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Last month, scientists unveiled the world"s first wooden satellite, which they say will pave the way for more wood in space. They say the material is more durable and less polluting than metals used in traditional satellites.Researchers from Japan"s Kyoto University and Tokyo-based logging company Sumitomo Forestry unveiled a satellite called LignoSat at the end of May. The cube, about 10 centimeters long, is made of magnolia wood panels and has an aluminum frame, solar panels, circuits and sensors. The panels use Japanese carpentry methods that do not rely on glue or metal studs.Wood may seem reluctant to use in a space because it is flammable, but this property can be desirable.

To curb the growing problem of space debris threatening spacecraft and space stations, rocket stages and satellites are deliberately submerged into the Earth"s atmosphere to burn. However, when they are burned, they emit particles of aluminum and other metals. Many more spacecraft launches are planned, and scientists have warned that the environmental impact of this pollution is unknown.When LignoSat plunges back to Earth after six months or a year of use, the magnolia will burn completely, releasing only water vapor and carbon dioxide, says Kyoto University astronaut and engineer Takao Doi, who is part of the research team.

He points out other advantages of wood: it withstands harsh room conditions and does not block radio waves, which is why it fits into the antenna housing.And there is precedent for spaceships with wooden parts. NASA"s Ranger 3 probe, launched in 1962, had a balsa wood hull that protected the capsule during its descent to the surface of the Moon (the probe failed, passed the Moon and began orbiting the Sun).

Wood Pioneers

LignoSat costs about $191,000 to design, manufacture, launch and operate. On-board sensors measure the tree"s voltage, temperature, geomagnetic forces and cosmic rays, and receive and transmit radio signals. The satellite was handed over to the Japan Aerospace Exploration Agency (JAXA) and will be handed over to the International Space Station in September before launching into orbit in November.The growth of the project has been slow, and it began in 2020 with speculation about the wider potential of wood for better durability in space."During our first discussions, Dr. Doi suggested building a wooden house on the moon," says team member Koji Murata of the Biomaterials Laboratory at Kyoto University"s School of Agriculture. "We also discussed the possibility of building a wooden dome on Mars to grow a forest forest."Mars and lunar colonists, like all pioneers, would have to use local materials - in the case of Mars, regolith (rocky material on the surface), silica and other minerals. But wood can play a role in creating temporary or permanent shelters.

Murata points to plans by JAXA and industrial partners to develop partially wooden shelters that could be used in Antarctica or the Moon."The natural radiation shielding properties of wood can be used effectively in the design of walls or outer shells of space environments," says Nisa Salim, who specializes in engineering materials at Swinburne University of Technology in Melbourne, Australia. and it is not part of the project. "Wood is an effective insulator that can regulate temperature and minimize heat transfer to maintain a comfortable indoor environment.

Wood is easily processed, renewable and biodegradable, which meets the sustainability goals of space exploration."Salim pointed out that the structural integrity, safety and longevity of wood must be confirmed in space.Wood consists of cellulose held together by lignin, a type of organic polymer. That makes it a naturally occurring member of the class of composite materials, says Scott J McCormack, a materials engineer at the University of California, Davis, who is not involved in the project. Composites are often used in the aerospace industry, so he doesn"t think it"s surprising that their use in satellites could be explored."Composites are ideal for the aerospace industry – and also for satellites – because of their high strength-to-weight ratio," says McCormack. But he doubts how wood will fare as a structural material on the Moon or Mars.The most significant issue to consider is the impact of galactic cosmic radiation (GCR) on wood mechanical properties over time. Thanks to the atmosphere, the GCR is not such a big problem for us here on Earth.

According to Murata, the team studied measurements of GCR and solar particles - high-energy particles emitted from the sun - by NASA"s Curiosity rover on Mars, as well as the effects of gamma rays on wood on earth. He believes that a tree on Mars can last thousands of years."Human beings are also affected by the harmful effects of Mars radiation," he remarks."It"s safe to assume that the tree won"t face any significant challenges.".