Space applications of micro fabricated field emitters

In this paper, four space based uses of field emitters are described; two of them are field emitting electron sources and two emit ions. Of the electron emitters one is inside the Ptolemy mass spectrometer which was launched in March 2004 on the Rosetta satellite and for the past year has been travelling on its way to a comet Churymov-Gerasimenko in the outer solar system; and the other is still in preparation to provide charge balance for the LISA system of satellites that will measure gravitational waves from colliding black holes and the first instant of the big bang. The two field emitting ion sources are similar types of microthruster used to provide an exceptionally gravitationally quiet environment in order to carry out high precision physics experiments which can only be carried out in space, free from the effects of gravitational noise present in terrestrial laboratories. These examples are selected to illustrate the overhead involved in developing robust, advanced technologies such as field emitter arrays for use in space instrumentation in which fault tolerance and system redundancy must be built in, as recovery and repair is never an option.