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

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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.