Gravity Balloons

[AlanSE]

This is so cool! Amazing illustration.

You went a bit of a different route than I had in mind. I think it's worth looking at, where you start with a liner, inflate it, and then add rocks around it while you add air.

Initially, its pressure doesn't need to be much of anything. But once you start adding the rocks to it, the strength of the balloon will limit how large the rocks can be without causing an avalanche of rocks which will destroy the entire construction.

I could also see this method being practical for near-term space gas and propellant depots. Since these can be stored at lower pressures, you could build containers like this using asteroid rock that comes from smaller Near Earth Asteroids. Since the requirements on the balloon material are light, you could lift it from Earth in ordinary launch vehicles, but still store immense amounts of gas.

[stevebowers]

Thanks! Good idea. I'll add a note to that effect.

[stevebowers]

Amended.
http://www.orionsarm.com/eg-article/54a180bebfacc

[sandcastles]

I did a search for "negative mass" on this site and didn't find anything. Maybe you're calling it something else?"
Would it be worthwhile filling a balloon with negative mass?

[stevebowers]

We call negative mass exotic energy or more technically averaged null energy condition (ANEC)-violating negative energy, sometimes known as phantom energy. Because of the mass-energy equivalence principle, negative energy of this kind is equivalent to mass, and probably you couldn't actually have baryonic matter with negative mass as such since it would fly apart.

A balloon inflated with negative energy is an intriguing concept; after all wormholes are inflated with negative energy, so it should be possible. An interesting possibility is a matter balloon with a wormhole at its centre - this is an idea I came up with for my novel Betrayals, and which occurs in a quite different form in Iain Bank's The Algebraist. But (ANEC)-violating negative energy is a very tricky thing to make, something that only transapients and above can produce- so I wouldn't expect there to be many negative-energy balloons in the Terragen sphere.