Heating of Small Solar System Body Materials

Abstract

Small bodies, including asteroid and comet populations, are leftover material from planet formation 4.6 Gya. Near-Earth objects, asteroids and comets with closest approaches to the sun of <1.3 au, are a convenient source of extraterrestrial materials, including leftovers from Solar System formation. By studying the heating of near-Earth asteroid analogue material in carbonaceous chondrite meteorites, and gas and dust interactions between the nucleus and inner coma of a Jupiter-family comet, we can learn about composition and history of these bodies. The thermal response of elements in meteorites is important for quantifying the degree of thermal isolation necessary for asteroid sample return missions, in particular the OSIRIS-REx mission to asteroid (101955) Bennu; understanding the effects thermal processing has on an asteroid surface and "rock comets" such as (3200) Phaethon; and future in situ resource utilization of asteroids and other planetary bodies for water mining. Studying materials released from short-period Jupiter-family comets (JFCs) as seen in their inner comæ, the envelope of gas and dust forming as the comet approaches the Sun, provides an improved understanding of the evolution and origin of these objects. In 2017, a 1.2-km JFC, 45P/Honda-Mrkos-Pajdušáková, passed 0.08 au from Earth, presenting an excellent opportunity to observe this object at close range to study its inner coma, resolving gas and dust structures and characterizing the properties of large (>2 cm) grains leaving the nucleus. Detailed measurements from ground-based visible-wavelength and radar observations were made of 45P’s inner coma, a region typically too far away to obtain adequate spatial resolution, and/or typically obscured by photodissociation products of the volatile species targeted by this work. Connecting dust grain observations from continuous wave radar with visible imaging of volatile species and smaller dust particles, as well as radar-derived shape models of nuclei, allows for a more holistic understanding of processes occurring in the inner comæ of JFCs.