Modeling resonance characteristics of the Chang’e-7 lander under the extreme thermal environment of the lunar south pole

The Chang’e-7 (CE-7) mission will deploy the first seismometer near the lunar south pole in 2027. However, the influence of vibrations from the lander under extreme temperature cycles remains unclear, complicating the analysis of noise sources in the seismic records. In this study, we built a finite-element model of the CE-7 lander and computed its resonance characteristics under two modulating operational factors: the rotation of the sun-tracking solar panel and the extreme temperature variation of the lunar south pole. The six lowest-order modes were dominated by the large vertical solar panel with a fundamental (first-order) frequency of 0.76 Hz at 20 °C. Rotating the panel from 0° to 180° changed the natural frequencies by less than 2% and produced no mode crossing; therefore, sun tracking reoriented the motion and had little effect on its frequency. In contrast, temperature exerts a first-order control: with temperature-dependent elastic moduli, the fundamental frequency rose to 0.80 Hz at –180 °C and fell to 0.75 Hz at +80 °C. Once the uncertainty of the homogenized moduli of the panel and its supporting bracket was considered (±30%, upper bound reported for thermally cycled space solar panels), the fundamental mode may drift over 0.64–0.87 Hz. Sensitivity analysis identified the supporting bracket of the solar panel, rather than the panel itself, as the stiffness bottleneck that governs this drift. The resonance band overlapped with the primary seismic observation window (usually <1.0 Hz) used to probe the lunar interior, whereas the mode shapes remained stable. Therefore, the lander resonance is predictable and can be tracked as a temperature-dependent feature. These results establish a preflight baseline for recognizing and filtering lander-induced resonant noise, which is essential for ensuring the fidelity of lunar interior imaging.