Prospective results of CHANG'E-2 X-ray spectrometer

The Chinese second lunar satellite CE-2, which carries an X-ray spectrometer (XRS), will be launched at the end of 2010.In order to estimate the scientific results of XRS, we simulate the anticipated lunar X-ray spectra observed by XRS by using the expected mean solar X-ray flux in 2011.We also obtain the integration time and the spatial resolution required to achieve a certain significance level for the major lunar rock-forming elements in different solar activity conditions.It is expected that a spatial resolution of finer than 100 kilometers can be achieved for elements Mg, Al, Si, Ca, Ti, and Fe.     

基本参数法在地面验证实验中的的应用

As the nearest celestial body to the earth, the moon has become a hot spot again in astronomy field recently. The element analysis is a much important subject in many lunar projects. Remote X-ray spectrometry plays an important role in the geochemical exploration of the solar bodies. Because of the quasi-vacuum atmosphere on the moon, which has no absorption of X-ray, the X-ray fluorescence analysis is an effective way to determine the elemental abundance of lunar surface. The CE-1 X-ray fluorescence spectrometer （CE-1/XFS） aims to map the major elemental compositions on the lunar surface. This paper describes a method for quantitative analysis of elemental compositions. A series of ground base experiments are done to examine the capability of XFS. The obtained results, which show a reasonable agreement with the certified values at a 30% uncertainty level for major elements, are presented.     

Quantitative analysis results of CE-1 X-ray fluorescence spectrometer ground base experiment

As the nearest celestial body to the earth, the moon has become a hot spot again in astronomy field recently. The element analysis is a much important subject in many lunar projects. Remote X-ray spectrometry plays an important role in the geochemical exploration of the solar bodies. Because of th equasi-vacuum atmosphere on the moon, which has no absorption of X-ray, the X-ray fluorescence analysis is an effective way to determine the elemental abundance of lunar surface. The CE-1 X-ray fluorescence spectrometer (CE-1/XFS) aims to map the major elemental compositions on the lunar surface. This paper describes a method for quantitative analysis of elemental compositions. A series of ground base experiments are done to examine the capability of XFS. The obtained results, which show a reasonable agreement with the certified values at a 30% uncertainty level for major elements, are presented.     

Mitigation of lunar dust on solar panels and optical elements utilizing electrostatic traveling-wave

A system for removing lunar dust from the surface of solar panels and optical elements is of great importance for lunar exploration. We have developed a method of removing lunar dust using electrostatic traveling-waves generated by four-phase rectangular voltage applied to a transparent conveyer consisting of parallel ITO (indium tin oxide) electrodes printed on a glass substrate. On the basis of basic investigations, we have demonstrated the removal of actual lunar dust. A numerical investigation predicts that the performance will improve in the low-gravity environment on the Moon.     

Charge states of inert gas ions in lunar ilmenites

Fractionation of particles of solar corpuscular radiation significantly changes from flare to flare; therefore the average regularities derived from the contents of inert gases in lunar samples of different cosmicray exposure age are of particular importance. Simulation of the charge states of inert gas ions (Ne, Ar, Kr, and Xe) in lunar ilmenites suggests possibility of higher solar flare activity and higher hardness of the solar proton spectrum ～1 billion years ago.     

Solar wind and cosmogenic rare gases in Luna 16 and 20 soils and their correlation with cosmic ray produced fossil tracks in lunar samples

The elemental and isotopic composition of Ne, Ar, Kr and Xe were measured in the bulk soil samples obtained from Luna 16 and 20 missions. The average cosmic ray exposure ages for the Luna 16 soils is higher than that of Luna 20 soils. The trapped solar wind composition is deduced by correcting for the cosmogenic component and is found to be in good agreement with the values published by others. The correlation between the solar wind gases and cosmic ray tracks in lunar samples is quantitatively studied and some systematic features regarding lunar regolith dynamics are tentatively established.     

Distribution of charged lunar dust in the south polar region of the moon

Lunar dust is one of the most threatening problems confronting the return of human beings to the moon. In this work we studied the spatial distribution behavior of charged lunar dust in the solar wind plasma environment in the south polar region of the moon and considered the influence of a mini-crater using Spacecraft Plasma Interactions Software. The distribution of dust and plasma at low solar altitude angles of 20° and 0° was studied, and the spatial density of lunar dust was ~10^10.4 m^-3 and ~10^11.5 m^-3, respectively. This is because a higher surface potential will result in transportation of small dust particles and photoelectrons can also neutralize positively charged lunar dust. The dust density in the plasma void region created by a mini-crater with a 5 m high wall was studied. We obtained a quasi-neutral electric environment in the plasma void region of the mini-crater, and the dust density was about a magnitude lower than that in other regions. The dust risk to a spacesuit is much lower on the nightside than on the dayside, but there is severe charged lunar dust transport in the region between light and shade, which is dominated by the difference in surface and plasma potential caused by photoelectrons.     

X‐ray‐Raman‐scattering‐based EXAFS beyond the dipole limit

X‐ray Raman scattering (XRS) provides a bulk‐sensitive method of measuring the extended X‐ray absorption fine structure (EXAFS) of soft X‐ray absorption edges. Accurate measurements and data analysis procedures for the determination of XRS‐EXAFS of polycrystalline diamond are described. The contributions of various angular‐momentum components beyond the dipole limit to the atomic background and the EXAFS oscillations are incorporated using self‐consistent real‐space multiple‐scattering calculations. The properly extracted XRS‐EXAFS oscillations are in good agreement with calculations and earlier soft X‐ray EXAFS results. It is shown, however, that under certain conditions multiple‐scattering contributions to XRS‐EXAFS deviate from those in standard EXAFS, leading to noticeable changes in the real‐space signal at higher momentum transfers owing to non‐dipole contributions. These results pave the way for the accurate application of XRS‐EXAFS to previously inaccessible light‐element systems.     

Terrestrial Seismic Activity and Neutrons from the Surface of the Earth Associated with Lunar and Solar Tides

drastic increase in the flux of thermal neutrons of secondary cosmic radiation coming from the Earth was observed in the Pamir Mountains during the solar eclipse of July 22, 1990. In the following years, such phenomena were observed on each new moon and each full moon, when lunar and solar tides combine to produce an exceptionally high resultant tide. Tidal forces may serve as a trigger for the release of the deepearth seismic energy in a certain region. This directed our attention to the search for a temporal correlation between earthquakes and new and full moons, which may help identify a new type of seismic activity precursor. Such a correlation was found in the circum-Pacific belt and the adjacent regions at latitudes above 40° N and 10° S. The results of daytime measurements of the thermal neutron flux from the surface of the Earth in the Western Pamirs (Moskvin Glade, 4200 m above sea level) on August 1–14, 1994, are reported in the present study. Since these days were quiet in terms of weather and heliophysical and geophysical activity, the intensity of neutrons of secondary cosmic radiation was expected to remain almost constant. However, twofold (or even larger) intraday variations of the neutron count rate were observed on August 1–14, 1994. These quiet measurement conditions rule out the possibility that these bursts were associated with certain known extraterrestrial factors. It has been demonstrated that the observed neutron-intensity peaks were produced by lunar and solar tides. These results confirm that tidal forces play a prominent part in the generation of neutron fluxes from the surface of the Earth. The Astronomical Yearbook for 1994 published by the Russian Academy of Sciences was used in the present study.     

月球表面遥感图像阴影消除及其信息恢复研究

由于月球表面的地形起伏引起月面遥感图像像素与太阳相对位置和几何取向不一致,导致月面遥感数字图像上阴影像素的产生。为了解决这一问题,利用与遥感图像匹配的DEM和光照方位参数进行遥感图像的阴影判断,基于DEM数据,利用邻坡反射辐射,进行自然地形条件下的月表遥感图像阴影像素的阴影消除,恢复成太阳光谱照度相等（入射角,反射角和距离相同）时的像素遥感值。仿真实验结果表明：该方法较好地消除了月表影像的阴影,充分恢复了月表影像的反射/光谱特征。     

A new application of X‐ray scattering using principal component analysis – classification and identification of liquid precursor chemicals

X‐ray scattering (XRS) combined with principal component analysis has been utilized for classifying and identifying liquid precursor chemicals for the first time. The XRS spectra of some liquid precursor chemicals and normal materials were obtained by using an XRS system, and the profiles of scattering media distinctly reveal that the XRS spectra are unique corresponding to the specific liquid material. Furthermore, the obtained spectra were processed through principal component analysis by using the selected energy region in the spectra. The score plots of each substance were clustered together and almost coincident for the same liquid, implying good repeatability and reliability. As far as the different liquid materials are concerned, they could be classified into distinct groups according to their positions in the score plot. The score plots showed a clear classification and recognition of liquid precursor chemicals. This study demonstrates a possibility for analyzing different liquid materials, and it presents a new application for X‐ray spectroscopy. Copyright © 2012 John Wiley & Sons, Ltd.     

Atmospheric aerosol limb scanning based on the lunar eclipses photometry

The work is devoted to the analysis of the surface photometric observations of two total lunar eclipses in 2004. The lunar surface relative brightness distribution inside the umbra was used to retrieve the vertical distribution of aerosol extinction of the solar radiation expanding by a tangent path and its dependence on the location at the limb of the Earth. The upper altitude of troposphere aerosol layer was estimated for different latitude zones. The correlation between additional aerosol extinction in the upper troposphere and cyclones was investigated.     

The Usage of Fundamental Parameter Method in Ground-base Experiment for Quantitative Analysis

As the nearest celestial body to the earth, the moon has become a hot spot in astronomy researches again recently [1-3], while the resource exploration is of much importance for lunar project. For the quasi-vacuum atmosphere in the moon, X-ray quantitative analysis is a effective way to determine concentration of the element on lunar surface, especially for determination of Mg, Al and Si[1,4]. As one of the ChangE-1’s payloads, the X-ray spectrometer is aiming to map the global elements distribution on the lunar surface. The X-ray Spectro-graph is examined on ground for its usage for quantitative analysis in deep space mission, and the results are in accord with the certified values.     

Accelerator irradiations of minerals: Implications for track formation mechanisms and for studies of lunar and meteoritic materials

Abstract

Natural crystals of feldspars, pyroxenes, quartz and apatite have been irradiated in the Berkeley HILAC with neon and argon ions of up to 10.2 MeV/amu with maximum doses of 1.6 × 10¹³ argon ions/cm² and 4.0 × 10¹³ neon ions/cm² respectively. The samples were thinned to thicknesses near 30 microns, stacked to form the target and then bathed completely in the ion beams. X-ray and optical observations revealed: (a) a crystal distortion and curvature with the argon irradiation similar to that produced in mica; (b) a lesser effect from neon bombardment; (c) a fracturing of the crystal samples which depended on the total dose and energy of the incident ion; (d) polygonized structures produced when either neon or argon ions (with sufficiently high concentration) were trapped within the crystals. The interpretation of the measurements, their correlation with the mechanism of track formation and implications concerning the alteration of the lunar surface due to solar particles and the exposure of lunar and meteoritic material in the ancient solar flare cosmic rays are discussed.     

Lunar soil as shielding against space radiation

We have measured the radiation transport and dose reduction properties of lunar soil with respect to selected heavy ion beams with charges and energies comparable to some components of the galactic cosmic radiation (GCR), using soil samples returned by the Apollo missions and several types of synthetic soil glasses and lunar soil simulants. The suitability for shielding studies of synthetic soil and soil simulants as surrogates for lunar soil was established, and the energy deposition as a function of depth for a particular heavy ion beam passing through a new type of lunar highland simulant was measured. A fragmentation and energy loss model was used to extend the results over a range of heavy ion charges and energies, including protons at solar particle event (SPE) energies. The measurements and model calculations indicate that a modest amount of lunar soil affords substantial protection against primary GCR nuclei and SPE, with only modest residual dose from surviving charged fragments of the heavy beams.     

The comparative analytical performance of the Beagle 2 X‐ray Spectrometer for in situ geochemical analysis on Mars

The Beagle 2 X‐ray Spectrometer (B2 XRS) instrument was part of the Beagle 2 Mars lander payload and intended to perform in situ geochemical analyses of geological materials on Mars. The analytical performance of a spare version of the B2 XRS was compared with (1) a portable X‐ray fluorescence (PXRF) spectrometer designed to perform terrestrial fieldwork and (2) a laboratory‐based wavelength‐dispersive (WD‐XRF) system used to produce high quality geochemical data. The criteria used to assess the performance were based on fitting precision, accuracy and detection limit, determined from the analysis of international geochemical reference materials. The fitting precision of the B2 XRS and PXRF was found to be in agreement with the Horwitz function (a benchmark relating the analysed concentration of an analyte to its uncertainty) over 4 orders of magnitude of concentration range from 10^?1 to 10^?5 g/g. The PXRF generally had a better fitting precision than the B2 XRS because of its better resolution. In order of improving accuracy, the spectrometers generally are ranked B2 XRS, PXRF and WD‐XRF for various major and trace elements. A limiting factor in the accuracy of the B2 XRS was the application of the algorithm used for its quantitative analysis. The detection limits for the spectrometers ranked in the same order as the accuracy as a result of improving signal‐to‐noise ratio (SNR) of elemental peaks, which is a direct consequence of improving resolution between these spectrometers. Overall, the B2 XRS was found to have a favourable analytical performance compared to the benchmark spectrometers, despite having met considerable design constraints and qualification tests as a planetary instrument. Copyright © 2009 John Wiley & Sons, Ltd.     

Solar and lunar tides in the geomagnetic field

Amplitudes of spectral geomagnetic field components and signal/noise ratios are estimated at frequencies of lunar and solar tides based on the data registered at the experimental site of Vladimir State University (VlSU) and Japanese geomagnetic stations Kakioka (1913–2006) and Memambetsu (1950–1999). The influence of thermal solar tides S1, S2, S3, and S4 and lunar gravitational tides O1, M2, and N2 on the geomagnetic field of the surface layer of the atmosphere is reliably distinguished.     

Impacts of fast meteoroids and a plasma–dust cloud over the lunar surface

The possibility of the formation of a plasma–dust cloud in the exosphere of the Moon owing to impacts of meteoroids on the lunar surface is discussed. Attention is focused on dust particles at large altitudes of ~10–100 km at which measurements were performed within the NASA LADEE mission. It has been shown that a melted material ejected from the lunar surface owing to the impacts of meteoroids plays an important role in the formation of the plasma–dust cloud. Drops of the melted material acquire velocities in the range between the first and second cosmic velocities for the Moon and can undergo finite motion around it. Rising over the lunar surface, liquid drops are solidified and acquire electric charges, in particular, owing to their interaction with electrons and ions of the solar wind, as well as with solar radiation. It has been shown that the number density of dust particles in the plasma–dust cloud present in the exosphere of the Moon is ?10^?8 cm^?3, which is in agreement with the LADEE measurements.     

Long term variations of solar radius

Total and annular eclipses allow us to measure the angular solar diameter at unit distance up to an accuracy of some hundredths of arcsecond. Data of lunar limb features from Japanese mission Kaguya will be useful to detect also the solar oblateness signal, relevant from a General Relativistic point of view. Useful eclipse data are available for 1567, 1715, 1869, 1925 and from 1966 to 2009 with uneven sampling: only these data can allow a study of solar diameter evolution with significant resolution on secular basis.     

X射线光谱在生命起源和全球气候变化等若干重大科学问题中的研究进展

生命起源、全球气候变化等是关系到人类未来命运的重大科学问题,X射线光谱(XRS)可原位测定物质组成与元素形态,在解决重大科学问题、揭示自然规律中发挥了重要作用:(1)在生命起源探索中,通过RNA结构和海洋热液自养体系元素形态分析,揭示了RNA形成机制和生物地球化学规律;(2)在地球早期生命研究中,通过沉积纹层、细胞组构...