Model and Testing Based Assurance of COTS Systems in Space Radiation Environments

The use of COTS (Commercial Off-The-Shelf) parts in space for electronics is increasingly becoming a significant enabler for many capabilities during a mission. This STTR project will provide a better understanding of the feasibility of COTS electronics for High Performance Computing (HPC) in space environments which are already heavily shielded. This STTR team (Alphacore + Vanderbilt University) proposes innovative strategies, based on a complete system analysis of HPC COTS that include, but are not limited to, identifying the vulnerable aspects of COTS-based HPC systems, failure modes and their propagation through the system, as well as selected parts radiation testing, to mitigate radiation induced impacts to potential HPC systems in those highly shielded space environments, such as manned missions and human habitats. Thisproposal aimsto(i)evaluate radiation performance of sub-systems of an HPC system, (ii) develop mitigation techniques for each sub-system, and (iii) determine if NASA specs for space deployment can be met by the redesigned system using COTS components. Theradiationeffectsmodelhas two aspects: systems modeling language (SysML), and goal structuring notation (GSN), from which it can produce reliability objects for evaluating mission reliability of spacecraft: discrete Bayesian Nets (BN) and Fault Trees (FT).UsingSysML, the target system is modeled via functional decomposition diagrams, architectural diagrams via block diagram models, fault propagation diagrams, which constitute a complete description of a spacecraft (or subsystem) with multiple functions. GSN is used to create a visual argument structure highlighting goals and strategiestoachieve required top-level function in given space environment for mission life. These goals and strategies are supported by solutionssuch asradiation testing or mitigation strategies.The methods will be extensively verified and validated by multiple irradiation tests (neutron, proton, alpha). The use of COTS (Commercial Off-The-Shelf) parts in space for electronics is potentially a significant enabler for many mission capabilities. This STTR program will provide a better understanding of the use of COTS electronics for High Performance Computing (HPC) in space environments which are already heavily shielded. The Alphacore + Vanderbilt University team proposes innovative strategies, including failure modes, to mitigate radiation induced impacts to potential HPC systems in those highly shielded space environments, such as manned missions and human habitats. In this STTR program, the team will commercialize VU’s “Integrated System Design for Radiation Environments”, which involves space radiation modeling and a complete analysis of the COTS-based HPC systems. The methodology includes modeling and testing for an appropriate space relevant environment. Further, since not all parts in such HPC systems can be tested, we will develop a method for understanding which parts are susceptible to radiation damage and which are crucial to be on the list of potential test candidates. TECHNICAL OBJECTIVES: - Develop a better understanding of the feasibility of COTS electronics for HPC in space environments. - Demonstrate strategies based on a complete system analysis of an HPC COTS system to discover the radiation-induced fault modes of the HPC system, and develop mitigation strategies so that the COTS HPC system stays within specification during the mission. WORK PLAN - Phase I: Identify possible fault behaviors resulting from single events in the HPC system. Evaluate the right level of abstraction to represent the faults and their effects in the HPC system. Select an HPC system for demo in Phase I (consulting with NASA the mission needs). Breakdown the system into sub-systems along functional and physical lines. Use RTL-Level simulations to evaluate each sub-system, find radiation effects data for each component in each sub-system. Construct fault propagation networks by identifying fault effects or anomalies resulting from the fault and whether those anomalies and effects can be passed to other components, boards, or systems in the HPC network. Choose one or two failure effects and create a discrete Bayesian net that represents the failure probability for that failure effect. SEE test design and experiment (pulsed laser Phase I). Develop mitigation techniques for the most vulnerable sub-system, to be tested in Phase II.
Benefits: The results from this project will be relevant to any NASA mission or project and any space mission that intends to send humans beyond LEO (Low Earth Orbit) with a High-Performance Computing (HPC) system. An HPC ecosystem is also of interest to Science Mission Directorate (SMD). Immediate infusion targets include Mars Fetch Rover, WFIRST/Chronograph, Gateway, SPLICE/Lunar Lander. This proposal addresses NASA needs described in the latest 2015 NASA Technology Roadmaps such as Space Weather Forecasting. Private enterprises that have based their business on spaceflight can make use of this technology to reduce their loads when embarking on missions to space. Future constellations of small communications satellites will blanket the Earth with Internet connectivity as well. Other countries are also participating in space exploration driving the global market for radiation hardened electronics.