The ultimate in offshoring: How cheap would heavy-lift have to become that manufacturing in orbit becomes viable?

[AckSed]

We can do Lunar-refined, Earth-landed titanium a little smarter, but still simply.

Aluminium/oxygen rockets have disadvantages - the exhaust tends to clog up the combustion chamber and the temperature is really high - but it works well enough if you only plan to use them once, maybe twice. If it's too hot, feeding a little helium into the chamber both cools it and increases the specific impulse. (That last part may have to be gleaned as a byproduct from any fusion reactor or from helium-3 mining.)

Combine that with the news that NASA has been 3D-printing and firing aluminium nozzles, and we have a way to decelerate payloads. I know it's usually the hydrogen or methane that cools the nozzle, but oxygen cooling has been fired in a real engine (I can't recall the name, but it was a kerelox engine from a startup with a Russian engineer). If that doesn't work, a carbon graphite ablative liner is cheap and easily machinable.

The heatshield could be monolithic, foamed silica blocks or rings (foamed with what, you ask? Carbon dioxide) sawn out of a big block like polystyrene and sputtered with carbon if needed. In the dry, airless near-vacuum of Luna, this could be done in the open. The backing could be foamed, compressed titanium, which is strong and light and counts as part of the payload. In fact, make the entire inner surface out of foamed titanium, and have dual heatshields (one base, one cap) with a weight bias to sidestep the pesky problem of inverting in a supersonic airflow.

Deceleration? Lithobraking at terminal velocity should suffice, but if you want to recover them slightly easier aim into an artificial lagoon, with robotic barges to bring them in. The payload might also have to be titanium sponge to keep the density below water's.

It goes without saying that these will be monsters. They'll make StarShip's little skydive act seem quaint. I can't even imagine what a stream of hundreds of 150-ton Titanium Truckers (TM) will look like, and anything larger will make people very nervous.

[Mikki]

Manufacturing in orbit or on the moonsurface would not be that far away, but since huge amounts of taxmoney is spent on things like "Defense" there is not much left to accelerate new industries.

Humans could allready live on the moon for sure without all the "conflicts" around the globe mainly for fossil fuels and other ...ressources.

As the romans allready knew: "Divide and rule." 

[AckSed]

Oh yeah, if we're looking for an alternative foaming agent for heatshield silica, I just found out silicon carbide is used commercially to make foamed glass insulation. They get that from recycled and recovered solar panels. The SiC reacts with and reduces the molten silicon dioxide to make gas bubbles.

Wait. There's also a paper that says silicon carbide foams are possible if you change the proportions ("Fabrication of pure SiC ceramic foams using SiO2 as a foaming agent via high-temperature recrystallization", 2011). Instead of a little carbide, add up to 25% in weight of dioxide to the molten carbide. Result: lightweight ceramic foam with concrete-like compressive strength.

Silicon carbide can also be used to make telescope mirrors and is the basis of a lot of semiconductor technology. I know that silicon carbide inverters for solar panels are more efficient than previously. The moon might be the high-tech foundry of electronics in the future.

[JoeSchmuckatelli]

@Vanamonde this is the 'Next Unread'.  However when I next hit either 'Go to Topic Listing' at the bottom, or the Sci & Space tab at the top of the page, I will again get 'Error 500'.

[StrandedonEarth]

6 hours ago, AckSed said:

We can do Lunar-refined, Earth-landed titanium a little smarter, but still simply.

Aluminium/oxygen rockets have disadvantages - the exhaust tends to clog up the combustion chamber and the temperature is really high - but it works well enough if you only plan to use them once, maybe twice. If it's too hot, feeding a little helium into the chamber both cools it and increases the specific impulse. (That last part may have to be gleaned as a byproduct from any fusion reactor or from helium-3 mining.)

Combine that with the news that NASA has been 3D-printing and firing aluminium nozzles, and we have a way to decelerate payloads. I know it's usually the hydrogen or methane that cools the nozzle, but oxygen cooling has been fired in a real engine (I can't recall the name, but it was a kerelox engine from a startup with a Russian engineer). If that doesn't work, a carbon graphite ablative liner is cheap and easily machinable.

The heatshield could be monolithic, foamed silica blocks or rings (foamed with what, you ask? Carbon dioxide) sawn out of a big block like polystyrene and sputtered with carbon if needed. In the dry, airless near-vacuum of Luna, this could be done in the open. The backing could be foamed, compressed titanium, which is strong and light and counts as part of the payload. In fact, make the entire inner surface out of foamed titanium, and have dual heatshields (one base, one cap) with a weight bias to sidestep the pesky problem of inverting in a supersonic airflow.

Deceleration? Lithobraking at terminal velocity should suffice, but if you want to recover them slightly easier aim into an artificial lagoon, with robotic barges to bring them in. The payload might also have to be titanium sponge to keep the density below water's.

It goes without saying that these will be monsters. They'll make StarShip's little skydive act seem quaint. I can't even imagine what a stream of hundreds of 150-ton Titanium Truckers (TM) will look like, and anything larger will make people very nervous.

Well, my more serious concept  instead of slamming metal slugs into the desert, was to form the payload into a lifting body with a minimal control package. The outer layers ablate or vaporize away and the payload does a belly landing in the desert or catch pond. Scoring based on how many cartwheels the payload does after touchdown.

[kerbiloid]

As the heaviest possible planes are of ~500 t mass, and aren't designed for aerobraking (actually, even for fast turns), and the aerobraking is significant only for the bodies with low average density (space vessels and even warheads are lighter-or-equal than water), the titanium-class vessels can't be too heavy.
Tonnes, maybe tens of tonnes.
This means thousands of winged or shielded slugs per year.

[darthgently]

5 hours ago, kerbiloid said:

As the heaviest possible planes are of ~500 t mass, and aren't designed for aerobraking (actually, even for fast turns), and the aerobraking is significant only for the bodies with low average density (space vessels and even warheads are lighter-or-equal than water), the titanium-class vessels can't be too heavy.
Tonnes, maybe tens of tonnes.
This means thousands of winged or shielded slugs per year.

If we can do thousands of chugging container ships on the oceans we can also do thousands of winged slugs powered entirely by the magical power of gravity. It is a heavenly vision.  They should be foam cast in the shape of winged pigs

Edited November 7, 2023 by darthgently

[StrandedonEarth]

2 hours ago, darthgently said:

They should be foam cast in the shape of winged pigs

We’ll need shelter from pigs on the wing….

[sevenperforce]

On 11/5/2023 at 1:06 AM, kerbiloid said:

To let it make sense, the lunar production of Ti must be at least comparable to its production on the Earth, which is currently ~9.5 mln t of TiO₂ per year.
So, ~5.5 mln of Ti/year. I.e. 15 000 t / day.

As it's hard to deliver anda land 15 000 t/day softly, it should be thrown there, and then fall here.

This mean 15 000 t of white-hot metal daily passing through the Earth atmosphere per day.
It can solve the problem of the cities illumination, and will make the night sky very spectacular: the mesh of bright dots of tens of thousands of skylink and other LEO sats, crossed with a fiery comet rain of the falling titanium.

I wonder what capture/collection system you'd actually want to use for that.

Titanium's melting point is around 3000°F which is lower than typical cislunar-return re-entry heating, but let's suppose that the lunar manufacturing was such that ablative losses were negligible.

What would the ideal collection system look like? Shoot the titanium slag on a trajectory such that it lands in specified desert target zones, then come in after the fact with a bulldozer and scoop up all the sand on the surface and filter out the chunks of metal?

[kerbiloid]

I would probably suggest a highly-eccentric elliptic ring of the TiO₂ dust, with such periapsis position, that the dust finishes aerobraking (as it's already TiO₂, it stays unchanged) exactly above the on-ground collection spot.

So, several countries have their own white-bright elliptic loops in the night sky, which makes it rather spectacular, and can gather the TiO₂ at the preferred location.

[AckSed]

This is a white-paper that's just come out. Preprint, so pinch of salt, but still! Highly relevant: Semiconductor Manufacturing in Low-Earth Orbit for Terrestrial Use

It asserts that gaining the ability to manufacture semiconductors and other crystalline materials (CMs) in LEO will remove barriers to "quick, high-yield semiconductor production."

They're talking about researching ways to take part of or all the whole production chain up there.

Quote

This report is specifically focused on what manufacturing verticals within the global semiconductor supply chain should be executed in LEO and sold as products for Earth use.

 

[Terwin]

On 11/6/2023 at 6:00 PM, StrandedonEarth said:

Well, my more serious concept  instead of slamming metal slugs into the desert, was to form the payload into a lifting body with a minimal control package. The outer layers ablate or vaporize away and the payload does a belly landing in the desert or catch pond. Scoring based on how many cartwheels the payload does after touchdown.

If you can seal those titanium foams, then you have a lot of internal vacuum for buoyancy, make the 'bubbles' large enough and the whole thing may not be dense enough to hit the ground until it has had some time to in-gass.

Think of large spherical 'clouds' that take an hour to finally land if not collected.  Very low density should also help with reduced reentry heating.

[magnemoe]

10 minutes ago, Terwin said:

If you can seal those titanium foams, then you have a lot of internal vacuum for buoyancy, make the 'bubbles' large enough and the whole thing may not be dense enough to hit the ground until it has had some time to in-gass.

Think of large spherical 'clouds' that take an hour to finally land if not collected.  Very low density should also help with reduced reentry heating.

Problem is that you are coming in from the moon, doing multiple passes to aerobrake and adjust trajectory and you are not simple anymore. 
 

[Terwin]

4 hours ago, magnemoe said:

Problem is that you are coming in from the moon, doing multiple passes to aerobrake and adjust trajectory and you are not simple anymore. 
 

If you have a titanium sphere with a density similar to a dirigible, then I do not see a need for multiple passes, as your entire reentry vessel is effectively a strong, rigid parachute with a fairly high melting point.

[darthgently]

24 minutes ago, Terwin said:

If you have a titanium sphere with a density similar to a dirigible, then I do not see a need for multiple passes, as your entire reentry vessel is effectively a strong, rigid parachute with a fairly high melting point.

As long as it doesn't catch fire.  Molten Ti reacts vigorously (burns) with oxygen present, much like magnesium.  But the idea is intriguing.

Edited November 14, 2023 by darthgently

[Superfluous J]

35 minutes ago, darthgently said:

Molten Ti reacts vigorously (burns) with oxygen present

This is fine.

[StrandedonEarth]

The semi-conductor industry is interested in the possibilties...

Semiconductor Manufacturing in Low-Earth Orbit for Terrestrial Use: Download the pdf from this site

[magnemoe]

14 hours ago, StrandedonEarth said:

The semi-conductor industry is interested in the possibilties...

Semiconductor Manufacturing in Low-Earth Orbit for Terrestrial Use: Download the pdf from this site

This, its the stuff you want to focus on.  Also we don't know as testing has been limited as its to expensive to use industrial so no point testing. Now you could probably grow crystals in an capsule chip manufacturing would require something to dwarf IIS even if only for very expensive niche chips. 

[kerbiloid]

Interesting fact: they tell about th necessary zero-g for semiconductor industry for decades, but this industry still keeps running without it.

Probably, the necessity is somewhat overestimated.

[AckSed]

Necessary for the US as a competitive edge over those dreadful, too-far-ahead Asians.

[Superfluous J]

1 hour ago, kerbiloid said:

Interesting fact: they tell about th necessary zero-g for semiconductor industry for decades, but this industry still keeps running without it.

Probably, the necessity is somewhat overestimated.

It's necessary like how a shovel is necessary to dig a hole.

Sure you can go without but it'd be better to use one. But if shovels cost $10 billion per hole I'll just keep using my hands TYVM.

[magnemoe]

50 minutes ago, Superfluous J said:

It's necessary like how a shovel is necessary to dig a hole.

Sure you can go without but it'd be better to use one. But if shovels cost $10 billion per hole I'll just keep using my hands TYVM.

Think an top of the line cpu production plant set you back $10 billions anyway   these things are expensive

[kerbiloid]

It just doesn't look like a hundred of tonnes per world could be a game changer, but probably it's much easier to produce a ten thousands on ground, just less high-endish. To compensate quality with quantity.

Till now, it worked.

[Superfluous J]

4 hours ago, magnemoe said:

Think an top of the line cpu production plant set you back $10 billions anyway   these things are expensive

While we're finally in the era where the most expensive part of filming Tom Cruise in space is paying Tom Cruise, I still think that $10bil cup factory would cost more up there.

[darthgently]

40 minutes ago, Superfluous J said:

While we're finally in the era where the most expensive part of filming Tom Cruise in space is paying Tom Cruise, I still think that $10bil cup factory would cost more up there.

This is a great encapsulation of the situation.