Building a celestial body

thread:

What to build from 3D-H ofcaurse ; 3dh is not a material but a method the only one that in architecture today fir the computer ,and make a direct link from projecting to manufactoring. But the reson the method shuld be chosen are, that all it requier is sheet material, that mean that if you want to build a structure, all you must look for, is sheet material of some kind , look up 3D-H or 3D Honeycomb --- not the ready made sheets of honeycomb cubes but the buildng method.

*Want* to build it out of wimmun. *Have* build it out of unobtanium.

Concrete won't work, not enough strength for a shell that will support a human.

Enough to drink.

Our Moon swings the Earth around a little circle, and there is a "three meter high" lump that follows the Moon around. Jupiter is massive enough that it swings the Sun around a point just outside the surface of the Sun. You'd have real difficulties keeping the shell in place.

Dyson sphere. Ringworld.

David A. Smith

I fear that's a question that only RebarGuy can answer.

I, however, specialize in terraforming, and think it would be far easier to just terraform Mars, or maybe even Venus or Europa than build a concrete sphere around Jupiter. As Pat inspired; if you have the knowledge to build a concrete shell, your knowledge would likely find it impractical.

Second reference to Dyson on the group in a month!

I installed a generator and Lee County came out and told me "No can do" so we put it in the garage. Which got me to thinking why not the A/C? Concrete block homes, my neighbors hear my AC more than I do. And the pool crap.

Wouldn't that depend on how thick the shell was?

I'm not worried about the shell staying in place. (See my other comment about gravitational centering.) I'm more concerned about stresses induced in the rigid structure of the shell.

I read Dyson's original article, I own all the Ringworld books, and I just finished reading Niven's "Playground of the Mind" collection. (I checked it out at the library specifically for the "Bigger than Worlds" article it contains.)

Dyson doesn't posit a rigid structure. His theory accepts any structure (or arrangement of structures) capable of capturing and harnessing all of the energy output of a star. Using it as a habitable surface poses difficulties in terms of gravity and retaining an atmosphere. (Though I once calculated that, given all the mass in our solar system, one could build a a shell around our sun with the density of the International Space Station, an inner radius of 1AU, and thickness of 2km. So it's not impossible to inhabit such a structure.)

Think for a minute. The shell has to support itself against 1g with a very tiny curvature, and it will have to support a point mass of a few hundred pounds. And do all this with 5000 psi maximum stress (or less). Not in this Universe.

It didn't make sense there either. Displace the centers of mass off center, and they *will not* recenter without work being applied. Gravitation is not a force.

Something this size is not rigid. Something the size of a building is not rigid. And you are right to worry about stresses. I think they are insurmountable with any matter.

Hard to build anything out of hydrogen ice.

David A. Smith

messagenews:hH%ri.60216$ snipped-for-privacy@newsfe10.phx...

Alright Michael! High-five!

Hi-5!

In both cases I seem to have made similar references to Dyson going steady with Mary Jane...

The merest of quibbles, I assure you.

It's about gravity. On the surface of the Earth, you DON'T accelerate. Instead, you find that a certain force is required from your feet to remain standing.

This is what we usually call weight. So the formulation of g can be put not as an acceleration of 9.8 meters per second per second, but rather as a ratio of force(weight) to mass i.e. 9.8 Newtons per kilogram.

This helps you remember you can move to places some of them near the poles where the weight due to a given mass is higher, 9.81 Newtons per kilogram or more.....

Brian Whatcott Altus OK

I guess I had best go vent that sucker.

Are you asking me out on a date?

Michael Mol wrote in news:1185947320.737905.306490@

57g2000hsv.googlegroups.com:

Well, firstly, the *surface* of your object would have to be around the altitude you specified. IOW, if you created the object, and then covered it with a layer of growing medium ("dirt") of x meters, the surface of the construct would be

110,000 km - x m from Jupiter's center of gravity.

If your Object is a ring rather than a sphere, you'd also have to have walls to hold in the atmosphere.

(((IIRC, in "Ringworld", LArry Niven (*IIRC*) had a rig that rotated and therefore held everything against the inside of the ring.)))

As for materials, isn't a Ni-Fe composite the most common material in the asteroids? If so, wouldn't that be the logical material of preference?

Certainly, one planet couldn't supply all of the material, at least not without basically destroying the planet. But it seems to me (jsut on gut feeling, tho', no calculations) that the asteroid belt might provide enough material.

I think that destroying Jupiter's moons for the thing is a horrible idea. Esp. if there is any life on Europa or whatever.

BTW, re: using cables slung from an orbiting body and penetrating a planet's atmosphere for energy prioduction, that idea has already been proposed in a science fiction story (might have been by Ben Bova, but I read it many years ago so can't recall).

A shell around a planet might be less practical than a ring. For one thing, a rign would be a smaller target for asteroids and comets. For another, it would allow thermal and other radiation to escape from Jupiter. ANd then, of coruse, there is the amount of material required for a shell, as opposed tothe amount required for a ring.

As for holes - well, if you have the tech to do a shell or even ring, you have to tech to repair the thing....

"Don" wrote in news: snipped-for-privacy@news3.newsguy.com:

Of ocurse, if you rigged them to give a big shock to the @$$holes, you'd no doubt get sued for violating their right to steal... =>:-[

Our A/C and pool equip is all also outside. I understand that the A/C needs a lot of ventilation, but it also seems that there has to be something bnetter than just leaving the equipment "naked" so to speak.

Of course, the real ballbuster is that I'd bet dollars to donuts that the county and/or "homeowners' @$$ociation" offal-icials ALSO would refuse any permits to build equipment shelters on th e"grounds' that they'd supposedly be ugly. Here, they make an issue out of it if you only want to plant a *small shrub* near the a/c/ unit, because nothing that is "next to" the house can be over 5' in height.

OTOH, all of this stuff *used* to go into an equipment "room/closet", or into a vented space that was part of the garage. But that prob. (1) costs more money and (2) takes a few extra sq ft away from what is supposedly the "living space" (which IIRC is what gets taxed in many areas).

Around here, the air and water heaters, and all circulation units, are in the attics. Dunno whetehr there is a good reason for that - it's just how everyplace is done. The A/C cooling fan units are outside. Which seems goofy because there is a heck of a lot of A/C piping first in the walls, and then, a couple feet exposed to the elements. Whcih seems to me like it'd cause problems in the walls, and lose a lot of efficiency due to both that, and the outdoor exposure.

OTOH, most of the stuff that gets done in the world strikes me as being goofy, so....