The O’Neill “Island Three” habitat is a gargantuan cylinder with hemispherical end caps, 32 kilometers (20 miles) long and 6.4 kilometers (four miles) in diameter, with a habitable surface area of 325 square kilometers (125½ square miles) or 32,500 hectares (80,310 acres) supporting a population in the tens of millions.
(In the Gundam canon, the population is generally given as three to ten million.) The cylinder is rotated on its long axis at ½ RPM (one revolution every two minutes) to simulate Terrestrial gravity for the people living inside. (½ RPM is not very impressive visually, so the apparent rate of rotation is exaggerated to about two RPM in the animation.)Orbiting with one end facing the sun, it’s divided lengthwise into six alternating “ground” and “sky” panels, so only half of the inner surface is actually available for habitation.
Three mirrors project outward at a 45° angle from the end facing away from the Sun and reflect sunlight through the translucent “sky” panels to the landscaped “ground” panels opposite them.
Because the end caps of the cylinders are domed, each of the “ground” panels has what, from an inhabitant’s point of view, appears to be a 3.2-kilometer (two-mile) high “mountain” at either end.The simulated “gravity” resulting from the rotation varies from one “G” at the base of the mountain to zero-G at the apex. The drop-off is linear—at the 1.6-kilometer (one-mile) level, midway (45°) up the mountainside, the pseudo-gravity is 50% (½ G). You can calculate the acceleration that produces this pseudo-gravity using the formula F=rω²/g, where F is the resulting acceleration, r is the distance from the central axis, ω is the angular velocity (a constant equal to 2π times the number of rotations per second) and g is the acceleration due to gravity experienced on Earth (9.80665 m/s² or 32.174 ft/s²).
This is equivalent to the more familiar F=mV²/r formula, only substituting V=rω.
(On 7 November 2002, Ian Woollard wrote me to correct my math regarding the drop-off rate.)
The mountains and the “valleys” between them are landscaped to an idyllic green splendor, supporting six densely populated urban and suburban civic and residential centers. The underlying cylinder hull is a meter (3 feet, 3 inches) of titanium-reinforced “mooncrete” or lunar concrete, a mineral aggregate of anorthosite, ilmenite, and “KREEP,” an acronym for potassium (K), rare earth elements (REE) and phosphorus (P).The three “ground” panels are covered with an average 5-meter (16.4-foot) layering of landscaped topsoil.
The three “sky” panels are composed of quartz glass, vitreous silica prepared from pure quartz and noted for its transparency to ultraviolet radiation. Each “sky” panel is 3.2 kilometers (two miles) wide and 25.6 kilometers (16 miles) long, divided into eight square “windows” 3.2 kilometers on a side. Bridges connecting the “ground” panels span the “sky” panel at the junctions of these windows, seven bridges across each of the three “sky” panels, for a total of 21 “sky” bridges in all.
The basic element or building block of the “sky” panels is a cubical quartz glass prism 3.2 meters (10.4 feet) on a side, massing about 80 tonnes (90 tons). The prisms are mounted in a five-by-five titanium grid to form a square “frame” 16 meters (52 feet) on a side and three meters deep, with 25 prisms per frame.These frames are mounted, four ply, in a five-by-five array “pane” 80 meters (260 feet) on a side and 12.8 meters (41.6 feet) deep, with 100 frames (2,500 prisms) per pane.
The panes are mounted in a five-by-five “sash” 400 meters (1,312 feet) on a side, with 25 panes (2,500 frames or 62,500 prisms) per sash. Each of the eight windows is thus an eight-by-eight array of 64 sashes, containing 1,600 panes (160,000 frames or four million prisms), so each “sky” panel contains 512 sashes (12,800 panes or 1,280,000 frames or 32 million prisms).
Since there are three such panels, each colony has 24 windows (1,536 sashes or 38,400 panes or 3,840,000 frames or 96 million prisms) containing a combined mass of about 7,680 megatonnes (8,640 megatons) of quartz glass.
Docking ports called “bay blocks” at either end of the colony’s central axis rotate in the opposite direction, maintaining a “stationary” position around which the colony proper appears to rotate. Laser beacons line a five-kilometer approach path for incoming spacecraft. A solar power station (SPS) generating a gigawatt per hour is built into the port docking port.
Each docking port contains six docking bays, arranged around the axis like the chambers of a revolver. Each docking bay has six docks, arranged in a similar fashion around the centerline of the bay. Each dock can accommodate three 300-meter ships, for a total capacity of 108 ships. Zero-G industrial blocks are strung out along the axis between the docking ports and the end caps, standard-G industrial blocks are mounted on the exterior of the colony cylinder. All of the agriculture and industry is external to the colony proper, so all of the space within the colony cylinder is actual living space for the colonists, pure and unpolluted.(The O’Neill design specified solar power to supply the colony’s needs, but there’s another simple, effective and continuous sources of energy readily available, which is to run thermally conductive material from the interior to the exterior and from the north end cap to the south end cap and use the temperature differential—an extraterrestrial equivalent of “geothermal” power.)
Since the spacecraft bay blocks are necessarily at the center of the end caps, in line with the axis of rotation, the “mountainsides” on the interiors of these end caps are heavily urbanized. Six major cities are built at the bases of these mountains, three at either end, thinning out as they spread down the “foothills” and into the “valleys” toward the equator. (In a reversal of the mundane trend, it is the “hillside” which is the less desirable, “poor” side of town) The central zone at the equator is kept in a state of artificial “wilderness” dotted with a few small rural villages and highly prized resorts. Each colony thus contains six separate urban civic centers, six suburban residential zones and three rural recreational areas, each with its own distinct identity, as a safeguard against inbreeding and cultural stagnation.
Each of the three valleys within the colony is an elongated rectangle 32 kilometers (20 miles) long and 3.2 kilometers (two miles) wide, yielding a total area of 105 square kilometers (40 square miles). The six cities and their associated suburbs cover an area of 41.4 square kilometers (16 square miles) each. The three rural areas cover an area of 20.7 square kilometers (eight square miles) each, which must be shared evenly between the two urban/suburban centers at either end.
Travel from the docking bay and industrial blocks at the axis “down” to the residential areas in the valleys or “up” to the agricultural block ring is via elevator, usually depicted as a set of three vertical tubes spaced 120° apart. If so, riding them would be murder, due to the same Coriolis effect that produces the artificial “gravity” at the hull. As the elevator “rises” from the hull to the axis, the passengers are going to be pushed downspin at the same rate as they are inward, with the result that the “floor” is going to feel as if it’s been upended at a 45° angle.
The same applies going “down” from the axis to the hull, except that the push is going to be upspin. A body dropped from the axis to the hull would fall in a Nautilus-shell helical spiral, appearing to travel in an upspin arc around the axis until it finally impacted, not on the ground panel immediately below, but the ground panel upspin from there. The fall would take about five minutes 20 seconds and make one and one-third revolutions, with a terminal impact of 644 KPH (400 MPH).
Presuming that the elevator accelerates and decelerates at the same rate, minus the sudden sharp stop going from axis to hull, travel time would be the same as it is for a free fall, with the Coriolis effect converted into lateral forces on the vertically restricted passengers. That being the case, the best design for the elevator would be an upspin spiral for the cars going from axis to hull and a downspin spiral for the cars going from hull to axis. The cars would not run “vertically” (i.e., perpendicular to the “ground”), but drive “parallel” to the hull the entire trip.
