On June 19, the Parker Solar Probe (PSP) once again approached the Sun, passing the 24th perihelion of its orbit. This event marked the completion of the mission’s basic scientific program.
The fastest and closest spacecraft to the Sun in history
PSP was launched in 2018. It is designed to study the upper, most rarefied and hottest layer of the solar atmosphere called the corona, and the processes occurring in it. The solar corona consists of plasma with a temperature of around one million degrees.
Strong solar radiation and high temperatures are not the only factors hindering the study of the corona. In order for a spacecraft to approach the Sun, its orbital velocity needs to be reduced. And this requires more fuel than it can carry. Therefore, the mission developers took advantage of gravity. They planned the PSP’s flight path so that it would periodically approach Venus. During each flyby of the planet, its gravity slowed down the probe, reducing the perihelion of its orbit.
Thanks to seven gravitational maneuvers near Venus, by the end of 2024, PSP had moved into its final orbit, with its perihelion passing just 6.2 million km from the sun’s surface. For comparison, Mercury never comes closer than 46 million km to the Sun. According to experts, at the moment of passing through perihelion, the PSP composite heat shield heats up to a temperature of 870–930 °C, which is only slightly below the melting point of silver.
Completion of the PSP basic science program
On June 19, PSP completed its 24th orbit around the Sun, once again passing at a distance of 6.2 million km from its surface and repeating its own heliocentric speed record of 687,000 km/h. Three days later, the spacecraft transmitted a signal to Earth confirming that it had survived the rendezvous and that all its systems were operating normally.
During the flight, four scientific instruments were operating on board the PSP. They have collected unique data on the corona and measured solar wind and weather in phase while the sun is in the more active stage of its 11-year cycle. This data is crucial for a better understanding of the Sun and the phenomena it causes, which pose a danger to astronauts, satellites, air travel, and even power grids on Earth.
The 24th perihelion marked the completion of the mission’s basic scientific program. The PSP will remain in its orbit and continue observations until a decision is made on its future. According to experts, the device is in excellent technical condition and will be able to study the Sun’s atmosphere during a phase when its activity will decline. However, these plans may be hindered by the planned sharp reduction in NASA’s budget, which has threatened to shut down dozens of interplanetary missions.
According to NASA
