Asteroid binary formation is a hot topic in planetary science. A population of binary asteroids is known to be part of the Near-Earth Asteroid (NEA) population (at least 15%). For some of those systems radar observations are available and a few shape models have been produced out of observations. While dynamical transition from components resting on each other to binary system has been studied by Jacobson & Scheeres (2011), the problem of asteroid binary formation 'per se', has been only partly studied in the past and no global approach to the problem has been tried so far. Walsh et al. (2008, 2012), Sanchez & Scheeres (2011, 2012) and Campo Bagatin et al. (2020) found different formation scenarios ranging from equatorial mass shedding to fission to binary formation in the process of post-impact mass re-accretion. Former approaches used mono- and limited multi-disperse spherical mass distributions and did not study in detail the dependence of outcome on nucleus stiffness/rigidity. We propose a novel thorough ‘end-to-end’ approach, in which the parent body is simulated as an ensemble of irregular shape components with arbitrary mass distribution. Slow spin-up reproducing YORP effect is followed to -and beyond- the critical rate so that the outcome –including shape of the primary- can be linked to internal stiffness (related in turn to mass distribution, shear strength and cohesion). This study will also investigate the conditions under which asteroid pairs and clans are formed, analyzing if they can be interpreted as part of the same spin-up evolution mechanism. The outcome of this study will be compared to the conclusions on the formation of the binary NEA Didymos, which physical characteristics will be measured by the Hera (ESA) mission. The conclusions of our ‘end-to-end’ study may also be helpful in the interpretation of other interesting phenomena like the formation of the recently discovered rings around some Centaurs (and potentially other small bodies).
