Recently, the world’s first radioactive20Na beams have been accelerated at the TRIUMF facility. Using the TRIUMF‐UK Detector Array facility we have performed elastic scattering of this beam from protons in a CH2target with the aim of determining resonance parameters of states in21Mg. The region of excitation probed in21Mg has astrophysical importance because resonant contributions to the20Na(p,&ggr;)21Mg reaction rate are thought to be part of the breakout path from the hot CNO cycle to the rp‐process in x‐ray bursters and perhaps novae. The data taken also serve a wider purpose in that comparisons may be made to isobaric analogue states in the mirror21F nucleus, and thus a study of Coulomb energy shifts may be undertaken. An overview of the motivation, of the experiment, and a preliminary analysis of the data taken, is presented. © 2003 American Institute of Physics