Solar Orbiter

The Solar Orbiter is a NASA-ESA mission to look at the Suns poles. In the dark of space, Solar Orbiter faces temperatures of minus 300 degrees Fahrenheit. At closest approach, 26 million miles from the Sun, it will encounter intense heat and radiation. The Solar Orbiter’s 324-pound heat shield reflects and guides heat away from the spacecraft and can withstand up to 970 F

Animation of a portion of Solar Orbiter’s highly inclined orbit.
Credits: ESA/ATG medialab

The heat shield is built like a 10-foot-by-8-foot sandwich. The front layer — wafer-thin sheets of titanium foil — strongly reflects heat. A honeycomb-patterned aluminum base, covered in more foil insulation, forms the inner slice closest to the spacecraft and provides support.

Star-shaped titanium brackets keep the layers in place, like a toothpick tasked to hold bread together, but notably, this sandwich is missing its filling. The nearly 10-inch gap in the shield funnels heat out to space. A smaller, second gap lies between the inner slice and the spacecraft. Overall, the shield is 15 inches thick. It also has several eyes: peepholes for five of the spacecraft’s remote-sensing instruments to peer through.

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.


Solar Orbiter was built by Airbus Defence and Space, and contains 10 instruments: nine provided by ESA member states and ESA. NASA provided one instrument (SoloHI) and an additional sensor, the Heavy Ion Sensor, which is part of the Solar Wind Analyzer (SWA) instrument suite.