Electric Solar Wind Sail Pole Sitter Spacecraft

电动太阳能风帆极保航天器提案摘要 传统航天器能力的一个主要限制是它们可以携带的燃料数量有限。弹道通常是弹道的，并通过短推进器爆发或重力辅助进行修改。然而，太阳是无限推力的来源，如果利用得当，可以让航天器执行传统航天器不可能完成的机动，例如完全脱离黄道平面的“轨道”。其中之一通过动态力和太阳力平衡太阳和地球的重力（由太阳光子通量或太阳等离子体通量 - 太阳风提供），以便航天器可以悬停在地球两极之一上方的固定位置。这被称为“极化者”轨道。 一种设计利用太阳风的航天器是电帆航天器（e-sail），它由一个中心枢纽组成，从该中心枢纽辐射出许多（约 80 条）长系绳（约 20 公里），所有系绳均充电至高正电势，以便与太阳风的质子发生反应以提供推力。整个结构旋转以提供陀螺刚度 使用电子帆的极座器的想法是一个令人兴奋的新研究领域，但具有非常实际的潜在应用。北方通讯就是一个例子。纬度 60 度以上的地球静止卫星对于通信的价值有限，因此迄今为止，昂贵的高偏心轨道航天器星座一直被视为解决方案。最近的加拿大极地通信和天气（PCW）计划正是这种类型，但由于两颗卫星的成本估算变得天文数字而被搁置。另一方面，极点发射者可以作为通信中继卫星悬停在极点上方，还可以从相对固定的点监测天气。作为遥感平台，极点定位器还具有许多优势，但最重要的应用可能是监测太阳天气和地磁风暴预警。由于太阳耀斑和大规模抛射，这些事件会摧毁卫星、扰乱通信并破坏电网，造成巨大的经济损失并威胁生命。 Ace 和 SOHO 航天器是目前我们最好的太阳天气监测手段，位于日地 L1 级，可为这些事件提供 30 至 60 分钟的预警。极客可以停在距离太阳两倍远的地方，从而使我们在地球上的预警时间加倍。 这项研究的最终目标是电子帆极座器的技术演示飞行，但首先有必要了解此类航天器在此类轨道上的动力学和控制。此前从未考虑过该提案中的电动帆杆选择。 该提案的目标是： 描述电子帆上的太阳等离子体推力的特征；研究电子帆极定位器轨道的稳定性和可控性；设计一种控制系统，使电动帆航天器悬停在地球两极上方的固定点；设计一种保持电子帆航天器结构完整性的方法；并研究一项激进的新技术，即光子腔推进器，该技术将使用激光压力来控制电子帆的结构。

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.