For all robotic spacecraft, maintaining the health and functionality of spacecraft subsystems and science instruments is an ongoing task, a challenge which must be met throughout the lifetime of every mission. Material stresses in flight caused by solar heating, the cold of deep space, solar radiation bombardment, etc., can degrade the mission or contribute to malfunctions in subsystem components. In addition to these health risks, autonomously running flight software sequences and in‐flight computer coding upgrades periodically sent to the spacecraft can potentially introduce human‐induced faults. As spacecraft design sophistication and complexity increases, fault diagnosis and resolution becomes a more difficult and time‐consuming task for the ground‐based spacecraft operations flight support (SOFS) team, which must collect large volumes of telemetered data from the spacecraft to diagnose failure occurrences. Often this telemetered data contains hundreds of system data products that must be compared to archived historical data and spacecraft design information to determine failure causes and resolution actions. Additionally, those spacecraft missions that experience great Earth–spacecraft distances such as outer planet exploration missions present an additional challenge as the ever‐increasing time delay period between commands sent and received by the spacecraft limits the ability to respond to failure occurrences in a timely manner. Even more critical are “one‐time mission events” where mission objectives must take place at specific times (such as collecting science data while flying by a planet's moon), or when serious, potentially mission‐catastrophic failures occur so quickly that they must be fixed immediately.

    System health management (SHM) is applied by implementing functional redundancy through flight software (FSW), adding redundant hardware, and applying fault protection (FP) techniques which consist of automated response routines containing preprogrammed instructions to respond to failure conditions. This strategy involves autonomous monitoring of component operation to ensure device health, evaluation of internal and external conditions, and monitoring power allocation to spacecraft devices. Thus, mission robustness may be enhanced by implementing FP strategies which will provide a spacecraft system with greater integrity and diagnostic capability.

    While every robotic spacecraft requires some unique mission‐specific FP, there are many requirements that are common to all spacecraft configurations. These consist of protecting command and data processing capabilities, maintaining attitude control of the vehicle, protection against Earth‐communication loss with the spacecraft, ensuring that safe external and internal temperature levels are maintained, and recovery from power overloads or power loss. To accommodate several of these goals, most spacecraft are equipped with a general‐purpose “safe‐mode response routine” that configures the spacecraft to a reduced power state that is power positive, thermally stable, in a communicative state, with a known predictable configuration so that diagnosis of more complex faults can be addressed by the SOFS team (NASA, 1995).

    This chapter gives an overview of the generic application of FP techniques that are implemented into most interplanetary robotic spacecraft designs.


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    Title :

    Robotic Spacecraft Health Management



    Published in:

    Publication date :

    2011-07-15


    Size :

    12 pages




    Type of media :

    Article/Chapter (Book)


    Type of material :

    Electronic Resource


    Language :

    English




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