The problem of tektites

Tektites are bodies of natural glass of limited size and of typical shape and sculpturing. They occur in relatively large numbers in limited strewn-fields, each formed by a single event in the geological past. Three (perhaps four) tektite fields are known, all of different age. Perhaps only the youngest-the indoaustralian strewn-field, reaching from Thailand to Tasmania — in its original extension, the others having suffered from erosion.Many tektites from Indonesia and all from Australia show two periods of melting, which must be regarded as proof of extraterrestrial origin. These secondary forms with rims or flanges, developed by ablation in the earth's atmosphere, probably depend upon a low entry angle and are therefore only represented from certain regions.Tektites consist for about 70–80% of silica, show fluidal texture, no traces of crystallization and a remarkably low water content. From a chemical point of view they resemble certain terrestrial rocks more than true meteorites. Probably they represent molten parts from the moon's surface, which were thrown into space after the impact of large meteorites.     

Origin of planetary atmospheres

The near absence of noble gases on earth, other than those of radioactive origin, indicates that the earth was formed by the accumulation of planetesimals; this process systematically excluded all constituents that did not enter into the solid phase. The atmosphere and the ocean with many of its dissolved salts have arisen from gases emitted from the earth's interior, a process that continues today. The oxygen in the earth's atmosphere plus a greater quantity that has been removed from the atmosphere to oxidize geologic materials, has arisen mainly from a small excess of photosynthesis over decay of organic material. The atmospheres of Mars and Venus have probably arisen in a manner similar to the atmosphere on earth, by emission from the planetary interiors. However, they have not received any oxygen from photosynthesis and so are nearly oxygen free. Mars has very little water in its atmosphere, and this can be explained by its lower than freezing average surface temperature. Venus also has very little water, and this requires an ad hoc explanation; one possibility is that Venus was formed from much drier planetesimals than was the earth. Mercury and the moon are virtually without atmospheres. Although some gases may be emitted from their interiors, they are presumably rapidly lost by escape. Whatever atmosphere they possess is probably due to the neutralized solar wind that impinges upon them. The outer planets retained volatiles, including hydrogen and helium, to a much greater extent than did the terrestrial planets.     

Interaction of the moon with the earth's magnetosphere

The general characteristics and dimensions of the earth's magnetosphere, turbulent transition region, and shock wave are reviewed and examined with regard to their possible active or passive interaction with the moon. The moon may, in turn, have a wake either detectable by space experiments outside the terrestrial shock wave or capable of interacting with the earth's shock wave, wake, or magnetospheric tail. The length and detectability of such a lunar wake depend, among other factors, on the selenomagnetic field and flow characteristics of the solar wind. Direct experimental information on a lunar wake is scanty, being, in fact, limited to one supposed case recorded by the IMP-1 satellite. Some evidence has been claimed, on the other hand, for statistical relationships between geomagnetic disturbance observed at the surface and the age of the moon. These results, however, are partly conflicting with each other as regards the phase of the supposed monthly variations, and partly are lacking statistical significance or merely grazing the significance level. The proximity of the lunar period with the length of the solar rotation, as well as a yearly and half-yearly modulation of the quasi-persistent 27-day fluctuations of geomagnetic disturbance contribute to encumber the question, rendering it very difficult, with the records presently available, to free the supposed lunar effects from solar interference. It seems, therefore, recommendable to postpone a judgement on the reality of such effects.Contribución del Instituto Antártico Argentino No. 109.     

奔月转移轨道的快速设计方法研究

 结合重叠圆锥曲线方法,针对着陆型和月球卫星型两种类型奔月转移轨道,给出了一种奔月转移轨道的快速设计方法。该方法是一种无需轨道数值积分的纯代数计算方法,直接从目标轨道参数出发,具有计算速度快、精度高的特点,避免了圆锥曲线拼接法精度差的缺点,可用于这两类奔月转移轨道的初始设计。该方法可为精确轨道计算提供较好的初值,大大缩短了轨道精确计算所需的时间。同时还针对地球扁率( J2 ) 的影响,给出了一种修正方法,提高了本方法的计算精度。     

The internal constitutions of the inner planets and the moon

The internal structures of the moon, Mars, Venus, and Mercury are examined in the light of what is known about the constitution of the earth. The gravitational figure of the earth as obtained from orbits of artificial satellites is used to estimate the possible deviations from hydrostatic equilibrium on other planets. Observations of the orbital and rotational motion of the moon are consistent with the hypothesis that the interior of the moon supports density inhomogeneities of the same order as those supported by the earth. The available data on the moon are insufficient to determine whether or not the moon is differentiated. The orbits of Phobos and Deimos yield an adequate value for the moment of inertia of Mars. The moment of inertia and the mass are consistent with a metallic core containing about 10 per cent of the mass of Mars. The observations of the possible magnetic field of Mars would be of importance both to the understanding of planetary magnetic fields and elucidating the internal structure of that planet. Seismic investigations on the earth yield an equation of state for silicates to pressures of about 1 × 10⁶ bars. This equation of state is used in determining density variation within Mars.The surface heat flow for the earth is consistent with the hypothesis that the concentration of radioactive elements is the same as that in chondritic meteorites. The observed ratio of potassium to uranium in surface and near-surface rocks is not consonant with the chondritic hypothesis. The moon can be of chondritic composition only if it is differentiated with the radioactivity concentrated in the upper few hundred kilometers. A chondritic composition for Mars would require a differentiation in excess of that consistent with its mass and moment of inertia. It is concluded that a chondritic composition is not a satisfactory chemical model for the inner planets.     

月球卫星精密定轨

随着空间应用需求的日益增大,深空探测已成为现实,而月球显然是人类走向深空的首选目标。发射月球探测器通常分3个阶段,其运动状态分别对应3种不同类型的轨道:近地停泊轨道、地月转移轨道和绕月轨道。月球是1个慢自转天体且无大气,就轨道解而言这些因素导致环月卫星的运动与地球卫星有所差别。本文针对月球探测任务的特点,从月球与地球的差别入手,在仔细分析月球卫星的受力状况前提下,着重阐述月球探测器在环月段精密定轨的方法原理和具体实现过程。     

The Lunar Radar Sounder (LRS) Onboard the KAGUYA (SELENE) Spacecraft

The Lunar Radar Sounder (LRS) onboard the KAGUYA (SELENE) spacecraft has successfully performed radar sounder observations of the lunar subsurface structures and passive observations of natural radio and plasma waves from the lunar orbit. After the transfer of the spacecraft into the final lunar orbit and antenna deployment, the operation of LRS started on October 29, 2007. Through the operation until June 10, 2009, 2363 hours worth of radar sounder data and 8961 hours worth of natural radio and plasma wave data have been obtained. It was revealed through radar sounder observations that there are distinct reflectors at a depth of several hundred meters in the nearside maria, which are inferred to be buried regolith layers covered by a basalt layer with a thickness of several hundred meters. Radar sounder data were obtained not only in the nearside maria but also in other regions such as the farside highland region and polar region. LRS also performed passive observations of natural plasma waves associated with interaction processes between the solar wind plasma and the moon, and the natural waves from the Earth, the sun, and Jupiter. Natural radio waves such as auroral kilometric radiation (AKR) with interference patterns caused by the lunar surface reflections, and Jovian hectometric (HOM) emissions were detected. Intense electrostatic plasma waves around 20 kHz were almost always observed at local electron plasma frequency in the solar wind, and the electron density profile, including the lunar wake boundary, was derived along the spacecraft trajectory. Broadband noises below several kHz were frequently observed in the dayside and wake boundary of the moon and it was found that a portion of them consist of bipolar pulses. The datasets obtained by LRS will make contributions for studies on the lunar geology and physical processes of natural radio and plasma wave generation and propagation.     

Comparative study of lunar mission requirements and onboard propulsion system performance

In recent years, the lunar explorer programs, suspended for a long time, have resumed again with the rapid development of low cost and high-level technologies. As a result, several nations have made a success of lunar exploration programs with their own orbiters. Unlike a satellite orbiting the earth, the optimal design of an onboard propulsion system of a lunar orbiter is a major issue because it is not simple to make the orbiter arrive accurately at another planet far from the earth. Hence, a close attention is required to select and develop an appropriate type of the onboard propulsion system based on given mission requirements of a lunar orbiter. To do this, this study first surveys several lunar orbiters launched since 1990 and their major mission requirements. Then, it summarizes the technical trends of the onboard propulsion systems of the recent lunar orbiters and their key design and performance specifications through trade-off studies. By comparing these features, the present study investigates which lunar mission requirements are critically important, and how they can effect on the overall performance of an onboard propulsion system. Based on these investigations the major objective of the present study intends ultimately to set up a fundamental baseline in selecting and developing an appropriate type of onboard propulsion system of a lunar orbiter.     

摄动对编队飞行星座相对构型的影响分析

在近圆轨道编队飞行的假设条件下，根据动力学关系推导出了环绕卫星相对参考卫星的运动学简化模型，并以此简化模型为基础，分别研究了大气阻力摄动、日月引力摄动、太阳光压摄动和地球扁率摄动对编队飞行星座的构型影响，着重分析了地球扁率摄动周期项和长期项对构型的影响，并以此对编队轨道设计提出建议。     

Lunar photography: Techniques and results

Conclusion The lunar photography missions have included flyby, impacter, lander, and orbiter spacecrafts. These missions have provided photographs of the far side of the moon and a ten-fold increase in frontside resolution plus higher resolution of selected frontside areas. The resolutions which have been achieved vary from 1 m for the Lunar Orbiter to 1/2 m for the impacting Ranger to millimeters for Luna-IX and the Surveyors. The return from these missions have resolved much of the mystery surrounding the moon.The prime objective of the U.S. photographic missions has been the support of the Apollo-manned lunar landing program. The Ranger program, the Surveyor program, and the Lunar Orbiter program provided a logical progression in the utilization of a developing space exploration technology. These programs have provided the required information and have confirmed that the Apollo landing vehicle design is compatible with the conditions to be experienced on selected areas of the lunar surface.The future manned landing missions can be expected to provide additional lunar photography. Since the astronauts can be more selective in their photography, even more outstanding and informative results should be achieved. The addition of movies and even live television coverage will permit earth-based man to share more directly in the manned exploration of the moon.The unmanned photographic exploration of the moon has provided much of the technology required for similar missions to the planets. The U.S. Mariner-IV was the first successful mission to obtain close-up photographs of the planet Mars. It can be expected that both the U.S.A. and Russia will try for further photographic successes in the exploration of our solar system.This paper presents the results of one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology, under Contract No. NAS 7-100, sponsored by the National Aeronautics and Space Administration.     

嫦娥三号着陆器统计定位精度分析

“嫦娥三号”将在月球放置着陆器,实现月面软着陆,因此,需要对着陆器进行精确定位.本文简述了月球着陆器的统计定位方法与协方差分析理论,分析了影响统计定位精度的主要误差源.基于现有测控条件,从跟踪弧段和测量数据组合2个方面,对“嫦娥三号”着陆器的定位精度进行了分析.针对短弧条件下单站测距数据定位不稳键的问题,提出了结合月面高程约束的定位方法.协方差分析结果表明：高程数据的使用可以实现单站30 min测距优于1 km的定位精度;当观测数据累积至3d时,单站测量与VLBI（Very Long Baseline Interferometry,甚长基线干涉测量）的不同组合可以实现同等量级、优于百m的定位精度;测量系统差是制约定位精度的主要因素,完全标校测量的系统偏差则能实现10 m左右的定位精度.     

Earth-moon Trajectory Optimization Using Solar Electric Propulsion

The optimization of the Earth-moon trajectory using solar electric propulsion is presented. A feasible method is proposed to optimize the transfer trajectory starting from a low Earth circular orbit (500 km altitude) to a low lunar circular orbit (200 km altitude). Due to the use of low-thrust solar electric propulsion, the entire transfer trajectory consists of hundreds or even thousands of orbital revolutions around the Earth and the moon. The Earth-orbit ascending (from low Earth orbit to high Earth orbit) and lunar descending (from high lunar orbit to low lunar orbit) trajectories in the presence of J2 perturbations and shadowing effect are computed by an analytic orbital averaging technique. A direct/indirect method is used to optimize the control steering for the trans-lunar trajectory segment, a segment from a high Earth orbit to a high lunar orbit, with a fixed thrust-coast-thrust engine sequence. For the trans-lunar trajectory segment, the equations of motion are expressed in the inertial coordinates about the Earth and the moon using a set of nonsingular equinoctial elements inclusive of the gravitational forces of the sun, the Earth, and the moon. By way of the analytic orbital averaging technique and the direct/indirect method, the Earth-moon transfer problem is converted to a parameter optimization problem, and the entire transfer trajectory is formulated and optimized in the form of a single nonlinear optimization problem with a small number of variables and constraints. Finally, an example of an Earth-moon transfer trajectory using solar electric propulsion is demonstrated.     

Biological implications of the Viking mission to Mars

A central purpose of Viking was to search for evidence that life exists on Mars or may have existed in the past. The missions carried three biology experiments the prime purpose of which was to seek for existing microbial life. In addition the results of a number of the other experiments have biological implications: (1) The elemental analyses of the atmosphere and the regolith showed or implied that the elements generally considered essential to terrestrial biology are present. (2) But unexpectedly, no organic compounds were detected in Martian samples by an instrument that easily detected organic materials in the most barren of terrestrial soils. (3) Liquid water is believed to be an absolute requisite for life. Viking obtained direct evidence for the presence of water vapor and water ice, and it obtained strong inferential evidence for the existence of large amounts of subsurface permafrost now and in the Martain past. However it obtained no evidence for the current existence of liquid water possessing the high chemical potential required for at least terrestrial life, a result that is consistent with the known pressure-temperature relations on the planet's surface. On the other hand, the mission did obtain strong indications from both atmospheric analyses and orbital photographs that large quantities of liquid water flowed episodically on the Martian surface 0.5 to 2.5 G years ago.The three biology experiments produced clear evidence of chemical reactivity in soil samples, but it is becoming increasingly clear that the chemical reactions were nonbiological in origin. The unexpected release of oxygen by soil moistened with water vapor in the Gas Exchange experiment together with the negative findings of the organic analysis experiment lead to the conclusion that the surface contains powerful oxidants. This conclusion is consistent with models of the atmosphere. The oxidants appear also to have been responsible for the decarboxylation of the organic nutrients that were introduced in the Label Release experiment. The major results of the GEX and LR experiments have been simulated at least qualitatively on Earth. The third, Pyrolytic Release, experiment obtained evidence for organic synthesis by soil samples. Although the mechanism of the synthesis is obscure, the thermal stability of the reaction makes a biological explanation most unlikely. Furthermore, the response of soil samples in all three experiments to the addition of water is not consistent with a biological interpretation.The conditions now known to exist at and below the Martian surface are such that no known terrestrial organism could grow and function. Although the evidence does not absolutely rule out the existence of favourable oases, it renders their existence extremely unlikely. The limiting conditions for the functioning of terrestrial organisms are not the limits for conceivable life elsewhere, and accordingly one cannot exclude the possibility that indigenous life forms may currently exist somewhere on Mars or may have existed sometime in the past. Nevertheless, the available information about the present Martian environment puts severe constraints and presents formidable challenges to any putative Martian organisms. The Martian environment in the past, on the other hand, appears to have been considerably less hostile biologically, and it might possibly have permitted the origin and transient establishment of a biota.     

新一代载人月面着陆器发展趋势研究

月面着陆器是实现载人探月任务的重要组成部分,从任务规划和着陆器参数两个方面对早期美国阿波罗计划中的月面着陆器（ LM）、苏联N1-L3登月计划中的月面着陆器（ L3登月系统）以及最近美国星座计划中的月面着陆器（ Altair）的相关情况进行了分析,并从任务需求、月面环境和研究经费及基础设施方面对LM与Altair月面着陆器进行详细比较,通过比较分析总结出新一代载人月面着陆器将沿着提高乘员运送能力、扩大到达范围、延长航天员生活时间及功能模块化的方向发展,并提出研制新一代月面着陆器应着重解决着陆器推进、结构、着陆障碍检测及缓冲以及月尘防护等关键技术。     

Meteors and the abundance of interplanetary matter

Estimates of the spatial density of interplanetary dust are derived from meteor, accretion and zodiacial cloud observations. When the most recent data are considered it is found that there is no longer any serious discrepancy between the extrapolated meteor values and those from the other sources and a density distribution is obtained which extends from meteoroids capable of producing the brightest optical meteors to particles approaching the limiting size beyond which they are removed from the solar system by solar radiation pressure. Impacts on rocket and satellite vehicles lead to much higher estimates of spatial densities and it is concluded that they originate from particles in geocentric orbits belonging to a dust cloud encompassing the earth. The evidence tends to support the view that these particles are captured from the interplanetary dust cloud rather than being produced, as suggested by Whipple, through the impact of meteorites on the moon.Some suggestions are made for the direction of future rocket and satellite investigations.Contribution to the COPERS symposium on The Interplanetary medium, held in Paris on June 19, 1962.     

The interplanetary magnetic field. Solar origin and terrestrial effects

Many observations related to the large-scale structure of the interplanetary magnetic field, its solar origin and terrestrial effects are discussed. During the period observed by spacecraft the interplanetary field was dominated by a sector structure corotating with the sun in which the field is predominantly away from the sun (on the average in the Archimedes spiral direction) for several days (as observed near the earth), and then toward the sun for several days, etc. The average sector appears to be a coherent entity with internal structure such that its preceding portion is more active than its following portion. Cosmic rays corotate with the interplanetary field, and there are differential flows associated with the sector pattern. Profound effects on geomagnetic activity and the radiation belts are produced as the sector pattern rotates past the earth. The solar origin of the sector pattern is discussed. The solar source may be associated with the large-scale weak background photospheric fields observed with the solar magnetograph. It is suggested that there may be a rather continual relation between this solar structure and terrestrial responses, of which the recurring M-Region geomagnetic storms are just the most prominent example.     

月球巡视探测器自主定向算法研究

月球巡视探测器自主导航是其能在月面执行探测任务的关键,而定向又是月球巡视探测器自主导航的一个重要组成部分,其定向精度将直接影响到月球巡视探测器定位性能。将CCD(ChargeCoupleDevice)太阳敏感器应用到月球巡视探测器上,用太阳敏感器测量太阳位置矢量,结合加速度计测量的重力矢量,利用QUEST算法推算了月球巡视探测器的姿态和航向,为月球巡视探测器构建了一套适用于长时间、长距离导航的绝对定向方案,通过理论分析和实际推算描述了该定向方案的具体实现过程,最后以仿真结果验证了该方案的可行性,为下一步月球巡视探测器定位研究提供了技术参考。     

Crustal Magnetic Fields of Terrestrial Planets

Magnetic field measurements are very valuable, as they provide constraints on the interior of the telluric planets and Moon. The Earth possesses a planetary scale magnetic field, generated in the conductive and convective outer core. This global magnetic field is superimposed on the magnetic field generated by the rocks of the crust, of induced (i.e. aligned on the current main field) or remanent (i.e. aligned on the past magnetic field). The crustal magnetic field on the Earth is very small scale, reflecting the processes (internal or external) that shaped the Earth. At spacecraft altitude, it reaches an amplitude of about 20 nT. Mars, on the contrary, lacks today a magnetic field of core origin. Instead, there is only a remanent magnetic field, which is one to two orders of magnitude larger than the terrestrial one at spacecraft altitude. The heterogeneous distribution of the Martian magnetic anomalies reflects the processes that built the Martian crust, dominated by igneous and cratering processes. These latter processes seem to be the driving ones in building the lunar magnetic field. As Mars, the Moon has no core-generated magnetic field. Crustal magnetic features are very weak, reaching only 30 nT at 30-km altitude. Their distribution is heterogeneous too, but the most intense anomalies are located at the antipodes of the largest impact basins. The picture is completed with Mercury, which seems to possess an Earth-like, global magnetic field, which however is weaker than expected. Magnetic exploration of Mercury is underway, and will possibly allow the Hermean crustal field to be characterized. This paper presents recent advances in our understanding and interpretation of the crustal magnetic field of the telluric planets and Moon.     

Solid component of interplanetary matter from vehicle observations

This paper contains the data of meteoric particle investigations by means of piezoelectric detectors.The data obtained on the different Soviet vehicles at distances from about 100 km to about 100000000 km from the earth are given.Measurements have demonstrated that apart from fluxes there are individual aggregations of meteoric particles with very unequal spatial density of particles in them. Linear dimensions varied within wide limits.A concept of the mass spectrum of meteoric particles is presented.Very high concentrations of minute dust particles were observed near the earth at altitudes from 100–200 km by means of ground-based methods and rocket measurements.The increased density of interplanetary matter in the vicinity of the moon during April and May 1966 was recorded by means of satellite Luna-10. By means of Luna-12 it could not be discovered whether this aggregation is the moon halo or is the result of the moon passage through some dust particle aggregation, because the investigation on satellite Luna-12 was carried out mostly during meteor showers.     

定常幅值小推力登月飞行器轨道研究

 进行了基于平面三体模型的登月飞行器轨道控制方法的研究;研究了从近地低轨道到近月低轨道的飞行轨道;给出了在地球逃逸段、惯性漂移段和月球捕获段的运动轨迹和关键点的参数。提出使用“远地点可达”概念完成了地球逃逸段发动机推力终点的选择和使用飞行器相对月心能量完成了在月球捕获段止推发动机工作初始点的选择。