When the European Space Agency (ESA) designed a spacecraft to fly closer to the sun than anyone else in history, it had a big problem: how to protect the probe from extreme heat and radiation. The Solar Orbiter was launched in February 2020 and recently made its first pass near the sun. It must be able to withstand temperatures hot enough to melt lead, as well as 13 times the radiation that reaches the Earth's surface.
Initially, the agency was looking for conventional solutions, based on metals and carbon fiber, but they were not good enough, said Cesar Garcia Marirrodriga, ESA project director for Solar Orbiter, at CNN Business. Instead, the agency found the answer in a material dating back to the Stone Age.
After ESA submitted a call for solutions, it was approached by the Irish biotechnology company ENBIO. He had developed a technique for the application of synthetic bone coatings to orthopedic and dental implants, so that they are more easily accepted by a patient's body. Because the technique reduced weight and prevented issues such as peeling, ENBIO considered it to be useful for Solar Orbiter titanium surfaces.
But the synthetic bone was light in color and tests showed it would darken after prolonged exposure to Sun light, changing the amount of heat that can be absorbed and reflected. A black coating would mean that its properties would be stable for the entire shipment.
Instead, the company started looking for a natural black powder. "I remembered reading as a child that in cave murals, people used charcoal and, in some cases, [burnt] animal bones to paint the walls," said John O'Donoghue, founder of ENBIO.
After O'Donoghue supplied ESA with burnt animal bone powder, she found it to be ideal for solar missions. "Apart from being black, there is no fuel in the material - so when heated it does not release gases that could damage the spacecraft," explained Garcia Marirrodriga.
The resulting coating, called SolarBlack, covers about one-fifth of the surface of the Solar Orbiter and retains its most sensitive parts at room temperature while absorbing heat (up to 1.000 degrees Fahrenheit). ENBIO, in collaboration with Airbus (EADSF), also developed SolarWhite, a white coating that covers other parts of the satellite where sunlight should be reflected rather than absorbed.
Source of information: edition.cnn.com