There was a flurry of stories recently about a Japanese plan to create satellites made out of wood. Apparently, the intent is to reduce the amount of debris created when a satellite re-enters the earth’s atmosphere. The BBC captured the typical reporting on the idea thusly,
Space junk is becoming an increasing problem as more satellites are launched into the atmosphere.
Wooden satellites would burn up without releasing harmful substances into the atmosphere or raining debris on the ground when they plunge back to Earth.
“We are very concerned with the fact that all the satellites which re-enter the Earth’s atmosphere burn and create tiny alumina particles which will float in the upper atmosphere for many years,” Takao Doi, a professor at Kyoto University and Japanese astronaut, told the BBC.
“Eventually it will affect the environment of the Earth.”
ArsTechnica, responding to coverage by the BBC and others, noted that while wood might have some potential benefits as a material to make satellites out of, reducing space junk is not really one of them.
Most of the coverage seems to present wooden satellites as helping with the space junk problem because of the fact that wood would burn up when it de-orbits. But this stuff is space junk precisely because it doesn’t de-orbit. All of our plans for handling the existing abundance of space junk involve finding a way to induce it to leave orbit. Wood won’t make any difference here.
The one point that wood might have in its favor, noted in some of the coverage and by Doi himself, is that it won’t leave much in the atmosphere if it does de-orbit and burn up. Most other hardware will vaporize into a gas of aluminum and various other metals, perhaps oxidized. Again, having a wood housing won’t eliminate these metals, given that many of them come from the satellites components and the rocket that put them in place. And, at least for the foreseeable future, this material won’t be present in the atmosphere at high enough levels to be meaningful.
Given all this, it’s completely unclear what problem wooden satellites are meant to solve. Still, the idea of figuring out how to process wood so that it would function in this context is an intriguing materials science problem, and might have some very down-to-earth applications. So, here’s to hoping that the project goes ahead regardless.