The first results to come down from NASA's record-setting Parker Solar Probe have impressed the pioneering astrophysicist who lent the spacecraft his name.
Yesterday (Dec. 4), mission team members published four studies reporting what the PSP observed during its first two close approaches to the sun. These perihelion passages were epic and audacious, taking the probe within a mere 15 million miles (24 million kilometers) of our star at blistering speeds that topped 200,000 mph (320,000 km/h).
No spacecraft has ever gotten closer to the sun, or traveled so fast relative to it.
The PSP takes its name from 92-year-old Eugene Parker, who in the 1950s controversially proposed that a stream of charged particles flows constantly from the sun. The existence of this stream, known as the solar wind, was confirmed shortly thereafter by spacecraft observations.
Parker, who's now an emeritus professor at the University of Chicago, made a number of other important contributions to our understanding of the sun during his long career — so many, in fact, that he's regarded as the father of modern heliophysics, said Nicky Fox, director of the Heliophysics Division at NASA headquarters in Washington, D.C.
"He basically gave birth to an entire physics discipline," Fox said yesterday during a "NASA Live" event devoted to discussing the new PSP results. While humanity has sought to figure out the sun since time immemorial, she added, "really understanding that the sun had such a profound effect on Earth is really due to Gene Parker."
This outsize influence explains why NASA broke the mold with its naming of the PSP. It's the only agency spacecraft ever named after a living person.
Fox explained during yesterday's event that she paid Parker a visit a few months ago to celebrate the one-year anniversary of the spacecraft's arrival in orbit around the sun.
The PSP launched on Aug. 12, 2018, with two big mission goals in mind: to determine how the solar wind gets accelerated to such high speeds (more than 1 million mph, or 1.6 million km/h), and to understand why the sun's outer atmosphere, or corona, is so much hotter than the solar surface. (Temperatures in the corona can exceed 2 million degrees Fahrenheit, or 1.1 million degrees Celsius. The surface is just 11,000 F, or 6,000 C.)
During their meeting, which was captured on video and shared during the NASA Live event, Fox gave Parker a sneak peek at the results that were published yesterday. These data show, among other things, that one component of the solar wind appears to originate near the star's equator, in coronal "holes" that are cooler and less dense than the rest of the outer atmosphere.
PSP also found surprising "switchbacks" in the solar magnetic field flowing close to the sun: The field's orientation, as measured by the probe, sometimes flipped 180 degrees, then reversed itself again within just seconds or minutes.
"Well, all I can say is, 'Wow,'" Parker said in the video. "When you go on a space mission, you always run into mysterious things, eventually figuring them out. But I wouldn't have expected anything like that."
Parker also reflected on the PSP's launch from Cape Canaveral Air Force Station in Florida, which he attended.
"I was very moved by the fact that that spacecraft was going off into the night sky, and he'll never come back," Parker said. His next words came more slowly, as the physicist appeared to get choked up: "Sort of sad, you know — your old friend."
Fox commiserated, replying that she experienced some separation anxiety as the spacecraft sped away from Earth.
"It was like watching a member of the team, because after working with that spacecraft for so long, she became a person, and she became part of the team," Fox told Parker. "And to say goodbye to her was really, really tough."
We'll be hearing lots more from the PSP in the years to come. The spacecraft has completed just three of the 24 planned perihelion passes that will take place through the mission's end in 2025. And the last few close approaches will be the most exciting, and possibly the most fruitful.
The PSP will pare down its perihelion distance repeatedly via trajectory-altering flybys of Venus, the next of which will occur next month. By 2025, if all goes according to plan, the spacecraft will get within a mere 3.83 million miles (6.16 million km) of the sun's surface at closest approach. And those encounters will feature top speeds of 430,000 mph (690,000 km/h), mission team members have said.
- Here's What Earth Looks Like When You're Heading to the Sun
- Solar Quiz: How Well Do You Know Our Sun?
- Launch Photos! NASA's Parker Solar Probe Blasts Off to Touch the Sun
Mike Wall's book about the search for alien life, "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), is out now. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.