中国物理B ›› 2022, Vol. 31 ›› Issue (5): 50602-050602.doi: 10.1088/1674-1056/ac3068

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Penumbra lunar eclipse observations reveal anomalous thermal performance of Lunakhod 2 reflectors

Tian-Quan Gao(高添泉), Cai-Shi Zhang(张才士), Hong-Chao Zhao(赵宏超), Li-Xiang Zhou(周立祥), Xian-Lin Wu(吴先霖), Hsienchi Yeh(叶贤基), and Ming Li(李明)   

  1. MOE Key Laboratory of TianQin Mission, TianQin Research Center for Gravitational Physics & School of Physics and Astronomy, Frontiers Science Center for TianQin, CNSA Research Center for Gravitational Waves, Sun Yat-sen University (Zhuhai Campus), Zhuhai 519082, China
  • 收稿日期:2021-08-26 修回日期:2021-10-08 出版日期:2022-05-14 发布日期:2022-04-18
  • 通讯作者: Ming Li,E-mail:liming73@mail.sysu.edu.cn E-mail:liming73@mail.sysu.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No.12033009).

Penumbra lunar eclipse observations reveal anomalous thermal performance of Lunakhod 2 reflectors

Tian-Quan Gao(高添泉), Cai-Shi Zhang(张才士), Hong-Chao Zhao(赵宏超), Li-Xiang Zhou(周立祥), Xian-Lin Wu(吴先霖), Hsienchi Yeh(叶贤基), and Ming Li(李明)   

  1. MOE Key Laboratory of TianQin Mission, TianQin Research Center for Gravitational Physics & School of Physics and Astronomy, Frontiers Science Center for TianQin, CNSA Research Center for Gravitational Waves, Sun Yat-sen University (Zhuhai Campus), Zhuhai 519082, China
  • Received:2021-08-26 Revised:2021-10-08 Online:2022-05-14 Published:2022-04-18
  • Contact: Ming Li,E-mail:liming73@mail.sysu.edu.cn E-mail:liming73@mail.sysu.edu.cn
  • About author:2021-10-18
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No.12033009).

摘要: As the signal reflected by the corner-cube reflector arrays is very weak and easily submerged during the full moon, we analyze the influence of the thermal effect of corner-cube reflector arrays on the intensity of lunar laser ranging echo. Laser ranging measurements during the penumbra lunar eclipse verify suspected thermal deformation in the Lunakhod 2 reflectors. Signal levels vary over two orders of magnitude as the penumbra eclipse progresses. This can be explained by the change in the dihedral angle of the corner-cube reflectors caused by the temperature. The results show that when the dihedral angle errors reach 1'', the energy is reduced by 100 times compared with the ideal corner-cube reflector. In the experiment, our findings suggest that when the corner-cube reflector arrays enter the penumbra of the earth, the effective echo signal level which reaches 0.18 photons/s far exceeds the historical level of the full moon. However, 11 minutes after the penumbra lunar eclipse, the effective echo rate of Lunakhod 2 will drop two orders of magnitude. The mechanism can explain the acute signal deficit observed at full moon.

关键词: lunar laser ranging, corner-cube reflector arrays, dihedral angle errors, penumbra lunar eclipse

Abstract: As the signal reflected by the corner-cube reflector arrays is very weak and easily submerged during the full moon, we analyze the influence of the thermal effect of corner-cube reflector arrays on the intensity of lunar laser ranging echo. Laser ranging measurements during the penumbra lunar eclipse verify suspected thermal deformation in the Lunakhod 2 reflectors. Signal levels vary over two orders of magnitude as the penumbra eclipse progresses. This can be explained by the change in the dihedral angle of the corner-cube reflectors caused by the temperature. The results show that when the dihedral angle errors reach 1'', the energy is reduced by 100 times compared with the ideal corner-cube reflector. In the experiment, our findings suggest that when the corner-cube reflector arrays enter the penumbra of the earth, the effective echo signal level which reaches 0.18 photons/s far exceeds the historical level of the full moon. However, 11 minutes after the penumbra lunar eclipse, the effective echo rate of Lunakhod 2 will drop two orders of magnitude. The mechanism can explain the acute signal deficit observed at full moon.

Key words: lunar laser ranging, corner-cube reflector arrays, dihedral angle errors, penumbra lunar eclipse

中图分类号:  (Measurements common to several branches of physics and astronomy)

  • 06.30.-k
07.07.Df (Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing) 07.60.-j (Optical instruments and equipment)