The objective is to build and test a prototype electron emitter that will use electric field-induced electron emission to reduce the absolute potential of a charged spacecraft.

Spacecraft electrostatic charging in hot plasma environments leads to the risk of damaging electrostatic discharges and is linked to many serious incidents of anomalies and damage to spacecraft electronics. In principle, the charge can be removed by active emitters (guns) but this adds to the system complexity and cost. A GSP study used theory and simulation to explore the possibility of a passive system in which naturally occurring potential differences on the spacecraft can be used to drive an electron emitter, which safely lowers the spacecraft potential. The study showed that such a system should be feasible and produced a conceptual design called SCAPEE. This proposes use of a system of spikes and a mask to create high electric fields. Carbon nano-tubes provide a further enhancement to the fields that are calculated to be sufficiently high to drive the electron field-emission processes. The next goal for the development of this device is to prove it works in the laboratory. For this, the design must be optimised and a prototype manufactured. Testing will be under vacuum and will characterise the current-voltage characteristics of the device.