A comet nucleus sample return mission using solar electric earth gravity assist

The paper presents the Comet Nucleus Sample and Return (CNSR) Mission strategy using electric propulsion. The mission objective is very clear and may provide clues to the understanding of the origin of the solar system and of life. The target comet here is an extinct comet, to which a concrete and promising sample collection scenario was constructed. The essence of this paper lies in the use of its novel energy accumulation ring located around the Earth trajectory that gains the angular momentum that results in the high speed Earth swing-by after one or one and a half year quasi-synchronous flight. The spacecraft returns back to the Earth at a specific period regardless of how large the relative excess velocity is gained. This is the essence of the scheme. While the targets accessed via the scheme shown are limited, this strategy enables even a NASA DISCOVERY class, small spacecraft to perform the valuable CNSR mission. The plan is found feasible, and the launch window is open in 2005 and the spacecraft can return the sample back to the Earth in only eight years. Another window in 2009-2010 is also provided. A concrete proposal is shown for the comet Wilson-Harrington (W.H.) here. The ISAS of Japan opens the window to the international organizations for collaboration in this mission.