L2-CDH-BUS CRITICAL COMMAND CONTROL Level 2 · hardware

Data Bus Network

SpaceWire/Ethernet Hybrid Data Bus Network

The SpaceWire and Ethernet hybrid data bus network is a redundant communications backbone providing reliable data transport between all Lunar Ark processors and subsystems. Integrating deterministic SpaceWire links for critical data with time-triggered Ethernet for high-bandwidth bulk transfers, the architecture uses redundant ring or star-ring hybrid topologies and MIL-STD-1553 buses to prevent single-point failures. Operating on the Moon requires robust protocol-level error detection against radiation-induced single-event upsets, along with signal preservation over long inter-module cable runs. The physical infrastructure must also prevent lunar dust intrusion into connectors during extravehicular maintenance and survive persistent thermal cycling across a 100-year operational lifetime.

Redundant MIL-STD-1553, SpaceWire, and Ethernet backbone data network

Purpose

Provide reliable data transport between all Ark processors and subsystems

Context

Component of L1-CDH within the Lunar Ark system

Principles

▸SpaceWire provides deterministic, low-latency point-to-point links for critical data
▸Time-triggered Ethernet provides high-bandwidth, fault-tolerant networking for bulk data
▸Redundant bus topologies (ring, star-ring hybrid) prevent single-point-of-failure
▸Protocol layering separates physical transport from application-level data handling
▸Bus guardians prevent babbling-node faults from disrupting network traffic

Typical implementations

▸SpaceWire (ECSS-E-ST-50-12C) used on Gaia, BepiColombo, ExoMars
▸MIL-STD-1553B data bus (heritage, used on ISS, most spacecraft)
▸TTEthernet (AS6802) selected for NASA Orion spacecraft
▸SpaceFibre (ECSS-E-ST-50-11C) for next-generation high-bandwidth links

Lunar considerations

▸Radiation-induced single-event upsets require robust error detection in bus protocols
▸Long cable runs across Ark modules need signal integrity consideration
▸Thermal cycling affects connector reliability over 100-year mission
▸Dust intrusion into connectors during EVA/maintenance must be prevented