During its first two lunar day measurements, the visible and near‐infrared spectrometer on board the Yutu‐2 Rover of the Chang'E‐4 mission acquired six in situ reflectance spectra from the floor of Von Kármán crater within the South Pole‐Aitken basin. A spectral lookup table search has shown that the regolith at the landing site contains 56–72% plagioclase, 9–28% orthopyroxene, 4–19% clinopyroxene, and 2–12% olivine, in relative abundance, in agreement with the results from Kaguya Multiband Imager mineral mapping. A mineral composition analysis using measurements made by the Moon Mineralogy Mapper and the Multiband Imager has shown that the surface materials of the landing site may have been ejected from the nearby Finsen crater. This result is also supported by principal component analysis which shows a strong correlation between the compositions of the landing area and Finsen crater.

The chemical compositions of relatively young mare lava flows have implications for the late volcanism on the Moon. Here we report the composition of soil along the rim of a 450-m diameter fresh crater at the Chang′e-3 (CE-3) landing site, investigated by the Yutu rover with in situ APXS (Active Particle-induced X-ray Spectrometer) and VNIS (Visible and Near-infrared Imaging Spectrometer) measurements. Results indicate that this region's composition differs from other mare sample-return sites and is a new type of mare basalt not previously sampled, but consistent with remote sensing. The CE-3 regolith derived from olivine-normative basaltic rocks with high FeO/(FeO+MgO). Deconvolution of the VNIS data indicates abundant high-Ca ferropyroxene (augite and pigeonite) plus Fe-rich olivine. We infer from the regolith composition that the basaltic source rocks formed during late-stage magma-ocean differentiation when dense ferropyroxene-ilmenite cumulates sank and mixed with deeper, relatively ferroan olivine and orthopyroxene in a hybridized mantle source.

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A graphical method for evaluating the Langmuir favorable adsorption is proposed in this work. The conditional Langmuir constant (K L N ), a new parameter related to the Langmuir equilibrium constant (K L ), can be used to predict the shapes of Langmuir favorable adsorption isotherms. On the dimensionless Langmuir isotherm diagram, all the Langmuir favorable adsorptions (0 < R L < 1) are further divided into three subgroups: favorable adsorption, very favorable adsorption, and highly favorable or pseudoirreversible adsorption, with two critical Langmuir constants (K L N1 and K L N2) as the demarcation point. The feasibility of the method is demonstrated by analyzing 14 adsorption systems. The graphical method is effective and intuitional, and can be used for the favorable evaluation of any Langmuir isotherms. This method shows the advantage that the parameter K L N does not depend on the initial adsorbate concentration (c o ) over R L method.