Launching a machine toward the sun and getting it in close without damage or disruption of data collection requires advanced technology. But conventional aerospace technology fell a little short in developing the ESA-NASA Solar Orbiter. The space agencies turned to prehistoric technology—cave paint.
All the complex devices and synthetic materials of the Orbiter will be coated in a layer of the same burnt bone charcoal once smeared onto cave walls by our ancestors.
Andrew Norman, an ESA materials technology specialist, explained the specific needs the cave paint meets in an ESA news release.
“To go on absorbing sunlight, then convert it into infrared to radiate back out to space, its surface material needs to maintain constant ‘thermo-optical properties’—keep the same colour despite years of exposure to extreme ultraviolet radiation.
“At the same time, the shield cannot shed material or outgas vapor, because of the risk of contaminating Solar Orbiter’s highly sensitive instruments.
“And it has to avoid any build-up of static charge in the solar wind because that might threaten a disruptive or even destructive discharge.”
The black calcium phosphate coating processed from burnt bone charcoal is called “Solar Black.”
Solar Black will be applied with the “CoBlast” technique developed by Irish company Enbio. The metal surface of the Orbiter is blasted with an abrasive substance at the same time the Solar Black is applied.
John O’Donoghue, Managing Director of Enbio, explained in the release: “The new layer ends up bonded, rather than only painted or stuck on. It effectively becomes part of the metal—when you handle metal you never worry about its surface coming off in your hands.”