A pigment used in ancient cave paintings could be put to a modern use, protecting a Solar Orbiter from the Sun's dangerous glare.
Researchers will apply burnt bone charcoal to the European Space Agency (ESA) solar orbiter's titanium heatshield in order to protect it, an ESA news release reported.
The team plans to launch the orbiter in 2017, it will look at the Sun at scorching distance of 42 million kilometers (about a quarter of the distance of Earth); at this distance the heat of the Sun will be amplified about 13 times with temperatures as high as 530 degrees Celsius (about 986 Fahrenheit ).
"The main body of the spacecraft takes cover behind a multi-layered 3.1 [meter] by 2.4 m heatshield," Pierre Olivier, Solar Orbiter's safety engineer, said in the news release.
"And Solar Orbiter's instruments will operate at the far end of 'feed-through' lines that run through the shield, some under protective covers of beryllium or glass," he said.
During the Phase-A planning stage the researchers worked to determine if the mission was possible. "We soon identified a problem with the heatshield requirements," Andrew Norman, a materials technology specialist, said in the 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 [color] despite years of exposure to extreme ultraviolet radiation," he said.
The shield cannot shed material or outgas vapor because this could damage its precious equipment.
"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," Norman said.
The researchers found they had to look for something other than carbon-fiber fabric. The researchers turned to Enbio' CoBlast technique which is used to "coat titanium medical implants," the news release reported.
"The process works for reactive metals like titanium, [aluminum] and stainless steel, which possess a surface oxide layer," commented John O'Donoghue, Managing Director of Enbio," John O'Donoghue, Managing Director of Enbio, said in the news release. We spray the metal surface with abrasive material to grit-blast this layer off, but - as the CoBlast name suggests - we also include a second 'dopant' material possessing whatever characteristics are needed. This simultaneously takes the place of the oxide layer being stripped out."
The material is called "solar black," and is made from black calcium phosphate taken from burnt bone charcoal.
"The big advantage is that 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," O'Donoghue said.
