Contact Binary Conundrum: How do small bodies form in the solar system?

I am using optical photometry and archival radar observations to create comprehensive shape and spin-state modelling of several near-Earth contact binary asteroids using both convex inversion techniques as well as radar shape modelling with the SHAPE software. I will also help contribute to the development of the SAGE modelling software to be used as an alternative to SHAPE.

Contact binaries are found throughout the solar system, with notable examples including Itokawa (NEA), Arrokoth (TNO) and the recently discovered Selam (MBA) by the LUCY mission. The majority of comet nuclei also appear to be contact binaries (see 67P, target of the Rosetta mission). Despite over 1000 contact binary candidates having been observed with radar observations from Arecibo and Goldstone currently there are only 13 modelled contact binary asteroids, and I aim to increase this number by 3-4 over the course of my PhD in order to gain insight into their possible formation mechanisms from their shape, bulk properties such as density, and spin-state. Properties like this can allow us to start to view these objects as a population with trends, rather than as unique objects, comparing things like asteroid colour and bulk densities with their shape, in order to make assumptions on which theories formation pathway the object followed.