NASA: The Parker Solar Probe will flirt with the sun for Christmas

This Christmas, NASA's Parker Solar Probe will pass through the sun's atmosphere. She will approach it as no human-made object has before.

According to NASA calculations, the probe will approach approximately six million kilometers from the surface of the sun. The meeting is scheduled for December 24 around 1:00 p.m. (Swiss time). It will take place without witnesses, “because we will not have radio contact with the probe at that time,” explains astrophysicist Volker Bothmer of the University of Göttingen (D).

Only on the night of December 27 will the team of scientists expect a signal – if all goes well. The probe will then send a “sign of life” to Earth, through a brief autonomous radio signal – comparable to the flashing of a lighthouse.

The first data will not be available until the end of January, when the probe's main antenna points towards Earth. However, it will take “several years to evaluate and understand all the data,” says Mr. Bothmer, who heads German participation in the mission.

And 690,000 km/h

The probe, the size of a small car, has a speed of around 690,000 km/h at the planned point closest to the sun and withstands temperatures of around 1000 degrees Celsius, NASA writes. It therefore flies faster than any other object built by humans until now.

If, however, its 11.4-centimeter-thick carbon heat shield were moved only slightly, much of the instrumentation, including the camera, would burn up.

In particular, scientists hope to learn why the sun's outer atmosphere is much hotter than its surface and, therefore, how the atmospheres of other stars work. The outermost part of the sun's atmosphere is in fact 200 times hotter than its surface.

Solar winds and storms

Parker Solar Probe, launched in August 2018 and weighing around 700 kilograms, orbits the sun in highly elliptical orbits. During its first flyby in October 2018, it had already come as close as no other spacecraft had before, with a distance of 42.7 million kilometers.

In 2021, it was the first probe to pass through the sun's outermost atmospheric layer, the corona. “For the first time in history, a space probe has touched the sun,” NASA wrote at the time. In 2023, it even came a little more than 7 million kilometers from the surface of the sun.

According to Mr. Bothmer, getting within six million kilometers means diving even deeper into the solar corona: “This will allow us to obtain data on areas of the solar atmosphere that have never existed before. At this proximity, we will then find ourselves in the regions of birth of the solar wind and solar storms.

For comparison, the Earth is on average about 150 million kilometers from the sun and the closest planet to the sun, Mercury, is about 58 million kilometers.