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Japan team eyeing wooden satellite launch to test how material changes in space

This graphic shows an image of a wooden artificial satellite. (Image courtesy of Kyoto University and Sumitomo Forestry Co.)
A panel containing three different types of wood that will be used in the experiment in outer space is seen. Part of it is covered with a special resin sheet for comparison. (Photo courtesy of Kyoto University associate professor Koji Murata)

KYOTO -- A team of researchers in Japan aiming to launch the world's first wooden satellite that will not pollute the Earth's atmosphere upon reentry are planning to test how the material changes in outer space.

    Researchers from Kyoto University and Tokyo-based Sumitomo Forestry Co. will jointly conduct the experiment, carrying wood samples by supply ship to the International Space Station's external experiment platform as early as December, to analyze the effects of their exposure to cosmic radiation and other environmental factors in outer space for about half a year. They intend to utilize the data to design a wooden artificial satellite they aim to launch in 2023.

    The strength of various materials degrades in space due to radiation. At the space station's orbiting altitude of around 400 kilometers high, atomic oxygen -- generated when the sun's ultraviolet rays decompose oxygen molecules -- is the atmosphere's main element, and it is thought that the surface of the wood will be chipped away as carbon is removed from the material.

    In the experiment, a panel with three kinds of wood samples of varying hardness -- Japanese bigleaf magnolia, mountain cherry tree and gold birch -- will be lined up and, in cooperation with the Japan Aerospace Exploration Agency, left in space using the external experiment platform of the space station's Japanese experiment module "Kibo." The team will retrieve the panel after it is brought back to Earth as early as June 2022, and analyze how much the samples have degraded and the detailed mechanism of degradation, in the hopes of utilizing the results in the development of highly functional wood.

    The wooden satellite that Kyoto University and Sumitomo Forestry plan to develop will completely burn out upon reentry into the Earth's atmosphere after use, so one of the satellite's potential benefits is that it will not produce "alumina particles" which can cause air pollution. Also, as electromagnetic waves and the Earth's magnetism can pass through wood, an antenna and an attitude control system can be contained inside the wooden satellite, simplifying the structure.

    Team member Koji Murata, an associate professor of wood engineering at Kyoto University, has high expectations for the project. "People tend to think that wood, a material familiar to us, is unconnected with outer space, but there is a high possibility that they are usable materials. We'd like to obtain beneficial data so that wood can travel with humans to outer space," he said.

    (Japanese original by Norikazu Chiba, Kyoto Bureau)

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