The expansion of debris flow shed from the primary of 65803 Didymos

Abstract

This paper investigates the plausible mass shedding from the surface of Didymos A, the primary of Near-Earth binary asteroid 65803 Didymos, and the subsequent orbital evolution of the shedding debris. Shedding conditions are derived semi-analytically. The unstable surface area on Didymos A is determined by combining the analyses and numeric results of SSDEM simulations. We show the observation-based model gives a highly unstable surface for Didymos A. In particular, most of the equatorial ridge is unattachable for cohesionless regolith, and an active region emerges along the ridge, in which extensive avalanches that cause surface mass shedding seem likely to happen. We track the ballistic motion of shedding debris from the unstable area. Month-long simulations show the diverse evolutions of sample particles with different sizes, due to the varying magnitude of solar radiation pressure. Statistics on the dynamical fates of shedding debris give clues on the current development of this binary system. Depending on the observation-based reference model, we find a vast majority of the shedding mass is finally transferred to Didymos B and thus leads to a cumulative growth. The cumulated mass may cause a spiralling-in motion of Didymos B, and the spiralling-in speed depends on the frequency and magnitude of mass shedding. A topography dependence of the mass shedding/transfer is also noticed that the cumulated mass mostly originates from highly elevated regions of the ridge areas. Long term it suggests that the shedding processes prefer to erode the bulges first and force the equatorial ridge to evolve into good roundness.

Regolith resurfacing and shedding on spinning spheroidal asteroids: Dependence on the surface mechanical properties

“…This means some of the mobilised regolith would be shed from the asteroid. The dynamics of the lofted material is governed by the gravitation (usually complex), shape (usually irregular), and surface mechanical properties of the asteroid, which can all contribute to its complex behavior (Sicardy et al 2019;Yu et al 2019). A full consideration of the complex nature of mass shedding is beyond the scope of this work.…”

Lifted particles from the fast spinning primary of the Near-Earth Asteroid (65803) Didymos

“…Campo Bagatin (2013) outlined the possibility of mass lifting as a general mechanism of regolith dispersal in fast spinning Near-Earth asteroids forming ''dusty'' environment around such bodies. Yu et al (2019) investigated mass shedding from the surface of the primary of (65 803) Didymos by a semi-analytical approach for shedding conditions. They determined unstable surface areas by combining the analyses and numerical results of SSDEM simulations.…”

Granular flow on a rotating and gravitating elliptical body

“…Recently, Yu et al. (2018, 2019) investigated mass shedding from the fast-spinning asteroid Didymos by analysing the motion of a particle on its surface. In spite of this rich body of work, a continuum analysis of granular flows in an extraterrestrial environment is uncommon.…”

“…Scheeres et al (2016Scheeres et al ( , 2019 studied the dynamical environment of the asteroids Bennu and Phobos using high-resolution shape models and derived the surface slope, lift-off speed, equilibrium points and Roche lobe. Recently, Yu et al (2018Yu et al ( , 2019 investigated mass shedding from the fast-spinning asteroid Didymos by analysing the motion of a particle on its surface. In spite of this rich body of work, a continuum analysis of granular flows in an extraterrestrial environment is uncommon.…”