> Solar Orbiter’s heat shield is coated with a thin, black layer of calcium phosphate, a charcoal-like powder much like pigments used in cave paintings thousands of years ago.
“It’s funny that something as technologically advanced as this is actually very old,” Pacros said. But the coating resists degradation under the blow of intense solar ultraviolet radiation. Although the black powder does absorb some heat, it’s excellent at shedding that heat back out to space.