[Spaceships] SM+35 Toroid Station?

[Anthony]

I think you're running into flaws with how Spaceships handles radiation shielding, it's a fairly trivial problem on truly large scale habitats. Other than that, I would probably not even try to use Spaceships for this, because it's just really far away from the sort of thing Spaceships is designed for.

[DataPacRat]

Originally Posted by AlexanderHowl

Sorry, I tend to layer my habitat designs and went back to an old design that had fifty-five habitat shells, each with 1 km of thickness It ends up being a effective projected area of 2 million square kilometers.

Ah, now I get what you meant.

Hrm... it looks like Spaceships' "Open Spaces" don't really match up with this approach, as their rated acreage comes nowhere close to what you describe. So, presumably, all those spaces would be built as Habitats; a SM+27 Hab system with total life support would house 10 billion people, and cost $3 quadrillion. Which /could/ work...

... though I'm still hesitant to try this approach, given how many things can go wrong with actively-managed life-support systems in a single century, let alone a hundred-thousand centuries. I admit that I'm heading into territory Spaceships doesn't come close to touching with this requirement, but I think I'd need a bit more persuasion to abandon my current 'self-correcting ecosystems' approach.

Originally Posted by Anthony

I think you're running into flaws with how Spaceships handles radiation shielding, it's a fairly trivial problem on truly large scale habitats. Other than that, I would probably not even try to use Spaceships for this, because it's just really far away from the sort of thing Spaceships is designed for.

True, but where Spaceships /can/ stretch this far, it's offering some interesting insights, such as how viable any particular drive-system might be to nudge such a ridiculously-large body's orbit. (Eg, the rocket equation is less of an issue than flying enough fuel-mining robotic craft just to feed a SM+29 mass driver; the fuel for which costs $3 quadrillion to provide 0.00003 mps of delta-v to a SM+35 station. (Which is cheaper than any other non-superscience drive in the books, usually by orders of magnitude.))

[AlexanderHowl]

Unless you have some sort of active management system, a habitat would probably destabilize within a thousand years or so regardless of the size as artificial structures need repairs since they cannot depend on gravity to keep everything together. For example, even a relatively small asteroid impact (~10 m radius) would imbalance the spin gravity system by subtracting mass from somewhere, which would result in the entire system decaying within a few days without load shifting (0.2 rotations per minute is still a rotational velocity of more than 20 km/s). Since a 10 m radius S-type asteroid masses ~10,000 metric tons, it would hit with an average energy of ~400 kilotons of TNT, probably fragmenting off a few billion metric tons of stone armor.

[DataPacRat]

Originally Posted by AlexanderHowl

Unless you have some sort of active management system, a habitat would probably destabilize within a thousand years or so regardless of the size as artificial structures need repairs since they cannot depend on gravity to keep everything together. For example, even a relatively small asteroid impact (~10 m radius) would imbalance the spin gravity system by subtracting mass from somewhere, which would result in the entire system decaying within a few days without load shifting (0.2 rotations per minute is still a rotational velocity of more than 20 km/s). Since a 10 m radius S-type asteroid masses ~10,000 metric tons, it would hit with an average energy of ~400 kilotons of TNT, probably fragmenting off a few billion metric tons of stone armor.

I suspect that such external astronomical events would be the main reason to switch from passive management to active intervention. (Another such possible trouble could be a Carrington-level CME.) How far could a SM+31 Enhanced Sensor Array, with an Array Level of 32, pick up any such bodies? My notes on detecting a SM-10 piece of junk is that at 50,000 miles, the modifiers to the roll are -10 (SM), -46 (extreme range, 50,000 miles), +32 (telescopic vision), +10 (in plain sight), +24 (silhouetted against deep space), for a total of +10, automatic detection. A 10-metre rock is, what, SM+6 (SM+4 for dimension, +2 for sphere shape), meaning rolls to detect it are 16 higher than that; so it would be auto-detected at, what, 20 million miles out? (Even further, if the station takes extra time for a scan: 150 million miles, with the +5 bonus for a half-hour scan.) Even at orbital velocities, an AU and a half seems a good enough distance to launch a staged series of countermeasures. (Though I'm still poking around with numbers to figure out if any of the reaction engines would let a Gaea move far enough to avoid such a strike, after detection.)

[AlexanderHowl]

Reaction engines are completely unrealistic at the size. The waste heat alone would vaporize the engines because their volume to area ratios would be so high. You have a BDO that cannot maneuver any better than any other large asteroid.

[DataPacRat]

Originally Posted by AlexanderHowl

Reaction engines are completely unrealistic at the size. The waste heat alone would vaporize the engines because their volume to area ratios would be so high. You have a BDO that cannot maneuver any better than any other large asteroid.

So I've noticed. (A SM+29 Orion drive system would use up 1,500,000,000,000,000 tons of drive-units to provide a whopping 6.4 metres/second of delta-v. Which would be enough to move the station its own width in roughly 10.8 hours.)

Since Spaceships doesn't handle sails above SM+12, I'm currently looking into (ie, googling) an option for selectively altering the craft's albedo, to see if I can figure out how much of a change in impetus that might provide; and then I plan on reading up on magnetic fields, such as the ones around gas giants, for any other options.

And once I get my fill of figuring out how one BDO works... I get to start thinking about /lots/ of BDOs in various places. (I don't know if GURPS can handle any sort of description for a Kardashev >2 precursor society, but I'll be willing to give it a try.)

Put another way, I'm trying to use Spaceships more as a springboard and less as a straightjacket. :) )

[Anthony]

Originally Posted by DataPacRat

Put another way, I'm trying to use Spaceships more as a springboard and less as a straightjacket. :) )

I recommend not trying to do either one. Spaceships is designed for quick and dirty, not accuracy.

[DataPacRat]

Say, could I get some help with some damage numbers here?

For a SM+35 craft, I get dST/HP of 200M; with 12 systems of stone armour and 1 system of nanocomposite armour, with Pyramid 34's armour-volume rule-tweak, I get an average of dDR of 780k for fore, central, and aft. Does that look right?

And to figure out what sort of rock can actually dent the stuff (before the 23 HP/second Self-Healing kicks in)... assuming typical orbital velocities of 10 mps, and assuming an average roll on the formula on SSp61, it looks like I'd need a rock with at least 1200 dST, which would be SM+16... is that anywhere near right? (Even a 100 megaton nuke only averages 700,000 d-Damage, and a 3 PJ beam 21,000 (and even with a (10) armor divisor, it's facing dDR of 78k).)

Is there any reference for damage levels for solar events stronger than the "a few times a decade" flares mentioned in SS5p40?

[RyanW]

"He's heading for that large space station."
"That's no space station. It's a moon."

Sorry, I was looking up something to compare SM+35 to, saw that Mimas fell right into the correct mass, and couldn't help but make that joke.

[Rupert]

Originally Posted by AlexanderHowl

Unless you have some sort of active management system, a habitat would probably destabilize within a thousand years or so regardless of the size as artificial structures need repairs since they cannot depend on gravity to keep everything together. For example, even a relatively small asteroid impact (~10 m radius) would imbalance the spin gravity system by subtracting mass from somewhere, which would result in the entire system decaying within a few days without load shifting (0.2 rotations per minute is still a rotational velocity of more than 20 km/s).

The effective gravity was given as 0.2g, and the diameter 650km, so the rotational period is about 2530 seconds, or ~0.024 rpm. The rotational velocity of the rim would be about 800 m/s.