Electric propulsion systems for small satellites: the low earth orbit mission perseus D. Bock, G. Herdrich, M. Lau, M. Lengowski, T. Schönherr, F. Steinmetz, B. Wollenhaupt, O. Zeile and H.-P. Röser Published online: 01 October 2012 DOI: 10.1051/eucass/201102629