Japanese scientists have created one of the world’s most unusual spacecraft – a tiny satellite made of wood.
The LignoSat probe is constructed of magnolia wood, which in experiments carried out on the International Space Station (ISS) was found to be particularly stable and crack-resistant. Now plans are being finalized for it to be launched on a US rocket this summer.
The wooden satellite was built by researchers at Kyoto University and logging company Sumitomo Forestry to test the idea of using biodegradable materials such as wood to see if they could act as environmentally friendly alternatives to the metals from which all satellites are currently built. .
“All the satellites that re-enter the Earth’s atmosphere burn up and create small alumina particles that will float in the upper atmosphere for many years,” Takao Doi, a Japanese astronaut and aeronautical engineer at Kyoto University, recently warned. “Eventually it will affect the environment of the Earth.”
To tackle the problem, Kyoto researchers set up a project to evaluate wood species to determine how well they could withstand the rigors of space launch and long flights in Earth orbit. The first tests were carried out in laboratories that recreated conditions in space, and wooden samples were found to have no measurable changes in mass or signs of decomposition or damage.
“Wood’s ability to withstand these conditions amazed us,” said Koji Murata, head of the project.
After these tests, samples were sent to the ISS, where they were subjected to exposure tests for almost a year before being brought back to Earth. Again, they showed little sign of damage, a phenomenon Murata attributed to the fact that there is no oxygen in space to burn wood, and no living things to rot it.
Various types of wood were tested, including Japanese cherry, with wood from magnolia trees being the most robust. It has now been used to build Kyoto’s wooden satellite, which will house a number of experiments that will determine how well the spacecraft performs in orbit, Murata said.
“One of the missions of the satellite is to measure the deformation of the wooden structure in space. Wood is durable and stable in one direction, but can be prone to dimensional changes and cracking in the other direction,” he told the Observer.
Murata added that a final decision has yet to be made on the launch vehicle, with choices now limited to a flight this summer on an Orbital Sciences Cygnus resupply ship to the ISS or a similar SpaceX Dragon mission slightly later in the year. The probe – which is the size of a coffee mug – is expected to operate in space for at least six months before being allowed to enter the upper atmosphere.
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If the LignoSat performs well during its work in orbit, the door could be opened to the use of wood as a construction material for more satellites. It is estimated that more than 2,000 spacecraft are likely to be launched annually in the coming years, and the aluminum they are likely to deposit in the upper atmosphere as they burn up on re-entry could soon cause major environmental problems.
Recent research conducted by scientists at the University of British Columbia, Canada has revealed that aluminum from re-entry satellites can cause serious depletion of the ozone layer that protects the Earth from the sun’s ultraviolet radiation and also the amount of sunlight which can move through the atmosphere and reach the ground.
However, this should not be a problem with satellites built of wood, such as LignoSat, which, when it burns up on re-entry into the atmosphere after completing its mission, will only produce a fine spray of biodegradable ash.
