Nicki Viall, a heliophysicist at Goddard Space Flight Center, shares her excitement over the Parker Solar Probe — the spacecraft that will allow scientists to "touch" the Sun.


The Sun is an elemental presence in our lives.  Warmth, light, cycles of day, night, and seasons are woven into our minds and bodies. Much of our ancient mythology justifiably centers around our star, including the story of Icarus, who attempted to fly to the Sun. Icarus’s wings were made of feathers and wax, which melted as he approached the Sun, sending him falling back to earth and his death. The story of Icarus was meant to illustrate the concept of hubris; that humans must humbly accept their gods-given limitations. There are places we are not meant to go; mysteries we are not meant to understand.

Luckily for us, science rejects the idea of hubris. There are always places that we do not know how to explore… yet. But they fall away one by one. Not long ago, no human had never climbed Mount Everest or sat in a submarine on the bottom of the ocean. Nor had we sent mobile laboratories to Mars or spent more than a decade slingshoting around the moons of Saturn. Sometimes there is just a need to be patient. We may not have the technology yet to send an autonomous underwater probe to explore the oceans of Jupiter’s moon Europa, but someday soon, we will.

One place that has still been off-limits, going all the way back to the myth of Icarus, is the region of our solar system very near the Sun. We have spent centuries studying the Sun from the surface of Earth or near-Earth satellites, but it is difficult to approach our home star. Radiation is intense, temperatures are high, and we just didn’t have the technology to build a spacecraft that could stand up to the conditions close to the Sun. Apparently now is the time to challenge those limitations.  Engineers and scientists are currently building and testing the Parker Solar Probe, the first mission planned to make a close approach to the Sun and directly measure the conditions in the Sun’s outer atmosphere.

The numbers are pretty impressive. The Parker Solar Probe will be sent hurtling around the Sun at over 430,000 miles per hour, fast enough to travel between Washington D.C. and Philadelphia in one second. The instruments and spacecraft will be protected by a 5-inch thick carbon-composite heat shield, built to withstand temperatures of over 2500 degrees Fahrenheit. Parker will fly as close as 3.7 million miles away from the Sun, and if that seems like a safe distance, remember that the Sun has a diameter of 860,000 miles. From that location, we will be able to taste, sniff, and take the temperature of the gases in the solar corona.

Many millions of people across the United States were recently treated to a rare view of this region of the Sun; it can be seen as glowing streamers of light that extend from the Sun when it is blocked by the moon during a total solar eclipse. For me, it is an intense emotional experience to view a total eclipse. The corona is always there, shining in the sky, but its diffuse light is normally completely overwhelmed by the bright surface of the Sun. Not only is the corona beautiful, but it is deeply mysterious. The surface of the Sun is approximately 10,000 degrees Fahrenheit, but the gases right above the surface, whipped up by magnetic storms and injected with high-energy plasma, can reach several million degrees. Yes, we have some clues about why this is so, but at a basic level, we really don’t understand yet how our own star works. Time to go out there and see for ourselves.

In this episode of Orbital Path, we talk with Nicki Viall, a heliophysicist at NASA’s Goddard Space Flight Center. Nicki has dedicated her career to studying the corona and the violent magnetic storms that shape and heat it. Nicki has been observing the Sun, like all of us, from a distance, waiting patiently for the time when it would become possible to actually go there. In buildings near her office, the Parker Solar Probe is taking shape, being put through its paces to make sure it can stand up to the demands of its mission. Icarus made his wings of feather and wax, but the Parker Solar Probe is built of sturdier stuff: spacecraft-grade aluminum and carbon composite. Nicki is well ready to put on her wings, via a robotic avatar, and to fly to the Sun.

Orbital Path is produced by PRX and supported by the Alfred P. Sloan Foundation. Don't miss PRX's other science podcasts: Transistor and Outside Magazine.


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October 8, 2017 at 4:19 pm

This comment should go straight to Michelle Thaller as I could find no other way of sending her a message.

In the documentary "The Great American Eclipse" episode 5 about 18 minutes into the episode Michelle states. “We’re one of the only planets where the moon completely covers up the Sun and there’s actually this dark shadow that’s cast." This is simply not true. I have seen the Galilean Moons cast shadows on Jupiter. Plus, simple calculations show that on Jupiter these moons have a larger angular diameter than the Sun.
This has come to be a problem when I participate in outreach events and people come up who have seen this and insist that it is true.

Her statement in this documentary is not the first place I’ve seen this. In the documentary "Secret History of the Sun" about 4 minutes into it the commentator says:
“We are very lucky. The Earth is the only place in the Solar System from where you can witness a total eclipse. Because even though the moon is 400 times smaller than the sun, it's also 400 times closer. So in a total eclipse, it appears to be exactly the same size.” While misstated here, it is clear he was trying to say "A total eclipse where the Sun and moon are the same size allowing us to see the corona during the eclipse".
Please help us nip this rumor in the bud before it becomes one of those giant super Moon or giant Mars rumors.

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October 9, 2017 at 2:29 am

Dr. Thaller,
The story of Icarus is an excellent segue into the Parker Solar Probe. However, I must mention two apparent inconsistencies in your article.
First, the claim that the moral of the Icarus story is "that humans must humbly accept their gods-given limitations." On the Cambridge site (see link), the Icarus story doesn't invest any such gods-vs-science implication in that narrative. His father merely warns Icarus to be careful of physical tolerances.

Second, the assertion "science rejects the idea of hubris" seems to contain a misnomer. Hubris is defined as "excessive pride or self-confidence.", while your point seems to be that "science rejects artificial limitations". Both statements seem arguably true: hubris is to be avoided in all walks of life, not just science; and, some ethical limitations in science must be acknowledged. Even the most progressive views of science acknowledge that it is bound by limitations of morality.

I truly hope that you take this as a positive critique, since it's only intended to clarify the reader's understanding of your progressive view of science.

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