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Landsat-7(陆地卫星-7)卫星继续保持了以前Landsat卫星飞行任务所创造的为用户提供地球遥感数据持续25年以上的记录,同时Landsat-7卫星大大提高了辐射测量和几何测量的性能。Landsat-7卫星公用舱的设计充分继承了DMSP/TIROS卫星系列的成功经验,在此基础上加以改进,延长了卫星自主安全运营的时间。本文介绍在传统设计的基础上增加的检错纠错(FDAC)设计功能,阐明FDAC系统方案的确定、技术实现和测试。这一设计的成果使得卫星在轨容错能力大大加强,很可能确保卫星从故障状态下恢复正常运行。Landsat-7卫星的FDAC设计由3个主要检测单元和一个分层结构的纠正措施阵列组成。故障检测的基础就是所谓的冗余管理(REDMN)功能,这一功能连续监测所选定的卫星功能和性能参数,同时管理故障部件的切换,确保航天器工作状态正常和安全。Landsat-7卫星设计中所考虑的第二个关键功能称之为互连监视(ICMON),这一功能利用加权的部件故障和性能的遥测数据来推断共用硬件的数据通道的异常,这些共同数据通道的异常本身按另一种方式表现为多部件故障。ICMON本质是通过切换备选的数据通道来替代REDMN功能,以避免同时切换多个部件。第三个检测功能是额外增加的一种遥测功能,称之为状态监视功能(SMON),SMON增加了对FDAC各功能的可观测性,因而提高了地面应付星上故障事件的重构能力,促使卫星迅速恢复到正常工作状态。各种纠正措施均依赖部件的切换以及备份模式的切换,其中包括新增加一个保持姿态安全和能源安全的太阳指向姿态模式。
The Landsat-7 satellite continues to maintain the record created by previous Landsat missions to provide users with Earth-remote sensing data for more than 25 years, while the Landsat-7 satellite greatly improves the performance of both radiometric and geometrical measurements. The design of the Landsat-7 satellite common module has inherited the successful experience of the DMSP / TIROS satellite series and has been improved on the basis of this to extend the time for satellite autonomous operation. This article introduces the design of the error-correcting-error-correction (FDAC) function based on the traditional design, and illustrates the scheme of FDAC system determination, technology implementation and testing. The result of this design has greatly enhanced the orbital fault tolerance of satellites and is likely to ensure that satellites resume normal operation from a fault condition. The FDAC design of the Landsat-7 satellite consists of three main detection units and a hierarchical array of corrective measures. The basis for fault detection is the so-called Redundancy Management (REDMN) function, which continuously monitors selected satellite functions and performance parameters and manages the switching of faulty components to ensure that the spacecraft is operating normally and safely. The second key feature considered in Landsat-7 satellite design is called Interconnect Monitoring (ICMON), which uses weighted component failures and performance telemetry data to infer abnormalities in data paths shared by hardware, and these common data Abnormal channel itself by another way for the performance of multi-component failure. The essence of ICMON is to replace REDMN functionality by switching alternate data channels to avoid switching multiple components simultaneously. A third telemetry function, called the SMON, adds an additional telemetry function. SMON adds observability to every FDAC function, thereby improving the ability of the ground to reconstruct on-board fault events, Satellites promptly returned to normal working conditions. Various corrections rely on the switching of components and the switching of backup modes, including the addition of a new solar-pointing attitude mode that maintains attitude safety and energy security.