Update on Ryugu spectral surface regions classification: dimensionality reduction, manifold learning and unsupervised clustering of NIRS3 data

The Haybusa-2 spacecraft approached the C-type Near Earth asteroid 162173 Ryugu on June 2018. Haybusa2 is equipped with three remote sensing instruments such i.e. as the Thermal Infrared Imager TIR, the NIRS 3 spectrometer [3] and the Optical Navigation Camera-Telescopic (ONC-T) with a wideband and seven narrow band filters.Ryugu is a top-shaped Cb type asteroid and is covered by a large number of boulders. It is one of the darkest object in our Solar System with a quite homogenous composition, including OH-rich materials