3. Wet Star Nemo
The previous blog described a Wet Star as an enhanced Steppenwolf. This is a simple form; but perhaps more advanced models exist.
So consider Nemo, a Wet Star. It has no iron core; it is almost entirely liquid, and heated by artificial fusion. It incorporates megastructures, and also a swarm of deep-ocean ship-arcologies. Its water radius is 1578 km; its ocean (well-mixed by convection) averages 30 degrees C; pressure at the core is 1.04 gigapascals; it has about 1/3 the mass of Europa, 1/24 gee surface gravity (and zero-gee at the core!), and an escape velocity of 1179 m/s.
Nemo’s ocean convects in a double-donut, with warm water rising to the poles, flowing to the equator, cooling and sinking there. Therefore open ocean at the poles and ice at the equator. But perhaps other convection patterns could prevail, such as single-donut convection; to avoid this, the Nemo ships will cooperate to manipulate heat generation and currents.
I have been assuming that a million fusion-powered ships holding a hundred billion people will generate enough waste heat to keep the wet star liquid and convecting. I have not done the numbers, and indeed have no idea how to do such numbers; so the basic idea of the Wet star may be entirely invalid. Will it freeze over? Will it boil? What is the correct power output per ship?
Nemo has a magnetosphere, generated by a superconducting loop spanning Nemo’s equator. This loop is housed in a megastructure; the Ring, a tunnel 1 km wide and 9914 km long, buried under the equatorial icebelt. The Ring contains the superconducting loop, dry dock for the ships, monorail, particle accelerator, servers for the planetary internet, other big equipment, parklands, towns, and cities. The Ring is a classic mega-habitat; if you populate it at New York City density (about 68380 people/km^2) then the Ring has about 678 million people. A proper nation! And just for the planetary port!
If you make the Ring ten km wide, then New York City density gets you 6.78 billion people; a properly Trantorian world-city! I recommend alternating cities, towns, and wilderness, for a billion people. The Ring as Port World!
The Ring is buried kilometers under the equatorial icebelt (for meteor protection) and has bits poking out; including at least one elevator cable to geosynch, for cheap planetary access to space. Also the exit ports for the particle beam, and maybe for the mass-drivers. (Though perhaps mass-drivers and elevator cables don’t mix.)
Nemo is accompanied by a small moon covered with with ion drives and microwave rectenna. Nemo’s Ring and ships beam microwave power to the tug, which powers its ion drive, which holds it at a fixed position near Nemo; a gravity tug. This, plus slingshotting past large planets, is Nemo’s motility system.
Nemo’s ocean and its Ring form two quite distinct technozones; Nemo’s yin and yang, so to speak. Most of the people of Nemo inhabit 1 km-wide diamond-hulled deep-ocean fusion-powered arcology ships. I wanted a million ships in Nemo, but I worried that this might crowd a water sphere merely 1578 km in radius. Not to worry; that’s a volume of 1.649 * 10^10 km^3 ; if that is divided among a million ships, that’s 1.649 * 10^4 km^3 per ship. I here assume that the average distance between ships is the cube root of that number - though perhaps I am off by a factor of the square root of three or something. If not, then there’s about 25.4 km distance between ships.
That’s not too crowded, I think... but I suppose that traffic control will be a constant necessity. You don’t want to crack your diamond hull. No doubt the ships will exhibit swarming behavior, like birds, or fish!
So let’s say a million ships fit into Nemo with reasonable comfort. I had originally wanted to put a million people in each ship, but on second thought 100,000 people is a perfectly fine city, and I think they will fit comfortably into a kilometer-wide sphere with room for equipment. A million ships times a hundred thousand people per ship is a hundred billion people.
100,000,000,000 people! That’s a flock of type I civilizations, all wired together! And in such a small volume, too!
And if you want a trillion people, then let each ship be 2.2 kilometers across; that’ll accommodate cities of a million each.