Abstract Space exploration has seen a growing number of asteroid missions being launched; mostly due to their scientific interest, but also on account of the potential impact threat and prospective valuable resources of their targets. Landing safely on the surface of an asteroid is one of the main technical challenges before obtaining in-situ observations and ground-truth data. Given the asteroid's extremely weak gravitational field, purely ballistic descent trajectories become a suitable option to reach its surface. However, this is still a very risky operation due to the limited knowledge of the object's physical characteristics. Hence, deploying a small lander is often a more conservative option than endangering the mothercraft itself, and thus a simple CubeSat may provide a low cost solution for asteroid exploration. However, for a CubeSat system to be able to safely land on the surface of an asteroid, a sufficient dissipation of energy must naturally occur at touchdown, or else the resultant bouncing may lead to high uncertainties on the final landing location, or even yield an escape trajectory. This paper describes the result of ESA Academy's Drop Your Thesis! 2018 (DYT2018) programme. DYT2018 carried out a microgravity experiment, led by Land3U team from the Astronautics and Space Engineering Course at Cranfield University, to provide additional data on the engineering constraints relevant to land a CubeSat on the surface of an asteroid. The experiment was performed in ZARM's Drop Tower, located in Bremen, during two Drop campaigns in November 2018 and February 2019. A total of 7 drops were completed, each providing 4.74 s of microgravity under vacuum environment. The experiment measured the coefficient of restitution of a 1U mock-up, equipped with a 4-kg mass, touching down on the simulated asteroid surface with an average velocity of 150 mm/s. Three successful drops measured a coefficient of restitution of 0.26 ± 0.03.

中文翻译：

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放弃你的论文！2018 年的结果：4.74 秒的微重力条件使未来的立方体卫星能够登陆小行星

摘要 太空探索已经看到越来越多的小行星任务被发射；主要是由于他们的科学兴趣，但也考虑到潜在的影响威胁和目标的潜在宝贵资源。在获得原位观测和地面实况数据之前，在小行星表面安全着陆是主要的技术挑战之一。鉴于小行星极弱的引力场，纯弹道下降轨迹成为到达其表面的合适选择。然而，由于对物体物理特性的了解有限，这仍然是一个非常危险的操作。因此，部署小型着陆器通常是比危及母舰本身更保守的选择，因此简单的立方体卫星可能为小行星探索提供低成本的解决方案。然而，CubeSat 系统要能够安全地降落在小行星表面，必须在着陆时自然发生足够的能量耗散，否则由此产生的弹跳可能导致最终降落位置的高度不确定性，甚至产生逃逸轨迹. 这篇论文描述了 ESA Academy 的 Drop Your Thesis! 的结果！2018 (DYT2018) 计划。DYT2018 进行了一项微重力实验，由克兰菲尔德大学航天与空间工程课程的 Land3U 团队领导，以提供有关将 CubeSat 降落在小行星表面相关的工程约束的额外数据。在 2018 年 11 月和 2019 年 2 月的两次 Drop 活动期间，该实验在位于不来梅的 ZARM 的 Drop Tower 中进行。 总共完成了 7 次跌落，每次提供 4 次。真空环境下微重力74秒。该实验测量了一个 1U 模型的恢复系数，该模型配备了 4 千克质量，以 150 毫米/秒的平均速度降落在模拟小行星表面上。三个成功的下降测得的恢复系数为 0.26 ± 0.03。