Forty-five years after the Apollo and Luna missions returned the lunar samples, China's Chang’E-5 (CE-5) mission collected new samples from the mid-latitude region in the northeastern Oceanus Procellarum of the Moon. Our study shows that 95% of CE-5 lunar soil is distributed in the size of 1.40–9.35 μm, while 95% of the soil by mass is distributed in the size of 4.84–432.27 μm. The bulk density, true density, and specific surface area of CE-5 soil are 1.2387 g/cm3, 3.1952 g/cm3, and 0.56 m2/g, respectively. Fragments from CE-5 regolith are classified into igneous clasts (mostly basalt), agglutinate, and glass. A few breccias were also found. The minerals and compositions of CE-5 soils are consistent with mare basalts and can be classified as low-Ti/low-Al/low-K type with lower rare earth element (REE) contents than materials rich in potassium, rare earth element, and phosphorus (KREEP). CE-5 soils have high FeO and low Mg index, which could represent a new class of basalt.

In the Chang'e-3 mission, the Active Particle-induced X-ray Spectrometer (APXS) on the Yutu rover is used to analyze the chemical composition of lunar soil and rock samples. APXS data are only valid are only if the sensor head gets close to the target and integration time lasts long enough. Therefore, working distance and integration time are the dominant factors that affect APXS results. This study confirms the ability of APXS to detect elements and investigates the effects of distance and time on the measurements. We make use of a backup APXS instrument to determine the chemical composition of both powder and bulk samples under the conditions of different working distances and integration times. The results indicate that APXS can detect seven major elements, including Mg, Al, Si, K, Ca, Ti and Fe under the condition that the working distance is less than 30 mm and having an integration time of 30 min. The statistical deviation is smaller than 15%. This demonstrates the instrument's ability to detect major elements in the sample. Our measurements also indicate the increase of integration time could reduce the measurement error of peak area, which is useful for detecting the elements Mg, Al and Si. However, an increase in working distance can result in larger errors in measurement, which significantly affects the detection of the element Mg.

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