We critically examine what hyperactivity on a comet entails, fully develop the A’Hearn Model for Hyperactivity based on the analyses of data collected for the Deep Impact encounter of comet 103P/Hartley 2, describe manifestations of hyperactivity suggested on many, if not all, comets, and give implications of hyperactivity for future cometary exploration. The A’Hearn model requires a highly volatile ice reservoir within a comet to undergo sublimation, escape the nucleus, and drive out less volatile ices along its path to the surface. Once in the coma, the less volatile ice eventually sublimates, creating a secondary source of that gas in the coma, which is generally displaced anti-sunward and not distributed symmetrically about the nucleus. The secondary source of gas increases the total production of the less volatile species in the coma, sometimes well above that expected if the total surface was undergoing sublimation. We argue that based on the simple assumptions of the A’Hearn model and the fact that several comets display one or more of the characteristics of hyperactivity detailed here, it is probable that nearly all comets experience some degree of hyperactivity. Of significance, the ice that is brought from deep within the nucleus into the coma via the process described by the A’Hearn model is the least thermally altered and is thus the most pristine ice in the comet. Therefore, it behooves future mission teams to consider cryogenically sampling coma ice, rather than or in addition to attempting a direct nucleus sample, for a better understanding of the unaltered ices and conditions present in the protoplanetary disk.

我们批判性地研究了彗星上的多动症意味着什么，根据对彗星 103P/Hartley 2 的深度撞击遭遇收集的数据的分析，充分开发了 A'Hearn 多动症模型，描述了许多（如果不是全部）建议的多动症表现，彗星，并为未来的彗星探索提供多动症的含义。A'Hearn 模型需要彗星内的高度挥发性冰库进行升华，逃离原子核，并沿其通往表面的路径驱逐挥发性较低的冰。一旦进入昏迷状态，挥发性较低的冰最终会升华，从而在昏迷中形成该气体的次要来源，该气体通常逆向移动，而不是围绕原子核对称分布。二级气体源增加了昏迷中挥发性较小的物质的总产量，如果整个表面正在升华，有时远高于预期。我们认为，基于 A'Hearn 模型的简单假设以及多颗彗星表现出此处详述的一种或多种多动特征这一事实，几乎所有彗星都可能经历某种程度的多动。重要的是，通过 A'Hearn 模型描述的过程从原子核深处进入昏迷的冰是热变化最少的，因此是彗星中最原始的冰。因此，未来的任务团队应该考虑对昏迷冰进行低温采样，而不是尝试直接核样本，或者除了尝试直接核样本之外，以便更好地了解原行星盘中存在的未改变的冰和条件。