Mars Project Software Systems Engineering Improvements

Increasingly challenging missions are characterized by an expansion of the mission-critical role of software. In the Mars projects, Entry, Descent, and Landing (EDL) are software controlled. EDL relies on software timing and functionality, leading to such things as second chance flight software operating as a copilot on the backup flight computer. Therefore, much of the project risk lies in robustness of software. Within the laboratory, the Project Software Systems Engineering (PSSE) has the responsibility of planning, systems engineering, and overseeing all project software while development organizations deliver domain specific software, such as Command & Data Handling (C&DH) software, Sample Recovery Helicopter (SRH), Guidance, Navigation, & Control (GN&C) software, Vision Compute Element (VCE) software, Ground Data System (GDS) software, Simulation Support Equipment (SSE) software, etc. The software lifecycle chosen for Mars project software development is the incremental lifecycle, wherein the content and scope of each software release will be built upon the delivered capabilities of previous releases to achieve incremental functionality. In this context, the challenge stems from the surge in detail and complexity where current software systems engineering practices will be hard-pressed to keep up. This paper describes an assessment of software systems engineering processes, specifically in the NASA Mars Science Laboratory Curiosity Rover, Mars 2020 Perseverance Rover, and the planned Mars Sample Retrieval Lander, and identifies potential efficiencies and improvements. It also describes the innovations in Mars project software systems engineering and makes recommendations as to how these evolved and what new methods and techniques should be infused into flight projects at the laboratory.