Control Electronics

TL;DR

  • Purpose: Launch control and monitoring systems for Mass Drivers
  • Mass: ~6 t (97.5% local, 2.5% import)
  • Import: ~142 kg (controller boards, MOSFET chips, sensors)
  • Local: ~5.6 t (NaS capacitors, Al heatsinks, housings)

Overview

Control electronics is the “brain” of the Mass Driver, managing sequential coil activation, monitoring launch parameters, and ensuring safety.

System Architecture

flowchart TD
    subgraph CENTRAL CONTROL
        MASTER["Main Controller<br/>(redundant)"]
    end

    subgraph TRACK MONITORING
        SENSORS["2,150 sensors<br/>(current, T, position)"]
        CAMERAS["50 cameras<br/>(optical monitoring)"]
    end

    subgraph POWER ELECTRONICS
        MOSFET["1,000 MOSFET switches<br/>(coil activation)"]
        CAPS["Capacitor banks<br/>(4.7 GJ)"]
    end

    subgraph COMMUNICATIONS
        FIBER["Fiber optics<br/>(3 km backbone)"]
    end

    SENSORS --> MASTER
    CAMERAS --> MASTER
    MASTER --> MOSFET
    MOSFET --> CAPS
    FIBER --> MASTER

    style CENTRAL CONTROL fill:#f0e68c
    style TRACK MONITORING fill:#fff3cd
    style POWER ELECTRONICS fill:#d4edda
    style COMMUNICATIONS fill:#cce5ff

System Components

1. Main Controller

Parameter Value
Type Industrial PLC
Processor ARM Cortex-A72 (4 cores, 1.5 GHz)
Memory 8 GB RAM, 128 GB SSD
Redundancy Dual backup (primary + backup)
Board mass ~5 kg (2 units = 10 kg)
Housing mass (Al) ~40 kg (2 units)
Board source Imported from Earth (~10 kg)
Housing source Local (Al)

Functions: - Acceleration trajectory calculation - Sequential coil activation control - Parameter monitoring - Emergency shutdown

2. Section Control Units

Parameter Value
Quantity 34 units (every ~30 m)
Function Control of ~30 coils
Processor ARM Cortex-M4 (168 MHz)
Interface Ethernet (fiber optic)
Board mass ~450 g
Housing mass (Al) ~4.5 kg
TOTAL board mass ~15 kg
Board source Imported from Earth (~15 kg)
Housing source Local (Al)

3. Sensors

Sensor Type Quantity Function Mass
Hall effect current sensors 1000 (1 per coil) Coil current monitoring 1 kg
Thermocouples 1000 Coil temperature monitoring 1 kg
Position sensors 100 Projectile position detection 10 kg
Accelerometers 50 Frame vibration 5 kg
TOTAL 2,150 ~17 kg

Source: Imported from Earth

4. Power Electronics

MOSFET Switches

Parameter Value
Quantity 1000 (1 per coil)
Voltage 1000 V
Current 1000 A
Switching time <1 us
Chip mass ~50 g
Heatsink mass (Al) ~400 g
TOTAL module ~450 g
Chip source Imported from Earth (~50 kg per MD)
Heatsink source Local (Al)

Function: Coil on/off switching with microsecond precision.

Localization: Heatsinks and housings manufactured from local Al, only chips imported.

NaS Capacitor Banks

Parameter Value
Type Sodium-sulfur (NaS)
Capacity ~1,300 kWh
Voltage 1000 V
Energy 4.7 GJ (per shot)
Mass ~5 t
Source 100% local

Materials: Na (anode) + S (cathode) + Al₂O₃ beta-alumina (separator) — all from regolith.

Function: Energy storage between shots (2-3 minutes charging).

Details: MD Theory, NaS TRL 9

5. Communications and Networks

Component Length/Quantity Function
Backbone fiber optics 3 km Connection to control center
Ethernet cables 10 km Control unit connections
Wi-Fi access points 10 units Backup communications, diagnostics
Mass ~50 kg

Software

Launch Algorithm

1. Readiness check:
   - Projectile in position (position sensors)
   - Capacitors charged (>95%)
   - Cooling active (T < -140C)
   - Track clear (cameras)

2. Acceleration (0.4 sec):
   - T=0: Activate coil #1
   - T=0.4 ms: Activate coil #2 (average)
   - ...
   - T=0.4 sec: Activate coil #1000 -> launch

3. Trajectory control:
   - Actual velocity vs calculated
   - Timing adjustment for subsequent coils

4. Completion:
   - Projectile exited track (optical sensors)
   - Coil deactivation
   - Capacitor charging (2-3 min)

Material Balance

Electronics per 1 Mass Driver:

Component Import Local Total
Controller boards ~25 kg ~193 kg (Al housings) ~218 kg
Sensors ~17 kg — ~17 kg
MOSFET chips ~50 kg ~400 kg (Al heatsinks) ~450 kg
NaS Capacitors — 5 t 5 t
Cables, fiber optics 50 kg — 50 kg
TOTAL ~142 kg ~5.6 t ~5.7 t

Localization: ~97.5% by mass (NaS capacitors + heatsinks + housings).

Conclusion: Only boards and chips imported (~142 kg/MD). NaS capacitors and housings — local production.

Electronics Installation

Stage Duration Robots
Backbone fiber optic installation 2 days 5 Centaur-M
Control unit installation (34 units) 3 days 10 Centaur-M
Sensor connection (2,150 units) 1 week 15 Centaur-M
MOSFET module mounting 3 days 10 Centaur-M
Communications testing 1 day Automated
TOTAL ~2 weeks

Electronics Power Consumption

Component Power
Main controller 200 W
Control units (34 units) 3.4 kW
Sensors (2,150 units) 2 kW
MOSFET switches (standby) 1 kW
Cameras and communications 1 kW
TOTAL ~8 kW (continuous)

Peak power: 400 MW during launch (from capacitors, not grid).

Maintenance

Operation Frequency Performer
Sensor calibration Monthly Automated
Fiber optic inspection Quarterly Centaur-M
MOSFET module replacement On failure Centaur-M
Software update As needed Remote

Service life: - Controllers: 10-15 years - Sensors: 5-10 years - MOSFET switches: 2-5 years (depends on operating mode) - Capacitors: 2-3 years (charge/discharge cycles)

Quality Control

Parameter Control Method Specification Action on Deviation
Coil switching time Oscilloscope <1 us deviation Replace MOSFET
Current sensor accuracy Calibration +/-1% Recalibrate
Fiber optics OTDR (reflectometer) Losses <1 dB/km Replace section
Electronics temperature Thermocouples <+50C Improve cooling

See Also