Abstract :
The last few years have seen an exponential growth in the number of orbiting satellites and space debris, because of the build-up of mega-constellations of communication satellites, because of tests of anti-satellite weapon systems, and because of accidental collisions and break-ups. This rapid growth will continue over the coming decades, with forecasts for hundreds of thousands of large objects in orbit in the coming decade. This raises urgent sustainability concerns from several different perspectives. For astronomy, one of those concerns is that the huge number of satellites (with loud radio emissions and bright optical reflection) form an increasingly important source of human-made noise in our data.
This growth of the number of space objects has greatly increased the importance (and financial value!) of accurate monitoring of orbiting objects (e.g. position, velocity, attitude), not just in low-Earth orbit but also in the much higher geostationary orbits,
where the largest and most expensive satellites are located. Astronomers like us have some fantastic tools for this, and in this talk I will show some work on using optical polarimeters to study the reflection behaviour of both active (i.e. attitude controlled)
satellites, and the (spin) dynamics of dead satellites and debris in graveyard orbits. I will also highlight some ways in which
orbiting debris can be used as a tool, to study astronomically relevant physics.
