Building a Satellite out of Wood? Use Magnolia

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It doesn't really make sense at first glance to imagine wooden satellites. We have grown up watching movies and real life videos of metallic spacecraft and manmade objects in orbit around Earth or sent into space for exploration. Wood? Isn't that a major step backwards in technology?

Wood paneled satellite image (from asia.nikkei.com)

Here are some reasons to consider wood. 

• It's cheaper than the current material, aluminum.
• It's a sustainable material.
• It's strong, flexible, and lightweight.
• It burns up better on re-entry than metal.
• It allows electromagnetic waves to pass through, so antennas can stay inside.

The United States actually used balsa wood for the Ranger 4 lunar explorer in 1962. The top spherical section filled with liquid contained a seismometer and was supposed to separate before the hard landing. The rest of Ranger 4 would land and take other measurements. But a malfunction caused Ranger 4 to crash without sending back any data.

Ranger 4 and its impact limiter top  (photos from universetoday.com)

In 2017, work in Japan began to test various woods under vacuum conditions on Earth. Kyoto University (Japan) looked at cedar, cypress, satinwood, magnolia, and zelkova after 6 months in a vacuum. No deterioration was seen in any samples, and the elastic properties for three seemed unaffected compared to the others.

Professor Koji Murata, member of Kyoto University's Biomaterials Design Lab, joined forces with Sumitomo Forestry and Japan's space agency JAXA with a plan in 2021 to send some wooden samples to the experiment platform of the Kibo module on the International Space Station (ISS). In March 2022, that plan was executed. 

They sent up 3 types of ordinary furniture wood to the ISS and exposed them to space to see how their quality deteriorated with temperature changes and cosmic radiation. The result? No warping, no cracks, no peeling, no other obvious problems.

The Kibo module and wood samples

You might wonder about other space junk that has fallen back to Earth. Doesn't it completely burn up except for the larger denser parts that land? Actually, no. As things begin to burn up, they loosen and fall apart. Tiny fragments may spray back into orbit again. They are nearly impossible to track, and since they are traveling at 28,000 km/hr (17,000 miles/hr), even a small metal part can cause a lot of damage if it hits another satellite or a manned craft. See the window crack below.

Window damage on the ISS (NASA)

If a satellite housing is composed of wood, radio waves can pass through without interference. The WoodSat or LignoSat could therefore be made more compact for launch, and it wouldn't need to open up and allow for a radio antenna to unfold. Recently, the European Space Agency's Jupiter Icy Moons Explorer (JUICE) had this sort of problem with its Radar for Icy Moons Exploration (RIME) antenna and wasted more than three weeks to fix it by jostling the craft remotely. 

Here is a short video explaining the Japanese wooden satellite proposal.

Here is another informative video about wood in space from a DIY woodworking YouTuber!

Finally, a very understandable engineering analysis (video) of using wood for space products.