Electric Solar Wind Sail Pole Sitter Spacecraft

传统航天器能力的一个主要制约因素是它们所能携带的燃料量有限。弹道通常是弹道式的，并通过短时间的推进器爆发或重力辅助进行修改。然而，太阳是一个无限推力的来源，如果加以适当利用，可以使航天器进行常规航天器无法进行的机动，例如完全脱离黄道平面的“轨道”。其中一个平衡太阳和地球的重力与动态和太阳力（由太阳光子通量或太阳等离子体通量-太阳风提供），以便航天器可以在地球两极之一上方的固定位置悬停。这就是所谓的“polesitter”轨道。设计用于利用太阳风的一种航天器是电帆航天器（e-sail），它由一个中心毂组成，从中心毂辐射出许多（约80个）长系绳（约20公里），所有系绳都被充电到高正电位，以便与太阳风的质子发生反应，提供推力。整个结构是旋转提供陀螺刚度的想法polesitter使用电子帆是一个令人兴奋的新的研究领域，但有非常实际的潜在应用。北方通信就是一个例子。60度纬度以上的地球静止卫星对通信的价值有限，因此，迄今为止，高偏心轨道上昂贵的航天器星座一直被视为解决办法。最近的加拿大极地通信和天气（PCW）计划正是这种类型的，被搁置时，其成本估计只有两颗卫星成为天文数字。另一方面，测极仪可以作为通信中继卫星悬停在极点上方，也可以从相对固定的点监测天气。作为一个遥感平台，极测仪也有许多优点，但最重要的应用可能是监测太阳天气和地磁风暴警报。这些事件是太阳耀斑和物质抛射的结果，它们摧毁卫星，中断通信，摧毁电网，造成巨大的经济损失和生命威胁。Ace和SOHO航天器目前是我们监测太阳天气的最佳手段，位于日地L1，提供30至60分钟的这些事件警报。一个极地探测器可以停在两倍于这些航天器的向阳方向，从而使我们在地球上的预警时间增加一倍。这项研究的最终目标是一个电子帆极座的技术演示飞行，但首先有必要了解这种类型的航天器在这样的轨道上的动力学和控制。这一建议的电子帆杆位以前从未被考虑过。该建议的目标是：确定电子帆上太阳等离子体推力的特征;研究电子帆极坐标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之一上方的固定点上;设计一种保持电子帆航天器结构完整性的方法;并研究一种全新的技术，光子腔推进器，它将利用激光压力对电子帆进行结构控制。

Electric Solar Wind Sail Pole SItter Spacecraft Proposal Summary A 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 stiffness The 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.