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.
On 3 January 2019, China's Chang'E-4 (CE-4) successfully landed on the eastern floor of Von Kármán crater within the South Pole-Aitken Basin, becoming the first spacecraft in history to land on the Moon's farside. Here, we report the observations made by the Lunar Penetrating Radar (LPR) onboard the Yutu-2 rover during the first two lunar days. We found a signal penetration at the CE-4 landing site that is much greater than that at the CE-3 site. The CE-4 LPR images provide clear information about the structure of the subsurface, which is primarily made of lowloss, highly porous, granular materials with embedded boulders of different sizes; the images also indicate that the top of the mare basal layer should be deeper than 40 m. These results represent the first high-resolution image of a lunar ejecta sequence ever produced and the first direct measurement of its thickness and internal architecture.
Chang’E-4 (CE-4) was the first mission to accomplish the goal of a successful soft landing on the lunar farside. The landing trajectory and the location of the landing site can be effectively reconstructed and determined using series of images obtained during descent when there were no Earth-based radio tracking and the telemetry data. Here we reconstructed the powered descent trajectory of CE-4 using photogrammetrically processed images of the CE-4 landing camera, navigation camera, and terrain data of Chang’E-2. We confirmed that the precise location of the landing site is 177.5991°E, 45.4446°S with an elevation of −5935 m. The landing location was accurately identified with lunar imagery and terrain data with spatial resolutions of 7 m/p, 5 m/p, 1 m/p, 10 cm/p and 5 cm/p. These results will provide geodetic data for the study of lunar control points, high-precision lunar mapping, and subsequent lunar exploration, such as by the Yutu-2 rover.
[1] We report accelerated particles observed by Solar Wind Ion Detectors (SWIDs) on Chang'E-1 spacecraft close to terminator regions of the Moon. As the spacecraft crosses the terminator, a stream of ions with energy of ∼200eV/q are detected. As the spacecraft moves to the anti-subsolar point of the Moon, the energy of these ions increase by 600 ∼ 1500eV. This phenomenon occurs at north/south pole when IMF B y component is dominant and negative/ positive. It is proposed these particles are scattered solar wind protons, accelerated by the convection electric field of the solar wind and E × B drift in the ambipolar electric field at the flank of the lunar wake. This mechanism allows a new portion of solar wind protons to enter the central lunar wake, and provides a possibility to study the property of proton scattering at the dayside of the Moon.
As part of the Tianwen-1 mission, the Zhurong rover successfully touched down in southern Utopia Planitia on 15 May 2021. On the basis of the new sub-metre-resolution images from the High Resolution Imaging Camera on board the Tianwen-1 orbiter, we determined that the Zhurong rover landed at 109.925° E, 25.066° N at an elevation of −4,099.4 m. The landing site is near the highland–lowland boundary1 and multiple suspected shorelines2–7. Under the guidance of the remote sensing survey, the Zhurong rover is travelling south for specific in situ investigation. Supported by the six payloads on board the rover8, its initial key targets are rocks, rocky fields, transverse aeolian ridges and subsurface structures along the path. Extended investigation will aim at troughs and cones in the distance. A better understanding of the formation mechanisms of these targets may shed light on the historical volcanism and water/ice activities within the landing area, as well as the activities of the wind. These results may reveal the characteristics and evolution of the ancient Martian environment and advance the exploration of the habitability of ancient Mars.
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