The Parker Solar Probe has made its 14th close flyby of the Sun, as part of its ongoing quest to unlock the secrets of our star.
As the morning began on Sunday, December 11, the NASA spacecraft reached its closest point to the sun’s surface, also known as the photosphere, at a distance of about 5.3 million miles (8.5 million km), braving intense radiation and intense heat to collect data related to the atmosphere. the outermost part of the star, called the “halo” or “corona”.
Scientists estimated the exact time of closest approach to the sun, or perihelion, to be around 8:16 a.m. EST (13:16 GMT), as the spacecraft is traveling at a staggering speed of about 364.639 mph (586.829 km/h). This speed is 200 times faster than a bullet fired from a gun.
Perihelion on December 11 will not be the closest of the Parker Solar Probe, which was launched aboard a Delta 4 Heavy rocket from Cape Canaveral in August 2018.
During the next flyby, the spacecraft will advance toward the sun and eventually pass near it, 3.8 million miles (6,115,500 km) from the surface. That’s seven times closer than any previous spacecraft to the sun, and about 10 times closer to the sun than the planet Mercury, and the Parker Solar Probe will experience temperatures of up to 2,500 degrees Fahrenheit (1,400 degrees Celsius).
To withstand these extreme conditions, the spacecraft is equipped with a 4.5-inch (11.43-cm) thick carbon composite shield that keeps its science payload at room temperature.
One of the primary goals of the Parker Solar Probe is to study the corona, the outermost layer of the sun’s atmosphere, and collect data that can help solve one of the sun’s most long-standing mysteries: why is the sun’s atmosphere hotter than its surface?
Theories of stellar physics indicate that pressure increases deep within the star’s plasma, and the star becomes hotter. But Halo challenges this theory. Although fragile and diffuse, the plasma in this layer is much hotter than the plasma at the surface of the Sun, the photosphere that lies beneath the corona.
Temperatures in the corona are 2 million Fahrenheit (1.1 million Celsius) and higher, and despite the fact that 1,000 miles (1,600 kilometers) below them, the photosphere is 10 million times denser and reaches temperatures of up to 10,000 Fahrenheit (5,500 degrees Celsius).
The corona is difficult to study from Earth because the light it emits dims the brighter light from the photosphere, which means the corona is only visible during a total solar eclipse, when the moon blocks light from the photosphere (scientists can also use special tools to replicate the effect).
Hence the need for the Parker Solar Probe to be “close” to our star in order to better understand the corona, which is also responsible for the release of the solar wind, a stream of charged particles that can interfere with communications and energy infrastructure here on Earth.
Since the sun is the only star close enough to be studied in this way, knowing more about it will also help scientists understand stellar objects much further afield.
The solar probe will reach its next fifteenth close to the sun on March 17, 2023, and will also reach about 5.3 million miles (8.5 million kilometers) above the sun’s surface.
Later in the year, the spacecraft will swing by Venus to adjust its trajectory near the sun as the mission draws to a close in 2025, after completing the planned 24 close passes to the sun during the mission.