Wooden satellites

Sustainable wooden satellites

Japanese company Sumitomo Forestry and Kyoto University have joined forces to reduce climate change caused by space junk.

Satellites are increasingly being used for communication, television, navigation and weather forecasting. There are currently nearly 6,000 satellites circling Earth, according to the World Economic Forum (WEF). Research firm Euroconsult estimates that 990 satellites will be launched every year this decade, which means that by 2028, there could be 15,000 satellites in orbit. A number that might even increase more as Amazon plans to send 3236 satellites into orbit to support their global internet network and Space X, which already has over 900 satellites in orbit, also plans to send thousands more.

About 60% of the current satellites are defunct (space junk). This space junk is becoming an increasing problem as more satellites are launched into the atmosphere. Space junk travels at an incredibly fast speed of more than 22,300 mph, so can have cause considerable damage to any object that it might hit. In 2006, a tiny piece of space junk collided with the International Space Station. Luckily it only took a chip out of the heavily reinforced window, but collisions like these are very dangerous to all traffic in space.

Space experts and researchers have been investigating different options to remove and reduce the space junk. One of these options might be a partly wooden satellite. Although broken wooden satellites can also cause serious damage when they collide with space traffic, at least it will be more environmental friendly to dispose of them after use. When current satellites re-enter Earth’s atmosphere their burning creates tiny alumina particles which will float in the upper atmosphere for decades. These particles reflect returning heat radiation from earth back into the atmosphere, causing the temperature on earth to rise.

Takao Doi, a Japanese professor at Kyoto University and former astronaut told the BBC that they are very concerned about the long term effect of all these alumina particles in the atmosphere. As an astronaut he visited the International Space Station in March 2008 and now he works together with Sumitomo Forestry on the development of a partly wooden satellite. Sumitomo Forestry is part of the Sumitomo Group, which was founded more than 400 years ago.

The idea behind the wooden satellite is the belief that wood does not interfere with electromagnetic waves or the Earth’s magnetic field. Thus, if antennae and control mechanisms are put inside a wooden box, it would not only reduce cost but would also allow a simpler structure. However, wood is not the ideal material in space. While it will not rot, it may not withstand the harsh condition of launch. Furthermore, wood contains organic compounds such as water that will evaporate in space, compromising its structural integrity.

The partnership between Kyoto University and Sumitomo Forestry has started research on tree growth and the use of wood materials in space. Next step will include experimenting with different types of wood in extreme environments on Earth. The challenge is to grow and develop wooden materials highly resistant to temperature changes and sunlight. But the team believes it can mitigate the risks. When they succeed their wooden satellites would burn up without releasing harmful substances into the atmosphere or raining debris on the ground when they plunge back to Earth. The first trial is scheduled for 2023.