Victor Trakhtengerts (1939-2007) was Head of the Sector of Ionospheric and Magnetospheric Physics, at the Institute of Applied Physics, Russian Academy of Science, and Professor of the State University in Nizhny Novgorod, Russian Federation. He was a member of Editorial boards of Geomagnetism and Aeronomy and the Journal of Solar-Terrestrial Physics. Michael Rycroft is a Visiting Professor at the School of Engineering, Cranfield University, U.K., and at the International Space University in Strasbourg, France. He was Editor-in-Chief of the Journal of Atmospheric and Solar-Terrestrial Physics from 1989 to 1999 and, since 2002, has been Managing Editor of the overview journal Surveys in Geophysics.