The Starship Super heavy is a solid candidate for America's moon transportation system. But it's also so large it exceeds the floor space of many hereunto planned moon bases by itself. (that's TWO THOUSAND CUBIC METERS OF INTERNAL VOLUME!!) edit: make that 1100. With precision landing guidance it's easy to imagine a large moonbase consisting almost entirely of linked Starships.

It would be nice to send up a version of Starship with holes poked in it already, but the rigors of suborbital and then orbital flight on the way to the moon make that weigh too much. But once landed the stresses are greatly reduced and much less dynamic.

This device would have a self-contained apparatus to:
1. Magnetically lock itself to a slightly curved 1 cm thick steel plate, the hull of the Starship.
2. Form a pressure seal around itself on the outside of the hull.
3. Drill through the hull. making a sufficiently large hole to serve as an entrance/exit. Now this alone would greatly simplify constructing things using starship hulls on the moon. But I propose something that can do one more thing.
4. Maintaining the magnetic lock and pressure seal, inflate itself to whatever volume is deemed appropriate thereby expanding the internal volume of the Starship at any location or height that is desired.

I wouldn't be surprised if the Navy didn't already have something capable of doing this under much more strenuous conditions and enormously higher pressures for the purpose of shipboard hostile ingress, hostage rescue, and search and rescue.
-- Voice, Aug 16 2021

Diamagnetism https://en.wikipedi...g/wiki/Diamagnetism
Diamagnetic materials are repelled by a magnetic field [Voice, Aug 18 2021]

Spacex Starship https://en.wikipedi...iki/SpaceX_Starship
The starship upper stage has a volume of 1100 m^3 [Voice, Aug 20 2021]

Spin gravity calculator https://www.artific...ty.com/sw/SpinCalc/
[Voice, Aug 22 2021]

Vaguely related ... Low_20budget_20spacecraft
[normzone, May 30 2022]

Nice idea - using the fuel tank/fuselage of starships for moonbase construction.

Minor things

1) Magnetic lock: many stainless steels are non-magnetic

2) Most starships landing on the moon would be wanted for the return journey - even if only as an emergency lifeboat for long-term residents. You'd want to think really carefully before cutting holes in them
-- Frankx, Aug 17 2021


^ Hmm, a screw-nosed tunneling boring machine and several cases of that expanding foam product and/or flex seal to spray it its wake, make miles of tunnels under the rocky moonscape. Yeah. What am I forgetting?
-- whatrock, Aug 17 2021


Anything is magnetic if you're a strong enough magnet.
-- Voice, Aug 18 2021


You just know that they could totally cure starship blisters if they really wanted to. A vaccine maybe.

Oh... you meant actua... nevermind, as you were.
-- 2 fries shy of a happy meal, Aug 18 2021


I think there's some confusion, and rightly so, having read around. The "Super-heavy" component appears to be the 1st stage booster. You're not getting that to the moon. The second stage "Starship". Is a lot smaller, 800m3. Although that is still enormous by Apollo standards. Strangely the math adds up, the 3rd stage of Apollo ~130,000kg, similar. I wonder how the 2-3 stage system breaks down in terms of efficiency, and how much difference there is in thrust. Rocket tech isn't much different 1960's to now, but it has to be something, and skipping a stage helps simplicity. I even like the choice to go with steel. Steel is amazing. It will provide huge bonuses in terms ease of build, fatigue etc. The thermal conductivity is a boon also.
-- bs0u0155, Aug 20 2021


You're mistaken about the volume, [bs0] but so am I. linky

If Elon can get the numbers down to what he claims (10 million to launch in expendable mode, 1 million in reusable mode) we should be seeing everyday billionaires choosing to live in space. I figure the costs as this:

10 million: launch in expendable mode for the house
10 million: Launch in expendable mode for counterweight, cable, and other initial materials
5 million: outfitting the house, including artificial gravity design
1 million: other paperwork and planning
2 million: launches of fuel to orbit without reboosts
3 million: food, water, air, and supplies to live on

2 million/year: regular missions for maintenance on the house and additional supplies

total: 31 million plus 2 million/year

and decreasing per space house. A more expensive inclination would help with cancer risk and that commute is a doozy but if you've decided to live out your days of retirement IN SPAAAAAAAAACE then, if Elon's numbers are right, that is now possible for anyone with over a hundred million dollars.
-- Voice, Aug 20 2021


Since magnets won't work, use sticky tape and a welder.
-- scad mientist, Aug 21 2021


//we should be seeing everyday billionaires choosing to live in space. //

You'd atrophy to the point of not being able to come back.
-- bs0u0155, Aug 21 2021


[bs0u0155]; you say that like it's a bad thing...
-- neutrinos_shadow, Aug 22 2021


//You'd atrophy//

See the part about a counterweight, cable, and artificial gravity design. You may even be able to get it up to a full G. But I suspect for the more elderly folks being able to sleep in zero G and living otherwise at somewhat less than a full G may actually prolong their lives. It would be more comfortable resulting in more sleep of higher quality and symptoms of COPD would be relieved. Also for people with compromised immune systems isolation would be much easier. Also blood transport would be easier in reduced gravity, reducing stress on the circulatory system.
-- Voice, Aug 22 2021


Sleeping at 0g and living at 0g are two different things. Living on the moon would be enormously more difficult, expensive, and dangerous without any of that flexibility.

When I proposed sleeping at 0g I was imagining either a bedrooom resting at the 0g point on the tether or a sufficiently slow spin that having the bedroom at the Starship's nose practically constitutes sleeping at 0g

One advantage of a tether system is if your gravity doesn't suit you, you can speed up or slow down the spin at the expense of a little RCS fuel. You wouldn't want to do it every day but it's a nice customization...
-- Voice, Aug 22 2021


The upper stage is 50 meters long. If you put a counterweight right at the nose you'll need to spin it 4.4 rotations per minute to get 1G at the bottom. If you use a tethering cable your spin rate can be arbitrarily slow for the additional risk of space junk snapping your tether and sending you off into the wild blue at an unpredictable final orbit. Don't worry, it probably wouldn't actually de-orbit you. Healthy individuals may want the whole ship to be at 1g which would could be accomplished by significantly strengthening the whole structure, attaching a tether to either end, and spinning it "lengthwise" around a counterweight. At 30 feet diameter you'll feel a difference of .3Gish at most between "upper" and "lower" levels. This would, of course, require the floors to be designed lengthwise significantly reducing flexibility and increasing cost and launch weight.

At 30 feet in diameter (minus a foot or three for insulation, utility cables, and the like) each floor will be the size of a small house.
-- Voice, Aug 22 2021


//Your original idea was about building things on the moon out of used booster stages. Not sure where you’re going with this.//

It's not related to the original idea at all. Just a side thought.

//What flexibility?// The ability to choose your own gravity
-- Voice, Aug 23 2021


No, the stuff I wrote down occurred as a side thought to the original idea. Why are you trying to make this a deal?
-- Voice, Aug 23 2021


The fact that you said Moon transportation system made [a1] assume that the habitat would be moon-based rather than Earth orbital which would make simulating 1g difficult... but not impossible on a lunar colony.

Okay I hope that helps.

As you were.
-- 2 fries shy of a happy meal, Aug 23 2021


Actually pretty easy to make a circular lunar 1g structure. The tilt of the floor just needs to adjust to meet rotation for any given gravity requirement.
-- 2 fries shy of a happy meal, Aug 23 2021


Wanna experience 5 Earth gravity's? No problem. Just head down to level eighths ring.
-- 2 fries shy of a happy meal, Aug 23 2021


The idea is about the moon. The stuff about orbital retirement is completely different, unrelated, and having nothing to do with the idea except that they both involve Starships.
-- Voice, Aug 23 2021


True... we just don't thrive in micro-gravity is all and it needs to be addressed. I think... maybe, I don't know I just got here.

I would just like to go on record as stating that an orbital old age home sounds totally bitchin.
-- 2 fries shy of a happy meal, Aug 23 2021


//Because I usually come to HB looking for new ideas//

The idea I posted is not something I've seen, and believe me I've read a whole lot of science fiction. Talking about what's now financially possible due to Starship's finances -- In the comments! is certainly not presenting it as a new idea I invented and I think you're being not just uncharitable but rude to accuse me of that. And also I haven't seen a proposal to use it for retirement. I'll take my apology with extra groveling.
-- Voice, Aug 23 2021


After I've explained multiple times these are different ideas, you insist upon conflating the two. At this point I'm forced to conclude you're being disingenuous. And while it's true that parts of both ideas are discussed in fiction and have been done, none of that makes what I said -- any of it-- not worth posting. How about "really, genuinely rude", is that strong enough? no? Then I'll say this: I'm finished with this conversation.
-- Voice, Aug 23 2021


To revisit the above launch costs with current actual costs of $100 million in re-usable mode, $150 million in expendable mode, and with more realistic design costs: (so this would be the costs just for the first house)

150 million: Launch in expendable mode for the house
100 million: Launch in expendable mode for counterweight, cable, and other initial materials
30 million: outfitting the house, including artificial gravity design
5 million: other paperwork and planning
50 million: Bribing regulatory agencies and congress not to stand in the way of the launch
A 120 million dollar launch per year (a $100 million expendable launch plus the cost of materials to be brought up): food, water, air, and supplies to live on including fuel to reboost and maintenance

Total: $455 million plus $120 per year using current technology, value of a dollar, and launch costs. This is approximately in line with the initial costs of some of the most expensive houses in the world, but with that additional launch per year. Half of that would be Spacex profits.
-- Voice, May 30 2022



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