The space probe Parker will reach 6.1 million kilometers from the surface of the Sun and reach its outer atmosphere, the so-called solar corona. The temperature in this place reaches two million degrees Celsius. “The crown through which the Parker Solar Probe will fly is extremely hot, but very low in density,” explained engineer Susannah Darling of NASA.
“Think about the difference between putting your hand in a hot oven or in a pot of boiling water. In the oven, your hand can withstand much higher temperatures, since there is a lower density of space. Similarly, it happens on the Sun – the corona is less dense, so the spacecraft interacts with fewer particles and does not receive a huge amount of heat “
Due to this property, the heat shield, covering the Parker Solar Probe, will heat up only 1644 degrees Celsius. The screen itself is made of two carbon composite plates, connected by a core of foam plastic with a thickness of 11.5 cm. The side of the shield facing the sun is painted in white with a ceramic paint to reflect as much as possible of the sun’s rays. The length of the screen exceeds 2.4 meters, the total weight – 72 kilograms.
Source: https://hightech.fm/2018/07/20/parker P.s. I enclose the freshest photos of the probe with the heat shield already installed.