki/Geology_of_the_Moon#Elemental_composition "Carbon (C) and nitrogen (N) appear to be present only in trace quantities from deposition by solar wind." No citation, so take it with a grain of salt.

Re:"the free blah blah blah of space"

[GNious]

After all, Moon is made basically of the same material that the Earth was formed with.

Slightly more precise, the Moon is made out of Earth's crust, so primarily consists of the lighter materials.

Re:"the free blah blah blah of space"

[K. S. Kyosuke]

Yes, I know, that's why I mentioned it.

Re:"the free blah blah blah of space"

[K. S. Kyosuke]

Oxygen shouldn't be surprising, there's lots of silicon and aluminum oxides there, just like in Earth's rocks.

Re:"the free blah blah blah of space"

[K. S. Kyosuke]

But it also wasn't subject to the same amount of stratification. And if Earth contains more iron at its core, it's not all that useful to us anyway since it's not accessible. Ore genesis didn't take place on the Moon but the surface material seems to be reasonably mixed to not require it. Any exploitation, however, would require very different processes, not just because of the diffuse nature of the source materials. For example, the aforementioned lack of carbon basically excludes smelting.

Re:"the free blah blah blah of space"

[K. S. Kyosuke]

I think you can blame the French for that.

Re:"the free blah blah blah of space"

[c]

After all, Moon is made basically of the same material that the Earth was formed with.

Slightly more precise, the Moon is made out of Earth's crust, so primarily consists of the lighter materials.

What a happy coincidence... the Moon is made from exactly the part of the Earth that humans are most familiar with exploiting.

Re:"the free blah blah blah of space"

[DanielRavenNest]

That's where self-bootstrapping automated production (seed factories) come in.

You build the first ones here on Earth. That's my day job, by the way - building prototype seed factories. The first generation factories are built in moderate environments, like Atlanta where we are working. They produce parts for more equipment, eventually growing to industrial size. They also produce useful products to pay for their upkeep. Eventually you send new seed factories to more difficult locations, like the oceans, ice caps, and deserts. Finally, you tell your collection of factories to build rocket factories and launch pads, and off you go to space.

The starter sets (seed factories) won't be free, but they will be low cost because they are small. They pay their own way after that, by making things people need and want.

> but you need to claw out of a really deep gravity well to get that stuff to the Moon

The actual escape energy from Earth is 62.5 MJ/kg = 17.375 kWh/kg = $1/kg at wholesale electric rates, about what I pay for potatoes. We just have been terribly inefficient about how we get to space.

Re:"the free blah blah blah of space"

[DanielRavenNest]

That's why you want to build in high orbit *near* the Moon, and not *on* the Moon.

The three main types of asteroids (chondrite, stony, and metallic) are all different from each other, and from the Moon, because of their origins and history. In particular, the chondrites have up to 20% water and carbon compounds. You can deliver asteroid rock to high orbit using solar-electric propulsion, which is very efficient. You can deliver Lunar materials to orbit with an electric centrifuge, also very efficient. In high orbit you get sunlight 100% of the time to power your equipment. The Lunar surface only gets sunlight 50% of the time, and the gaps are two weeks long, which is annoying.

> After all, Moon is made basically of the same material that the Earth was formed with.

They started out similar because the Moon is made from debris from the Theia-Proto Earth collison. But the Moon remained hot for a long time due to original collision energy, later bombardment, radioactive decay, and tidal heating when it was much closer to Earth. Because of the Moon's smaller size, it lost most of the "volatile" compounds (anything with a vapor pressure at lava temperatures). They either escaped directly, or were stripped by solar wind particles. So the Earth and Moon are fairly different today.

Re:"the free blah blah blah of space"

[Nutria]

The actual escape energy from Earth is 62.5 MJ/kg = 17.375 kWh/kg = $1/kg at wholesale electric rates ... We just have been terribly inefficient about how we get to space.

Completely ignores that the energy has to be converted to 40,000 k/h escape velocity.

(Don't even mention "space elevator"... https://www.youtube.com/watch?v=iAXGUQ_ewcg)

Re:"the free blah blah blah of space"

[Immerman]

I agree beanstalk-style space elevators are ridiculous for the time being, and there's a real possibility that we may never develop materials strong enough to actually build them on Earth with adequate margins of safety.

  But that's only the most dramatic and convenient kind of elevator, There are many other far more achievable designs being considered, including my favorite, the tumbling cable or wheel elevator, which is potentially *far* more cost effective per launch since it doesn't require actually spending energy for every launch, instead acting as a "momentum battery", imparting momentum to vehicles snatched from the upper edges of the atmosphere, and then reabsorbing it when they return. Even if there's a net imbalance, you can still gradually "charge up" the wheel using radically more efficient ion drives rather than high-power chemical rockets. (Incidentally, such a design also has great potential orbiting the moon, where it could be quite small yet potentially snatch things directly from the surface and hurl them on transfer orbits to either Mars or Venus)

And then there's ideas like airship-to-orbit (http://www.jpaerospace.com/) which if it can be achieved is considerably slower, but also potentially far safer and more efficient than rockets.

Re:"the free blah blah blah of space"

[khallow]

Ore genesis didn't take place on the Moon but the surface material seems to be reasonably mixed to not require it.

You think based on very little evidence. An obvious rebuttal here is that certain ore genesis processes on Earth required volcanism or asteroid impact, both which have happened on the Moon. For example, the nickel deposits of Norilskâ"Talnakh are thought to be formed by sulfur chemistry transferring nickel and other metals into a layer of magma pinned under the Siberia Traps eruptions (which would be in the top ten lunar maria by surface area, if it happened on the Moon instead of on Earth).

The famous Bushveld complex is a concentration of platinum group metals thought to be caused by an asteroid impact melting into a magma body and then selectively crystallized out last as the magma body slowly cooled.

So we have two mechanisms for substantial differentiation and ore genesis on Earth, which would apply just as well to parts of the Moon.

Further, there's direct evidence of significant differentiation possible with the "orange soil" discovered by astronaut Harrison Smith during the Apollo 17 sortie which had high concentrations of titanium (8% by mass) and "rich in zinc" which probably came from late stage volcanism on the Moon's surface.

Re:"the free blah blah blah of space"

[Nutria]

my favorite, the tumbling cable or wheel elevator

I googled, but no joy.

we may never develop ... potentially ... great potential ... if it can be achieved

The pie is great in this one's sky.

it doesn't require actually spending energy for every launch

Let's pretend that doesn't break physics. The lot of energy still has to come from somewhere, be stored somewhere, and be transmitted to the "car".

and then reabsorbing it when they return.

Friction, among other things, will steal a lot of that energy.

Re:"the free blah blah blah of space"

[GNious]

My (limited) understanding is that material on the moon tends to more "mixed" and less layered (also, see above comment about stratification), making mining less efficient. Also, if you're in space, things like palladium group metals might be "easier" to get from metallic asteroids?

Re:"the free blah blah blah of space"

[GNious]

+1 comment :)

I'd observe smelting could be done using electricity - giant solar panels (but...no water to wash them regularly)!

Re:"the free blah blah blah of space"

[Anonymous Coward]

I suspect the "tumbling wheel" is what Wikipedia calls a "skyhook".

https://en.wikipedia.org/wiki/Skyhook_(structure)

The lot of energy still has to come from somewhere, be stored somewhere, and be transmitted to the "car".

Certainly. The energy will have to be used to place the skyhook into the proper orbit, and to accelerate it into tumbling.

Then, if I understand correctly, momentum is stored in the skyhook. Flinging a payload would rob the skyhook of energy, but catching a payload would give some back.

It may not work but I don't think your dismissive attitude is called for. It's an idea that doesn't require impossible materials or new physics. It's beyond our current engineering skills, I think, but it's much more plausible than a proper space elevator. (Disclaimer: I'm not a physics expert and I'm not pretending to be one.)

P.S. I personally think reusable rockets would do an adequate job of reducing launch costs. I could afford to fly from America to Australia, expensive as it is; if each plane could only make a single flight and was destroyed in the process, the cost would be far beyond my ability to afford it.

Re:"the free blah blah blah of space"

[dbIII]

Yes but reducing stuff to get that oxygen is a bit of a pain especially without petrochemicals.

Re:"the free blah blah blah of space"

[dbIII]

Typically smelting is a chemical process so it needs heat and a reducing agent (eg. CO).
Just melting rocks doesn't get a lot done unless you add other rocks.

Re:"the free blah blah blah of space"

[c]

My (limited) understanding is that material on the moon tends to more "mixed" and less layered (also, see above comment about stratification), making mining less efficient.

True, we'd be hunting for chunks rather than veins. On the other hand, digging should be easier, assuming we're cool with strip mining the Moon.

Asteroid mining seems like more bang for the buck in the long term, especially if you're going after specific materials, but I have a feeling that in order to pull it off successfully we'll need substantial infrastructure in space first.

Re:"the free blah blah blah of space"

[K. S. Kyosuke]

An obvious rebuttal here is that certain ore genesis processes on Earth required volcanism or asteroid impact, both which have happened on the Moon.

I was under the impression that lots of them that we took advantage of as a resource-based civilization required water as the transport medium. Obviously, I won't claim that all of them do, even on Earth. I will unhappily admit that I know next to nothing about geology but I'll look up your examples, since I'm still kind of interested in it.

Re:"the free blah blah blah of space"

[K. S. Kyosuke]

The problem is not the energy but the chemical reaction: carbon in smelting not only provides energy but it also binds to the oxygen and takes it away. However, experiments in direct reduction have been undertaken (think something similar to aluminum electrolysis).

Re:"the free blah blah blah of space"

[ColdWetDog]

What a happy coincidence... the Moon is made from exactly the part of the Earth that humans are most familiar with exploiting.

Other people?

Re:"the free blah blah blah of space"

[K. S. Kyosuke]

Solar electric propulsion for hauling stuff around seems rather time consuming. Assuming you have enough water in the asteroid belt, perhaps you could just start hauling ice blocks around using hydrolox fuel and efficient detonation engines? (Isp approaching 500 s and much higher average thrust than any SEP I can think of.)

Re:"the free blah blah blah of space"

[Immerman]

That's the one, and you've got the basic principle down. When it picks something up from the planet and flings it into orbit, it's own orbit decreases somewhat as it loses momentum. Then, when it catches something in orbit to drop it on the planet it gains momentum back. And since it's dealing directly with momentum, it inherently operates at roughly 100% efficiency. Plus, being in orbit it can service an entire great circle on the planet, rather than only a specific region like a beanstalk.

The launching part is relatively easy, as you can tune the operating parameters so that the wheel is essentially rolling across the top of the atmosphere, presenting a momentarily stationary and easily predictable point for pickup, so it could potentially even pick stuff up off the tops high-altitude airships (or increase the speed so that planes can rendezvous). The return trip could be considerably more difficult, since your incoming payload will be on the fastest point of a highly elliptical orbit, and must hit a very specific point, speed, and time to rendevous with the wheel. Still it should be feasible for sophisticated enough automated systems. And if not, well you can still recharge the skyhook with ion drives (or even purely electric geomagnetic drives) instead of wasteful chemical rockets.

Reusable rockets will indeed lower launch costs dramatically, but skyhooks have the potential to lower them another few orders of magnitude. Which would be worthwhile if/when we develop a substantial presence in space.

Re:"the free blah blah blah of space"

[Immerman]

AC is correct about the skyhook being another name. And no, there are actually relatively negligible friction losses because none of the components are moving relative to each other - it's conceptually a big wheel perpetually rolling around the planet in vacuum, with it's bottom just outside the atmosphere. The bottom part is just above the atmosphere and is essentially stationary with respect to it, and the top part is moving at roughly twice the orbital speed - just as the top of your car tire is moving at twice the speed of the car, while the bottom is standing still.

Meanwhile the payloads never move with respect to the elevator - they grab onto the rim of the wheel at one extreme, and let go at the other. Unlike a beanstalk where payloads must be moved along the length. That's one of the great benefits of a skyhook - it's mechanically quite simple, and can be implemented as little more than a single long tumbling cable with "docking clamps" on the ends.

As for "potentially", what word would you suggest for "The science is well understood, and the engineering challenges are within what we can perform now, and we mostly just currently lack the will to actually implement it"? Plus, there's a lot of different ways you could implement it, with different characteristics - my example of snatching things off the surface of the moon is only one possible design constraint(and has its own engineering challenges), and even accepting that as given, the launching results would vary wildly based on just how big the elevator is, and whether you waited to release the payload until you would impart the maximum momentum.

Re:"the free blah blah blah of space"

[khallow]

I was under the impression that lots of them that we took advantage of as a resource-based civilization required water as the transport medium.

Sure, hydrothermal ore genesis is right out. There's apparently very little hydrogen on the surface of the Moon and much of what is there comes from the solar wind.

There's also the possibility of exotic mineral transport processes with chlorine or fluorine gases and compounds according to computer model. That might be a way, for example, to get naturally occurring CFCs and concentration of uranium (via uranium hexafluoride). Not worth speculating more on it since we need real evidence from underground fluid systems rather than a computer model based on really weak assumptions (that the Moon's volcanism had at some point in the past the same gas mix as Earth minus the water).

Re:"the free blah blah blah of space"

[DanielRavenNest]

You can reduce metals directly in a vacuum. The point of the reduction reaction in smelting is to remove the oxygen from the mineral oxides. Carbon can do it because the oxygen has a greater affinity for it than for the metal. But simple heating in a vacuum can break down molecules, and the oxygen pumped away. It's not as easy on Earth, but in space we usually have an abundance of vacuum to play with.

Re:"the free blah blah blah of space"

[DanielRavenNest]

Typical mission times for Near Earth Asteroids in good orbits is 2-3 years. That's going out, grabbing dirt off the surface of an asteroid, and coming back. You can use Lunar gravity assist in both directions, which reduces the acceleration time on the electric propulsion. Current ion thrusters are too small for mining tugs. What you want are 200 kW plasma thrusters, like the VASIMR, and gang up 5 of them for 1 MW total power. That gives you 28.5 N @ 1 AU, sufficient to accelerate a loaded tug (1000 tons payload, 35 tons tug) at 2.38 m/s/day or 868 m/s/year. Most of the time is consumed on the return trip, since the tug is vastly heavier then. On the outbound leg the tug can achieve 68 m/s/day, and do all the required delta-V in a month or so. You would choose asteroids and orbit positions so as to minimize the return leg, and just accept a less efficient outbound leg.

If you think 1 MW is a lot of solar power, modern solar panels the size of the ones on the Space Station (400 square meters) can produce 165 kW each, so six of them in a hexagon around the tug core can do it. By comparison the Space Station has eight main panels.

The main asteroid belt is 1.1 to 2.3 AU from Earth ( https://upload.wikimedia.org/w... ). The "Near Earth" group are by definition within 0.3 AU, so that's the ones you start with. They don't have water as ice, it's too hot that near the Sun. What they have is hydrated minerals, which release the water when heated to 200-300C. An example of a hydrated mineral is kaolinite, which has the formula Al2Si2O5(OH)4. It is a major component of clay on Earth. The OH's are what get driven off in the form of water vapor.

Hauling ice from beyond the "frost line" (2.8 AU), where average temperatures are low enough for ice to be stable, is certainly a possibility, but not for the early years of space mining. It's just too far away. There's lots and lots of water beyond the frost line, because Oxygen is the 3rd most common element, after Hydrogen and Helium, and water is H2O.

Re:"the free blah blah blah of space"

[DanielRavenNest]

Automated factories already exist, and have for many years. What's different about a seed factory is having a planned growth sequence from stored CAD/CAM type design files. They also make useful end-products from the same type of design files, like current automated production follows.

> What cheaper method of getting out of Earth's gravity well can be implemented now?

Enough people are working on that problem (as I used to do at Boeing's space systems division) that a few more people won't make a material difference. Changing how much stuff you need to launch, by bootstrapping production from a starter set, has a lot of leverage, and not many people are working on it. That's why I choose to spend my time on it. No, you can't order a seed factory kit from Amazon at the present time. Neither can you order an iPhone 8 or Galaxy Note 8 yet. They have to be designed and prototyped first, which is what I work on.

> How much cheaper is it than how it's done now?

The potential is to get 98% of the mass of future space products from space. The other 2% is hard to make items or rare elements for which delivering from Earth is easier. The savings are therefore 50x in reduced launch cost, minus the cost and launch mass of the starter equipment. Nobody knows the final cost, because the whole concept is too new. The *potential* is large enough to justify working on it, just like the *potential* of integrated circuits was in 1960. But you have to do the actual work to find out the results.

Re:"the free blah blah blah of space"

[DanielRavenNest]

I've spent 39 years doing space systems engineering, and know more than most about getting to orbit. I *will* talk about space elevators, having taught a class about them last year. But not space elevators "as we know it", to paraphrase Spock. The ground-to-60000 km single cable version that most illustrations show is unworkable, even with carbon nanotubes. A feasible version uses two rotating cables, one in low orbit, and the other in high orbit, with nothing between them but orbit mechanics. Their combined length is under 2000 km, and can be built with today's carbon fiber. You still need a way to get from the ground to half low-orbit energy, but even a chemical rocket can do that, easily, with good design margins, and a single stage.

But even that type of elevator isn't justified yet by traffic rates. A space elevator is "transportation infrastructure", like a bridge or airport. You don't build those for a few trips a month, and neither do you build a space elevator for a few trips a month. But a few trips a month is all the space traffic you can get today. So before anyone thinks seriously about elevators, we have to work through more conventional ways to reduce cost and grow the market.

Re:"the free blah blah blah of space"

[DanielRavenNest]

A 6 km/s tip velocity skyhook is not an optimum design at present. When you do the actual numbers, it comes out closer to 3 km/s, and the remainder is supplied by a ~4 km/s single stage rocket. The totals are not the same because the faster skyhook is larger, and has a higher center of mass. In turn, that means slower orbit velocity. Also, 3 km/s is sufficient to reach high orbits from low orbit, and that's all you really need. Finally, skyhook mass is highly non-linear in tip velocity. Assuming carbon fiber with conservative safety margins, you can allow 150 g-km stress.

The 3 km/s skyhook has 460 km g-km of stress, and mass ratio of one side (center to tip) is exponential in stress ratio, so e^(460/150) = 21.5. Since it has two arms, the total mass ratio is 43:1. The 6 km/s skyhook has 4 times the stress - 1835 g-km. So the total mass ratio becomes 205,500:1, which is unworkably high.

A 4 km/s single stage rocket is *easy* compared to reaching all the way to orbit all by itself, and you can dramatically improve the design margins so it can make many flights. The rocket then bears the same relationship to the elevator as an airplane does to an airport.

Re:"the free blah blah blah of space"

[Nutria]

A feasible version uses two rotating cables, one in low orbit, and the other in high orbit, with nothing between them but orbit mechanics.

Thanks for the info.

Their combined length is under 2000 km

How would you keep them from vibrating and twisting, thus losing "station keeping"?

You still need a way to get from the ground to half low-orbit energy

Wouldn't those forays into LEO slow down the lower cable due to the same atmospheric drag that plagues the ISS?

even a chemical rocket can do that, easily, with good design margins, and a single stage.

Getting a rocket to meet a hook that's rotating at 3000 m/s seems... tricky.

Re:"the free blah blah blah of space"

[Nutria]

rolling across the top of the atmosphere

Induced drag will cause unbalanced forces, which will eventually knock the cord out of station.

a momentarily stationary and easily predictable point for pickup

How in the world does a skyhook tip rotating at 9,000 mph become momentarily stationary?

so that planes can rendezvous

The first time that skyhook tip dropped below LEO, the drag would destroy the cable.

Re:"the free blah blah blah of space"

[werepants]

Being near the moon doesn't seem to me immediately better than any other place in orbit, and in many ways worse. If you want to mine regolith, just plant your colony on the surface. If you want to be close to Earth, LEO is closer and you get radiation protection from the magnetosphere. If you want to mine asteroids, go to where they are, or bring them to LEO. If you want something planet-like, Mars has more resources that are easier to use (ice, plenty of carbon readily accessible in the atmosphere).

I know people get excited about L1 and L2 and low-energy transfers, but that only works if you're willing to wait years to get to your destination - which isn't going to make sense for human spaceflight, at least until we can reliably solve the gravity and radiation issues, both of which are only solved long-term with lots of mass.

Re: "the free blah blah blah of space"

[DrPhiltill]

There's huge amounts of carbon in lunar ice, as shown by the LCROSS impact and the analysis of the debris cloud it threw up from a lunar ice deposit. This makes sense because the ice is apparently the residue of carbonaceous asteroids and comets, both of which are water-rich and carbon-rich.

Re:"the free blah blah blah of space"

[Immerman]

The point is, it's basically stationary with respect to the atmosphere, so even the bits extending down into the (extremely thin) upper atmosphere are moving at far, FAR below orbital speeds. Yes, there will still be some drag, but if it's seeing regular use the imbalances in masses being launched and returned are going to be a bigger issue than drag, and I already addressed that.

>How in the world does a skyhook tip rotating at 9,000 mph become momentarily stationary?
The same way the bottom of your tire becomes stationary while you're speeding down the highway. Pick a point on the tread and essentially it drops (almost) straight down out of the sky, stops, and then goes straight up again.

>The first time that skyhook tip dropped below LEO, the drag would destroy the cable.
Experiments in extending cables down into the atmosphere at orbital speeds say otherwise. And as I've explained this cable would NOT be subjected to anything like those speeds, more like a fast airplane at best, and almost entirely along its length. Plus, there's no reason to extend deep into the atmosphere, just far enough to link with a plane/rocket/airship in the extreme upper reaches. The idea is not to lift things up, but to hurl them sideways, which is ~95% of the energy required to get into orbit.

Re:"the free blah blah blah of space"

[Nutria]

The same way the bottom of your tire becomes stationary while you're speeding down the highway. Pick a point on the tread and essentially it drops (almost) straight down out of the sky, stops, and then goes straight up again.

There's a reason why calculus was originally called the study of infintesimals.

Experiments in extending cables down into the atmosphere at orbital speeds say otherwise.

What experiments?

more like a fast airplane at best

500 mph is going to keep you from falling back to Earth?

there's no reason to extend deep into the atmosphere

Sure there is, if you want the hook to reach a cargo airplane.

just far enough to link with a plane/rocket/airship in the extreme upper reaches

Show me an airplane that can lift 25 tons of cargo into the extreme upper reaches of the atmosphere.

Re:"the free blah blah blah of space"

[Immerman]

>There's a reason why calculus was originally called the study of infintesimals.
What does that have to with any
I believe NASA (or was it the ESA?) did some experiments a few years back, dropping cables like a mile into the atmosphere.

>500 mph is going to keep you from falling back to Earth?
No, being attached to something in orbit keeps you from falling out of the sky.

And you wouldn't be linking up with anything that currently exists, you'd design special aircraft/suborbital rockets for for the purpose.

Seriously, go read AC's wikipedia link on skyhooks, if you still want to discuss the issue, great, but I'm done wasting time trying to explain simple concepts to a contrarian.

Re:"the free blah blah blah of space"

[Nutria]

You can't hand-wave away engineering realities.

Re:"the free blah blah blah of space"

[Immerman]

So bring up some problems that actually exist and we can discuss them.

Re:"the free blah blah blah of space"

[Nutria]

bring up some problems that actually exist

I did, and you waved them away.

Re:"the free blah blah blah of space"

[RockDoctor]

the Moon is made out of Earth's crust, so primarily consists of the lighter materials.

More accurately the Moon is formed from the Earth's mantle. When the Giant Impact happened (which remains the most-likely formation scenario for the Moon), the Earth hadn't significantly differentiated it's SIALic crust ("granite" to a non-geologists approximation ; IAAG and can go into this in nuseating detail if you want) and SIMAic mantle. So what got thrown up was largely mantle material.

The main difference between Lunar and (bulk-) Earth compositions is that the Moon is considerably depleted in "volatile" elements : carbon, as you say, sodium and potassium (compared to calcium and magnesium), sulphur and phosphorus (compared to selenium and arsenic). This is also visible in, for example patterns of rare-earth elements, whose monotonous chemistry makes other differentiation processes hard. These are taken as fairly good evidence that much of the Moon passed through a stage in the vapour phase - presumably in the impact debris plume before a debris ring formed.

Re:"the free blah blah blah of space"

[RockDoctor]

The famous Bushveld complex is a concentration of platinum group metals thought to be caused by an asteroid impact melting into a magma body and then selectively crystallized out last as the magma body slowly cooled.

Strange then that the Bushveld's mineralogy matches very closely with multiple other cumulate deposits from Scotland to Norilsk to Greenland (thinking of ones whose thin sections I've examined myself), and the basement below the Bushveld doesn't sow the characteristic shattering of meteorite impact structures. (You could make a better case for Sudbury, but even that it is debated if much impactor material was left. For moderate impacts, essentially all of the impactor is blown out of the crater by the expansion of the vapourised impactor leading-edge and some vapourised planet bedrock. Most of the material comes down, but spread across between half and two hemispheres of the planet.

It is easy to underestimate how violent an asteroid impact is. When we next have one closer than Jupiter, people are going to have a real brown-trouser moment.

Re:"the free blah blah blah of space"

[RockDoctor]

Why are you hung up on reducing oxides to metals? Would that be the most efficient use of your resources.

You want materials with a high strength-to-weight ratio? Precisely why? Because you're used to designs that rely on high strength-to-weight materials? Is there a different way to achieve your production aim?

Re:"the free blah blah blah of space"

[RockDoctor]

[OP here.] Agree on pretty much all points.

Re:"the free blah blah blah of space"

[RockDoctor]

I know people get excited about L1 and L2 and low-energy transfers,

Yes, but not for the reason you're looking at.

Say you're on Earth and you hear that a robotic tug bringing a 500m diameter lump of asteroid belt to LEO has malfunctioned, and will be 500km off from it's target location/ time/ velocity heptuple. And that 500km error will plant it into an ocean that borders your home. you are advised to take your suicide pill sometime in the remaining month before your death.

Miss your target by $DISTANCE$ when aiming for one of the L-points and more likely than not the worst outcome would be a fine from the Parking Warden.

which isn't going to make sense for human spaceflight,

The papers are not about performing human spaceflight. They're about building the space-based infrastructure that would allow human space flight at a negligible cost, while simultaneously building power stations for Earth, possibly compute-stations for Earth. Maybe sun-shields at L1 to take 1-2% off solar irradience and maybe save the Arctic from melting. Human space flight (e.g. a geological exploration mission to Mars or Io) is way down the list of priorities.

at least until we can reliably solve the gravity and radiation issues, both of which are only solved long-term with lots of mass.

There is a physically-possible plan for solving either plan that doesn't involve large amounts of mass? Enlighten me!

Re: "the free blah blah blah of space"

[RockDoctor]

Oh hi Dr Phil. Worth the effort of visiting?

Re:"the free blah blah blah of space"

[RockDoctor]

The launching part is relatively easy, as you can tune the operating parameters so that the wheel is essentially rolling across the top of the atmosphere, presenting a momentarily stationary and easily predictable point for pickup,

In contra-point, 50 years ago the first spy satellites dropped canisters of film (remember - silver halides on plastic sheet) and they were successfully caught in mid-air from $SOME BOMBER$.

It sounds like rocket science, but it's well-established rocket science.

Re:"the free blah blah blah of space"

[RockDoctor]

I *will* talk about space elevators, having taught a class about them last year.

Feel free to plug more.

Is it an in-class or on-line course? Will it be available again?

Re:"the free blah blah blah of space"

[Immerman]

I gave you brief answers. If you want more, either read the literature, or ask more politely. This is a well established concept far more practical than beanstalks, accept that you're brilliance is unlikely to shred the work of the many scientists and engineers who have contributed to the concept.

For starters, ignore the atmosphere, there's no reason the skyhook can't reside completely above it.

Re:"the free blah blah blah of space"

[Immerman]

You reminded me of a line, from whence I recall not:

It's not rocket science.... Okay, it *is* rocket science, but it's not *hard*!

Re:"the free blah blah blah of space"

[Nutria]

there's no reason the skyhook can't reside completely above it.

Even the Hubble Telescope is exposed to some atmospheric drag, so the skyhook will need to be well above 335 miles.

1,240 miles is the distance I've read which is "completely above" the atmosphere, which is five times the altitude of the ISS.

Re:"the free blah blah blah of space"

[Immerman]

Yes, but even in LEO atmospheric drag is relatively negligible at orbital speeds - you'll get some very slow orbital decay that needs to be compensated for, but negligible heating or other direct evidence of drag.

Meanwhile a skyhook designs are typically thousands of miles long, so its center of mass and upper extents are essentially free of even the thin hints of atmosphere, and everything below that is counter-rotating, so that by the time the tip gets as low as the ISS, it's far, far below orbital speeds, almost stationary with respect to the atmosphere, so that drag is radically less pronounced - keep in mind that drag scales with the square of relative speed. And presumably the tether would be designed with drag in mind sd well, presenting the minimum possible cross-section in the plane of rotation.

Still probably not something that would make sense while we're were sending up only a few launches a month, but it becomes increasingly attractive as we establish a more meaningful presence in space and launch frequency increases. Especially if we're returning ores,etc. to Earth so that we can harvest momentum from them on their way down.

Re:"the free blah blah blah of space"

[Nutria]

you'll get some very slow orbital decay that needs to be compensated for

But you said it would go above all atmosphere.

Re:"the free blah blah blah of space"

[werepants]

The papers are not about performing human spaceflight. They're about building the space-based infrastructure that would allow human space flight at a negligible cost, while simultaneously building power stations for Earth, possibly compute-stations for Earth.

I would contend that most of that infrastructure has a better place to be than lunar orbit. For solar power - GEO is going to make the most sense for transmitting power to the ground, if it's providing power to somewhere in space, then co-locate it with whatever you care about. For harvesting asteroids - the equipment will be much lighter and more portable than the asteroids, so move the equipment to the asteroid's existing orbit. Earth mining operations process as much material as possible on-site, for the exact same reasons. You don't want to spend money transporting stuff that you're going to discard. For anything human related, you want to be in LEO (and protected by the magnetosphere) unless you have something specific to do, and then go where the job is.

So the point is that lunar orbit, L1, L2 might be attractive as pit stops, but there's little to recommend those locations other than being on the way to somewhere you care about. Getting there is a lot more expensive and less protected than LEO, less useful to Earth than GEO, and if you want resources just move the operation to the asteroid, don't move the asteroid and the mining equipment to an arbitrary third location.

There is a physically-possible plan for solving either plan that doesn't involve large amounts of mass? Enlighten me!

What I mean there is that you can solve either problem pretty cheaply in the short term - in terms of radiation, just choose to tolerate the risk, and/or bring a tiny shielded rad bunker that the astronauts can duck into in a pinch. For gravity, just accept the bone loss as the price of doing business, and/or have your astronauts do hours of exercise a day to try to mitigate the effects. Long term solutions are thick, heavy shielding (whether EM or just dumb mass) and a large centrifugal system.

Re:"the free blah blah blah of space"

[RockDoctor]

2 points (because it's been a long day and it's bedtime for me.

(1) At some point, there will be an astronomical body on a collision course with the Earth. If you like the idea of the planet you (or your descendants, should you choose to have any) being hit by a megatonne - equivalent event at random, without anyone doing anything about it, that's your choice. But I would think that the process of developing then necessary technologies in good time to deploy them if needed, is a fairly good investment. (As an aside, any and all of the credible techniques for terraforming Mars would require this technology. Terraforming Venus, not so much. But increasing the number of planets open to impact simply increases the likelihood of an impact, and therefore of the benefits of developing and practising moving asteroids.
I do agree with you on the comparative benefits of moving factories to materials versus materials to factories. But either needs reaction mass at your departure point, so at some point, someone is going to have to move that reaction mass to the departure point - near Earth. The seemingly dissimilar problems converge - move some (quite significant) masses of material into near-Earth space.

(2) in terms of radiation, just choose to tolerate the risk, and/or bring a tiny shielded rad bunkerLets look at some numbers. If you can fit a single astronaut into a sphere 1.5m in diameter without them going insane (note the "if" - as a caver (EN_US: spelunker], I'd find a week in a 1.5m chamber wearing. Your level of claustrophobia is likely to be different, but is unlikely to be lower than mine.), and you accept half the protection that the atmosphere gives, then you're talking on the order of (4/3)*pi*(R^3-r^3) cubic metres (for 'r' ~0.75 and R ~ 5.75m) of water ice, or an approximately similar mass of lead, concrete, steel, whatever. I make that a smidgin under 800 cubic metres of water ice, or 800 tonnes. If you do your shielding with steel (specific gravity ~7) then the volume reduction reduces that mass to more like 80 tonnes. In comparison with the estimate of the mass of the "starter kit" of between 12 and 40 tonnes ... well that's clearly an option that needs much more detailed analysis. Which is precisely what Dr Metzger's paper is about. (Just to point out something important - water ice can be re-used for either drinking or reaction mass with a heater ; to re-use steel similarly would require rather more tooling. You can even drink water ice, shit it out into a bag and put it back outside the ship and use it as radiation shielding.)

Re:"the free blah blah blah of space"

[werepants]

But I would think that the process of developing then necessary technologies in good time to deploy them if needed, is a fairly good investment.

I agree, but I think that can be a separate effort - making infrastructure projects more difficult/expensive than they have to be just to learn some things about asteroid relocation is going to be a worse solution IMO than making them distinct efforts - efficient asteroid mining, and efficient asteroid redirection.

Lets look at some numbers. If you can fit a single astronaut into a sphere 1.5m in diameter without them going insane (note the "if" - as a caver (EN_US: spelunker], I'd find a week in a 1.5m chamber wearing.

What I envision is something like an emergency bunker that is just large enough to fit the whole crew, and surrounded by some combination of fuel tanks, water supply, waste, and other massive materials that you'll be bringing with you anyway. This can provide pretty adequate shielding without much extra mass, but as you point out, it's going to be cramped. For that reason I would classify this as a short-term solution that is tolerable for exploration missions (and much better than the Apollo crews had) but not for sustained habitation. That's why I contend that we need orbiting manned facilities to be in LEO until we can afford the mass to shield large portions of a station. Which won't really happen IMO until we are mining asteroids.

Re:"the free blah blah blah of space"

[RockDoctor]

Which won't really happen IMO until we are mining asteroids.

for which we're likely to need robots on the Moon to extract rocket fuel from the polar regolith, for which we'll need large acreages (well, hectares or square kilometres) of solar cells at several locations (to keep the power on through the local night at some of the power stations) and the cables to link power stations to processing plant (1km of 30A cable with 250VAC insulation would weigh around 1/4 tonnes, mostly copper ; this is not trivial).

In short, you need that supply chain. Or you need to hump every kilo of that material from Earth to your first industrial site and then build your supply chain.

Re:"the free blah blah blah of space"

[werepants]

...we're likely to need robots on the Moon to extract rocket fuel from the polar regolith

There are any number of places to get rocket fuel in the solar system: water from comets, or the polar regions of the Moon or Mars, or just go straight to Mars and synthesize CO and O2 straight from the Martian atmosphere using nuclear reactors. Which place ends up being most attractive is going to be highly dependent on the capabilities and needs of the launch industry - if everything converges around methane (which it's looking to do, at least based on SpaceX and Blue Origin's exploration-class vehicles) then that works nicely with Mars, assuming you bring some hydrogen with you at first and then move on towards getting it from the poles or the rumored subsurface supplies. The moon is one good option, but it's not by any means a given that we'll have to go there first.

In short, you need that supply chain. Or you need to hump every kilo of that material from Earth to your first industrial site and then build your supply chain.

I agree with this. Once we get serious about space, the absolute top priority will be building up that supply infrastructure - and if we can make LEO cheap and routine, I think that will happen pretty fast.

Re:Another portion of utter crap

[K. S. Kyosuke]

Unfortunately, the "up" direction, i.e., away from Earth's center, coincides with the "into space" direction.

netcadd

[neset.16]

http://netcadd.blogspot.com/20...

Why is this easier in space than on Earth?

[superposed]

About half of the Earth's land is virtually uninhabited, which means nearly free land; and most of that land has good access to "free" energy (wind and solar power). So why would we have to go to the moon to setup an exponentially growing robot-run supply-chain? Is it ethically better to make rocket fuel and metals on the moon than in Antarctica or the Sahara Desert or northern Canada?

Re:Why is this easier in space than on Earth?

[superposed]

Funny, I read that as "somewhere where the environment can't reach you," which would be a fair critique of a robot supply chain on Earth. It's probably easier for robots to setup and maintain solar panels on the moon than to setup wind and solar arrays on earth, where they have to worry about wind loads, mud, corrosion, baby deer running into them, etc. But I don't know if that counterbalances the difficulty of getting started on the moon.

I left ethics as a leading question, because I think it's actually an interesting one. We tend to worry when people start messing up places where there's life or where people might see the view. Can we ignore those concerns in the Sahara Desert? On the moon? In the asteroid belt?

Re:Why is this easier in space than on Earth?

[DanielRavenNest]

It's not. That's why we are building the first self-bootstrapping automated factories here on Earth:

https://en.wikibooks.org/wiki/...

Once we have enough factories that have grown to full capacity, we tell them to build rocket factories and launch pads, and send new seed factories into space:

https://en.wikibooks.org/wiki/...

Re:Why is this easier in space than on Earth?

[TapeCutter]

Modern mines here in Oz are pretty much run by robots already, eg: the giant open cut Argyle diamond mine is operated by just 12 people (up to the point where the raw diamonds are ready to be assessed by a jeweler's eye).We do some really dumb shit too, eg: we mine bauxite in the NT desert, put it on a boat and send it several thousand miles south to Victoria where the state government gave them a great deal on a coal fired generator to run their electric arc smelter. The aluminium is then loaded on a boat that sails back past the mine to the northern hemisphere markets.

Why don't they smelt it on site using solar power from the desert around the mine? - Because "jobs for victorians".

Re:Why is this easier in space than on Earth?

[Applehu Akbar]

" we mine bauxite in the NT desert, put it on a boat and send it several thousand miles south to Victoria"

You used to send it to a fjord in New Zealand, where copious rainfall provided even cheaper electricity (the Manapouri project) to refine it. The Kiwis have now gained the ability to connect the isolated power project to the national grid.

Re:Why is this easier in space than on Earth?

[Applehu Akbar]

Haha, but environmentalists have already voiced the concern they will levy against extra-terrestrial factories and settlements: It will spoil the natural desolation.

Which is one good reason for manufacturing in space - the Greens can't reach it, because getting there involves technology they will not use.

Re:Why is this easier in space than on Earth?

[quantaman]

You probably have to start somewhere where the environmentalists can't reach you, and where no cute little deer baby dies because of your gruesome actions to further human civilisation. Also building a road in africa is far less exciting than GOING TO SPACE.

They already have mines up north, if building robot factories in Nunavut or the Sahara was economically viable I'm sure they'd find a way to make it environmentally acceptable.

But they don't even have the factories to build that mining machinery in Nunavut, it's all built down south and shipped up there. And even then the factories are typically close to population centres, rather than being in the middle of nowhere.

The constraint for factory development isn't land and environmental regulations, it's resources. Skilled labour, manufacturing supplies, shipping routes, markets, and supportive governments.

Manufacturing on the moon will not be cheaper than manufacturing in space, at least not till we've had massive technological advancement.

Now the question is whether it's cheaper to manufacture on earth and ship to the moon, or to manufacture on the moon.

The trouble with moon factories is all the inputs they require, even once you've built a computer factory a single computer requires a lot more inputs than the weight of a single computer, and then there's all the specialized components needed to keep your factory going.

It may be that we can use things like 3D printing to make do with a drastically smaller supply chain, but I suspect it's will be lot cheaper to build what we need on earth and ship it up.

Re:Why is this easier in space than on Earth?

[Anonymous Coward]

aluminium smelting is one of the most power intensive processes there is, expending 10-15 kilowatt hours for every kilogram of aluminium smelted. A solar plant that would partially cover that power cost even in the desert would be a gigantic undertaking in the billions of dollars and still be insufficient to cover normal operating hours for the plant.

Re:Why is this easier in space than on Earth?

[careysub]

It's not. That's why we are building the first self-bootstrapping automated factories here on Earth

We are? When is the first self-bootstrapping automated factory going to be completed? Where is it? Who is funding it?

All you linked to are a few web pages you wrote yourself, which simply describe your very, very high level concept for a program to do this with, despite the numerous bullet points, no actual details, just concept verbiage.

Building an actual self-bootstrapping automated factory on Earth is absolutely essential before we can start talking about putting on the moon - for reasons that should be obvious to anyone. Until such a thing exists this is just fiction. As far as I can tell, at the moment all plans for building a self-bootstrapping automated factory on Earth, much less the actual operating factory, are fiction also.

There is less to this "self-bootstrapping automated factory" you allude to than even the Mars One fake project (which at least has a staff and collects real money).

Re:Why is this easier in space than on Earth?

[K. S. Kyosuke]

It wouldn't cost "exponentially more" (what variable is in your exponent?), and one of the reasons why shipping is so cheap nowadays is that it uses absolutely shitty fuel that nobody else is allowed to use. If environmental regulations strengthen in the future (they already do near European coasts, if I recall correctly), say good bye to ultra-cheap transport. Pure solar operation is unlikely but some kind of hybrid operation seems plausible.

Re:Why is this easier in space than on Earth?

[K. S. Kyosuke]

I think the per-unit marginal costs are more interesting than the absolute costs, and it would appear that modern PV technology is actually headed into the realm of <<$1/W capacity and regular 30y-35y lifetime, at which point the marginal costs seem seriously competitive even assuming you still need to contract a power supplier for continuous operation throughout the night.

Re:Why is this easier in space than on Earth?

[K. S. Kyosuke]

And the space is not green so the Greens won't care about it.

Re:Why is this easier in space than on Earth?

[DanielRavenNest]

Also space is full of high levels of radiation, and it will scare them off. We only exist here on the Earth's surface because of the ozone layer, depth of our atmosphere, and magnetic field.

Re:Why is this easier in space than on Earth?

[DanielRavenNest]

> Until such a thing exists this is just fiction. As far as I can tell, at the moment all plans for building a self-bootstrapping automated factory on Earth, much less the actual operating factory, are fiction also.

Industrial automation is a thing, and has been for decades. We don't have to reinvent that part. What makes a seed factory different is the CAD/CAM files include making parts for more machines, besides the salable end products that any factory makes. Again, most of this has already been done, machine tool makers use their own machines that they made to produce more machine tools to sell to others. Robot makers use their own robots in their robot factories to make more robots. So our design problem is coming up with a growth path from a small and simple starter set (we presently have 8 elements in the starter set) to a complete factory capable of producing new starter sets.

And because people like you justifiably question the ability to do this, our project goal is to design and build prototypes to prove it can be done. We are not done yet, far from it. But you have to start somewhere, even if it takes 10 or 20 years to reach the goal. You will note that unlike Mars One (who I criticized myself, here on Slashdot) we don't give some fictional completion date. All we say is "here's the idea, here's what we've done so far, we are working on it".

Re: Why is this easier in space than on Earth?

[DrPhiltill]

The article that you're discussing already answers this. There's a section "5.3.2 Objection: Why Not Put the Self-Replicating Factories on Earth?"

Re:Why is this easier in space than on Earth?

[superposed]

Solar power is now cheaper than coal in good locations, and aluminum smelting is an interruptible process (smelters often buy interruptible power to get a better deal), so there's no need for any kind of backup. Solar power and aluminum smelting are a match made in heaven.

Re:Why is this easier in space than on Earth?

[vipw]

What have you done so far? Who is working on it? Who is funding it?

Who will control the resources?

[Anonymous Coward]

No matter what, government(s) will try to keep control. If nothing else, than to justify their own existence.

Re:Who will control the resources?

[DanielRavenNest]

They can try, but once people can make their own stuff using automation, they won't need jobs, and therefore won't pay income taxes. Governments can then pass all the laws they want, but without money they can't pay the Men With Guns to enforce them, and so become irrelevant. If they try to collect taxes/goods by force by coming to your door, it will become increasingly obvious they are just organized crime with paperwork. You can tell your computer driven machines to make weapons and then tell the government enforcers to get the hell out.

Re:Who will control the resources?

[TapeCutter]

# If nothing else, than to justify their own existence.
Justify? - politics is what occurs when two or more people communicate with each other, the hierarchical social structures found in all primate species is in our DNA, not our mind.

Re:Who will control the resources?

[lgw]

People are too used to a government, and the fact it hasn't been doing anything useful for quite some time now hasn't broken the habit. America is well on the way to being a totalitarian police state (we already have total electronic surveillance, and you can't read as fast a new law is made). If it weren't for civilian gun ownership, there wouldn't be a speedbump left to dictatorial control of all aspects of life. And many politicians seem to want to fix that gun thing.

Just go back to pillaging

[jfdavis668]

Before we maintained supply chains, we just pillaged what we needed.

Re:Eventually? Yes.

[K. S. Kyosuke]

This is the right answer.

Seed Factories

[DanielRavenNest]

I'm part of a project to build this kind of self-bootstrapping Seed Factories, for Earth first, then later in space. There's a report on applying the concept to space at:

* https://en.wikibooks.org/wiki/... (part 1)
* https://en.wikibooks.org/wiki/... (part 2)

I've corresponded with Metzger, and agree with his general idea, but disagree about placing the seed factory on the Lunar surface. The surface only gets sunlight half the time, while in high orbit you can get sunlight 100% of the time. The Moon is severely depleted in volatile compounds because it was baked for hundreds of millions of years, and is too low mass to hold on to easily vaporized materials. Near Earth Asteroids complement the Moon in terms of ore types, and the optimum place to bring everything together is a high orbit near, but not on, the Moon.

Re:Seed Factories

[careysub]

As I commented above, as far as I can tell - based on all the evidence you provide - this project you are part of is just you typing up web pages describing your project concept.

Let us know how much money this project currently is funded for, how many people are on its staff, and its timeline for building the first self-bootstrapping Seed Factory. Can you show us any actual equipment designs or prototypes, or tell us who is preparing same? Anything real?

Re:Seed Factories

[DanielRavenNest]

We currently have $95,000 of income producing assets and a 3 acre R&D location being developed. We are an *open source project*, not a venture capital startup, so we don't have paid staff, at least not yet. People contribute their time and funds to the project, and we do the best we can with it. Our workshop won't house all the machines and tools we need to build our prototypes. For that we rely on a network of makerspaces, individually owned equipment, university labs, etc.

We don't have a timeline for reaching a complete prototype factory, we haven't even finished conceptual design. For the moment the work is fleshing out the concepts, and renovating the workshop space on our property, so when we do have hardware to test, we will be able to. Things like solar furnaces need sunlight, which is why we have 3 acres. You can't test them indoors.

I'm a retired aerospace engineer. I devote my spare time to this project because it interests me. Other people's motivations are their own, I can't speak for them.

Re: Seed Factories

[DrPhiltill]

Valid points. I like the lunar surface for a number of reasons including the ability to put human crews on the Moon to do geology and get them to also help the industry get started. There's a lot of science that needs to be done on the Moon so we can leverage that. I do think asteroids play a crucial role in getting space industry started by providing propellant for cis-lunar operations (etc) and again at the end after space industry no longer needs material input from Earth because the resources are more abundant in the main belt, so asteroids are the real goal. IMO the Moon is important in the middle period. Solar duty cycle is like 70% near the poles so lunar industry will need to shut down 30% of each month until space based solar power has been constructed. Then it can power lunar activity 100% from Lagrange point halo orbits. There are additional ways to get 100% duty cycle for lunar polar industry. My final consideration is that either the Moon or asteroids is better than doing neither, and I'm glad we have companies working on both alternatives so we can discover what works best.

Re:Adam Selene says..

[BlueStrat]

"Loonies Threaten To Throw Rice!"

Ah, what a great read!

"The Moon Is A Harsh Mistress" - Robert A. Heinlein

Strat

Delicate balance

[ArtemaOne]

While not exactly the best research, the combination of two games has shown me how delicate the balance to achieve anything has to be. EVE Online has shown me the commerce and piracy side, however that required infinite lives in order to be made possible. Planetbase showed me how the building of a single structure out of a delicate balance, or not cultivating humanity in the proper training balance could cause a rapid collapse of the entire system. You have no natural air, water, food to fall back on. Anything goes wrong, any resource required to continue falls short, and the entire population dies in a rapid fashion.

Re:Delicate balance

[Immerman]

And that is the problem with games - they're designed to provide an entertaining challenge, not a realistic simulation. Even the most "realistic" games typically have only a passing resemblance to reality, for two main reasons:
1) Reality is *complicated*, way beyond our ability to simulate much beyond simple physics, especially on a PC.
2) Reality is *boring* - given any set of input conditions, people mostly muddle through somehow. Things may be touch and go sometimes, but smart people will rarely be brought low by anything short of catastrophic accidents or their own stupidity. Games though thrive on emotional stimulation - the blazing glory of victory, and the crushing tragedy of defeat. Storyteller's tools, not reality.

As one example, why would you run short of resources? Other than energy, you really only need more resources to grow, most everything else can be recycled indefinitely - just as we've been doing on Earth for the last few billion years. Biosphere 2 is a good example - its initial 2-year experiment went surprisingly well considering that it was the first time anything like it had been seriously attempted, and they had overlooked some major resource-sinks in their facility design (concrete absorbs a surprising amount of carbon and oxygen).

Re:Delicate balance

[ArtemaOne]

Of course there are reasons. Imagine your population is growing, so you need to do a new O2 facility. You need more plastics and metal to build it, because you just had to build a storage facility and a hydroponic lab. You lose a water facility to micro meteors, which takes out an existing O2 facility. Now you already needed more O2, and you have about 3 hours to produce a facility and components expected to take 18 hours, while short on resources. This means everyone dies.

Re:Delicate balance

[Immerman]

>This means everyone dies.

Or, you know, aside from the ridiculous timescales, you simply implement zero population growth - whatever it takes. Kill 2% of your population so that the rest survives. Or put 10% into an artificially induced deep sleep to reduce oxygen consumption until you can provide sufficient levels, like they did with the Apollo mission when the O2 scrubber died. In reality people muddle through.

Re:Delicate balance

[RockDoctor]

Of course there are reasons. Imagine your population is growing,

Didn't you read the bit in your contract of employment? The one that said "In the event of a pregnancy, the perons not carrying the foetus donates their air supply to the pregnant person (and foetus) and is escorted to the nearest airlock for a short walk outside. As per normal, your meat will then be taken down to the worm farm for recycling."

Re:Are Africans included in 'humankind'?

[TapeCutter]

Any explanation?

Your low IQ?

Recursive Manufacturing

[PJ6]

He's talking about recursive manufacturing, and honestly I'm surprised we haven't developed it already. Its power will utterly dominate our civilization's future, we have the tech to start development right now, and... we don't even have a Wikipedia page on it yet?

When we develop true RM, going to the Moon will be a footnote.

Re:Recursive Manufacturing

[Tony Isaac]

Automation is still hard, even for something as "simple" as an automated hamburger joint. You can easily enough automate specific tasks, such as filling drinks or cooking burgers. But automating EVERYTHING, from cleaning to repairs, is a lot harder. And then automating the manufacture of all of the machines needed to manufacture hamburgers, is another order of magnitude more difficult and complex. It's not at all surprising to me that we haven't done this yet.

Re:Recursive Manufacturing

[DanielRavenNest]

> we don't even have a Wikipedia page on it yet?

We have a WikiBook half written about it: https://en.wikibooks.org/wiki/...

There's a Wikipedia page on self replicating machines: https://en.wikipedia.org/wiki/...

But "fully automated self-replication" is both a limiting concept, and *hard*. There is no reason you can't make different machines than the ones you start with, or different sizes. So a "starter set" can be smaller and simpler than the final factory. All the complexity is in the stored computer files that tell it what to build. There is also no reason that it has to be 100% automated and make 100% of its own parts. Those are theoretical ideals like 100% efficiency. We can tolerate some manual labor and buying parts and materials from outside. The only real requirements are to be efficient enough to compete with conventional manufacturing, and have enough surplus production to pay for the things you can't make on your own.

Re:Recursive Manufacturing

[RockDoctor]

The process of making a burger is already highly automated. The problems you're talking about are mostly those of dealing with the meat. By which I mean the humans, not whatever goes between the bits of bread.

Re:Recursive Manufacturing

[david_thornley]

There's no real problem with automating burger production. Automatic cleaning isn't necessarily that hard. However, the machines will break down sometime, and currently by far the easiest way to fix them involves humans.

As far as recursive manufacturing goes, we've got it already, it's just that there's a lot of humans in the process. Since humans typically like to have meaningful work, and typically need to do such in order to function economically, this works pretty well. The role for automatic recursive manufacturing would be to build incredible amounts of stuff with limited human work required, but that's going to require a lot of land and resources, and those are going to be limiting factors. It will never be necessary for a planet that has a real industrial base.

The advantage is that, if we can drop robots and machinery on a planet or minor planet that can not only be self-sustaining but grow into a good industrial base, it's going to be a LOT cheaper to colonize said body: just drop the factory seeds, let them grow, then move the people in.

Complete bullshit at this time

[gweihir]

Somebody has played too many build-up strategy games. Not only can we now not do this on earth, doing it on an airless rock is at least an order of magnitude more complicated. Lets revisit the idea in 50 years or so.

Re:Complete bullshit at this time

[DanielRavenNest]

Sorry, but this is wrong-headed. We have to start working on it *now*, so that in 50 years we have the experience to build the space factories. It was 60 years from the Wright Flyer to the 747, but you can't skip all the steps in between.

Re:Complete bullshit at this time

[gweihir]

It is not "wrongheaded" at all. Blindly believing in technology is though. Realistically, we will _not_ have the tech for this for the next 100 years or so, so revisiting the idea in 50 years is about right. May still turn out to be far too early.

Re:Complete bullshit at this time

[RockDoctor]

We have to start working on it *now*, so that in 50 years we have the experience to build the space factories

[Glum] Which will be fuck-all use when we spot the incoming dinosaur-killer asteroid due to touch down in 53 years.

(By "dinosaur-killer", I mean the current dinosaurs currently sitting on a lamp post squawking at each other outside the house. Not their bigger, already fossilised cousins.)

Re:Complete bullshit at this time

[david_thornley]

Some things advance slowly. Some advance with frightening speed. With massive advances in robotics and AI going on, I wouldn't be surprised to have all the necessary technology in a couple of decades.

Nothing out there - except everything

[joe_frisch]

Why go into space? It is vastly expensive in time and resources. There is nothing out there - except for everything.

Re:Are Africans included in 'humankind'?

[burni2]

".. continue to leech off us."

Hello,

my dear african leecher friend!

So much of you is african and I will not start with your herritage reaching back about 50.000 yrs.

But I will start with your very computer you are using, with your very - coltanic - phone you are using, with your golden dental replacements or mariage ring.

Ohh you like - african - platin instead of gold and also an african diamond.

Ohh you like african coffee, and you burn african oil in your car.

Think again how much of you is african!

And who the leecher in the rhye really is.

The strongest!

[burni2]

The one with nukes, space guns and rail guns.

Not the same environment

[aepervius]

The moon has dust storm, space not so much. So solar cell which are fine rated for twenty years may not do so well on the moon surface. So that means you need to add dusters to your panoply of robot. And satellite are engineered to have a finite life : and we so then can decay them safely once they don't have enough propellant anymore. And then the "abundant" resource still have the problem they must be refined in low gravity, and then sent back (yeah the usual "use them to build more stuff in orbit" has no relevance. In the very end you want to send back stuff down earth because that is what bring money. And until we found a way to have human living long in space, then keep stuff up there and build thing bring nothing). So I doubt the plan has leg today (and I doubt it will have any leg in the life time of my descendant which will have more serious problem on the surface with AGW, water source, and possibly fuel).

Re:Not the same environment

[K. S. Kyosuke]

Dust presence on the moon can be ameliorated by sintering the untouched surface layers. Certainly, if your efforts are large enough to transform most of its surface, you should have means to do that. Orbital mirrors would probably do; they could go into power densities of hundreds of kilowatts per kilogram and the lunar surface, as I'm led to believe, has poor thermal conductivity.

Plus, he didn't even say anything about bringing things back to Earth. The $300B business alone was mostly about communication and remote sensing. There has been none economical activity in space so far that included reentry of physical goods, and there quite likely won't ever be one. Some people think energy import is feasible (logically), and I'd add computation as the fourth item to the mix. Given the limitations on how much power you need for large-scale computing, building a massive brain in space does seem like an easy way of circumventing the very quickly rising needs of our computational efforts (I believe the IEEE mentioned something like 10% of our total energy consumption? Not sure if that was just US or global, but if the developing world actually develops, it's going to be more like the US in the future than like itself on this day so it's won't matter in the long run - we know that the global economic inequality has been decreasing for the last thirty years or so) There's no certainty that we'll be able to progress significantly beyond the limits of current silicon, and if that unfortunately turns out to be the case, we'd have to "scale out" and available power would become our primary worry. You speak about environmental issues on Earth, and, well, here's a way of getting around a part of them, assuming that our computational needs don't shrink in the future, which I consider that unlikely. In the very long run (think thousands of years!), it may yet turn out that we have no other choice. But sure, none of us will be alive by then. In fact, we will have been dead for centuries.

Obviously, there's no reason at all to import any physical item, that's ridiculous, virtually everything is available on Earth in reasonable quantities for comfortable life.Unless you find some very rare but technologically interesting elements out there. For example, some people think that metallic asteroids could have large amount of siderophile elements in them. Specifically, large amounts of platinum could simplify large-scale roll-out of chemical processes (substituting today's choices) requiring platinum catalysts that are currently limited by their price. However, the case for this seems still quite weak to me. I'd need a lot of convincing to see how we can't overcome the limitations by using (cheaper) engineering ingenuity.

Re:Not the same environment

[K. S. Kyosuke]

Sorry, that should have read "10% of our total electricity consumption", quite obviously. 10% of total energy consumption would be mind-boggling.

Re:Not the same environment

[RockDoctor]

[SIGH] I post a link to the original papers, and then people don't read it. Sometimes I sympathise with "StartsWithABang".

Re:Not the same environment

[BarbaraHudson]

if the developing world actually develops, it's going to be more like the US in the future than like itself on this day so it's won't matter in the long run - we know that the global economic inequality has been decreasing for the last thirty years or so

It was expected that, with rising education and incomes, the African continent would see declining birth rates. It seemed to work at first, but with large parts of the continent stuck at 6 kids per family (the continental average is 4.5), poverty will increase.

The income level for poverty is set at $1.90/day. Using this stat, there are fewer people living in poverty, and yet real poverty is increasing

Someone living today at the new poverty line does not necessarily enjoy the same standard of living as someone at the old line did in the past, however. PPP figures do not measure the affordability of a specific bundle of goods from country to country. Every country experiences its own unique pattern of inflation, and so the new poverty line, translated into local currencies at the PPP rate, will be more than enough for a square meal in some countries, and much too low in others. Looking at national price indices rather than PPPs, half of the world’s population live in countries in which $1.90 buys you less now than $1.25 did back in 2005, according to a paper released this week by Sanjay Reddy of the New School for Social Research in New York.

So saying poverty is going down is misleading, even if it makes for feel-good stories.

Re:Not the same environment

[RockDoctor]

and I'd add computation as the fourth item to the mix.

Computation is expressly considered in one or other of the papers.

In the very long run (think thousands of years!), it may yet turn out that we have no other choice.

I think it's more of a thousands of weeks issue, not a thousands of years issue. It could happen within your lifetime. It's not even inconceivable within my lifetime, if I stop smoking.

pipe dream

[aepervius]

"The actual escape energy from Earth is 62.5 MJ/kg = 17.375 kWh/kg = $1/kg at wholesale electric rates, about what I pay for potatoes. We just have been terribly inefficient about how we get to space." that's the price of fossil fuel. Which don't cut it for launch in space. If you got an efficient process to go up in space at those price I am sure you can tell NASA, ESA, Elon musk and many other, they will be interested. Hint : there isn't any or we would be jumping on it.

Re:pipe dream

[DanielRavenNest]

Any aerospace engineer, but apparently no member of Congress, knows the right approach to get most of the cost reduction:

* Stop throwing away several kg of aerospace hardware @ ~$1000/kg every time you launch. *

There's roughly 160 MJ/kg of fuel energy in a good conventional rocket, which results in 1 kg of payload with 31 MJ of orbital energy, so around 20% energy efficiency at best, and often 10% in not so good designs. But propellant is *cheap*, around $1/kg. By far most of the cost is the hardware.

Outside of NASA, most of the new rocket development involves re-using the hardware. The Space Shuttle was intended to save money by reusing most of the hardware, but the program was poorly designed and run and didn't achieve cost savings. They did, however fly hardware multiple times.

I "humankind" even a word?

[quenda]

I suppose the old-fashioned "mankind" is now as politically incorrect as a blackboard?

Re:I "humankind" even a word?

[RockDoctor]

Maybe - maybe not. Is "blackboard" politically incorrect?

Re:I "humankind" even a word?

[quenda]

Blackboard? No, its just one of those things that come up in "political correctness gone mad" rants. The real reason that blackboards are now called chalkboards is because they are usually green :) (In the UK, "black" for people was(is?) considered somewhat politically incorrect.)

But "humankind" is not a familiar word around here. Is it a political neologism (hu-man plus man-kind), or just a regional dialect word? It's certainly a redundant prefix.
 

Re:good book

[careysub]

Like "Moon is a Harsh Mistress" it is fiction, written to entertain.

Re:Sure we can, but will we be allowed to?

[K. S. Kyosuke]

I think you misspelled "Cardassians"? Or was that a clever pun?

RITA: Reusable Interplanetary Transport Approach b

[lagunastarman]

Amongst so many other accomplishments, Dr. Max Hunter outlined Reusable supply chain concepts for earth-moon, earth-asteroid and earth-asteriod systems. If we are lucky, in the next 10-20 years do we may get this by cleverly mixing what SpaceX, ULA and SLS are doing. (Obviously, some methods are more cost effective than others.) Eric Berger just wrote an excellent article on the realities of SLS in ArsTechnia. We already know the successes of commercial crew, SpaceX, etc.

Humanity, as oppose to ...?

[eric_harris_76]

Martians? Thetans? Let's go with some part (or parts) of humanity. I bet that's what was meant.

Best to break the question up into smaller questions.

Will government? (NASA is asking the question, so that inclines one to believe that's the entire question. Especially before one RTF.) (The track record of Soviet Union and East Germany and ... suggests it's an unpromising approach.)

Will the private sector (not-for-profit)? Possibly, at least for their own expeditions. Do it well? Well enough to suit the people that provide the money.

Will the private sector (for-profit)? Possibly, but there has to be a reason to do it. One that suits the people that provide the money.

Watch this space. (Pun intended.)

Science education gone downhill

[dbIII]

Disappointing as fuck - could you at least look up what reduction of oxides means before blathering about nukes.
It's chemistry not just heat.

Space Merchants!

[tmjva]

I remember playing this silly DOS game for hours, moving my cargo from one star to another. (Or was it Apple ][?)