The past six decades of space exploration have taken their toll on the safety of satellite operations in near-Earth space. A large population of mission-threatening debris has accumulated in key orbital regions, comprising a mixture of abandoned spacecraft, fragments from collisions or explosions, and mission-related objects that no longer serve a purpose. Of particular concern is the situation in low Earth orbit (LEO), where certain bands are expected to be on the cusp of a “Kessler cascade”, whereby collisional fragments seed further collisions, and so on. Large LEO constellations look set to place an even greater strain on space surveillance systems, with several thousand spacecraft licensed to launch over the coming decade. That
said, the problem is by no means limited to the LEO region. Indeed, the population of small debris at geosynchronous (GSO) altitudes remains largely uncharacterised, owing to the limited time available on sufficiently sensitive sensors.

A wide variety of solutions have been posed across different sectors, from the drafting of universal debris mitigation guidelines, to the development of in situ technologies for servicing or removing spacecraft. Meanwhile, it is essential that the
debris environment continues to be probed by surveillance sensors, in order to better inform future avenues for research into the safe and sustainable use of outer space. This thesis explores a number of ways in which optical imaging can contribute to enhanced levels of space situational awareness, using datasets acquired by a selection of instruments at the Roque de los Muchachos Observatory on La Palma.

The 2.54m Isaac Newton Telescope was used to conduct a blind survey of the GSO region, uncovering debris fragments too faint to be reliably tracked and catalogued by the US Space Surveillance Network. Photometric light curves were extracted from the survey frames, and many of the detected objects were found to exhibit signs of rapid tumbling. Simultaneous observations of the survey fields were
acquired using a 36 cm robotic astrograph. A comparative analysis of the resulting datasets was performed to investigate the benefits of pairing a large aperture telescope with a wide-field commercial-off-the-shelf instrument when tasked with surveying the GSO region. In two further surveys, the repurposed SuperWASP-North array and the astrograph were used to carry out targeted observations of catalogued LEO and GSO spacecraft, respectively. Light curves were extracted
from early prototype observations, and orbital arcs from the surveys were used as case studies to test a custom orbit refinement algorithm.