The separation between asteroids and comets has become less clear with the discovery of a small group of asteroids that display comet-like dust activity. While the activity is attributed to…

This federal contract award is a grant from the National Aeronautics and Space Administration (NASA) Shared Services Center to the Lowell Observatory, a private non-profit research institution located in Flagstaff, Arizona. The $101,002.95 grant is for research related to the study of near-Earth asteroids (NEAs) and comets. Specifically, the research aims to characterize the physical properties and potential activity of dormant comets and near-Sun asteroids, which have important implications for comet evolution, the origins of terrestrial water and volatiles, and the future resource utilization of NEAs. The grant does not have a set-aside designation and was awarded on August 31, 2018, with a completion date of May 5, 2021. As a prime grantee under NASA's Science and Astrophysics programs, the Lowell Observatory has a history of conducting research to advance the planetary sciences and support NASA's goals of understanding solar system bodies.

The separation between asteroids and comets has become less clear with the discovery of a small group of asteroids that display comet-like dust activity. While the activity is attributed to different mechanisms, some objects seem to activate close to the sun. Near-earth asteroids (NEAS) come close to the earth and the sun, constituting a natural laboratory for the study of thermally induced activity. Two NEA sub-populations are especially suspected of being potentially active: dormant comets and near-sun asteroids. Dormant comets are cometary nuclei that have depleted their near-surface ICE reservoirs and do not show activity in the form of a coma or a tail. In contrast to most asteroids, dormant comets move on comet-like orbits and share the physical surface properties of cometary nuclei. Examples of dormant comets that have displayed comet-like activity suggest that at least some dormant comets are still capable of harboring ices. The existence of ices in the NEA population has important implications for comet evolution models, the origin of terrestrial water and other volatiles, and the future resource utilization of NEAS. Near-sun asteroids are NEAS with extremely low perihelion distances. A recent study (granvik ET AL. 2016, nature, 530) found a lack of near-sun asteroids compared to model simulations of the NEA population. This lack is attributed to the disruption of asteroids close to the sun, which is thought to be linked to their sizes and compositions. Characterizing the physical properties of near-sun asteroids as well as the search for activity in them will provide important constraints on the nature of the disruption process, the origin of meteor streams, and the zodiacal dust.