Sazhen-S () is a Soviet laser/optical space surveillance system, used to analyse the orbital parameters of space craft. There are several installations across the former Soviet Union. One of which is based at space ground station NIP-19 near Dunaivtsi in Ukraine. It is named after the sazhen, a former Russian unit of measurement which translates as fathom and has a length of . A similar system is Sazhen-T.