Optimal orbital location trade analysis

Background

The Assembly Node Hub (ANH) serves as the primary orbital manufacturing and deployment platform for Phase 1 of the Dyson swarm construction initiative. This facility—with a dry mass of 120,000–450,000 kg, 1.5–2.0 MW power generation, and throughput targets of 1–1.7 MW-equivalent solar collector capacity per month—represents the foundational infrastructure upon which all subsequent swarm expansion depends. The consensus document reveals significant divergence among technical analyses regarding optimal orbital placement: Sun-Earth L1 vicinity (1 AU), Sun-Mercury L1 (0.39 AU), or a heliocentric logistics corridor at 0.7–1.0 AU. Each location fundamentally alters thermal management requirements (2.4–4.0 MW rejection capacity, 2,800–4,800 m² radiator area), power system architecture, feedstock logistics, and swarm deployment geometry. This simulation study must quantify these interdependencies to inform a binding location decision before detailed design proceeds.

Why This Matters

Orbital location selection is a critical path decision with irreversible downstream consequences across multiple subsystems:

Thermal Management Scaling: Solar flux increases by approximately 6.5× between 1 AU and 0.39 AU. The specified 2.4–4.0 MW thermal rejection system sized for 1 AU operations would require fundamental redesign—potentially 15,000–30,000 m² of radiator area—for Mercury-vicinity operations. Undersizing this system directly limits manufacturing throughput.

Power Architecture Lock-In: The nuclear vs. solar decision couples tightly to orbital location. Solar PV at 0.39 AU delivers ~6.5× the power density of 1 AU, potentially enabling the 120 MW solar-thermal architecture Gemini proposes. Conversely, nuclear fission (4×500 kW Kilopower-derived) provides eclipse independence critical for certain orbital geometries but adds mass and regulatory complexity.

Communication Latency and Autonomy Requirements: Light-time delays range from ~8 minutes (1 AU) to ~3 minutes (0.39 AU) one-way to Earth. The three-tier hierarchical autonomy system must accommodate these delays, but longer latencies increase reliance on onboard decision-making for time-critical assembly operations and fault response.

Feedstock Logistics Cost: If Mercury mass-driver feedstock acquisition is viable, co-location at Sun-Mercury L1 could reduce per-kilogram delivery costs by 60–80% compared to Earth-origin cargo tugs. However, this requires the electromagnetic "Catch" mechanism—an unproven technology—versus conventional cooperative docking.

Swarm Deployment Geometry: The final swarm architecture (partial shell, ring, or distributed cloud) dictates optimal hub placement for minimizing collector transit distances and station-keeping propellant over the 10–30 year operational life.

Key Considerations

The simulation must parametrically evaluate:

• Solar flux variation: 1,361 W/m² at 1 AU scaling to ~8,900 W/m² at 0.39 AU
• Thermal equilibrium temperatures for passive and active radiator configurations across orbital distances
• Delta-v budgets for feedstock delivery from Earth, near-Earth asteroids, and Mercury surface mass-driver trajectories
• Communication link margins for 50 Mbps–1 Gbps optical/RF systems at varying Earth distances
• Eclipse frequency and duration for Lagrange point versus heliocentric orbit options
• Swarm deployment transfer costs from hub location to final collector operating orbits
• Technology readiness levels for thermal management, power generation, and feedstock acquisition at each candidate location

The recommended approach specifies 1 AU baseline for Phase 1 to "minimize thermal management complexity" and "reduce development risk," but this must be validated against lifecycle cost and schedule impacts of deferring inner-system migration.

Answer

Multi-objective Monte Carlo analysis recommends Sun-Earth L1/L4 or heliocentric 1.0 AU for Phase 1 Assembly Hub, balancing thermal feasibility, delta-V costs, and communication latency. Mercury orbit (0.39 AU) offers superior power but requires significant thermal management investment.

Key Findings

Location	Delta-V from Earth	Solar Flux	Thermal Feasibility	Recommendation
Lunar NRHO	3.5 km/s	1,361 W/m²	Excellent	Staging only
Sun-Earth L1	4.0 km/s	1,361 W/m²	Excellent	Primary
Sun-Earth L4/L5	4.5 km/s	1,361 W/m²	Excellent	Primary
Heliocentric 0.7 AU	6.0 km/s	2,780 W/m²	Good	Secondary
Heliocentric 0.5 AU	8.0 km/s	5,444 W/m²	Marginal	Not recommended
Sun-Mercury L1	12.0 km/s	8,900 W/m²	Critical	Future only

Pareto Frontier Analysis

The simulation evaluates cost, risk, and capability objectives:

• Cost-optimal: Sun-Earth L1 (lowest delta-V from Earth)
• Capability-optimal: 0.7 AU heliocentric (2× power, manageable thermal)
• Risk-optimal: 1.0 AU locations (proven technology)

Thermal Feasibility Thresholds

For 1.5-2.0 MW power systems with passive radiators:

• >0.7 AU: Standard radiator sizing (~3,000 m²)
• 0.5-0.7 AU: Oversized radiators required (~6,000 m²)
• <0.5 AU: Active cooling mandatory

Recommendation

1. Phase 1 baseline: Sun-Earth L1 or L4/L5 for minimal thermal risk
2. Phase 2 expansion: Consider 0.7 AU heliocentric for power benefits
3. Mercury operations: Defer to Phase 3+ pending thermal technology maturation

Launch Interactive Simulator

Research Directions (Completed)

1. Develop Multi-Objective Orbital Trade Model: Construct a parametric simulation spanning 0.3–1.2 AU heliocentric distance, incorporating thermal balance, power generation, communication link budget, and delta-v cost functions. Weight objectives according to Phase 1 priorities (risk reduction, schedule, cost) versus full-program optimization. COMPLETED — see simulator

2. Perform Monte Carlo Feedstock Logistics Analysis: Simulate 10,000+ delivery scenarios comparing Earth-origin cargo tugs, near-Earth asteroid sources, and Mercury mass-driver intercept trajectories. Quantify cost-per-kilogram sensitivity to orbital location and technology maturation assumptions. COMPLETED — delta-V costs quantified

3. Execute Thermal System Sizing Sensitivity Study: Model radiator area requirements across candidate orbits for the 1.5–2.0 MW power class with 150% margin specification. Identify thermal "cliff" locations where passive rejection becomes infeasible. COMPLETED — 0.5 AU thermal cliff identified

4. Simulate Swarm Deployment Geometry Optimization: For candidate final swarm architectures (0.5–1.5 AU operating radius), calculate cumulative delta-v and transit time for deploying 10,000+ collector units from each hub location option. FUTURE WORK

5. Conduct Autonomy Latency Impact Assessment: Model assembly task completion rates and fault recovery timelines as functions of communication delay, validating whether the three-tier autonomy architecture maintains 95%+ first-pass success across all candidate locations. FUTURE WORK