Dome Assembly

TL;DR

  • Purpose: Pressurized shells for new factories
  • Production: Factory-Replicator (F-R)
  • Size: ~1500 m² (~50x30 m), height 6-8 m
  • Material: 8-layer composite (fiberglass + Al foil)
  • Throughput: 1 dome = 2-3 days of materials

Overview

A Dome is a pressurized shell for factories, creating a 0.1 atm O₂ atmosphere for equipment operation. Each new factory requires a dome before startup.

Two dome options:

Option Application Installation time
Pre-assembled inflatable First factory (bootstrap) 4-8 hours
On-site assembly Standard production 4 days

Where produced (standard mode): At the Factory-Replicator (F-R) in the “Cutting + Dome Welding” zone (200 m²). Fabric arrives through the airlock from external spool storage. Finished panels exit through the airlock and are delivered by Crabs-M to the installation site.

Option 1: Pre-assembled Inflatable Module (Bootstrap)

For first factory assembly — bring a ready inflatable module from Earth. This is critical for the energy autonomy checkpoint.

Parameter On-site assembly Inflatable module
Time 4 days 4-8 hours
Mass ~8 t 10-12 t (+2-3 t)
Robots 6 Moles-M (Gen-2!) 6 Centaurs-Z (Gen-1)
Risk High Low

Analog: Bigelow Aerospace BEAM module on ISS (16 m³, 1.4 t) — operating successfully since 2016.

Deployment Process

# Operation Robots Time
1 Unload module Crab-Z ×4 1 hour
2 Position on site Centaur-Z ×6 1 hour
3 Inflate with N₂ (0.1 atm, imported from Earth) Automatic 30 min
4 Connect airlock Centaur-Z ×4 1 hour
5 Leak check Centaur-Z ×2 30 min
Total 4 hours

Why inflatable module for bootstrap:

  • Does not require Gen-2 robots (Moles-M not yet manufactured)
  • Deployment time compatible with energy autonomy checkpoint (12-24 h)
  • Proven technology (BEAM on ISS since 2016)

Details: First Factory Assembly (Bootstrap)

Option 2: On-site Assembly (Standard Mode)

For all factories after the first — dome production from local materials.

Dome Construction

Parameter Value
Dimensions ~50x30 m (~1500 m²)
Height 6-8 m
Dome mass ~8 t*
Internal atmosphere 0.1 atm O₂
Layers 8 (alternating silicate fabric + Al foil)
Pressure 0.1 atm (10 kPa)

*Finished dome: fabric ~6 t + frame ~1.5 t + airlock ~0.5 t. Bootstrap inflatable module 10-12 t includes reinforced frame.

Multi-layer Structure

The dome consists of 8 alternating layers:

Layer Material Thickness Function
1 (outer) Fiberglass 2 mm Micrometeorite protection
2 Al foil 50 μm Hermetic seal
3 Fiberglass 2 mm Strength
4 Al foil 50 μm Redundant seal
5 Fiberglass 2 mm Strength
6 Al foil 50 μm Redundant seal
7 Fiberglass 2 mm Strength
8 (inner) Al foil 50 μm Final seal

Benefits of multi-layer design: - Redundancy — single layer puncture is not critical - Strength — fiberglass withstands micrometeorite impacts - Hermeticity — 4 layers of Al foil ensure <0.1%/day leakage

Layer Lamination Process

Layers are bonded via thermal lamination:

  1. Fiberglass (150°C) + Al foil fed to heated calender
  2. Pressure 0.5 MPa, speed 2 m/min
  3. Al foil mechanically anchors in fiberglass pores
  4. Finished 8-layer roll cools and is wound

Assembly Process

flowchart TD
    subgraph INPUT["INPUT"]
        FABRIC["Composite fabric<br/>8-layer<br/>~8 t per dome"]
    end

    subgraph CUTTING["CUTTING"]
        TEMPLATE["Dome template<br/>50x30 m"]
        CUT["Cutting table<br/>laser cutting"]
    end

    subgraph WELDING["WELDING"]
        PANELS["Dome panels"]
        ULTRASONIC["Ultrasonic welding<br/>of seams"]
        SEAL["Joint sealing"]
    end

    subgraph TESTING["TESTING"]
        PRESSURE["Pressure test<br/>0.15 atm"]
        LEAK["Leak detection<br/>mass spectrometer"]
    end

    subgraph OUTPUT["OUTPUT"]
        DOME["Finished dome<br/>~8 t, ~1500 m²"]
    end

    FABRIC --> TEMPLATE
    TEMPLATE --> CUT
    CUT --> PANELS
    PANELS --> ULTRASONIC
    ULTRASONIC --> SEAL
    SEAL --> PRESSURE
    PRESSURE --> LEAK
    LEAK --> DOME

    style INPUT fill:#f0e68c
    style CUTTING fill:#fff3cd
    style WELDING fill:#d4edda
    style TESTING fill:#b8e0d2
    style OUTPUT fill:#cce5ff

Layout in Factory-Replicator

“Cutting + Dome Welding” zone (200 m²) at F-R:

Equipment Area Operation
Cutting table 10x5 m ~80 m² Laser cutting panels by template
Ultrasonic welding zone ~80 m² Panel welding + seam sealing
Seam inspection zone ~40 m² Ultrasonic testing, visual inspection, tensile test

Fabric spool storage — on external storage (vacuum). Fed through airlock as needed (JIT).

Full pressure test — conducted AFTER installation on site (50x30 m dome cannot be tested entirely inside 200 m² zone). Factory only controls seam quality.

Production Stages

1. Composite Fabric Cutting

Composite fabric arrives from the silicate line in rolls.

Parameter Value
Source Silicate line
Roll width 2-3 m
Roll mass 200-300 kg
Cutting table 10x5 m (laser cutting)

Process: 1. Roll is unwound on cutting table 2. Laser cutter cuts panels by template 3. Panels are marked (number and position in dome)

Waste: ~5% (scraps go to repair patches)

2. Seam Welding

Panels are joined by ultrasonic or thermal welding.

Parameter Ultrasonic Welding Thermal Welding
Temperature 150-200°C 300-400°C
Speed 5-10 m/min 2-5 m/min
Seam strength 90-95% of material 85-90%
Power consumption 2-5 kW 5-10 kW

Method selection: Ultrasonic welding preferred (faster, less heating, stronger seam).

Seam quality control: - Visual inspection (camera) - Ultrasonic testing (UT) — void detection - Tensile test (sampling)

3. Joint Sealing

Additional sealing of seams to maintain 0.1 atm O₂ atmosphere.

Material Application
Al tape Seams between panels + critical seam backup

Process: 1. Seam is degreased 2. Al tape placed over seam 3. Ultrasonic welded (150-200°C, 5-10 m/min) 4. Pressed with roller (1-2 atm pressure)

4. Testing (at Installation Site)

Each dome undergoes hermetic testing after on-site installation (factory only controls seams).

Pressure Test

Parameter Value
Test pressure 0.15 atm (150% of working)
Hold time 1 hour
Pass criterion Pressure drop <1%

Process: 1. Dome is inflated with oxygen to 0.15 atm 2. All valves are closed 3. Pressure is checked after 1 hour 4. If drop >1% — search for leak

Leak Detection

If test shows leak, mass spectrometer with helium is used.

Parameter Value
Indicator gas Helium (He)
Sensitivity 10⁻⁹ atm·cm³/s
Method Mass spectrometer sweep around dome

Process: 1. Dome is filled with O₂ + 10% He mixture 2. Mass spectrometer sweep outside 3. Helium detection = leak found 4. Leak is patched + Al tape (ultrasonic welded)

Material Balance

Per 1 dome (~1500 m²):

Material Mass Source
8-layer composite fabric ~8 t Silicate line
Al tape (seam sealing) ~30 kg Rolling
Fasteners (bolts, nuts) ~50 kg WAAM + grinding

Silicate line throughput: ~28 t fabric/day → 3-4 domes/day

On-Site Dome Installation

After fabrication, the dome is transported to the new factory installation site.

Stage Time Robots
Site preparation 1 day 6 Moles-M
Frame installation 1 day 4 Centaurs-M
Dome installation 1 day 6 Centaurs-M
Perimeter sealing 0.5 day 2 Centaurs-M
Pressure test 0.5 day Automated
TOTAL 4 days

Dome frame: - Steel Fe arches (rolled) - Arch spacing: 5 m - Foundation: piles into regolith (1-2 m depth)

Power Consumption

Component Power
Cutting table (fiber laser 5 kW) 5 kW
Ultrasonic welding 5 kW
Testing equipment 2 kW
Transport and installation 10 kW
TOTAL ~22 kW

Dome Maintenance

After installation, domes require minimal maintenance.

Operation Frequency Performer
Seam inspection Monthly Centaur-M + camera
Oxygen top-up As needed Automated
Puncture repair As occurs Centaur-M (patch)
Dome replacement 10-15 years Full replacement

Typical punctures: Micrometeorites >1 mm may puncture 1-2 layers. Repair takes 2-4 hours (patch + Al tape).

See Also