BETWEEN EARTH AND MOON

Concordia.
A world in motion.

A city turns inside this vast habitat. Follow one family from a quiet morning at home, through its streets and stations, and out into cislunar space.

ANGULAR MOMENTUM BALANCED

Spin seen from the spaceport (+X) end. Shares of the four city rotors' total. turn the other way from , so the city cancels itself.

−0.0626 rad/s · 100 s/turn−50.0%

+0.0626 rad/s · 100 s/turn+50.0%

CITY NET+0.0%

(industrial)−0.044 rad/s · 143 s/turn−4.0%

Momentum ringshold it and trim cargo moves+4.0%

NET+0.000%

Turns like a ship. A small thrust starts a turn and a small thrust stops it.
No gyroscopic side-step. Push a spinning body to turn it and it swings at right angles instead.
The rings take the swings. Cargo moves shift the industrial rotor by a fraction of a percent. The rings follow, and bearing motors trade the momentum for electricity, not propellant.

If all four city rotors turned one way, a 1° a day turn of the axis would take 4.5 MN at each hull end, nonstop. Cancelled in pairs, it takes about 4 kN for a day to start and a day to stop.

CLICK SCENE TO LOOK AROUND · WASD TO WALK

✳AN ORDINARY MORNING, 2,500 METERS FROM THE AXIS

CCONCORDIA

ASSEMBLING A WORLD IN MOTION

Four rotors, each 2,500 m in radius, turn once every 100 seconds to hold a city of about a million people at 1 g.

Enter begin the story
WASD walk, drag to look
M map
? every key

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Concordia.
A world in motion.

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Concordia.A world in motion.

Habitat atlas

Engineering layers

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Concordia.
A world in motion.