PRECISION POINTING OF IBEX-Lo OBSERVATIONS
PRECISION POINTING OF IBEX-Lo OBSERVATIONS
复制标题
IBEX-Lo 观测的精确指向
DOI：
10.1088/0067-0049/198/2/9
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
D. McComas
中科院分区：
文献类型：
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作者：
M. Hlond;M. Bzowski;E. Möbius;H. Kucharek;D. Heirtzler;N. Schwadron;M. E. O. Neill;G. Clark;G. Crew;S. Fuselier;D. McComas
星际边界探测器（IBEX）上的IBEX- lo仪器发射后的瞄准角是根据IBEX- lo星敏感器的观测结果确定的。对于星际气体流动参数的精确测定，中性气体相机的内径信息是必不可少的。利用航天器姿态控制系统（ACS）的自旋相位信息，对两年IBEX测量期间由星敏感器观测到的恒星位置进行了分析，并与从星表中获得的位置进行了比较。除了星敏感器安装的发射前不确定性之外，没有观察到统计上显著的差异。根据观测到的恒星及其在航天器参照系中的位置，确定了IBEX卫星自转轴的指向，并与ACS获得的指向进行了比较。同样，没有观察到统计学上显著的偏差。我们得出的结论是，在分析IBEX-Lo观测数据以确定中性星际气体流动特性时，不需要系统校正轴视几何形状。姿态知识的不确定性叠加表明，瞬时IBEX-Lo指向被确定在~ 0以内。°1在旋转角度和仰角使用星敏感器或ACS。此外，星敏感器可用于独立确定航天器自转轴。因此，星敏感器的数据可以可靠地用于校正星跟踪器（由ACS使用）在其视场内被明亮物体禁用时的自旋相位。星敏感器还可以在大多数轨道上确定自转轴，从而为星跟踪器提供冗余。
Post-launch boresight of the IBEX-Lo instrument on board the Interstellar Boundary Explorer (IBEX) is determined based on IBEX-Lo Star Sensor observations. Accurate information on the boresight of the neutral gas camera is essential for precise determination of interstellar gas flow parameters. Utilizing spin-phase information from the spacecraft attitude control system (ACS), positions of stars observed by the Star Sensor during two years of IBEX measurements were analyzed and compared with positions obtained from a star catalog. No statistically significant differences were observed beyond those expected from the pre-launch uncertainty in the Star Sensor mounting. Based on the star observations and their positions in the spacecraft reference system, pointing of the IBEX satellite spin axis was determined and compared with the pointing obtained from the ACS. Again, no statistically significant deviations were observed. We conclude that no systematic correction for boresight geometry is needed in the analysis of IBEX-Lo observations to determine neutral interstellar gas flow properties. A stack-up of uncertainties in attitude knowledge shows that the instantaneous IBEX-Lo pointing is determined to within ∼0.°1 in both spin angle and elevation using either the Star Sensor or the ACS. Further, the Star Sensor can be used to independently determine the spacecraft spin axis. Thus, Star Sensor data can be used reliably to correct the spin phase when the Star Tracker (used by the ACS) is disabled by bright objects in its field of view. The Star Sensor can also determine the spin axis during most orbits and thus provides redundancy for the Star Tracker.
麻省理工学院/德克萨斯大学（美国）
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