(Press-News.org) China's lunar exploration project can be divided into three steps: "orbiting", "landing" and "returning". At present, the first two have been completed, and the third step, "return", will be achieved by the CE-5, which is the first sample return satellite of China and is expected to drill at a depth of no less than 2 m and bring back about 2 kg of scientific samples. In June 2017, the landing region of CE-5 lunar probe was selected as the Rümker region, which is located in the northern Oceanus Procellarum on the lunar near side and has a long volcanic history and complex geological composition.
Because the geographical scope of the region is not clearly defined, the extent determined by the researchers is 35°-45°N and 53°-63°W, which includes Mons Rümker (58.1°W, 40.8°N), Naumann (62.02°W, 35.38°N), Naumann B (60.70°W, 37.46°N), Rümker E (57.14°W, 38.64°N), and Rümker F (57.28°W, 37.26°N), as shown in Figure 1. It is worth noting that the Mons Rümker is a huge and towering shield volcano, which rises about 1000 m above the surrounding area.
To select the specific sampling points within the Rümker region, many scholars have analyzed the topography and geology conditions, lighting and communication conditions, and thermophysical characteristics and so on, but few about features of lunar regolith.
To make up for this deficiency, Zhenzhan WANG, a researcher of the Chinese Academy of Sciences, conducted a study to retrieve the dielectric constant and thickness of lunar regolith based on Chang'e lunar microwave sounder (CELMS) data.
CELMS is the first passive microwave radiometer in the world to sound the lunar surface, which operated at four frequencies: 3, 7.8, 19.35, and 37 GHz, with radiometric resolution of 0.5 K. The brightness temperature (TB) sensed by CELMS is influenced by lunar surface conditions, such as temperature, topography, dielectric constant, lunar regolith thickness, and so on, so these parameters can be retrieved by developing relationships with TB.
Temperature, or more accurately, the effective temperature namely the weighted average temperature within the detected thickness, is the key factor affecting the TB. In practice, effective temperature is calculated by simulated TB for lack of field measurement, so a multi-layer radiation transfer theory is introduced to simulate TB. However, because of the error in the simulated TB, the effective temperature needs to be corrected using the 37 GHz TB, which describes the lunar surface within the top 50 cm and is mainly dependent on the diurnal physical temperature.
In the multi-layer radiation transfer theory, the mare deposit is thought as two types: multi-layer regolith and underlying rock, and assuming that the temperature and dielectric constant in each layer are uniform. The radiation of the lunar surface can be simulated by calculating the emission and reflection of energy in each layer.
The inversion of dielectric constant and thickness of regolith is mainly based on the least square method to find an optimal solution to minimize the sum of squares of the difference between the simulated TB and the measured TB. The inversion of regolith thickness uses the results of the dielectric constant inversion in the previous step. The regolith thickness distribution in the study area is shown in Figure 2.
It can be seen from Figure 2 that the northwest of the study area has the largest regolith thickness, greater than 6m. In addition, the thickness of most areas is uniform and does not exceed 4 m. The Rümker E region shows the shallowest regolith thickness due to the impact effect. Considering the safety and operability of landing and sampling, the northwest with thick regolith is recommended, while the Rümker E should be eluded.
In addition, to reduce the effect of diurnal physical temperature on TB and highlight the features of lunar regolith, the normalized coefficient of diurnal TB was introduced. The coefficient can not only show the temperature difference between day and night, but also represent the dielectric characteristics and thickness of regolith to a certain extent, so it can play a role in verifying the inversion results.
The study provide further support for selecting sampling sites of CE-5 satellite in terms of the thickness distribution of regolith. On the other hand, the research also have important scientific significance for the depth mining and application of CELMS data.
INFORMATION:
This research was funded by the National Natural Science Foundation of China (Grant No. 41771405).
See the article: Wang X, Wang Z, Jiang J, Zhang D. 2021. Research on microwave radiation features and lunar regolith parameters inversion of the Rümker region. Science China Earth Sciences, 64(6): 1005-1014, https://doi.org/10.1007/s11430-020-9739-2
The change from early years services into formal educational settings has long been considered an integral transition point for young people. Now research from Flinders University now asks, "Is service integration actually important to the children?"
A recent paper, published in Children's Geographies, led by Flinders University PhD Dr Jennifer Fane, who is now based at Capilano University in Canada, actually seems to have little impact on children's experiences of this transition.
The Australian Government has supported the Integrated Early Years Services since 2005, following what is considered best practice policy for supporting children and families. It is considered to constitute services that are connected ...
Tantalising evidence has been uncovered for a mysterious population of "free-floating" planets, planets that may be alone in deep space, unbound to any host star. The results include four new discoveries that are consistent with planets of similar masses to Earth, published today in Monthly Notices of the Royal Astronomical Society.
The study, led by Iain McDonald of the University of Manchester, UK, (now based at the Open University, UK) used data obtained in 2016 during the K2 mission phase of NASA's Kepler Space Telescope. During this two-month campaign, Kepler monitored a crowded field of millions ...
Hannah Enders and Dr. Florian Hennicke describe the precise anatomy of these structures of the poplar mushroom in the Journal of Fungi of 19 May 2021.
An edible wild mushroom
One of the organisms attacked by the fungus Cyclocybe parasitica is the Tawa tree (Beilschmiedia tawa), which is relevant to the timber industry in New Zealand. Cyclocybe parasitica is widespread in the Pacific region and has long been known to the Maori, the indigenous people of New Zealand, under the name "Tawaka" as an edible wild mushroom.
Biology student Hannah Elders, supervised by Florian Hennicke at ...
A research collaboration based in Kumamoto University, Japan has discovered that muscles and the resident stem cells (satellite cells) responsible for muscle regeneration retain memory of their location in the body. This positional memory was found to be based on the expression pattern of the homeobox (Hox) gene cluster, which is responsible for shaping the body during fetal life. These findings are expected to provide clues to elucidate the pathogenesis of muscle diseases such as muscular dystrophy, in which the position of muscle vulnerability varies depending on the type of muscle, and to help develop regenerative ...
Overview:
A research team from the Department of Electrical and Electronic Information Engineering at Toyohashi University of Technology developed a chlorine (Cl) substituted Na3SbS4 solid electrolyte for use in all-solid-state sodium (Na) ion batteries. Compared to the sample without a Cl substitution, the ionic conductivity of the Na3SbS4 solid electrolyte where sulfur (S) was partially substituted with Cl improved by up to three times. The team also demonstrated that the Cl-substituted Na3SbS4 has a crystal structure framework that allows Na ions to move easier ...
The Mid-infrared lasers (MIR) with high peak power and high repetition rate operating in the range of 2.7~3 μm have important application in laser surgery and optical parametric oscillator (OPO).
A recent study conducted by SUN Dunlu's research group at the Hefei Institutes of Physical Science(HFIPS) of the Chinese Academy of Sciences (CAS) achieved high power, high efficiency and quasi-continuous mid-infrared laser in the free running and langasite [La3 Ga5 SiO14 (LGS)] Q-switched modes by using the Er3+ ions-doped YAP crystals as laser gain medium.
Based on their previous research work on laser, the researchers further improved the laser performance of Er:YAP laser crystal by laser-diode (LD) side-pumping method, a Er:YAP crystal ...
Sleep problems are common in the general population with up to half of Singaporean adults reporting insufficient or unsatisfying sleep. Sleep quality tends to worsen with age and poor sleep is a modifiable risk factor for multiple disorders, including cardiovascular disease and cognitive impairment.
Currently, insomnia is treated with either medication or psychological interventions. However, even frontline treatments such as cognitive-behavioural therapy have limitations - up to 40% of patients do not get relief from their insomnia symptoms after undergoing ...
In 2016, researchers from the EDDyLab - Evolution & Diversity Dynamics Lab - at the University of Liège (Belgium) proposed a new definition of the geological boundary between the Devonian and Carboniferous periods (359 million years). This new definition has been tested by hundreds of researchers around the world and the results are now compiled in a special issue of the journal Palaeodiversity & Palaeoenvironments.
Geological time is divided into periods (Cambrian, Carboniferous, Jurassic, etc.), together covering the 4.6 billion year history of the Earth. The many climatic, environmental and biological changes that have punctuated this history are recorded in the rock layers, forming an incredibly rich archive of the Earth's past. "The study of these successive ...
Scientists from Tohoku University and the University of Maryland have pinpointed the strong magnetic field of the early sun as the reason behind the radial variation of rock and metal in rocky planets' cores. This magnetic field, which pulled small iron grains inward, explains Mercury's big iron core and why Mars has so little iron in its core.
The details of their research were published in the journal Progress in Earth and Planetary Science on July 5, 2021.
Planets have iron cores surrounded by a rocky shell, mostly made up of mantle and a thin skin of crust. The four inner planets of our Solar System, Mercury, Venus, Earth, and Mars have their own distinctive size and density. These ...
Recently, a research team led by Prof. KONG Lingtao at the Hefei Institutes of Physical Science (HFIPS) of the Chinese Academy of Sciences (CAS) has prepared a type of hollow amorphous Co/C composites to activate hydrogen peroxide (H2O2) to generate singlet oxygen, achieving selective elimination of oxytetracycline (OTC) in complicated water matrices. The relevant results was published in Chemical Engineering Journal.
OTC is the most common tetracycline antibiotic in the field of animal husbandry. It can be detected in water, soil and other areas which features ...
