Hub Station

TL;DR

  • Goal: Receive energy from the Dyson Swarm and transmit to Earth
  • Solution: Lunar Solar Power Station (LSP) — 40 stations on the Moon’s limbs
  • Efficiency: 18% (from Swarm to Earth)
  • Transmission: Microwaves through clouds, global rectenna network
  • Alternative (rejected): Orbital Hub at L1 — 10% efficiency, 7,900 km² radiators

Moon in the Project

The Moon serves three roles:

  1. Testing ground (years 4-6) — technology validation before Mercury
  2. LSP stations (years 6+) — energy reception from the Swarm and transmission to Earth
  3. Backup site — less risky alternative to Mercury

More on comparison with Mercury: Why Mercury?

Concept

The mirror swarm in Mercury’s orbit produces petawatts of energy. But this energy is concentrated sunlight. It needs to be converted to a form suitable for transmission to Earth.

flowchart TD
    A["Mirror Swarm (Mercury)"] -->|concentrated light| B["LSP stations on Moon"]
    B -->|"PV → Electricity → Microwaves"| C["Rectenna on Earth"]
    C --> D["Power Grid"]

Concept by David Criswell: placing receivers on the Moon’s surface with microwave power transmission.

Geometry: Why Limbs?

The Moon is tidally locked — one side always faces Earth. This creates a problem:

Position on Moon Sees Swarm? Sees Earth?
Near side Partially Yes
Far side Yes No
Limbs (edges) Yes Yes

Solution: 40 stations on the eastern and western limbs of the Moon.

Continuity of Operation

flowchart LR
    subgraph cycle["Lunar Month (29.5 days)"]
        A["Weeks 1-2"] -->|Western limb| B["Operating"]
        C["Weeks 3-4"] -->|Eastern limb| D["Operating"]
    end
    B --> E["Continuous transmission to Earth"]
    D --> E

    style cycle fill:#F5F5F5,stroke:#616161,color:#212121

Stations on both limbs ensure continuous operation throughout the lunar month.

Receiving Energy from the Swarm

Mirror Clusters

Swarm mirrors are organized into local clusters of 1,000-10,000 units. Each cluster:

  • Synchronizes internally (delay ~0.3 ms)
  • Directs reflected light to designated LSP station
  • Forms a virtual antenna ~100 km in diameter

Beam Spreading

Parameter Value
Distance Mercury → Moon ~100 million km
Virtual antenna diameter ~100 km
Beam spreading ~1 km
LSP receiver size 5-10 km

The beam spreads to ~1 km — the LSP receiver fully captures it.

Photovoltaics on the Moon

Parameter Value
Receiver area (per station) ~160 km² (12.6 × 12.6 km)
Total area (40 stations) ~6,400 km²
Flux on PV ~500 kW/m² (500 suns)
PV efficiency (concentration) ~45%
Type Multi-junction CPV, from lunar silicon
NoteWhy 6,400 km², not the full Swarm power?

The Dyson Swarm of 1.1 billion mirrors is capacity (~18 PW on Earth at full conversion). To deliver 1 PW to Earth, only ~55 million mirrors (5% of the Swarm) are active simultaneously, directing ~3.2 PW of optical power to the lunar receivers. At 6,400 km² total area, the flux is ~500 kW/m² — standard operating regime for concentrated PV systems. The remaining 95% of mirrors are reserve, in orbital dead zones, or allocated for future purposes (Mars, LSP scaling).

Transmission to Earth

Why Microwaves?

Parameter Microwaves Laser
Passes through clouds Yes No
Transmission efficiency ~85% ~70%
Earth receiver Rectenna Thermal boiler
Technology maturity High Medium

Microwaves selected — they pass through clouds and rain, enabling operation in any weather.

Global Rectenna Network

The Moon is visible ~12 hours from any point on Earth. Solution — global rectenna network:

Time UTC Moon over Active rectenna Energy goes to
00:00 Pacific Ocean Australia Asia
06:00 India Gobi (China) Asia, Europe
12:00 Africa Sahara Europe, Americas
18:00 Atlantic Atacama (Chile) Americas

Principle: Rectenna receives → HVDC cables transmit to global grid → consumers receive continuously.

Buffering: 1-2 hours of batteries smooth transitions between rectennas.

Advantage over solar: The Moon is visible day and night — easier to ensure continuity.

Earth Receivers (Rectenna)

Scale

Parameter Value
Target power 1 PW (50× global)
Power per rectenna ~1 TW
Number of stations ~100
Area per rectenna ~100 km² (10×10 km)

Locations

Rectennas are placed in sparsely populated regions — both in deserts for large-scale generation and closer to consumers:

Region Location Notes
Russia Yakutia Close to consumers, sparsely populated
Russia/Asia Kazakhstan Steppes, Central Asia
Europe Southern Spain Semi-desert, close to consumers
Scandinavia Finland/Sweden Northern Europe, sparsely populated
USA Nevada/Arizona Desert, central North America
Mexico Sonora/Chihuahua Desert, southern North America
Canada Saskatchewan/Manitoba Prairies, northern North America
China Xinjiang (Taklamakan) Large-scale generation, close to consumers
India Rajasthan (Thar) Close to consumers, high demand
Africa Sahara Large-scale generation
Asia Gobi (Mongolia) Large-scale generation
S. America Atacama (Chile) Large-scale generation
Oceania Central Australia Large-scale generation

Construction

A rectenna is an array of dipoles converting microwave radiation to electricity:

  1. Microwaves from LSP hit dipoles
  2. Dipoles generate alternating current
  3. Rectifiers convert to direct current
  4. HVDC transmits to grid

Rectenna efficiency: ~85%

Microwave Transmission Safety

Microwaves are safer than laser but require strict zoning.

Parameter Value
Intensity on rectenna (center) 10,000 W/m² (10× sun)
Sun at noon 1,000 W/m²
ICNIRP standard (public) 10 W/m²

Note: Power density of 10,000 W/m² matches real NASA (1978), JAXA, and modern SBSP concepts. See PMC: SBSP Review.

Territory Zoning

Zone Intensity Access
Center 10,000 W/m² Restricted zone (automated)
Middle 100–1,000 W/m² Technical personnel (limited)
Periphery <50 W/m² Security perimeter
Border <10 W/m² Meets ICNIRP standards 

flowchart TB
    subgraph rectenna["RECTENNA (100 km²)"]
        subgraph mid["Middle zone: 100-1000 W/m² — Technical personnel"]
            subgraph center["Center: 10,000 W/m² — Restricted zone"]
                A["Automated, no people"]
            end
        end
    end
    B["Periphery: <50 W/m² — Security"]
    C["Border: <10 W/m² — Safe"]

    style rectenna fill:#E8F5E9,stroke:#4CAF50,color:#1B5E20
    style mid fill:#FFF3E0,stroke:#FF9800,color:#E65100
    style center fill:#FFEBEE,stroke:#F44336,color:#B71C1C

Safety: Rectenna territory is fully fenced. System automatically shuts off when objects enter the beam (birds, aircraft).

Building LSP

Lunar Manufacturing

LSP is built from materials produced on the Moon — not delivered from Earth:

Component Material Source
Photovoltaics Silicon Moon (regolith)
Structure Aluminum Moon (anorthosite)
Antennas Aluminum Moon
Electronics Chips Earth (~0.1%)

Unified technology: The same Gen-2/Gen-3 robots that build factories on Mercury also work on the Moon. Lunar production is technology validation before Mercury. See Robot Bestiary.

Key advantage: On the Moon, heat from conversion dissipates into the ground. No giant radiators needed.

Logistics

  1. Lunar factory produces LSP modules from regolith
  2. Rovers transport modules to limbs (~500 km)
  3. Robots assemble stations on site

System Components

The Hub Station consists of three main subsystems working as unified infrastructure:

Lunar LSP Stations

  • Quantity: 40 stations on Moon’s limbs
  • Photovoltaic area: ~160 km² per station (total ~6,400 km²)
  • Materials: Multi-junction photocells from lunar silicon (Si), aluminum (Al) frames and supports
  • Production: Local, from lunar regolith

Microwave Transmitters

  • Location: On lunar LSP stations
  • Technology: Klystrons with 90% efficiency
  • Function: Convert electricity to microwaves for Earth transmission

Earth Rectennas

  • Quantity: ~100 stations worldwide
  • Size: ~100 km² each (10×10 km), total ~10,000 km² receiving area
  • Materials: Dipole arrays from aluminum (Al) or copper (Cu), silicon (Si) rectifier diodes — Earth production
  • Function: Receive microwaves and convert to direct current (HVDC)

Full System Composition

Note: Widget shows composition of lunar LSP stations (40 units). Earth rectennas are produced on Earth from local materials and are not part of the project’s space logistics.

System Efficiency

Stage Efficiency
Mirror reflection 90%
Orbit geometry 72%
Concentration to Moon 90%
PV on lunar stations 45%
DC → Microwaves (Klystron) 90%
Transmission Moon → Earth 95%
Atmospheric passage 95%
Rectenna on Earth 85%
Total efficiency 18%

Calculation: \(\eta = 0.90 \times 0.72 \times 0.90 \times 0.45 \times 0.90 \times 0.95 \times 0.95 \times 0.85 = 0.18\)

Comparison: Orbital Hub with laser — only ~10% efficiency due to double conversion (light → laser → heat).

Energy Distribution

The Dyson Swarm is capacity of ~18 PW (at Earth, after all losses). LSP Phase 1 is sized to receive from 5% of the Swarm (~55 million mirrors), delivering 1 PW to Earth. Power distribution:

Stage Recipient Power Notes
Swarm capacity (full) ~18 PW 1.1 billion mirrors
1. Reception (Phase 1) Moon (LSP) ~3.2 PW (optical) 55M mirrors (5% of Swarm)
↳ 1a. PV conversion Electricity ~1.45 PW PV efficiency 45%
↳ 2a. Transmission Earth (rectennas) 1 PW Via klystrons + RF
↳ 2b. Local Moon (furnaces, production) ~0.3 PW MRE, NaS, infrastructure
Reserve Scaling ~18-20 PW Mars, additional LSP stations

Details of lunar usage: - Furnaces: Melting regolith in solar furnaces, MRE electrolysis, materials production - Buffer: NaS batteries for peak load smoothing

Why not all to Earth? 1 PW = 1000 TW — this is 50 times global consumption (20 TW). It’s enough for complete decarbonization, synthetic fuels, and industrial growth. The remaining Swarm capacity (~95%) is reserve for scaling: additional LSP stations, Mars terraforming (1-5 PW direct), space expansion.

Alternative Architectures

Orbital Hub at L1

WarningConcept Rejected

Analysis showed economic infeasibility: 10% efficiency vs 18% for LSP, need to build 7,900 km² radiators in space.

Idea: Station at L1 point (Earth-Moon, 326,000 km from Earth) receives light from Swarm and transmits by laser to Earth.

Problem Hub (L1) LSP (Moon)
Efficiency 10% 18%
Radiators 7,900 km² in space 0 (ground)
Structure mass 15 million t in orbit ~178,000 t on surface
Construction In microgravity With gravity
Resources Delivery from Moon In-situ

Why such large radiators? At 35% efficiency at light→laser stage, about 65% of energy becomes heat. In vacuum, the only way to dump heat is radiation. At 1000K a radiator emits ~57 kW/m². For 0.45 PW, 7,900 km² area is needed.

Components:

Component Area Mass
Receiver (photovoltaics) 45 km² ~0.5 million t
Radiators 7,900 km² ~12 million t
Laser array — ~1.5 million t
Structure + systems — ~1 million t
Total ~15 million t

Cost (from Moon): $50-95 billion

GEO Station + Space Elevator

Alternative — geosynchronous orbit (36,000 km) with space elevator to reduce delivery costs.

flowchart LR
    A["Mirror Swarm"] --> B["SPS on GEO"]
    B --> C["Microwaves"]
    C --> D["Rectenna"]
    E["Space Elevator<br/>($100/kg vs $2000/kg)"] --> B

Advantages: - Station always above same point on Earth - Elevator reduces delivery cost 20×

Disadvantages: - Requires space elevator technology (not yet available) - Still needs radiators in space

Direct Solar Lasers

Concentrated light directly pumps laser medium — no PV, no electricity.

Parameter Value
Theoretical limit 31%
Practical (2025) 6-8%
Status Promising technology

Advantage: No diodes that degrade.

Architecture Comparison

Option Efficiency Radiators Maturity Status
Lunar LSP + Microwaves 18% 0 (ground) High Selected
Orbital Hub (L1) + Laser 10% 7,900 km² Low Rejected
GEO Station + Elevator 15-20% Present Medium Alternative

Conclusion: Lunar LSP is the most efficient architecture with twice the efficiency and no radiators in space.

See Also

Sources