In this work the asymptotic solutions of massless spin-3/2 fields are
studied. First, in a Minkowski space, the fields, their potentials, an
d the associated gauges are analysed in the Rarita-Schwinger descripti
on. We exhibit the explicit appearance of the conserved charges of the
fields and their singular behaviour in the potentials. The charges of
the spin-3/2 fields emerge as a global definition of twisters. The ha
t space case serves as a guide in the analysis of the problem in gener
al vacuum spacetimes. Although the fundamental connection between and
the meaning of twisters and charges have not, as yet, been established
in general vacuum spacetimes, some useful insights have nevertheless
been gained in studying the potential-modulo-gauge description of the
spin-3/2 problem in such spacetimes.