基于离子推进技术的轨道转移设计

将太阳能离子推力器应用于卫星的推进系统,完成从地球同步转移轨道(GTO)到地球同步轨道(GEO)转移任务;建立任务模型,设计基于纬度幅角的反馈控制策略,对发动机开关时间进行优化.采用图形处理器（GPU, graphic processing unit）加速的遗传算法(GA,genetic algorithm)对卫星转移轨道任务进行优化设计.仿真结果表明：通过对该闭环控制器的定常参数进行优化,可将轨道导引至目标轨道附近;采用太阳能离子推力器可减少燃料消耗.基于GPU加速的遗传算法,可缩短算法运算时间.     

基于网格细化技术的地球-火星转移轨道优化

文章从细化效率、易用性和适应性等角度对基于数据压缩原理的网格细化算法进行改进,与基于局部配点法开发的通用轨迹优化方法（考虑非线性规划的规范化处理、稀疏特性和数值微分算法）相结合,构建出一种非光滑轨迹优化方法。对地球—火星转移轨道进行了优化,结果表明：所述方法能够高精度、快速求解地球—火星转移轨道优化问题,能够在轨道变化剧烈区域加密网格,在轨道变化平坦区域采用较稀的网格,具有较好的适应性和在线优化的潜力;采用控制变量作为网格细化函数即可捕捉到状态变量的剧烈变化;对于地球—火星转移轨道优化问题,推力方向角定义在[0°,360°)比定义在[-180°,180°)更利于数值优化。     

基于人工免疫算法的地球-火星小推力转移轨道优化

利用人工免疫算法研究了地球-火星小推力转移轨道优化问题。首先针对地球-火星转移轨道的特点建立系统模型并进行归一化处理;然后通过参数化和罚函数将小推力轨道优化问题转化为非线性规划问题;最后提出一种引导型人工免疫算法(Guiding Artificial Immune Algorithm,GAIA)并对该优化问题进行寻优。仿真算例表明,该算法收敛速度快,寻优精度高,且避免了初值敏感、病态梯度和局部收敛等问题;同时验证了GAIA用于小推力轨道优化的有效性。     

日地系L2点与日火系L1点转移轨道设计

将太阳-地球-火星-飞行器组成的四体问题分解成由太阳-地球-飞行器和太阳-火星-飞行器两个共面圆形限制性三体问题,设计日地系L2点与日火系L1点Lyapunov轨道之间的转移轨道,该转移轨道可以作为探测火星时的低能中间转移轨道.采用Richardson三阶近似解作为初始值,运用微分修正方法分别得到两个不同三体系统下拉格朗日点的精确Lyapunov轨道.基于Lyapunov轨道不变流形以及微分修正方法,设计了日地系L2点与日火系L1点间的转移轨道.将所得结果与基于Halo轨道不变流形设计的转移轨道进行了对比.结论表明:利用Lyapunov轨道不变形设计探火中间转移轨道相较于利用Halo轨道不变流形设计探火中间转移轨道在能量消耗以及飞行时间上都存在优势.     

基于粒子群算法的电帆轨迹优化设计

电帆是一种利用太阳风动量的新颖的无工质空间推进系统,文章研究了以电帆为对象的行星际转移轨迹优化问题。以地球轨道转移到火星、金星轨道为任务对象,采用连续推力模型,研究极坐标系下最小时间转移轨迹优化设计问题。提出了两种基于粒子群算法(PSO)的直接优化方法,避免对协态变量初值敏感的两点边值问题（TPBVP）求解。方法一是通过打靶法直接离散化控制量输入,将最优控制问题转化为非线性规划参数优化问题,采用PSO算法寻优,获得近似最优的转移轨迹。方法二是针对任何连续控制律曲线都能以一定精度的多项式函数进行曲线拟合的特性,设计逼近最优转移轨迹控制律的多项式函数,通过PSO算法优化多项式函数参数获得逼近最优解的转移轨迹。仿真结果表明采用上述两种方法进行转移轨迹优化设计,具有随机猜测初值、全局收敛、鲁棒性强的特点。     

基于遗传算法的最优Lambert双脉冲转移

研究了初始位置和转移时间不固定的Lambert双脉冲轨道转移的数值解,用三 维图和截面图直观显示了初始位置、转移时间和速度增量的关系,并说明了其在实际工程任 务中的应用价值.基于数值解,提出了Lambert双脉冲轨道转移的优化问题.目标是找到最 优初始位置和转移时间,使燃料和时间的加权和最小.给出了遗传算法求解该优化问题的设 计步骤.该算法应用于2个算例:①平面圆轨道的燃料最优转移,并将遗传算法和Hohmann 转移的结果进行了比较;②椭圆轨道、初始位置有约束的燃料和时间最优转移.结果说明 了遗传算法寻找最优转移解是准确有效的.      

GEO/IGSO混合区域导航星座的设计与优化算法

区域导航星座能够以较低成本和较短时间获得目标区域导航能力，且地球同步轨道是构建非极区区域导航星座的重要轨道类型。提出一种基于GEO（地球静止轨道）和IGSO（倾斜地球同步轨道）的区域导航星座设计方法。基于星下点轨迹特性构造对称星座设计参数和优化参数集，并考虑地球扁率长期摄动影响，计算星座轨道参数。以导航服务区的统计GDOP（几何精度因子）为目标函数，利用差分进化算法构建星座优化模型。以印度IRNSS的7星星座为例，仿真检验了设计和优化算法的正确性，讨论了IRNSS星座优化构型和轨道类型选取。本方法采用的对称星座设计参数少，能够提升GEO/IGSO混合区域导航星座的全局优化效率，为后续非对称星座快速提供最佳星数和构型设计。     

载人火星探测飞行方案

对世界各国载人火星探测的研究情况进行了简要综述,研究了国内外有关载人火星探测飞行方案,提出了载人火星探测方案确定的原则和方案基本思想.给出了一种载人火星探测飞行方案的总体设计,包括飞行轨道方案和载人火星飞船方案等.尤其对轨道设计的重要的两个参数——速度增量和飞行时间进行了详细计算.最后给出了飞行轨道选择、火星飞船从地球到火星和从火星返回地球等的轨道方案和火星飞船各组成部分方案的详细设计结果.     

行星悬浮轨道保持控制研究

针对太阳帆航天器行星悬浮轨道保持控制问题进行了研究.首先，建立了柱坐标系下太阳帆动力学模型；然后，对模型进行线性化处理，推导出太阳帆状态方程；接着，设计线性二次型调节器(LQR)及基于遗传算法(GA)改进的控制器，对出现扰动的轨道进行控制；最后，通过仿真结果对比，表明上述控制器均可实现轨道保持控制，且基于GA改进的LQR性能明显优于传统LQR.     

地球同步轨道卫星混合推进转移轨道特性分析

以地球同步轨道卫星转移轨道设计为背景，针对全化学推进燃料消耗大和全电推进转移时间长的问题，开展了化学 电混合推进转移轨道优化设计与特性分析。首先，讨论了轨道倾角和近地点幅角变化对混合推进转移轨道的影响。研究表明，在混合推进优化设计中需要将轨道倾角作为优化变量之一。然后，以近地点半径、远地点半径、轨道倾角为优化变量生成搜索网格，得到过渡轨道集。针对每条过渡轨道，构建化学推进转移段和电推进转移段。其中化学推进段采用单圈兰伯特转移解算，电推进段采用混合法优化。最后，以燃料消耗和转移时间为指标，在搜索域内开展解算分析，研究了混合推进轨道在整个搜索域内的变化趋势。该方法可以提供具有不同燃料消耗和转移时间的混合推进转移解集，拓宽了解空间，可供轨道设计人员根据任务约束灵活选用。     

Extrasolar space exploration by a solar sail accelerated via thermal desorption of coating

For extrasolar space exploration it might be very convenient to take advantage of space environmental effects such as solar radiation heating to accelerate a solar sail coated by materials that undergo thermal desorption at a particular temperature. Thermal desorption can provide additional thrust as heating liberates atoms, embedded on the surface of the solar sail. We are considering orbital dynamics of a solar sail coated with materials that undergo thermal desorption at a specific temperature, as a result of heating by solar radiation at a particular heliocentric distance, and focus on two scenarios that only differ in the way the sail approaches the Sun. For each scenario once the perihelion is reached, the sail coat undergoes thermal desorption. When the desorption process ends, the sail then escapes the Solar System having the conventional acceleration due to solar radiation pressure. We study the dependence of a cruise speed of a solar sail on perihelion of the orbit where the solar sail is deployed. The following scenarios are considered and analyzed: (1) Hohmann transfer plus thermal desorption. In this scenario the sail would be carried as a payload to the perihelion with a conventional propulsion system by a Hohmann transfer from Earth’s orbit to an orbit very close to the Sun and then be deployed. Our calculations show that the cruise speed of the solar sail varies from 173?km/s to 325?km/s that corresponds to perihelion 0.3?AU and 0.1 AU, respectively. (2) Elliptical transfer plus Slingshot plus thermal desorption. In this scenario the transfer occurs from Earth’s orbit to Jupiter’s orbit; then a Jupiter’s fly-by leads to the orbit close to the Sun, where the sail is deployed and thermal desorption comes active. In this case the cruise speed of the solar sail varies from 187?km/s to 331?km/s depending on the perihelion of the orbit. Our study analyses and compares the different scenarios in which thermal desorption comes beside traditional propulsion systems for extrasolar space exploration.     

Controlled solar sail transfers into the near-sun orbits

We present results of numerical simulations of trajectories of a space probe with a flat solar sail which moves from a circular Earth orbit to near-Sun regions. We consider the upper limit of the sail temperature as the basic restriction. We also examine the planar (ecliptic) solar sail transfer with gravity-assist flybys around planets.     

太阳帆飞行器轨道动力学分析

通过分析对轨道要素影响最大的加速度分量,使太阳帆总是位于光压力沿这个加速度方向的分量最大的方位。通过分析轨道要素调整时的相互影响关系,提出了同时修正多种轨道偏差的控制方案。对处于地球静止轨道上太阳帆飞行器的轨道调整进行了数值仿真。结果证明利用太阳光压力进行轨道调整是可行的,而且有利的太阳方位是进行快速有效的轨道调整的必要条件。     

Solar sail near the Sun: Point-like and extended models of radiation source

Some modifications of solar sail radiation pressure forces on a plate and on a sphere for use in the numerical simulation of ‘local-optimal’ (or ‘instantaneously optimal’) trajectories of a spacecraft with a solar sail are suggested. The force model development is chronologically reviewed, including its connection with solar sail surface reflective and thermal properties. The sail surface is considered as partly absorbing, partly reflective (specular and diffuse), partly transparent. Thermal balance is specified because the spacecraft moves from circular Earth orbit to near-Sun regions and thermal limitations on the sail film are taken into account. A spherical sail-balloon can be used in near-Sun regions for scientific research beginning with the solar-synchronous orbit and moving outward from the Sun. The Sun is considered not only as a point-like source of radiation but also as an extended source of radiation which is assumed to be consequently as a point-like source of radiation, a uniformly bright flat solar disc and uniformly bright solar sphere.     

太阳帆航天器编队维持和重构的方法研究

针对高面质比航天器可以利用太阳光压进行轨道控制的特点,本文提出一种太阳帆航天器编队构型维持和重构的方法.该方法通过控制主从航天器太阳帆姿态角和反射系数,调整主从航天器之间的光压差,产生抵消编队成员间相对运动受到摄动差或进行轨道机动时所需的连续小推力,从而实现编队构型的维持和重构.仿真结果表明,在主航天器太阳帆的姿态角和反射系数相对固定的条件下,对于太阳同步轨道上的高面质比太阳帆航天器编队,使用滑模控制方法,能够调整编队中从航天器太阳帆的姿态角和反射系数产生推力抵消摄动力影响,达到长期维持太阳帆航天器编队构型的目的;通过开环控制方法,能够调整编队中从航天器太阳帆的姿态角和反射系数产生连续小推力,在较长时间周期内实现编队重构.     

Influence of optical parameters on a solar sail motion

Detailed dynamic modeling of a solar sail requires recording of solar radiation pressure influence. A photon-solar sail is determined by the thrust value and the direction. We define the solar sail’s reflectivity depending on the film materials, the sail design and temperature, the thickness of multiple layers, and degradation factor, with a reasonable degree of accuracy. Thus, this work is devoted to the identification of optical characteristics of thin multilayer films in space flight conditions, i.e. to finding its reflectance, absorbance, and transmittance. In particular, the paper asks whether the solar sail simulates by a mathematical model of the optical characteristics of a multilayer epitaxial thin film. The temperature change effect and optical properties of solar sail degradation are considered as well. Solar sail flight from Earth to Mercury is designed as a simulation of the flight change in optical parameters.     

CubeSail: A low cost CubeSat based solar sail demonstration mission

CubeSail is a nano-solar sail mission based on the 3U CubeSat standard, which is currently being designed and built at the Surrey Space Centre, University of Surrey. CubeSail will have a total mass of around 3 kg and will deploy a 5 × 5 m sail in low Earth orbit. The primary aim of the mission is to demonstrate the concept of solar sailing and end-of-life de-orbiting using the sail membrane as a drag-sail. The spacecraft will have a compact 3-axis stabilised attitude control system, which uses three magnetic torquers aligned with the spacecraft principle axis as well as a novel two-dimensional translation stage separating the spacecraft bus from the sail. CubeSail’s deployment mechanism consists of four novel booms and four-quadrant sail membranes. The proposed booms are made from tape-spring blades and will deploy the sail membrane from a 2U CubeSat standard structure. This paper presents a systems level overview of the CubeSat mission, focusing on the mission orbit and de-orbiting, in addition to the deployment, attitude control and the satellite bus.     

利用绳系太阳帆减缓小行星自转的技术研究

提出一种利用太阳帆绳系系统逐渐减小小行星自转速率的方法。在系绳长度不变的情况下,利用太阳帆受到的太阳光压力使其始终保持与小行星同步,避免了由于小行星自转而引起的系绳缠绕问题。通过控制太阳帆使系绳始终拉紧,系绳中的拉力便可以持续提供一个与小行星自转方向相反的力矩,从而减小其自转速率。仿真结果表明,面积10⁶ m²的太阳帆,经过约86天可将小行星的自转消除,验证了该方法的有效性。