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Question Construction in orbit

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Catastrophe

Approaching asteroid? Is this THE one?
Feb 18, 2020
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Now that is an interesting extension of the Gaia hypothesis. I have not before seen it applied to the whole Solar System.

So let us extend the idea further to cover a Universe of galaxy people inhabiting this ultimate sentient being.

This is, of course, total unjustified imagination and anthropomorphic projection without any shred of evidence whatsoever, and I am not proposing it as the basis of a new cult system, especially one that demands absolute belief.

Cat :)
 
Apr 26, 2020
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Really big things must be built in outer space from materials that that are available without fighting the Earth's gravity well. The Moon appears to be the ideal place to source materials if the mining, processing and lunar launch infrastructure existed.
 

Catastrophe

Approaching asteroid? Is this THE one?
Feb 18, 2020
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"if the mining, processing and lunar launch infrastructure existed."

Errrrr . . . . . . . . . just a minor consideration, of course.

Cat :)

As an afterthought, how does all this mining, processing and lunar launch infrastructure get to the Moon in the first place?
 
Mar 5, 2020
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If you want to construct anything in space you start by having an encyclopedic knowledge of every construction technique man or animal has ever used.

If you already have Elon Musk’s Neuralink, it is only a 10 terabyte download 😊.

Then you put on a spacesuit, or program a robot to attempt these techniques.

A welder on Earth has taken years of practice to make it look easy. A robot might be better off using glue.

Physics in reduced g and vacuum conditions can allow techniques that would never work on Earth.

The Russian/Chinese lunar laboratory (probably operated by telepresence robots) can start finding out which techniques are useful and which are a dead end. You put in a 1000 hours of research and testing on Earth before you do an hour of robot testing on the Moon.

Our current space fabrication skills require too many man hours and too much dedicated equipment to be worthwhile. You can’t just keep pressurizing a habitat to find all the leaks (since all of that gas must come from Earth).

Learning how to build structures from sophisticated materials which can only come from Earth will disappear soon after we bootstrap production from asteroids or lunar material. Earth can supply people, complex organics (chocolate), sophisticated biologicals, and advanced technology like optics or electronics.

We could also stop going into Earth’s gravity well to retrieve tasty humans.
 
Mar 13, 2021
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Robotic exploration of Mars is important groundwork for future generations of human visitors to the red planet. However, humans have to prove that they can live and work on the Moon . There, they can develop the skills needed for humans to build a space faring system including a permanent lunar base. Mining the Moon for raw materials including ice at the poles for rocket fuel allows for the construction of rockets in lunar orbit to carry humans to Mars.

So, will space be a sanctuary for science and PR stunts or will it be a true frontier with scientists and pilots, but also miners, technicians, entrepreneurs, and settlers?
 

Catastrophe

Approaching asteroid? Is this THE one?
Feb 18, 2020
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"Mining the Moon for raw materials including ice at the poles for rocket fuel allows for the construction of rockets in lunar orbit to carry humans to Mars."

Many other posters seem to imply glibly that mining the Moon and other terrestrial bodies is a simple process.

I believe what really needs to be understood here is the tremendous effort in terms of transporting material to build the mines and provide energy necessary to operate them. You just don't build mines out of mud pies and operate them by playing pat-a-cake.

Cat :)
 
Mar 13, 2021
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"Mining the Moon for raw materials including ice at the poles for rocket fuel allows for the construction of rockets in lunar orbit to carry humans to Mars."

Many other posters seem to imply glibly that mining the Moon and other terrestrial bodies is a simple process.

I believe what really needs to be understood here is the tremendous effort in terms of transporting material to build the mines and provide energy necessary to operate them. You just don't build mines out of mud pies and operate them by playing pat-a-cake.

Cat :)
Sending robots to the moon to build permanent base/s there is not new(circa 1980's I was part of a project looking into this), what is new is 3D printing and self replicating mining/building robots, the tools needed to build a space faring system.

It takes 3 seconds for a radio signal traveling at the speed of light to go to the Moon and back. This makes the remote, telepresence operation of lunar robots from Earth feasible. Early steps in the location, surveying and harvesting of demonstration amounts of resources on the Moon by robots controlled from Earth. We do not have this luxury with asteroids.

Chuck
 
Mar 13, 2021
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Even with 3D printers you just don't build mines out of mud pies and operate them by playing pat-a-cake.
Not playing, historically survival and wealth creation are stronger drivers of exploration and settlement than curiosity. Traditionally, science(knowledge gathering) was a tool in the long process of exploration, which included surveys, mining, infrastructure creation and settlement(all advanced and protected with military assistance). This was the model of national exploration prior to the twentieth century.

What is needed is the incremental, cumulative build-up of space faring infrastructure that is both extensible and maintainable, a growing system whose aim is to transport us anywhere we want to go, for whatever reasons we can imagine, with whatever capabilities we may need.

Chuck
 
Dec 29, 2019
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Chicken vs egg problem. Or cart before horse.

As analogies go I think it may be more like sailing era exploration trade and colonisation but with oceans and distances too large to do direct travel; you need floating way stations to resupply the ships for them to make it there and back but building and keeping them supplied is hugely difficult and makes that trading uneconomic. And without the trading the colony is not viable. This despite - hypothetically - everything you need being in the water you float on, extravagantly abundant but inaccessible and unusable.
 
Nov 11, 2020
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I was just curious about how I work with large machines in wall work. I know you can build space stations in orbit, but are there really big spaceships built that can be assembled from parts in orbit? It would be really cool to say, build something like 2001's Discovery in orbit with multiple missions, and then fly into the solar system. Theoretically you could use Space Station Building Blocks to build something that looks like a ship, and then attach some sort of engine to it.
 
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Mar 13, 2021
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Chicken vs egg problem. Or cart before horse.

As analogies go I think it may be more like sailing era exploration trade and colonisation but with oceans and distances too large to do direct travel; you need floating way stations to resupply the ships for them to make it there and back but building and keeping them supplied is hugely difficult and makes that trading uneconomic. And without the trading the colony is not viable. This despite - hypothetically - everything you need being in the water you float on, extravagantly abundant but inaccessible and unusable.
The Lagrange point between the Earth and Moon is a convenient and practical location to store supplies for space faring. We need an incremental, cumulative program that could be paid for as we established these incremental capabilities. The Moon is a destination, but more importantly, it is an enabling asset. By using lunar resources, we would learn to "cut the cord" with Earth of space logistics.

Chuck
 
Dec 29, 2019
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The Lagrange point between the Earth and Moon is a convenient and practical location to store supplies for space faring. We need an incremental, cumulative program that could be paid for as we established these incremental capabilities. The Moon is a destination, but more importantly, it is an enabling asset. By using lunar resources, we would learn to "cut the cord" with Earth of space logistics.

Chuck
I am afraid my view of these things is inverted and cutting the tie with Earth doesn't feature at all. Rather than a problem to bypass, I think maximising the flow of trade to and from Earth is central to viability.

That umbilical cord needs to be a LOT bigger for a LONG time before enough growth can happen to risk cutting it. In-situ resource use, to make a project less costly and more viable requires that it actually cost less to do that than supply it from Earth. But the project itself needs a sound economic basis - requiring Earth for technology, investors and customers. I don't see how that can happen without physical trade in bulk commodities at reasonable cost. Lunar mining looking to a far future pay-off looks non-viable to me - no notable resources of high value there, no customer base besides Earth, no incremental build up possible, especially where a spaceport that can fuel and service rockets is required just to get started.

Is the Moon even the best option for obtaining space resources? I'm thinking the moons of Mars make at least as much sense; similar delta-v requirements to Earth's moon to get to and from Earth orbit or Earth itself but without that deep lunar gravity well. I expect better resources if they have the kinds of materials that asteroids have, ie nickel-iron as grains, chondrules and metallic masses, that have use and value with minimal processing. Water ought to be a component of carbonaceous material and carbonaceous material is itself a resource but nickel-iron has commercial value... if you can deliver it to Earth.

I suspect the tech advances required to make lunar resources viable will make Earth exports more viable - a paradox.
 
Mar 13, 2021
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I am afraid my view of these things is inverted and cutting the tie with Earth doesn't feature at all. Rather than a problem to bypass, I think maximising the flow of trade to and from Earth is central to viability.

That umbilical cord needs to be a LOT bigger for a LONG time before enough growth can happen to risk cutting it. In-situ resource use, to make a project less costly and more viable requires that it actually cost less to do that than supply it from Earth. But the project itself needs a sound economic basis - requiring Earth for technology, investors and customers. I don't see how that can happen without physical trade in bulk commodities at reasonable cost. Lunar mining looking to a far future pay-off looks non-viable to me - no notable resources of high value there, no customer base besides Earth, no incremental build up possible, especially where a spaceport that can fuel and service rockets is required just to get started.

Is the Moon even the best option for obtaining space resources? I'm thinking the moons of Mars make at least as much sense; similar delta-v requirements to Earth's moon to get to and from Earth orbit or Earth itself but without that deep lunar gravity well. I expect better resources if they have the kinds of materials that asteroids have, ie nickel-iron as grains, chondrules and metallic masses, that have use and value with minimal processing. Water ought to be a component of carbonaceous material and carbonaceous material is itself a resource but nickel-iron has commercial value... if you can deliver it to Earth.

I suspect the tech advances required to make lunar resources viable will make Earth exports more viable - a paradox.
The extremely weak surface gravity of an asteroid(like Mar's "moons") is almost microgravity and makes it very difficult to separate materials there without specialized equipment, again adding mass, power, complexity and cost to the processing chain.

Much of the "dirty work" of resource processing involves separating some substance from another, or extracting something embedded. Having gravity usually makes this an almost trivial step, one we do not think about very much - unless we do not have it. The Moon does indeed have a significant gravity well(1/6 that of Earth) which works in our favor when processing materials.

It takes roughly two tons of water-equivalent liquid hydrogen - liquid oxygen propellant to lift one ton of water from the Moon to the Lagrange point where it can be used to supply and fuel a variety of spacecraft. That same ton of water lifted from Earth would take over 10 tons of propellant to deliver it.

Chuck
 
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Apr 28, 2021
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Wouldn't it be better to build, things like space ships / stations, directly in orbit instead of building them on the ground and then putting them into orbit?
I would agree with this statement completely. And I suspect that in the near future that will be the case. Right now we are still extremely limited on launch capacity and working with a 20 year old space station.
One quasi example of this is already planned by SpaceX. In orbit refueling. True its not being built or assembled, but it will use multiple launches to create one usable craft for longer missions.
I could easily see us mining material from a Mars moon for use in building a rotating space station near the moon. Complex components would be shipped from Earth. Structural components, shielding material, etc could be gathered from the moon. We might even someday set up shop and build ships at the same location. But I agree with catastrophe, only refined materials would be shipped elsewhere. More likely they will be used for on-site construction.
 

Catastrophe

Approaching asteroid? Is this THE one?
Feb 18, 2020
2,440
1,451
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When all is said and done, the work to get the stuff up there is force x distance. That is thr weight times the height to which it must be lifted.
What is different is the efficiency of the force. Of course, J is correct in agreeing that the less contaminant (impurities in metal for example) is better. Better ship 100% metal than 10% metal and 90% contaminants.

Be careful about this:
"Wouldn't it be better to build, things like space ships / stations, directly in orbit instead of building them on the ground and then putting them into orbit?"
Of course it is true in a general sense. Where it falls down is where the "building in orbit" might involve large amounts of ancillary equipment. I have in mind large amounts of welding materials and chemicals in heavy gas cylinders - also the question of whether welding works in space.

Cat :)
 
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Feb 22, 2021
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When all is said and done, the work to get the stuff up there is force x distance. That is thr weight times the height to which it must be lifted.
What is different is the efficiency of the force. Of course, J is correct in agreeing that the less contaminant (impurities in metal for example) is better. Better ship 100% metal than 10% metal and 90% contaminants.

Be careful about this:
"Wouldn't it be better to build, things like space ships / stations, directly in orbit instead of building them on the ground and then putting them into orbit?"
Of course it is true in a general sense. Where it falls down is where the "building in orbit" might involve large amounts of ancillary equipment. I have in mind large amounts of welding materials and chemicals in heavy gas cylinders - also the question of whether welding works in space.

Cat :)
Attach a large module to the space station in which it will be possible to weld in weightlessness
 

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