  Space debris is a major threat to the satellite infrastructure. A collision
with even small particle, e.g. 1 cm of size, can cause a catastrophic event
when the parent body, spacecraft or upper stage, will break up into hundreds of
trackable fragments. Space debris research helps to discover, monitor and
characterize these objects, identify their origin and support their active
removal. Surveys with optical telescopes aim to discover new objects for
cataloguing and to increase the accuracy of space debris population models. The
follow-up observations are performed to improve their orbits or to investigate
their physical characteristics. We will present the space debris population,
its orbital and physical characteristics and we will discuss the role which the
optical telescopes play in space debris research. We will also discuss the
adopted astronomical techniques like astrometry, photometry and spectroscopy
used in the space debris domain.
