L3-CDH-SW-RTOS
CRITICAL
COMMAND CONTROL
Level 3 · software
Real-Time Operating System
VxWorks/RTEMS Radiation-Tolerant RTOS
Hard real-time operating system providing deterministic task scheduling and resource management
Purpose
Hard real-time operating system providing deterministic task scheduling and resource management
Context
Child of L2-CDH-SW
Principles
- ▸Preemptive priority scheduling ensures highest-priority tasks execute within deadline
- ▸Memory protection prevents task faults from corrupting other tasks or kernel
- ▸Watchdog timer support detects and recovers from task hangs
- ▸POSIX API compatibility enables portable application software
Typical implementations
- ▸VxWorks 7 (Wind River) - most used spacecraft RTOS (MER, MSL, Mars 2020)
- ▸RTEMS open-source RTOS (used on multiple NASA missions)
- ▸FreeRTOS for smaller embedded nodes (adapted for space with SEU protection)
Lunar considerations
- ▸RTOS must handle radiation-induced task corruption gracefully
- ▸Kernel must be patchable without full restart for 100-year software evolution
- ▸Memory scrubbing tasks run in background to correct single-bit errors
Specifications
Functional
| primary function | Hard real-time operating system providing deterministic task scheduling and resource management |
Interfaces
Provides
- Operating environment for all flight software
Requires
- Processor hardware executing RTOS
Cite this entry
Lunar Ark Codex. "Real-Time Operating System" (L3-CDH-SW-RTOS). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-CDH-SW-RTOS
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.