SCL Ground Software

Spacecraft Command Language (SCL) combines a real-time Expert System and Command Interpreter, which enable both event-driven (using rules) and time-based procedural (using scripts) operation. The SCL Real-Time Engine (RTE) provides a multi-tasking executive for testbeds, simulations, control centers and a variety of industrial control solutions. Additionally, scripts and rules developed on a workstation can be deployed to embedded systems providing a symmetrical architecture between workstations and embedded systems.

Using a message oriented service called the SCL Software Message Bus, SCL is modular and loosely coupled which increases flexibility for scalability and the addition of mission unique software applications. The full-featured scripting language is designed for ease-of-use and does not require a software professional to develop scripts and rules. It also allows engineers, technicians and test conductors to author the SCL logic and exercise the system and the end-unit article.

The SCL system has provided 24/7 service for the several spacecraft missions. The FUSE Mission Operations Center was built around SCL and operated continuously for more than 8.5 years. The TacSat-2 Mission Operations Center used SCL for the one year Pathfinder mission for the Operational Responsive Space Office (ORS).


The SCL Ground software system includes:

  • SCL Real Time Engine
    • Rule Based Expert System
    • Scheduling Manager
    • Command Execution Manager
  • SCL Compiler
    • Script & Rule Compiler
    • Command Interpreter
  • SCL Viewer
  • Shared memory database
  • SCL Software Message Bus
  • SML - Command/Telemetry Definitions and Packet Formatter
  • Packet Decommutation
  • Packet Generation
  • RIMS Graphical User Interface (Optional)

For information on the SCL Flight Software click here.

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