TRACE

The Transition Region and Coronal Explorer (TRACE) is a NASA small explorer mission designed to examine the three-dimensional magnetic structures which emerge through the Sun's photosphere (the visible surface of the Sun) and define both the geometry and dynamics of the upper solar atmosphere (the transition region and corona). Its primary science objectives are to: (1) follow the evolution of magnetic field structures from the solar interior to the corona; (2) investigate the mechanisms of the heating of the outer solar atmosphere; and, (3) determine the triggers and onset of solar flares and mass ejections. TRACE is a single-instrument, three-axis stabilized spacecraft. The spacecraft attitude control system (ACS) utilizes three magnetic-torquer coils, a digital sun sensor, six coarse sun sensors, a three-axis magnetometer, four reaction wheels, and three two-axis inertial gyros to maintain pointing. In science mode the spacecraft uses an instrument-provided guide telescope as a fine guidance sensor to provide a pointing accuracy of less than 5 arc-seconds. Power is provided to the spacecraft through the use of four panels of Ga-As solar cells with a total area of 2.0 square-meters. The solar array actually produces power of around 220 W, 85 W of which is used each orbit by the spacecraft and 35 W of which is used by the instrument each orbit. The remaining power is used for operational and decontamination heating of the spacecraft and telescope. A 9 A-hour Ni-Cd battery provides energy during time when the spacecraft is in the Earth's shadow. Communications are provided via a 5 W S-band transponder, providing up to 2.25 Mbps downlink data transmission and 2 kbps uplink. Data are transmitted up to six times daily. Data are stored on-board using a solid-state recorder capable of holding up to 300 MB. The command and data handling system uses a 32-bit 80386/80387 processor.

太阳过渡区域和日冕探测器（TRACE）是美国宇航局的一项小型探测器任务，旨在研究从太阳光球（太阳的可见表面）涌现出的三维磁场结构，这些结构界定了上太阳大气（过渡区域和日冕）的几何形态和动力学特性。其主要的科学目标包括：（1）追踪磁场结构从太阳内部到日冕的演变过程；（2）探究外太阳大气加热的机制；（3）确定太阳耀斑和物质抛射的触发和起始。TRACE是一艘单仪器、三轴稳定的航天器。航天器的姿态控制系统（ACS）采用三个磁力矩线圈、一个数字太阳传感器、六个粗略太阳传感器、一个三轴磁力仪、四个反应轮和三个两轴惯性陀螺仪来维持指向。在科学模式下，航天器使用由仪器提供的引导望远镜作为精细引导传感器，以提供小于5角秒的指向精度。航天器的动力通过四块总面积为2.0平方米的Ga-As太阳能电池板提供。太阳能阵列实际上产生的功率约为220瓦，其中航天器在每个轨道上使用85瓦，仪器使用35瓦。剩余的功率用于航天器和望远镜的操作及去污加热。一个9安时镍镉电池在航天器进入地球阴影期间提供能量。通信通过一个5瓦S波段转发器提供，提供高达2.25兆比特每秒的下传数据传输和2千比特的上传。数据每天传输多达六次。数据存储在板上，使用一个能够存储高达300兆字节的固态记录器。指令和数据处理系统使用32位80386/80387处理器。