Outer solar system exploration by a small spacecraft using a solar power sail is investigated. A solar power sail is an extended form of a solar sail that has thin-film solar cells attached over its surface. This concept makes it possible to generate a large amount of power with less weight resources than conventional means. Thereby, even a small spacecraft, which has a strong constraint on available resources, can drive high-power ion thrusters to obtain large $\Delta V$. Combining electric propulsion with gravity assists allows the spacecraft to reach the outer solar system using less propellant. The spacecraft can not only survive by means of solar power in the outer solar system, but also drive electric thrusters there to perform challenging missions such as asteroid or comet rendezvous. In this paper, a framework for exploring the outer solar system using a 50-kg-class small spacecraft is presented. The characteristics of solar electric propulsion under the solar power sail model are disclosed, and a design scheme for missions to the outer planets and beyond are addressed. Providing the specific design of the 50-kg-class solar power sail-craft, Centaur rendezvous mission design is performed as a feasibility study.

研究了小型航天器利用太阳能帆对外部太阳系的探索。太阳能帆是太阳能帆的一种扩展形式，其表面附着有薄膜太阳能电池。与常规装置相比，该概念使得可以用较少的重量资源来产生大量的功率。因此，即使是对可用资源有严格限制的小型航天器，也可以驱动大功率离子推进器来获得大型$\Delta V$。将电力推进与重力辅助相结合，可使航天器使用较少的推进剂到达外部太阳系。航天器不仅可以依靠外部太阳系中的太阳能生存，而且可以驱动那里的电动推进器执行具有挑战性的任务，例如小行星或彗星会合。在本文中，提出了使用50公斤级小型航天器探索外部太阳系的框架。公开了在太阳能帆模型下的太阳能推进的特性，并提出了向外行星飞行任务的设计方案。通过提供50公斤级太阳能帆艇的特定设计，执行Centaur交会任务设计是一项可行性研究。