Conceptual Study on a Jovian Trojan Asteroid Sample Return Mission

摘要

A solar power sail is a deep space probe to be powered by hybrid propulsion of solar photon acceleration and ion engines to explore the outer planetary regions of the solar system without relying on nuclear technology. The Japan Aerospace Exploration Agency (JAXA) successfully launched and operated the world's first solar sail demonstration spacecraft, "IKAROS" (Interplanetary Kite-craft Accelerated by Radiation Of the Sun), in 2010, and JAXA is currently planning an outer solar system exploration mission using the demonstrated solar power sail technology. The mission will fly to Jupiter, where the spacecraft will drop a tiny Jovian probe and perform a swing-by for a Trojan asteroid. This paper conducted conceptual study for this mission. First, we derived feasible combinations of spacecraft system design parameters such as the weight of the bus, the power generation capability of the solar power sail, and the Isp of the ion engine system, considering the requirement from trajectory analysis. The result suggested that a sail of approximately 50 m wide should be deployed for this mission. Next, in order to extend the output of this mission, the feasibility of an optional sample return mission by a small solar power sail probe was studied. We derived feasible sample retrieval and Earth return scenario and corresponding requirements for the probe configuration, and investigated the system feasibility considering the sample retrieval sequence and Earth return trajectory analysis result. It was found that considerable weight reduction is needed to realize this small solar power sail probe within the 200 kg weight constraints.