A paper discusses techniques for protecting against faults in spacecraft designed and operated by NASA's Jet Propulsion Laboratory (JPL). The paper addresses, more specifically, faultprotection requirements and techniques common to most JPL spacecraft (in contradistinction to unique, mission specific techniques), standard practices in the implementation of these techniques, and fault-protection software architectures. Common requirements include those to protect onboard command, data-processing, and control computers; protect against loss of Earth/spacecraft radio communication; maintain safe temperatures; and recover from power overloads. The paper describes fault-protection techniques as part of a fault-management strategy that also includes functional redundancy, redundant hardware, and autonomous monitoring of (1) the operational and "health" statuses of spacecraft components, (2) temperatures inside and outside the spacecraft, and (3) allocation of power. The strategy also provides for preprogrammed automated responses to anomalous conditions. In addition, the software running in almost every JPL spacecraft incorporates a generalpurpose "Safe Mode" response algorithm that configures the spacecraft in a lower-power state that is safe and predictable, thereby facilitating diagnosis of more complex faults by a team of human experts on Earth.
This work was done by Paula Morgan of Caltech for NASA's Jet Propulsion Laboratory. For more information, download the Technical Support Package (free white paper) at www.techbriefs.com/tsp under the Information Sciences category.
The software used in this innovation is available for commercial licensing. Please contact Karina Edmonds of the California Institute of Technology at (626) 395-2322. Refer to NPO-42900.
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Protecting Against Faults In JPL Spacecraft
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Overview
The document discusses fault protection strategies for spacecraft developed by NASA's Jet Propulsion Laboratory (JPL), focusing on the importance of ensuring spacecraft functionality and safety during missions. It outlines the responsibilities of both ground operations and the spacecraft itself in monitoring system health and executing fault recovery actions.
Fault protection is categorized into two main applications: Subsystem Internal Fault Protection (SIFP), which addresses localized subsystem issues, and System Fault Protection (SFP), which monitors and manages faults that could impact the entire spacecraft. The document emphasizes the need for fault protection to prioritize critical spacecraft functionality, minimize disruptions to operations, and simplify ground recovery responses.
Key fault protection strategies include autonomous monitoring of component health, power allocation, and environmental conditions. The document highlights the implementation of functional redundancy and preprogrammed automated responses to address anomalies, thereby enhancing mission integrity. Common requirements across JPL spacecraft include safeguarding command and data processing systems, maintaining communication links, and ensuring safe temperature levels.
Specific fault protection mechanisms are detailed, such as the "Under-Voltage" response, which is crucial for recovering from system-wide power losses. This response allows the spacecraft to shed non-essential loads and isolate defective devices to maintain essential hardware functionality. The document also describes the general-purpose "Safe Mode" response algorithm, which configures the spacecraft to a lower power state to facilitate diagnosis of complex faults.
The document addresses health and safety concerns related to deep space missions, including the effects of extreme temperatures and human error in command sequences. It notes that human-induced errors can lead to significant faults, such as communication failures or power overloads, which can jeopardize mission success.
Additionally, the document discusses the challenges posed by communication lag times in deep space, which can hinder timely fault recovery. It emphasizes the need for robust fault protection systems that can autonomously respond to critical situations before ground teams can intervene.
Overall, the document serves as a comprehensive overview of fault protection techniques employed in JPL spacecraft, highlighting the importance of these strategies in ensuring mission success and the safety of spacecraft systems throughout their operational lifetimes.
