NASA’s Parker Solar Probe has racked up an impressive list of superlatives in its first five years of operations: It’s the closest spacecraft to the sun, the fastest human-made object and the first mission to ever “touch the sun.”
Now, Parker has one more feather to add to its sun-kissed cap: It’s the first spacecraft ever to fly through a powerful solar explosion near the sun.
As detailed in a new study published Sept. 5 in The Astrophysical Journal—exactly one year after the event occurred—Parker Solar Probe passed through a coronal mass ejection (CME).
These fierce eruptions can expel magnetic fields and sometimes billions of tons of plasma at speeds ranging from 60 to 1,900 miles (100 to 3,000 kilometers) per second. When directed toward Earth, these ejections can bend and mold our planet’s magnetic field, generating spectacular auroral shows and, if strong enough, potentially devastate satellite electronics and electrical grids on the ground.
Cruising on the far side of the sun just 5.7 million miles (9.2 million kilometers) from the solar surface—22.9 million miles (36.8 million kilometers) closer than Mercury ever gets to the sun—Parker Solar Probe first detected the CME remotely before skirting along its flank. The spacecraft later passed into the structure, crossing the wake of its leading edge (or shock wave), and then finally exited through the other side.
In all, the sun-grazing spacecraft spent nearly two days observing the CME, providing physicists an unparalleled view into these stellar events and an opportunity to study them early in their evolution.
“This is the closest to the sun we’ve ever observed a CME,” said Nour Raouafi, the Parker Solar Probe project scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, which built the spacecraft within NASA’s timeline and budget, and currently manages and operates the mission. “We’ve never seen an event of this magnitude at this distance.”
The CME on Sept. 5, 2022, was an extreme one. As Parker passed behind the shock wave, its Solar Wind Electrons, Alphas and Protons (SWEAP) instrument suite clocked particles accelerating up to 840 miles (1,350 kilometers) per second. Had it been directed toward Earth, Raouafi suspects it would have been close in magnitude to the Carrington Event—a solar storm in 1859 that is held as the most powerful on record to hit Earth.
More information: O. M. Romeo et al, Near-Sun In Situ and Remote-sensing Observations of a Coronal Mass Ejection and its Effect on the Heliospheric Current Sheet, The Astrophysical Journal (2023). DOI: 10.3847/1538-4357/ace62e
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