Electric Solar Wind Sail Pole Sitter Spacecraft

电动太阳风帆极坐航天器提案摘要传统航天器能力的一个主要限制是它们所能携带的燃料数量有限。轨迹通常是弹道，通过短时间推进器爆炸或重力辅助进行修改。然而，太阳是一个无限推力的来源，如果适当地利用它，可以让航天器执行传统航天器无法完成的操作，例如完全脱离黄道平面的“轨道”。其中之一是用动力和太阳力（由太阳光子通量或太阳等离子体通量——太阳风提供）平衡太阳和地球的引力，这样航天器就可以在地球两极上方的固定位置悬停。这被称为“极化”轨道。设计用来利用太阳风的一种航天器是电帆航天器（e-sail），它由一个中心枢纽组成，从中心枢纽辐射出一些（大约80条）长绳（大约20公里），这些绳都带着很高的正电位，以便与太阳风的质子发生反应，提供推力。使用电子帆的聚脂器的想法是一个令人兴奋的新研究领域，尽管如此，它具有非常实际的潜在应用。一个例子是北方通讯。在纬度60度以上的地球同步卫星对通信的价值有限，因此，迄今为止，在高度偏心轨道上运行的昂贵的航天器星座被视为解决方案。最近的加拿大极地通信和天气（PCW）项目正是这种类型的，当它对两颗卫星的成本估算成为天文数字时，它被搁置了。另一方面，极地卫星可以作为通信中继卫星在极地上空盘旋，也可以从一个相对固定的点监测天气。偏振仪作为遥感平台也有许多优点，但最重要的应用可能是监测太阳天气和地磁风暴预警。太阳耀斑和物质抛射的结果，这些事件摧毁卫星，扰乱通信，破坏电网，造成巨大的经济损失和生命威胁。Ace和SOHO航天器，目前我们最好的太阳天气监测手段，在太阳-地球L1，提供30到60分钟的这些事件预警。polestter的朝向太阳的距离可以是这些航天器的两倍，从而使我们在地球上的预警时间增加一倍。本研究的最终目标是电子帆极座飞行器的技术演示飞行，但首先需要了解这种类型的航天器在这种轨道上的动力学和控制。这一提议的电子帆杆座以前从未被考虑过。这个提议的目标是：表征太阳等离子体对电子帆的推力；研究电帆极化轨道的稳定性和可控性；设计一种控制系统，使电子帆航天器悬停在地球两极上方的固定点上；设计一种保持电子帆航天器结构完整性的方法；并研究了一项全新的技术，光子腔推力器，它将使用激光压力来控制电子帆的结构。

Electric Solar Wind Sail Pole SItter Spacecraft Proposal SummaryA major constraint on the capabilities of conventional spacecraft is the limited amount of fuel they can carry. Trajectories are generally ballistic with modifications by means of short thruster bursts or gravity assists. However, the Sun is a source of unlimited thrust which if appropriately harnessed can allow spacecraft to perform manoeuvres impossible for conventional spacecraft, such as "orbits" entirely out of the plane of the ecliptic. One of these balances the gravity of the Sun and the Earth with dynamic and solar forces, (provided by either the solar photon flux or the solar plasma flux - the solar wind) so that the spacecraft can hover in a fixed position above one of the Earth's poles. This is called a "polesitter" orbit. One type of spacecraft designed to use the solar wind is the electric sail spacecraft (e-sail) consisting of a central hub from which radiate a number (approx 80) of long tethers (approx 20 km) all charged to a high positive potential so as to react against the protons of the solar wind to provide thrust. The whole structure is spun to provide gyroscopic stiffnessThe idea of a polesitter using an e-sail is an exciting new research area which nevertheless has very practical potential applications. One example is northern communications. Above 60 degrees latitude geostationary satellites are of limited value for communications, with the result that expensive constellations of spacecraft in highly eccentric orbits have been seen as the solution thus far. The recent Canadian Polar Communications and Weather (PCW) program of exactly this type, was put on hold when its cost estimates for just two satellites became astronomical. A polesitter, on the other hand, could just hover above the pole as a communications relay satellite and could also monitor the weather from a relatively fixed point. A polesitter would also have many advantages as a remote sensing platform, but perhaps the most significant application would be for monitoring solar weather and warning of geomagnetic storms. The result of solar flares and mass ejections, these events destroy satellites, disrupt communications and knock out power grids at great financial cost and threat to lives. The Ace and SOHO spacecraft, currently our best means of solar weather monitoring, are at Sun-Earth L1, providing 30 to 60 minutes of warning of these events. A polesitter could be parked twice as far sunward as these spacecraft, thus doubling the warning time for us on the Earth.The ultimate objective of this research is a technology demonstration flight of an e-sail pole sitter, but it is necessary first to understand the dynamics and control of this type of spacecraft in such orbits. The e-sail pole sitter of this proposal has never before been considered.The goals of this proposal then are: to characterize the solar plasma thrust on an e-sail; to investigate stability and controllability of e-sail polesitter orbits; to design a control system to hover an e-sail spacecraft at a fixed point above one of the Earth's poles; to design a method to maintain the structural integrity of an e-sail spacecraft; and to investigate a radical new technology, the photonic cavity thruster, which would use laser light pressure for structural control of an e-sail.