An illustration of NASA’s Parker Solar Probe flying past the sun. The spacecraft has a carbon-carbon heat shield (carbon fibers in a carbon matrix) that can protect it from temperatures of up to 2500 F, about the melting point of steel.  (NASA’s Goddard Space Flight Center)

The Parker Solar Probe is the stuff of superlatives and marvels.

Later this week, it will pass but 5.3 million miles from the sun — much closer than Mercury or any other spacecraft  have ever come — and it will be traveling at a top speed of 101 miles per second, the fastest human-made object ever created.

It’s designed to withstand temperatures of 2,500 degrees Fahrenheit and solar radiation 475 times the intensity at Earth orbit.

And as it reaches its perihelion, or closest pass of this orbit, it will be on only its 10th of 24 planned progressively closer solar passes.  In the years ahead, it will ultimately skim into the upper corona, the atmosphere of charged and unimaginably hot plasma that surrounds the sun and other stars.  The Parker Probe will, quite literally, touch the sun.

Something rather awe-inspiring to think about this coming Sunday, when the next pass takes place.

The mission, however, surely does not have record-setting as its goal.  Rather, those records are necessary to achieve the scientific goals — to fly close enough to the sun to understand how and where the gravity-defying force of the “solar wind” originates; to determine the structure and dynamics of the magnetic fields and switchbacks that are hotly debated as a possible source of that solar wind; and to resolve the mystery of why the sun’s corona is unexpectedly hotter than the solar “surface” below it.

“Parker Solar Probe is already telling us many important things about the sun that we didn’t know,” said Nour Raouafi, Parker Solar Probe project scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland.  “We are definitely getting closer to understanding some of the big questions we had before, such as the source of the solar wind.  But we have to be mindful that in whatever we find, the Sun is always changing.”

And incidently, he said, more than 99.9 percent of all the matter in our solar system is in and around the sun.


Solar wind activity at different scales as imaged by the Parker Probe’s Wide-field Imager (WISPR) instrument earlier this year during.
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