[bane]

I think the up-down space industry is not necessarily where the future lies. Fighting gravity wells is a huge and someday not terribly useful expense. Bootstrapping an end-to-end mine-to-manufacture space industry is probably where we'll be in the much longer term.

Right now we have to haul 100% of our mass into orbit. But what if we derived that mass from sources that weren't at the bottom of a huge gravity well? If we can shift most of that mass to those sources, convert the raw materials to finished goods and start to construct habitats in space, we can move that 100% up/down to just us and a few things we can't space-derive.

Building out that manufacturing and supply line is where the future really is and it will allow us to handle component assembly on scales far outside of the reach of any space-launch system no matter how cheap. Moving a million tons of steel and composite from one point in space to another is just a matter of delta-V to get it going and to get it to stop moving. Getting it up from the ground may be an impossible endeavor.

The entire ISS weighs only 450 tons. But an Aircraft Carrier weighs 100,000+ tons. Even with a 90% launch cost reduction, it's impossible to build Carrier-sized habitats without breaking national economies.

How does this get funded? Also not sure, but I have a sense that there's enough rich people who wouldn't mind living in orbit and dropping down to any point on the planet in about an hour if their physical presence is required and getting back "home" a couple hours later. But with enough industry, a contract signing ceremony to build a factory in France could simply be shifted to an intra-orbital flight to an orbital factory for a tiny fraction of that cost and time.

There's potential efficiencies in space. And a lot of very valuable R&D waiting to happen to make it work. And I think that R&D hill is where the medium-term money is.

[kowdermeister]

According to Musk, the goal is $1100/Kg. https://en.wikipedia.org/wiki/Falcon_Heavy#Launch_prices

The 100k ton carrier is possibly not needed up there, why would we need that? Let's build 10 ISS, that's 4500 tons, putting materials up there would cost $495.000.000, a minor project budget in military speak :) With 10 ISS material you could build a nice doughnut shape station we pictured in the 70's.

[bane]

Aircraft carriers, while we think of them as huge ships, aren't really all that large if you want to spend a lifetime on board one. Habitats have to be huge in order to not make the inhabitants bored out of their minds.

To put it into perspective, a 100,000 ton carrier houses around 5,000 people in tight quarters (the flight deck is just under 5 acres). and needs constant tending and provisioning for supplies. As an analogy to a space habitat they also make a kind of sense since they also have to house flying craft. There are only about a dozen carriers in the world at this size...or about a million tons.

Hollowed out asteroids with internal habitation spaces on the order of hundreds of internal cubic km would probably provide enough diversity to keep generations reasonably happy. The hollowing out process could supply raw material to space-based factories that would then build more habitat things and inter-habitat ships. Capture a couple comets and you have water, oxygen and other things. A small asteroid, something like 243 Ida has a total volume of over 25,000 km^3. Even if a couple km of shell were left, we're talking millions of tons of raw material.

[neolefty]

Nitpick: Can you actually hollow out an asteroid? It seems easier to use it to build an independently hollow structure.

Asteroids probably resemble piles of gravel -- maybe with ice mixed in -- more than chunks of stone or metal.

Update: Yes, this bugs me about The Expanse books. Spinning up Ceres to provide internal gravity ...

[TeMPOraL]

> Spinning up Ceres to provide internal gravity ...

Spinning a rock can be done over long periods of time. In The Expanse, it was a decades-long project, that earned the Tycho Corporation some serious engineering cred.

[lhopki01]

Spinning up asteroids can't be done. The speed you'd need for significant gravity would rip the asteroid apart.

[TeMPOraL]

[citation needed]

[imron]

> Nitpick: Can you actually hollow out an asteroid?

You'd probably need expertise in boring to pull it off ;-)

[bane]

It likely depends on the asteroid. They have very different compositions and densities.

[maxander]

Your 10-ISS-doughnut habitat would be a nice objet d'art, but what happens next? It can't pull more stations up after it.

Thinking for long-term space habitation requires projects that make human space presence self sustaining, at least in some sense or other. That's the point of space-based manufacturing and huge habitats; the more industrial power we have in space, the cheaper all future space missions become. At some point, they might become as cheap as terrestrial projects- then we'll have colonized space in a meaningful sense.

[gozur88]

>The entire ISS weighs only 450 tons. But an Aircraft Carrier weighs 100,000+ tons. Even with a 90% launch cost reduction, it's impossible to build Carrier-sized habitats without breaking national economies.

What makes space expensive is the one-off nature of the launches. If you really wanted to build an aircraft carrier in space you could take advantage of economies of scale not previously available. It wouldn't break a national economy. Not the US economy, anyway.

[ericd]

Nitpick, but your space station isn't going to have walls that are several inches of steel and several inches more of Kevlar composite, so for an equivalent size, it would be much much lighter. Agreed with your main point that we need to start manufacturing in space to get to very large scale habitats, though.

[lsd5you]

Solving the energy costs of launches (even including environmental impact) seems more tractable than solving manufacturing in space.