The Algerian Space Agency has been active in the field of microsatellite engineering for more than 15 years and has successfully developed microsatellites under several know-how transfer technology programs, six to date. This paper presents the flight results and lessons learned from the attitude determination and control system (ADCS) flown on the ALSAT-2B satellite, an Earth observation microsatellite, by analysing the behaviour of the satellite from the initial attitude acquisition through the coarse pointing mode then the nominal mode, where the payload is first tested, and finally the orbit control mode. The spacecraft was launched on 26 September 2016 and placed into a 670km Sun-synchronous orbit with a solar local time at an ascending node of 22:15. The ADCS performance presented here mainly focuses on the launch and early operation results. ALSAT-2B includes four reaction wheels in a pyramidal configuration, three gyros, three Sun sensors, three magneto-torquers, one magnetometer, and one star tracker for agile and accurate attitude control. In addition, a propulsion system based on four 1N hydrazine thrusters is also used on board the microsatellite. The main new development in this platform compared with previous ones of the same type is the fusion of the star tracker and measurements by the three gyroscopes into one gyrostellar estimator that was implemented for the first time on ALSAT-2B, and the pyramidal configuration of the wheels, aiming to increase the angular momentum. The results obtained from the early launch operations for different ADCS modes are very encouraging and fulfil all the requirements set during design and testing. Currently, the satellite has accomplished its fourth year in orbit and is still operational and producing high-quality images.

中文翻译：

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来自 ALSAT-2B 姿态确定和控制系统的在轨结果

阿尔及利亚航天局活跃于微型卫星工程领域已超过 15 年，迄今已在多个专有技术转让技术计划下成功开发了微型卫星，其中有六个。本文通过分析卫星从初始姿态获取到粗定位模式的行为，介绍了在地球观测微型卫星 ALSAT-2B 卫星上飞行的姿态确定和控制系统 (ADCS) 的飞行结果和经验教训。标称模式，首先测试有效载荷，最后是轨道控制模式。该航天器于 2016 年 9 月 26 日发射并进入 670 公里太阳同步轨道，太阳当地时间升交点 22:15。这里介绍的ADCS性能主要集中在发射和早期运行结果。ALSAT-2B 包括四个金字塔形配置的反作用轮、三个陀螺仪、三个太阳传感器、三个磁扭矩仪、一个磁力计和一个用于灵活和准确姿态控制的星跟踪器。此外，微型卫星上还使用了基于四个 1N 肼推进器的推进系统。与之前的同类型平台相比，该平台的主要新发展是将星跟踪器和三个陀螺仪的测量结果融合为一个陀螺估计器，这是在 ALSAT-2B 上首次实现的，以及金字塔结构的轮子，旨在增加角动量。从不同 ADCS 模式的早期发射操作中获得的结果非常令人鼓舞，并且满足了设计和测试期间设定的所有要求。现在，