Parker must always keep his heat shield pointed at the Sun. (NASA-JHU-APL)
The feat was accomplished by the ship Parker Solar Probe, which plunged, for a moment, into a region around our star that scientists call the corona.
It happened in April, but data analysis has now confirmed it.
The Parker ship had to withstand the heat and intense radiation, but gathered new insights into how the Sun works.
“Just as the landing on the Moon allowed scientists to understand how it formed, touching the Sun is a giant step for humanity that helps us discover critical information about our closest star and its influence on the Solar System,” said Nicola Fox, director of NASA’s heliophysical science division.
Parker Solar Probe is one of the agency’s boldest missions.
Launched three years ago, its objective is to make repeated passes and increasingly closer to the Sun.
The spacecraft is moving at a colossal speed, over 500,000 km / h. The strategy is to get in and out fast, making measurements of the solar environment with an array of instruments deployed behind a thick heat shield.
On April 28 of this year, Parker crossed what is called Alfvén’s critical limit.
This is the outer edge of the crown. It is the point where the solar material that is normally attached to the Sun by gravity and magnetic forces is released to flow through space.
Parker found the limit at about 13 million kilometers above the visible surface, or photosphere, of the Sun.
The probe data suggests that it actually went over and under the limit three different times over the course of five hours, according to Stuart Bale of the University of California at Berkeley.
“We saw that the conditions changed completely,” he told reporters.
“Inside the corona, the Sun’s magnetic field became much stronger and dominated the motion of the particles there. So the spacecraft was surrounded by material that was actually in contact with the Sun ”.
Researchers are fascinated with the crown because it is where they take place some key processes that currently defy explanation.
One is what appears to be counterintuitive overheating. The temperature of the Sun in its photosphere is approximately 6,000 ° C, but within the corona it can reach a astonishing million degrees or more.
It is also within this region that the outward flow of charged particles (electrons, protons, and heavy ions) suddenly accelerates into a supersonic wind. Once again, the mechanism is a puzzle.
“The problem is that the traces of the physical processes that give rise to the solar wind are erased by the journey that the solar wind makes from the solar corona to Earth and beyond,” explains Nour Raouafi, from the John Hopkins Laboratory of Applied Physics. .
“It’s the reason Parker flies through this mysterious region to tell us what’s going on there.”
Parker’s science team will collect much more data as the probe moves deeper and deeper into the crown in future flybys of the Sun. It should reach 7 million kilometers of the photosphere by 2025.
Parker’s data, and those from other solar observatories, have direct relevance to everyone living on Earth.
The biggest bursts from the Sun can shake up our planet’s magnetic field. In the process, communications can be disrupted, satellites can be disconnected, and power grids will be vulnerable to electrical surges.
Scientists are trying to forecast these “storms” and Parker promises new and valuable information to help them do so.
The latest mission results are presented at the Fall Meeting of the American Geophysical Union in New Orleans.