This paper examines the influence of gravity on the bulk responses of a granular solid. The loading scenarios in this study include confined compression, rod penetration into a granular medium and discharging through ...This paper examines the influence of gravity on the bulk responses of a granular solid. The loading scenarios in this study include confined compression, rod penetration into a granular medium and discharging through an orifice. Similar loading and flow conditions are likely to be encountered in the stress and deformation regimes that regoliths are subjected to in extraterrestrial exploration activities including in situ resource utilisation processes. Both spherical and non-spherical particles were studied using the discrete element method （DEM）. Whilst DEM is increasingly used to model granular solids, careful validations of the simulation outcomes are rather rare. Thus in addition to exploring the effect of gravity, this paper also compares DEM simulations with experiments under terrestrial condition to verify whether DEM can produce satisfactory predictions. The terrestrial experiments were conducted with great care and simulated closely using DEM. The key mechanical and geometrical properties for the particles were measured in laboratory tests for use in the DEM simulations. A series of DEM computations were then performed under reduced gravity to simulate these experiments under extraterrestrial environment. It was found that gravity has no noticeable effect on the force transmission in the confined compression case; the loading gradient in the rod penetration is linearly proportional to the gravity; the mass flow rate in silo discharge is proportional to square root of the gravity and the angle of repose increases with reducing gravity. These findings are in agreement with expectation and existing scientific evidence.展开更多
The Angstrom-Prescott formula is commonly used in climatological calculation methods of solar radiation simulation. Fitting the coefficients is carried out using linear regression and in recent years it has been found...The Angstrom-Prescott formula is commonly used in climatological calculation methods of solar radiation simulation. Fitting the coefficients is carried out using linear regression and in recent years it has been found that these coefifcients have obvious spatial variability. A common solution is to divide the study area into several subregions and ift the coefifcients one by one. Here, we use ground observation data for sunshine hours and solar radiation from 1961 to 2010. Adopting extraterrestrial radiation as the initial value, Angstrom-Prescott coefifcients are obtained by Geographically Weighted Regression at a national scale. The surfaces of solar radiation are obtained on the basis of the surfaces of sunshine hours interpolated by high accuracy surface modeling and astronomical radiation;results from spatial y nonstationary and error comparison tests show that Angstrom-Prescott coefifcients have signiifcant spatial nonstationarity. Compared to existing research methods, the method presented here achieves a better simulation effect.展开更多
Solar radiation is often shielded by terrain relief, especially in mountainous areas, before reaching the surface of the Earth. The objective of this paper is to study the spatial structures of the shielded astronomic...Solar radiation is often shielded by terrain relief, especially in mountainous areas, before reaching the surface of the Earth. The objective of this paper is to study the spatial structures of the shielded astronomical solar radiation(SASR) and the possible sunshine duration(PSD) over the Loess Plateau. To this end, we chose six test areas representing different landforms over the Loess Plateau and the software package of Matlab was used as the main computing platform. In each test area, 5-m-resolution digital elevation model established from 1:10,000 scale topographic maps was used to compute the corresponding slope, SASR and PSD. Then, we defined the concepts of the slope-mean SASR spectrum and the slope-mean PSD spectrum, and proposed a method to extract them from the computed slope, SASR and PSD over rectangular analysis windows. Using this method, we found both spectrums in a year or in a season for each of the four seasons in the six test areas. Each spectrum was found only when the area of the corresponding rectangular analysis window was greater than the corresponding stable area of the spectrum. The values of the two spectrums decreased when the slope increased.Furthermore, the values of the stable areas of the spectrums in a year or in a season were positively correlated with the variable coefficients of the slope or the profile curvature. The values of the stable areas of the two spectrums in a year or in a season may represent the minimum value of test areas for corresponding future research on the spatial structures of the SASR or PSD. All the findings herein suggest that the spatial structures of the PSD and the SASR are caused by the interactions between solar radiation and terrain relief and that the method for extracting either spectrum is effective for detecting their spatial structures. This study may deepen our understanding of the spatial structure of solar radiation and help us further explore the distribution of solar energy in mountainous regions.展开更多
The construction of extraterrestrial bases has become a new goal in the active exploration of deep space.Among the construction techniques,in situ resource-based construction is one of the most promising because of it...The construction of extraterrestrial bases has become a new goal in the active exploration of deep space.Among the construction techniques,in situ resource-based construction is one of the most promising because of its good sustainability and acceptable economic cost,triggering the development of various types of extraterrestrial construction materials.A comprehensive survey and comparison of materials from the perspective of performance was conducted to provide suggestions for material selection and optimization.Thirteen types of typical construction materials are discussed in terms of their reliability and applicability in extreme extraterrestrial environment.Mechanical,thermal and optical,and radiation-shielding properties are considered.The influencing factors and optimization methods for these properties are analyzed.From the perspective of material properties,the existing challenges lie in the comprehensive,long-term,and real characterization of regolith-based construction materials.Correspondingly,the suggested future directions include the application of high-throughput characterization methods,accelerated durability tests,and conducting extraterrestrial experiments.展开更多
A selection of evidence, including a carbon isotopic excursion, iridium anomaly, fullerenes (C 60 and C 70 ) with trapped noble gases, microspherules and shocked quartz, is discussed in this paper. All the ev...A selection of evidence, including a carbon isotopic excursion, iridium anomaly, fullerenes (C 60 and C 70 ) with trapped noble gases, microspherules and shocked quartz, is discussed in this paper. All the evidence in hand favors the hypothesis that the PTB event was probably related to an extraterrestrial cause, and the impact would lead to great physical change, including large volcanic eruptions on the earth's surface. The ET markers for the CTB event could be considered only as an example, and cannot be taken as a unique standard of an ET event.展开更多
Numerous iron cosmic micro-spherules have been discovered from Mesoproterozoic strata including the Changzhougou Formation （1.8 Ga） and the Dahongyu Formation （1.6 Ga） of the Ming Tombs district, Beijing. There ar...Numerous iron cosmic micro-spherules have been discovered from Mesoproterozoic strata including the Changzhougou Formation （1.8 Ga） and the Dahongyu Formation （1.6 Ga） of the Ming Tombs district, Beijing. There are 1 to 30 grains of cosmic spherules per 2 kg of a sandstone sample taken from the bottom of a coarse sandstone bed of the Changzhougou Formation and 56 grains per 3.69 kg of a rock sample from silicified carbonate rocks of the Dahongyu Formation. The surface textures of cosmic spherules analyzed by means of the secondary electron imagery are identical with those reported from references either domestic or abroad. So far the geo-ages of 1.8 Ga and 1.6 Ga of cosmic spherules from the Changzhougou and Dahongyu formations might be older than those reported in the world. Table 1 gives the electron probe analysis data of cosmic spherules for 30 spherule grains and 44 testing points as follows （%）： FeO, 80-95; Cr2O3; 0-9.56; NiO, 0-0.78; CoO, 0-0.46; indicating that the Cr2O3 content is higher and FeO content lower in the Changzhougou Formation than in the Dahongyu Formation. The helium isotopic data of cosmic spherules as well as their host rocks vary greatly between the Changzhougou and the Dahongyu formations as shown in Table 2. The data of cosmic spherules of the Changzhougou Formation vs the Dahongyu Formation are 57.5/1.23 in ^3He/^4He （10^-8）; and 55.54/809.60 in ^4He （10^-6cm^3STP/g）; those of coarse sandstone of the Changzhougou Formation vs silicified carbonate of the Dahongyu Formation are 3.39/2.59 in ^3He/^4He （10^-8） and 4.56/2.34 in ^3He （10^-6cm^3STP/g）. The ratio of analytic data of helium isotopes are different for cosmic spherules and their host rocks; for example, the ^3He/^4He （10^-8） values are 16.96 and 0.48, and the ^4He （10^-6 cm^3STP/g） are 12.18 and 345.98 for the Changzhougou and Dahongyu formations respectively. It was reported that the world＇s oldest micrometeorites had been found in the Meso-Proterozoic Satakunta Formation, Finland. Howeve展开更多
How and where did life on Earth originate？ To date, various environments have been proposed as plausible sites for the origin of life. However, discussions have focused on a limited stage of chemical evolution, or em...How and where did life on Earth originate？ To date, various environments have been proposed as plausible sites for the origin of life. However, discussions have focused on a limited stage of chemical evolution, or emergence of a specific chemical function of proto-biological systems. It remains unclear what geochemical situations could drive all the stages of chemical evolution, ranging from condensation of simple inorganic compounds to the emergence of self-sustaining systems that were evolvable into modern biological ones. In this review, we summarize reported experimental and theoretical findings for prebiotic chemistry relevant to this topic, including availability of biologically essential elements（N and P） on the Hadean Earth, abiotic synthesis of life＇s building blocks（amino acids, peptides, ribose, nucleobases, fatty acids, nucleotides, and oligonucleotides）, their polymerizations to bio-macromolecules（peptides and oligonucleotides）, and emergence of biological functions of replication and compartmentalization. It is indicated from the overviews that completion of the chemical evolution requires at least eight reaction conditions of（1） reductive gas phase,（2） alkaline pH,（3） freezing temperature,（4）fresh water,（5） dry/dry-wet cycle,（6） coupling with high energy reactions,（7） heating-cooling cycle in water, and（8） extraterrestrial input of life＇s building blocks and reactive nutrients. The necessity of these mutually exclusive conditions clearly indicates that life＇s origin did not occur at a single setting; rather, it required highly diverse and dynamic environments that were connected with each other to allow intratransportation of reaction products and reactants through fluid circulation. Future experimental research that mimics the conditions of the proposed model are expected to provide further constraints on the processes and mechanisms for the origin of life.展开更多
Whether the platinum group elements (PGE) can be taken as the indicators of extraterrestrial materials is a very important and interesting scientific problem. It is discussed on the basis of systematic investigation a...Whether the platinum group elements (PGE) can be taken as the indicators of extraterrestrial materials is a very important and interesting scientific problem. It is discussed on the basis of systematic investigation and study of a great amount of related literature. The following conclusions can be obtained: (ⅰ) extraterrestrial impact event can cause the PGE anomaly; conversely, the PGE anomaly may not represent the existence of extraterrestrial impact event, because the PGE anomaly can be caused by many terrestrial events (e.g. volcanic activity); (ⅱ) the PGE anomaly, especially the global PGE anomaly can inspire us to think it from extraterrestrial event, but it may not be as useful as previously thought as unambiguous identifiers of large extraterrestrial impact event in the earth’s history.展开更多
New samples returned by China Chang’e-5(CE-5)mission offer an opportunity for studying the lunar geologic longevity,space weathering,and regolith evolution.The age determination of the CE-5 samples was among the firs...New samples returned by China Chang’e-5(CE-5)mission offer an opportunity for studying the lunar geologic longevity,space weathering,and regolith evolution.The age determination of the CE-5 samples was among the first scientific questions to be answered.However,the precious samples,most in the micrometer size range,challenge many traditional analyses on large single crystals of zircon developed for massive bulk samples.Here,we developed a non-destructive rapid screening of individual zirconium-containing particle for isotope geochronology based on a Micro X-ray fluorescence analysis(μXRF).The selected particles were verified via scanning electron microscopy(SEM),3D X-ray microscopy(XRM),and focused ion beam scanning electron microscopy(FIB-SEM)techniques,which showed that zirconium-bearing minerals with several microns were precisely positioned and readily suitable for site-specific isotopic dating by second ion mass spectrometry(SIMS).Such protocol could be also appli-cable in non-destructively screening other types of particles for different scientific purposes.We there-fore proposed a correlative workflow for comprehensively studying the CE-5 lunar samples from single particles on nanometer to atomic scales.Linking various microscopic and spectromicroscopic instru-ments together,this workflow consists of six steps:(1)single-particle selection with non-destructive μXRF technique,(2)2D/3D morphological and structural characterization with a correlative submicron 3D XRM and nanoscale resolution FIB-SEM imaging methods,(3)SEM analysis of the surface morphology and chemistry of the selected particle,(4)a series of microscopic and microbeam analyses(e.g.,SEM,electron probe microanalysis,and SIMS)on the cross-section of the selected particle to obtain structural,mineralogical,chemical,and isotopic features from the micron to nanometer scale,(5)advanced 2D/3D characterization and site-specific sample preparation of thin foil/tip specimens on a microregion of inter-est in the selected particle with FIB-SEM techniqu展开更多
The monthly extraterrestrial solar radiations (ESR) have been simulated separately for all the months of the year. The subtropical location and distribution of mountains and their height determine the spatial distribu...The monthly extraterrestrial solar radiations (ESR) have been simulated separately for all the months of the year. The subtropical location and distribution of mountains and their height determine the spatial distribution and amount of ESR in Pakistan. The mountains, piedmonts, enclosed valleys and plains show distinct diversity of ESR values. The assessment acknowledged that countries like Pakistan with ever increasing demand of energy receive sufficient amount of ESR that could be linked with solar irradiance where development of solar energy has great potential. The simulation was done with the help of ArcGIS based on distributed modeling.展开更多
For the measurement of atmospheric NO2 vertical column density (VCD), Kitt Peak Solar Flux Atlas can be substituted as an extraterrestrial solar radiation. Compared with differential analysis method, the Taylor expans...For the measurement of atmospheric NO2 vertical column density (VCD), Kitt Peak Solar Flux Atlas can be substituted as an extraterrestrial solar radiation. Compared with differential analysis method, the Taylor expansion of integrated transfer equation underestimates the VCD. This underestimation is as large as 35% when the amount of NO2 is 1 × 1017 cm?2 and observation is conducted with an air mass factor of 10. Even when the VCD is 2 × 1016 cm?2 and the air mass factor is 4, the relative error of the retrieved VCD is still no less than 3%. If the observation is restricted under the small air mass factor condition (≤ 4), with Kitt Peak Solar spectrum as an extraterrestrial solar radiation, only an atmospheric layer of 2 km thick from ground can be studied, which will make the absorption too weak to be detected by normal instruments. The VCD in winter Tokyo area was observed and analyzed by differential method, which shows a good precision even when the absorption is as low as 3%. The largest average VCD was about 1.3 × 1017 cm-2, and the lowest was about 1.3 × 1016 cm?2. The trend of its variation was almost the same as the ground level observation by Saltzman reagent method. Key words Vertical column density (VCD) - Extraterrestrial solar radiation - NO2 - Atmospheric contamination展开更多
The Quaternary infilling of a circular structure located in Bajada del Diablo,Chubut Province,Argentina has been proposed as a crater strewn field in previous studies.Here we report the finding of about 65 microspheru...The Quaternary infilling of a circular structure located in Bajada del Diablo,Chubut Province,Argentina has been proposed as a crater strewn field in previous studies.Here we report the finding of about 65 microspherules collected in a trench excavated in the center of the structure.The majority of handpicked specimens are single,but some of them exhibit compound forms.The single specimens are spherical with a mean size of 137 nm,whereas the more complex samples show peduncles and drop shapes.Dendritic crystal growth is recognized in the internal structure of some broken microspherules.Preliminary chemical composition from the surface and center of microspherules was determined by energy dispersive spectrometry employing EDS.Quantitative EMPA and XRD analysis indicate that the microspherules are mainly composed of Fe and O with magnetite,Fe0with subordinate wiistite.Following consideration of possible anthropogenic and volcanic origins,these spherulites are ascribed to an extraterrestrial input.An accumulation rate of 47 microspherules per m2/yr is estimated for the studied sediments.This value is two orders of magnitude higher than the reference flux for cosmic dust estimated for the last 1 Ma in the Transantarctic Mountains.The microspherules might have been generated as a byproduct of asteroid entry in the atmosphere.展开更多
The existing data on the confirmed extraterrestrial impacts and geomagnetic reversals are examined. Differential rotation of the inner core of the Earth relative to the rest of the planet has been observed through sei...The existing data on the confirmed extraterrestrial impacts and geomagnetic reversals are examined. Differential rotation of the inner core of the Earth relative to the rest of the planet has been observed through seismic records. Differential rotation between the inner and outer core is thought to be related to the geomagnetic field of the Earth. Extraterrestrial impacts with the surface of the Earth have been shown to cause changes in this differential rotation. It is shown in this paper that there is a strong correlation between the dates of major impacts and geomagnetic reversals. This strongly supports the possibility of major extraterrestrial impacts being one of the causes of geomagnetic reversals as has been suggested previously.展开更多
The Drake formula is a statistical method of forecasting the possible number N of technically evolved extraterrestrial and galactic civilizations able to communicate with the human species. It is based on seven differ...The Drake formula is a statistical method of forecasting the possible number N of technically evolved extraterrestrial and galactic civilizations able to communicate with the human species. It is based on seven different factors that can be grouped into factors of type A, f<sub>A</sub> (“Astrophysicist”) and type B, f<sub>B</sub> (“Astrobiological”). The quantitative analysis of these factors at the time of the presentation of the formula was subjective and highly variable for both factors f<sub>A</sub> and f<sub>B</sub>. Current scientifical and technological development has made it possible to refine the quantitative estimates of the f<sub>A</sub> group whose definition is now less uncertain. In group f<sub>A</sub> the parameter n<sub>e</sub> is understood as the number of planets capable of sustaining life. By means of n<sub>e</sub> Drake defines this possibility exclusively from the geometric point of view. In particular, the planet’s orbit must be included in the circumstellar space in which the planetary temperature allows the presence of liquid water. This is not enough because, for liquid (and gaseous) water to be present on the planet’s surface, it is also essential that the planet has a magnetic field of adequate intensity to shield the flow of charged particles coming from its star (solar wind). The solar wind is able to break up and disperse the liquid and gaseous water molecules and any organic molecules in times much shorter than theoretically necessary for the formation of life and above all, except for singularities, than necessary for evolution to arrive at intelligent life. Here the planetary magnetic field parameter n<sub>m</sub> is introduced into the Drake formula and its statistical probability of existence is discussed.展开更多
The discovery of ubiquitous habitable extrasolar planets,combined with revolutionary advances in instrumentation and observational capabilities,has ushered in a renaissance in the search for extraterrestrial intellige...The discovery of ubiquitous habitable extrasolar planets,combined with revolutionary advances in instrumentation and observational capabilities,has ushered in a renaissance in the search for extraterrestrial intelligence(SETI).Large scale SETI activities are now underway at numerous international facilities.The Five-hundred-meter Aperture Spherical radio Telescope(FAST)is the largest single-aperture radio telescope in the world,and is well positioned to conduct sensitive searches for radio emission indicative of exo-intelligence.SETI is one of the five key science goals specified in the original FAST project plan.A collaboration with the Breakthrough Listen Initiative was initiated in 2016 with a joint statement signed both by Dr.Jun Yan,the then director of National Astronomical Observatories,Chinese Academy of Sciences(NAOC),and Dr.Peter Worden,Chairman of the Breakthrough Prize Foundation.In this paper,we highlight some of the unique features of FAST that will allow for novel SETI observations.We identify and describe three different signal types indicative of a technological source,namely,narrow band,wide-band artificially dispersed and modulated signals.Here,we propose observations with FAST to achieve sensitivities never before explored.For nearby exoplanets,such as TESS targets,FAST will be sensitive to an EIRP of 1.9×1011 W,well within the reach of current human technology.For the Andromeda Galaxy,FAST will be able to detect any Kardashev type II or more advanced civilization there.展开更多
It is possible, the question on the existence of extraterrestrial life will be answered not as a result of its search for in other worlds removed by distances of dozens of parsecs but on the surface of Venus, i.e., of...It is possible, the question on the existence of extraterrestrial life will be answered not as a result of its search for in other worlds removed by distances of dozens of parsecs but on the surface of Venus, i.e., of the nearest planet of the Solar system. The search for “habitable zones” in extrasolar planetary systems is based on the postulate on “normal” physical conditions, i.e., the pressure, temperature, and maybe atmospheric composition similar to those on Earth. But could not such an approach be a kind of “terrestrial chauvinism”? Considering the conditions on Venus as a possible analogue of physical conditions on low-orbiting exoplanets of the “super-Earths” type, a new analysis of Venusian surface panoramas’ details has been made. These images were produced by the VENERA landers in 1975 and 1982. A few relatively large objects were found with size ranging from a decimeter to half meter and with unusual morphology. The objects were observed in some images, but were absent in the other or altered their shape. The article presents the obtained results and analyzes the evidence of reality of these objects.展开更多
Geologic marks related to extraterrestrial impact events, such as impact split gravels, impact brecciate layers, impact dikes, microirghizites, microtektites, especially meteoritic residues, were discovered on the bou...Geologic marks related to extraterrestrial impact events, such as impact split gravels, impact brecciate layers, impact dikes, microirghizites, microtektites, especially meteoritic residues, were discovered on the boundary between Sinian/Cambrian at Tianmenshan of Western Hunan, which may possibly demonstrate that an extraterrestrial impact event has ever occurred there on the S/C boundary.展开更多
A method to compute the daily, monthly and yearly extra terrestrial solar irradiation (S_(ot), S_(otm), S_(oty)) on tilted surfaces for arbitrary latitude is determined. The systematic distributional charts of S_(ot),...A method to compute the daily, monthly and yearly extra terrestrial solar irradiation (S_(ot), S_(otm), S_(oty)) on tilted surfaces for arbitrary latitude is determined. The systematic distributional charts of S_(ot), S_(otm) and S_(oty) on a global scale are given for the first time. Some specific rules are discovered: (ⅰ) The latitudinal variation curves of the slope irradiation for different azimuths converge polewards. (ⅱ) At the North (South) Pole the different azimuth's values of the irradiation for a given slope and time period are identical. (ⅲ) At the equinoctial dates, the S_(ot) on the east (or west) vertical surface does not vary with latitude (except poles). (ⅳ) If some latitude range in the polar regions is all in the polar day at a certain date, the S_(ot) on the east (or west) vertical surface in the date is also not varying with latitude in the range. (ⅴ) The yearly irradiation S_(oty) on the east (or west) vertical surface maintains the same value for any latitude.(ⅵ) The extraterrestrial irradiation in the Southern and Northern Hemispheres is in a reverse-approximate symmetry.展开更多
We develop a new calibration method in lab by measuring the absolute spectral irradiance responsivity of Sun photometer sun channel. The absolute power responsivity of Sun photometer is obtained when a white laser dou...We develop a new calibration method in lab by measuring the absolute spectral irradiance responsivity of Sun photometer sun channel. The absolute power responsivity of Sun photometer is obtained when a white laser double monochromator system serve as a source, and a standard transfer detector calibrated against cryogenic absolute radiometer is assembled to measure the absolute power of laser beam. The effective area of aperture is measured through laser raster scanning method, and the relative spectral irradiance responsivity of the corresponding channel is obtained by using tungsten-halogen lamps double monoehromator system. On the basis of the above results, the top of the atmosphere responsive constants V0 （500, 675, and 870 nm） are obtained by integration with extraterrestrial solar spectral irradiance data. Comparing the calibration results with that of CIMEL, France in November 2011, the relative differences are 4.38%, 2.23%, and 2.45%, respectively. The calibration uncertainty reaches to 2.048×10^-2, which shows a remarkable consistency with the Langley plot method. Further, our scheme can overcome the limits of space and atmospheric conditions which are only available at a high-altitude calibration site in particular date. The advantages lie in not only shortening the experiment period but also being of high precision. This new scheme definitely plays an important role in supporting the current and future sun photometry calibration activities which are significant to earth observation.展开更多
Three advances are proposed as a pathway to the cataclysmic event of our first encounter with intelligent extraterrestrial beings. First, discovery of very large numbers of extraterrestrial planets, “exoplanets” (po...Three advances are proposed as a pathway to the cataclysmic event of our first encounter with intelligent extraterrestrial beings. First, discovery of very large numbers of extraterrestrial planets, “exoplanets” (possibly as many as10<sup>23</sup> in our Universe);second, introduction of electronic components into the human body evolving into a cybernetic and biological “cyborg,” a model for an extraterrestrial being Cyborgs might allow advanced civilizations to endure hundreds of thousands of years. Third, the recent development of high-frequency gravitational wave (HFGW) detectors, the communication means of choice for an advanced cyborg civilization since they are not easily absorbed like electromagnetic radiation. Six HFGW detectors are presented for application to our first encounter with intelligent extraterrestrial beings. Numerical estimates are made for the failure of extraterrestrial civilizations such that no two exist at the same time (Fermi’s Paradox). It is concluded that there might remain at least ≈1.48 × 10<sup>8</sup> Worlds intercommunicating with HFGWs at any one time in any one region of our Universe. The predicted form of extraterrestrial beings is by means of animaginary, but based upon comprehensively documented and detailed projection of the evolution of “Earthling” homosapiens, to become “cyborgs.” It is proposed that such long-living cyborg forms of intelligent beings would be encountered by us. The first cataclysmic encounter with them is expected to be interception of their interstellar communications. The predicted frequency of intercepted messages under one set of assumptions is at least 1500 per day. After decoding the intercepted messages, keys may be found to improve vastly the present and future quality of life for us earthlings. Advanced beings might utilize direct brain-to-brain communication and it is concluded that research into brain-to-brain communication and HFGW detection are encouraged.展开更多
文摘This paper examines the influence of gravity on the bulk responses of a granular solid. The loading scenarios in this study include confined compression, rod penetration into a granular medium and discharging through an orifice. Similar loading and flow conditions are likely to be encountered in the stress and deformation regimes that regoliths are subjected to in extraterrestrial exploration activities including in situ resource utilisation processes. Both spherical and non-spherical particles were studied using the discrete element method （DEM）. Whilst DEM is increasingly used to model granular solids, careful validations of the simulation outcomes are rather rare. Thus in addition to exploring the effect of gravity, this paper also compares DEM simulations with experiments under terrestrial condition to verify whether DEM can produce satisfactory predictions. The terrestrial experiments were conducted with great care and simulated closely using DEM. The key mechanical and geometrical properties for the particles were measured in laboratory tests for use in the DEM simulations. A series of DEM computations were then performed under reduced gravity to simulate these experiments under extraterrestrial environment. It was found that gravity has no noticeable effect on the force transmission in the confined compression case; the loading gradient in the rod penetration is linearly proportional to the gravity; the mass flow rate in silo discharge is proportional to square root of the gravity and the angle of repose increases with reducing gravity. These findings are in agreement with expectation and existing scientific evidence.
基金National Key Technologies R&D Program of China(2013BAC03B05)National High-tech R&D Program of China(2013AA122003)
文摘The Angstrom-Prescott formula is commonly used in climatological calculation methods of solar radiation simulation. Fitting the coefficients is carried out using linear regression and in recent years it has been found that these coefifcients have obvious spatial variability. A common solution is to divide the study area into several subregions and ift the coefifcients one by one. Here, we use ground observation data for sunshine hours and solar radiation from 1961 to 2010. Adopting extraterrestrial radiation as the initial value, Angstrom-Prescott coefifcients are obtained by Geographically Weighted Regression at a national scale. The surfaces of solar radiation are obtained on the basis of the surfaces of sunshine hours interpolated by high accuracy surface modeling and astronomical radiation;results from spatial y nonstationary and error comparison tests show that Angstrom-Prescott coefifcients have signiifcant spatial nonstationarity. Compared to existing research methods, the method presented here achieves a better simulation effect.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41771423, 41930102, 41601408 and 41491339)the industry-university-research cooperation project for the social development of Fujian province, China (grant number 2018Y0054)
文摘Solar radiation is often shielded by terrain relief, especially in mountainous areas, before reaching the surface of the Earth. The objective of this paper is to study the spatial structures of the shielded astronomical solar radiation(SASR) and the possible sunshine duration(PSD) over the Loess Plateau. To this end, we chose six test areas representing different landforms over the Loess Plateau and the software package of Matlab was used as the main computing platform. In each test area, 5-m-resolution digital elevation model established from 1:10,000 scale topographic maps was used to compute the corresponding slope, SASR and PSD. Then, we defined the concepts of the slope-mean SASR spectrum and the slope-mean PSD spectrum, and proposed a method to extract them from the computed slope, SASR and PSD over rectangular analysis windows. Using this method, we found both spectrums in a year or in a season for each of the four seasons in the six test areas. Each spectrum was found only when the area of the corresponding rectangular analysis window was greater than the corresponding stable area of the spectrum. The values of the two spectrums decreased when the slope increased.Furthermore, the values of the stable areas of the spectrums in a year or in a season were positively correlated with the variable coefficients of the slope or the profile curvature. The values of the stable areas of the two spectrums in a year or in a season may represent the minimum value of test areas for corresponding future research on the spatial structures of the SASR or PSD. All the findings herein suggest that the spatial structures of the PSD and the SASR are caused by the interactions between solar radiation and terrain relief and that the method for extracting either spectrum is effective for detecting their spatial structures. This study may deepen our understanding of the spatial structure of solar radiation and help us further explore the distribution of solar energy in mountainous regions.
基金supported by the National Key Research and Development Program of China(2023YFB3711300 and 2021YFF0500300)the Strategic Research and Consulting Project of the Chinese Academy of Engineering(2023-XZ-90 and 2023-JB-09-10)the National Key Research and Development Program of China(2021YFF0500300).
文摘The construction of extraterrestrial bases has become a new goal in the active exploration of deep space.Among the construction techniques,in situ resource-based construction is one of the most promising because of its good sustainability and acceptable economic cost,triggering the development of various types of extraterrestrial construction materials.A comprehensive survey and comparison of materials from the perspective of performance was conducted to provide suggestions for material selection and optimization.Thirteen types of typical construction materials are discussed in terms of their reliability and applicability in extreme extraterrestrial environment.Mechanical,thermal and optical,and radiation-shielding properties are considered.The influencing factors and optimization methods for these properties are analyzed.From the perspective of material properties,the existing challenges lie in the comprehensive,long-term,and real characterization of regolith-based construction materials.Correspondingly,the suggested future directions include the application of high-throughput characterization methods,accelerated durability tests,and conducting extraterrestrial experiments.
文摘A selection of evidence, including a carbon isotopic excursion, iridium anomaly, fullerenes (C 60 and C 70 ) with trapped noble gases, microspherules and shocked quartz, is discussed in this paper. All the evidence in hand favors the hypothesis that the PTB event was probably related to an extraterrestrial cause, and the impact would lead to great physical change, including large volcanic eruptions on the earth's surface. The ET markers for the CTB event could be considered only as an example, and cannot be taken as a unique standard of an ET event.
基金This work was granted by National Nature Science Foundation of China （Nos. 49772121, 40172044 and 40672082）.
文摘Numerous iron cosmic micro-spherules have been discovered from Mesoproterozoic strata including the Changzhougou Formation （1.8 Ga） and the Dahongyu Formation （1.6 Ga） of the Ming Tombs district, Beijing. There are 1 to 30 grains of cosmic spherules per 2 kg of a sandstone sample taken from the bottom of a coarse sandstone bed of the Changzhougou Formation and 56 grains per 3.69 kg of a rock sample from silicified carbonate rocks of the Dahongyu Formation. The surface textures of cosmic spherules analyzed by means of the secondary electron imagery are identical with those reported from references either domestic or abroad. So far the geo-ages of 1.8 Ga and 1.6 Ga of cosmic spherules from the Changzhougou and Dahongyu formations might be older than those reported in the world. Table 1 gives the electron probe analysis data of cosmic spherules for 30 spherule grains and 44 testing points as follows （%）： FeO, 80-95; Cr2O3; 0-9.56; NiO, 0-0.78; CoO, 0-0.46; indicating that the Cr2O3 content is higher and FeO content lower in the Changzhougou Formation than in the Dahongyu Formation. The helium isotopic data of cosmic spherules as well as their host rocks vary greatly between the Changzhougou and the Dahongyu formations as shown in Table 2. The data of cosmic spherules of the Changzhougou Formation vs the Dahongyu Formation are 57.5/1.23 in ^3He/^4He （10^-8）; and 55.54/809.60 in ^4He （10^-6cm^3STP/g）; those of coarse sandstone of the Changzhougou Formation vs silicified carbonate of the Dahongyu Formation are 3.39/2.59 in ^3He/^4He （10^-8） and 4.56/2.34 in ^3He （10^-6cm^3STP/g）. The ratio of analytic data of helium isotopes are different for cosmic spherules and their host rocks; for example, the ^3He/^4He （10^-8） values are 16.96 and 0.48, and the ^4He （10^-6 cm^3STP/g） are 12.18 and 345.98 for the Changzhougou and Dahongyu formations respectively. It was reported that the world＇s oldest micrometeorites had been found in the Meso-Proterozoic Satakunta Formation, Finland. Howeve
基金partly supported by JSPS KAKENHI Grant Nos. 26800276 (Grant-in-Aid for Young Scientists (B)), 16H04074 (Grant-in-Aid for Scientific Research (B)), 16K13906 (Grant-in-Aid for Challenging Exploratory Research), and 26106001 (Grant-in-Aid for Scientific Research on Innovative Areas)
文摘How and where did life on Earth originate？ To date, various environments have been proposed as plausible sites for the origin of life. However, discussions have focused on a limited stage of chemical evolution, or emergence of a specific chemical function of proto-biological systems. It remains unclear what geochemical situations could drive all the stages of chemical evolution, ranging from condensation of simple inorganic compounds to the emergence of self-sustaining systems that were evolvable into modern biological ones. In this review, we summarize reported experimental and theoretical findings for prebiotic chemistry relevant to this topic, including availability of biologically essential elements（N and P） on the Hadean Earth, abiotic synthesis of life＇s building blocks（amino acids, peptides, ribose, nucleobases, fatty acids, nucleotides, and oligonucleotides）, their polymerizations to bio-macromolecules（peptides and oligonucleotides）, and emergence of biological functions of replication and compartmentalization. It is indicated from the overviews that completion of the chemical evolution requires at least eight reaction conditions of（1） reductive gas phase,（2） alkaline pH,（3） freezing temperature,（4）fresh water,（5） dry/dry-wet cycle,（6） coupling with high energy reactions,（7） heating-cooling cycle in water, and（8） extraterrestrial input of life＇s building blocks and reactive nutrients. The necessity of these mutually exclusive conditions clearly indicates that life＇s origin did not occur at a single setting; rather, it required highly diverse and dynamic environments that were connected with each other to allow intratransportation of reaction products and reactants through fluid circulation. Future experimental research that mimics the conditions of the proposed model are expected to provide further constraints on the processes and mechanisms for the origin of life.
文摘Whether the platinum group elements (PGE) can be taken as the indicators of extraterrestrial materials is a very important and interesting scientific problem. It is discussed on the basis of systematic investigation and study of a great amount of related literature. The following conclusions can be obtained: (ⅰ) extraterrestrial impact event can cause the PGE anomaly; conversely, the PGE anomaly may not represent the existence of extraterrestrial impact event, because the PGE anomaly can be caused by many terrestrial events (e.g. volcanic activity); (ⅱ) the PGE anomaly, especially the global PGE anomaly can inspire us to think it from extraterrestrial event, but it may not be as useful as previously thought as unambiguous identifiers of large extraterrestrial impact event in the earth’s history.
基金the National Key R&D Program of China(2018YFA0702600)the Key Research program of Chinese Academy of Sciences(ZDBS-SSW-JSC007-13)+1 种基金the institute of Geology and Geophysics,Chinese Academy of Sciences(IGGCAS-202101)the National Natural Science Foundation of China(grants no.41890843,41920104009)。
文摘New samples returned by China Chang’e-5(CE-5)mission offer an opportunity for studying the lunar geologic longevity,space weathering,and regolith evolution.The age determination of the CE-5 samples was among the first scientific questions to be answered.However,the precious samples,most in the micrometer size range,challenge many traditional analyses on large single crystals of zircon developed for massive bulk samples.Here,we developed a non-destructive rapid screening of individual zirconium-containing particle for isotope geochronology based on a Micro X-ray fluorescence analysis(μXRF).The selected particles were verified via scanning electron microscopy(SEM),3D X-ray microscopy(XRM),and focused ion beam scanning electron microscopy(FIB-SEM)techniques,which showed that zirconium-bearing minerals with several microns were precisely positioned and readily suitable for site-specific isotopic dating by second ion mass spectrometry(SIMS).Such protocol could be also appli-cable in non-destructively screening other types of particles for different scientific purposes.We there-fore proposed a correlative workflow for comprehensively studying the CE-5 lunar samples from single particles on nanometer to atomic scales.Linking various microscopic and spectromicroscopic instru-ments together,this workflow consists of six steps:(1)single-particle selection with non-destructive μXRF technique,(2)2D/3D morphological and structural characterization with a correlative submicron 3D XRM and nanoscale resolution FIB-SEM imaging methods,(3)SEM analysis of the surface morphology and chemistry of the selected particle,(4)a series of microscopic and microbeam analyses(e.g.,SEM,electron probe microanalysis,and SIMS)on the cross-section of the selected particle to obtain structural,mineralogical,chemical,and isotopic features from the micron to nanometer scale,(5)advanced 2D/3D characterization and site-specific sample preparation of thin foil/tip specimens on a microregion of inter-est in the selected particle with FIB-SEM techniqu
文摘The monthly extraterrestrial solar radiations (ESR) have been simulated separately for all the months of the year. The subtropical location and distribution of mountains and their height determine the spatial distribution and amount of ESR in Pakistan. The mountains, piedmonts, enclosed valleys and plains show distinct diversity of ESR values. The assessment acknowledged that countries like Pakistan with ever increasing demand of energy receive sufficient amount of ESR that could be linked with solar irradiance where development of solar energy has great potential. The simulation was done with the help of ArcGIS based on distributed modeling.
文摘For the measurement of atmospheric NO2 vertical column density (VCD), Kitt Peak Solar Flux Atlas can be substituted as an extraterrestrial solar radiation. Compared with differential analysis method, the Taylor expansion of integrated transfer equation underestimates the VCD. This underestimation is as large as 35% when the amount of NO2 is 1 × 1017 cm?2 and observation is conducted with an air mass factor of 10. Even when the VCD is 2 × 1016 cm?2 and the air mass factor is 4, the relative error of the retrieved VCD is still no less than 3%. If the observation is restricted under the small air mass factor condition (≤ 4), with Kitt Peak Solar spectrum as an extraterrestrial solar radiation, only an atmospheric layer of 2 km thick from ground can be studied, which will make the absorption too weak to be detected by normal instruments. The VCD in winter Tokyo area was observed and analyzed by differential method, which shows a good precision even when the absorption is as low as 3%. The largest average VCD was about 1.3 × 1017 cm-2, and the lowest was about 1.3 × 1016 cm?2. The trend of its variation was almost the same as the ground level observation by Saltzman reagent method. Key words Vertical column density (VCD) - Extraterrestrial solar radiation - NO2 - Atmospheric contamination
基金carried out under Project UBACyT 20020130100146/14X236PIP 00416/11PICT 2013-1950
文摘The Quaternary infilling of a circular structure located in Bajada del Diablo,Chubut Province,Argentina has been proposed as a crater strewn field in previous studies.Here we report the finding of about 65 microspherules collected in a trench excavated in the center of the structure.The majority of handpicked specimens are single,but some of them exhibit compound forms.The single specimens are spherical with a mean size of 137 nm,whereas the more complex samples show peduncles and drop shapes.Dendritic crystal growth is recognized in the internal structure of some broken microspherules.Preliminary chemical composition from the surface and center of microspherules was determined by energy dispersive spectrometry employing EDS.Quantitative EMPA and XRD analysis indicate that the microspherules are mainly composed of Fe and O with magnetite,Fe0with subordinate wiistite.Following consideration of possible anthropogenic and volcanic origins,these spherulites are ascribed to an extraterrestrial input.An accumulation rate of 47 microspherules per m2/yr is estimated for the studied sediments.This value is two orders of magnitude higher than the reference flux for cosmic dust estimated for the last 1 Ma in the Transantarctic Mountains.The microspherules might have been generated as a byproduct of asteroid entry in the atmosphere.
文摘The existing data on the confirmed extraterrestrial impacts and geomagnetic reversals are examined. Differential rotation of the inner core of the Earth relative to the rest of the planet has been observed through seismic records. Differential rotation between the inner and outer core is thought to be related to the geomagnetic field of the Earth. Extraterrestrial impacts with the surface of the Earth have been shown to cause changes in this differential rotation. It is shown in this paper that there is a strong correlation between the dates of major impacts and geomagnetic reversals. This strongly supports the possibility of major extraterrestrial impacts being one of the causes of geomagnetic reversals as has been suggested previously.
文摘The Drake formula is a statistical method of forecasting the possible number N of technically evolved extraterrestrial and galactic civilizations able to communicate with the human species. It is based on seven different factors that can be grouped into factors of type A, f<sub>A</sub> (“Astrophysicist”) and type B, f<sub>B</sub> (“Astrobiological”). The quantitative analysis of these factors at the time of the presentation of the formula was subjective and highly variable for both factors f<sub>A</sub> and f<sub>B</sub>. Current scientifical and technological development has made it possible to refine the quantitative estimates of the f<sub>A</sub> group whose definition is now less uncertain. In group f<sub>A</sub> the parameter n<sub>e</sub> is understood as the number of planets capable of sustaining life. By means of n<sub>e</sub> Drake defines this possibility exclusively from the geometric point of view. In particular, the planet’s orbit must be included in the circumstellar space in which the planetary temperature allows the presence of liquid water. This is not enough because, for liquid (and gaseous) water to be present on the planet’s surface, it is also essential that the planet has a magnetic field of adequate intensity to shield the flow of charged particles coming from its star (solar wind). The solar wind is able to break up and disperse the liquid and gaseous water molecules and any organic molecules in times much shorter than theoretically necessary for the formation of life and above all, except for singularities, than necessary for evolution to arrive at intelligent life. Here the planetary magnetic field parameter n<sub>m</sub> is introduced into the Drake formula and its statistical probability of existence is discussed.
文摘The discovery of ubiquitous habitable extrasolar planets,combined with revolutionary advances in instrumentation and observational capabilities,has ushered in a renaissance in the search for extraterrestrial intelligence(SETI).Large scale SETI activities are now underway at numerous international facilities.The Five-hundred-meter Aperture Spherical radio Telescope(FAST)is the largest single-aperture radio telescope in the world,and is well positioned to conduct sensitive searches for radio emission indicative of exo-intelligence.SETI is one of the five key science goals specified in the original FAST project plan.A collaboration with the Breakthrough Listen Initiative was initiated in 2016 with a joint statement signed both by Dr.Jun Yan,the then director of National Astronomical Observatories,Chinese Academy of Sciences(NAOC),and Dr.Peter Worden,Chairman of the Breakthrough Prize Foundation.In this paper,we highlight some of the unique features of FAST that will allow for novel SETI observations.We identify and describe three different signal types indicative of a technological source,namely,narrow band,wide-band artificially dispersed and modulated signals.Here,we propose observations with FAST to achieve sensitivities never before explored.For nearby exoplanets,such as TESS targets,FAST will be sensitive to an EIRP of 1.9×1011 W,well within the reach of current human technology.For the Andromeda Galaxy,FAST will be able to detect any Kardashev type II or more advanced civilization there.
文摘It is possible, the question on the existence of extraterrestrial life will be answered not as a result of its search for in other worlds removed by distances of dozens of parsecs but on the surface of Venus, i.e., of the nearest planet of the Solar system. The search for “habitable zones” in extrasolar planetary systems is based on the postulate on “normal” physical conditions, i.e., the pressure, temperature, and maybe atmospheric composition similar to those on Earth. But could not such an approach be a kind of “terrestrial chauvinism”? Considering the conditions on Venus as a possible analogue of physical conditions on low-orbiting exoplanets of the “super-Earths” type, a new analysis of Venusian surface panoramas’ details has been made. These images were produced by the VENERA landers in 1975 and 1982. A few relatively large objects were found with size ranging from a decimeter to half meter and with unusual morphology. The objects were observed in some images, but were absent in the other or altered their shape. The article presents the obtained results and analyzes the evidence of reality of these objects.
基金financially supported by China National Natural Science Foundation(Grant No.40172078).
文摘Geologic marks related to extraterrestrial impact events, such as impact split gravels, impact brecciate layers, impact dikes, microirghizites, microtektites, especially meteoritic residues, were discovered on the boundary between Sinian/Cambrian at Tianmenshan of Western Hunan, which may possibly demonstrate that an extraterrestrial impact event has ever occurred there on the S/C boundary.
文摘A method to compute the daily, monthly and yearly extra terrestrial solar irradiation (S_(ot), S_(otm), S_(oty)) on tilted surfaces for arbitrary latitude is determined. The systematic distributional charts of S_(ot), S_(otm) and S_(oty) on a global scale are given for the first time. Some specific rules are discovered: (ⅰ) The latitudinal variation curves of the slope irradiation for different azimuths converge polewards. (ⅱ) At the North (South) Pole the different azimuth's values of the irradiation for a given slope and time period are identical. (ⅲ) At the equinoctial dates, the S_(ot) on the east (or west) vertical surface does not vary with latitude (except poles). (ⅳ) If some latitude range in the polar regions is all in the polar day at a certain date, the S_(ot) on the east (or west) vertical surface in the date is also not varying with latitude in the range. (ⅴ) The yearly irradiation S_(oty) on the east (or west) vertical surface maintains the same value for any latitude.(ⅵ) The extraterrestrial irradiation in the Southern and Northern Hemispheres is in a reverse-approximate symmetry.
基金supported by the National 973 Project Fund(No.2010CB950801)the National Natural Science Foundation of China(No.61275173)
文摘We develop a new calibration method in lab by measuring the absolute spectral irradiance responsivity of Sun photometer sun channel. The absolute power responsivity of Sun photometer is obtained when a white laser double monochromator system serve as a source, and a standard transfer detector calibrated against cryogenic absolute radiometer is assembled to measure the absolute power of laser beam. The effective area of aperture is measured through laser raster scanning method, and the relative spectral irradiance responsivity of the corresponding channel is obtained by using tungsten-halogen lamps double monoehromator system. On the basis of the above results, the top of the atmosphere responsive constants V0 （500, 675, and 870 nm） are obtained by integration with extraterrestrial solar spectral irradiance data. Comparing the calibration results with that of CIMEL, France in November 2011, the relative differences are 4.38%, 2.23%, and 2.45%, respectively. The calibration uncertainty reaches to 2.048×10^-2, which shows a remarkable consistency with the Langley plot method. Further, our scheme can overcome the limits of space and atmospheric conditions which are only available at a high-altitude calibration site in particular date. The advantages lie in not only shortening the experiment period but also being of high precision. This new scheme definitely plays an important role in supporting the current and future sun photometry calibration activities which are significant to earth observation.
文摘Three advances are proposed as a pathway to the cataclysmic event of our first encounter with intelligent extraterrestrial beings. First, discovery of very large numbers of extraterrestrial planets, “exoplanets” (possibly as many as10<sup>23</sup> in our Universe);second, introduction of electronic components into the human body evolving into a cybernetic and biological “cyborg,” a model for an extraterrestrial being Cyborgs might allow advanced civilizations to endure hundreds of thousands of years. Third, the recent development of high-frequency gravitational wave (HFGW) detectors, the communication means of choice for an advanced cyborg civilization since they are not easily absorbed like electromagnetic radiation. Six HFGW detectors are presented for application to our first encounter with intelligent extraterrestrial beings. Numerical estimates are made for the failure of extraterrestrial civilizations such that no two exist at the same time (Fermi’s Paradox). It is concluded that there might remain at least ≈1.48 × 10<sup>8</sup> Worlds intercommunicating with HFGWs at any one time in any one region of our Universe. The predicted form of extraterrestrial beings is by means of animaginary, but based upon comprehensively documented and detailed projection of the evolution of “Earthling” homosapiens, to become “cyborgs.” It is proposed that such long-living cyborg forms of intelligent beings would be encountered by us. The first cataclysmic encounter with them is expected to be interception of their interstellar communications. The predicted frequency of intercepted messages under one set of assumptions is at least 1500 per day. After decoding the intercepted messages, keys may be found to improve vastly the present and future quality of life for us earthlings. Advanced beings might utilize direct brain-to-brain communication and it is concluded that research into brain-to-brain communication and HFGW detection are encouraged.
