REMORA - REndezvous Mission for Orbital Reconstruction of Asteroids: A fleet of Self-driven CubeSats for Tracking and Characterising Asteroids

截至2021年1月，我们的太阳系有24,797个已知的近地天体（neo），分为小行星（24,684）和彗星（113）。直径超过140米的小行星，其轨道穿过地球轨道，对我们的星球构成威胁，被归类为潜在危险小行星(PHAs) - 2,156个物体。2004年，在对小行星阿波菲斯（直径约350米）的轨道进行调查后发现，2029年与地球相撞的可能性很大，因此，准确预测pha轨道的必要性成为了一个严肃的问题。进一步的观察得出结论，阿波菲斯在2029年不再构成威胁，但它现在可能在2036年撞击地球。阿波菲斯突出了目前在精确预测小行星轨道及其潜在影响的观测方面的局限性。此外，仅在2013年，当一颗直径约20米的小行星在车里雅宾斯克（RU）造成约1600人受伤时，减少PHA才成为优先事项。由于这颗小行星的轨道位于地球白天的天空中，地面望远镜无法探测到它，因此没有向当地居民发出警告。车里雅宾斯克事件表明，相对较小的小行星的撞击可能构成重大威胁。鉴于此类事件可能在未来发生，有可能造成严重的人身伤害/生命损失，经济中断和物质破坏，下一代天基技术如何克服望远镜的局限性，系统地跟踪和表征pha ？remoa -小行星轨道重建的相会任务：一队用于跟踪和表征小行星的自驱动立方体卫星探索了一种新的任务理念，其灵感来自于remoa鱼（即立方体卫星，10x10x10厘米，每单位1.35千克）和鲨鱼（即目标小行星）之间的共生关系。就像䲟鱼附着在鲨鱼身上，利用鲨鱼作为食物和免费运输一样，一组标记小行星的立方体卫星将提供高精度的轨道测定。小行星是小型的（1 -100公里）、不活跃的、围绕太阳运行的天体。太阳和大行星的引力会改变它们的轨道，因此，如果没有精确的观测和跟踪，它们的运动是无法可靠地预测未来许多年（如阿波菲斯）的。此外，在天空向阳轨道运行的小行星不太可能被发现（例如车里雅宾斯克）。因此，除非航天器与PHA会合并对其进行分析，否则无法精确确定PHA的物理特性和轨道。目前还没有现成的技术被证明能有效地改变小行星的轨道。在开发用于偏转PHA轨道的减缓设计之前，充分表征PHA是至关重要的。REMORA将填补当前小行星观测的局限性与未来缓解技术设计之间的“空白”，以应对迫在眉睫的PHA威胁。向太阳系内的小行星发射一组空间传感器——立方体卫星（CubeSats），以便与小行星会合，这样就可以永久、准确地跟踪关键轨道，我们也将在保卫地球方面向前迈进一步。此外，小行星富含水，这是支持人类太空飞行、实现太空建设和降低太空飞行成本的关键因素。事实上，水对于维持生命、保护宇航员安全的辐射屏蔽以及在太空中制造火箭燃料的氧和氢都是必不可少的。从长远来看，小行星资源的解锁将带动小行星采矿业的发展。最终，REMORA将为立方体卫星的机载算法（即NEAR工具）奠定基础，该算法将能够在没有地面支持的情况下执行自己的任务，从而降低运行深空计划的成本，并实现灵活、大规模和多任务架构（即舰队）。

As of January 2021, our solar system is populated by 24,797 known Near-Earth Objects (NEOs) classified as asteroids (24,684) and comets (113). Asteroids over 140-meter diameter whose trajectories cross the Earth's orbit, represent a threat for our planet and are classified as Potentially Hazardous Asteroids (PHAs) - 2,156 objects. The need to accurately predict the orbit of PHAs emerged as a serious issue in 2004 when investigations into the trajectory of the asteroid Apophis (~350-meter diameter) revealed a high impact probability with Earth in 2029. Further observations concluded that Apophis no longer posed a risk in 2029 but it could now impact the Earth in 2036. Apophis serves to highlight the current limitations in observations to accurately predict asteroid orbits and their potential impacts. Moreover, PHA mitigation became a priority only in 2013 when an asteroid of ~20-meter diameter caused approximately 1,600 injuries in Chelyabinsk (RU). As the asteroid's trajectory placed it in the Earth's daytime sky, it was undetected by ground-based telescopes, therefore no warning was given to the local population. The Chelyabinsk incident revealed that impacts of relatively small asteroids can pose a significant threat. Given that such events could occur in the future, with the potential to cause severe injuries/loss of life, economic disruption, and material damage, how can the next generation of space-based technology overcome the limitations of telescopes to systematically track and characterise PHAs?REMORA - REndezvous Mission for Orbital Reconstruction of Asteroids: A fleet of Self-driven CubeSats for Tracking and Characterising Asteroids explores a new mission idea, inspired by the symbiotic relationship between remora fish (i.e., CubeSats, 10x10x10 cm and 1.35 kg per unit) and sharks (i.e., target asteroids). As remoras attach to sharks using them for food and free transportation, similarly, a fleet of CubeSats tagging asteroids will provide high accuracy in orbital determination. Asteroids are, small (1m-100km), inactive, celestial bodies orbiting the Sun. The gravitational forces of the Sun and larger planets alter their orbits, and thus, their motion is not reliably predictable many years into the future (e.g., Apophis) without precise observations and tracking. Moreover, asteroids who orbit in the day-side of the sky are less likely to be discovered (e.g., Chelyabinsk). Therefore, a PHA's physical characteristics and orbit cannot be precisely determined unless a spacecraft rendezvous with it and analyses the asteroid. There is a lack of readily available technology proven to be effective in altering an asteroid's orbit. Before mitigation designs are developed for deflecting a PHA's orbit, it is vitally important to characterise PHAs sufficiently.REMORA will fill the 'gaps' between the limitation of current asteroid observations and the design of future mitigation techniques in response to an imminent PHA threat. Sending a fleet of space sensors, CubeSats, throughout the solar system to rendezvous with asteroids will allow for key orbits to be permanently and accurately tracked and we will move a step forward in defending our planet. Moreover, asteroids are rich in water, a key element for supporting human spaceflight and for enabling in-space construction and reducing costs in spaceflight. Indeed, water is essential for life support, radiation shielding for astronaut safety and in-space manufacturing of rocket fuel for oxygen and hydrogen. In the long-term, unlocking asteroid resources will lead to the development of the asteroid mining industry. Ultimately, REMORA will lay the foundation for a CubeSat's onboard algorithm (i.e., NEAR tool) that will be capable of executing their own mission without ground support - reducing the costs for running deep space programs and enabling flexible, large-scale, and multi-mission architecture (i.e., a fleet).