Chemical and solar electric propulsion options for a cornerstone mission to mercury

In its recent meeting in Naples, ESA has confirmed a mission to Mercury as the conrerstone element of its Horizon 2000+ program for solar system science. The main trade-offs of the mission analysis are presented. 8 missions opportunities with chemical propulsion have been found between 2006 and 2012, with cruise durations of 6 to 7.8 years. The selected option provides much shorter cruise times of 2.1 to 2.6 years. It combines gravity assists with solar electric propulsion (SEP) for the cruise phase and chemical propulsion for insertion and orbital manoeuvers in orbit around Mercury. This strategy which provides the best compromise between the mass budget and the cruise time will be tested at the end of 2002 by the SMART-I mission recently approved by ESA, which combines SEP with lunar gravity assists. (C) 2000 International Astronautical Federation. Published by Elsevier Science Ltd. All rights reserved.