关于北斗G2卫星的溯往追终

2022年1月,失效的北斗G2卫星被实践21号卫星从地球静止轨道拖入了坟墓轨道.为了这项捕获任务的安全实施,需要预先确定北斗G2的旋转状态.基于过去10 yr的测光观测数据展示了北斗G2卫星自转的演化过程.根据北斗G2的自转速度和轨道的演化,确认了在过去的10 yr里发生的6次异常事件.据推测, 2012年的小碎片碰撞事件,是随后几年燃油泄漏的导火索. 2017年之后剩余燃油完全释放,再也没有出现转速异常.将2014年太阳能帆板损坏和2016年的解体事件后建立的旋转动力学模型外推1 yr,转轴的标准偏差小于3°,转速标准偏差为0.11°·s^-1,能够有效地满足捕获任务时刻旋转状态的精度要求.

Design and Study on Mechanical and Thermal Properties of the Cryostat for High Sensitivity Terahertz Detection Module

The High Sensitivity Terahertz Detection Module (HSTDM) is one of the scientific payloads of the China Space Station Survey Telescope, which mainly conducts terahertz astronomical observations. The core of the HSTDM is the NbN superconducting tunnel junction (Superconductor - Insulator - Superconductor (SIS)) mixer, operating at the temperature leq 10K, cooled by a space-qualified two-stage pulse tube refrigerator. The cryostat, which can minimize the heat load of the refrigerator, is a key component to realize the 10K refrigeration environment in space, and it needs to adapt to the mechanical vibration during launch. This paper mainly introduces the structural design, mechanical characteristics simulation analysis and actual measurement, and thermal characteristics simulation analysis of this special cryostat. The fundamental frequency of the cryostat is 189.36Hz. The mechanical analysis results demonstrate that the maximum stress of the support structures is lower than the yield stress of the materials. The vibration test results show that the cryostat can adapt to mechanical environments. The cryostat has a heat leakage of 1800mW to the first cold stage and 20.6mW to the second cold stage, both of which are less than the cooling power of the refrigerator. The thermal analysis results show that the thermal design of the cryostat satisfies the thermal insulation requirements. The research results demonstrate that the cryostat design can meet the space application requirements of the HSTDM.