A NASA Spacecraft Is About to Fly Through the Sun

Godspeed.

Time for a Tan

Forget the cautionary tale of Icarus. NASA's Parker Solar Probe is just days away from flying into the Sun — or through its outer layers, depending on how you look at the maneuver — in a daring bid to glean the secrets of our star's megahot winds, Ars Technica reports.

Ever since it launched in 2018, the diminutive spacecraft, which weighs less than a ton, has been performing flybys of our star at record-breaking speeds.

But on Christmas eve, the orbiter will make its closest approach yet, coming within 3.8 million miles of the solar surface. At that toasty proximity, the Parker will be plunging straight into the Sun's upper atmosphere — and with any luck, it'll make it out in one piece to send back valuable data about what's going on down there.

"Quite simply, we want to find the birthplace of the solar wind," NASA chief of Science Nicky Fox told Ars.

Crowning Achievement

This outermost region that the Parker will be entering is known as the corona, which swirls with charged particles of plasma amidst the Sun's powerful magnetic fields. During solar eclipses, the corona is visible as an aureole of light emanating around the blacked-out star.

Despite its huge size and quite literally being the center of our existence, many facets of the Sun remain shrouded in mystery — that shroud, in this metaphor, being the corona.

Paradoxically, the corona is hundreds of times hotter than the surface of the Sun, reaching temperatures up to 3.6 million degrees Fahrenheit, compared to a comparatively mild 10,000 degrees down below. Scientists still don't agree on why this is the case; shouldn't the region closer to the core be hotter?

The corona is also thought to be the originator of solar wind, a constant flow of charged particles that suffuse the solar system, protecting it against more powerful emissions from deep space. (Its existence was predicted nearly 70 years by the NASA probe's namesake, American astrophysicist Eugune Parker.)

Close observations of the Sun have long vindicated Parker's theory, but the mechanisms behind solar winds remain unclear. Along with their extreme temperatures, the winds also travel at ludicrous speeds of around one million miles per hour, giving it its immense reach.

Feeling the Heat

So, to shine a light on all this, the Parker Solar Probe will have to get up close and personal. It's actually "touched" the Sun before, in a milestone setting flyby within the corona in 2021 — but never penetrated this deeply.

Repeating the feat will take a deft touch. As Ars explains, a solar probe must orbit at exactly the right distance where it can travel slowly enough to gather data, but also be able to dip out quickly enough so that it doesn't melt.

And of course, there's the formidable engineering challenge of designing a probe that's nimble but robust enough to survive the extreme temperatures — and temperature changes — it will be facing.

"If you think about just heating and cooling any kind of material, they either go brittle and crumble, or they may go like elastic with a continual change of property," Fox told Ars. "Obviously, with a spacecraft like this, you can't have it making a major property change. You also need something that's lightweight, and you need something that's durable."

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