Autonomous Fault Protection Orbit Domain Modeling In Aerobraking

The Spacecraft Imbedded Distributed Error Response (SPIDER) Fault Protection architecture used on the Mars Reconnaissance Orbiter (MRO) incrementally developed capabilities based upon heritage spacecraft. The primary driving factors behind the improvements for this mission stemmed from several key concerns and development goals/requirements. Due to decreased risk tolerance at the program level, most hardware was cross-strapped on the spacecraft and additional autonomous responses were required to ensure the safety of the spacecraft to provide for a more robust handling of the system during high-risk events. Numerous interplanetary spacecraft missions have demonstrated the need to reduce maintenance effort during spacecraft operations. Aerobraking: the process of using atmospheric drag to dissipate orbital energy to achieve the desired science orbit following orbit insertion is a delicate process. The operations team is constrained by orbit geometry, 2-way light time delays, Martian weather, and a highly dynamic environment in which each pass through the atmosphere affects the subsequent orbit timing in a non-deterministic way. In the event of a fault on past missions, the operations team has required both constant contact with the spacecraft to diagnose the failure, and prompt issuance of the necessary ground commands to ensure spacecraft safety. In order to increase the autonomous response capability during Aerobraking and reduce the response time to faults, MRO developed a new set of capabilities, called the Navigation Performance Monitor (NPM). NPM, a member of the performance layer of SPIDER Fault Protection software, provides autonomous orbit domain modeling so the spacecraft may configure itself correctly for events within each orbit. During Aerobraking for MRO, NPM was called into action and successfully provided orbit modeling data to the Safe Mode software in response to two system faults; this demonstrated the robustness of our approach.