  To enable space-based quantum key distribution proposals the Centre for
Quantum Technologies is developing a source of entangled photons ruggedized to
survive deployment in space and greatly miniaturised so that it conforms to the
strict form factor and power requirements of a 1U CubeSat. The Small Photon
Entangling Quantum System is an integrated instrument where the pump, photon
pair source and detectors are combined within a single optical tray and
electronics package that is no larger than 10 cm x 10 cm x 3 cm. This footprint
enables the instrument to be placed onboard nanosatellites or the CubeLab
structure aboard the International Space Station. We will discuss the
challenges and future prospects of CubeSat-based missions.
