Japan Geoscience Union Meeting 2019

Presentation information

[E] Oral

P (Space and Planetary Sciences ) » P-PS Planetary Sciences

[P-PS02] Regolith Science

Wed. May 29, 2019 3:30 PM - 5:00 PM A01 (TOKYO BAY MAKUHARI HALL)

convener:Koji Wada(Planetary Exploration Research Center, Chiba Institute of Technology), Akiko Nakamura(Graduate School of Science, Kobe University), Patrick Michel(Observatoire De La Cote D'Azur), Kevin John Walsh(Southwest Research Institute Boulder), Chairperson:Akiko Nakamura(Graduate School of Science, Kobe University)

3:30 PM - 3:45 PM

[PPS02-07] Impact Ejecta Environment of an Eccentric Asteroid: 3200 Phaethon

*Jamey Szalay1, Peter Pokorny2, Mihaly Horanyi3, Diego Janches2, Menelaos Sarantos2, Ralf Srama4 (1.Princeton University, 2.NASA/GSFC, 3.University of Colorado Boulder, 4.University of Stuttgart)

Keywords:Ejecta, Meteoroids, Regolith

Airless regolith bodies in the solar system are continually bombarded by meteoroids, modifying their surfaces and sustaining impact ejecta clouds. While large bodies like the Moon retain a significant fraction of ejected regolith, small asteroids shed this material into the interplanetary dust complex. Measurements of the lunar impact ejecta cloud found it was sustained by the known sporadic meteoroid sources. Here, we extend lunar ejecta measurements using a model of the meteoroid environment at 1 au to investigate the structure of an ejecta cloud at an eccentric airless body, asteroid 3200 Phaethon: the target of JAXA’s DESTINY+ mission.

Due to Phaethon's large eccentricity, Phaethon's peak ejecta density at 1 au is approximately 30 times higher compared to a body in a circular orbit at 1 au, largely due to enhanced ejecta production from meteoroids shed from Jupiter Family Comets. Such asymmetric ejecta production suggests Phaethon experiences significantly different meteoroid-specific space weathering processes than a body with a similar semi-major axis on a circular orbit. We estimate impact ejecta processes at Phaethon shed approximately 1 ton per year, which is not sufficient to appreciably contribute to the Geminids meteoroid complex, yet provides ample ejecta densities to measure with an in-situ dust detector aboard DESTINY+. These results suggest eccentric asteroids shed more material than those on near-circular orbits, and are suitable candidates for in-situ dust detection and chemical characterization due to their amplified asymmetric ejecta production.

In this presentation, we will summarize recent efforts to constrain the evolution and ejection of asteroid regolith for 3200 Phaethon. We will present predicted impact counts for a dust detector on close flybys of Phaethon in preparation for JAXA’s DESTINY+ mission and discuss how such measurements would provide critical insight into Phaethon’s origin and evolution in a manner unique to dust detection data.