Space probe grazes the sun

A NASA spacecraft has breached the sun’s outer atmosphere for the first time, scientists announced on Tuesday. The Parker Solar Probe first crossed into the unexplored region, known as the corona, back in April, but it took time for researchers to confirm the data. The breakthrough gives scientists a closer look than ever at the star that fuels our planet.

The Parker Solar Probe launched aboard a Delta IV Heavy rocket back in 2018 and flew toward the sun’s outer edge carrying cutting-edge data-collection technology. A shield protects it from the extreme heat: The corona is hundreds of times hotter than the sun’s surface, reaching millions of degrees. The mission has already made discoveries, including the existence of back-and-forth formations in the solar wind, according to NASA.

Scientists have wanted to send a mission to “touch” the sun for decades. The spacecraft is named after Eugene Parker, now 91, who accurately predicted the existence of solar wind, the stream of ionized particles emitted by the sun.

“Flying so close to the Sun, Parker Solar Probe now senses conditions in the magnetically dominated layer of the solar atmosphere—the corona—that we never could before,” said Nour Raouafi, the probe’s project scientist. “We see evidence of being in the corona in magnetic field data, solar wind data, and visually in images. We can actually see the spacecraft flying through coronal structures that can be observed during a total solar eclipse.”

As of April, Parker had moved to within 8 million miles of the sun’s surface and crossed into the corona at least three times. Its first visit lasted five hours, and it zipped through the corona at 62 miles per second. During the flybys, it gathered data on a region known as the Alfvén surface—above it, the solar wind heads off into space, while below it, gravity keeps it bound to the sun. During its trip, Parker revealed that the Alfvén surface was not smooth and round, but full of spikes due to solar activity.

The irradiance at this region of the sun is more than 450 times greater than that at the surface of Earth, wrote CalTech researcher Christina Cohen, who wrote about the Parker data in Physics. In order to get Parker so close to the sun, the spacecraft employed a heat-resistant shield and made automatic adjustments to keep important instruments under the shade at all times.

Data on later flybys continue to roll in from Parker. It approached for the 10th time last month, and it will continue to speed up and move deeper into the corona as it orbits the sun. By 2024, it should be traveling faster than any other object from Earth has ever gone. Its final orbit is scheduled for 2025.

The researchers hope that better understanding the sun, particularly the active corona region, will allow them to protect satellites, astronauts, and power grids from solar activity, said Thomas Zurbuchen, NASA’s science mission chief.