  The Murchison Widefield Array (MWA) is a new low frequency interferomeric
radio telescope. The MWA is the low frequency precursor to the Square Kilometre
Array (SKA) and is the first of three SKA precursors to be operational,
supporting a varied science mission ranging from the attempted detection of the
Epoch of Reionisation to the monitoring of solar flares and space weather. We
explore the possibility that the MWA can be used for the purposes of Space
Situational Awareness (SSA). In particular we propose that the MWA can be used
as an element of a passive radar facility operating in the frequency range 87.5
- 108 MHz (the commercial FM broadcast band). In this scenario the MWA can be
considered the receiving element in a bi-static radar configuration, with FM
broadcast stations serving as non-cooperative transmitters. The FM broadcasts
propagate into space, are reflected off debris in Earth orbit, and are received
at the MWA. The imaging capabilities of the MWA can be used to simultaneously
detect multiple pieces of space debris, image their positions on the sky as a
function of time, and provide tracking data that can be used to determine
orbital parameters. Such a capability would be a valuable addition to
Australian and global SSA assets, in terms of southern and eastern hemispheric
coverage. We provide a feasibility assessment of this proposal, based on simple
calculations and electromagnetic simulations that shows the detection of
sub-metre size debris should be possible (debris radius of >0.5 m to ~1000 km
altitude). We also present a proof-of-concept set of observations that
demonstrate the feasibility of the proposal, based on the detection and
tracking of the International Space Station via reflected FM broadcast signals
originating in south-west Western Australia. These observations broadly
validate our calculations and simulations.
