Dusty Mafic Rocks Along the Path of Chang'E‐4 Rover: Initial Analysis of the Image Cubes of the Onboard Visible and Near‐Infrared Imaging Spectrometer.

The Yutu‐2 rover of Chang'E‐4 encountered four special rocks along its path. The onboard Visible and Near‐infrared Imaging Spectrometer (VNIS) collected their spectral data at close range. In this work, we focus on the visible/near‐infrared image cubes captured by the VNIS. Simple classification was performed using the K‐means algorithm based on the 750/900 nm spectral ratios to highlight the surface material variations. In the case of narrow measurements of phase angle, the classification results were not significantly affected by viewing geometry. Varying degrees of dust coverage on the rock surfaces were revealed, which may be attributed to ejecta deposition and dust electrostatic levitation. The spectral shapes of the less dust‐covered surfaces indicated that these rocks are dominated by mafic materials, suggesting they may not originate from the lunar upper crust. The influence of dust coverage on spectral measurement of rocks was also confirmed, which significantly attenuates the absorption depths. Plain Language Summary: The Chang'E‐4 (CE‐4) mission is the first probe to successfully land on the lunar farside. The rover of CE‐4 mission, Yutu‐2, has come across four curious rocks during its exploration. To reveal their compositions, Yutu‐2 rover conducted close investigations and captured their spectral images using the onboard Visible and Near‐infrared Imaging Spectrometer instrument (VNIS). We analyzed these data and found an interesting phenomenon that these rock surfaces are partly covered by lunar dust. Dust coverage obscures the information from the rocks themselves, making it difficult to decipher the rock compositions if not carefully handled. Fortunately, benefiting from the spatial insight provided by the VNIS, we analyzed the areas with less dust coverage on rock surfaces and determined that these rocks are likely dominated by mafic materials, suggesting that they may not originate from the lunar upper crust. Key Points: The spectral variations of the rock surfaces are revealed using the visible/near‐infrared image cubes collected by the Chang'E‐4 (CE‐4) roverThe four rocks encountered by the CE‐4 rover may be all dominated by mafic materials but with different degrees of dust coverageThe absorption depths of the rock surface spectra in the field of view are significantly attenuated as a result of dust coverage [ABSTRACT FROM AUTHOR]