Optimization of Low-Thrust Capture and Escape Trajectories
Optimization of Low-Thrust Capture and Escape Trajectories
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DOI：
10.2514/6.2005-4266
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发表时间：
2005-07
期刊：
影响因子：
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通讯作者：
Marco La Mantia;L. Casalino
中科院分区：
文献类型：
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作者：
Marco La Mantia;L. Casalino
在过去的几年里，电力推进(EP)被证明是太阳系探测的一个可行的选择，因为它可以提高探测器的性能和科学产量。与传统的化学发动机相比，推进剂消耗较低，而且由于长期使用电动发动机，可以实现连续的转向能力，这使得这种推进技术对星际轨道非常有吸引力。即使当EP用于行星际支路时，化学推进(CP)通常在离开时离开地球的影响范围，就像深空一号任务1和即将到来的黎明任务一样。相反，建议由EP执行火星到达时的捕获，以执行样本返回任务。3使用相同的高比冲EP系统执行不同的任务段的好处是显而易见的，至少如果可以容忍较长的跳闸时间的话。本文考虑了EP的两个潜在应用：从星际飞行返回的航天器的地球捕获和地球逃逸动作。结果可以很容易地扩展到其他行星的轨道。这类任务的优化是通过一种基于间接方法即最优控制理论的数值方法来实现的。两体问题的表述被认为足以对这一任务进行初步分析，特别是可以采用补丁二次曲线近似；因此，本文只考虑地球影响范围内的机动。这里的注意力集中在抓捕机动上，但将其扩展到逃跑案件是直截了当的。当指定接近速度时，寻求最大限度地减少从地球影响球边缘到所需低地球轨道(LEO)的低推力转移所需的总推进剂质量的策略。轨迹分为两部分。接近阶段也可能涉及弹道弧线，经过数值优化，将航天器插入高空圆形轨道。螺旋阶段将探测器带到最终的低轨轨道，并采用Edelbaum近似4(即考虑近圆形轨道)进行分析。这些部件之间的连接点被优化以最大化航天器的最终质量，从而最小化总推进剂质量。为简单起见，分析从二维问题开始，特别是与另一篇论文的比较，5在另一篇论文中，Kluever提出了一种优化地球捕获轨迹的类似方法。对问题陈述和结果陈述中的差异进行了动机和解释。研究了几种也涉及海岸弧线的策略，以及一些参数(即航天器的推力、比冲和初始速度)的影响。然后给出了三维捕获轨迹，并与二维问题的结果进行了比较。逃生动作终于被考虑了。
During the last years Electric Propulsion (EP) has proven to be a viable option for the Solar System exploration, as it can improve the performance of probes and their scientific yield. The lower propellant consumption, compared to traditional chemical motors, and the possibility of achieving continuous steering capabilities, related to the long use of electric engines, make this propulsion technology very attractive for interplanetary trajectories. Even when EP is used for the interplanetary leg, Chemical Propulsion (CP) is usually employed to leave the Earth’s sphere of influence upon departure, as in the case of the Deep Space 1 mission 1 and the upcoming DAWN mission. 2 EP has instead been proposed to perform the capture at Mars arrival for a sample return mission. 3 The benefit of using the same high-specific-impulse EP system to perform different mission legs is obvious, at least if the longer trip time can be tolerated. Two potential applications of EP are considered in the present paper: the Earth-capture of a spacecraft that returns from an interplanetary mission, and the Earth-escape maneuver. Results can easily be extended to trajectories around other planets. The optimization of this kind of missions is obtained by means of a numerical procedure, which is based on an indirect approach, i.e., the theory of optimal control. The two-body problem formulation is considered to be sufficient for the preliminary analysis of this mission and, in particular, the patched conic approximation can be adopted; therefore, only the maneuver inside the Earth’s sphere of influence is considered in the present paper. The attention is here focused on the capture maneuver, but the extension to the escape case is straightforward. The strategies, which minimize the total propellant mass required for the low-thrust transfer from the edge of the terrestrial sphere of influence to the desired low Earth orbit (LEO), are sought when the approaching velocity is assigned. The trajectories are split into two parts. The approach phase, which can involve also ballistic arcs, is numerically optimized and inserts the spacecraft into a high circular orbit. The spiral phase brings the probe to the final LEO and is analyzed by adopting Edelbaum’s approximation 4 (i.e., an almost circular trajectory is considered). The junction point between these parts is optimized to maximize the spacecraft final mass, thus minimizing the total propellant mass. For the sake of simplicity the analysis starts from the two-dimensional problem and, in particular, from the comparison with another paper, 5 where Kluever presented a similar approach for the optimization of Earth-capture trajectories. The differences in the statement of the problem and results are motivated and explained. Several strategies, which involve also coast arcs, are examined as well as the influence of some parameters (namely, the thrust, the specific impulse, and the initial velocity of the spacecraft). Threedimensional capture trajectories are then presented and compared with the results of the two-dimensional problem. Escape maneuvers are finally considered.