Active Asteroids: Investigating Surface Structural Failure As a Source of Mass Loss

彗星和小行星是太阳系形成初期行星开始形成时的残余物。天文学家对它们很感兴趣，因为它们是构成行星的原始太阳系物质的代表。用望远镜观察到的一些小行星显示出通常只有在彗星上才能看到的尘埃流失活动。这些被称为“活跃小行星”，因为它们具有小行星的轨道和表面特征。这笔拨款将用于研究一颗绕其轴旋转的小行星是否会破坏其表面的尘埃或颗粒，这些尘埃或颗粒随后会以山体滑坡的方式从小行星表面脱落，从而产生观测到的类似彗星的活动。如果这个过程正在发生，它与小行星表面尘埃层中的物质类型有关。研究人员将通过实验，并将结果与望远镜观测结果进行比较，研究这种现象是如何发生的以及为什么会发生。该项目通过促进我们对用于创造太阳系早期行星的原始材料的组成和结构的理解来支持美国国家科学基金会的使命。首席研究员将招募并指导本科生在微重力研究中心实验室进行实验设计、制造、操作和数据分析，让他们亲身参与与太空相关的活动。活跃的小行星被归类为小行星，因为它们的动力学和光谱特征清楚地将它们与小行星分类类别联系在一起，但它们以颗粒损失的形式表现出活动，其速度在10^-2到10^-4 kg/s之间。该提议的中心假设是，小行星上的质量脱落可能是由于山体滑坡而发生的，这一过程与风化层（小行星表面的尘埃层）的材料和机械特性密切相关。拟议的工作将调查旋转破坏造成的风化层结构破坏，作为在许多这些小行星上观察到的尘埃喷射活动的可能起源，其他尘埃产生机制被排除在外。研究人员将实验室实验与风化层模拟、数值模拟和地面望远镜观测相结合。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Comets and asteroids are leftovers of the early stages of the creation of the Solar System when planets began to form. Astronomers are interested in them as they are objects representative of the primitive Solar System material that made the planets. Some asteroids have been observed with telescopes to show dust-loss activity normally seen only with comets. These are called "active asteroids", as they have orbits and surface characteristics of asteroids. This grant will study whether an asteroid spinning around its axis disrupts dust or particles on its surface, which are then shed off the surface of the asteroid in a landslide, creating the comet-like activity that is observed. If this process is happening, it is linked to the types of materials in the dust layer on the surface of the asteroid. The investigators will study how and why this is happening, using experiments and comparing the results with telescopic observations. This project supports the mission of the NSF by promoting our understanding of the composition and structure of primitive materials used to create the early planets in our Solar System. The lead investigator will recruit and guide undergraduate students for experiment design, manufacturing, operation, and data analysis in the Center for Microgravity Research laboratory, exposing them to hands-on space-related activities.The active asteroids are classified as asteroids because their dynamical and spectral characteristics clearly tie them to asteroid taxonomy classes, yet they display activity in the form of particle loss at rates ranging from 10^-2 to 10^-4 kg/s. The central hypothesis of this proposal is that mass shedding on small asteroids can occur due to landslides, a process intimately linked to the material and mechanical properties of regolith (the asteroid's surface dust layer). The proposed work will investigate regolith structural failure from rotational disruption as a possible origin for the dust ejection activity observed on a number of these asteroids, for which other dust production mechanisms were ruled out. The investigators combine laboratory experiments with regolith simulants, numerical simulations, and corroboration with ground-based telescopic observations.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.