1. Penumbra lunar eclipse observations reveal anomalous thermal performance of Lunakhod 2 reflectors
- Author
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Xian-lin Wu, Tian-quan Gao, Cai-shi Zhang, Hong-chao Zhao, Li-xiang Zhou, Hsienchi Yeh, and Ming Li
- Subjects
Lunar eclipse ,Penumbra ,Physics::Space Physics ,Thermal ,Astrophysics::Solar and Stellar Astrophysics ,Physics::Optics ,General Physics and Astronomy ,Astronomy ,Astrophysics::Earth and Planetary Astrophysics ,Geology ,Physics::Geophysics - 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.
- Published
- 2022