In May 2023, researchers at Kyoto University and the Japanese-based wood manufacturing company Sumitomo Forestry unveiled the world’s first wooden satellite, breaking new ground in space technology.
Called the LignoSat, this small cube (around 10 centimeters, or 3 inches) contains solar panels and circuit boards built into its wooden sides. These panels contain special fittings that don’t require adhesive but allow the sides to interlock into place using traditional Japanese wood-carving techniques.
The project began slowly in 2020. Since its unveiling, the satellite has been transferred from its research facility to JAXA (Japan Aerospace Exploration Agency), where it will undergo further durability testing before being transferred to the ISS in September 2024. LignoSat will then be launched into orbit in November.
Surprisingly, wood has proven to be an eco-friendly choice for space instruments. Its easy combustibility makes it a more environmentally friendly alternative to metal satellites, offering a promising step towards sustainable space exploration.
“Wood is an effective insulator, capable of regulating temperature and minimizing heat transfer to maintain a comfortable indoor environment. Wood is easy to work with, renewable and biodegradable, aligning with sustainability goals for space exploration,” stated Nisa Salim, a researcher at Swinburne University of Technology in Melbourne, Australia, who is not part of the project, in a recent Nature article on this announcement.
An Eco-Friendly Re-entry and Other Benefits
While metal satellites can be built to withstand the heat of Earth’s atmosphere from both launching and re-entry, these instruments emit metal particles of aluminum, titanium, and other pollutants that can find their way into the atmosphere, waterways, and other places. While these emissions haven’t yet been thoroughly studied, scientists are already warning that more launches of metal satellites could have bigger pollution implications than expected.
Wooden satellites, however, immediately combust upon re-entry, becoming a small cloud of carbon dioxide and water vapor as the wood panels incinerate and burn, leaving no potentially harmful particulates behind.
Other benefits of wooden satellites include their permeability to radio waves, which allows them to transmit and communicate like other satellites. Wood’s durability makes it seem like it would withstand harsh space environments, especially crushed wood, which is stronger than steel.
Whether wooden spacecraft can withstand cosmic radiation, where waves of high-energy particles bombard the Earth and its surrounding satellites, has yet to be tested. Presently, some experts believe that exposure to cosmic radiation may degrade the wood faster than expected.
Lack of Samples
Wooden satellites have other potential drawbacks, including lack of recovery. Because of wood’s high flammability, any wooden satellite launched into orbit could not be launched using the traditional method, and upon re-entry, nothing from the instrument could be recovered. This limitation forces space agencies to produce entirely new satellites without being able to recycle parts, which can add to the cost of the overall device.
Additionally, any extra recorders, sensors, or other measurement devices attached to the satellite would be lost, along with their data.
A Low-Cost Alternative
There is also the concern of cost, which thankfully doesn’t really affect the LignoSat.
Most satellites cost tens to hundreds of millions of dollars, with the launch being the most expensive component. While some sites quote anywhere from $10 to $400 million, NASA calculated a maximum of $260 million for a hypothetical case.
According to the Nature article on this announcement, the LignoSat costs around $191,000 to design, create, launch, and maintain, a fraction of the average satellite’s costs. The lower cost is partly due to its launch limitations, where it must be bundled with other missions to be launched without incinerating, saving space agencies money. Wood is also a much cheaper material than metals used in other satellites, making the instrument a much more cost-effective option.
The Future of Space Shelters?
Inspired by the many benefits and low cost of their wooden satellite, Kyoto University and Sumitomo Forestry researchers have also begun investigating using wood as the base material for future space shelters.
“In our first conversations, Dr Doi proposed we build wooden housing on the Moon,” stated researcher Koji Murata at the biomaterials-design laboratory at Kyoto University’s Graduate School of Agriculture in the Nature article. “We have also discussed the possibility of building domes on Mars out of wood in order to grow timber forests.”
When considering the costs of colonizing the Moon or Mars, the benefits of using wood to construct temporary or permanent shelters cannot be ignored. Murata plans to explore this further by collaborating with JAXA and other industry partners to create partial wooden shelters to be tested in Antarctica and on the Moon.
Should these shelters prove successful, future advancements in space exploration may use something much closer to home to take us farther away from Earth.
Kenna Hughes-Castleberry is the Science Communicator at JILA (a world-leading physics research institute) and a science writer at The Debrief. Follow and connect with her on X or contact her via email at kenna@thedebrief.org