Bulletin of the AAS • Vol. 52, Issue 3 (AAS236 abstracts) Science highlights of the Arecibo Observatory planetary radar program

A. K. Virkki1, F. C. Venditti1, S. E. Marshall1, D. C. Hickson1, L. F. Zambrano Marin1, P. A. Taylor2, E. G. Rivera-Valentin2

1Arecibo Observatory/University of Central Florida, Arecibo, PR, 2Lunar and Planetary Institute / USRA, Houston, TX

Published on: Jun 01, 2020 Updated on: Jul 15, 2020 License: Creative Commons Attribution 4.0 International License (CC-BY 4.0) Bulletin of the AAS • Vol. 52, Issue 3 (AAS236 abstracts) Science highlights of the Arecibo Observatory planetary radar program

We present recent and expected science highlights of the Arecibo Observatory’s planetary radar program from the last three years to 2022. The Arecibo Observatory in Puerto Rico is a key facility for post-discovery characterization of near- objects (NEOs) and for studies of celestial bodies from out to the icy of Saturn. The 2.38-GHz planetary radar system actively contributes to the investigation of physical and dynamical properties of NEOs by observing 80-120 NEOs annually, including potentially hazardous (PHAs), which are the priority targets of the fully NASA- funded planetary radar program. Planetary radar observations offer unparalleled imaging capabilities of NEOs that can directly reveal their shape, surface geology, spin, and binarity. Furthermore, radar data can provide clues to regolith’s physical properties at centimeter-to-decimeter size scales. Research highlights include observations in December of 2017 of 3200 Phaethon, which is linked to the Geminid meteor shower and will be JAXA’s DESTINY+ mission target, the equal- binary asteroid 2017 YE5 observed in June 2018, and the PHAs 163899 (2003 SD220) observed in

December 2018 and 68950 (2002 QF15) observed in May 2019. Also, the mission target asteroid (162173) Ryugu will be observed at Arecibo in November 2020, and the asteroid (99942) Apophis in March 2021, which is its closest approach to the Earth before the highly anticipated close approach in April 2029. The Arecibo planetary radar program will also support NASA’s upcoming Double Asteroid Redirection Test (DART) mission to the binary asteroid system (65803) Didymos, with the goal of testing the kinetic impact method on the secondary component of the system. In addition to physical characterization, Arecibo will play a crucial role measuring the change in the orbital parameters of the secondary component after the impact. Didymos will enter the telescope’s field of view starting on Oct 24th, 2022 and will be visible for several weeks.

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