FREQUENT ACCESS TO MERCURY IN THE EARLY 21ST-CENTURY - MULTIPLE MERCURY FLYBY MISSION VIA ELECTRIC PROPULSION

Multiple Mercury swingby sequence is applied to Mercury orbiter concep t to provide sufficient payload mass. On the other hand consecutive fl ybys may become the mission objective itself as was realized by the Me rcury flyby mission U.S.Mariner 10 in 1974 - 1975 which included tripl e consecutive flybys. This paper focuses on this Mariner 10 type flyby mission and investigates the use of an Solar Electric Propulsion (SEP ) in the Mercury-Mercury transfer phase, taking the advantage of the s olar power availability during the interplanetary cruising inside Eart h orbit. The use of SEP upgrades the resultant spacecraft mass as well as increases scientific observation opportunity. As an illustration, a small spacecraft design example is also presented. Copyright (C) 199 7 Elsevier Science Ltd.