As NASA explores more challenging and complex missions, Model-Based Systems Engineering (MBSE) is seeing increased application for project planning and design. The Office of Safety and Mission Assurance’s Dr. John Evans, together with Dr. Steve Cornford and Dr. Martin Feather from NASA’s Jet Propulsion Laboratory, believes that Safety and Mission Assurance (SMA) has an opportunity to fully engage in the agency’s emerging methodologies. They are calling the new complementary SMA approach Model-Based Mission Assurance (MBMA).
In MBSE, a virtual model of the system is created, typically while it is still in the design or planning phase. The model is used as a singular reference source — a single point of truth — for system concept, requirements and design, and verification and validation and associated data. SMA can leverage that model to perform a variety of assurance analyses earlier in the life cycle reducing the occurrence of costly changes after the system design has become more hardened.
“SMA is often facing the N-1 problem,” said JPL Senior Engineer Steve Cornford. “By the time we analyze all of the project documentation, the team is onto a new design. We’re constantly playing catch-up. But if SMA processes are integrated with the model, it’s given the chance for the first time to have a direct effect on the current design, instead of just providing analysis results from the previous design.”
By using the MBSE model, SMA personnel will be able to run simulations and tests in real time, instead of having to wade through, in some cases, thousands of pages of documentation. In addition to being more timely, MBMA promises to be more flexible, faster and more cost-effective.
“It relieves the SMA practitioner from having to do more of the mechanical work, the work a computer can do, freeing them up to do the work that uses more of their skills,” said JPL Principal Engineer Martin Feather. “Let the computers do what they do best and humans do what they do best,” echoed Cornford.
This is a new frontier for SMA, as MBSE is still a relatively new approach for most of the agency. MBMA
“We’re developing more and more complex systems,” said Feather. “MBSE helps to manage that complexity by making sure nothing falls through the cracks. NASA continues to dare mighty things (to wit, the recent Pluto flyby). But a mission to a destination that has to orbit, land, collect samples and return them to Earth is significantly more complex. Engineering has to master that complexity and assurance has to keep up. We have to operate in that world.”
Read more about how SMA personnel worked with MBSE on the proposed Europa Mission or the Cascade Distillation System for the International Space Station.