Concordia
The aft face of the station from 25 km, with its ribbed shield, red rim lights, central tower and four landing masts.

Aft works

The back of the station is where the electricity comes in. Eight tethers run 7 km aft to the solar farm, four masts land the power, two reactors can restart everything after a blackout, and a ring of thrusters keeps the station steady.

See on the map

What you see

From 25 km the aft face reads as a shielded disc. Twenty-four buttress ribs, every 15 degrees, cross three ring frames at radii of 1,150 m, 1,900 m and 2,700 m. At the rim a girder and a louvred Whipple skirt carry 62 red marker lights, and in the centre a tower 350 m tall holds the blast iris over the service port. A white beacon on the tower pulses every 12 seconds.

Four tall landing masts carry HVDC tethers that run aft toward the distant solar farm.
Four tall landing masts carry HVDC tethers running aft toward the solar farm. Open this view

Four landing masts, each 500 m tall, stand at a radius of 1,900 m. Eight tethers run from the masts straight aft, about 7 km, to the hub of the solar farm, marked by a light every 250 m. The farm is a tethered power platform, held against the pull of the tethers by its own thrusters.

On two masts at the rim stand the black-start reactors, 800 m tall and behind shadow shields, with radiator petals turned edge-on to the Sun.

A black-start reactor on its tall mast sits behind a shadow shield with radiator petals edge-on to the Sun.
A black-start reactor on its 800 m mast behind its shadow shield, with radiator petals edge-on to the Sun. Open this view

Around the face sits a ring of twelve thruster pods, canted outward and wrapped in Whipple shields.

Inside the aft end

The spine ends here, 120 m wide, at a flat glazed wall with a boarding platform marked AFT TERMINUS. Beyond it the station is an engine room.

The converter hall is a row of twelve 50 m bays: HVDC valve halls in four towers, breaker bays, capacitor banks and cooling headers. Behind it are the control blister, a glazed dome on the tube, and two black-start switchgear halls. Last comes the vacuum service bay, with berths for tugs, a servicing craft and a tender, and a 350 m lined bore to the blast iris. Just ahead of the converter hall is the aft bearing gallery of Tsiolkovsky (Rotor 1).

Through arched windows in the spine, rows of HVDC valve halls and capacitor banks fill the converter hall.
Through arched windows, rows of HVDC valve halls and capacitor banks in the converter hall. Open this view

Open in the simulation: Aft Works · Aft Terminus Platform Open in the simulation: Aft Works · Service Bay

A rail garage near the aft end shelters a crawler and cradle for the hull's shielding service rail. Lane markers run out 5 km behind the station, green down the centre and red at the edges, to guide tugs and tenders to the service port.

How it works in brief

Solar platforms send direct current down the tethers. The converter hall turns it into the supply that feeds the station. HVDC is the efficient way to move up to 40 GW over 7 km, and the loss is a few hundredths of one percent. If the grid ever goes dark, the reactors restart the station from cold, running the bearings, pumps and communications and the first converter blocks. This is called a black start.

The thrusters trim the station's attitude and cancel the push of sunlight. They do not hold the orbit alone: keeping station at L5 takes the full thruster farm over weeks. Power, heat and thrusters are in Power and heat, and the tethers and solar farm in The exterior.

Key numbers

40 GWlanding capacity
4masts, 500 m tall
2 × 250 MWeblack-start reactors
12thruster pods
7 kmtether run to the solar farm
Go deeper: Sizes and electrical values

The power landing carries four bipoles at ±1.2 MV, 4.2 kA per conductor. A 7 km conductor of 4,200 mm² aluminium weighs about 80 t, and the ohmic loss is about 0.02 percent.

Each reactor delivers 250 MWe from about 700 MWt, and rejects about 470 MW through about 19,000 m² of radiator at 700 K. That is enough to restore the bearings, pumps, communications and the first converter blocks, not the full station demand.

The twelve thruster pods each carry nine 1 MW units, 108 MW class in all. With a specific impulse of 3,000 s, the ring makes about 4.4 kN. That cancels solar and thermal pressure of about 1 kN and trims attitude. Propellant is lunar metal vapour of the magnesium class, brought by tender.

Converter losses are about 1 percent of 40 GW, or 400 MW, rejected by two banks of radiator 250 × 250 m.

Visit

Open in the simulation: Aft Works: Far Read Open in the simulation: Aft Works: Power Landing Open in the simulation: Aft Works: Reactor Mast Open in the simulation: Aft Works: Thruster Ring Open in the simulation: Aft Works · Converter Hall Open in the simulation: Aft Works · Tsiolkovsky Aft Bearing Gallery

Nearby

The axis and the spine

At the centre of every rotor you weigh almost nothing, and a stationary tube 120 m wide runs the whole length of the station.

The exterior

From outside, Concordia is a grey cylinder 21 km long and 6.2 km wide.

The industrial rotor

Ehricke, the industrial rotor, is the factory floor. It is a skeleton of rings and girders 3.5 km long, turning opposite the city rotors, with refineries, tank farms, container...

  • The axis and the spine At the centre of every rotor you weigh almost nothing, and a stationary tube 120 m wide runs the whole length of the station.
  • The exterior From outside, Concordia is a grey cylinder 21 km long and 6.2 km wide.
  • Power and heat Concordia gets its power from the Sun, through solar platforms kilometres behind the station, and sheds all of it as heat through radiators.