Sheet 0 · Overview
A cylinder you can walk around
Megastructure One is an O'Neill-type rotating habitat at Earth–Moon L5: a sealed cylinder 500 m long and 200 m in radius, spun about its long axis at 2.115 rpm so that the inside of the rim carries exactly one Earth gravity, inside a stationary regolith shield.
Layout along the axis
The 500 m floor is divided lengthwise into three bands. Zone A (169.5 m, 52.6 acres) holds farms, orchards and hamlets of cottages. The central walking strip (161 m, 50.0 acres) carries four villages round paved plazas, joined by a promenade that wraps the whole 1.26 km circumference, about three laps of a 400 m track. Zone B (169.5 m, 52.6 acres) is woods, meadows and estate houses round a reservoir. Two ring canals run along the zone boundaries. The end caps are 50 m-rise spherical domes (600 m overall). Docking is through two despun hubs on the axis, carried by the stationary shield, since a finite rotating port would need roll matching.
A 25 m luminous tube, the sun line, runs 480 m along the axis and lights the interior with piped sunlight and LED backup. From anywhere on the floor it hangs directly overhead, about 187 m up.
Gravity a = ω²r
| Radius | r (m) | a (m/s²) | g |
|---|---|---|---|
| Hull inner rim | 200 | 9.807 | 1.000 |
| Head height, standing | 198 | 9.709 | 0.990 |
| Half radius | 100 | 4.903 | 0.500 |
| Sun line surface | 12.5 | 0.613 | 0.0625 |
| Axis, docking hub | 0 | 0 | 0 |
ω = 2.115 rpm = 0.2214 rad/s, rim speed 44.3 m/s, period 28.4 s. Gravity is linear in radius. See M1-S-005.
Reading the cutaway Fig. 1
A 125° sector facing the viewer is removed from both bodies. Outermost is the stationary radiation shield: a dark matte enclosure of sealed regolith cells, 410 m across and 610 m long with flat end panels, that does not spin. Inside it, across a clearance gap, the pressure vessel turns: a 500 m Al-Li barrel with two 50 m-rise spherical domes, 600 m overall. The cut faces read outside to in: shield fill (sand, 2.8 m), gap, the 125 mm hull as a thin bright line, 0.3 m of soil under Zones A and B (brown), then the interior. Everything inside is modelled at true size: cottages about 8 m to the ridge, apartment blocks 15–19 m, hedges 1.4 m, trees 4–17 m, people 1.8 m. At this distance people are single pixels and the gardens read as fine grain, which is the point: the 100 m bar in the corner is the only scale cue.
Attached to the shield, not the rotor: two sun-facing solar wings of about 60,000 m² each (119,601 m² in total), six radiator panels standing edge-on to the sun on the shaded side (21,728 m² at 350 K), a sunlight collector mirror off the +x end feeding the sun line, and the two despun docking hubs that pass through the end panels on the axis. The hull and soil lines are drawn thicker than true scale so they survive as lines at this distance.