Model Based Systems Engineering for CubeSat Mission Reliability

Model Based Systems Engineering (MBSE) is moving to the forefront of small spacecraft development. The benefits of SysML as a language for the elucidation of the system architecture for CubeSats is well understood and is implemented in standard model formats. Concurrently, the benefits of the evolving development of MBSE for assurance has been recognized and is emerging as Model Based Mission Assurance (MBMA), which promises the development of integral assurance stakeholder views into the model as well as the production of useful products from the model. In this regard, the assurance organizations of NASA, ESA, and JAXA are exploring jointly the potential benefits of MBSE and MBMA in anticipation of future joint projects in which an architecture for a flight mission will be shared in a SysML model. Traditionally, only mission-critical aspects of large systems have been able to justify the time and expense of creating reliability analyses. This work aims to make these analyses practical for a wide range of missions, from small to large to support architectural design decisions, rapidly and cost effectively, across organizations. In additions to exploring basic modeling concepts and communicating over the model, the partners have shown that reliability analysis can be generated from the model. These include early Failure Modes, Effects, and Critically Analysis (FMECA) and Fault Tree Analysis (FTA) based on the simulated mission. The intent is to test basic meta-model frameworks and compare these results across the agencies. One such basic framework employs SysML state machines as the basis for developing FMEAs and FTAs. When failures are modeled using this framework, plugins (developed by NASA under a Small Business Innovation Research project) for the SysML tool are able to automatically to generate a FMECA table and Fault Trees. The expected outcome of this project is a compilation of lessons learned across the 3 agencies (NASA-ESA-JAXA) to be shared with their assurance communities. In addition, comparisons and utility of SysML derived products from the model are planned. Finally, a framework for standardization to the extent possible will be proposed to facilitate model sharing in the future for more complex scenarios, as a result of lessons learned herein.