Almost no one writes about Parker Solar Probe still there.

Of course, the spacecraft got attention when it was launched. It is, after all, the fastest moving thing humans have ever produced. At its top speed, pulled by the sun’s gravitational pull, the probe reaches a speed of 430,000 miles per hour, or more than one-sixth of 1 percent of the speed of light. That kind of speed will get you from New York City to Tokyo in less than a minute.

And the Parker Solar Probe also has the distinction of being the first NASA spacecraft to be named after a living person. At the time of its launch, in August 2018, physicist Eugene Parker was 91 years old.

But in the six years since the probe zipped through space and flew into the sun? Not much. Let’s face it, the astrophysical properties of the sun and its complex structure are not something most people think about on a daily basis.

However, the tiny probe—it weighs less than a metric ton, and its scientific payload is only about 110 pounds (50 kilograms)—is about to circle the star. Very literally. On Christmas Eve, the Parker Solar Probe will make its closest approach to the sun. It will come within just 3.8 million miles (6.1 million km) of the solar surface, flying into the solar atmosphere for the first time.

Yes, it can be very hot. Scientists estimate that the probe’s heat shield will withstand temperatures in excess of 2,500 degrees Fahrenheit (1,371 C) on Christmas Eve, which is the polar opposite of the North Pole.

Go Straight to the Source

I spoke to NASA’s science chief, Nicky Fox, to understand why the probe was tortured. Before moving to NASA headquarters, Fox was the project scientist for the Parker Solar Probe, and he explained that scientists really wanted to understand the origin of the solar wind.

This is the stream of charged particles that comes from the sun’s outermost layer, the corona. Scientists have wondered about this particular mystery for more than half a century, Fox explained.

“Simply, we want to find the birthplace of the solar wind,” he said.

Back in the 1950s, before we had satellites or spacecraft to measure the properties of the sun, Parker predicted the existence of this solar wind. The scientific community was somewhat skeptical about this idea—many scoffed at Parker, in fact—until the Mariner 2 mission began measuring the solar wind in 1962.

As the scientific community began to accept Parker’s theory, they wanted to know more about the solar wind, which is a fundamental component of the entire solar system. Although the solar wind is invisible to the naked eye, when you see an aurora on Earth, that’s the solar wind interacting with Earth’s magnetosphere in a very violent way.