Lunar Weathering Research Articles

Research on the evaluation method of lunar soil disturbance based on the fitting of Gaussian surface

It is crucial to maintain the layer sequence information on in situ lunar soil during the lunar soil sampling. In this paper, a discrete element model for direct push sampling of the lunar weathering layer is established, and the relationship between the perturbation rate of the lunar soil layer sequence information and the sampling depth is obtained. A quantitative evaluation method of the perturbation rate of the structural information on the lunar soil layer sequence based on the Gaussian curvature is proposed by reconstructing the center-of-mass point cloud model of the marked layer lunar soil particles in MATLAB. The proposed method can accurately describe the perturbation rate of lunar soil layer sequence information and can analyze the degree of lunar soil disturbance according to the displacement of the sampling tube and mechanical parameters in real-time inversion during the sampling process. When the sampling depth is 40 mm, the minimum and maximum perturbation rates of sampling along the penetration direction of the machine are 5.261 % and 27.649 %, respectively. The perturbation rate shows a trend of first decreasing and then increasing. The method proposed in this study could effectively solve the problem that the disturbance of lunar soil bedding information was difficult to evaluate in the sampling process of lunar regolith.

Optimized design of high-efficiency lunar soil sampling tube structure based on stress–strain law

Understanding the influence of the sampling apparatus on in-situ lunar soil lamination information during the sampling process of the direct push-through lunar weathering layer is of great importance. This paper develops a discrete element model for direct push-through lunar weathering layer sampling using the CUG-1A simulated lunar soil developed by the China University of Geosciences as a simulation object and determines the stress–strain law of the inner wall of a sampling tube. A method for optimizing the inner wall structure of a sampling tube based on the stress–strain law is proposed. The structural disturbance of the marker layer and the lunar soil disturbance rate evaluation function are used to assess the degree of disturbance of the laminar information during the sampling process. The results show that the proposed method can effectively reduce the structural disturbance of the lunar soil in-situ laminar information. In addition, it can also optimize the structural information disturbance of the marker layer. The proposed method can decrease the simulated lunar soil disturbance rate from 0.31 to 0.251 and effectively reduce the penetration force load by 15–20% in the direct push-through sampling process.

Atmospheric circulation and variability of meteorological elements in near-shore Black Sea region

Effect of solar radiation and atmospheric circulation on variability of air temperature, atmospheric pressure, and rainfall in near-shore Black Sea region was examined. The action of the latitudinal position of trajectory cyclonic and anticyclonic movements and their times of occurrence in seasonal variability of meteorological elements was established. Three factor action on cyclonican and anticyclonic movement latitudinal position was determined. This is air temperature (year cycle), North-Atlantic oscillation, and lunar weather tides. Seasonal times of occurrence of cyclon and anticyclone, movements of southerly and northerly trajectories, and variability of atmospheric pressure and rainfall in near-shore Black Sea region was estimated.

嫦娥四号着陆点原位高光谱的太空风化研究

Without atmosphere, the lunar surface is gradually evolved into lunar soil by the space weathering. The space weathering generates lunar soil and matures it. This progress changes the morphological structure and the spectral characteristics. Thus the spectral characteristics of lunar soil contains information about the space weathering of the moon's surface. Lunar soil maturity is an important indicator to describe the degree of the space weathering. Using hyperspectral data to produce the submicroscopic metallic iron (SMFe) and to obtain lunar maturity is an important method for studying the space weathering. Since the in situ detection data is not disturbed, the results obtained are relatively more accurate and reliable. Therefore, the Chang'e-4 (CE-4) Yutu-2 rover was equipped with a detection instrument that directly obtained the in situ hyperspectral data (450-2395 nm) of the lunar surface, which provided a good opportunity for studying the lunar weathering. Two spectral data near the landing site of the CE-4 lander were selected, using the Hapke model and the spectral angle matching method, SMFe content was produced. The maturity of the lunar soil near the landing site of the CE-4 was further inferred based on the Morris model and FeO content. The results show that the lunar soil's maturity is 11.5, indicating that it may be immature lunar soil.

Incremental laser space weathering of Allende reveals non-lunar like space weathering effects

We report findings from a series of laser-simulated space weathering experiments on Allende, a CV3 carbonaceous chondrite. The purpose of these experiments is to understand how spectra of anhydrous C-complex asteroids might vary as a function of micrometeorite bombardment. Four 0.5-gram aliquots of powdered, unpacked Allende meteorite were incrementally laser weathered with 30mJ pulses while under vacuum. Radiative transfer modeling of the spectra and Scanning Transmission Electron Microscope (STEM) analyses of the samples show lunar-like similarities and differences in response to laser-simulated space weathering. For instance, laser weathered Allende exhibited lunar-like spectral changes. The overall spectra from visible to near infrared (Vis-NIR) redden and darken, and characteristic absorption bands weaken as a function of laser exposure. Unlike lunar weathering, however, the continuum slope between 450–550nm does not vary monotonically with laser irradiation. Initially, spectra in this region redden with laser irradiation; then, the visible continua become less red and eventually spectrally bluer. STEM analyses of less mature samples confirm submicroscopic iron metal (SMFe) and micron sized sulfides. More mature samples reveal increased dispersal of Fe-Ni sulfides by the laser, which we infer to be the cause for the non-lunar-like changes in spectral behavior. Spectra of laser weathered Allende are a reasonable match to T- or possibly K-type asteroids; though the spectral match with a parent body is not exact. The key take away is, laser weathered Allende looks spectrally different (i.e., darker, and redder or bluer depending on the wavelength region) than its unweathered spectrum. Consequently, connecting meteorites to asteroids using unweathered spectra of meteorites would result in a different parent body than one matched on the basis of weathered spectra. Further, spectra for these laser weathering experiments may provide an explanation for inconsistencies observed in both laboratory (e.g., Hiroi et al., 2003, 2001; Lazzarin et al., 2006; Moroz et al., 2004, 1996; Shingareva et al., 2004) and telescopic data (Lazzarin et al., 2006; Marchi et al., 2006; Nesvorný et al., 2005).

Lunar weather measurements at three Apollo sites 1969–1976

AbstractThe first lunar weather stations, matchbox‐sized, 270 g Apollo Dust Detector Experiments about 100 cm above the surface of the Moon near Apollo 12, 14, and 15 landing sites, measured dust accretion, charged particle radiation, and temperature changes—three environmental factors proved during Apollo to affect technical systems deployed on the Moon. Degradation of seven horizontal solar cells was measured every lunar daytime from 1969 to 1976. The anomalously intense August 1972 solar particle event (SPE) degraded three covered cells by less than 1%, while two cells desensitized by intense preirradiation showed no measurable effects. Although independent studies estimated the long‐term fluence bombarding the cells was less than half that of the August SPE, long‐term gradual degradation of five covered cells (normalized to 2000 days) was an order of magnitude greater, between 4% and 10%. If the long‐term effects were totally caused by dust, with articulated caveats including simulated (maria) Minnesota Lunar Simulant‐1 dust particles with diameters 20 to 38 µm, this provides the first direct measured long‐term net accretion of dust with an upper limit of order 100 µg cm−2 yr−1, equivalent to a layer 1 mm thick in 1000 years, but it may be significantly less. Two bare cells were abruptly degraded by 7% during the August SPE, however long‐term they measured additional damage of 29% and 24%, indicating a long‐neglected suite of low‐energy radiation, posing risks for bare materials exposed on the surface of the Moon.

Microprobe studies of space weathering effects in extraterrestrial dust grains

A new microprobing procedure is used to characterize both the physical and chemical surface properties of individual grains on a microscale. In this procedure the same sub-micrometre sized area of a given grain is successively analysed with a high voltage electron microscope, an Auger microprobe and a field emission scanning electron microscope. This analytical technique has been applied to study lunar weathering effects and to tentatively infer the irradiation history of a Nerich fraction of the Orgueil meteorite.

“Christmas Storm” known to Christian Fishers in Japan

A small group of Kirisitan (Christian) has miraculously survived in Japan despite the severe oppression in Tokugawa Period. While the majority of Japanese used a lunar calendar, only these Kirisitan fishers knew Gregorian Calendar introduced by Portugese missionaries. During the oppression time their christianity has transformed into a polytheistic religion. Even so they have kept and used their calendar until today for their services with a day's delay from the Gregorian Calendar.Through this solar calendar, they have experienced that on their Christmas Eve, 23 rd of December, heavy storms often began, followed by calm days on 26th and 27th. These storms are confirmed by Fig. 1 to be the winter monsoon from Siberia and the calm days to be the result of the weakening of the Siberian High (Fig. 2).A problem arises whether these Kirisitans have discovered this “Christmas Storm” by themselves or they have learnt it from Portugese missionaries four hundred years ago. For it is possible that the Portugese missionaries knew something about the Portugese weather on these days of which equivalent is known in Germany as Wheinachtstauwetter (Christmas Bad Weather).Such a oversea spread of weather knowledge seems to be possible through a case study on the west coat of South America, where fishers know Viento de San Juan (Wind of St. John) etc which are not supported by the local meteorogical observations. In this case a spread from Spain seems to be probable.On the other hand, some of Japanese fishers have used a lunar calendar even until today with several knowledges on lunar singularities such as “8 th's Storm” etc. Against my working hypothesis that such knowledges reflect local weather differences, the distributions of lunar weather knowledges are almost uniform throughout Japan except “Daishiko Storm” and “Daishiko Calm” on 23rd of XI Month (Fig. 3 and 4).This uniformity may indicate that a spreading played more important role in the aquirment of weather knowledges than discovery. Since some similarities in lunar weather knowledges are found in Korea and Taiwan a spread from the mainland of China is possible.By such considerations a spread of “Christmas Storm” from Portugal still remains a possible guess. Informations from Portugal are most welcomed.

Micromorphology and Surface Characteristics of Lunar Dust and Breccia

Although nothing of direct biologic interest was observed in the sample studied, small shaped glass particles and glazed pits resemble objects which elsewhere have been described as fossils. These features, although nonbiological, do bear on processes of lunar weathering and outgassing. The glazed pits are impact features. Fusion of their surfaces released gases. Electron microscopy of the glasses, pits, and angular microfractured mineral grains indicates a prevalence of destructive weathering processes-thermal expansion and contraction, abrasion by by-passing particles, and, of course, impact. ous at room temperature.