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Allowable Initial Relative Velocity of a Net to Contact and Capture Space Debris 网接触和捕获空间碎片的允许初始相对速度
Andry Renaldy PANDIE, Hirohisa KOJIMA
The escalating presence of space debris is becoming increasingly problematic due to the ensuing potential of damage to active spacecraft if a collision were to occur. The tether net has emerged as a possible solution for the capture of such debris. Although extensive studies have been conducted on the net's performance, the influence of initial debris velocity and net ejection on the tether net's interaction with and capture of debris has not been confirmed. The primary aim of this study is to investigate the net's behavior when it interacts with space debris moving at a range of velocities. The objective is to ascertain the permissible initial relative speed of the net necessary to facilitate successful contact and subsequent capture of the debris. This determination takes into account the initial velocities of both the ejection of the net and the debris. The results reveal that successful interaction between the net and the debris is influenced by several variables. These include the initial velocity of the debris relative to the net ejection system, the furthest distance from the net to the ejection system when the net commences contraction, the speed at which the net is ejected, and the direction of debris motion.
空间碎片的不断增加正成为越来越严重的问题,因为一旦发生碰撞,可能会损坏正在运行的航天器。绳网已成为捕获此类碎片的一种可能解决方案。虽然对网的性能进行了广泛的研究,但碎片初始速度和网弹射对系绳网与碎片相互作用和捕获碎片的影响尚未得到证实。本研究的主要目的是研究网在与一定速度的空间碎片相互作用时的行为。目的是确定网的允许初始相对速度,以便于成功接触和随后捕获碎片。这一决定考虑了网和碎片弹射的初始速度。结果表明,网和碎片之间的成功相互作用受到几个变量的影响。这些参数包括碎片相对于网弹射系统的初始速度、网开始收缩时从网到弹射系统的最远距离、网弹射的速度以及碎片运动的方向。
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引用次数: 0
A Smoothed Eclipse Model for Solar Electric Propulsion Trajectory Optimization 一种用于太阳能电力推进轨迹优化的光滑日食模型
Jonathan D. Aziz, D. Scheeres, Jeffrey Stuart Parker, J. Englander
Solar electric propulsion (SEP) is the dominant design option for employing low-thrust propulsion on a space mission. Spacecraft solar arrays power the SEP system but are subject to blackout periods during solar eclipse conditions. Discontinuity in power available to the spacecraft must be accounted for in trajectory optimization, but gradient-based methods require a differentiable power model. This work presents a power model that smooths the eclipse transition from total eclipse to total sunlight with a logistic function. Example trajectories are computed with differential dynamic programming, a second-order gradient-based method.
太阳能电力推进(SEP)是在航天任务中采用低推力推进的主要设计方案。航天器太阳能阵列为SEP系统供电,但在日食条件下会受到停电期的影响。在轨迹优化中必须考虑航天器可用功率的不连续性,但基于梯度的方法需要一个可微功率模型。本文提出了一个用逻辑函数平滑从日全食到日全食过渡的功率模型。用微分动态规划(一种基于二阶梯度的方法)计算示例轨迹。
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引用次数: 18
Application of Machine Learning to the Particle Identification of GAPS 机器学习在间隙粒子识别中的应用
T. Wada, H. Fuke, Y. Shimizu, T. Yoshida
GAPS is an international balloon-borne project that contributes to solving the dark-matter mystery through a highly sensitive survey of cosmic-ray antiparticles, especially undiscovered antideuterons. To achieve a sufficient sensitivity to rare antideuterons, a novel particle identification method based on exotic atom capture and decay has been developed. In parallel to utilizing this unique event signature in a conventional likelihood-based event identification scheme, we have begun investigating a complementary approach using a machine learning technique. In this new approach, a deep-learning package is trained on a large amount of input data from simulated antiparticle events through a multi-layered neural network. By applying this unbiased approach, we expect to mine unknown patterns and give feedback to the conventional method. In this paper, we report results from exploratory investigations that illustrate the promise of this new approach.
gap是一个国际气球运载项目,通过对宇宙射线反粒子,特别是未发现的反氘核进行高度敏感的调查,有助于解开暗物质之谜。为了获得对稀有反氘核足够的灵敏度,提出了一种基于外来原子捕获和衰变的新型粒子识别方法。在传统的基于似然的事件识别方案中利用这种独特的事件签名的同时,我们已经开始研究一种使用机器学习技术的补充方法。在这种新方法中,深度学习包通过多层神经网络对来自模拟反粒子事件的大量输入数据进行训练。通过应用这种无偏方法,我们期望挖掘未知模式并对传统方法进行反馈。在本文中,我们报告了探索性调查的结果,说明了这种新方法的前景。
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引用次数: 2
Observer-Based Disturbance Estimation for a Spacecraft Inertial Pointing Using Magnetic Torquers 基于观测器的航天器惯性指向磁力矩干扰估计
Jongbum Kim, H. Bang
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引用次数: 1
Investigation into Star Tracker Algorithms using Smartphones with Application to High-Precision Pointing CubeSats 基于智能手机的星跟踪器算法及其在高精度指向立方体卫星上的应用研究
Joshua J. R. Critchley-Marrows, Xiaofeng Wu
For all common satellite attitude determination sensors, star trackers provide the most accurate measurement. However, these devices can be both large and expensive, and for some CubeSat applications it would not be suitable. Star trackers have in the past been successfully made for CubeSats. This paper investigates star tracker algorithms, implemented with a smartphone, so it may be used for testing attitude determination on a CubeSat. By testing through a proposed implementation, star centroids should be found by the moment method, stars should be identified by planar triangles, and QUEST should be used for attitude estimation. Smeared star images should be avoided and blurred images provide greater accuracy. Using these techniques, a star tracker using a smartphone may be constructed for attitude determination testing and software development, applied in the lost-in-space situation. This may be applied to QKD CubeSats, which require an attitude precision below 0.01
对于所有常见的卫星姿态确定传感器,星跟踪器提供最精确的测量。然而,这些设备既大又贵,对于一些立方体卫星应用来说,它并不合适。过去曾成功地为立方体卫星制造过恒星追踪器。本文研究了用智能手机实现的星跟踪器算法,因此它可以用于立方体卫星的姿态确定测试。通过所提实现的测试,采用矩量法寻找星质心,采用平面三角形识别星,采用QUEST进行姿态估计。应避免模糊的星图,模糊的图像提供更高的精度。利用这些技术,可以构建一个使用智能手机的星跟踪器,用于姿态确定测试和软件开发,应用于迷失空间的情况。这可能适用于要求姿态精度低于0.01的QKD立方体卫星
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引用次数: 3
Computational Study on Finned Reusable Rocket Aerodynamics during Turnover 翅片可重复使用火箭周转过程空气动力学计算研究
Takuya Aogaki, K. Kitamura, S. Nonaka
The development of a fully reusable vertical-takeoff-and-vertical-landing (VTVL) rocket is indispensable for reducing space transportation costs. However, there are many technical issues associated with such vehicles, such as turnover maneuvers during return flight where the pitching moment plays a key role. It is known that aerodynamic characteristics can be controlled by installing aerodynamic devices, but the relationship between the aerodynamic characteristics and the flowfields has not been explored. To clarify this relationship using computational fluid dynamics (CFD), we investigated these flowfields and aerodynamic characteristics, in the case where we install such devices (fins) in the nose part of a reusable rocket. We found that vortices form downstream of the aerodynamic devices. For angles of attack between 0 and 90 degrees (in which the fins are located in the upstream portion), these vortices significantly affect the surface pressure on the rocket and increase the pitching moment. On the other hand, for AOAs between 90 to 180 degrees (in which the fins are in the downstream portion), the effect of these vortices on the on-surface pressure is negligible, and only vortices formed near the surface of the fins increase the pitching moment.
研制完全可重复使用的垂直起降(VTVL)火箭对于降低航天运输成本是必不可少的。然而,这种飞行器存在许多技术问题,如返航时的翻转机动,其中俯仰力矩起着关键作用。众所周知,气动特性可以通过安装气动装置来控制,但气动特性与流场之间的关系尚未得到探讨。为了利用计算流体动力学(CFD)澄清这种关系,我们研究了这些流场和空气动力学特性,在可重复使用的火箭的前端部分安装了这些装置(鳍)。我们发现涡流在气动装置的下游形成。对于0到90度的迎角(其中翼位于上游部分),这些涡流显著影响了火箭的表面压力并增加了俯仰力矩。另一方面,对于90 ~ 180度的aoa(翼在下游),这些涡对表面压力的影响可以忽略不计,只有在翼面附近形成的涡才会增加俯仰力矩。
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引用次数: 0
Roll Moment Characteristics of Supersonic Flight Vehicle Equipped with Asymmetric Protuberance 非对称凸起超声速飞行器的滚转力矩特性
T. Harada, K. Kitamura, S. Nonaka
Most of flight vehicles have various protuberant devices on their surfaces, but asymmetry in their positioning with respect to the body axis can affect aerodynamic characteristics of vehicles, particularly roll moment. Thus, it is important in rocket development to clarify the effects of the protuberances on the vehicle aerodynamic characteristics. In this study, as a basic research, we systematically investigated such effects using CFD, by changing the positions of a protuberance. As a result, the roll moment increased nearly linearly with angle of attack (= α ), but its trend was different in protuberance locations, particularly when arranged near the center-of-gravity. In positioning there at α = 20 °, the wake vortex center moved farther away from protuberance compared with α = 15 °, then the pressure decline at its wake side was suppressed, and thus, the pressure difference between its upstream and downstream sides became smaller. As a consequence, the roll moment did not arise linearly, but decreased at α = 20 °.
大多数飞行器表面都有各种凸起装置,但其位置相对于体轴的不对称会影响飞行器的气动特性,尤其是滚转力矩。因此,研究凸起对飞行器气动特性的影响对火箭研制具有重要意义。在本研究中,作为一项基础研究,我们使用CFD系统地研究了这种影响,通过改变凸起的位置。结果表明,滚转力矩随迎角(= α)的增加几乎呈线性增加,但在凸起位置,特别是在重心附近,其变化趋势不同。在α = 20°位置时,尾迹涡中心相对于α = 15°位置远离凸起,尾迹侧的压力下降得到抑制,因此其上、下游侧的压差变小。结果表明,横摇力矩在α = 20°时减小,而不是线性增加。
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引用次数: 0
Numerical Analysis on Reusable Rocket Aerodynamics with Reduced-Yaw-Force Configurations 减偏航力配置下可重复使用火箭空气动力学数值分析
Ayano Inatomi, K. Kitamura, S. Nonaka
It is known that aerodynamic characteristics of a slender body vary substantially at high angles-of-attack (AoAs), and then, will have strong impacts on its flight. For, example, the yaw force makes flight unstable. In this study, we investigated the relation between the yaw force and the configuration, and details of flowfield around the slender-bodied-vehicle numerically. The configuration consisting of “nose cone” and “square aftbody” parts was employed as the baseline, and then, compared with other three configurations having different fineness ratios. According to our computed results, in the case of 50 degrees of AoA, the longer the model became, the more asymmetry appeared: yaw force and asymmetry were found to be attributed not only to the length of the body, but also to the nose bluntness. On the contrary, in the case of 140 degrees, the shorter the model became, the more asymmetry appeared. Furthermore, the large nose bluntness increased CY. Interestingly, this trend is totally opposite to that observed at 50 degrees. It had been considered that the large nose bluntness and the small fineness ratio can reduce asymmetry and CY, however, this study showed that it is not true in the case over 90 degrees, due to complex wake flow structure discovered in the present numerical simulations.
众所周知,细长机身在大迎角时的气动特性会发生很大的变化,从而对其飞行产生很大的影响。例如,偏航力使飞行不稳定。本文通过数值模拟的方法研究了细长体飞行器的横摆力与飞行器周围流场的结构和细节之间的关系。以“鼻锥”和“后体方形”组成的构型为基准,与其他三种不同细度比的构型进行比较。根据我们的计算结果,在AoA为50度的情况下,模型越长,出现的不对称性越大:发现偏航力和不对称性不仅归因于身体的长度,而且归因于鼻子的钝性。相反,在140度的情况下,模型越短,不对称越明显。此外,大鼻子的钝度增加了CY,有趣的是,这种趋势与50度的观察结果完全相反。以往认为,大的机头钝度和小的细度比可以降低不对称度和CY,但本研究表明,在超过90度的情况下,由于目前数值模拟中发现的复杂尾流结构,这种情况并不正确。
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引用次数: 2
Science Objectives of the Ganymede Laser Altimeter (GALA) for the JUICE Mission JUICE任务中木卫三激光高度计(GALA)的科学目标
J. Kimura, H. Hussmann, S. Kamata, Koji Matsumoto, J. Oberst, Gregor Steinbrugge, A. Stark, K. Gwinner, S. Oshigami, N. Namiki, K. Lingenauber, K. Enya, K. Kuramoto, S. Sasaki
Laser altimetry is a powerful tool for addressing the major objectives of planetary physics and geodesy, and have been applied in planetary explorations of the Moon, Mars, Mercury, and the asteroids Eros, and Itokawa. The JUpiter Icy Moons Explorer (JUICE), led by European Space Agency (ESA), has started development to explore the emergence of habitable worlds around gas giants. The Ganymede Laser Altimeter (GALA) will be the first laser altimeter for icy bodies, and will measure the shape and topography of the large icy moons of Jupiter, (globally for Ganymede, and using flyby ground-tracks for Europa and Callisto). Such information is crucial for understanding the formation of surface features and can tremendously improve our understanding of the icy tectonics. In addition, the GALA will infer the presence or absence of a subsurface ocean by measuring the tidal and rotational responses. Furthermore, it also improves the accuracy of gravity field measurements reflecting the interior structure, collaborating with the radio science experiment. In addition to range measurements, the signal strength and the waveform of the laser pulses reflected from the moon's surface contain information about surface reflectance at the laser wavelength and small scale roughness. Therefore we can infer the degrees of chemical and physical alterations, e.g., erosion, space weathering, compaction and deposition of exogenous materials, through GALA measurements without being affected by illumination conditions. JUICE spacecraft carries ten science payloads including GALA. They work closely together in a synergistic way with GALA being one of the key instruments for understanding the evolution of the icy satellites Ganymede, Europa, and Callisto.
激光测高是解决行星物理学和大地测量学主要目标的有力工具,已应用于月球、火星、水星、小行星爱神星和伊特川的行星探测。由欧洲航天局(ESA)领导的木星冰卫星探测器(JUICE)已经开始探索气态巨行星周围宜居世界的出现。Ganymede激光高度计(GALA)将是第一个用于冰体的激光高度计,并将测量木星的大型冰卫星的形状和地形(Ganymede是全球范围的,木卫二和木卫四使用飞越地面轨道)。这些信息对于了解地表特征的形成是至关重要的,并且可以极大地提高我们对冰构造的理解。此外,GALA将通过测量潮汐和旋转响应来推断地下海洋的存在与否。此外,它还与射电科学实验合作,提高了反映内部结构的重力场测量的精度。除了距离测量之外,从月球表面反射的激光脉冲的信号强度和波形包含了激光波长下的表面反射率和小尺度粗糙度的信息。因此,我们可以在不受光照条件影响的情况下,通过GALA测量来推断化学和物理变化的程度,例如侵蚀、空间风化、压实和外源物质的沉积。JUICE航天器携带包括GALA在内的10个科学有效载荷。它们以一种协同的方式密切合作,GALA是了解冰卫星Ganymede, Europa和Callisto演变的关键工具之一。
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引用次数: 9
Performance Model Simulation of Ganymede Laser Altimeter (GALA) for the JUICE Mission JUICE任务Ganymede激光高度计(GALA)性能模型仿真
H. Araki, K. Ishibashi, N. Namiki, H. Noda, Masanori Kobayashi, K. Enya, M. Ozaki, T. Mizuno, Yoshifumi Saito, K. Touhara, S. Oshigami, S. Kashima, J. Kimura, S. Kobayashi, G. Steinbruegge, A. Stark, C. Althaus, S. Togno, K. Lingenauber, H. Hussmann
In order to clarify the requirement on the interface conditions between modules of GALA, we developed the performance model of GALA based on the model of BELA (Bepi-Colombo Laser Altimeter). The performance model quantifies the link budget, range accuracy, albedo measurement accuracy, and probability of false detection (PFD). In the performance model, background noise from scattered sunlight from the Ganymede surface, surface and bulk dark currents of APD, noise floor of APD-TIA, shot noise, and speckle noise are taken into consideration. Black-body emission from the Ganymede surface is also taken into account while its influence to SNR is negligible compared with other noises. EMI noise shall be included after the evaluation of the verification model.
为了明确GALA各模块之间的接口条件要求,我们在Bepi-Colombo激光高度计(BELA)模型的基础上建立了GALA的性能模型。性能模型量化了链路预算、距离精度、反照率测量精度和误检概率(PFD)。在性能模型中,考虑了来自Ganymede表面散射太阳光的背景噪声、APD的表面和大体积暗电流、APD- tia的本底噪声、散粒噪声和散斑噪声。还考虑了木卫三表面的黑体发射,但与其他噪声相比,它对信噪比的影响可以忽略不计。在验证模型评估后,应包括EMI噪声。
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引用次数: 3
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TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN
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