Near-Earth asteroid flyby trajectories from the Sun-Earth L2 for Chang’e-2’s extended flight

Driven by curiosity about possible flight options for the Chang＇e-2 spacecraft after it remains at the Sun-Earth L2 point, effective approaches were developed for designing preliminary fuel-optimal near-Earth asteroid flyby trajectories. The approaches include the use of modified unstable manifolds, grid search of the manifolds＇ parameters, and a two-impulse maneuver for orbital phase matching and z-axis bias change, and are demonstrated to be effective in asteroid target screening and trajectory optimization. Asteroid flybys are expected to be within a distance of 2 × 10^7 km from the Earth owing to the constrained Earth-spacecraft communication range. In this case, the spacecraft＇s orbital motion is significantly affected by the gravities of both the Sun and the Earth, and therefore, the concept of the ＂he- liocentric oscillating-Kepler orbit＂ is proposed, because the classical orbital elements of the flyby trajectories referenced in the heliocentric inertial frame oscillate significantly with respect to time. The analysis and results presented in this study show that, among the asteroids whose orbits are the most accurately predicted, ＂Toutatis＂, ＂2005 NZ6＂, or ＂2010 CL19＂ might be encountered by Chang＇e-2 in late 2012 or 2013 with total impulses less than 100 rn/s.

Climate Changes Consequences from Sun-Earth Connections and Anthropogenic Relationships

This paper is a study to understand how climate changed last fifty years. There are two theories: the first one considers the solar variability and the influence of those alterations on climate;the second one blames human activity and the consequences on temperatures and disruption on the environment created by humans. Our conclusions pointed out that dimensions involved between Earth and Sun, and Earth/Atmosphere, the second one can disturb the temperature on Earth’s surface and make seasonality variations impossible to be explained only by Sun/Earth connections.

Heteroclinic and Homoclinic Connections between the Sun-Earth Triangular Points and Quasi-Satellite Orbits for Solar Observations

Investigation of new orbit geometries exhibits a very attractive behavior for a spacecraft to monitor space weather coming from the Sun. Several orbit transfer mechanisms are analyzed as potential alternatives to monitor solar activity such as a sub-solar orbit or quasi-satellite orbit and short and long heteroclinic and homoclinic connections between the triangular points L4 and L5 and the collinear point L3 of the CRTBP （circular restricted three-body problem） in the Sun-Earth system. These trajectories could serve as channels through where material can be transported from L5 to L3 by performing small maneuvers at the departure of the Trojan orbit. The size of these maneuvers at L5 is between 299 m/s and 730 m/s depending on the transfer time of the trajectory and does not need any deterministic maneuvers at L3. Our results suggest that material may also be transported from the Trojan orbits to quasi-satellite orbits or even displaced quasi-satellite orbits.

Design of low-energy transfer from lunar orbit to asteroid in the Sun-Earth-Moon system

Asteroid exploration trajectories which start from a lunar orbit are investigated in this work.It is assumed that the probe departs from lunar orbit and returns to the vicinity of Earth,then escapes from the Earth by performing a perigee maneuver.A low-energy transfer in Sun-EarthMoon system is adopted.First,the feasible region of lowenergy transfer from lunar orbit to perigee within 5 000 km height above the Earth surface in Sun-Earth-Moon system is calculated and analyzed.Three transfer types are found,i.e.,large maneuver and fast transfers,small maneuver and fast transfers,and disordered and slow transfers.Most of feasibility trajectories belong to the first two types.Then,the lowenergy trajectory leg from lunar orbit to perigee and a heliocentric trajectory leg from perigee to asteroid are patched by a perigee maneuver.The optimal full-transfer trajectory is obtained by exploiting the differential evolution algorithm.Finally,taking 4179 Toutatis asteroid as the target,some low-energy transfer trajectories are obtained and analyzed.

地磁场与气候相关性研究五十年

地磁场与气候相关性研究五十年,人们并没有完全理解地磁场变化如何调控气候,反而更深刻地意识到这个问题远比之前想象的要复杂.本文从不同的时空尺度梳理了过去五十年间对于地磁场与气候关联性的研究.研究表明,从万年尺度的地磁倒转、千年尺度的地磁漂移、到百年尺度的考古地磁急变,甚至年代际的地磁活动变化,各种尺度的地磁场变化与气候之间都存在显著的关联.然而,相关性并不代表因果性,地磁场影响气候变化的潜在机制仍然存在争论.宇宙射线生成云机制是目前最有潜力的地磁场调控气候的过程,它在不同的时间尺度上有效地发挥作用,但其确切的物理机制和相对重要性仍然是悬而未决的问题.本文提议,应当从日地多圈层耦合的角度去理解地磁场与气候的关联性,并重点关注区域气候系统对区域磁场变化的响应.从古到今、从点到面,最终形成关联地磁场与气候变化的全球图像.如今,可精细刻画南大西洋异常区(SAA)磁场变化的澳科一号的成功发射,百年尺度的西太平洋磁异常区(WPA)的首次发现以及古地磁/考古地磁和古气候数据重构的快速发展为地磁场与气候研究提供了新的历史机遇,地磁场变化对气候的影响研究将被推向新的高潮.

天体运动的三维DDA模拟

不连续变形分析(DDA)方法广泛应用于岩土工程领域,其中三维球颗粒DDA(3D-SDDA)理论能够对球形物体模型的运动进行数值模拟。本研究将不连续变形分析方法应用于太阳系天体运行模拟,将各天体看作球状物体,仅考虑天体间的引力和其自身惯性力,通过建立系统总体平衡方程式,推导载荷矩阵方程,求解总体方程,编写Matlab计算程序,从而得到各天体的运动参数,对天体运动进行数值模拟。结果表明,利用3D-SDDA理论能够模拟日-地二体系统和日-地-月三体系统在宇宙空间中的运行状态,获取任意时刻天体的空间位置和速度信息。分别将日-地二体系统的数值计算结果与开普勒计算方法所得结果对比,日-地-月三体系统的结果与虚拟天文馆软件Stellarium高精度数据对比,结果吻合良好。同时输入月全食发生的限制条件,能够正确预测出月全食发生时刻。

Everything Is a Circle: A New Universal Orbital Model

Based on measured astronomical position data of heavenly objects in the Solar System and other planetary systems, all bodies in space seem to move in some kind of elliptical motion with respect to each other. According to Kepler’s 1st Law, “orbit of a planet with respect to the Sun is an ellipse, with the Sun at one of the two foci.” Orbit of the Moon with respect to Earth is also distinctly elliptical, but this ellipse has a varying eccentricity as the Moon comes closer to and goes farther away from the Earth in a harmonic style along a full cycle of this ellipse. In this paper, our research results are summarized, where it is first mathematically shown that the “distance between points around any two different circles in three-dimensional space” is equivalent to the “distance of points around a vector ellipse to another fixed or moving point, as in two-dimensional space”. What is done is equivalent to showing that bodies moving on two different circular orbits in space vector-wise behave as if moving on an elliptical path with respect to each other, and virtually seeing each other as positioned at an instantaneously stationary point in space on their relative ecliptic plane, whether they are moving with the same angular velocity, or different but fixed angular velocities, or even with different and changing angular velocities with respect to their own centers of revolution. This mathematical revelation has the potential to lead to far reaching discoveries in physics, enabling more insight into forces of nature, with a formulation of a new fundamental model regarding the motions of bodies in the Universe, including the Sun, Planets, and Satellites in the Solar System and elsewhere, as well as at particle and subatomic level. Based on the demonstrated mathematical analysis, as they exhibit almost fixed elliptic orbits relative to one another over time, the assertion is made that the Sun, the Earth, and the Moon must each be revolving in their individual circular orbits of revolution in space. With this expectation, individual orbital parameters of the Sun, the Earth, and the Moon are calculated based on observed Earth to Sun and Earth to Moon distance data, also using analytical methods developed as part of this research to an approximation. This calculation and analysis process have revealed additional results aligned with observation, and this also supports our assertion that the Sun, the Earth, and the Moon must actually be revolving in individual circular orbits.

地气系统辐射平衡特征的观测研究

利用温斯顿编制的美国NOAA卫星第一批 45个月辐射观测资料分析图 ,包括吸收太阳辐射、反射率及射出长波辐射 ,而地—气系统辐射平衡是用公式计算的。首次对地—气系统辐射平衡理论各分量从数值上进行逐月的和年内的纬向分布特征研究。结果表明 :在一年中太阳直射点随时间的推移在南北回归线之间移动 ,地-气系统辐射平衡、吸收太阳辐射、反射率和射出长波辐射的纬向分布 ,和理论说明的变化是完全一致的。这45个月正处于太阳黑子数相对少期 ,该期间的太阳辐射应是偏弱的。

日地系统多物理耦合机制的设计与实现

以日地系统活动规律研究为背景,通过对SCIRUN提出的PRMI进行4点改进,提出一种高效的日地系统多物理耦合交互机制PRMI++,能够在物理模型组件进行并行远程方法调用实现耦合交互的同时,自动实现网格重映射和数据并行分布重映射。实验结果证明PRMI++具有较好的性能。

基于日地月方位信息的自主导航系统的脉冲仿真和方位确定

基于日地月信息的自主导航系统利用日地和月地夹角信息来确定卫星的轨道和姿态,具有很强的应用背景。它利用在轨的集成敏感器来敏感太阳、月球和地平边缘,从而产生相应的脉冲。利用脉冲的信息就可以确定日、地、月的方位信息,并可以确定日地和月地夹角。本文研究了该类自主导航系统的基于球形地球假设的方位确定算法,导航敏感器基于地球扁率的地平脉冲、太阳脉冲和月球脉冲的产生机制,并评估了地球扁率对方位确定的影响。仿真结果表明,如果脉冲产生机制中不考虑地球扁率,由脉冲计算出的月地夹角、日地夹角的精度能达到(10-10)°。如果脉冲机制中考虑地球扁率,而方位确定中不进行修正,由脉冲计算出的月(日)地夹角与真实的月(日)地夹角的最大误差有(0.12)°。

基于日地L1点近地小行星天基观测系统的天地协同观测效能分析

小行星天基监测预警是未来行星的防御重要发展方向。开展天地协同观测可充分发挥天基、地基望远镜优势,提高系统整体的小行星天基监测预警观测效能。构建了近地小行星观测模型,分析设计了日地L1点轨道的天基观测系统方案并提出了效能评估方法,基于危地小行星数据库仿真了日地L1点轨道观测系统的协同观测效能,计算分析了相关预警效能并提出了区域和时域分工协同观测的设计构想,对未来不同天基观测系统效能评估和天地协同观测研究具有参考意义。仿真结果表明:在信噪比阈值为5的条件下,日地L1点红外、可见光系统在1年时间可对库中危地小行星编目完备率达到49.4%和38.2%,均能较好开展监测;加入地基观测站开展协同观测后,对应的系统编目完备率可分别达到58.9%和50.6%,是协同前的1.19倍和1.35倍,说明协同观测能够有效提升系统的观测效能。

日-地系拉格朗日点任务及其转移轨道设计方法

绕日-地系拉格朗日点的深空探测任务越来越多,这些任务的目标轨道一般为Halo轨道或Lissajous轨道。介绍了3种从地球停泊轨道出发到拉格朗日点的转移轨道设计方法,并进行了对比。最后以Az=-800000km的Halo轨道为例,验证了直接转移轨道设计方法的有效性。

Ice Sheet Melt and Ozone Hole Variations on Three Solar Cycles Possible Anthropogenic Interactions

This paper investigated the information about Ice sheet melt and Ozone hole variations during three solar cycles. After performing the inquiry on the data, the final results pointed out that both phenomena varying accord with Earth’s seasonality. The sea melt extension depends on the season and if the ocean waters are warmer around the polar caps. We checked the suggestion that anthropogenic perturbations could influence the variations in both phenomena.

Snowball Earth at low solar luminosity prevented by the oceanatmosphere coupling

The standard solar model proposes that the solar luminosity was 30%lower than the present level at 4.5 billion years ago(Ga).At low solar radiation,the climate model predicts that the Earth should have been completely covered by ice in the first 2 billion years,i.e.in the snowball Earth climate mode,when the atmospheric CO2 content was at the present level.However,snowball Earth condition is inconsistent with various sedimentological,paleontological,and geochemical evidence.Such controversy is collectively known as the Taint Young Sun,(FYS)paradox.Though various models have been proposed,the FYS paradox has not yet been resolved.In this study,we develop a model by considering the ocean-atmosphere coupling to show that high atmospheric CO2 level could be sustained at low seawater pH.The modeling result indicates that 0.1 bar atmospheric CO2 level that was required to prevent snowball Earth in early Archean could be sustained at seawater pH of 6.8-7.2.Although the absence of siderite in Archean paleosols has been used to argue against high atmospheric CO2 level,we suggest that siderite precipitation in paleosols was not controlled by the atmospheric CO2 level alone.Instead,siderite could precipitate in anoxic conditions with various amount of CO2 in the atmosphere,suggesting siderite cannot be used to reconstruct the atmospheric CO2 level.Therefore,the new model suggests that the snowball Earth condition could be prevented by the coupling of atmosphere and ocean systems,and thus the emergence of the ocean in the very beginning of Earth evolution might be the key to the subsequence evolution of habitability.

Rethinking the Earth in the Solar System

The recent discovery that the Earth is retarding each year by a fraction of a second its revolution around the Sun led to investigations and speculations about the cause of such a defect in what was thought to be a perfect clock. The emission of thermal radiation by the Sun cannot justify this discrepancy even if a fraction of unknown dark matter is added to increase the Sun mass loss. The increase of distance of Earth/Moon center of mass from the Sun is estimated of the order of one centimeter per year. However experimental measurements suggest values of the order from 5 to 15 centimeters, hard to be measured for the distances involved. To solve this problem, sophisticated orbital analysis has been proposed, changes in the gravitational constant G have been suggested and more precise mass/distance measurements in the solar system, asteroids included, have been requested. The present paper shows how the use of an elementary model for the Earth/Moon orbit together with a new theory for the gravitational constant G, coherent with Newton law, can solve this problem. The comprehension of gravity, the ultimate unexplained force of the universe, is the key to solve this and the many remaining question marks in the books of physics.

A Consistent Model of Terrestrial Planet Magnetospheres and Rotations in Our Solar System

The Sun comprises 99.9% of the solar system mass so it is expected that Sun terrestrial planet interactions can influence the motion as well as the rotation of the terrestrial planets. Gravity affects the planet orbital motions while the changing magnetic fields of the Sun can influence the planet rotations. Planets that manifest a magnetic field dominate any weaker magnetic fields from the Sun, but the rotation of terrestrial planets without a magnetic field interacts with the changing Sun’s field dependent on the electrical conductivity of the core region. It is determined that the average planet density becomes a useful quantity to describe the magnetic state of a terrestrial planet. An average density of 5350 ± 50 kg/m3 is hypothesized to separate planets that develop magnetospheres from those that do not. Planets with higher average densities, Mercury and Earth, developed magnetospheres. While those with lower average densities, Venus and Mars never developed magnetospheres. Terrestrial planets with magnetospheres are the ones to also exhibit plate tectonics. The small size of Mercury led to Mercury only exhibiting a frozen in magnetization of potentially magnetic regions. The lack of magnetospheres as well as lack of plate tectonics prevented the continual transfer of core heat to the surface that limited the surface vulcanism to an initial phase. For Venus, it meant that the surface regions would only sporadically convulse. In this picture, the apparent anomalous axial rotation of Venus is a natural consequence of the rotation of the Sun. For Mars with relatively low surface temperatures, it meant that there was little heat exchange through the crust that would allow the lower crust to retain large amounts of water. For Mars to have initially had flowing liquid water required that the atmosphere at that time contained high concentrations of infrared absorbing gases at least as compared to the present level of infrared absorbing gases on the Earth. The terrestrial planets have iron based cores because iron has the highest binding energy per nucleon that can be made in the steady state lives of massive stars no matter how massive. This suggests that many of the conclusions reached here may also be applicable to exoplanets.

Correlations between the Rotations and Magnetospheres of the Terrestrial Planets and the Sun’s Formation in Our Solar System

Correlations between the rotations of the terrestrial planets in our solar system and the magnetic field of the Sun have been previously noted. These correlations account for the opposite rotation of Venus as a result of the magnetic field of the Sun being dragged across the conducting core of Venus. Currently, the Sun’s magnetic field is not sufficiently strong to account for the proposed correlations. But recently meteorite paleomagnetism measurements have indicated that during the Sun’s formation the magnetic field of the Sun was of sufficient strength to have resulted in the observed correlations. Also, dating back to the Sun’s formation are measurements showing that the Sun’s core rotates four times faster than the Sun’s surface. Both the counter rotation of Venus and the initial period of strong Sun magnetic fields are believed to be relics of the time period when the Sun’s core to surface differential rotation was established. As a part of these correlations, it was hypothesized that for a terrestrial planet to exhibit a magnetosphere, the average density must be ≥5350 ± 50 kg/m3. On this basis, only the Earth and Mercury would have formed initial magnetospheres, while Venus, Mars, and the “Moon” would not have developed magnetospheres. For such correlations to still be present today requires our Sun to have been formed as a sole star and with what might be termed a friendly Jupiter. Otherwise, the observed correlations would have been disrupted over time.

The Truth behind the Solar System in the Universe

This research focuses on multiple facts regarding the earth gravity and the space mechanism, mainly on the solar systems including the Sun and the planets belonging to it. Our solar system consists of our star, the Sun, and everything bound to it by gravity based on Albert Einstein and Isaac Newton theories. The planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto, dozens of moons, millions of asteroids, Comets and meteoroids [1]. Also, it will discuss about The Geocentric model and how scientifically proofed that the Earth is not orbiting the sun as it has a fixed position in the universe with the rotation around its axis and the sun is orbiting the Earth in one solar year. The output of the Geocentric model led to that the gravity is a feature generated by the planet itself to be measured reference to the weight granted to the matter.

小天体多目标多模式探测任务设计

多目标多模式小天体探测具有降低任务成本、增加科学回报的优点,本文针对多目标多模式小天体探测任务中摄动敏感、约束复杂以及推力幅值变化等任务规划的设计难题,研究了地球准卫星采样返回以及主带彗星交会探测任务的转移轨道设计问题.首先,介绍了探测目标的科学价值并根据任务约束给出探测任务构想.其次,基于椭圆型限制性三体问题,考虑星历、发射能量和采样返回再入速度等约束,设计并优化了地球准小行星目标的多脉冲采样返回轨道,实现地球发射与返回段和星际转移段全过程的精确飞行设计.最后,根据任务约束,推导了推力幅值可变的最优小推力转移轨道的一阶必要条件并给出考虑借力约束的初值选取方法.以采样后火星借力探测主带彗星为例,求解并分析了最大推力幅值衰减的小推力交会轨道.本文的研究方法可为我国未来的深空探测任务提供参考.

Challenges of modeling solar disturbances' arrival times at the Earth

In recent years remarkable advances have been made in the development of phys-ics based models of various parts of the solar-terrestrial system (see JASTP special issues, October, November 2004; February 2007). In this paper, we focus our dis-cussions in a specific region of the Sun to the Earth’s environment (i.e. 1 AU). It is well-known that geomagnetic storms are caused by solar eruptions. The conse-quences of these storms include particle acceleration, solar wind impact on the Earth’s magnetosphere and ionosphere, UV-EUV radiation effects on the lower at-mosphere, etc. One of the main challenges is to predict the arrival time at 1 AU of the solar disturbance. The prospects look good for an accurate, real-time forecast scheme built on the acquisition of solar, heliosphere and the near-Earth data and large-scale models. However, the accuracy of these models still needs improve-ment. We will discuss the present status of the models and challenges to improve the simulation models.