The Parker Solar Probe, the fastest man-made object to date, will enter the Sun’s atmosphere on Christmas Eve (December 24), just 6.1 million kilometers from the surface. This is the first time a spacecraft has come this close to the Sun.
The Parker Solar Probe launched in August 2018 and is the first NASA spacecraft to be named after a living person, physicist Eugene Parker. However, it has received little attention over the past six years. The astrophysical properties of the Sun and its complex structure are not of much interest to many everyday people.
But the tiny probe is about to take a big turn. On the night of December 24, it will make its closest flyby yet to the Sun, entering the Sun’s atmosphere for the first time. Its heat shield will have to endure temperatures in excess of 1,371°C.
The mission’s main goal is to understand the origin of the solar wind, a stream of charged particles that emanates from the Sun’s outer layers, a mystery that scientists have puzzled over for more than half a century, said Nicky Fox, NASA’s chief scientist.
In the 1950s, Eugene Parker predicted the existence of the solar wind, an idea that was skeptical of the scientific community until the Mariner 2 mission measured the solar wind in 1962. The solar wind is a fundamental component of the Solar System, and when it interacts with Earth's magnetosphere, it creates auroras.
Building a spacecraft that can reach the Sun is expensive and difficult. To get it into orbit, it needs a powerful rocket. It also has to be able to withstand the extreme temperatures, radiation, and plasma in the Sun's atmosphere.
To observe the source of the solar wind, a spacecraft must travel deep into the corona. It must be powerful enough to come close to the Sun and then return to the cold of space multiple times.
The spacecraft's scientific instruments also had to be specially engineered. A solar wind measuring device, the Faraday cup, was made from Titanium-Zirconium-Molybdenum, which has a melting point of about 2,349°C. The electronic wires were also made from special materials to withstand the high temperatures.
