Venus express: Highlights of the nominal mission by Titov, D, Svedhem, H, Taylor, F, Barabash, S, Bertaux, J, Drossart, P, Formisano, V, Haeusler, B, Korablev, O, Markiewicz, W, Nevejans, D, Paetzold, M, Piccioni, G, Sauvaud, J, Zhang, T, Witasse, O, Gerard, J, Fedorov, A, Sanchez-Lavega, A, Helbert, J, Hoofs, R