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.

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Japan Aerospace Exploration Agency (JAXA) successfully achieved the world’s first solar power sail technology by IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) mission in 2010. It demonstrated a photon propulsion and power generation with thin-film solar cells during its interplanetary cruise. A sail of 200 m² was deployed and kept extended using centrifugal force of the spacecraft rotation. IKAROS also succeeded in accelerating and controlling the orbit by actively exploiting solar radiation pressure, and thus became the world’s first operational solar sail spacecraft flying an interplanetary voyage. This paper presents the mission and system design of IKAROS and its operation results.

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IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) developed by JAXA is the world’s first operational solar sail spacecraft, and was launched in May 2010. This paper presents the development of a solar sail membrane of IKAROS introducing overall design considerations and each element such as a thermoplastic polyimide membrane, thin-film solar cells and reflectivity control devices. This paper also shows the evaluation of the spacecraft on orbit using flight data.

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Japan Aerospace Exploration Agency (JAXA) launched the solar power sail orbiter ‘Interplanetary Kite-craft Accelerated by Radiation Of the Sun: IKAROS’, on May 21st, 2010. IKAROS was launched by H-IIA 17th vehicle dual-launched with ‘Venus Climate Orbiter: AKATSUKI’. IKAROS demonstrates a new propulsion technology of utilizing photons from the sun for deep space exploration, which is called the Solar Power Sail technology. In a case of the solar system exploration, an ion-propulsion engine is effective as a main propulsion system because it has high specific impulse and it can provide a continuous acceleration. However, the ion-engine needs high electric power in proportion to its performance. The solar power sail technology we developed can be a hybrid engine, which can provide high electric power generated by very thin flexible solar arrays attached on the solar sail, while obtaining acceleration generated on the solar sail by the sun radiation. IKAROS succeeded in deploying the solar power sail in an interplanetary orbit, on June 9th, 2010 for the first time in the world, and we obtained various flight data of the solar power sail deployment mission. We report the details of the on-orbit result of IKAROS’s solar power sail deployment mission and the result of numerical simulation compared with the flight data.

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This paper summarizes the attitude determination and control operation of IKAROS. IKAROS achieved the world’s first interplantery solar sailing in 2010, in which the attitude determination and control system (ADCS) worked as an essential element of the spacecraft operation. IKAROS is a spinner spacecraft equipped with a very large and flexible sail expanded by centrifugal force. IKAROS is also a low cost and piggy-back mission. Hence unique set of attitude determination system and actuators are adopted, which successfully provide the sufficient performance under limited resource. This paper introduces key technologies and achievements of the IKAROS ADCS covering sun-Earth based attitude determination, Gas-liquid phase equilibrium reaction control system, Reflectance control devices. The ADCS-related operation results such as sail deployment and cruising phase operation are also summarized.

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This paper summarizes the guidance, navigation and control of the world’s first solar power sail IKAROS. During the 1.5 years of its interplanetary flight, IKAROS has carried out the guidance, navigation and control experiments using the large solar radiation force generated by its 200 m2 solar sail. Since solar radiation pressure is the main controllable force for a solar sail, its modeling is the key factor for a successful guidance. A precise solar radiation pressure modeling for this spinning solar sail has been performed in order to support the navigation and guidance using the large membrane. Due to the complexity of the sail surface and shape, the refinement of the SRP model is done after the deployment in space with radiometric measurements. This solar sail navigation is also supported by the precise delta-DOR (Differential One-way Range) measurements. These in-flight demonstrations with IKAROS enable the future deep space exploration with solar sailing technique.

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