FACSAT-2纳米卫星的过早再入：轨道衰减及其归因于第25太阳活动周极大期
Premature re-entry of the FACSAT-2 nanosatellite: orbital decay and attribution to the maximum of solar cycle 25
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- Observatorio Astronómico Nacional, Universidad Nacional de Colombia（哥伦比亚国家天文台，哥伦比亚国立大学）
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中文总结 AI 辅助
针对FACSAT-2纳米卫星提前926天再入，通过TLE和大气模型反演弹道系数，归因于第25太阳活动周极大期导致的高阻力，并讨论对后续任务设计的影响。
中文摘要 AI 辅助
FACSAT-2 Chiribiquete是哥伦比亚空军的第二颗卫星，也是南美洲首个专用于温室气体监测的纳米卫星任务，于2025年10月27日再入大气层，距其部署到太阳同步轨道仅926天，而官方宣称的设计寿命至少为五年，估计轨道寿命为十五年。轨道演化基于NORAD ID 56205的TLE（双行根数）历元构建。我们利用其3696个轨道根数、来自OMNI2数据库的太阳和地磁指数，以及沿轨道采样的NRLMSISE-00密度，重建了其衰减过程。通过反演阻力，得到弹道系数为72.3 kg/m²（统计误差6%，系统误差20%），等效有效面积为0.047 m²，与官方公布的几何形状一致。利用该系数，模型复现轨迹的均方根误差为7.4 km，且仅以2023-2024年数据校准后，再入时间的样本外预测误差为28天。任务期间F10.7指数平均为170.8 sfu，而基于2019年官方预测的环境场景为139 sfu，后者使轨道寿命延长1.52倍；两颗同箭发射的CubeSat分别得到1.50和1.57倍，这仅作为跨物体的交叉验证，而非独立证据。若施加地磁宁静条件，则再入时间缩短102天，占总缩短量的22%，且对采用的阈值高度敏感；对149次磁暴进行叠加历元分析，强磁暴事件的中位阻力增强为1.92倍。我们讨论了这些结果对FACSAT-3设计以及任务预期寿命公开传达的影响。
英文摘要
FACSAT-2 Chiribiquete, the second satellite of the Colombian Aerospace Force and the first South American nanosatellite mission dedicated to greenhouse gases, re-entered on 27 October 2025, 926 days after its deployment into a Sun-synchronous orbit, against a declared service life of at least five years and an estimated orbital lifetime of fifteen. The orbital evolution was built from the epochs of the TLEs (two-line elements) of NORAD ID 56205. We reconstruct its decay using its 3696 orbital elements, the solar and geomagnetic indices from the OMNI2 database, and NRLMSISE-00 densities sampled along the orbit. Inverting the drag yields a ballistic coefficient of 72.3 kg/m2 (6% statistical, 20% systematic), equivalent to an effective area of 0.047 m2, consistent with the declared geometry. With it, the model reproduces the trajectory with a root-mean-square error of 7.4 km and, calibrated on 2023-2024 alone, the re-entry with a 28-day out-of-sample error. F10.7 averaged 170.8 sfu over the mission, against the 139 sfu of the environmental scenario derived from the official 2019 forecast, which lengthens the orbital lifetime by x1.52; two co-launched CubeSats give x1.50 and x1.57, a consistency check across objects rather than independent evidence. Imposing quiet geomagnetic conditions returns 102 days, 22% of the shortening, with strong sensitivity to the adopted threshold; a superposed-epoch analysis over 149 storms gives a median drag enhancement of x1.92 for the intense events. We discuss the consequences for the design of FACSAT-3 and for the public communication of a mission's expected lifetime.
