‘Japanese Magnolia’ floating in space

An ultra-small ‘Lignosat’ made of wood
The space station will be launched into orbit a month later.
6-month durability test in real environments

Existing metallic satellite fuselage
Release of ‘aluminium oxide’ into the atmosphere
Falling temperatures, ozone layer attack potential
“Trees to Ashes… “Low Environmental Impact”

US Public Interest Research Agency Space Scientists
Concerns about ‘generic satellites’ such as Starlink
“Launch suspended pending environmental impact review”

A cube so small you can fit it in the palm of your hand sits on the desk. It is only the size of a desk clock. However, there is no hour or minute hand. It’s hard to guess his reason just by looking at his appearance. When you examine the surface of an object, you see a soft wave pattern. It means it is made of wood.

This object is ‘Lignosat’, an artificial satellite developed by Japan. Humanity has been launching artificial satellites since the 1950s, and the fuselage material was all metal. Wooden satellites appeared, breaking the conventional wisdom that had existed for over fifty years.

Why did they use wood instead of the metal that was used so well? This is because an unexpected problem was discovered with a metallic satellite.

‘Lignosat’ tested in Earth orbit

According to the National Aeronautics and Space Administration (NASA) and Reuters, Lignosat, developed by researchers at Japan’s Kyoto University in collaboration with Sumimoto Forestry, was loaded onto an unmanned spacecraft and arrived e the International Space Station (ISS), orbiting 400 km above it. the surface of the Earth, last week. The lignosat is 10 cm wide, 10 cm long, and 10 cm high. As the recent trend of car-sized satellites is common, it is very small. It is a so-called micro-satellite.

But Lignosat’s real feature is not its size. It is fuselage material. Lignosat is the world’s first wooden satellite. The type of wood is ‘Japanese Magnolia’. Japanese magnolia is light and strong. It is mainly used to make furniture and woodwork.

Kyoto University researchers will release Lignosat from the ISS a month later and insert it into Earth orbit. Lignosat is expected to orbit the Earth as a conventional satellite. In Earth’s orbit, the temperature is 100 degrees Celsius in places where sunlight shines, and -100 degrees Celsius in places where it does not shine. Durability tests are carried out for 6 months in this extreme environment.

Kyoto University researchers cut Japanese magnolias into square sticks and passed a stability test carried out in Earth orbit for 10 months in 2022. The researchers plan to see if distortion or cracking occurs even after it is made into a finished product in the shape of a satellite.

Concerns over existing satellites ‘causing a drop in temperature’

But why was a wooden satellite created? There are no particular problems with existing satellites with metal fuselages. There is a reason. This is due to the impact that aluminium, the metal used in satellite fuselages, has on the global environment.

When satellites run out of fuel and cannot move on their own, they fall to earth due to Earth’s gravity, usually several years later. During this process, the satellite body rubs against the atmosphere and becomes a fireball. High heat changes aluminium, the main component of the metal that makes up the fuselage, to ‘aluminium oxide’.

Pieces of aluminum oxide scattered above the Earth reflect sunlight like a mirror. Global temperatures could drop significantly. Aluminum oxide also attacks the ozone layer, which protects against ultraviolet rays in the stratosphere. As more harmful ultraviolet rays fall on the earth than before, there is a great chance that living things will be harmed.

Wood is different. In an interview with Reuters, researchers said, “When trees burn due to contact with the atmosphere, they turn to ash and disappear,” adding, “The effect on the small environment.”

There is also a demand to “stop burning metal objects”

In fact, the problems caused by metallic satellites are widely observed not only by researchers at Kyoto University but also by scientists in other countries. At the end of last month, around 100 space scientists belonging to the US non-profit organization ‘Public Interest Research Group (PIRG)’ sent a letter to the Federal Communications Commission (FCC), which is in charge of licensing launched a satellite in the US. a country

Those affiliated with Harvard University, Columbia University, and Princeton University argued that “the FCC should review the environmental impact of ‘large-scale satellite constellations'” and “that launch has been temporarily suspended until the investigation is completed. ” The satellite constellation that PIRG refers to refers to a group of satellites orbiting the Earth to provide Internet access services anywhere in the world. SpaceX’s ‘Starlink’ is a representative example.

SpaceX has launched up to 6,000 Starlink-powered satellites over the past five years. This is 75% of the artificial satellites (8,000 here) currently orbiting the Earth. The number of satellites for Starlink will increase to around 12,000 by 2027. Starlink satellites also have a metal fuselage, and when they enter the atmosphere, they become aluminum oxide. Since there are so many satellites for Starlink, there is a high possibility that they will cause visible problems in temperature and ozone layer. That’s why PIRG scientists spoke together.

Kyoto University researchers said, “It is possible that satellite fuselages made of metal will be banned in the future.” The research team plans to use durability evaluation data from wooden satellites to investigate whether it is possible to use wood as a building material for future construction in space.