Flight Software

SCL for Flight Systems

Spacecraft Command Language (SCL) is a high-performance execution engine for flight embedded systems. The system provides a multi-scripting executive that allows priority-based parallel execution of scripts and rules. The SCL Real Time Engine (RTE) contains a rule-base Expert System and a command interpreter. These Expert System and command interpreter share the same code and behavior allowing the system to reduce the amount of code that must be verified and validated before flight.

The SCL system is designed to allow the same software architecture to be used for both flight and ground segments. Scripts developed and tested on the ground can be reused and moved directly onto the flight system with no loss of knowledge. The flight system allows closed loop control to be accomplished where ground contact is normally needed to make critical decisions. This paradigm shift reduces the need for ground personnel and lowers cost of ownership.

The flight system is further enhanced by two patented flight system capabilities. The Autonomous Tasking Engine (ATE) is an on-board planning, scheduling and re-planning system. The On Orbit Checkout Engine (OOCE) is a methodology to rapidly perform a functional checkout of all system interfaces and subsystems. The ATE and OOCE systems have become key technologies for the success of the Operationally Responsive Space (ORS) satellite. OOCE and ATE have been used on the following ORS satellites:

  • TacSat-2 – Launch December 2006, successful 1 year mission
  • TacSat-3 – Launch Date May 19, 2009
  • TacSat-4 – Launch Date September 2009
  • ORS Sat-1 – under development
  • PnPsat – awaiting launch.

The SCL flight system can be integrated on top of a legacy system. The SCL flight software is designed to be reusable and has been fielded on many satellite missions and is the Autonomy flight software for the NASA Orion Crew Exploration Vehicle (CEV).

The SCL Flight software system includes:

  • SCL Real Time Engine
    • Rule Based Expert System
    • Scheduling Manager
    • Command Execution Manager
  • SCL shared memory database
  • SCL decommutation engine
  • SCL Packet Generator
  • Software Message Bus - Compatible with the Real-Time Operating System
  • SCL Compiler - workstation development environment
  • Graphical User Interface - workstation development environment